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W C Smith

Publications and source records attributed to W C Smith.

At least 19 recordsLinked to original sources
PubMed2003

Delay in presentation in the context of local knowledge and attitude towards leprosy--the results of qualitative fieldwork in Paraguay.

OBJECTIVE: The primary objective of our research was to explore help-seeking behavior in the context of knowledge, attitude, and practice as factors contributing to delay in presentation in leprosy. The secondary objective was to demonstrate the value of basic qualitative research methods in this context. METHODOLOGY: Fieldwork was based at the Hospital Mennonita Km 81, the referral center for leprosy services in Paraguay. We adopted exclusively qualitative methods for fieldwork, effectively carrying out a rapid assessment of factors contributing to delay. We relied on multiple sources of information and the use of multiple methods to ensure the validity of our findings. RESULTS: Our findings linked delay in presentation to traditional beliefs, lack of awareness of the early symptoms of leprosy, stigma, seeking help from natural healers, and to interactions with the health services. Traditional beliefs diminish the importance of the early symptoms of leprosy. Stigma has an impact on decisions to seek help. Natural healers have maintained their traditional status in society; their preferred treatments for leprosy are ineffective. Only rarely do natural healers refer to the health services. Once presented to the health services, some individuals affected by leprosy experienced lengthy delays in diagnosis and start of treatment. DISCUSSION: To address the traditional values of a society and provide effective public health initiatives is a clearly a major challenge for program organizers and for health education. Increased awareness of leprosy and sensitivity to its social consequences among health service practitioners is a further priority.

Attitude to Health↗
PubMed2002

The course of chronic pain in the community: results of a 4-year follow-up study.

Little is known about the course of chronic pain in the community. Such information is needed for the prevention and management of chronic pain. We undertook a 4-year follow-up study of 2184 individuals living in Grampian, UK to describe patterns and predictors of change in chronic pain over time. In October 2000, participants completed a postal questionnaire including case definition questions, the chronic pain grade questionnaire, the SF-36 and socio-demographic questions. Information from this questionnaire was compared to information collected from a similar questionnaire in 1996. A response rate of 83% was achieved for the follow-up study. The overall prevalence of chronic pain (pain or discomfort present either all the time or on and off for 3 months or longer) increased from 45.5% at baseline to 53.8% at follow-up. Seventy-nine percent of those with chronic pain at baseline still had it at follow-up. The average annual incidence was 8.3% and the average annual recovery rate was 5.4%. Individuals in the study samples who are in lowest quartile of SF-36 domains--physical functioning, social functioning and bodily pain at baseline--were more likely to develop chronic pain at follow-up, and respondents who were retired were less likely to develop chronic pain. Individuals in the study samples in the lowest quartile of SF-36 domains, bodily pain and general health at baseline, were less likely to recover from their chronic pain, as were those aged 45-74 compared with those aged 25-34. We concluded that chronic pain is a common, persistent problem in the community with relatively high incidence and low recovery rates. The lack of association between onset or recovery from chronic pain and most traditional socio-demographic factors, highlights the need to broaden the range of factors included in studies of chronic pain aetiology.

Adult↗
PubMed2001

Developmental genetics in primitive chordates.

Recent advances in the study of the genetics and genomics of urochordates testify to a renewed interest in this chordate subphylum, believed to be the most primitive extant chordate relatives of the vertebrates. In addition to their primitive nature, many features of their reproduction and early development make the urochordates ideal model chordates for developmental genetics. Many urochordates spawn large numbers of transparent and externally developing embryos on a daily basis. Additionally, the embryos have a defined and well-characterized cell lineage until the end of gastrulation. Furthermore, the genomes of the urochordates have been estimated to be only 5-10% of the size of the vertebrates and to have fewer genes and less genetic redundancy than vertebrates. Genetic screens, which are powerful tools for investigating developmental mechanisms, have recently become feasible due to new culturing techniques in ascidians. Because hermaphrodite ascidians are able to self-fertilize, recessive mutations can be detected in a single generation. Several recent studies have demonstrated the feasibility of applying modern genetic techniques to the study of ascidian biology.

Animals↗
PubMed2001

Boundaries and functional domains in the animal/vegetal axis of Xenopus gastrula mesoderm.

