PubMed Health⌕ Search

Biomedical subjects

C L Brown

Publications and source records attributed to C L Brown.

At least 19 recordsLinked to original sources
PubMed1992

Background and methods for the lovastatin restenosis trial after percutaneous transluminal coronary angioplasty. The Lovastatin Restenosis Trial Study Group.

Restenosis remains a critical limitation of percutaneous transluminal coronary angioplasty (PTCA). Recent experimental and clinical data have suggested that lovastatin, an hydroxymethylglutaryl coenzyme A reductase inhibitor, may reduce the rate of restenosis through reduction of low density-lipoprotein (LDL) cholesterol or possibly by direct effects. Lovastatin may therefore produce favorable alterations in endothelial healing, resulting in a decreased smooth muscle cell proliferative response to injury after angioplasty. Emory University, in conjunction with Merck Research Laboratories, has initiated a 10-center double-blinded, placebo-controlled, randomized trial to assess the effect of both pretreatment and aggressive lipid lowering with lovastatin in reducing the rate of restenosis. Lovastatin achieves approximately 75% of its effect on LDL cholesterol by 1 week. Thus, patients scheduled for PTCA are randomly assigned pretreatment with lovastatin, 40 mg twice daily, or placebo 7 to 10 days before PTCA. Therapy is continued for 6 months, at which time repeat coronary arteriography is performed. A detailed safety algorithm was designed, with patients receiving lovastatin and matching placebo back-titrated on a 1:1 basis for LDL cholesterol less than 50 mg/dl. The power is a 90%, alpha = 0.05, 2-tailed test to reduce restenosis from 30 to 15%. The sample size is 360 patients in the 2 arms; allowing for a 10% dropout rate, approximately 400 patients will be randomized. Patients with successful PTCA, less than 50% residual diameter stenosis and greater than or equal to 20% diameter stenosis reduction are analyzed for restenosis at 4 to 6 months by quantitative coronary arteriography.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1992

Asynchrony of changes in tissue and plasma thyroid hormones during the parr-smolt transformation of coho salmon.

The relationship between plasma thyroid hormone concentrations and the thyroid hormone concentrations in selected tissues was examined throughout the spring during the typical course of parr-smolt transformation in coho salmon (Oncorhynchus kisutch) in fresh water and also in coho salmon moved prematurely to seawater. The thyroid hormones thyroxine (T4) and triiodothyronine (T3) were extracted from brain, liver, and muscle tissue. The T4 and T3 concentrations in the extracts and plasma were measured by radioimmunoassay. The peak in plasma T4 occurred in late April; however, the concentration of T4 in the brain and liver increased before levels of T4 in plasma increased. During the rise in plasma T4, the T4 content in muscle decreased. Plasma T3 concentrations were unchanged in March and April, but decreased in May. Transfer to seawater eliminated the late April peak in plasma T4 levels, indicating suppressed thyroid activity; however, the tissues of salmon in seawater contained more T3 than tissues of salmon in fresh water at this time. These findings indicate complex peripheral regulation of thyroidal status in this teleost and represent the first bridge between compartmental models of thyroid hormone kinetics and actual measurement of tissue pools of thyroid hormones in an ectothermic vertebrate. In summary, tissue concentrations of thyroid hormones did not echo plasma concentrations, indicating that thyroidal status cannot be inferred from plasma data alone.

Aging↗
PubMed1992

Coxsackievirus B4 infection of the mouse pancreas: acute and persistent infection.

The course of infection of a pancreas-adapted isolate of coxsackievirus B4 was followed over a 10 month period in a murine model. Following intraperitoneal inoculation a typical acute infection was seen in nine of 10 inbred mouse strains. Virus rapidly infected the exocrine pancreas, titres peaking 3 to 4 days post-infection (p.i.). Lesions were almost exclusively confined to pancreatic acinar cells and varied in severity among the inbred strains. Virus shed into the blood-stream was not cell-associated. Evidence of persistent infection was found in nine mouse strains and infective virus was recovered from the pancreas of seven strains for up to 10 months p.i. Approximately 28% of pancreases examined beyond the acute phase showed focal inflammation and 22% showed focal necrosis (cell death). Virus was occasionally recovered from other organs (heart, liver and spleen), but lesions were rarely seen. Virus-specific antigen was localized to small groups of pancreatic acinar cells using an indirect immunogold silver staining technique. These observations suggested that the virus persists in pancreatic tissues because it seems unlikely that virus disseminated from distant sites would cause such localized infection. In three of these strains, the course of infection may have been influenced by superinfection with mouse hepatitis virus.

