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Biomedical subjects

W J Thomas

Publications and source records attributed to W J Thomas.

At least 19 recordsLinked to original sources
PubMed2000

Anomalous left anterior descending coronary artery: malignant hospital course of a not so benign anomaly.

Anomalous origin of the left anterior descending coronary artery from the right sinus of Valsalva has been described as a benign anomaly. Typically it takes one of two courses, intraseptal or prepulmonic (though pre-aortic and retro-aortic courses also have been described). We describe the treatment of a patient with prepulmonic route and a malignant course before revascularization.

Adult↗
PubMed2000

Infected endovascular stents managed with medical therapy alone.

More than 400,000 endovascular stents are put in place in the United States annually. Infectious complications have been reported in fewer than one in 10,000 cases. It remains unclear whether the optimal management strategy for these patients is with medicine alone or surgery. We report two cases of endovascular stent infections that were treated successfully with antibiotics alone.

Aged↗
PubMed2000

The effect of long-acting injectable selenium formulations on blood and liver selenium concentrations and liveweights of red deer (Cervus elaphus).

AIM: To evaluate the efficacy of a new long acting injectable selenium ( Se ) formulation to increase the Se status and prevent Se deficiency in red deer. METHODS: Groups of weaned red deer (four stags and six hinds/group) grazing pastures containing <30 mg Se/kg DM were injected subcutaneously with either 0.5, 1.0 or 2.0 mg Se/kg as a new formulation of BaSeO4 (Deposel Multidose), 1.0mgSe/kg of a current formulation (Deposel), or not treated. Blood Se concentrations and liveweight were measured nine times at intervals over 377 and 270 days, respectively. RESULTS: Both formulations of Se elevated blood Se concentrations from 105 nmol/l pre-injection for at least 377 days with peak levels of 1894, 1395 and 818 nmol/l for high, medium and low doses of Deposel Multidose, respectively, at 73141 days, and 1508 nmol/l at 73-141 days for the medium dose of Deposel, which persisted at similar levels for the duration of the study. Deposel Multidose produced fewer and less severe subcutaneous tissue reactions than Deposel. Pastures contained 10 to 30 mg Se/kg DM. There was no significant difference in growth rate between treated and control deer. There was a significant (p<0. 01) linear relationship (y = 1.25x + 71.6, R2=0.86) between blood (x) and liver (y) Se concentrations in the range of 120 - 2100 nmol/l for blood concentrations, and 200 - 3000 nmol/kg for liver concentrations. CONCLUSION: Injections of BaSeO4 in both formulations studied were effective in increasing the Se status of deer but the new formulation produced fewer and less-severe tissue reactions. Young growing red deer appear less sensitive to Se deficiency as measured by weight gain, than sheep and cattle, suggesting that reference ranges for those species are not appropriate for deer. There was a linear correlation between blood and liver selenium concentrations.

Journal Article↗
PubMed1998

Similar feeding patterns are induced by perifornical neuropeptide Y injection and by food deprivation.

Although hypothalamic injections of neuropeptide Y (NPY) induce robust feeding, there is little information about the patterns of feeding elicited by this peptide. To reveal these patterns, NPY (0, 8, 24, 78, 235 pmol/10 nl) was injected into the perifornical hypothalamus (PFH) of satiated adult male rats and their subsequent food intake was monitored every minute for 24 h. For comparison, feeding patterns were similarly observed following fasts of 0, 3, 6, 9, 12, and 24 h. The results demonstrated that NPY and food deprivation both produced dose- or deprivation-dependent increases in food intake that were most evident in the first 6 h. The increased intakes induced by NPY were characterized by combinations of increased meal size and frequency, with the predominant effects being increases in the size of and decreased latency to eat the first meal. Similarly, fasting progressively increased food intake by combinations of increased meal size and frequency, with the predominant effects being increases in the size of and decreased latency to eat the first meal. These similarities between NPY-induced and food deprivation-induced feeding are consistent with a stimulatory role for endogenous NPY in deprivation-induced feeding. These findings also suggest that NPY may increase eating by acting on mechanisms of both meal initiation and of meal termination.

Animals↗
PubMed1997

DNA synthesis and cell proliferation in C6 glioma and primary glial cells exposed to a 836.55 MHz modulated radiofrequency field.

We have tested the hypothesis that modulated radiofrequency (RF) fields may act as a tumor-promoting agent by altering DNA synthesis, leading to increased cell proliferation. In vitro tissue cultures of transformed and normal rat glial cells were exposed to an 836.55 MHz, packet-modulated RF field at three power densities: 0.09, 0.9, and 9 mW/cm2, resulting in specific absorption rates (SARs) ranging from 0.15 to 59 muW/g. TEM-mode transmission-line cells were powered by a prototype time-domain multiple-access (TDMA) transmitter that conforms to the North American digital cellular telephone standard. One sham and one energized TEM cell were placed in standard incubators maintained at 37 degrees C and 5% CO2. DNA synthesis experiments at 0.59-59 muW/g SAR were performed on log-phase and serum-starved semiquiescent cultures after 24 h exposure. Cell growth at 0.15-15 muW/g SAR was determined by cell counts of log-phase cultures on days 0, 1, 5, 7, 9, 12, and 14 of a 2 week protocol. Results from the DNA synthesis assays differed for the two cell types. Sham-exposed and RF-exposed cultures of primary rat glial cells showed no significant differences for either log-phase or serum-starved condition. C6 glioma cells exposed to RF at 5.9 muW/g SAR (0.9 mW/cm2) exhibited small (20-40%) significant increases in 38% of [3H]thymidine incorporation experiments. Growth curves of sham and RF-exposed cultures showed no differences in either normal or transformed glial cells at any of the power densities tested. Cell doubling times of C6 glioma cells [sham (21.9 +/- 1.4 h) vs. field (22.7 +/- 3.2 h)] also demonstrated no significant differences that could be attributed to altered DNA synthesis rates. Under these conditions, this modulated RF field did not increase cell proliferation of normal or transformed cultures of glial origin.

