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Biomedical subjects

C B Thomas

Publications and source records attributed to C B Thomas.

At least 19 recordsLinked to original sources
PubMed1995

Temporal stability of the virus load of cattle infected with bovine leukemia virus.

The relative virus load of bovine leukemia virus (BLV) infected cattle was measured by an immunoperoxidase infectivity assay (IPIA), and by immunoperoxidase staining of cultured leukocytes using a monoclonal antibody to the capsid protein (p24) of BLV. The results of paired sample data taken at different time points spanning 2-3 years show that BLV-infected cattle are stable regarding the amount of BLV produced by their peripheral blood mononuclear cells (PBMCs). Spearman's Rank Correlation demonstrated significant relationships between data from individual cattle taken at four different time points. In addition, this study documents the large range of variation in the virus load of individual cattle.

Animals↗
PubMed1995

Impact of age and environment on somatic mutation at the hprt gene of T lymphocytes in humans.

Analysis of two human populations for dependence of somatic mutation on age has revealed both similarities and differences. The studies performed employed peripheral blood lymphocytes and measured the efficiency with which these cells form clones in vitro (cloning efficiency, CE) and the frequency of cells with inactivating mutations of the hypoxanthine phosphoribosyltransferase gene (mutant frequency, MF). The people studied were between 19 and 64 years of age. In one population, composed of 78 never smokers and 140 current smokers from the United States (US), both CE and MF were dependent on age: CE declined with age (p = 0.005); MF increased 0.15 per 10(6) cells per year of age for nonsmokers (p < 0.001) and at 1.3 times that rate for smokers (p = 0.01). In the second population, 80 people of unknown smoking status from Russia, the increase in MF per year was even greater, 2.5 times that of the US nonsmokers (p = 0.001) but the dependence of CE on age was the same as for the US population (p = 0.043). Because the increase of MF of the Russians with age is 2-fold greater than that of the US smokers, the intensity of smoking and/or other environmental exposures, or the susceptibility to these exposures, must account for the difference in age dependent MF increase, not the proportion of Russians that are smokers. Differences in the lymphocyte subpopulations that survived the longer transit from Russia may have contributed to the observed differences in MF. However, overall, the mutant frequency results suggest that the Russians were chronically exposed to higher levels of agents that induce somatic mutation and that, on an age adjusted basis, the Russia population studied is at increased risk for health consequences from accumulated genetic damage.

Adult↗
PubMed1994

Experience with symptomatic spinal epidural cysts.

Epidural cysts, either synovial or ganglion, are an unusual cause of epidural compressive syndromes. We report a series of 26 patients with cysts, including 1 cervical, 2 thoracic, and 23 lumbar. Complaints at the time of admission and findings were similar to those associated with other epidural lesions at the same locations. The surgical technique is similar to that for other spinal lesions, with a wide exposure to enable a clear view of the cyst and surrounding structures, and is governed by imaging studies. Patients with cervical and thoracic lumbar cysts were free of symptoms and signs postoperatively. Of the 23 patients with lumbar cysts, 15 were free of symptoms after an operation, 7 had symptomatic improvement but had some pain and neurological findings, and 1 patient had no improvement. Computed tomography and magnetic resonance imaging permit accurate preoperative evaluation.

Adult↗
PubMed1994

Evaluation of an enzyme-linked immunosorbent assay that uses the 41-kd flagellin as the antigen for detection of antibodies to Borrelia burgdorferi in cattle.

