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Biomedical subjects

R A Wolfe

Publications and source records attributed to R A Wolfe.

At least 127 records · Page 7Linked to original sources
PubMed1986

Analysis of cardiac symptoms preceding cardiac arrest.

Prodromal symptoms and cardiac history were examined in 227 patients with coronary artery disease who were successfully resuscitated after out-of-hospital cardiac arrest. Cardiac arrest was sudden--with either no symptoms or symptoms for less than 1 hour--in 71% of the patients. Nonsudden death--death occurring after more than 1 hour of symptoms--occurred in 29% of the patients. A history of cardiovascular disease was present in 85% of patients with sudden cardiac arrest and in 83% with nonsudden arrest. Cardiac arrest occurred without symptoms in 38% of the patients with sudden cardiac arrest and was the first expression of coronary artery disease in 4% of the entire study group. This study indicates that cardiac arrest usually occurs with symptoms and almost always in the setting of a history of cardiovascular disease.

Angina Pectoris↗
PubMed1986

Seasonality of preterm birth in the Collaborative Perinatal Project: demographic factors.

Marked circannual variation in the incidence of preterm birth, adjusted for the normal seasonal fertility rate, was observed in data from the Collaborative Perinatal Project collected at 12 urban university centers during 1959-1966 (p less than 10(-5). The variation in monthly preterm birth rates ranged from a trough of 64% in May to a peak of 144% in September. This is considerably greater seasonal variation than found in most previous studies, which used differing definitions of prematurity. The seasonal trend was present for maternal age groups 22-26 years (p less than 0.005) and greater than 26 years (p less than 0.005), for Bureau of the Census socioeconomic index 3.6-4.9 (p less than 10(-4) and greater than 4.9 (p less than 0.01), for those living in northern states (p less than 10(-4), for married gravidas (p less than 10(-6), for blacks (p less than 0.05) and whites (p less than 0.001), but not for those less than age 22, those with socioeconomic index less than 3.6, those living in southern states, and those not married. Thus, preterm birth was seasonal in the population studied, and the seasonal factor was more evident in demographic groups less predisposed to deliver preterm. These findings may have implications for the pathogenesis of a portion of premature deliveries, and should be considered in the design of studies related to the pathogenesis of preterm birth.

Adult↗
PubMed1985

The effect of bystander CPR on survival of out-of-hospital cardiac arrest victims.

The effect of bystander cardiopulmonary resuscitation (CPR) was studied in 2142 emergency medical service (EMS) cardiac arrest runs. When bystander CPR was administered to cardiac arrest victims, 22.9% of the victims survived until they were admitted to the hospital and 11.9% were discharged alive. In comparison, the statistics for cardiac arrest victims who did not receive bystander CPR were 14.6% and 4.7%, respectively (p less than 0.001). A critical factor in patient survival was the amount of time that elapsed before the EMS personnel arrived and administered CPR. Patients who received bystander CPR were more likely to have ventricular fibrillation when the EMS arrived. Other factors relating to patient survival were the location of the victim at the time of the cardiac arrest and the age of the victim. Understanding these factors is important in developing community strategies to treat patients with cardiac arrest out of hospital.

Adult↗
PubMed1985

Fluctuations in basal plasma levels of pancreatic polypeptide in monkeys and humans.

We reported that significant rapid oscillations occur in basal plasma levels of insulin, glucagon, and glucose in rhesus monkeys and humans. We searched for evidence for similar spontaneous fluctuations also in plasma levels of pancreatic polypeptide (PP). Mean +/- SE basal plasma levels of PP were 236 +/- 15 pg/ml in 11 monkeys, 64 +/- 12 in nine normal-weight human subjects, and 74 +/- 10 in nine obese human subjects. 1) PP levels fluctuated with periods of 6-26 min. The fluctuations in PP were less regular than and did not temporally correlate with the fluctuations in plasma levels of insulin, glucagon, or glucose (usual periods 8-12 min). 2) In human subjects the concentration but not the periodicity of PP was related to obesity. 3) Comparisons of simultaneously determined levels of PP in portal and central venous plasma of monkeys suggested that PP may be extracted to varying degrees by the liver, even under basal well-controlled conditions, and that neither the size of the PP portal-central gradient nor the period and amplitude of fluctuations was associated with PP concentration. We conclude that plasma PP levels fluctuate with such a large amplitude that these fluctuations must be considered in the interpretation of experimental results based on limited numbers of samples.

Adult↗
PubMed1985

Predictive survival models for resuscitated victims of out-of-hospital cardiac arrest with coronary heart disease.

