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Identification of novel sequences and codon usage in Strongyloides stercoralis
... These larvae are developmentally arrested, non-feeding, stress resistant, and long lived345. A high degree of specificity between these stages has been suggested by expressed sequence tag (EST) based analysis of free living L1 and L3i larvae for S. stercoralis678. These comparisons, however, are based on short reads of cDNA libraries and assumptions about abundance. ...
... ESTs (11,335) were identified from L1 and L3i cDNA libraries created as part of the nematode EST project [6,7]. ESTs were organized into 3,571 contigs by bioinformatics analysis [14]. ...
Background
Differences between noninfective first-stage (L1) and infective third-stage (L3i) larvae of parasitic nematode Strongyloides stercoralis at the molecular level are relatively uncharacterized. DNA microarrays were developed and utilized for this purpose.Methods and findingsOligonucleotide hybridization probes for the array were designed to bind 3,571 putative mRNA transcripts predicted by analysis of 11,335 expressed sequence tags (ESTs) obtained as part of the Nematode EST project. RNA obtained from S. stercoralis L3i and L1 was co-hybridized to each array after labeling the individual samples with different fluorescent tags. Bioinformatic predictions of gene function were developed using a novel cDNA Annotation System software. We identified 935 differentially expressed genes (469 L3i-biased; 466 L1-biased) having two-fold expression differences or greater and microarray signals with a p value
... Understanding the codon usage pattern of M. incognita is crucial for developing effective control strategies against this devastating plant parasite, and Table 4 Correlation analysis between ENC and several other CUB indices of Meloidogyne incognita. Previous studies have examined the role of codon usage bias and evolutionary forces in shaping the genomes of animal parasitic nematodes, such as Ancylostoma ceylanicum (Singh, 2021), Brugia malayi (Hammond, 1994), Ancylostoma caninum (Fadiel et al., 2002), Strongyloides stercoralis (Moore et al., 1996), the free-living nematode Caenorhabditis elegans (Stenico et al., 1994) as well as in selected expressed sequence tags of non-Caenorhabditis nematode species, including Globodera, Meloidogyne, Pristionchus, and Strongyloides (Mitreva et al., 2006). However, despite their significant economic importance, no such analysis has been conducted for individual plant parasitic nematodes. ...
... Expression of transgenes requires the use of endogenous regulatory regions; C. elegans regulatory regions generally do not function in Strongyloides (Junio et al., 2008;Li et al., 2006). Codon usage also differs widely across nematode species, and expression of genes from other species in Strongyloides often requires codon optimization of the genes for Strongyloides (Hunt et al., 2016;Lok et al., 2017;Massey et al., 2001;Mitreva et al., 2006;Moore et al., 1996). Intragonadal microinjection has also been used to generate transgenics in the closely related nematode Parastrongyloides trichosuri, a parasite of Australian brushtail possums that can cycle through multiple free-living generations (Grant et al., 2006). ...
Human-parasitic nematodes infect over a quarter of the world's population and are a major cause of morbidity in low-resource settings. Currently available treatments have not been sufficient to eliminate infections in endemic areas, and drug resistance is an increasing concern, making new treatment options a priority. The development of new treatments requires an improved understanding of the basic biology of these nematodes. Specifically, a better understanding of parasitic nematode development, reproduction and behavior may yield novel drug targets or new opportunities for intervention such as repellents or traps. Until recently, our ability to study parasitic nematode biology was limited because few tools were available for their genetic manipulation. This is now changing as a result of recent advances in the large-scale sequencing of nematode genomes and the development of new techniques for their genetic manipulation. Notably, skin-penetrating gastrointestinal nematodes in the genus Strongyloides are now amenable to transgenesis, RNAi and CRISPR/Cas9-mediated targeted mutagenesis, positioning the Strongyloides species as model parasitic nematode systems. A number of other mammalian-parasitic nematodes, including the giant roundworm Ascaris suum and the tissue-dwelling filarial nematode Brugia malayi, are also now amenable to transgenesis and/or RNAi in some contexts. Using these tools, recent studies of Strongyloides species have already provided insight into the molecular pathways that control the developmental decision to form infective larvae and that drive the host-seeking behaviors of infective larvae. Ultimately, a mechanistic understanding of these processes could lead to the development of new avenues for nematode control.
... Molecular diagnosis-Molecular diagnostics -using standard (and/or nested-) PCR, qPCR or loop-mediated isothermal amplification assays -have been increasingly gaining traction for use stool-based assays given their high degree of specificity and sensitivity (ten Hove et al. 2009;Verweij et al. 2009;Taniuchi et al. 2011;Mejia et al. 2013;Sultana et al. 2013;Watts et al. 2014;Easton et al. 2016;Llewellyn et al. 2016). Indeed, the improved specificity relies on the specific DNA targets used [18S rRNA, IST1, cytochrome c oxidase subunit 1 or the highly repetitive interspersed repeat sequence (Moore et al. 1996)] and the improved sensitivity has resulted from better methods for DNA extraction in stool (ten Hove et al. 2009;Taniuchi et al. 2011;Liu et al. 2013;Mejia et al. 2013;Sultana et al. 2013;Easton et al. 2016). These molecular diagnostic techniques likely identify active S. stercoralis infection as positivity has been shown to be lost following definitive treatment. ...
The majority of the 30–100 million people infected with
Strongyloides stercoralis
, a soil transmitted intestinal nematode, have subclinical (or asymptomatic) infections. These infections are commonly chronic and longstanding because of the autoinfective process associated with its unique life cycle. A change in immune status can increase parasite numbers, leading to hyperinfection syndrome, dissemination, and death if unrecognized. Corticosteroid use and HTLV-1 infection are most commonly associated with the hyperinfection syndrome.
Strongyloides
adult parasites reside in the small intestine and induce immune responses both local and systemic that remain poorly characterized. Definitive diagnosis of
S. stercoralis
infection is based on stool examinations for larvae, but newer diagnostics – including new immunoassays and molecular tests – will assume primacy in the next few years. Although good treatment options exist for infection and control of this infection might be possible,
S. stercoralis
remains largely neglected.
... There are few genomic studies on S. stercoralis and related species. Initially, the molecular studies on Strongyloides were focused on phylogenetic studies using different approaches (Moore et al., 1996;Ramachandran et al., 1997;Dorris and Blaxter, 2000;Dorris et al., 2002;Hu et al., 2003). The results of these studies suggest that Strongyloides is a particular group from a phylogenetic point of view. ...
Strongyloidiasis (caused by Strongyloides stercoralis, and to a lesser extent by Strongyloides fuelleborni) is one of the most neglected tropical diseases with endemic areas and affecting more than 100 million people worldwide. Chronic infections in endemic areas can be maintained for decades through the autoinfective cycle with the L3 filariform larvae. In these endemic areas, misdiagnosis, inadequate treatment and the facilitation of the hyperinfection syndrome by immunosuppression are frequent and contribute to a high mortality rate. Despite the serious health impact of strongyloidiasis, it is a neglected disease and very little is known about this parasite and the disease when compared to other helminth infections. Control of the disease is difficult because of the many gaps in our knowledge of strongyloidiasis. We examine the recent literature on different aspects of strongyloidiasis with emphasis in those aspects that need further research.