An ELISA was developed to detect antibodies to the 41-kd flagellin (P41) of Borrelia burgdorferi in serum obtained from cattle. Absorption studies, immunoblot analysis, immunoelectron microscopy, and correlation of results of the P41-ELISA and the P39-ELISA as well as measurement of the antibody to P41 in calves challenge-exposed with Borrelia theileri were used to assess the specificity of the P41-ELISA. Antigens derived from Escherichia coli, Leptospira interrogans serovar hardjo, and B burgdorferi were used for absorption studies and immunoblot analysis. Antibodies to P41 of B burgdorferi cross-reacted with antigens of E coli, but were not cross-reactive with L hardjo. A value 3 SD higher than the mean of the negative-control population of cattle was defined as the minimum value (cutoff value) for a positive result by the P41-ELISA. Use of this value for classification of test results reduced the predicted rate of false-positive results attributable to E coli cross-reactivity to 1%. Immunoblot analysis revealed that test-positive serum from cattle reacted mainly with 41-, 39-, 34-, and 31-kd proteins of B burgdorferi, as well as several smaller proteins. Immunoelectron microscopy revealed that serum from cattle that was test-positive by the P41-ELISA bound to the flagellin and outer membrane of B burgdorferi. Results of absorption studies, immunoblot analysis, and immunoelectron microscopy were correlated and indicated that serum from cattle that was test-positive by P41-ELISA had stronger reactivity to B burgdorferi antigens than to antigens of E coli or L hardjo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The growth of two murine hemangioendotheliomas intracranially, subcutaneously, and in culture, and their comparison with human cerebellar hemangioblastomas: morphological and immunohistochemical studies.

Two thorium dioxide-induced murine hemangioendotheliomas, 42021 TCT and 44347 TST, were grown subcutaneously (for up to 22 and 15 passages respectively) or intracranially (single passage) and were adapted to culture as a monolayer and, in a limited fashion, in an organ culture system or in rotary suspension. They remained viable and malignant following 20-21 years of storage in liquid nitrogen, and had ultrastructural similarities to human hemangioblastomas. The murine tumors were positive for Griffonia (Bandeiraea) simplicifolia isolectin B4 binding, establishing their endothelial nature; however, unlike human hemangioblastic tumors, they did not cross-react with antisera to human factor VIII or fibronectin and they did not demonstrate Ulex europaeus type I lectin (UEA I) binding (as is also the case for non-neoplastic murine vascular endothelial cells). A variety of morphological cell types in cultures derived from the tumors were also positive for Griffonia (Bandeiraea) simplicifolia isolectin B4 binding. Both murine hemangioendotheliomas, when implanted in the cerebrum, were potent inducers of reactive gliosis, but there was no evidence of uptake of glial fibrillary acidic protein. Unlike the human cerebellar hemangioblastomas, murine tumors were malignant and invasive and did not contain stromal cells, nor did they demonstrate Weibel-Palade bodies or extensive pinocytotic activity. Thus, the murine tumors appear to more closely resemble angiosarcomas or epitheloid hemangioblastomas than the cerebellar hemangioblastomas.

Animals↗
PubMed1992

Evaluation of four serological tests for bovine paratuberculosis.

The standard complement fixation (CF) test, a commercial agarose gel immunodiffusion (AGID) test (ImmuCell Corporation, Portland, Maine), and two commercial enzyme-linked immunosorbent assays (ELISAs; Allied Laboratories, Glenwood Springs, Colo. [Allied ELISA], and the CSL, Limited, [Parkville, Victoria, Australia] enzyme immunoassay [CSL ELISA]) were evaluated by using sera from the Repository for Paratuberculosis Specimens. The case definition of subclinical bovine paratuberculosis was isolation of Mycobacterium paratuberculosis from fecal samples or internal organs of dairy cattle without diarrhea or weight loss. Animals designated as free of the disease originated exclusively from certified paratuberculosis-free herds in Wisconsin. None of the cattle evaluated had been vaccinated for paratuberculosis. Among 177 M. paratuberculosis-infected cattle, the CF test, the AGID test, the Allied ELISA, and the CSL ELISA had test sensitivities of 38.4, 26.6, 58.8, and 43.4%, respectively, and specificities of 99.0, 100.0, 95.4, and 99.0%, respectively. Only 108 of the infected cattle were confirmed by culture or by a commercial DNA probe (IDEXX Corporation, Portland, Maine) to be shedding the organism in fecal samples at the time of serological testing. Among the 108 M. paratuberculosis fecal shedders, the CF test, the AGID test, the Allied ELISA, and the CSL ELISA were positive for 54.6, 40.7, 65.7, and 56.5% of the cows, respectively; and among the 69 cows that were nonshedders, the tests were positive for 14.5, 4.3, 47.8, and 24.6% of the cows, respectively. There was a significant difference (P < 0.05) in the rate of positive test results for all four tests between these two groups of animals. The CF test performed well when it was compared with the other serological tests if a titer of >/- 1.8 was classified as a positive test result.

