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Biomedical subjects

R E Thomas

Publications and source records attributed to R E Thomas.

At least 55 records · Page 3Linked to original sources
PubMed1993

Effects of exercise on carpal tunnel syndrome symptoms.

This is a study of whether participation in an exercise programme for increasing upper extremity flexibility, strength, and circulation has any effects on symptoms of carpal tunnel syndrome (CTS). Two groups (exercise and control) of seven participants each who did repetitive hand motion tasks were studied. The exercise group participated in daily arm, hand, and other upper-extremity exercises for 8 weeks. The control group did not participate in the exercise programme. Dependent (response) variables monitored were motor nerve conduction latency through the carpal tunnel, grip strength, and subjective comfort in the dominant hands of participants. Test results indicated no statistically significant differences in nerve conduction latency or subjective comfort between the two groups. Significant differences did develop in grip strengths over time, suggesting that the exercise group may have benefited physiologically from the exercise programme.

Journal Article↗
PubMed1993

The effects of biofeedback on carpal tunnel syndrome.

Behaviour modification based on audible electromyographic (EMG) biofeedback signals was used to discourage the awkward hand postures and the exertion of excessive force with the fingers, which are suspected of causing carpal tunnel syndrome (CTS). The null hypothesis was that participation in such a biofeedback programme has no effect on CTS symptoms. Before and during an 8-week study, data were collected from two groups of five female assembly line workers each. The biofeedback group received training and input, while the control group did not. Test results indicated that the null hypothesis could not be rejected.

Adult↗
PubMed1993

Effect of Yersinia pestis infection on temperature preference and movement of the Oriental rat flea (Xenopsylla cheopis) (Siphonaptera: Pulicidae).

Previous laboratory studies have shown that inoculation of bacterial endotoxin into the hemocoel of some arthropods, or natural infection by a number of pathogens, causes them to seek out a higher ambient temperature. This phenomenon has been called behavioral fever. Yersinia pestis is an endotoxin-producing bacterium that relies on infection of fleas for transmission. Behavioral fever in fleas might enhance the transmission of plague if infected fleas were induced to seek out a warm-bodied host after the death of an infected host. Our study indicates that in thermal gradient Y. pestis infected Oriental rat fleas (Xenopsylla cheopis) do not exhibit behavioral fever and in one experiment sought out a significantly lower temperature.

Animals↗
PubMed1993

Fleas (Siphonaptera) infesting giant kangaroo rats (Dipodomys ingens) on the Elkhorn and Carrizo Plains, San Luis Obispo County, California.

The giant kangaroo rat, Dipodomys ingens (Merriam), has a limited distribution in the San Joaquin Valley, CA. Because of reductions in its geographic range, largely resulting from humans, the species was listed as an endangered species in 1980 by the California Fish and Game Commission. As part of a study of the community ecology of southern California endangered species, including D. ingens, we were able to make flea collections from the rats when they were trapped and marked for population studies. All but one of the fleas collected from the D. ingens in this study were Hoplopsyllus anomalus, a flea normally associated with ground squirrels (Sciuridae). It has been suggested that giant kangaroo rats fill the ground squirrel niche within their range. Our data indicate that this role includes a normal association with Hoplopsyllus anomalus.

Animals↗
PubMed1993

Midgut basal lamina thickness and dengue-1 virus dissemination rates in laboratory strains of Aedes albopictus (Diptera: Culicidae).

Strain differences in midgut basal lamina thickness, assessed by measurement in transmission electron micrographs, and disseminated infection rates of dengue-1 virus were compared among three laboratory strains of Aedes albopictus (Skuse). Mean basal lamina thickness for the New Orleans and Houston strains were significantly greater than those for the Oahu strain, which exhibits a higher disseminated infection rate than the former two. Although basal lamina thickness among the F1 progeny of reciprocal crosses of the Oahu and Houston strains were intermediate between the parental strains, they were too variable to be useful as markers in genetic studies. Measurements of basal laminae among individuals of the New Orleans strain, with disseminated or nondisseminated infections, failed to demonstrate a role for basal lamina thickness as a modulator of dengue-1 virus dissemination across the midgut epithelium of Ae. albopictus.

Aedes↗
PubMed1993

Methods of teaching medicine using cases.

One form of experiential learning is the case study. It may have many formats: the structured bedside case; patient management problems; extended case studies; clinico-pathological conferences; computerized or video-disc case studies; and classroom electronic display of student responses. There are few randomized controlled trials comparing teaching by the case method with lectures, and none of the educational trials have adequate power. Researchers need to include biostatisticians and psychometricians in their research teams if the case method of teaching in medicine is to be adequately tested.

Education, Medical↗
PubMed1992

Variation in the efficiency of vertical transmission of dengue-1 virus by strains of Aedes albopictus (Diptera: Culicidae).

