Search PubMed⌕ Search

Biomedical subjects

R Cooper

Publications and source records attributed to R Cooper.

At least 217 records · Page 12Linked to original sources
PubMed1990

Slowdown in the decline of stroke mortality in the United States, 1978-1986.

The gradual decline in stroke mortality rates observed in the United States since 1900 accelerated markedly around 1973 for whites and around 1968 for blacks. During the next decade stroke mortality rates decreased by almost 50% so that the United States now experiences one of the lowest stroke mortality rates in the world. Beginning in 1979, however the annual rate of decline in stroke mortality began to slow considerably. Comparing the period 1979-1986 with the previous decade, a 57% slowing in the absolute rate of decline (as estimated by the slope of the linear portion of the mortality curve) was observed for white men; the corresponding slowdowns in the rate of decline were 58% for white women, 44% for black men, and 62% for black women. If the decline during the 1980s had continued at the rate observed for the period 1968/73-1978, there would have been 131,000 fewer stroke deaths during the period 1979-1986, 28,000 fewer in 1986 alone. This slowdown in the rate of decline in stroke mortality is occurring while mortality rates for both coronary heart disease and all causes are leveling off. The reasons for this change in the mortality trend remain unknown, and corresponding trends in the treatment and control of hypertension do not provide an entirely satisfactory explanation.

Age Factors↗
PubMed1990

Labetalol in the control of cardiovascular responses to electroconvulsive therapy in high-risk depressed medical patients.

Labetalol, a drug with alpha- and beta-adrenergic receptor blocking effects, was used to attenuate hypertension and tachycardia associated with electroconvulsive therapy (ECT) in a series of 11 elderly patients with refractory depression and cardiovascular disease in a placebo-controlled, double-blind crossover study design. As compared with placebo, labetalol was found to blunt mean arterial pressure (MAP) increase by up to 8.26% (p less than .001), heart rate increased by up to 26.07% (p less than .001), frequency of atrial arrhythmias by up to 100% (p less than .01), and premature ventricular contractions by 41.97%. No untoward side effects were observed, and no effect on treatment outcome was noted. Labetalol appears to be an effective and safe agent to use in decreasing hypertension, tachycardia, and possibly arrhythmias in high-risk medical patients with cardiovascular disease undergoing ECT.

Aged↗
PubMed1990

Trends in hospitalization rates for heart failure in the United States, 1973-1986. Evidence for increasing population prevalence.

Discharge data from a representative sample of short-stay US hospitals were examined to obtain information regarding trends in the prevalence of congestive heart failure from 1973 through 1986. During this 14-year period, the number of discharges more than doubled and the age-adjusted rates increased from 53% to 88% among the four major sex-race groups. On average, nonwhite men experienced annual hospitalization rates 33% higher than white men, while for women the corresponding nonwhite rates were 50% higher. Hospitalization rates during this period remained constant for persons younger than 55 years but rose sharply in the elderly. Concurrently, a slight decline in case fatality rates for an individual hospitalization was seen. The two factors accounting for the growing prevalence of congestive heart failure seem to be the increasing average age of the population and the longer survival of persons with chronic heart disease. The role of improved medical therapy during the period of this study remains uncertain. Increasing demands to provide care for the congestive heart failure syndrome are likely to continue in the coming years, and medical facilities should develop new intervention strategies to treat or prevent the underlying conditions leading to heart failure as well as decrease the need for hospitalization in this common disorder.

Adult↗
PubMed1989

Severity of coronary artery disease among blacks with acute myocardial infarction.

A growing body of evidence suggests that survival after acute myocardial infarction (AMI) is considerably worse among blacks than whites. The severity of coronary artery disease (CAD), as measured by the number of diseased vessels and the degree of left ventricular dysfunction, is the major determinant of survival after AMI. To determine whether or not the severity of CAD could explain the poor prognosis in a cohort of blacks followed at this institution, cardiac catheterization was performed in a consecutive series of 51 patients less than 70 years of age. All patients were studied within 2 weeks after AMI. The mean age of the patients was 56 +/- 8 (mean +/- standard deviation) and 71% were men. A greater than or equal to 50 narrowing in 0, 1, 2 or 3 coronary arteries was noted in 5, 24, 40 and 31%, respectively. Left main stenosis was present in 3 patients (6%) and the mean left ventricular ejection fraction was 55%. In a subgroup of 20 patients echocardiographic estimates of left ventricular mass/height yielded a mean of 196 g/m, and left ventricular hypertrophy on echocardiogram was present in 74%. These data indicate that among blacks with AMI in this series CAD was only modestly more severe than expected and suggest that other factors most likely explain the high mortality in blacks after hospital discharge.

Black or African American↗
PubMed1989

Microtubule depolymerization inhibits the regulation of alpha 1-acid glycoprotein mRNA by hepatocyte stimulating factor.