Animals↗
PubMed1992

Serological and microbial survey of Mycoplasma gallisepticum in wild turkeys (Meleagris gallopavo) from six western states.

From 1986 to 1989, sera from wild turkeys (Meleagris gallopavo), including three subspecies (M. gallopavo intermedia, M. gallopavo merriami and M. gallopavo mexicana) trapped in six western states were tested for antibody to Mycoplasma gallisepticum (MG) (n = 724), M. synoviae (MS) (n = 461) and M. meleagridis (MM) (n = 354) using the rapid plate agglutination (RPA) assay. Subsamples of these sera were also evaluated using the hemagglutination inhibition (HI) assay for antibody to MG (n = 664) and MS (n = 403). Attempts were made to isolate mycoplasmas by swabbing the trachea and cloaca of 190 live wild turkeys and from various tissues (sinus, nasal turbinates, trachea, lung, ovaries and oviduct) from 76 turkeys at necropsy. Isolates were identified using an immunobinding assay. Seroprevalence of MG, MS and MM in the RPA test was highly variable among years and geographic sites, ranging from 0 to 85%, 0 to 87%, and 0 to 83%, respectively, for each mycoplasma species. Of the 724 wild turkey sera tested, 200 (28%) were positive using the RPA assay, while only 20 (3%) of 664 sera tested using the HI assay were positive (at a titer greater than/= 1:80) for antibody to MG. Of the 461 sera tested 178 (39%) were RPA positive for MS, whereas none of the 403 samples tested by HI were positive for MS. Antibody to MM was detected in 72 (20%) of 354 turkey sera tested by RPA. Mycoplasmas were cultured from 81 (30%) of 266 wild turkeys, including 48 that were sampled live and 33 that were examined by necropsy. Mycoplasmas were isolated from every population in which culture was attempted. M. gallopavonis (MGP) was isolated from 37 (46%) of 81 birds which yielded mycoplasma, representing seven of 12 populations sampled. MG was isolated from lower respiratory tissues of one Rio Grande wild turkey trapped in Texas. M. synoviae was isolated from five of 16 Merriam's wild turkeys trapped in Arizona. Sera of birds from which MG or MS was isolated were positive to the respective antigen in the RPA test, but were negative by the HI assay. The RPA test was effective in identifying MG and MS infected turkeys despite lack of confirmation by the HI test. These data suggest that apparently healthy wild turkeys can carry pathogenic mycoplasmas and the currently used field test (RPA) can identify culture positive wild turkeys. Serological screening using the RPA test should be conducted on all wild turkeys prior to relocation.

Age Factors↗
PubMed1992

Basic principles of laboratory medicine.

In order to successfully apply laboratory tests to the solution of clinical problems, a clinician needs to select tests that are appropriate to the suspected disease, collect and submit the necessary specimens, and recognize sources of variation that affect test results. The clinician must have confidence in the accuracy and precision of analytical methods used to produce results. An understanding of reference ranges and test performance in healthy and diseased animals is necessary for accurate interpretation and clinical decision making.

Animals↗
PubMed1991

Adherence to bovine neutrophils and suppression of neutrophil chemiluminescence by Mycoplasma bovis.

