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Biomedical subjects

R J Thomas

Publications and source records attributed to R J Thomas.

At least 19 recordsLinked to original sources
PubMed1995

The risk of human T cell leukemia virus and viral hepatitis infection among US Marines stationed in Okinawa, Japan.

The prevalence and incidence of human T cell leukemia virus type I/II (HTLV-I/II) and hepatitis A, B, and C virus infection were determined among US Marines stationed in Okinawa, Japan. Of 2875 personnel, 2 (0.07%) had antibody to HTLV-I/II. After 1-3 years, no HTLV seroconversions were observed, although 23% reported sexual contact with Okinawans. Of 1010 hepatitis-tested marines, 121 (12%) had antibody to hepatitis A virus (anti-HAV), 26 (2.6%) had antibody to hepatitis B core antigen (anti-HBc), and 2 (0.2%) had antibody to hepatitis C virus (anti-HCV). On follow-up, 1 subject seroconverted to anti-HAV, 8 to anti-HBc, and none to anti-HCV. Most marines with recent hepatitis B infection were young, single, and enlisted and had been on short deployments to other countries in Southeast Asia. Marines stationed in Okinawa are not at high risk for HTLV infection but are at increased risk for hepatitis B infection and should be considered for vaccination.

Adolescent↗
PubMed1995

Excitatory amino acids in health and disease.

PURPOSE: To review the role of excitatory neurotransmitters in normal mammalian brain function, the concept of excitotoxic neuronal death as an important final common path in a variety of diseases, and modification of excitatory synaptic transmission as an important new pharmacological principle. These principles are discussed, with special emphasis on diseases of importance to older adults. DATA SOURCES: A MEDLINE search from 1966 to May 1995 was undertaken, as well as a manual search of current issues of clinical and basic neuroscience journals, for articles that addressed glutamate N-methyl-D-aspartate and/or excitotoxicity. STUDY SELECTION: A total of 5398 original and 68 review articles were identified that addressed animal and human experimentation relevant to excitotoxic neuronal death. There were 364 articles with potential significance for clinical application identified; 132 of the most recent references are provided. DATA EXTRACTION: All articles were classified into three categories: general receptor, biology pathogenesis of disease, and pharmacotherapy. RESULTS: Glutamic and aspartic acids are the physiological mediators of most excitatory synaptic transmission. This is critical to several normal nervous system functions, including memory and long-term modification of synaptic transmission and nociception. Activation of the inotropic NMDA and non-NMDA receptors increases transmembrane calcium and sodium fluxes, and the metabotropic glutamate receptor activation results in generation of inositol triphosphate and inhibition of adenylate cyclase. Numerous modulatory sites exist, especially on the NMDA receptor. Nitric oxide, arachidonic acid, superoxide, and intracellular calcium overload are the ultimate mediators of neuronal death. Glutamate re-uptake transporters belong to a unique family of amino acid transport systems, the malfunction of which is intricately involved in disease pathogenesis. Ischemic stroke, hypoglycemia, Parkinson's disease, alcohol intoxication and withdrawal, Alzheimer's disease, epilepsy, and chronic pain syndromes are only some of the important clinical neurological disorders with a major pathogenic role for the excitatory amino acids. CONCLUSIONS: Pharmacological manipulation of the excitatory amino acid receptors is likely to be of benefit in important and common diseases of the nervous system. Only a few of the currently available drugs that modify excitatory neurotransmission, such as remacemide, lamotrigine, and tizanidine, have an acceptable therapeutic index. The identification of numerous receptor subtypes, topographic variabilities of distribution, and multiple modulatory sites will provide a true challenge to the neuropharmacologist.

Aged↗
PubMed1995

Acceptance of screening for colorectal cancer by flexible sigmoidoscopy.