Hepatocyte stimulating factor (HSF, a polypeptide cytokine) is a major regulatory hormone responsible for hepatic acute-phase reactant (APR) induction following acute systemic injury. The mechanisms by which HSF regulates APR synthesis in the liver are unknown. Microtubules are involved in a number of polypeptide hormone-mediated events which can be modified, either positively or negatively, by microtubule depolymerizing agents. In this study we have used colchicine (a microtubule depolymerizing drug) to assess whether or not HSF-mediated changes in rat hepatic alpha 1-acid glycoprotein (AGP) or albumin mRNA levels require an intact microtubule cytoskeletal system. Cultured rat hepatocytes were pretreated for 30 min with either colchicine (10(-6) M), or the inactive isomer lumicolchicine (10(-6) M), or fresh medium. Following pretreatment, purified murine macrophage HSF (10 units/ml) was added and the cells were incubated for an additional 12 h. Colchicine, but not lumicolchicine, significantly inhibited the HSF-dependent regulation of mRNA for the positive APR, AGP, but had no effect on the mRNA levels of albumin, a negative APR. Furthermore, removal of colchicine from previously inhibited cultures allowed HSF to restimulate AGP mRNA expression. These data suggest that microtubules may play a regulatory role in controlling the expression of the genes for positive acute-phase proteins and may explain the temporal differences found in vivo between positive and negative APR expression.

Animals↗
PubMed1989

Pulmonary function in preterm infants following treatment with intravenous indomethacin.

Pulmonary function tests, including measurements of arterial blood gas levels, total pulmonary compliance, and arterial-alveolar oxygen ratios, were performed in 38 ventilator-dependent preterm infants with respiratory distress syndrome who weighed less than 1500 g at birth. Twenty-seven had a physiologically significant patent ductus arteriosus (PDA). Twelve were assigned at random to receive three doses of intravenous indomethacin, 0.2 mg/kg per dose, on the fourth day of life. This treatment resulted in ductal closure in seven infants by the seventh day of life. Another concurrently observed group of 15 infants with PDA received no indomethacin. A third group of 11 infants lacked evidence of a PDA. Pulmonary function in the infants who received indomethacin did not differ significantly from that in the other two groups.

Ductus Arteriosus, Patent↗
PubMed1989

Lack of effects from 2000-Hz magnetic fields on mammary adenocarcinoma and reproductive hormones in rats.

Female rats were implanted with mammary adenocarcinoma tissue and 25 days later exposed to 2,000-Hz magnetic fields 1 h a day for 9 days. Analysis showed that tumor weights and the levels of several reproductive hormones were not significantly different between treated and control animals. Other studies with a similar design have also reported no significant effects from magnetic field exposure. However, vaginal smear data from all animals revealed that handling and restraint stress may have confounded the detection of subtle magnetic field effects.

Adenocarcinoma↗
PubMed1989

Hypertension as a cause of lower than expected death rates from coronary artery disease among blacks.

Coronary risk factors are more prevalent among blacks than whites in the United States. It is therefore paradoxical that age-adjusted death rates for coronary artery disease (CAD) are similar in the two racial groups. The major risk factor for CAD that is more common among blacks than whites is hypertension, which increases the risk of CAD by two- to fourfold, depending on the presence of smoking, hypercholesterolemia, or other factors. Two general hypotheses have been advanced to explain the lower than expected CAD rates among blacks: (1) the presence of some protective factors, such as increased levels of high density lipoprotein cholesterol (HDL); or (2) selective loss of CAD-prone black individuals due to other causes of mortality. Analysis of age-specific death rates from the vital statistics records strongly suggests that differential survival in the black and white populations, i.e., mortality selection, is the primary explanation of this phenomenon. We sought to test this hypothesis by examining an entirely independent data base. Data from the National Hospital Discharge Survey for the years 1973-1984 were evaluated to determine whether there were age-related differences in case-fatality rates between whites and blacks, and whether a crossover pattern in mortality could be discerned. The results demonstrate that in-hospital case-fatality rates for acute myocardial infarction (MI) were 10% to 70% higher for each of the 10-year age groups for blacks up to age 70 years, at which time a crossover occurred. The median age at which death due to MI occurred in blacks was approximately 5 years earlier than in whites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Noninvasive diagnosis of congenital left coronary artery to right ventricle fistula by nuclear magnetic resonance imaging.

In two children with left coronary artery to right ventricle fistula, nuclear magnetic resonance imaging provided high-quality images of the course of the dilated coronary artery and its termination in the right ventricular apex. The advantages of this noninvasive multiplanar imaging technique for visualization of coronary fistulae and dilated coronary arteries are described. This report represents the first description of coronary artery fistula by nuclear magnetic resonance imaging.

Adolescent↗
PubMed1989

Slow potential changes related to the velocity of target movement in a tracking task.

