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Biomedical subjects

K O'Brien

Publications and source records attributed to K O'Brien.

At least 109 records · Page 6Linked to original sources
PubMed1993

An outbreak of cholera in Maryland associated with imported commercial frozen fresh coconut milk.

In August 1991, the first outbreak of cholera associated with an imported commercial food product occurred among persons attending a private picnic. An epidemiologic investigation showed infection with toxigenic Vibrio cholerae O1, biotype El Tor, serotype Ogawa, in 4 of 6 persons who had consumed coconut milk imported from Thailand. In addition, the US Food and Drug Administration recovered toxigenic V. cholerae O1, biotype El Tor, serotype Ogawa, from 1 of 6 unopened bags of the same brand (but different shipment) of coconut milk as that consumed by infected persons. Investigation in Thailand of the manufacturing process of the implicated coconut milk showed several sanitary violations, suggesting that contamination had occurred during production. This outbreak suggests a model of entrance of V. cholerae into a population and shows the need to evaluate current methods of maintaining the safety of imported foods in the United States.

Adult↗
PubMed1993

A longitudinal study of psychological distress in a cohort of gay men. Effects of social support and coping strategies.

This study presents analyses on questionnaire data collected from a panel of 520 gay men at risk for acquired immune deficiency syndrome, enrolled in the Coping and Change Study (1985-1987). The data were assessed to determine the association of social support and coping styles with subsequent depression and global distress and to investigate whether these predictors of mental health are stable or transient over time. Three different measures of the subjective, qualitative nature of social support were significantly associated with subsequent mental health. Those who reported a subjective sense of isolation experienced significantly more adverse mental health 6 months later at all three measurement periods. Scattered effects were found for perceived social conflict and perceived social support from others. These results indicate that certain types of social support appear to influence mental health in this cohort and, furthermore, that some associations are transient and others more stable over time.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Using focus groups to develop health surveys: an example from research on social relationships and AIDS-preventive behavior.

Focus group data can inform the choice of words or phrases in a questionnaire, the construction of items to measure a given concept, the formation of new hypotheses, and the development of survey procedures. To date, few examples exist to show researchers in health behavior and health education how they might use focus groups for these purposes. This paper provides an example of group discussions that were held with gay and bisexual men on the topic of their experiences of the human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) epidemic and illustrates the many ways that focus groups assist in questionnaire development.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Coronary heart disease risk factors in morbidly obese women with normal glucose tolerance.

OBJECTIVE--To examine if the risk for CHD increases progressively with increases in the BMI of normoglycemic, hyperinsulinemic, morbidly obese women (BMI > or = 35 kg/m2). RESEARCH DESIGN AND METHODS--Insulin sensitivity was evaluated by calculating an ISI following an OGTT. There was a significant linear relationship between ISI and BMI fitted by two straight lines intersecting at a point corresponding to a BMI of 29.7 +/- 1.5 kg/m2. Significant linear relationships between insulin sensitivity and BMI were obtained below and above this breakpoint. Similarly, a breakpoint for the relation between dBP and BMI corresponding to a BMI > or = 33.7 +/- 3.4 kg/m2 was obtained. Significant linear relationships between BMI and plasma fasting glucose, triglyceride, cholesterol, HDL cholesterol, sBP, or dBP were not observed in the women with a BMI > 35 kg/m2. RESULTS--Compared with lean (BMI < 27) women of similar age, the morbidly obese patients appear to be at a higher risk for CHD. This is suggested by statistically significant increases in fasting insulin (mean +/- SD; 187 +/- 137 vs. 64.2 +/- 16.2 pM) and triglyceride levels (128 +/- 78.1 vs. 73 +/- 25 mg/dl), sBP (132 +/- 114 vs. 104 +/- 15.8) and dBP (84 +/- 72 vs. 67 +/- 2.1 mmHg), and decreases in HDL cholesterol (1.03 +/- 0.44 vs. 1.29 +/- 0.82 mM) and apo A-I (91 +/- 55 vs. 122 +/- 35 mg/dl) concentrations. CONCLUSIONS--It appears that there may be a threshold of body mass up to which insulin sensitivity is associated with CHD risk. Above this threshold, there does not appear to be a progressive increase in the risk factors for CHD with increases in BMI.