Copyright © 2015 Elsevier Ltd. All rights reserved.
... Atualmente, pesquisas têm buscado diferenças na expressão gênica entre estágios larvares, o que permitiria um melhor entendimento da biologia do Strongyloides (Viney, 2006). Diversos trabalhos estão sendo realizados para se determinar seqüências de genes desse parasito, até mesmo com o objetivo de que sejam utilizadas no diagnóstico clínico por meio de variantes de métodos da reação em cadeia da polimerase (PCR) (Putland et al., 1993; Moore et al., 1996; Dorris & Blaxter, 2000; Massey Jr. et al., 2001, Gallego et al., 2005 Viney, 2006). Entretanto, nenhuma seqüência alvo do parasito que pudesse ser empregada como diagnóstico pela PCR foi descrita até o momento. ...
Strongyloidiasis is caused by the intestinal nematode Strongyloides stercoralis and
it typically occurs in the asymptomatic form. However, it can cause hyperinfection
and dissemination in immunosuppressed patients, especially if they are under
corticoid therapy. Definitive diagnosis is made by the detection of larvae in fecal
samples. However, as the number of parasites in the host is very low in most cases
and the elimination of larvae in the feces is not frequent, the diagnosis of this disease
by parasitological methods becomes extremely difficult. The development of
reliable immunological assays is an important alternative approach for the diagnosis
of strongyloidiasis. One of the major limitations in developing more sensitive and
specific immunological tests is the difficulty in obtaining sufficient amounts of
parasites to have well-defined fractions or molecules. Thus, the development of
reliable serological assays for the strongyloidiasis diagnosis that does not need
larvae as antigenic component is imperative.
... In addition, Ss-eat-6 induced a significant reduction in larval survival after DNA immunization [23]. Two antigens, Ss-NIE-1 and Ss-IR, were selected based on their high degree of immunogenicity in humans infected with S. stercoralis [27,293031. Results from the current study demonstrate that immunization with the single antigen Ss-IR induced high and consistent levels of protective immunity. ...
Human intestinal infections with the nematode Strongyloides stercoralis remain a significant problem worldwide and a vaccine would be a useful addition to the tools available to prevent and control this infection. The goal of this study was to test single antigens for their efficacy in a vaccine against S. stercoralis larvae in mice. Alum was used as the adjuvant in these studies and antigens selected for analysis were either recognized by protective human IgG (Ss-TMY-1, Ss-EAT-6, and Ss-LEC-5) or were known to be highly immunogenic in humans (Ss-NIE-1 and Ss-IR). Only mice immunized with the Ss-IR antigen demonstrated a significant decrease of approximately 80% in the survival of larval parasites in the challenge infection. Antibodies, recovered from mice with protective immunity to S. stercoralis after immunization with Ss-IR, were used to locate the antigen in the larvae. Confocal microscopy revealed that IgG from mice immunized with Ss-IR bound to the surface of the parasites and observations by electron microscopy indicated that IgG bound to granules in the glandular esophagus. Serum collected from mice immunized with Ss-IR passively transferred immunity to naïve mice. These studies demonstrate that Ss-IR, in combination with alum, induces high levels of protective immunity through an antibody dependent mechanism and may therefore be suitable for further development as a vaccine against human strongyloidiasis.
... The size and sequence properties suggest the presence of distinct shsp-17 Phylogenetic comparisons with sHSPs originating from other nematodes showed low overall sequence identities (21-35%), especially among species at the evolutionary extremes of phylum Nematoda [33]. However, higher homologies of 59% and 61% between Sra-HSP-17.1, Sra-HSP-17.2 and the deduced S. stercoralis sHSP (Sst-HSP-17) partial sequence were observed [34]. S. ratti and S. stercoralis are from the suggested that Strongyloides belongs to the order Rhabditida, which also contains C. elegans [35], and C. elegans and Strongyloides might be slightly more closely related to each other than either of them is to filaria or Trichinella [36]. ...
In a search for molecules involved in the interaction between intestinal nematodes and mammalian mucosal host cells, we performed MS to identify excretory–secretory proteins from Strongyloides ratti . In the excretory–secretory proteins of the parasitic female stage, we detected, in addition to other peptides, peptides homologous with the Caenorhabditis elegans heat shock protein (HSP)‐17, named Sra‐ HSP‐17.1 (∼ 19 kDa) and Sra‐ HSP‐17.2 (∼ 18 kDa), with 49% amino acid identity. The full‐length cDNAs (483 bp and 474 bp, respectively) were identified, and the genomic organization was analyzed. To allow further characterization, the proteins were recombinantly expressed and purified. Profiling of transcription by quantitative real‐time‐PCR and of protein by ELISA in various developmental stages revealed parasitic female‐specific expression. Sequence analyses of both the DNA and amino acid sequences showed that the two proteins share a conserved α‐crystallin domain and variable N‐terminals. The Sra‐ HSP‐17s showed the highest homology with the deduced small HSP sequence of the human pathogen Strongyloides stercoralis. We observed strong immunogenicity of both proteins, leading to strong IgG responses following infection of rats. Flow cytometric analysis indicated the binding of Sra‐ HSP‐17s to the monocyte–macrophage lineage but not to peripheral lymphocytes or neutrophils. A rat intestinal epithelial cell line showed dose‐dependent binding to Sra‐ HSP‐17.1, but not to Sra‐ HSP‐17.2. Exposed monocytes released interleukin‐10 but not tumor necrosis factor‐α in response to Sra‐ HSP‐17s, suggesting the possible involvement of secreted female proteins in host immune responses.
Database
Nucleotide sequences for Strongyloides ratti heat shock proteins 17.1 and 17.2 have been submitted to the GenBank database under the accession numbers HQ848950 and HQ848951
... Cloning, expression and purification of strongylastacin A S. stercoralis cDNA library constructed in lambda Zap XR phage has been described previously (24). The phage encoding strongylastacin was in vivo excised into pBluescript. ...
The infective, microscopic Strongyloides stercoralis larvae in contaminated soil can penetrate human skin with the help of excretory/secretory proteases. These proteases play a critical role in infection and transmigration of the parasite to the intestines. Strongylastacin is similar to astacin (from the digestive gland of the crayfish Astacus astacus), a multi-domain protein with a signal peptide, a pro-enzyme, a catalytic domain containing the zinc binding consensus astacin family signature sequence HEXXHXXGFXHEXXRXDR, and a second conserved zinc binding motif SIMHY at N- terminal region. An EGF-1 like domain and a CUB domain are located at the COOH- terminal. In this study, the excretory/secretory Strongylastacin gene from S. stercoralis infective larval stage was cloned and expressed as a 45 kDa in Escherichia coli. Immunoblot analysis showed the presence of natural IgG antibodies against strongylastacin in six infected and six non-endemic normal sera. These findings were confirmed in an ELISA of 32 S. stercoralis infected and 32 presumed normal human sera; all contained natural anti-strongylastacin IgG antibodies. By contrast, IgE antibodies specific to strongylastacin were present in sera from individuals infected with S. stercoralis but not in uninfected control sera. Moreover, recombinant strongylastacin did not cross-react with IgE antibodies either from patients infected with filaria or patients with tropical pulmonary eosinophilic (TPE) who had increased IgE antibodies. The present authors conclude that strongylastacin, an excretory/secretory antigen, elicits specific IgE antibodies in S. stercoralis infected humans. Non-specific IgG antibodies to strongylastacin are present in both infected and normal humans. Further investigation is needed to understand the role of the host protective response against strongylastacin.
