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Biomedical subjects

R Cooper

Publications and source records attributed to R Cooper.

At least 433 records · Page 24Linked to original sources
PubMedDate not supplied

Efficacy and safety of adefovir dipivoxil with antiretroviral therapy: a randomized controlled trial.

CONTEXT: Adefovir dipivoxil is a nucleotide analog that has demonstrated effective antiretroviral activity against human immunodeficiency virus (HIV) with once-daily administration. OBJECTIVE: To determine if adefovir confers antiretroviral or immunologic benefit when added to stable antiretroviral therapy. DESIGN: Multicenter, 24-week, randomized, double-blind, placebo-controlled study. Enrollment was conducted from June 3, 1996, through May 6, 1997. SETTING: Thirty-three US HIV treatment centers. PARTICIPANTS: Of 1171 patients screened, 442 patients infected with HIV receiving stable antiretroviral therapy for at least 8 weeks with plasma HIV RNA greater than 2500 copies/mL and CD4+ cell count above 0.20 x 10(9)/L were randomized. INTERVENTION: Patients were randomized to receive either a single 120-mg/d dose of adefovir dipivoxil (n = 219) or an indistinguishable placebo (n = 223). All patients received L-carnitine, 500 mg/d. Open-label adefovir was offered after 24 weeks and was continued until the end of the study. MAIN OUTCOME MEASURES: Changes in HIV RNA from baseline, based on area under the curve and CD4+ cell levels, adverse events, and effect of baseline genotypic resistance on response to adefovir. RESULTS: Patients assigned to adefovir demonstrated a 0.4-log10 decline from baseline in HIV RNA compared with no change in the placebo group (P<.001), which continued through 48 weeks. CD4+ cell counts did not change. During the initial 24 weeks, elevated hepatic enzyme levels (P<.001), gastrointestinal tract complaints (P<.001), and weight loss (P<.001) were associated with use of adefovir. Between 24 weeks and 48 weeks elevations in serum creatinine occurred in 60% of patients, usually returning to baseline after discontinuation of adefovir. Patients with lamivudine or lamivudine and zidovudine resistance mutations demonstrated anti-HIV effects with adefovir (P< or =.01 vs placebo group). CONCLUSIONS: This study suggests that once-daily adefovir therapy reduces HIV RNA and is active against isolates resistant to lamivudine or lamivudine and zidovudine. Nephrotoxicity occurred when treatment extended beyond 24 weeks but was reversible.

Adenine↗
PubMedDate not supplied

Peptidergic transmission in the brain. V. Systemic correlates of central activation.

Inhibition of the hippocampus by the medial amygdala is mediated by vasopressin-like peptide. Because vasopressin has action on the periphery as well as the brain, we conducted experiments to evaluate the relationship between possible peripheral actions and the central effects of the endogenous peptide. In the acutely anesthetized rat, peptide-mediated inhibition of the hippocampus is not associated with significant changes in heart rate, blood pressure or body temperature. Peripheral injections of peptide agonist fail to evoke the central inhibition, and peripheral injections of peptide antagonist fail to block the central inhibition. Stimulation of central nuclei that contain vasopressin or a similar peptide also fail to duplicate the effect of stimulating the amygdala. We conclude that the peptidergic transmission is independent of peripheral causes or correlates.

Amygdala↗
PubMedDate not supplied

Measuring renal function in patients with diabetes mellitus.

We estimated the glomerular filtration rate in 33 patients from our diabetic clinic using three methods: the creatinine clearance measured from a timed urine sample and a serum creatinine; the creatinine clearance calculated from the serum creatinine according to the formula of Cockcroft and Gault; and, the plasma clearance of ethylenediaminetetra-acetic acid (EDTA) labeled with 51Cr ([51Cr]EDTA). We repeated the measurements in seven subjects. The measured creatinine clearance was not reproducible. The other two methods were correlated, but not according to the formula y = x. The calculated creatinine clearance significantly underestimated the [51Cr]EDTA clearance particularly at higher [51Cr]EDTA clearance rates. [51Cr]EDTA clearance has been shown by others to parallel, but underestimate, inulin clearance, the optimal method of estimating glomerular filtration rate but difficult to perform in routine practice. Accurately measuring renal function in routine clinical practice is difficult, and this must be borne in mind when making clinical decisions based on current measurements.

Aged↗
PubMedDate not supplied

Methylpendolmycin, an indolactam from a Nocardiopsis sp.