Patterning of the Xenopus gastrula marginal zone in the axis running equatorially from the Spemann organizer-the so--called "dorsal/ventral axis"--has been extensively studied. It is now evident that patterning in the animal/vegetal axis also needs to be taken into consideration. We have shown that an animal/vegetal pattern is apparent in the marginal zone by midgastrulation in the polarized expression domains of Xenopus brachyury (Xbra) and Xenopus nodal-related factor 2 (Xnr2). In this report, we have followed cells expressing Xbra in the presumptive trunk and tail at the gastrula stage, and find that they fate to presumptive somite, but not to ventrolateral mesoderm of the tailbud embryo. From this, we speculate that the boundary between the Xbra- and Xnr2-expressing cells at gastrula corresponds to a future tissue boundary. In further experiments, we show that the level of mitogen-activated protein kinase (MAPK) activation is polarized along the animal/vegetal axis, with the Xnr2-expressing cells in the vegetal marginal zone having no detectable activated MAPK. We show that inhibition of MAPK activation in Xenopus animal caps results in the conversion of Xnr2 from a dorsal mesoderm inducer to a ventral mesoderm inducer, supporting a role for Xnr2 in induction of ventral mesoderm.

Actins↗
PubMed2001

Immunocytochemical localization of opsin, visual arrestin, myosin III, and calmodulin in Limulus lateral eye retinular cells and ventral photoreceptors.

The photoreceptors of the horseshoe crab Limulus polyphemus are classical preparations for studies of the photoresponse and its modulation by circadian clocks. An extensive literature details their physiology and ultrastructure, but relatively little is known about their biochemical organization largely because of a lack of antibodies specific for Limulus photoreceptor proteins. We developed antibodies directed against Limulus opsin, visual arrestin, and myosin III, and we have used them to examine the distributions of these proteins in the Limulus visual system. We also used a commercial antibody to examine the distribution of calmodulin in Limulus photoreceptors. Fixed frozen sections of lateral eye were examined with conventional fluorescence microscopy; ventral photoreceptors were studied with confocal microscopy. Opsin, visual arrestin, myosin III, and calmodulin are all concentrated at the photosensitive rhabdomeral membrane, which is consistent with their participation in the photoresponse. Opsin and visual arrestin, but not myosin III or calmodulin, are also concentrated in extra-rhabdomeral vesicles thought to contain internalized rhabdomeral membrane. In addition, visual arrestin and myosin III were found widely distributed in the cytosol of photoreceptors, suggesting that they have functions in addition to their roles in phototransduction. Our results both clarify and raise new questions about the functions of opsin, visual arrestin, myosin III, and calmodulin in photoreceptors and set the stage for future studies of the impact of light and clock signals on the structure and function of photoreceptors.

Animals↗
PubMed2001

A sensitive chemiluminescent enzyme immunoassay for the bioanalysis of carboxyl-terminal B-chain analogues of human insulin.

Quantification of analogues of human insulin in biological matrices is complicated by differences in their immunoreactivity and the presence of both the analogue and endogenous concentrations of insulin in test samples. To facilitate pharmacokinetic comparisons of carboxyl-terminal B-chain analogues of human insulin, we undertook development of a sensitive ELISA. The ELISA detection method was optimized systematically to permit routine analysis of 10-microl serum samples. Accordingly, a noncompetitive 'sandwich' chemiluminescent ELISA was validated for the quantification of carboxyl-terminal B-chain insulin analogues in human serum over a concentration range from 5 to 3125 pM. The mean bias (RE%) within the validated range varied from -10.3 to 4.3%, with an intermediate precision (inter-assay CV%) from 4.2 to 11.5%. The two-sided 90% expectation tolerance interval for total measurement error was within +/-25% of the nominal concentration for all levels of validation samples. Insulin lispro, human insulin, proinsulin, despentapeptide insulin (DPI) and porcine insulin displayed comparable crossreactivity in the ELISA. Potential utility of the new assay for insulin bioanalysis in nonhuman species was investigated by assessing the pharmacokinetic profile of DPI in rats following administration of a single subcutaneous dose. The sensitive chemiluminescent detection method is simple to perform and should be readily adaptable for ELISAs of other therapeutic proteins.

Animals↗
PubMed2001

Chronic pain and quality of life following open inguinal hernia repair.