During an 18 sec smooth pursuit tracking task slow waves in the EEG were found to be correlated with the absolute velocity of the target. They were maximum at the vertex. These are thought to be concerned with the prediction of the future position of a target in some cerebral feed-forward system in which both input information and output motor action are integral parts and illustrate sensorimotor integration in man.

Adult↗
PubMed1989

Increased peripheral lymphocytes, lymphoid hepatitis and anaemia in African vervet monkeys seropositive to retroviruses.

Wild-caught African Vervet monkeys are commonly infected by Simian T-lymphotropic virus I (STLV1) and Simian immunodeficiency virus (SIV), yet the natural histories of these infections are largely unknown. Seropositivity was associated with increased total, T and atypical lymphocytes. In seropositive females there was mild, normocytic, normochromic anaemia. Lymphoid hepatitis was present in seven seropositive cases. African Vervets used in biomedical research, vaccine production and organ transplantation research are often infected by exogenous retroviruses which can be oncogenic and immunosuppressive in captive monkeys. Elimination of these infections may be possible by breeding Vervets in captivity.

Anemia↗
PubMed1989

Chronic exposure to carbon monoxide at high altitude: effects on mean electrical axis.

The effects of breathing CO continuously at high altitude on the mean electrical axis of the heart, hematocrit ratio and body weight were studied in laboratory rats. Laboratory rats were exposed for 6 weeks to: 100 or 500 ppm CO; 15,000 feet stimulated high altitude (SHA); or 100 or 500 ppm CO at SHA. SHA decreased body weight significantly; CO and CO-SHA interaction had no significant effect on body weight. CO and SHA increased hematocrit ratio significantly; five hundred ppm CO increased hematocrit ratio to a greater extent than 100 ppm CO. There was a significant interaction between 500 ppm CO and SHA on hematocrit ratio. The mean electrical axis (MEA) was shifted to the right by SHA, and shifted to the left by CO. The effect was dose dependent, with the greater left shift occurring with 500 ppm CO. There was a significant interaction between 500 ppm CO and SHA on the MEA. These results indicate that, in general, the effects produced by 15,000 feet SHA are not intensified by 100 ppm CO, but are intensified by 500 ppm CO.

Altitude Sickness↗
PubMed1989

A dose-response analysis of methoxychlor-induced alterations of reproductive development and function in the rat.

In the present study rats were dosed from weaning, through puberty and gestation, to Day 15 of lactation with methoxychlor at 25, 50, 100, or 200 mg/kg/day. Morphological landmarks of puberty were measured, including the ages at vaginal opening, first estrus, and first estrous cycle in females and at preputial separation in males. In the female, estrous cyclicity, fertility, litter size, number of implantation sites, organ weights, and ovarian and uterine histology were also measured. The viability of the offspring (F1) and their fertility were evaluated using a continuous breeding protocol. Males were necropsied after breeding, the reproductive organs were weighed, and the cauda epididymal sperm counts were determined. One testis was used for histopathology, while the other was used to quantify interstitial fluid (IF) content, IF testosterone concentration, and testicular sperm production. Testosterone and androgen-binding protein were measured in the caput epididymis, and sperm motility and morphology were evaluated from a caudal sample. The serum and pituitary were saved for hormonal determinations. Methoxychlor accelerated the age at vaginal opening and first estrus, and the vaginal smears were cornified. Growth was retarded at 100 and 200 mg/kg/day and fertility was reduced when the females were bred with untreated or similarly treated males. In the highest-dose group, the mated females went from constant estrus into pseudopregnancy following mating, but they had no implants. In males, methoxychlor treatment markedly reduced growth, seminal vesicle weight, cauda epididymal weight, caudal sperm content, and pituitary weight. Puberty was delayed in the two highest-dosage groups. Testicular sperm measures were much less affected than caudal measures. Testis weight and histology were slightly affected, and testicular sperm production, sperm morphology, and motility were unaffected. Endocrine function of the testes and pituitary was altered by methoxychlor administration. Leydig cell testosterone production, in response to human chorionic gonadotropin challenge, was reduced and pituitary levels of prolactin, thyroid-stimulating hormone (TSH), and follicle-stimulating hormone (FSH) were altered. In contrast, serum levels of prolactin, FSH, and luteinizing hormone were unaffected. Serum TSH was reduced by 50% of control at 100 and 200 mg/kg/day, while pituitary levels were increased. Gonadotropin-releasing hormone concentration in the mediobasal hypothalamus was also elevated. In spite of the many reproductive alterations, the fertility of treated males was not reduced when they were mated with untreated females.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Incidence and perception of psychosocial stress: the relationship with breast cancer.

This study explored the incidence and perception of psychosocial stress among 1596 patients attending breast screening clinics and 567 controls attending a well women clinic. It was found that some major life events (e.g. death of husband, death of close friend) were significantly related to breast disease and severity. The implications of the results are discussed.

Adaptation, Psychological↗