Adult↗
PubMed1993

Hospital acquired rota virus infection: the economics of prevention.

Nosocomial rota virus infection results in costs to patients (for example, delayed procedures) and to hospitals (for example, additional bed-days, and ward closures if an epidemic occurs). This paper analyses the economic efficiency of using a preventive measure--a high antibody milk supplement--in a hospital for children. The cost of implementing this program is compared with the benefits of avoiding nosocomial rota virus infection. The results of the study suggest that, taking a range of realistic values for the most significant variables, the use of the supplement would be cost-effective.

Animals↗
PubMed1993

Evidence for involvement of oxygen free radicals in bile acid toxicity to isolated rat hepatocytes.

The mechanisms by which hydrophobic bile acids are toxic to the liver are unknown. To determine whether the generation of free radicals is involved in the hepatotoxicity of bile acids, freshly isolated rat hepatocytes were incubated with individual bile acids (100 to 200 mumol/L) for 4 hr. Hepatocyte viability (trypan blue exclusion) declined to 40% to 50% in incubations with taurochenodeoxycholic acid and taurolithocholic acid, whereas taurocholic acid and tauroursodeoxycholic acid were not toxic. Lipid peroxidation was significantly associated with the loss of cell viability. Preincubation with different antioxidants-D-alpha-tocopheryl succinate, D-alpha-tocopherol, diphenyl-p-phenylenediamine, superoxide dismutase, catalase, superoxide dismutase + catalase, deferoxamine or apotransferrin-protected against the loss of viability and inhibited lipid peroxidation in cells incubated with 200 mumol/L taurolithocholic acid. alpha-Tocopheryl succinate added after 90 min of incubation with taurolithocholic acid ameliorated further hepatocyte toxicity and lipid peroxidation. Incubation of hepatocytes with 500 mumol/L of taurochenodeoxycholic acid or taurolithocholic acid under a low oxygen tension (9% O2) similarly caused lipid peroxidation and cell injury that was reversed by preincubation with D-alpha-tocopherol. These data suggest that oxygen free radicals may be involved in the pathogenesis of bile acid hepatotoxicity.

Animals↗
PubMed1992

Does chronic fatigue syndrome predispose to non-Hodgkin's lymphoma?

Chronic fatigue syndrome, an illness that frequently is associated with abnormalities of cellular immunity, has been reported anecdotally to be associated with an increased incidence of lymphoid hyperplasia and malignancy. This report describes an initial analysis of population-based cancer incidence data in Nevada, focusing on the patterns of non-Hodgkin's lymphoma prior to and subsequent to well described, documented outbreaks of chronic fatigue syndrome during 1984-1986. In a study of time trends in four age groups, the observed time trends were consistent with the national trends reported in the Surveillance, Epidemiology, and End Results Program. No statistically significant increase attributable to the chronic fatigue syndrome outbreak was identified at the state level. Additional studies are in progress analyzing the data at the country level, reviewing patterns in other malignancies, and continuing to monitor the cancer patterns over subsequent years.

Adolescent↗
PubMed1992

Integration host factor facilitates repression of the put operon in Salmonella typhimurium.

Transcriptional regulation of the put operon is mediated by a unique mechanism involving autogenous regulation by the PutA protein, a membrane-associated dehydrogenase. The 420-bp put control region contains the putP and putA promoters, multiple operator sites, multiple catabolite repression protein binding sites, and several potential integration host factor (IHF)-binding sites (ihf). In this study, we show that IHF facilitates repression of the put operon in vivo, and IHF binds specifically to two ihf sites in the put control region in vitro. DNA gyrase mutants that alter the degree of chromosomal supercoiling do not affect put regulation, indicating that the effect of IHF on put expression is in this case independent of supercoiling.

Amino Acid Sequence↗
PubMed1992

Plasmid cloning vectors for the conjugal transfer of DNA from Escherichia coli to Streptomyces spp.