BACKGROUND: The aim was to determine the frequency and characteristics of chronic pain following open inguinal hernia repair and to identify risk factors for its development. METHODS: This was a questionnaire survey of a historical cohort of patients who underwent inguinal hernia surgery in Aberdeen. The sample comprised all patients (n = 351) who underwent surgery between January 1995 and December 1997, and who were alive and resident in Grampian in October 1999. Outcome measures included self-report of pain persisting for more than 3 months after operation. Pain was characterized by means of the McGill Pain Questionnaire, and quality of life was assessed with the Short Form 36 (SF-36). RESULTS: A total of 226 patients (64 per cent) completed the questionnaire, 67 (30 per cent) of whom reported chronic pain. Reported pain was predominantly neuropathic in character. Patients at increased risk of chronic pain were under 40 years old (P < 0.001), had day-case surgery (P = 0.004), had subsequent surgery on the same side (P < 0.005) and recalled pain before operation (P = 0.005). The SF-36 scores were significantly different in the social functioning, mental health and pain dimensions in patients with chronic pain. CONCLUSION: Chronic pain occurred in 30 per cent of patients after open hernia repair, a higher frequency than has been reported previously. Several risk factors were identified and further prospective research is recommended.

Adult↗
PubMed2001

The Level of Expressed Need--a measure of help-seeking behaviour for chronic pain in the community.

Chronic pain is a common and disabling condition, with a high impact on health and the health services in the community. The extent of help-seeking behaviour and factors that influence this are complex, but poorly understood. A simple, valid measure of help-seeking behaviour would be useful for community-based research, with a view to developing and evaluating interventions. The aims of the study were to test a hierarchical scale designed to measure help-seeking behaviour in chronic pain in postal surveys of the community, and to explore factors associated with responses. As part of a community survey of chronic pain, we developed the Level of Expressed Need (LEN) scale, based on questions about the use of treatment and professional advice for chronic pain. We compared this scale with two measures of chronic pain severity--the Chronic Pain Grade (CPG), and the Glasgow Pain Questionnaire (GPQ)--and analyzed associations with the SF36 general health questionnaire and demographic variables. Of 3605 respondents (corrected response rate 82%), 1817 reported chronic pain. Of these, 17% were at the mildest and 28% at the severest LEN. There were strong correlations with both the CPG (r=0.48) and the GPQ (r=0.55). There were, however, many important disparities in responses to these measures. Several other factors were independently associated with a high LEN in chronic pain: female gender, lower educational level, and physical, mental, pain and general health dimensions of the SF36 questionnaire. The LEN is a useful tool for measuring the help-seeking response to chronic pain in the general population. The findings confirm that this response is influenced by clinical and demographic factors in addition to the severity of the pain. Further development work will strengthen the instrument to explore these.

Adult↗
PubMed2001

The impact of chronic pain in the community.

BACKGROUND: Chronic pain is known to be very common in the community. Less is known about the epidemiology of more significant or severe chronic pain. The impact of chronic pain in the community, in terms of general health, employment and interference with daily activity, has not been quantified. OBJECTIVES: The aim of this study was to describe the prevalence and distribution in the community of chronic pain defined as 'significant' and 'severe', and to explore the impact of chronic pain on health and activity. METHODS: A questionnaire survey was carried out of a sample drawn from the general population in the Grampian region of SCOTLAND: Questionnaires were sent to a random sample of 4611 individuals aged 25 years and over, stratified for age and gender, selected from the practice lists of 29 general practices (total practice population 136,383). The study instrument included a case definition questionnaire, from which were identified individuals with 'any chronic pain' (pain of at least 3 months duration). The instrument also included a level of expressed need questionnaire and the chronic pain grade questionnaire, from which were derived definitions for 'significant chronic pain' (based on the reported need for treatment and professional advice) and 'severe chronic pain' (based on reported intensity and pain-related disability). The SF-36 general health questionnaire and demographic questions were also included. RESULTS: Of the sample, 14.1% reported 'significant chronic pain', and this was more prevalent among women and older age groups. A total of 6.3% reported 'severe chronic pain', and this was more common in older age groups. On multiple logistic regression modelling, female gender, housing tenure, employment category and educational attainment were found to be independently associated with both 'significant' and 'severe' chronic pain. The presence of 'any', 'significant' and 'severe' chronic pain had progressively more marked adverse associations with employment, interference with daily activities and all measured dimensions of general health. CONCLUSIONS: Comparison of the epidemiology of 'significant chronic pain' and 'severe chronic pain' with 'any chronic pain' allows an understanding of the more clinically important end of the chronic pain spectrum. These results support the suggestion that chronic pain is multidimensional, both in its aetiology and in its effects, particularly at this end of the spectrum. This must be addressed in management and in further research.