Acute Disease↗
PubMed1992

Campus attitudes toward alcohol and drugs in a deep southern university.

In our zeal to deal with alcohol and drug abuse, we may have a distorted picture of what the majority of college students actually think about alcohol and drug use. Students in this study done at a public university located in the Deep South report being generally intolerant of substance abuse.

Alcohol Drinking↗
PubMed1991

Abnormalities of the EGF receptor system in human thyroid neoplasia.

The epidermal-growth-factor receptor (EGF-r) and its ligands are involved in the control of proliferation of both normal and neoplastic thyroid epithelium. Autocrine stimulation of growth involving this receptor system has been identified in several types of human neoplasia and we were interested to determine whether it might occur in human thyroid tumours. We have therefore examined an archival series of thyroid tumours and non-neoplastic pathologies for expression of the EGF-r and 2 of its ligands, transforming growth factor alpha (TGF-alpha) and epidermal growth factor (EGF), using immunohistochemistry. We found evidence of expression of both the EGF-r and the TGF-alpha in the majority of thyroid tumours, with a trend to higher expression in more malignant neoplasms. We also found variable levels of expression of EGF-r and TGF-alpha in all cases of thyroiditis examined. We conclude that there is a potential autocrine loop involving the EGF-r system in both neoplastic and non-neoplastic conditions of the human thyroid.

Adenocarcinoma↗
PubMed1991

Coxsackie virus B4 infection of the mouse pancreas: I. Detection of virus-specific RNA in the pancreas by in situ hybridisation.

The pathology of Coxsackie virus B4 (CVB4) infection in a murine model was investigated by in situ hybridisation using a biotinylated cDNA probe derived from CVB4. During the acute phase of infection virus RNA sequences were detected in the exocrine pancreas of 60% of mice infected with a pancreotropic variant of CVB4. A positive hybridisation signal was observed in other organs in some animals including the heart and liver of 1 mouse 28 days after infection. The cellular distribution of virus RNA sequences corresponded well with the histological findings in most tissues. Possible causes for failure of hybridisation in some infected pancreases are discussed in conjunction with potential application of the technique in human pancreas biopsy samples.

Animals↗
PubMed1991

Activating point mutations of the gsp oncogene in human thyroid adenomas.

The gene for the alpha polypeptide chain (alpha s) of the heterotrimeric G protein Gs can be activated to the putative oncogene gsp by specific point mutations at codons 201 and 227. Such mutations have been reported in 40% of human growth hormone-secreting pituitary adenomas and in a single autonomously functioning thyroid adenoma. We examined an archival series of 45 differentiated human thyroid tumors by polymerase chain reaction amplification and oligonucleotide hybridization to identify point mutations at each of the affected codons. Successful amplification was achieved in 38 cases, and activating mutations were identified in 5 of 13 (38%) autonomously functioning adenomas, but in none of 16 nonfunctioning adenomas, six papillary carcinomas, or three follicular carcinomas. Our results confirm that the gsp oncogene is involved in the pathogenesis of autonomously functioning tumors but do not support a role in other thyroid tumors.

Adenoma↗
PubMed1991

Respirator physiology research: answers in search of the question.

Adverse effects of respirators have been the focus of considerable research over the past decade. Individual research projects have generally focused on one specific category of effects: ventilatory, respiratory control, work limitation, subjective discomfort, psychologic effects, thermal loading, and cardiovascular changes. Most were studied in experimental laboratory situations rather than in actual worksites. Very little attention has been given to compliance with use and actual effectiveness in preserving health. Inasmuch as many types of effects have been demonstrated, there is a need to carefully define which type(s) of effects is/are most important for respirator design selection and worker medical certification in particular situations. In general, respirators should be assessed for their effect on all relevant variables.

Adaptation, Physiological↗
PubMed1991

Outcomes of power development in work relationships.