Animals↗
PubMed1993

The perifornical area: the major focus of (a) patchily distributed hypothalamic neuropeptide Y-sensitive feeding system(s).

Neuropeptide Y (NPY), a neurochemical found in high concentrations within hypothalamic neurons, is believed to participate in the control of eating behavior and body energy balance and elicits a powerful eating response when injected into the hypothalamus. To delineate precisely the locus of this effect, NPY (78 pmol) or its artificial cerebrospinal fluid vehicle was injected in the extremely small volume of 10 nl through chronic guide cannulae into an array of 47 different hypothalamic areas in satiated rats and the elicited food intake was measured. To determine the anatomical resolution of this technique, the spread and recovery of [125I]NPY injected in 10 nl was also assessed. Results indicate that as much as 95% of the injected label was recovered within the brain tissue and guide cannulae and that 100% of the tissue label was localized to within 0.8 mm of the injection site. Behavioral results show that the perifornical hypothalamus (PFH), at the level of the caudal paraventricular nucleus, is the most sensitive hypothalamic site for NPY-induced eating. NPY there elicited mean increases in food intake of 12.5 g over baseline at 1 h and 20.0 g at 4 h postinjection. Injections bracketing the PFH in all directions were substantially less effective. Additionally, significant effects were also observed in at least seven other sites that were distributed throughout the hypothalamus. These findings suggest both that the PFH may be the primary hypothalamic site containing feeding-related NPY-sensitive receptors and that other sites distributed within the hypothalamus also can mediate NPY's effects.

Analysis of Variance↗
PubMed1993

Effect of 72 Hz pulsed magnetic field exposure on ras p21 expression in CCRF-CEM cells.

CCRF-CEM T-lymphoblastoid cells have been exposed to an asymmetric electromagnetic signal pulsed at 72 Hz for up to 28 hr. Following exposure, cells were lysed and extracted, and the extract was electrophoresed on SDS-polyacrylamide gels. Proteins were electroblotted onto nitrocellulose membranes and the product of the ras proto-oncogenes, p21, was identified and quantitated by successive treatment with pan ras p21 antibody, second antibody-alkaline phosphatase conjugate, and enzyme substrate. No changes in p21 levels were observed for the first 6 h of electromagnetic field exposure as compared to unexposed control cells. However, from 6-16 h exposure, p21 levels in exposed cells decreased linearly to only 30% of control values. From 16-28 h exposure, p21 levels in exposed cells increased nearly linearly to control cell values. Slot-blot analysis indicated that altered p21 protein expression is a result, at least in part, of changes in the levels of N-ras mRNA. No concomitant changes were detected in either cyclic AMP levels or in the expression of cell surface markers. While the significance of the marked reduction in cellular p21 is unclear, it does not appear to be related to cell differentiation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1993

Hepatitis A virus anicteric encephalitis coexistent with hepatitis C virus infection.

A 34-yr-old male presented with acute encephalitis. The encephalitis was due to an anicteric hepatitis A virus infection superimposed upon coexistent hepatitis C virus infection. Neurologic syndromes due to hepatitis A virus infection have all been associated with jaundice. Neurologic complications of hepatitis C virus infections have not been described. Identification of hepatitis A virus as an etiology of viral encephalitis can reduce the need for extensive costly evaluations, and unnecessary empiric antibiotics. Further clinical experience will determine if hepatitis C virus produces neurologic manifestations.

Acute Disease↗
PubMed1992

Magnetic field-induced changes in specific gene transcription.

Magnetic fields are physical, environmental agents that have been shown to produce a variety of responses in cellular and animal studies, including general changes in gene transcription. In this study, the nuclear run-off assay has been employed to assess alterations in specific gene transcription in CEM-CM3 T-lymphoblastoid cells exposed for 15-120 min to a 1 gauss sinusoidal magnetic field at 60 Hz. Time-dependent and cell density-dependent changes in the transcription of c-fos, c-jun, c-myc and protein kinase C (beta-form) have been observed and quantitated. Additionally, changes in transcript levels, assessed by slot-blot analysis, have been found to parallel the changes in gene transcription. These data suggest an important role for magnetic field exposure in altering cellular processes.

Cell Line↗
PubMed1989

Malignant schwannoma of the clitoris in a 1-year-old child.

A 1-year-old infant with von Recklinghausen's neurofibromatosis was seen because of increasing clitoral enlargement over a 7-month period. The mother, who also had neurofibromatosis, was treated 2 years beforehand for an acoustic neuroma. The child was treated by radical clitorectomy. Pathologic examination revealed malignant schwannoma, a tumor not previously described in this site. Vincristine, dactinomycin, and cyclophosphamide chemotherapy was given for 2 years to prevent local recurrence and metastatic spread. The child remains tumor free 2.5 years after diagnosis.

Clitoris↗