OBJECTIVE: To determine the acceptance rate of screening by flexible sigmoidoscopy in a sample of general practice patients aged 50 to 60, and the acceptability of the procedure among those undergoing the test. SETTING: Recruitment took place in selected general practices in Melbourne, Australia. Flexible sigmoidoscopies were performed at the local public hospital. PATIENTS AND METHODS: 187 patients aged between 50 and 60, and without bowel symptoms, were seen by one of 12 non-randomly selected general practitioners during the study period. At the conclusion of routine consultation general practitioners discussed colorectal screening with eligible patients and recommended that they attend a free screening clinic at the local hospital. The patients who attended the clinic underwent flexible sigmoidoscopy performed by experienced endoscopists. Clinic attenders completed a questionnaire which measured perceptions of the screening visit. RESULTS: The attendance rate was 49%. All clinic attenders were satisfied with the care received at clinic. Sixty five per cent of people experienced either no discomfort or mild discomfort, while 15% of people experienced moderate or severe pain. A bloated feeling was common (80%), with around 36% of people experiencing moderate or extreme bloating. Most people said that they were not at all embarrassed (64%), though 9% reported moderate or extreme embarrassment. Seventeen people (19%) were found to have polyps. CONCLUSIONS: Although the procedure was acceptable to those who underwent the screening test, further research on effective recruitment strategies is required if a full scale flexible sigmoidoscopy screening programme is to be considered feasible.

Age Factors↗
PubMed1995

Glutamine transaminase K is not a major cysteine S-conjugate beta-lyase of rat kidney mitochondria: evidence that a high-molecular weight enzyme fulfills this role.

Glutamine transaminase K (homodimer; M(r) of monomer approximately 45,000) is a major cysteine S-conjugate beta-lyase of rat kidney cytosol. Several cysteine S-conjugates are known to cause kidney damage. Mitochondria are especially sensitive, and glutamine transaminase K activity is present in the mitochondrial fraction of rat kidneys. Therefore, it is possible that the mitochondrial form of glutamine transaminase K is a cysteine S-conjugate beta-lyase of the rat kidney and that this activity contributes to the mitochondrial damage. However, the literature contains conflicting data on this point. We obtained highly purified mitochondrial glutamine transaminase K and showed that it possesses little cysteine S-conjugate beta-lysae activity with S-(1,2-dichlorovinyl)-L-cysteine and S-(1,1,2,2-tetrafluoroethyl)-L-cysteine as substrates. Recently, a high-molecular-weight cysteine S-conjugate beta-lyase (M(r) approximately 330,000) was shown to be present in the cytosol of rat kidney homogenates and partially purified. We present evidence that suggests that a similar high-molecular-weight enzyme is present in rat kidney mitochondria and that this protein may be a major cysteine S-conjugate beta-lyase of these organelles.

Animals↗
PubMed1994

A case-management system for coronary risk factor modification after acute myocardial infarction.

OBJECTIVE: To evaluate the efficacy of a physician-directed, nurse-managed, home-based case-management system for coronary risk factor modification. DESIGN: Randomized clinical trial in which patients received a special intervention (n = 293) or usual medical care (n = 292) during the first year after acute myocardial infarction. SETTING: 5 Kaiser Permanente Medical Centers in the San Francisco Bay area. PATIENTS: 585 men and women aged 70 years or younger who were hospitalized for acute myocardial infarction. INTERVENTION: In the hospital, specially trained nurses initiated interventions for smoking cessation, exercise training, and diet-drug therapy for hyperlipidemia. Intervention after discharge was implemented primarily by telephone and mail contact with patients in their homes. All medically eligible patients received exercise training; all smokers received the smoking cessation intervention; and all patients received dietary counseling and, if needed, lipid-lowering drug therapy. OUTCOME: Smoking prevalence and plasma low-density lipoprotein cholesterol (LDL) concentrations were measured 2 months after infarction, and functional capacity was measured 6 months after infarction. RESULTS: In the special intervention and usual care groups, the cotinine-confirmed smoking cessation rates were 70% and 53% (P = 0.03), plasma LDL cholesterol levels were 2.77 +/- 0.69 mmol/L and 3.41 +/- 0.90 mmol/L (107 +/- 30 mg/dL and 132 +/- 30 mg/dL) (P = 0.001), and functional capacities were 9.3 +/- 2.4 METS and 8.4 +/- 2.5 METS (P = 0.001), respectively. CONCLUSION: In a large health maintenance organization, a case-management system was considerably more effective than usual medical care for modification of coronary risk factors after myocardial infarction.

Adult↗
PubMed1994

Neurotoxicity of antibacterial therapy.