... The preparation of the overnight at room temperature in a volumetric flask, which had five times the capacity of the volume of the protein solution. All library from the infective filariform (L3) stage of S. stercoralis has been described [17]. For immunoscreening, we used a previously steps of purification and dialysis were done at room temperature. ...
Because diagnosis of strongyloidiasis by stool examination is unreliable and because of the potential for serious disease
in Strongyloides infections, there is need for improved diagnostic aids to facilitate recognition and treatment of this parasitic infection.
Serologic testing, when available, requires antigen preparation from infected primates or dogs that can be difficult to maintain.
Several recombinant clones from a cDNA library prepared from the infective stage of Strongyloides stercoralis were characterized. Serologic results indicate that the recombinant proteins were equally or more reactive than the larval
somatic antigen. No cross-reactivity with recombinant antigen 5a was found with sera from patients with filarial or intestinal
nematode infections. Recombinant antigens 5a and 12a detected parasite-specific IgE and IgG4 antibodies in Strongyloides-infected patients. Sequence analysis showed these antigens to be rich in proline and charged amino acids. Lack of homology
from database searches suggests that the antigens are unique. These recombinant antigens should be useful in diagnostic and
epidemiologic studies of strongyloidiasis.
... Preparation of the library from infective-stage (L3) larvae obtained from an infected human has been described [9] , as has the protocol used for immunoscre- ening [8]. After inducing the phage by adding 10 mM isopropyl-1-b-D-thio-1-galactopyranoside (Gold Biotechnology , St. Louis, MO) for 3.5 h at 37 8C, about 200 000 plaques were screened. ...
Due to the process of internal autoinfection, even chronic asymptomatic infections with Strongyloides stercoralis have the potential to become severe disseminated disease with fatal outcome. Intermittent and scanty larval excretion makes parasitologic diagnosis difficult. Serodiagnosis is helpful, but antigen preparation from infective larvae requires access to patients or immunosuppressed experimental animals. For these reasons, attention has turned to recombinant antigens for immunodiagnosis. A 31-kDa candidate antigen (NIE) derived from an L3 cDNA library is described in this report. Multiple alignment of the deduced amino acid sequence of NIE showed approximately 12-18% identity with various other organisms, including 17.9% of Asp1 of Ancylostoma caninum, 12.6% of Hemonchus contortus, and 17.6% of insect venom allergen 5 of yellow jacket. By ELISA, antibodies to the purified recombinant NIE antigen were demonstrated in 87.5% of 48 sera from strongyloides-infected patients and in only 6.5% of sera from presumed normal controls. Immunoreactivity of purified NIE antigen with parasite-specific IgE from sera of strongyloides-infected patients indicated its potential use as an immediate sensitivity skin test antigen. This application of the NIE antigen was supported by its capacity to trigger release of histamine upon in vitro exposure to blood from strongyloides-infected patients and its failure to produce histamine release from blood of normal controls.
Most of the 30 to 100 million people infected with Strongyloides stercoralis have subclinical (or asymptomatic) infections. These infections are commonly chronic and longstanding. A change in immune status can increase parasite numbers, leading to hyperinfection syndrome, dissemination, and death if unrecognized. The use of corticosteroids and HTLV-1 infection are most commonly associated with the hyperinfection syndrome. Strongyloides adult parasites reside in the small intestine and induce immune responses that are like other nematodes. Definitive diagnosis of S stercoralis infection is based on stool examinations for larvae. S stercoralis remains largely neglected.
Individuals with idiopathic Parkinson's disease (IPD) have long been treated with dopamine-based medications such as levodopa. While dopaminergic medication is considered to be quite successful in treating the limb motor deficits of IPD, its effect on speech is unclear. Fifteen participants with IPD provided speech samples of a monologue and reading passage while optimally medicated and while off dopaminergic medications for 15 hours. Ten experienced speech-language pathologists (SLPs) perceptually rated speech samples using a visual analog scale for the dimensions of intelligibility, naturalness, and voice quality. Speech rate, as measured by words per minute, also was assessed for change with medication state. No significant group differences were found between medication conditions for the perceptual ratings, though marked changes occurred for individual speakers. Moreover, participants were found to speak at a significantly slower rate while on medications. Results are discussed in terms of speaker characteristics, the viability of the perceptual rating methodology, and the possible influence of cognitive functioning on speech rate.
In this response to commentaries, we revisit the two main arguments of our target article. Based on data drawn from a variety of research areas - vocal behavior in nonhuman primates, speech physiology and pathology, neurobiology of basal ganglia functions, motor skill learning, paleoanthropological concepts - the target article, first, suggests a two-stage model of the evolution of the crucial motor prerequisites of spoken language within the hominin lineage: (1) monosynaptic refinement of the projections of motor cortex to brainstem nuclei steering laryngeal muscles, and (2) subsequent "vocal-laryngeal elaboration" of cortico-basal ganglia circuits, driven by human-specific FOXP2 mutations. Second, as concerns the ontogenetic development of verbal communication, age-dependent interactions between the basal ganglia and their cortical targets are assumed to contribute to the time course of the acquisition of articulate speech. Whereas such a phylogenetic reorganization of cortico-striatal circuits must be considered a necessary prerequisite for ontogenetic speech acquisition, the 30 commentaries - addressing the whole range of data sources referred to - point at several further aspects of acoustic communication which have to be added to or integrated with the presented model. For example, the relationships between vocal tract movement sequencing - the focus of the target article - and rhythmical structures of movement organization, the connections between speech motor control and the central-auditory and central-visual systems, the impact of social factors upon the development of vocal behavior (in nonhuman primates and in our species), and the interactions of ontogenetic speech acquisition - based upon FOXP2-driven structural changes at the level of the basal ganglia - with preceding subvocal stages of acoustic communication as well as higher-order (cognitive) dimensions of phonological development. Most importantly, thus, several promising future research directions unfold from these contributions - accessible to clinical studies and functional imaging in our species as well as experimental investigations in nonhuman primates.