Methylpendolmycin, a new indole alkaloid with an N-methylisoleucine moiety incorporated in the nine-membered indolactam ring, has been isolated from an actinomycete culture of Nocardiopsis. Methylpendolmycin exhibited inhibition of phorbol ester binding to protein kinase C. Its structure was assigned on the basis of spectroscopic data.

Actinomycetales↗
PubMedDate not supplied

Wheelchair racing efficiency.

PURPOSE: For individuals with disabilities exercise, such as wheelchair racing, can be an important modality for community reintegration, as well as health promotion. The purpose of this study was to examine selected parameters during racing wheelchair propulsion among a sample of elite wheelchair racers. It was hypothesized that blood lactate accumulation and wheeling economy (i.e. oxygen consumed per minute) would increase with speed and that gross mechanical efficiency would reach an optimum for each athlete. METHOD: Twelve elite wheelchair racers with paraplegia participated in this study. Nine of the subjects were males and three were females. Each subject used his or her personal wheelchair during the experiments. A computer monitored wheelchair dynamometer was used during all testing. The method used was essentially a discontinuous economy protocol. Mixed model analysis of variance (ANOVA) was used to compare blood lactate concentration, economy (minute oxygen consumption), and gross mechanical efficiency across the stages. RESULTS: The results of this study show that both economy and blood lactate concentration increase linearly with speed if resistance is held constant. The subjects in this study had gross mechanical efficiencies (gme) of about 18%, with the range going from 15.222.7%. The results indicate that at the higher speeds of propulsion, for example near race speeds, analysis of respiratory gases may not give a complete energy profile. CONCLUSION: While there is a good understanding of training methods to improve cardiovascular fitness for wheelchair racers, little is known about improving efficiency (e.g. technique, equipment), therefore methods need to be developed to determine efficiency while training or in race situations.

Adult↗
PubMedDate not supplied

Obesity modifies the relationship between ambulatory blood pressure and natriuresis in children.

BACKGROUND: The objective in the present study was to evaluate if obesity beginning in the first two decades of life influences the relationship between ambulatory blood pressure and urinary sodium excretion. DESIGN AND METHODS: Eighty-five obese and 88 non-obese children aged 3-19 years were included in the study. For each subject, a 24h ambulatory blood pressure monitoring and a complete urine collection were simultaneously performed according to the protocols designed. The averages of ambulatory blood pressure and of the urinary excretion rates for sodium, potassium and creatinine were calculated separately for 24-h, awake and sleep periods as defined by a mini-diary. RESULTS: Weight and sodium excretion are directly associated with systolic blood pressure; however, the relationship between blood pressure and sodium excretion seems to be modified in obese children as compared to controls. The interaction between sodium excretion and weight was negative indicating that the rate of change of systolic blood pressure by sodium unit is smaller for the obese than for the non-obese, even though at the same urinary sodium excretion level the obese children had higher ambulatory systolic blood pressure. CONCLUSIONS: Obesity during the first two decades of life seems to restrict sodium excretion, leading to higher blood pressure values. The capacity to excrete sodium seems to be heterogeneous, the lowest capacity being at the highest blood pressure values. Subsets of the obese, those with the lowest ability to excrete sodium, may be further protected by low sodium intake in order to prevent a rise in blood pressure.

Adolescent↗
PubMedDate not supplied

Endoscopic documentation of unintentional perforation of the dividing membrane during amnioreduction for twin-twin transfusion syndrome.

OBJECTIVE: The purpose of this report is to document endoscopically the occurrence of unintentional piercing of the dividing membrane in a monochorionic twin pregnancy with twin-twin transfusion syndrome (TTTS). MATERIALS AND METHODS: The dividing membrane was visualized endoscopically during laser therapy in a patient with TTTS who had previously undergone therapeutic amniocentesis. The donor twin had no visible bladder, but the amniotic fluid volume had normalized after amniocentesis. RESULTS: The suspected membrane perforation was identified endoscopically during laser surgery. Five areas of vascular communications were identified and photocoagulated. CONCLUSIONS: Sonographic evidence of normalization of the amniotic fluid volumes after therapeutic amniocentesis with persistent nonvisualization of the bladder of the donor twin should not be interpreted as a sign of improvement of TTTS, but rather as indirect evidence of unintentional perforation of the dividing membrane. This complication can be confirmed endoscopically.

Adult↗
PubMedDate not supplied

Variability in 24-hour urine sodium excretion in children.