Nurse executives who routinely feel overpowered in their work relationships are highly stressed. When high levels of stress are experienced regularly, ill health may be the outcome, resulting in negative consequences for both the nurse executive and the organization. Strategies are proposed for nurse executives to use in coping with consistent patterns of work-related overpowerment.

Adaptation, Psychological↗
PubMed1990

The effect of perindopril and hydrochlorothiazide alone and in combination on blood pressure and on the renin-angiotensin system in hypertensive subjects.

The pharmacodynamic effects and acceptability of perindopril (4 mg daily) and hydrochlorothiazide (25 mg daily) given alone or in combination for 1 month were investigated in a double-blind, placebo controlled, parallel group study. The pharmacokinetics of perindopril and its active metabolite perindoprilat and the time course of angiotensin converting enzyme inhibition were studied for 72 h following the last dose of treatment in the two appropriate groups. Similar decreases in blood pressure were seen 24 h after the last dose of perindopril or hydrochlorothiazide (11/7 mm Hg supine) given alone at these doses. The effect of these drugs given together was additive on diastolic blood pressure and synergistic on systolic blood pressure (24.5/12.6 mm Hg supine) taking into account the placebo response. The significant increase in plasma renin activity produced by perindopril alone was potentiated by concurrent administration of hydrochlorothiazide. The formation of perindoprilat was slightly reduced in the group also receiving hydrochlorothiazide and there was a very small reduction in ACE inhibition in this group. Perindopril, whether given alone or in combination with hydrochlorothiazide, was well tolerated and produced no clinically significant change in routine haematology or serum biochemistry. The additive or synergistic effects of perindopril and hydrochlorothiazide on blood pressure must be due to their complementary physiological actions and not to a pharmacokinetic interaction.

Adult↗
PubMed1990

Absence of abnormalities of the c-erbB-1 and c-erbB-2 proto-oncogenes in human thyroid neoplasia.

The c-erbB-1 and c-erbB-2 proto-oncogenes are frequently activated by gene amplification and overexpression in a variety of human cancers. In an analysis of a large series of benign and malignant thyroid tumours, no abnormalities of structure or expression of either of c-erbB-1 or c-erbB-2 were found. Activation of these oncogenes is not a necessary event in neoplasia of this epithelial system.

DNA, Neoplasm↗
PubMed1990

Impact of conventional and three-dimensional thallium-technetium scans on surgery for primary hyperparathyroidism.

Twenty-nine patients with primary hyperparathyroidism underwent double-tracer subtraction scanning after injection of 201Tl as thallous chloride for thyroid and parathyroid images followed by 99mtechnetium as sodium pertechnetate for thyroid images prior to surgical exploration of the neck. The operative findings were correlated with the scans. All 23 adenomas (100%) and 13 of 18 (72%) hyperplastic glands were correctly localized. The ability of the scan to identify abnormal parathyroids was determined by the gland mass rather than whether the tissue was adenomatous or hyperplastic as all 32 (100%) abnormal glands weighing more than 180 mg were successfully localized in contrast to four of nine (44%) glands weighing less than 180 mg. An additional technique, in which emission tomography was carried out after subtraction scintigraphy, was used on 11 patients in the series. In all 11, the site of a single abnormal gland was predicted by the conventional subtraction scan: in nine of these patients, emission tomography provided additional localization of the gland in the anteroposterior plane.

Humans↗
PubMed1990

Vaccination of free-ranging Pennsylvania raccoons (Procyon lotor) with inactivated rabies vaccine.

Thirty-nine free-ranging raccoons (Procyon lotor) in an endemic rabies area of Pennsylvania (USA) were vaccinated with a single intramuscular inoculation of commercial inactivated rabies virus vaccine, 17 June to 23 August 1987. Paired serum samples, pre- and postvaccination, were obtained from eight raccoons and were analyzed in vitro for rabies virus neutralizing antibody using a modified rapid fluorescent focus inhibition test. Seven of eight (88%) recaptured raccoons demonstrated seroconversion within 15 to 26 days of vaccination. At 1 yr postvaccination, three vaccinated raccoons were recaptured and challenged in captivity with street rabies virus, resulting in the death of two of three vaccinates and five of five unvaccinated control raccoons.

Animals↗