The adherence of viable and heat-treated Mycoplasma bovis to bovine peripheral blood neutrophils was studied by specific immunofluorescence staining and flow cytometry. Viable and heat-treated M. bovis cells, adhered to bovine neutrophils in dose-dependent fashion within a 30 min incubation. Fluorescence quenching using crystal violet indicated that unopsonized M. bovis cells remained on the surface of bovine neutrophils without experiencing significant ingestion. The effect of M. bovis adherence on neutrophil microbicidal function was examined by measuring luminol enhanced chemiluminescence (CL). Adherent M. bovis cells did not elicit a bovine neutrophil CL response over a 75 min incubation period. M. bovis inhibited the capacity of bovine neutrophils to mount a CL response. Inhibition occurred whether viable or heat-treated M. bovis cells were used and it occurred when neutrophils were stimulated with opsonized zymosan (OZ) or phorbol myristate acetate (PMA). Inhibition of the PMA stimulated neutrophil CL response required cytadherence by M. bovis cells. These findings suggest that activation of the bovine neutrophil respiratory burst was inhibited at or distal in the pathway to the activation of protein kinase C (PKC), the site of PMA stimulation, and that it was mediated by a direct interaction between the adhering M. bovis cells and the bovine neutrophil membrane.

Animals↗
PubMed1991

Habits of nervous tension and suicide.

In a prospective study of 1,046 male medical students, those who later committed suicide showed a heightened sensitivity in stressful situations as assessed by the Habits of Nervous Tension Questionnaire (HNT). Survival analyses specified 2 of the 25 HNT items as the strongest suicide predictors: Irritability (relative risk 5.5; 95% confidence interval 1.76-17.17) and Urinary Frequency (3.3; 1.07-10.32). No other risk factors for suicide emerged from family background measures or individual medical school measures. It appears that types of sensitivity reflect psychological characteristics that are long-term precursors of suicide.

Adult↗
PubMed1991

Familial and psychological predictors of cancer.

The hypothesis that the quality of human relationships is a component in the development of cancer was investigated in a prospective study of former medical students. Findings from two psychological measures are presented: the Closeness to Parents Scale, which showed that students who subsequently developed cancer were more likely to describe a lack of closeness with their parents than their healthy classmates; and the Rorschach Interaction Scale, which demonstrated less satisfactory relationships among male cancer victims as contrasted with the rest of the cohort. The findings suggest that internal self-other representations, as measured by these two tests, are involved as regulators of biologic systems and manifestations of illness, such as cancer.

Attitude↗
PubMed1990

Epizootiologic patterns of diabetes mellitus in cats: 333 cases (1980-1986).

Medical records from 333 cats with diabetes mellitus were studied retrospectively, using epidemiologic methods to determine the incidence of and risk factors for diabetes mellitus in this species. Abstracts were derived, using the Veterinary Medical Data Program with its 17 participating academic institutions in the United States and Canada. A reference population of 135,651 cats was derived from the same hospital population and time span (July 1980 to June 1986). The incidence of diabetes mellitus in cats was determined to be 2.45 cases/1,000 cat-years-of-risk during the 6-year study period. Breed had no detectable effect on risk for diabetes mellitus. In contrast, body weight, age, gender, and neutering had a significant (P less than or equal to 0.01) effect. Body weight of cats was categorized as being less than or greater than or equal to 6.8 kg. The higher body weight, probably indicating obesity, contributed a 2.2-fold increase in risk, even after adjustment for age and gender (adjusted odds ratio). The etiologic fraction for high body weight was 3.8%, suggesting that an estimated 3.8% of cases of diabetes mellitus was attributable to this factor alone. Over 50% of diabetic cats were greater than 10 years old, and the etiologic fraction for age greater than 7 years alone was 73.5%. Age was a significant (P less than 0.001) and the most important single risk factor for development of the disease in cats, with adjusted odds ratios of 8.3 and 14.4 for age 7 to 10 years and greater than 10 years, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Mycoplasma bovis suppression of bovine lymphocyte response to phytohemagglutinin.

The effect of viable Mycoplasma bovis on the in vitro bovine peripheral blood lymphocyte response to phytohemagglutinin (PHA) was studied. Results showed that M. bovis did not act as a mitogen for bovine lymphocytes. Viable M. bovis produced a dose and time dependent suppression of the PHA stimulated lymphocyte response. Suppression was not a result of differences in the viability of infected or control lymphocyte cultures. The suppressive effect of M. bovis was found to be independent of the concentration of PHA used in the test and the lymphocyte response could not be restored by supplementation of the culture medium with arginine. Delay for 48 h after PHA stimulation before adding M. bovis to the lymphocyte cultures diminished, but did not prevent, the suppression of the lymphocyte response. These results show that suppression of the lymphocyte response does not require the presence of M. bovis during the period of PHA stimulation, and that M. bovis was capable of interrupting [3H]-thymidine incorporation in lymphocytes which were actively synthesizing DNA.