Voice deficits in Parkinson disease (PD) emerge early in the disease process, but do not improve with standard treatments targeting dopamine. Experimental work in the rat shows that severe and chronic unilateral nigrostriatal dopamine depletion with 6-OHDA results in decreased intensity, bandwidth, and complexity of ultrasonic vocalizations. However, it is unclear if mild/acute dopamine depletion, paralleling earlier stages of PD, results in vocalization deficits, or to what degree vocalization parameters are correlated with other dopamine-dependent indicators of lesion severity or percent of tyrosine hydroxylase (%TH) loss. Here, we assayed ultrasonic vocalizations, forelimb asymmetry, and apomorphine rotations in rats with a range of unilateral dopamine loss resulting from 6-OHDA or vehicle control infusions to the medial forebrain bundle at acute (72hours) and chronic (4 weeks) time points post-infusion. The %TH loss was evaluated at 4 weeks. At 72hours, forelimb asymmetry and %TH loss were significantly correlated, while at 4 weeks, all measures of lesion severity were significantly correlated with each other. Call complexity was significantly correlated with all measures of lesion severity at 72hours but only with %TH loss at 4 weeks. Bandwidth was correlated with forelimb asymmetry at both time points. Duration was significantly correlated with all dopamine depletion measures at 4 weeks. Notably, not all parameters were affected universally or equally across time. These results suggest that vocalization deficits may be a sensitive index of acute and catecholamine loss and further underscores the need to characterize the neural mechanisms underlying vocal deficits in PD.
Copyright © 2015. Published by Elsevier B.V.
The precise comparison of the voice characteristics of Parkinson disease (PD) patients with age-matched normal subjects is still one of the important research projects. The present study aimed at comparing the voice characteristics in sustained phonations of PD patients with an age-matched control group.
The subjects were 30 Japanese PD patients (15 males and 15 females). The control group consisted of 30 age-matched normal Japanese subjects (15 males and 15 females). Each subject was required to phonate into a mouthpiece attached to Vocal Function Analyzer (PS-77E; Nagashima Medical Instrumental Corporation, Tokyo, Japan) with the airway interruption system, and expiratory lung pressure, mean flow rate, fundamental frequency and intensity of voice, and pitch range were measured. Maximum phonation time was also assessed.
The highest pitch level was significantly lower in the PD group than that of the control group in both sexes, whereas the lowest pitch level was significantly higher in the PD group only in males. In both sexes, the pitch range was significantly narrower in the PD group than in the control group. There was no significant difference in intensity, mean flow rate, expiratory pressure, or maximum phonation time between the two groups, for both males and females.
Only remarkable difference in the voice characteristics between PD patients and age-matched normal elderlies was limited to the narrowing of the pitch range in PD patients. The restriction in pitch regulation in PD patients was considered to be because of difficulty in reciprocal control of the laryngeal muscles secondary to latent rigidity.
Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
Parkinson disease (PD) is a complex, progressive, neurodegenerative disorder that leads to a wide range of deficits including fine and gross sensorimotor impairment, autonomic dysfunction, mood disorders, and cognitive decline. Traditionally, the focus for diagnosis and treatment has been on sensorimotor impairment related to dopamine depletion. It is now widely recognized, however, that PD-related pathology affects multiple central nervous system neurotransmitters and pathways. Communication and swallowing functions can be impaired even in the early stages, significantly affecting health and quality of life. The purpose of this article is to review the literature on early intervention for communication and swallowing impairment in PD. Overarching themes were that (1) studies and interpretation of data from studies in early PD are limited; (2) best therapy practices have not been established, in part due to the heterogeneous nature of PD; and (3) as communication and swallowing problems are pervasive in PD, further treatment research is essential.
Background:
Rhythmic disturbances are a hallmark of motor speech disorders, in which the motor control deficits interfere with the outward flow of speech and by extension speech understanding. As the functions of rhythm are language-specific, breakdowns in rhythm should have language-specific consequences for communication.
Objective:
The goals of this paper are to (i) provide a review of the cognitive-linguistic role of rhythm in speech perception in a general sense and crosslinguistically; (ii) present new results of lexical segmentation challenges posed by different types of dysarthria in American English, and (iii) offer a framework for crosslinguistic considerations for speech rhythm disturbances in the diagnosis and treatment of communication disorders associated with motor speech disorders.
Summary:
This review presents theoretical and empirical reasons for considering speech rhythm as a critical component of communication deficits in motor speech disorders, and addresses the need for crosslinguistic research to explore language-universal versus language-specific aspects of motor speech disorders.
Purpose:
The purpose of the present study was to examine the effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and the caudal zona incerta (cZi) pitch characteristics of connected speech in patients with Parkinson's disease (PD).
Method:
The authors evaluated 16 patients preoperatively and 12 months after DBS surgery. Eight patients were implanted in the STN (ages 51-72 years; M = 63 years). Six received bilateral implantation and 2 unilateral (left) implantation. Eight patients were bilaterally implanted in the cZi (ages 49-71 years; M = 60.8 years). Preoperative assessments were made after a levodopa challenge (approximately 1.5 times the ordinary dose). All postoperative examinations were made off and on stimulation with a clinically optimized dose of levodopa. Measurements of pitch range and variability were obtained from each utterance in a recorded read speech passage.
Results:
Pitch range and coefficient of variation showed an increase in patients under STN-DBS. Patients under cZi-DBS showed no significant effects of treatment on investigated pitch properties.
Conclusion:
STN-DBS was shown to increase pitch variation and range. The results provided no evidence of cZi-DBS having a beneficial effect on PD patients' pitch variability.
Projects currently underway are generating thousands of publicly available DNA sequences representing numerous genes from plant parasitic nematodes. Use of these data has the potential to revolutionise gene discovery, as well as aiding in genome physical mapping and expression profiling experiments. This article introduces sequences called expressed sequence tags or ESTs, which are single-sequence reads from randomly-selected cDNA clones. We review the process used to create these sequences and outline the strengths and weaknesses of ESTs as research tools. Instructions on how to access and use EST data also are provided. Découverte rapide de gènes chez les nématodes parasites des plantes: le point sur l'utilisation des Etiquettes de Séquences Exprimées - Les projets actuellement en cours génèrent des milliers de séquences d'ADN, publiquement disponibles, représentant de nombreux gènes de nématodes parasites des plantes. L'utilisation de ces données pourrait révolutionner la découverte des gènes en facilitant aussi bien les expériences de cartographie physique que celles de profils d'expression. Cet article présente les séquences dérivées de clones d'ADNc sélectionnés au hasard, appelées étiquettes de séquences exprimées (ESTs). Nous exposons le processus utilisé pour les générer de même que les avantages et les inconvénients des ESTs comme outils de recherche. Les instructions concernant l'accès et l'utilisation des ESTs sont également fournies.
Levodopa (L-dopa) effects on the cardinal and axial symptoms of Parkinson's disease (PD) differ greatly, leading to therapeutic challenges for managing the disabilities in this patient's population. In this context, we studied the cerebral networks associated with the production of a unilateral hand movement, speech production, and a task combining both tasks in 12 individuals with PD, both off and on levodopa (L-dopa). Unilateral hand movements in the off medication state elicited brain activations in motor regions (primary motor cortex, supplementary motor area, premotor cortex, cerebellum), as well as additional areas (anterior cingulate, putamen, associative parietal areas); following L-dopa administration, the brain activation profile was globally reduced, highlighting activations in the parietal and posterior cingulate cortices. For the speech production task, brain activation patterns were similar with and without medication, including the orofacial primary motor cortex (M1), the primary somatosensory cortex and the cerebellar hemispheres bilaterally, as well as the left- premotor, anterior cingulate and supramarginal cortices. For the combined task off L-dopa, the cerebral activation profile was restricted to the right cerebellum (hand movement), reflecting the difficulty in performing two movements simultaneously in PD. Under L-dopa, the brain activation profile of the combined task involved a larger pattern, including additional fronto-parietal activations, without reaching the sum of the areas activated during the simple hand and speech tasks separately. Our results question both the role of the basal ganglia system in speech production and the modulation of task-dependent cerebral networks by dopaminergic treatment.