Five geographical strains of Aedes albopictus (Skuse) were compared for their ability to transmit vertically a dengue-1 isolate from Jamaica. The OAHU strain of Ae. albopictus and a strain of Aedes aegypti (L.) from the United States were included as controls. The offspring of orally infected females were assayed individually for vertical infection. Vertical transmission rates among strains ranged from 11 to 41%, and filial infection rates of strains ranged from 0.5 to 2.9%. Filial infection rates of individual positive families within strains ranged from 1.4 to 17.4%. These rates were higher than those previously recorded for Ae. albopictus. The observed differences in rates of vertical transmission among the strains were not statistically significant, because 95% of the measured variation was attributed to families within strains. The most significant source of variation in vertical transmission of dengue-1 by Ae. albopictus was at the individual level.

Aedes↗
PubMed1992

Teaching medicine with cases: student and teacher opinion.

In a second-year family medicine course taught using simulated patients the students commented most favourably on the clinical relevance of the topics, the enthusiasm of teachers, and the opportunity to interview simulated patients with their fellow students, in contrast to their basic science courses, which did not give them patient contact. They felt most confident about skills acquired in relation to diseases with a limited number of key symptoms, signs and treatments (meningitis, otitis) and less confident about diseases with many symptoms and treatments (diabetes, trauma, arrhythmias). They made few comments about alternative cases which might have been selected. Their adverse comments were about the workload. During tutor meetings over 4 years, a key concern which emerged was to find cases with a level of complexity suitable to the students. The tutors emphasized these principles of case selection: the cases should be based on real life and include most of the signs and symptoms of the disease; contain one or at most two foci; have nodal decision-making points; emphasize clinical reasoning; reinforce prior knowledge; permit the transfer of knowledge to other cases; and permit the assessment of associated technical skills.

Attitude of Health Personnel↗
PubMed1992

Failure of intragastrically administered Yersinia pestis capsular antigen to protect mice against challenge with virulent plague: suppression of fraction 1-specific antibody response.

We evaluated the Yersinia pestis capsular (fraction 1 [F1]) antigen as a potential oral immunogen in mice. We found that single doses of as much as 0.4 mg of F1, administered by intragastric (ig) intubation, were unprotective and did not stimulate production of detectable levels of specific antibody. Three weekly ig doses resulted in low serum antibody levels that also did not provide protection against challenge with virulent Y. pestis. Assays of type-specific antibody following intubation and subsequent challenge with a subcutaneous inoculation of F1 revealed that the quantity of antigen intubated and the secondary IgG2a antibody levels were inversely related, suggesting the induction of tolerance to intragastrically administered F1 antigen. Transfer of spleen cells from intubated mice to F1 immune recipients failed to demonstrate suppression of specific antibody, indicating that the immune tolerance observed in intubated mice was not due to a T suppressor cell-mediated effect. The results of this study indicate that Y. pestis F1 antigen is not likely to be an efficacious immunogen for oral vaccination of mice against plague.

Animals↗
PubMed1992

Cystitis induced by infection with the Lyme disease spirochete, Borrelia burgdorferi, in mice.

Previous studies have demonstrated that the urinary bladder is a consistent source for isolating the Lyme disease spirochete, Borrelia burgdorferi, from both experimentally infected and naturally exposed rodents. We examined histopathologic changes in the urinary bladder of different types of rodents experimentally infected with Lyme spirochetes, including BALB/c mice (Mus musculus), nude mice (M. musculus), white-footed mice (Peromyscus leucopus), and grasshopper mice (Onychomys leucogaster). Animals were inoculated intraperitoneally, subcutaneously, or intranasally with low-passaged spirochetes, high-passaged spirochetes, or phosphate-buffered saline. At various times after inoculation, animals were killed and approximately one-half of each urinary bladder and kidney were cultured separately in BSK-II medium while the other half of each organ was prepared for histologic examination. Spirochetes were cultured from the urinary bladder of all 35 mice inoculated with low-passaged spirochetes while we were unable to isolate spirochetes from any kidneys of the same mice. The pathologic changes observed most frequently in the urinary bladder of the infected mice were the presence of lymphoid aggregates, vascular changes, including an increase in the number of vessels and thickening of the vessel walls, and perivascular infiltrates. Our results demonstrate that nearly all individuals (93%) of the four types of mice examined had a cystitis associated with spirochetal infection.

Animals↗
PubMed1990

Experimental infection of Ornithodoros spp. ticks (Acari: Argasidae) with Yersinia pestis.