Activities of Daily Living↗
PubMed2001

Activation of arrestin: requirement of phosphorylation as the negative charge on residues in synthetic peptides from the carboxyl-terminal region of rhodopsin.

PURPOSE: To determine whether substitution of the potential phosphorylation sites of bovine rhodopsin's carboxyl-terminal region with the acidic residues aspartic acid, glutamic acid, or cysteic acid promotes the activation of arrestin. METHODS: Three peptide analogues of the 19-residue carboxyl-terminal region of rhodopsin (330-348) were synthesized: the fully phosphorylated peptide (7P-peptide), the peptide with all potential phosphorylation sites substituted with glutamic acid (7E-peptide), and the peptide with the phosphorylation sites substituted with cysteic acid (7Cya-peptide). The peptides were tested in assays in which the 7P-peptide had previously been shown to have an effect. Rhodopsin with glutamic acid (Etail) or aspartic acid (Dtail) substituted for the phosphorylation sites in rhodopsin were constructed and expressed in COS-7 cells and tested in an in vitro assay. RESULTS: Earlier work has demonstrated that the 7P-peptide activates arrestin, showing induction of arrestin binding to light-activated unphosphorylated rhodopsin, inhibition of the light-induced phosphodiesterase (PDE) activity in rod outer segments (ROS) with excess arrestin, increase in the initial rapid proteolysis of arrestin by trypsin, and enhanced reactivity of one of arrestin's sulfhydryl groups with inhibition of the reactivity of another. None of these effects was observed in the presence of 7E-peptide or 7Cya-peptide. The 7Cya-peptide inhibited the PDE activity in ROS, but the same effect was observed both in the presence and the absence of excess arrestin. Because none of the other effects was observed with the 7Cya-peptide, the authors conclude that the 7Cya-peptide does not activate arrestin, but acts, probably nonspecifically, through some other part of the transduction system. Considerable arrestin-mediated rhodopsin inactivation was observed with both the Etail and the Dtail mutant, although these substitutions did not yield rhodopsins that were equivalent to phosphorylated rhodopsin. CONCLUSIONS: These results, taken together, suggest that the negative charge due to phosphates in the carboxyl-terminal region of rhodopsin are required for the full activation of arrestin and that acidic amino acids (carboxyl and sulfonic) do not mimic the negative charge of phosphorylated residues.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2000

FGF signaling restricts the primary blood islands to ventral mesoderm.

According to the three-signal model of mesoderm patterning in Xenopus, all mesoderm, with the exception of the Spemann organizer, is originally specified as ventral type, such as lateral plate and primary blood islands. It is proposed that the blood islands become restricted to the ventralmost mesoderm because they are not exposed to the BMP-inhibiting activity of the Spemann organizer. We present evidence here that, contrary to predictions of this model, the blood islands remain ventrally restricted even in the absence of Spemann organizer signaling. We further observed that inhibition of FGF signaling with a dominant negative receptor resulted in the expansion of the blood island-forming territory with a concomitant loss of somite. The requirement for FGF signaling in specifying somite versus blood island territories was observed as early as midgastrulation. The nonoverlapping expression domains of Xnr-2 and Xbra in the gastrula marginal zone appear to mark presumptive blood island and somite, respectively. Inhibition of FGF signaling with dominant negative receptor leads to an expansion of Xnr-2 expression and to a corresponding reduction in Xbra expression. On the other hand, we found no evidence that manipulation of BMP signaling, either positively or negatively, altered the expression domains of Xnr-2 and Xbra. These results suggest that FGF signaling, rather than BMP-inhibiting activity, is essential for restriction of the ventral blood islands to ventral mesoderm.

Animals↗
PubMed2000

Primary structure requirements for Xenopus nodal-related 3 and a comparison with regions required by Xenopus nodal-related 2.

Transforming growth factor-beta superfamily members play important roles in the early development of animals. Activin and the Xenopus nodal related proteins 1, 2, and 4 induce muscle actin from Xenopus ectodermal explants, whereas the bone morphogenetic proteins 4 and 7 induce ectoderm to differentiate as epidermis. Bone morphogenetic proteins are antagonized by soluble binding proteins such as noggin and chordin, which leads to expression of neural cell adhesion molecule in animal caps. The transforming growth factor-beta superfamily member Xenopus nodal-related 3 also induces the neural cell adhesion molecule through inhibition of bone morphogenetic proteins. Therefore, whereas Xenopus nodal-related 2 and 3 share a high amount of sequence homology, they lead to very different cell fates. This study investigates the functional domains that distinguish the activities of these two factors. It was found that mutually exclusive regions of nodal-related 2 and 3 were required for activity. The central region of the mature domain is required for nodal-related 2 to induce muscle actin, whereas the N- and C-terminal ends of the mature domain are required for nodal-related 3 to induce neural cell adhesion molecule. These results help to define the minimal domains required for the unique activities of these factors.