The initiation of genome projects on helminths of medical importance promises to yield new drug targets and vaccine
candidates in unprecedented numbers. In order to exploit this emerging data it is essential that the user community is
aware of the scope and quality of data available, and that the genome projects provide analyses of the raw data to highlight
potential genes of interest. Core bioinformatics support for the parasite genome projects has promoted these approaches.
In the Brugia genome project, a combination of expressed sequence tag sequencing from multiple cDNA libraries
representing the complete filarial nematode lifecycle, and comparative analysis of the sequence dataset, particularly using
the complete genome sequence of the model nematode C.
elegans, has proved very effective in gene discovery.
Speech and voice disorders are key elements in the diagnosis and management of individuals with Parkinson disease (PD). This chapter reviews the classic symptoms of speech and voice disorders in PD and their assessment. The complex origin of these disorders is described in relation to motor problems (hypokinesia/bradykinesia reflecting reduced muscle activation and abnormal scaling or maintenance of the gain of movement amplitude), sensory processing problems (abnormal gating of the somatosensory cortex, abnormal gating of the auditory cortex via feed-forward mechanisms, and abnormal perception of one's own voice), cueing problems (reflecting deficits in internal/implicit cueing), and neuropsychological problems (impaired attention to action, vocal vigilance, and self-regulation of vocal output). The impact of medical treatment (neuropharmacological, neurosurgical) on speech and voice is reviewed. Speech treatment is described with special emphasis on LSVT® LOUD, a scientifically tested, efficacious treatment consistent with principles that drive activity-dependent neural plasticity. The recommendation is made for early referral to a speech clinician for optimum management of speech and voice disorders in PD.
A cDNA encoding a nuclear hormone receptor of the steroid/thyroid receptor superfamily was obtained from third-stage larvae(L3) of the parasitic roundworm Strongyloides stercoralis. A recombinant clone was isolated via screening of an S. stercoralis cDNA library with a polymerase chain reaction (PCR)-generated probe. The insert of 2583 bp contained the complete coding
sequence of the receptor homologue. The conceptually translated amino acid sequence of this open reading frame encodes a 753-amino-acid-residue
protein with an apparent molecular weight of 83.6 kDa and a predicted isoelectric point (pI) of 8.52. The coding sequence
is 69% AT and the noncoding sequence is 72% AT, reflecting a characteristic A/T codon bias of S. stercoralis. In this report the amino acid sequence of the S. stercoralis nuclear hormone receptor of the steroid/thyroid receptor superfamily is compared with that of nuclear hormones of Caenorhabditis elegans, human orphan nuclear receptors, and insect ecdysone receptors. The potential role of steroids in the induction of hyperinfection
syndrome is also discussed.
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has proven effective in treating the major motor symptoms of advanced Parkinson's disease (PD). The aim of this study was to learn which laryngeal and articulatory acoustic features changed in patients who were reported to have worse speech with stimulation. Six volunteers with PD who had bilateral STN electrodes were recorded with DBS turned on or off. Perceptual ratings reflected poorer speech performance with DBS on. Acoustic measures of articulation (corner vowel formants, diphthong slopes, and a spirantization index) and phonation (perturbation, long-term average spectrum) as well as verbal fluency scores showed mixed results with DBS. Some speakers improved while others became worse on individual measures. The magnitude of DBS effects was not predictable based on the patients' demographic characteristics. Future research involving adjustments to stimulator settings or electrode placement may be beneficial in limiting the negative effects of DBS on speech.
According to the U.S. National Institutes of Health, approximately 500,000 Americans have Parkinson's disease (PD), with roughly another 50,000 receiving new diagnoses each year. 70%-90% of these people also have the hypokinetic dysarthria associated with PD. Deep brain stimulation (DBS) substantially relieves motor symptoms in advanced-stage patients for whom medication produces disabling dyskinesias. This study investigated speech changes as a result of DBS settings chosen to maximize motor performance. The speech of 10 PD patients and 12 normal controls was analyzed for syllable rate and variability, syllable length patterning, vowel fraction, voice-onset time variability, and spirantization. These were normalized by the controls' standard deviation to represent distance from normal and combined into a composite measure. Results show that DBS settings relieving motor symptoms can improve speech, making it up to three standard deviations closer to normal. However, the clinically motivated settings evaluated here show greater capacity to impair, rather than improve, speech. A feedback device developed from these findings could be useful to clinicians adjusting DBS parameters, as a means for ensuring they do not unwittingly choose DBS settings which impair patients' communication.
This study examines the impact of Parkinson's disease (PD) on communicative efficiency conveyed through prosody. A new assessment method for evaluating productive prosodic skills in Dutch speaking dysarthric patients was devised and tested on 36 individuals (18 controls, 18 PD patients). Three professional listeners judged the intended meanings in four communicative functions of Dutch prosody: Boundary Marking, Focus, Sentence Typing, and Emotional Prosody. Each function was tested through reading and imitation. Interrater agreement was calculated. Results indicated that healthy speakers, compared to PD patients, performed significantly better on imitation of Boundary Marking, Focus, and Sentence Typing. PD patients with a moderate or severe dysarthria performed significantly worse on imitation of Focus than on reading of Focus. No significant differences were found for Emotional Prosody. Judges agreed well on all tasks except Emotional Prosody. Future research will focus on elaborating the assessment and on developing a therapy programme paralleling the assessment.
Former studies on the effects of physical exercise, physical and occupational therapy (PT, OT) and speech and swallowing therapy (ST, SwT) in Parkinson's disease (PD) have demonstrated little or uncertain effects. New pathophysiological concepts have been developed. Recent controlled high-level studies demonstrate improvement of mobility and balance after training of muscular strength and endurance, trunk control, and amplitude and rhythmicity of movements (treadmill). Attentional and cognitive strategies were found to enforce body awareness and improve movement sequences. Dance, sensory (auditory, visual, tactile) and cognitive cueing are effective for problems of gait and balance. Whether PT and OT reduce the risk of falls remains uncertain. ST including Lee Silverman Voice Treatment has been shown to relieve speech problems. SwT and OT are frequently applied, however, further studies are necessary. Therapeutic interventions need to be evaluated with regard to consistency, intensity, frequency, duration, side effects, home versus institution based and standardized versus individualized training, quality standards, practicability in real life, and cost-effectiveness. Parkinson patients should resume or continue physical exercise as long as possible. There is hope that regular sport may modify PD risk and progression.
Speaking, which naturally occurs in different modes or "tasks" such as conversation and repetition, relies on intact basal ganglia nuclei. Recent studies suggest that voice and fluency parameters are differentially affected by speech task. In this study, the authors examine the effects of subcortical functionality on voice and fluency, comparing measures obtained from spontaneous and matched repeated speech samples.