Animals↗
PubMed1990

Evaluation of a commercial staphylococcal bacterin for management of idiopathic recurrent superficial pyoderma in dogs.

Twenty-one dogs with idiopathic superficial recurrent pyoderma were entered into a double-blind, placebo-controlled study to evaluate the efficacy of a commercial staphylococcal bacterin. The study spanned an 18-week period. All dogs were administered sodium oxacillin orally for the initial 6 weeks of the study. Dogs were given the bacterin or placebo SC, twice weekly at 3- or 4-day intervals, beginning at week 0 and continuing for 18 weeks. Dogs given antibiotics plus the bacterin (n = 13) had a significantly (P less than 0.05) better treatment response than those given antibiotic plus placebo.

Animals↗
PubMed1989

Ipsilateral sternoclavicular dislocation and clavicle fracture.

A case of ipsilateral distal clavicle fracture and sternoclavicular joint dislocation is reported. This combination of injuries results from two separate forces in sequence. Closed reduction of the dislocation was possible only after open reduction and internal fixation of the clavicle fracture was performed, because of the inability to manipulate the free-floating segment. Patients should be carefully examined for associated brachial plexus injuries.

Adult↗
PubMed1989

Cardiovascular reactivity to the cold pressor test as a predictor of hypertension.

Cardiovascular reactivity to stress is hypothesized to be a marker for subsequent neurogenic cardiovascular disease, but few prospective studies of this hypothesis are available. We studied 910 white male medical students who had their blood pressure and pulse rate measured before and during a cold pressor test in the years 1948-1964. Hypertensive status (requiring drug treatment) was ascertained by annual questionnaires in the 20- to 36-year follow-up period. An association was observed between maximum change in systolic blood pressure and later hypertension, with a cumulative incidence of hypertension by age 44 of 6.7%, 3.0%, and 2.4% for a change in systolic blood pressure in the upper, middle two, and lowest quartiles, respectively (Kaplan-Meier, p less than 0.02). After adjustment for study entry age, Quetelet Index, cigarette smoking, pretest systolic blood pressure, and paternal or maternal history of hypertension in a Cox model, the association persisted. The excess risk associated with systolic blood pressure reactivity was not apparent until the population aged some 20 years and was most apparent among those in whom hypertension developed before age 45 (relative risk = 2.5, 95% confidence intervals = 1.47, 4.71 for a 20 mm Hg change). Diastolic blood pressure and heart rate changes were not associated with later hypertension. These data suggest that persons prone to later hypertension manifest an altered physiology at a young age.

Adult↗
PubMed1988

Epidemiologic and immunologic evaluation of an outbreak of canine blastomycosis.

Five confirmed cases of canine blastomycosis occurred over the 10-month period of December 1983 to September 1984 in a south-eastern Wisconsin colony of 30 dogs maintained for sled competition. Contrary to other published reports of canine blastomycosis, the sex-specific attack rates were higher among females than males. Four of the five confirmed cases and all four deaths occurred among young female dogs. Differences in the age distribution and/or the micro-environment of the females may have contributed at least in part to the difference in sex-specific attack rates. The serologic response and leukocyte function of the clinically affected and apparently healthy dogs from this colony were assessed during the outbreak. A survey of the adult dogs in the colony suggested that the mitogen-induced lymphocyte blastogenesis of dogs with clinical signs of blastomycosis was suppressed compared with that of dogs that remained free of clinical signs. In contrast to previous reports that autologous sera from dogs and humans with clinical blastomycosis inhibited mitogen-induced lymphocyte blastogenesis, lymphocyte responsiveness was similar to, or greater in the presence of autologous canine serum than it was in the presence of fetal bovine serum.

Animals↗