Actins↗
PubMed2000

Validation of immunoassays for bioanalysis: a pharmaceutical industry perspective.

Immunoassays are bioanalytical methods in which quantitation of the analyte depends on the reaction of an antigen (analyte) and an antibody. Although applicable to the analysis of both low molecular weight xenobiotic and macromolecular drugs, these procedures currently find most consistent application in the pharmaceutical industry to the quantitation of protein molecules. Immunoassays are also frequently applied in such important areas as the quantitation of biomarker molecules which indicate disease progression or regression, and antibodies elicited in response to treatment with macromolecular therapeutic drug candidates. Currently available guidance documents dealing with the validation of bioanalytical methods address immunoassays in only a limited way. This review highlights some of the differences between immunoassays and chromatographic assays, and presents some recommendations for specific aspects of immunoassay validation. Immunoassay calibration curves are inherently nonlinear, and require nonlinear curve fitting algorithms for best description of experimental data. Demonstration of specificity of the immunoassay for the analyte of interest is critical because most immunoassays are not preceded by extraction of the analyte from the matrix of interest. Since the core of the assay is an antigen-antibody reaction, immunoassays may be less precise than chromatographic assays; thus, criteria for accuracy (mean bias) and precision, both in pre-study validation experiments and in the analysis of in-study quality control samples, should be more lenient than for chromatographic assays. Application of the SFSTP (Societe Francaise Sciences et Techniques Pharmaceutiques) confidence interval approach for evaluating the total error (including both accuracy and precision) of results from validation samples is recommended in considering the acceptance/rejection of an immunoassay procedure resulting from validation experiments. These recommendations for immunoassay validation are presented in the hope that their consideration may result in the production of consistently higher quality data from the application of these methods.

Algorithms↗
PubMed2000

Not to be and then to be: visual representation of ignored unfamiliar faces.

Negative priming, the increase in response time and/or errors to targets previously encountered as distractors, is explained by inhibitory mechanisms that block the access of distractor representations to response systems. The processing of unfamiliar human faces was investigated using negative priming. Observers viewed a row of faces to decide whether 2 target faces were the same or different. Response latencies were longer when 1 or both targets had appeared as distractors on the immediately preceding trial--evidence that never-before seen faces are represented and require inhibition. Response latencies were shorter when face targets had appeared as distractors, either corrupted with high-frequency noise or contrast inverted--evidence that representations are facilitated. Finally, response latencies remained unaltered when face targets had appeared as upside-down distractors--evidence that not all distractor representations afford response priming. The visual system indeed represents ignored unfamiliar faces, but blocks these representations only if they vie with targets for the control of action.

Adult↗
PubMed2000

Chemoprophylaxis is effective in the prevention of leprosy in endemic countries: a systematic review and meta-analysis. MILEP2 Study Group. Mucosal Immunology of Leprosy.

OBJECTIVE: To quantify the efficacy of chemoprophylaxis against leprosy. METHOD: Literature searching of Medline and Embase databases, hand-searching of references and correspondence with investigators. STUDY SELECTION: published papers relating to the prevention of leprosy and the use of chemotherapy in leprosy were identified for critical appraisal. Trials were selected and grouped into three categories according to study design and control groups. DATA ANALYSIS: the relative risks (RR) with 95% confidence intervals were calculated from the original data using a random effects model. To assess the cost-effectiveness of chemoprophylaxis, a further analysis of the rates of disease in the trial and control groups was done based on the numbers needed to be treated (NNT) to prevent one new case of leprosy. RESULTS: A total of 14 trials were identified from 127 published papers on chemoprophylaxis of leprosy. The trials were categorized into randomized controlled trials, non-randomized controlled trials, and uncontrolled trials. The overall results of the meta-analysis shows that chemoprophylaxis gives around 60% protection against leprosy. The NNT are low in trials of household contacts. CONCLUSIONS: The evidence shows that chemoprophylaxis against leprosy is an effective way to reduce the incidence of leprosy, particularly in household contacts. The role of chemoprophylaxis needs to be re-examined using newer drugs given the continuing case detection rates globally.

Acedapsone↗