Subjects with Parkinson's disease who were being treated with bilateral deep brain stimulation (DBS) of the subthalamic nuclei were tested with stimulators ON and OFF.
The study found that a voice measure, harmonic to noise ratio, is improved in repetition and in the DBS-ON condition and that dysfluencies are more plentiful in conversation with little or variable influence of DBS condition.
These findings suggest that voice and fluency are differentially affected by DBS treatment and that task conditions, interacting with subcortical functionality, influence motor speech performance.
Previous research has indicated that in Parkinson's disease (PD) some motor speech characteristics are changed by levodopa administration, while others are not. In advanced PD, the time course of these changes and the correlations with motor performance have not been sufficiently investigated. The purpose was to investigate the sequential changes of respiratory, articulatory, and phonatory speech characteristics across a levodopa drug cycle, using spirometry, acoustic, and motor speech analysis. Seven patients with advanced PD were included. All patients were evaluated sequentually at 15 minute intervals before and following levodopa intake. Data were analysed using repeated measures ANOVA and non-parametric analysis. Significant changes were found in motor function, vital capacity, and standard deviation of the diadochokinetic period. A trend was present for shimmer and frequency of the first formant. Significant inter-individual differences in the sequential changes were demonstrated for nearly all evaluated parameters. The conclusion is that, in advanced PD, the evaluation of speech characteristics at one moment after levodopa administration is not representative of an entire drug cycle and that an individualized evaluation of an entire drug cycle is warranted before initiation of a speech-language pathology program.
While the beneficial effect of levodopa on motor impairment in Parkinson's disease (PD) has been well documented, its effect on speech has rarely been examined and the respective literature is inconclusive. The aim of our study was to analyze the effect of short-term levodopa admission and long-term dopaminergic treatment on speech in PD patients in early stages of the disease. Motor examination according to UPDRS III and speech testing were performed in 23 PD patients (9 males; median age 68, 42-78 years) in the early morning after having abstained from dopaminergic medication overnight ("off" state, t0) after administration of 200 mg of soluble levodopa (t1), and at follow-up after 12-14 weeks under stable dopaminergic medication (t2). Speech examination comprised the perceptual rating of global speech performance and an acoustical analysis based upon a standardized reading task. While UPDRS III showed a significant amelioration after L: -dopa application, none of the parameters of phonation, intonation, articulation and speech velocity improved significantly in the "on" state, neither under short-term levodopa administration (t1) nor on stable dopaminergic treatment (t2). However, there was a positive effect of dopaminergic stimulation on vowel articulation in individual patients. Results indicated significant beneficial effect of short-term levodopa administration or long-term dopaminergic medication on different dimensions of speech in PD patients. As some improvement of vowel articulation was seen in individual patients, the pre-existing pattern of speech impairment might be responsible for the different response to pharmacological treatment.
Dysprosody is a common feature in speakers with hypokinetic dysarthria. However, speech prosody varies across different types of speech materials. This raises the question of what is the most appropriate speech material for the evaluation of dysprosody.
To characterize the prosodic impairment in Cantonese speakers with hypokinetic dysarthria associated with Parkinson's disease, and to determine the effect of different types of speech stimuli on the perceptual rating of prosody.
Speech data in the form of sentence reading, passage reading, and monologue were collected from ten Cantonese speakers with Parkinson's disease. Perceptual analysis was conducted on ten prosodic parameters to evaluate five dimensions of prosody, based on a theoretical framework: pitch, loudness, duration, voice quality, and degree of reduction.
The results showed that the most severely affected prosodic parameters were monopitch, harsh voice, and monoloudness, followed by breathy voice and prolonged interval. Differences were noted between speakers with mild and moderate dysprosody. No statistically significant differences were found between the three types of stimuli. However, qualitative analysis revealed noticeable differences between the three stimuli in two speakers.
The prosodic profile of Cantonese speakers with hypokinetic dysarthria is similar to those of other languages (for example, English). The involvement of two new dimensions in the definition of prosody (voice quality and degree of reduction) provides additional insight in differentiating patients with mild and moderate dysarthria. Further investigation on the use of speech materials in the clinical evaluation of speech prosody in speakers with dysarthria is needed, as no single task was found to represent a patient's performance under all circumstances.
Even though the mesocortical dopamine system is known to play an important role in affect control and reward related behaviour, only little is known about the impact of Parkinson's disease on emotional communication. The ability to perceive and express emotions via speech plays an essential role in every day social life. Here, studies investigating perception and production of emotional prosody in Parkinson's disease will be reviewed and own results will be presented. Evidence will be provided that patients with Parkinson's disease do have changes of emotional prosody processing and that they also show alterations of emotional speech production. Together, these studies highlight the importance of the basal ganglia and their connections for emotional communication.
LSVT LOUD (Lee Silverman Voice Treatment) is efficacious in the treatment of speech disorders in idiopathic Parkinson's disease (IPD), particularly hypophonia. Functional imaging in patients with IPD has shown abnormalities in several speech regions and changes in these areas immediately following treatment. This study serves to extend the analysis by correlating changes of regional neural activity with the main behavioral change following treatment, namely, increased vocal intensity. Ten IPD participants with hypophonia were studied before and after LSVT LOUD. Cerebral blood flow during rest and reading conditions were measured by H(2)(15)O-positron emission tomography. Z-score images were generated by contrasting reading with rest conditions for pre- and post-LSVT LOUD sessions. Neuronal activity during reading in the pre- versus post-LSVT LOUD contrast was correlated with corresponding change in vocal intensity to generate correlation images. Behaviorally, vocal intensity for speech tasks increased significantly after LSVT LOUD. The contrast and correlation analyses indicate a treatment-dependent shift to the right hemisphere with modification in the speech motor regions as well as in prefrontal and temporal areas. We interpret the modification of activity in these regions to be a top-down effect of LSVT LOUD. The absence of an effect of LSVT LOUD on the basal ganglion supports this argument. Our findings indicate that the therapeutic effect of LSVT LOUD in IPD hypophonia results from a shift in cortical activity to the right hemisphere. These findings demonstrate that the short-term changes in the speech motor and multimodal integration areas can occur in a top-down manner.
Parasitic nematodes of the genus Strongyloides are remarkable for their ability to switch between alternative free-living developmental pathways in response to changing internal environmental conditions. After exiting the host, soil-dwelling larval stages may develop either to infectivity via 2 microbiverous stages (homogonic development) or to free-living adulthood via 4 microbiverous larval stages (heterogonic development). The progeny of these adults then give rise to the infective stage. In the latter case, free-living existence is extended in time and the number of infective larvae is greatly amplified. Anterior chemosensory neurons (amphidial neurons) are thought to respond to environmental cues and via signal transduction pathways control the direction of larval development. We now demonstrate by laser microbeam ablation that 2 classes of amphidial neurons (ASF and ASI), acting together, control the direction of free-living larval development. Larvae in which the neurons were killed developed to infectivity via the homogonic route rather than to adulthood via the otherwise predominant heterogonic route. These neurons are probable homologues of neurons ADF (=ASF) and ASI in Caenorhabditis elegans, suggesting the control of development at the cellular level is conserved among divergent taxa of nematodes. These observations also have important implications for the evolution of nematode parasitism and the design of new prophylactic measures against parasitic nematodes of medical and veterinary medical importance.