We have constructed cloning vectors for the conjugal transfer of DNA from Escherichia coli to Streptomyces spp. All vectors contain the 760-bp oriT fragment from the IncP plasmid, RK2. Transfer functions need to be supplied in trans by the E. coli donor strain. We have incorporated into these vectors selectable antibiotic-resistance markers (AmR, ThR, SpR) that function in Streptomyces spp. and other features that should allow for: (i) integration via homologous recombination between cloned DNA and the Streptomyces spp. chromosome, (ii) autonomous replication, or (iii) site-specific integration at the bacteriophage phi C31 attachment site. Shuttle cosmids for constructing genomic libraries and bacteriophage P1 cloning vector capable of accepting approx. 100-kb fragments are also described. A simple mating procedure has been developed for the conjugal transfer of these vectors from E. coli to Streptomyces spp. that involves plating of the donor strain and either germinated spores or mycelial fragments of the recipient strain. We have shown that several of these vectors can be introduced into Streptomyces fradiae, a strain that is notoriously difficult to transform by PEG-mediated protoplast transformation.

Bacteriophages↗
PubMed1992

Primary relationships affect the psychological health of homosexual men at risk for AIDS.

Less is known about the effects of primary relationships on psychological health for homosexual men and women than for heterosexual men and women. Given the HIV/AIDS epidemic, the primary relationships of homosexual men are especially important to examine at the present time. Using questionnaire data collected from 259 homosexual men, this study examined the effects of status and quality of relationship on psychological health. Analysis indicated that homosexual men who are in primary relationships experience fewer depressive symptoms and greater well-being than other homosexual men but that being in a relationship does not predict changes in these outcomes over time. Men who report high quality of relationship show improvements over time in psychological health. These findings are discussed in light of the HIV/AIDS epidemic.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Evaluation of latex allergy in patients with meningomyelocele.

Seventy-six patients with meningomyelocele were evaluated for latex sensitivity by medical history and epicutaneous skin testing. Four different latex glove extracts, two nonlatex glove extracts, cornstarch, selected inhalant antigens, and negative and positive controls were used for skin testing. Forty-nine patients (64.5%) were skin test positive to latex extracts (latex-positive group). Twenty-four patients (49%) of the latex-positive group and none of the latex-negative group had histories of immediate reactions to latex products (P less than .001). The latex-positive group had a higher mean number of surgical procedures, 12.67 +/- 11.27, compared with 6.89 +/- 6.55 (P less than .001) in the latex-negative group. Twenty-three of the latex-positive patients (47%) used latex products daily compared to seven patients (26%) in the latex-negative group (P = .073). Twenty latex-positive patients (41%) had atopy compared with five patients (19%) of the latex negative group (P = .041). There was no significant difference between the two groups in age, sex, daily catheterization, or positive skin tests to cornstarch. All 76 patients tested negative to the nonlatex glove extracts. Ten control subjects tested negative for all latex and nonlatex glove extracts.

Adolescent↗
PubMed1992

Impact of pharmaceutical company representatives on internal medicine residency programs. A survey of residency program directors.

To survey internal medicine residency program directors regarding interactions between their residents and pharmaceutical company (PC) representatives (PCRs) a questionnaire was sent to the directors of all Accreditation Council for Graduate Medical Education-approved internal medicine residency programs. The survey included 444 program directors, of whom 272 (61.16%) responded. The majority of program directors, 228 (83.8%), allowed PCRs to meet with residents during working hours and 241 (88.6%) permitted PC sponsorship of conferences. About half of the program directors were "moderately" or "very" concerned about the potential adverse effects of PC marketing on resident attitudes and prescribing practices. Seventy percent "agreed" or "strongly agreed" that the benefits of PC sponsorship outweigh the adverse effects and 41.5% believed that refusal to allow PCRs to meet with residents would jeopardize PC funding of other departmental activities. Most program directors reported that alternate funds for conferences were available if PC support was withdrawn. "Unethical" marketing activities were observed by 14.3% of program directors and 37.5% reported that residents had participated in PC-sponsored trips during the 3 years prior to the survey. At the time of this survey, only 35.3% of programs had developed formal policies regulating PCR activities and 25.7% provided residents with formal instruction on marketing issues. Knowledge of the current extent of PCR interactions with residents may be helpful to program directors in developing policies regulating PC-marketing activities.

