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K O'Brien

Publications and source records attributed to K O'Brien.

At least 109 records · Page 6Linked to original sources
PubMed1988

Effects of HIV infection, perceived health and clinical status on a cohort at risk for AIDS.

Data from a general population sample of 621 healthy homosexual men are used to evaluate the social and emotional effects of HIV antibody status, clinical signs detected by medical examination, and subjectively perceived symptoms. Participants are unaware of their serologic status at the time of data collection, thus allowing the effects of the virus to be separated from reactions to the knowledge of serologic status. The data show that seropositivity for HIV is not associated with elevated levels of social or emotional impairment. Clinical signs lead to impairment in baseline data, but these effects do not persist at a second wave. This weakening suggests that the effects are mediated by psychological pathways rather than biologic ones. This suspicion is confirmed in further analyses, which show that the effects of clinical signs are mediated by subjectively perceived symptoms. These results show that neither social nor emotional impairment is likely to be a prodromal sign of HIV infection in otherwise healthy homosexual men. The substantial levels of distress found among these men is more directly influenced by psychological determinants than biologic ones. This suggests that physicians should be aware of the psychological toll imposed on gay men who develop health problems in the current atmosphere of uncertainty regarding risk of AIDS.

AIDS Serodiagnosis↗
PubMed1987

Prevalence of smokeless tobacco use in Pitt County, North Carolina.

The purpose of this study was to estimate the prevalence of smokeless tobacco use in the largest tobacco-producing county in the United States. A 1-in-100 systematic random telephone sample was taken from the county telephone directory. A total of 280 complete questionnaires were obtained. Results indicate that .40 +/- .042 [p +/- SE(p)] males and .09 +/- .024 of females use smokeless tobacco. The point prevalence for the total population was estimated to be .15.

Adolescent↗
PubMed1986

Cytologic results of fine-needle aspiration biopsies of the central nervous system.

The cytologic results of 34 fine-needle aspiration (FNA) biopsies of the central nervous system (CNS) are reported. There were 31 intraoperative biopsies performed at the time of craniotomy. All the cases were diagnosed using direct smear preparations stained with Papanicolaou and Diff-Quik (Harleco, NJ) stains. The sensitivity of the procedure was 90.7%, specificity 100%, positive predictive value 100%, and efficiency of the test of 91%. There were no false-positive diagnoses and three false-negative diagnoses. This study attests to the diagnostic accuracy of FNA cytologic examination of the central nervous system. Statistical analysis of the few previous FNA biopsy series of the CNS are presented. Review of the indications, advantages and complications of CNS needle biopsy are discussed. This report supports the role of fine-needle aspiration cytology in the evaluation of CNS lesions. With recent developments in radiologic imaging, especially ultrasound and computed tomography (CT) using stereotactic guidance, specimens can be obtained for cytologic diagnosis using thinner needles. Excellent diagnostic accuracy can be obtained, as pathologists gain greater familiarity with interpreting FNA biopsy material. Other advantages of FNA biopsy of the central nervous system include the low morbidity and mortality of the procedure and the ability to perform the biopsy through a burr hole under local anesthesia and thereby decrease hospitalization time and cost.

Adult↗
PubMed1985

Detection of two viral genomes in single cells by double-label hybridization in situ and color microradioautography.

Double labeling and color microradioautography were used in a new method of hybridization in situ to identify different genes in individual cells. The method is based on the unequal penetration of 3H and 35S into two layers of nuclear track emulsion separated by a thin barrier film. Hybridization of a 35S-labeled probe specific for one kind of gene results in silver grains over cells in both layers of emulsion; a 3H-labeled probe for a second gene provides grains only in the first layer of emulsion. Silver grains are converted to magenta-colored grains in the first layer and to cyan-colored grains in the second to facilitate enumeration of grains in each layer. This technique should be widely applicable in analyses of differential gene expression in single cells or in discrete populations of cells.

Autoradiography↗
PubMed1984

Can a calcaneal morphologic index determine the degree of osteoporosis?

The proposal that a scoring system of the radiographic trabecular patterns of the os calcis could be related to degree of osteoporosis was tested. The technique fails as it showed no correlation with actual bone density determined by a Compton scatter technique and because of a low level of observer concordance. Possible reasons for the poor performance of the index developed in India when applied to North Americans are discussed.

Age Factors↗
PubMed1984

Glucose affects in vitro maturation of fetal rat islets.

Fetal pancreatic islets (21.5 days old) were cultured in RPMI 1640 containing either 2.8 or 11.1 mM glucose for 7 days. After the 7-day culture period, islets cultured in 2.8 mM glucose demonstrated a minimal first phase of insulin secretion in response to acute glucose stimulation, whereas islets cultured in 11.1 mM glucose demonstrated a biphasic insulin secretory pattern. Islets cultured in 11.1 mM glucose initiated insulin secretion at 4.4 +/- 0.1 mM glucose and plateaued at 11.6 mM glucose when exposed to a linear gradient. In addition, culture in 11.1 mM glucose increased DNA content (P less than 0.01) and [3H]thymidine incorporation (P less than 0.05) in fetal islets. However, ultrastructural morphometric analysis indicated that the actual number of beta-cells within islets cultured in either 2.8 or 11.1 mM glucose did not increase. The insulin contents of islets cultured in 2.8 and 11.1 mM glucose were 0.46 +/- 0.06 and 1.14 +/- 0.10 mU/islet, respectively. During subsequent glucose stimulation, islets cultured in 2.8 and 11.1 mM glucose released 3% and 5.6% of their total insulin content, respectively. Ultrastructural morphometric analysis indicated that 11.1 mM glucose stimulated an increase in the volume of individual beta-cells, i.e. hypertrophy. The hypertrophy of beta-cells within islets cultured in 11.1 mM glucose resulted in a concomitant increase in islet volume. Finally, the hypertrophy of beta-cells within islets cultured in 11.1 mM glucose was a result of increased volumes of mitochondria, secretory granules, and, to the greatest extent, endoplasmic reticulum. These findings indicate that glucose is a potent factor in the maturation of cultured fetal rat islets.