Using degenerate oligonucleotide primers based on conserved active site residues, we have isolated a cDNA encoding an aspartic protease from the nematode parasite Strongyloides stercoralis, an important, enteric pathogen of humans. cDNAs encoding the aspartic protease were isolated from the infective, third stage larvae of the parasite as well as from free-living, rhabditiform larvae. Based on comparisons of other aspartic proteases, the cDNA encoded a short signal peptide, an enzyme pro-segment of 35 amino acid residues, and mature enzyme of 337 residues. Homology alignments using the proenzyme sequence showed that the novel S. stercoralis zymogen was 36% identical to human pepsinogen A and 36% identical to pepsinogen C (progastricin) from humans and macaques. Phylogenetic analyses using the Phylip program and analysis of Glx/Asx and Leu/Ile ratios indicated that the proenzyme was closely related to pepsinogen A-like enzymes from the free-living nematode Caenorhabditis elegans and Haemonchous contortus, a nematode parasite of the gastro-intestinal tract of sheep. We have termed this novel enzyme strongyloidespepsin.
Here we report 658 expressed sequence tags (ESTs) generated from the 5'-termini of clones randomly selected from directional cDNA libraries constructed from mRNAs from three developmental stages of Schistosoma japonicum. Putative identifications were assigned to 46. 2% of the ESTs; 6.4% were previously known from S. japonicum, 5.6% were previously known from S. mansoni, 34.2% were known from other organisms, and the remaining 53.8% may represent S. japonicum-specific genes. These 658 ESTs appeared to be derived from 457 unique genes, which together represent 2 to 3% of the 15,000 to 20,000 genes predicted to occur in the schistosome genome.
Caenorhabditis elegans is a rhabditid nematode. What relevance does this have for the interpretation of the complete genome sequence, and how will it affect the exploitation of the sequence for scientific and social ends? Nematodes are only distantly related to humans and other animal groups; will this limit the universality of the C. elegans story? Many nematodes are parasites; can knowledge of the C. elegans sequence aid in the prevention and treatment of disease?
A cDNA encoding a nuclear hormone receptor of the steroid/thyroid receptor superfamily was obtained from third-stage larvae(L3) of the parasitic roundworm Strongyloides stercoralis. A recombinant clone was isolated via screening of an S. stercoralis cDNA library with a polymerase chain reaction (PCR)-generated probe. The insert of 2,583 bp contained the complete coding sequence of the receptor homologue. The conceptually translated amino acid sequence of this open reading frame encodes a 753-amino-acid-residue protein with an apparent molecular weight of 83.6 kDa and a predicted isoelectric point (pI) of 8.52. The coding sequence is 69% AT and the noncoding sequence is 72% AT, reflecting a characteristic A/T codon bias of S. stercoralis. In this report the amino acid sequence of the S. stercoralis nuclear hormone receptor of the steroid/thyroid receptor superfamily is compared with that of nuclear hormones of Caenorhabditis elegans, human orphan nuclear receptors, and insect ecdysone receptors. The potential role of steroids in the induction of hyperinfection syndrome is also discussed.
A full length cDNA encoding the highly immunodominant 41 kDa antigen of Strongyloides stercoralis (P5), recognized by 83% of human patients [Siddiqui et al. (1997) Parasitol Res 83:655-658], is obtained. A clone containing a 1371 bp insert was selected following screening of the S. stercoralis cDNA library with antibodies specific to antigen P5. The nucleotide sequence of this insert identified a cDNA coding for the gamma-subunit of isocitrate dehydrogenase (NAD+), GenBank Accession Number AF176568. The conceptually translated amino acid sequence of the open reading frame for the gamma-subunit of S. stercoralis isocitrate dehydrogenase (NAD+) encodes a 388 amino acid residue protein with an apparent molecular weight of 43 kDa and a predicted pI of 7.15. The sequence is 71% A/T, reflecting the characteristic A/T codon bias of S. stercoralis. The amino acid sequence of the S. stercoralis gamma-subunit of isocitrate dehydrogenase (NAD+) is compared with those of Caenorhabditis elegans, rat and human NAD(+)-ICDH. The diagnostic potential of the S. stercoralis gamma-subunit of isocitrate dehydrogenase (NAD+) is also discussed.
C-type lectins (C-TLs) are a family of carbohydrate-binding proteins intimately involved in diverse processes including vertebrate immune cell signalling and trafficking, activation of innate immunity in both vertebrates and invertebrates, and venom-induced haemostasis. Helminth C-TLs sharing sequence and structural similarity with mammalian immune cell lectins have recently been identified from nematode parasites, suggesting clear roles for these proteins at the host-parasite interface, notably in immune evasion. Here, Alex Loukas and Rick Maizels review the status of helminth lectin research and suggest ways in which parasitic worms might utilize C-TLs during their life history.
A full length cDNA (1463 bp) encoding isocitrate lyase (EC 4.1.3.1) of Strongyloides stercoralis is described. The nucleotide sequence of this insert identified a cDNA coding for the isocitrate lyase. The conceptually translated amino acid sequence of the open reading frame for S. stercoralis isocitrate lyase encodes a 450 amino acid residue protein with an apparent molecular weight of 50 kDa and a predicted pl of 6.39. The sequence is 69% A/T, reflecting a characteristic A/T codon bias of S. stercoralis. The amino acid sequence of S. stercoralis isocitrate lyase is compared with bifunctional glyoxylate cycle protein of Caenorhabditis elegans and isocitrate lyases from Chlamydomonas reinhardtii and Myxococcus xanthus. The full length cDNA of S. stercoralis was expressed in pRSET vector and bacteriophage T7 promoter based expression system. S. stercoralis lyase recombinant protein, purified via immobilized metal affinity chromatography, showed a molecular mass of 50 kDa on polyacrylamide gels. The role of isocitrate lyase in the glyoxylate cycle and energy metabolism of S. stercoralis is also discussed.
Two G protein alpha subunit genes orthologous to gpa-2 and gpa-3 in Caenorhabditis elegans have been identified in the parasitic nematode, Strongyloides stercoralis. These genes mediate chemosensory signal transduction regulating dauer arrest in C. elegans. In the parasite, they represent candidate mediators for regulation of the choice between free-living and parasitic life cycles, the obligatory developmental arrest of infective larvae, and reactivation of development after infection. The (A+T) content of these genes is 72.2% for coding sequences, 90% for introns, and 84.1% for 5' and 3' flanking regions, requiring the use of low extension temperatures for long distance PCR. The possible significance of conserved structural motifs of these proteins is discussed.