The increasing variety of drugs available for the treatment of bacterial infections has simultaneously increased the potential for toxicity. Neurologic toxicity of antibacterial therapy is generally underestimated in scope and severity; it may be classified as central, peripheral, or due to drug-interactions, several of which are potentially life-threatening. beta-Lactams and the quinolones are the drugs most commonly associated with seizures and encephalopathy. Drug-induced ototoxicity is common, and sensitive tests are now available for early diagnosis of both cochlear and vestibular toxicity. Testing in clinical practice is best restricted to subgroups at high risk. The aminoglycosides, tetracyclines, clindamycin, erythromycin, polymyxins, and possibly ampicillin have the potential to aggravate neuromuscular disease. Ethambutol, isoniazid, and chloramphenicol are toxic to the optic nerve; bismuth can cause a myoclonic encephalopathy. A number of less common and/or unusual toxicities are also discussed.

Adult↗
PubMed1994

Blinking and the release reflexes: are they clinically useful?

OBJECTIVE: To review the clinical utility of blinking and the release reflexes, palmomental, glabellar, grasp, and snout, as an important part of the bedside neurological examination. DESIGN: Articles published from 1966 to 1993 that addressed blinking or the release reflexes were identified by searching the MEDLINE database. Thirty-seven references provided clinically useful and applicable information. RESULTS: There is controversy regarding the optimal method of clinical elicitation of these reflexes. The release reflexes are frequently seen as an incidental abnormality in the elderly. A positive grasp reflex, especially if asymmetrical, is sensitive but not specific for abnormal brain function. Lack of habituation is more important than the mere presence or absence of a reflex. The brainstem circuits involved in the regulation of blinking and the release reflexes are discussed, as are their abnormalities in a variety of clinical settings. CONCLUSION: Blinking and the release reflexes have clinical utility in the diagnosis and bedside clinical assessment of diseases as diverse as frontal lobe lesions, hydrocephalus, multiple sclerosis, Parkinson's disease, Alzheimer's disease and other dementias, falls in the elderly, ageing, HIV-encephalopathy, schizophrenia, tumors in the region of the sylvian aqueduct and recovery from head trauma.

Blinking↗
PubMed1994

Application of PCR to a clinical and environmental investigation of a case of equine botulism.

PCR for the detection of botulinum neurotoxin gene types A to E was used in the investigation of a case of equine botulism. Samples from a foal diagnosed with toxicoinfectious botulism in 1985 were reanalyzed by PCR and the mouse bioassay in conjunction with an environmental survey. Neurotoxin B was detected by mouse bioassay in culture enrichments of serum, spleen, feces, and intestinal contents. PCR results compared well with mouse bioassay results, detecting type B neurotoxin genes in these samples and also in a liver sample. Other neurotoxin types were not detected by either test. Clostridium botulinum type B was shown to be prevalent in soils collected from the area in which the foal was raised. Four methods were used to test for the presence of botulinum neurotoxin-producing organisms in 66 soil samples taken within a 5-km radius: PCR and agarose gel electrophoresis (types A to E), PCR and an enzyme-linked assay (type B), hybridization of crude alkaline cell lysates with a type B-specific probe, and the mouse bioassay (all types). Fewer soil samples were positive for C. botulinum type B by the mouse bioassay (15%) than by any of the DNA-based detection systems. Hybridization of a type B-specific probe to DNA dot blots (26% of the samples were positive) and PCR-enzyme-linked assay (77% of the samples were positive) were used for the rapid analysis of large numbers of samples, with sensitivity limits of 3 x 10(6) and 3,000 cells, respectively. Conventional detection of PCR products by gel electrophoresis was the most sensitive method (300-cell limit), and in the present environmental survey, neurotoxin B genes only were detected in 94% of the samples.

Animals↗
PubMed1993

Lead exposures during shipboard chipping and grinding paint-removal operations.

Shipboard chipping and grinding paint-removal operations were evaluated to determine personnel exposures to airborne lead concentrations. Lead concentrations found in the bulk lead-paint samples ranged from 0.0037 to 11.5% by weight. Of the personnel conducting paint removal operations, 62% were exposed at or above the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit for lead of 50 micrograms/m3. Correlations of airborne lead concentrations and bulk lead-paint contents for chipping and grinding operations were statistically significant. Blood lead (Pb) levels were significantly higher in the follow-up blood tests when compared to the initial blood tests taken prior to paint removal. However, blood Pb levels were well below the OSHA allowable level of 40 micrograms/100 g.