Ticks of the genus Ornithodors feed on many rodent species with known roles in maintaining and amplifying plague (Yersinia pestis) in nature. Five species of ticks in this genus are shown to acquire the plague bacillus by feeding on infected hosts. Most notably, 80% of O. hermsi Wheeler, Herms and Meyer harbored Y. pestis 1 mo after an infectious blood meal. Subsequent transmission by infected ticks was not demonstrated. However, 1 yr after the infectious feeding, Y. pestis DNA was detected using a hybridization probe on tick triturates that were amplified by in vitro cultivation. Y. pestis can remain reproductively viable for at least 1 yr in about 2% of ticks fed on infected hosts.

Animals↗
PubMed1990

Recombinant capsular antigen (fraction 1) from Yersinia pestis induces a protective antibody response in BALB/c mice.

Yersinia pestis produces a glycoprotein capsule, the biosynthesis of which appears to be temperature dependent. The fraction I (F1) component of this capsule is specific to Y. pestis and the detection of F1 antibodies is the basis for several serological tests. We report the cloning of the F1 gene and its expression in Escherichia coli using the phagemid vector lambda ZAPII and a F1-specific monoclonal antibody. The recombinant F1 antigen had a molecular weight of 17 kDa, which proved to be identical to that of the F1 antigen produced by Y. pestis. The recombinant cells produced F1 antigen at 37 degrees C but only minimal amounts at 27 degrees C, suggesting that the genetic features affected by temperature in Y. pestis may be operating in the E. coli clone. It is not known if their similar molecular weights reflect the glycosylated nature of both proteins. F1 antigen purified from the E. coli recombinant induced a protective immune response in BALB/c mice challenged with up to 10(5) virulent Y. pestis. The resistance of immunized mice to plague infection correlated with high titers of F1 antibody. The cloned gene expresses an immunogenically competent F1 antigen suitable for use in plague serodiagnostics and vaccine development.

Animals↗
PubMed1989

Use of DNA hybridizations probes for detection of the plague bacillus (Yersinia pestis) in fleas (Siphonaptera: Pulicidae and Ceratophyllidae).

The detection of active plaque in nature relies primarily on demonstration of the etiologic agent of the disease. Yersinia pestis, in the flea vectors and susceptible mammalian hosts. A live animal assay is currently used for identification of a Y. pestis virulence antigen that is not expressed in the flea. We have found that DNA hybridization probes specific for Y. pestis, used in very simple sample preparation schemes, allow detection of Y. pestis in three species of fleas as well as tissues of experimentally infected mice at minimum concentrations of 1 x 10(6) bacilli/ml. We detected Y. pestis in 22 of 90 (24%) experimentally infected Xenopsylla cheopis (Rothschild), 13 of 25 (52%) Thrassis bacchi (Rothschild), and 9 of 25 (36%) Diamanus montanus (Baker), but no hybridization signals were observed from fleas that had fed on normal mice. The probe technique indicated infection in 9 of 10 potentially infected liver and spleen samples and none of the 5 control samples. Our techniques permit definitive diagnosis in 48 h.

Animals↗
PubMed1989

Experimentally induced plague infection in the northern grasshopper mouse (Onychomys leucogaster) acquired by consumption of infected prey.

In this study, 20 laboratory reared Onychomys leucogaster from a parental population that is naturally exposed to plague were each fed a white mouse that had been inoculated with Yersinia pestis. Three of the 20 O. leucogaster died, four survived with antibody titers against Y. pestis and 13 survived with no titer against Y. pestis. In contrast, when 20 O. leucogaster from a plague naive parental population were fed infected prey, seven died and 13 survived with no antibody titer against Y. pestis. Our results suggest another means by which O. leucogaster from populations that are naturally exposed to plague may acquire the disease.

Animals↗
PubMed1988

Identification of a Yersinia pestis-specific DNA probe with potential for use in plague surveillance.

A 900-base-pair DNA fragment derived from a 9.5-kilobase plasmid in Yersinia pestis hybridized specifically with Y. pestis DNA. We demonstrated the feasibility of using this DNA fragment to detect plague bacilli directly in fleas, suggesting that this Y. pestis-specific DNA probe may be used for plague surveillance in the field. Additional applications for this DNA probe may include plague diagnosis and pathogenesis research.

Animals↗
PubMed1988

Susceptibility to Yersinia pestis in the northern grasshopper mouse (Onychomys leucogaster).

The laboratory-born progeny from two geographically distant populations of northern grasshopper mice (Onychomys leucogaster) were challenged with Yersinia pestis to determine their relative susceptibilities to plague. One of the O. leucogaster populations was associated with a known epizootic focus of the disease and was found to be nearly 2,000 times more resistant to mortality than were members of another population from an area historically free of plague. The ecology and omnivorous behavior of O. leucogaster appears to promote strong selection for resistance to plague in areas where they are naturally exposed.

Animals↗