A full length cDNA encoding an IgG immunoreactive antigen of Strongyloides stercoralis is described. A clone containing 1,328 bp insert was selected following screening of S. stercoralis cDNA library with an IgG fraction obtained from a pool of 78 S. stercoralis positive human sera samples. The nucleotide sequence of the 1,328 bp insert was found to be 70.5% A/T, reflecting a characteristic A/T codon bias of S. stercoralis. The nucleotide sequence of this insert identified a cDNA coding for a zinc finger protein. The conceptually translated amino acid sequence of the open reading frame for the IgG immunoreactive antigen of S. stercoralis encodes a 211 amino acid residue protein with an apparent molecular weight of 22.8 kDa and a predicted isoelectric point of 8.71. The diagnostic potential of this IgG immunoreactive antigen of S. stercoralis is also discussed.
To advance and facilitate molecular studies of Brugia malayi, one of the causative agents of human lymphatic filariasis, an expressed sequence tag (EST)-based gene discovery programme has been carried out. Over 22,000 ESTs have been produced and deposited in the public databases by a consortium of laboratories from endemic and non-endemic countries. The ESTs have been analysed using custom informatic tools to reveal patterns of individual gene expression that may point to potential targets for future research on anti-filarial drugs and vaccines. Many genes first discovered as ESTs are now being analysed by researchers for immunodiagnostic, vaccine and drug target potential. Building on the success of the B. malayi EST programme, significant EST datasets are being generated for a number of other major parasites of humans and domesticated animals, and model parasitic species.
A new approach to rapid sequence comparison, basic local alignment search tool (BLAST), directly approximates alignments that optimize a measure of local similarity, the maximal segment pair (MSP) score. Recent mathematical results on the stochastic properties of MSP scores allow an analysis of the performance of this method as well as the statistical significance of alignments it generates. The basic algorithm is simple and robust; it can be implemented in a number of ways and applied in a variety of contexts including straightforward DNA and protein sequence database searches, motif searches, gene identification searches, and in the analysis of multiple regions of similarity in long DNA sequences. In addition to its flexibility and tractability to mathematical analysis, BLAST is an order of magnitude faster than existing sequence comparison tools of comparable sensitivity.
The genetic code is degenerate, but alternative synonymous codons are generally not used with equal frequency. Since the pioneering work of Grantham'a group (1, 2) it has been apparent that genes from one species often share similarities incodon frequency; under the “genome hypothesis” (1, 2) there is a species-specific pattern to codon usage.
However, it has become clear that in most species there are also considerable differences among genes (3–7). Multivariate analyses have revealed that in each species so far examined there is a single major trend in codon usage among genes, usually from highly biased to more nearly even usage of synonymous codons. Thus, to represent the codon usage pattern of an organism it is not sufficient to sum over all genes (8), as this conceals the underlying heterogeneity. Rather, it is necessary to describe the trend among genes seen in that species. We illustrate these trends for six species where codon usage has been examined in detail, by presenting the pooled codon usage for the 10% of genes at either end of the major trend (Table 1).
Closely-related organisms have similar patterns of codon usage, and so the six species in Table 1 are representative of wider groups. For example, with respect to codon usage, Salmonella typhimurlum closely resembles E. coli (9), while all mammalian species so far examined (principally mouse, rat and cow) largely resemble humans (4, 8).
The voices of patients suffering from Parkinson's disease change in various ways. This paper sets out to examine the effect of these changes on the impressions made on listeners, and to try to see what vocalic and prosodic features account for these impressions. Tape recordings from segments of interviews with 4 patients, and 4 control subjects with ischaemic heart disease, were played to 16 naive listeners. These listeners were asked to rate their impressions of these voices on 15 dimensions of personality. There were significant differences on most of the dimensions, despite the fact that there were no differences between the two groups on such scales as Beck's depression inventory and the mood adjective check list. The parkinsonian patients were seen to be cold, withdrawn and anxious, not to relate well to the interviewer and to be enjoying the interview less than the controls. These ratings are very similar to those previously reported for the same patients, using silent video recordings only. The voice recordings were analysed along various dimensions of prosody. The factors which were different between the groups included the frequency and type of pauses in speech and the range or variability of the fundamental frequency. The implications of this exploratory study for intervention are discussed.
The speech defect in 18 patients with Parkinson’s syndrome is described. Various forms of therapy including levodopa were evaluated in a double-blind crossover manner. Levodopa was superior to placebo and a commonly used antiparkinsonian drug (procyclidine hydrochloride) in improving speech intelligibility. Labial movement tracings showed that this improvement was mainly the result of a shorter latency between initiation of labial movement and speech and increased speed and symmetry of labial activity. Oral exercises showed that levodopa caused enhanced labial motility at the corners and lower part of the mouth. The general improvement in bradykinesia and rigidity derived from levodopa therapy may also influence the improvement in the articulation of a parkinsonian patient.
Fatal disseminated disease was induced in ten patas monkeys infected with two Southeast Asian strains of Strongyloides stercoralis. While some animals died within 6 weeks after infection, others controlled their infections until placed on high doses of corticosteroids. Larvae were first noted in the stools 11-20 days after transcutaneous exposure to filariform larvae. Daily larval counts tended to increase as the infections progressed, but the number of larvae in the stool was not predictive of whether a monkey would control his infection or succumb to fatal disease. Hyperinfection was confirmed in the six monkeys in which counts were made of the adult female parasites in the duodenum at postmortem, as well as by pathologic findings in all animals. Clinical signs of disease were vague until dyspnea induced by terminal pulmonary hemorrhage occurred. Eosinophilia and/or basophilia were noted intermittently in some infections. Severe necrotizing duodenitis, colitis, and pulmonary hemorrhage were the most conspicuous postmortem findings. Hyperinfection has been predictably induced in a cercopithecoid monkey for the first time; a species which may lend itself to further investigations into the pathogenesis of disseminated strongyloidiasis .
The use of cDNA libraries has become increasingly widespread as new techniques for library construction and analysis have become available. In recent years, interest in cell-type or stage-specific gene expression has necessitated the construction of cDNA libraries from very small numbers of cells. Recent advances in techniques of RNA isolation, cDNA synthesis, library construction, and the use of the polymerase chain reaction have made this a realistic goal.
The entire 1766 bases of the 18S rRNA gene of Strongyloides stercoralis have been sequenced. The gene has a 38% G+C content. Although it is similar in length to the 18S rRNA gene of Caenorhabditis elegans, the only other completely sequenced nematode 18S rRNA gene, it is only 69% identical. Closely related helminths will need to be sequenced in order to delineate sequences specific for the diagnosis of strongyloidiasis.
In order to isolate proteinase genes from parasitic nematodes by polymerase chain reaction (PCR) techniques, we employed a pair of consensus oligonucleotide primers designed to anneal to the active site cysteine (primer ncpC) and asparagine (primer ncpN) coding regions of cysteine proteinases. The primers were biased toward the nucleotide and codon usages of cysteine proteinase genes of nematodes and were based on the consensus nucleotide sequences flanking the active site residues of genes from Haemonchus contortus, Caenorhabditis elegans, and Ostertagia ostertagi. We employed 'touchdown' PCR conditions and were able to amplify novel cysteine proteinase gene fragments from the rodent parasite Strongyloides ratti, the human pathogen S. stercoralis, the canine hookworm Ancylostoma caninum, and from C. elegans. These clones are gene homologs of cathepsin B-like (lysosomal associated) proteases and will facilitate screening of both cDNA and genomic DNA libraries.