Air Pollutants, Occupational↗
PubMed1992

Return to work after uncomplicated myocardial infarction: a trial of practice guidelines in the community.

OBJECTIVE: To evaluate the effectiveness of practice guidelines for return to work after acute myocardial infarction when disseminated from a university-based setting to a practice-based setting. DESIGN: Randomized clinical trial. PATIENTS: A total of 187 patients with uncomplicated acute myocardial infarction. INTERVENTION: Patients were randomly assigned to the intervention (n = 95) or to usual care (n = 92). The intervention consisted of a treadmill test, a counseling session based on the test results, and a consultation letter from a cardiologist to the primary care physician. Individualized recommendations for the timing of return to work, contained in the consultation letter, were based on the patient's risk for recurrent cardiac events. MEASUREMENTS: Questionnaire, chart review, and a phone interview documented the timing of return to work and the rates of cardiac death, coronary angioplasty, coronary artery surgery, and recurrent myocardial infarction. RESULTS: Median intervals between acute myocardial infarction and return to work were similar in both groups (intervention, 54 days; usual care, 67 days; P greater than 0.2). Among patients without myocardial ischemia, however, the interval was shorter in the intervention group than in the usual care group (38 days compared with 65 days, respectively, P = 0.008). Among patients with myocardial ischemia, intervals were similar in both groups (80 days compared with 76 days, respectively, P greater than 0.2). CONCLUSION: Practice guidelines developed in a university-based setting were not as successful in hastening return to work after uncomplicated acute myocardial infarction when tested in a practice-based setting. Physicians' reluctance to follow guidelines for patients with myocardial ischemia reflected their concern with prognosis even though medical outcome was good.

Adult↗
PubMed1992

Suspected botulism in three intensively managed Australian cattle herds.

Serious outbreaks of a paralytic disease in cattle occurring in the spring and summer of 1988 were investigated on three farms in south eastern Queensland, Australia. On one farm 237 (31 per cent) of 770 cattle died, on the second 109 (40 per cent) of 271 cattle died and on the third 30 (8 per cent) of 380 cows died. Botulism was suspected on the basis of the clinical signs, the lack of significant pathology, a failure to incriminate other agents and a positive feeding trial in one sheep. Laboratory tests for the presence of botulinum toxin failed to confirm this diagnosis, and further feeding trials using ingredients of two rations were also negative.

Animal Feed↗
PubMed1992

The efficacy of an albendazole intraruminal controlled-release device against gastrointestinal parasitism in lambs.

The effectiveness of albendazole in a controlled-release bolus in controlling gastrointestinal nematodes in lambs was assessed during the summer of 1986. Faecal egg counts were almost entirely negative throughout in the treated group and larval challenge remained low at below 2000 larvae kg-1. Untreated control lambs showed a characteristic pattern of auto-infection, culminating in a peak pasture larval count of over 70,000 larvae kg-1 and an outbreak of parasitic gastroenteritis in September associated with a serum pepsinogen concentration of 1.183 IU tyrosine and a mean worm burden of 91,165 nematodes at necropsy, including Ostertagia, Trichostrongylus and Nematodirus species. Subject to the restrictions imposed by the size of the bolus, this was considered to be a highly effective method of seasonal parasite control.

Abomasum↗
PubMed1992

Adult onset Still's disease: clinical experience with 18 patients over 15 years in northern India.

Over a 15 year period 18 patients (eight men, 10 women), 16-50 years old, were diagnosed as having adult onset Still's disease. Fever and arthralgia were always present but prominent lymphadenopathy was uncommon and the serosa were rarely affected. The typical rash of this disease was observed in nine patients. Several complications, including deforming arthritis, amyloidosis, granulomatous hepatitis, uveitis, scleritis, cutaneous vasculitis, and cardiomyopathy, were observed during follow up. Two patients were affected by a nosocomial infection during immunosuppressive treatment for uncontrolled disease. There were no characteristic features at necropsy. Ten patients had a monocyclic course that responded well to aspirin and indomethacin, whereas eight had a polycyclic pattern which invariably required treatment with corticosteroids. Serious complications developed exclusively in the latter group. This group of patients requires early, intensive disease modifying treatment.

Adolescent↗