How many 24-hour urine sodium measurements are adequate for characterizing a child's salt intake? Can overnight urine specimens accurately replace 24-hour collections for salt assessment? A sample of 73 6th-8th grade children was taken from two parochial schools in Chicago to investigate systematically these questions. Seven consecutive 24-hour-urine specimens were collected from each child. The estimated ratio of intra- to inter-individual variances was 1.94 for 24-hour-urine sodium. Based on this value, eight 24-hour specimens are necessary to limit to 10% the diminution of the estimated correlation coefficient between 24-hour-urine sodium and blood pressure. Six measurements are required to reduce to 0.01 the probability of misclassifying a child in tertile 1 versus tertile 3. The overnight specimens show a moderate consistency with the 24-hour collections in detecting children with high or low salt intake. For example 92% and 85% of children in the fifth quintile and the third tertile respectively of the true mean overnight sodium have their true mean 24-hour Na in the upper half of the distribution. These results suggest that in a large scale epidemiologic study, overnight specimens may be reasonable alternatives when 24-hour-urine sodium is practically very difficult to collect.

Adolescent↗
PubMedDate not supplied

A survey of patterns of nonpharmacologic care for hypertensive patients, including recommendations for their children.

To ascertain current approaches of physicians to nutritional-hygienic management of hypertensive patients and their children, a survey was done among a random sample of Chicago-area generalists, internists, and cardiologists. Thirteen items related to advice for patients; two for their children. Of 713 physicians holding M.D. degrees in the sample, 573 (80%) responded. For hypertensive patients, the great majority of physicians indicated that they advise weight loss, avoidance of salt use at table, no smoking, regular exercise, limitation of alcohol intake, and avoidance of stressful situations. Although 98% advised weight loss, a minority responded positively to reduction of carbohydrate and/or fat intake. Only 25% recommended limiting the salt use of children, and only 19% recommended taking the blood pressure of children of hypertensive patients. These data indicate that the majority of Chicago-area practitioners advocate nutritional-hygienic measures for their hypertensive patients. Only a minority, however, apparently advocate primary preventive approaches for the children of hypertensive patients.

Adult↗
PubMedDate not supplied

Abnormal red blood cell ion transport and hypertension. The People's Gas Company study.

A population-based survey of 134 white men, recruited from the Chicago People's Gas Company labor force, was carried out to examine the association between sodium-lithium (Na-Li) countertransport and hypertension. Of the 134 participants in this industry-sponsored periodic health examination, 64 were normotensive and 70 were either taking antihypertensive medications or had a systolic pressure greater than or equal to 140 or a diastolic pressure greater than or equal to 90 mm Hg. The hypertensives were older and more overweight. Countertransport was significantly higher in hypertensives than in normotensives. Among the three subgroups of hypertensives--untreated, borderline (140/90 to 160/95 mm Hg), untreated definite (over 160/95 mm Hg), and treated--an increase in countertransport was consistently observed, significant for the latter two groups. The relationship between countertransport and hypertension was independent of overweight, with countertransport being significantly related to both blood pressure and overweight. Altered ion transport may play an important role in the etiology and/or pathophysiology of hypertension.

Adult↗
PubMedDate not supplied

Effect of dietary sodium reduction on red blood cell sodium concentration and sodium-lithium countertransport.

A randomized, crossover trial was carried out on the effect of moderate sodium reduction on red-blood-cell sodium metabolism. The participants were healthy high school students (mean age = 16 years, n = 33). Changes in sodium-lithium countertransport and intracellular sodium concentration were evaluated 24 days after a decrease in dietary sodium from approximately 110 to 40 mEq per day. Dietary sodium restriction had no significant effect on either sodium-lithium countertransport or intracellular sodium concentration.

Adolescent↗
PubMedDate not supplied

Trends in mortality from cerebrovascular diseases in the United States, 1960 to 1975.

A long-term decline in death rates from cerebrovascular diseases in the United States accelerated in 1969, with a further increase in the rate of decline after 1972. This break in the pattern of the mortality curve for stroke was observed in all 4 major sex-color groups, and affected all age groups in which a significant number of stroke deaths occur. The decline for non-whites was relatively and absolutely greater than for the comparable white sex. If the 1960 rates had persisted in 1975, 87,600 more lives would have been lost to cerebrovascular diseases. Although there are no data documenting a declining prevalence of hypertension in the population, detection, treatment and control of hypertension have improved markedly over recent years. A concomitant decrease in the severity of epidemic respiratory infection may have contributed to the improvement in recorded death rates from stroke. Mortality from all major cardiovascular diseases has demonstrated a parallel downward trend. Continued emphasis on public health efforts to detect and treat hypertension and other known cardiovascular risk factors can be expected to result in further improvement in cardiovascular mortality.

Adult↗