Animals↗
PubMed1983

Metabolic basis of the species difference to aflatoxin B1 induced hepatotoxicity.

Primary metabolism of aflatoxin B1 by the liver microsomal enzymes from a range of animal species showed both quantitative and qualitative differences. Quail was shown to have the most rapid metabolism of aflatoxin B1. The major product of metabolism in this case was found to be aflatoxin B1-8,9-dihydrodiol suggesting that the quail microsomes produced high levels of the proposed reactive intermediate aflatoxin B1-8,9-epoxide. Using this system to generate the epoxide, the ability of the cytosol prepared from each species to conjugate epoxide with reduced glutathione was investigated. Large differences in ability to conjugate were observed ranging from 0 to 72% for quail and mouse respectively. Differences in both primary and secondary metabolism of AFB1 were noted between male and female Fischer 344 rats.

Aflatoxin B1↗
PubMed1981

Flow-cytogenetics. II. High-resolution ploidy measurements in human fibroblast cultures.

high-resolution flow-cytometric measurements of ethidium bromide/mithramycin-stained human fibroblast cultures reveal discrepancies between fluorescence pulse-height distributions and genome size as a function of cell strain, culture conditions, culture age, and proliferative stage. These discrepancies were quantitatively assessed by (1) evaluation of the variation of the widths of the 2c fluorescence pulse-height histogram peaks, (2) comparisons between sample to standard fluorescence ratios of 45,XO and 49,XXXXY cell strains, and (3) comparison of fluorescence intensities among cell populations of identical genome size but differing degrees of chromatin condensation (mitotic vs. nonmitotic cells of diploid and tetraploid cell strains). As in our previous studies with lymphocytes, our results suggest caution in equating fluorescence intensity with "DNA content" in flow measurements of nonhomogeneous cell populations. Conditions of cell culture and sample preparation must be standardized in order to compare "DNA content" differences by flow techniques. Remaining sources of variation presently limit detection to differences in DNA content of greater than 2%.

Cell Line↗
PubMed1981

The St. Thomas' hospital cardioplegic solution: a characterization in two species.

Following detailed investigation and definition of some of the critical factors relating to the composition and use of cardioplegic protective solutions, we have formulated the St. Thomas' Hospital cardioplegic solution number 2. This cardioplegic solution (NaCl 110.0 mM, NaHCO3 10.0 mM, KCl 16.0 mM, MgCl2 16.0 mM, CaCl2 1.2 mM, pH 7.8) is designed for routine clinical use combining optimal protection with simplicity of formulation and administration/infusion. In order to characterize the efficacy of this modified solution, experiments have been carried out in two species: the isolated rat heart and the in-situ dog heart. In parallel protocols, hearts were subjected to ischemic arrest of up to 4 hours. Multidose (every 40 minutes) cardioplegic infusion of the St. Thomas' solution combined with topical hypothermia extended the tolerable period of ischemia from less than 30 minutes to about 120 minutes in the rat and from less than 60 minutes to more than 180 minutes in the dog. These conclusions were based on the measurement of functional indices together with biochemical, cellular chemical and ultrastructural assessments. The studies confirmed the additive protective properties of hypothermia and chemical cardioplegia and the utility of the rat heart model in the assessment of protective interventions.

Animals↗
PubMed1981

Protection of the myocardium during ischemic arrest. Dose-response curves for procaine and lignocaine in cardioplegic solutions.

The dose-response curve of procaine or lignocaine (lidocaine) added to the St. Thomas' Hospital cardioplegic solution was investigated with an isolated working rat heart preparation. In the absence of any cold cardioplegic protection, hearts failed to recover after as little as 30 minutes of ischemia. A single infusion (20 degrees C) of the basic St. Thomas' Hospital cardioplegic solution allowed hearts to recover to 60% or more of their preischemic control aortic flow after a 120 minute period of ischemia. Addition of procaine to the cardioplegic solution either increased or reduced the apparent protective properties of the solution with a bell-shaped dose-response curve being obtained. The optimum procaine concentration was 0.05 mM/L. At this concentration the protection afforded by the St. Thomas' Hospital solution was increased by up to two thirds. Substitution of lignocaine for procaine resulted in a similar dose-response curve with its optimum also at 0.05 mM/L. If a similar optimum exists for the human heart, the doses in current clinical use would appear to be too high. These results argue for determining the dose-response characteristics of all substances used in cardioplegic solutions.

Animals↗