Attitude of Health Personnel↗
PubMed1991

Mineral homeostasis in obesity: effects of euglycemic hyperinsulinemia.

We explored the effects of insulin on mineral homeostasis in five lean and six moderately obese nondiabetic premenopausal women. Serum and urine minerals were measured before and during the steady-state phase of a euglycemic insulin clamp. Each subject participated in two insulin clamp studies on separate days at insulin infusion rates of 10 and 40 mU/m2/min. Euglycemic hyperinsulinemia was associated with (1) a significant increase in urinary calcium excretion when expressed per minute with no change in total serum calcium; (2) a decrease in urine and serum phosphate; (3) a decrease in serum potassium with no change in urine potassium; and (4) no measurable effects on urine or serum sodium. At any given insulin level, the obese individuals excreted significantly more calcium, phosphate, and potassium per minute than lean controls. While insulin administration had no effect on serum parathyroid hormone (PTH) or vitamin D levels, baseline serum 1,25(OH)2D concentration was significantly higher and serum ultrafilterable calcium was significantly lower in obese subjects than in lean controls.

Adult↗
PubMed1991

Lipogenic potential of liver from morbidly obese patients with and without non-insulin-dependent diabetes.

Intra-abdominal liver biopsies were obtained during surgery from fasted obese patients with non-insulin-dependent diabetes mellitus (NIDDM), obese normoglycemic controls, and lean controls. Lipid synthesis was studied in freshly isolated hepatocytes and liver homogenates from the three groups of subjects. Incorporation of 3H2O into the lipids of hepatocytes was determined in the absence and presence of insulin (0.1 mumol/L). The activities of five enzymes involved in fatty acid synthesis, and the incorporation of 14C-glycerol-3-phosphate into lipids were determined in liver homogenates. Basal lipid synthesis by hepatocytes was not different in the three groups of patients. Insulin stimulated lipogenesis by 8% +/- 30% in the lean controls, 33% +/- 8% in the obese controls and 17% +/- 6% in the NIDDM patients. No significant differences in the activities of the five enzymes that are involved in de novo fatty acid synthesis among the three groups of patients were observed. Similarly, incorporation of 14C-glycerol-3-phosphate by liver homogenates, in the presence of saturating or submaximal concentrations of fatty acids, did not differ among the three groups. These results show that under the experimental conditions of this study, including the fasted state of the patients, the basal capacity of liver of NIDDM patients to synthesize fatty acids or glycerides is the same as that of liver from obese and lean controls. Thus, it is likely that an increase in fatty acid flux into a liver with normal lipogenic potential may contribute to the increased synthesis of triglycerides by the liver of these patients in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Regulation of proline utilization in Salmonella typhimurium: a membrane-associated dehydrogenase binds DNA in vitro.

The PutA protein is a membrane-associated enzyme that catalyzes the degradation of proline to glutamate. Genetic evidence suggests that in the absence of proline, the PutA protein also represses transcription of the putA and putP genes. To directly determine whether PutA protein binds to the put control region, we analyzed gel retardation of put control region DNA by purified PutA protein in vitro. The put control region is 420 bp. Purified PutA protein bound specifically to several nonoverlapping fragments of control region DNA, indicating the presence of multiple binding sites in the control region. Electrophoretic abnormalities and behavior of circularly permuted fragments of control region DNA indicate that it contains a region of intrinsically curved DNA. To determine whether the multiple binding sites or the DNA curvature are important in vivo, two types of deletions were constructed: (i) deletions that removed sequences predicted to contribute to DNA curvature as well as potential operator sites and (ii) deletions that removed only potential operator sites. Both types of deletions increased expression of the put genes but were still induced by proline, indicating that multiple cis elements are involved in repression. These data suggest a model for put repression that invokes the formation of a complex between PutA protein molecules bound at different sites in the control region, brought into proximity by a loop of curved DNA.

1-Pyrroline-5-Carboxylate Dehydrogenase↗