Resuscitated victims of cardiac arrest with coronary heart disease represent a group of patients with an accelerated mortality rate. Among 227 such patients in our follow-up study, 20% had died at 1 year and 50% were dead in slightly over 3 years. Predictors of death were related to use of digitalis, elevated blood urea nitrogen, cerebral vascular accident, previous myocardial infarction, and age. In a subset of 103 patients in whom ambulatory electrocardiographic recordings were available within 3 months of the arrest event, the presence of complexity and high-frequency ventricular premature beats (VPBs) (greater than or equal to 25/hr) were added to the mortality predictors of digitalis and diuretic therapy and elevated blood urea nitrogen. An almost equal number of patients died suddenly and nonsuddenly. Predictors of sudden death were treatment with quinidine and paired VPBs. Occurrence of arrhythmias was an important addition to the previous mortality predictors related to left ventricular dysfunction.

Actuarial Analysis↗
PubMed1985

A semiparametric model for regression analysis of interval-censored failure time data.

Left-, right-, and interval-censored response time data arise in a variety of settings, including the analyses of data from laboratory animal carcinogenicity experiments, clinical trials, and longitudinal studies. For such incomplete data, the usual regression techniques such as the Cox (1972, Journal of the Royal Statistical Society, Series B 34, 187-220) proportional hazards model are inapplicable. In this paper, we present a method for regression analysis which accommodates interval-censored data. We present applications of this methodology to data sets from a study of breast cancer patients who were followed for cosmetic response to therapy, a small animal tumorigenicity study, and a clinical trial.

Animals↗
PubMed1985

Clinical profiles of hospital discharge rates in local communities.

Using comprehensive 1980 data for hospitalization of the 9 million citizens of Michigan's lower peninsula, the authors have previously demonstrated that the discharge rates of local communities differ by a range of 2 to 1. This article seeks to identify differences in the clinical profile of high-use compared to low-use communities. Population-based rates and percentages of total discharges were studied for major clinical activity groups, such as cardiovascular disease, frequent diagnoses, rarely occurring diagnoses, short- and long-stay diagnoses, certain surgical procedures, and major organ groups of the diagnostic classification system. Although high-use communities tend to admit proportionately fewer surgical cases and proportionately more nonsurgical cases, few other such patterns could be demonstrated.

Adolescent↗
PubMed1984

Isolation of proteins from crude mixtures with silica and silica-based adsorbents.

Silica and silica-based adsorbents have been used to isolate specific proteins from crude mixtures. Acid-activated Nugel silica and Nugel SP-Silica were used to extract human immune interferon from the conditioned medium of mixed lymphocyte cultures. Human interleukin-2 was extracted from the conditioned medium of Jurkat cells with LiChroprep RP-8. In each case, batch absorption was accomplished by gentle stirring in a microcarrier vessel. The adsorbate was collected by sedimentation, and either batch-eluted or packed into a column for gradient elution. A high degree of concentration and purification was achieved with a high recovery of biological activity.

Adsorption↗
PubMed1984

Effects of leisure counseling on adult psychiatric outpatients.

This study evaluates the impact of a leisure counseling program on the leisure attitude and self-esteem of adult psychiatric outpatients. Sixteen outpatients at a private psychiatric hospital were assigned to one of two groups. Both groups received traditional outpatient services and programs. The experimental group also received a leisure counseling program that was offered for 10 consecutive weeks. Comparing the adult psychiatric outpatients' group scores to normative data revealed that their leisure attitude and self-esteem were unusual. Over the course of the intervention program, the experimental group relative to the control group experienced no significant change in their leisure attitude and self-esteem. The intervention program did emerge as differentially affecting members of the experimental group depending on their age. A discussion clarifies how leisure counseling and evaluation procedures could be made more appropriate for a psychiatric outpatient population.

Adult↗
PubMed1983

Mortality differences and speed of wound closure among specialized burn care facilities.

Burn patient mortality rates at 11 major American burn care units were investigated and were found to differ substantially after carefully adjusting for patient mix at each participating burn facility. The adjusted mortality rates differed by as much as a factor of two. Institution speed of full-thickness burn wound closure was found to be significantly associated with mortality experience, with lower mortality associated with quicker wound closure. The data analyzed were from the National Burn Information Exchange (12,000 cases).

Adolescent↗
PubMed1983

Two new burn severity indices.

Two new severity indices for burned patients based on the combined experience of 11,200 patients in 12 major U.S. burn centers are presented. Each index estimates the risk of death utilizing the patient's age, sex, size of burn, perineum involvement, and time from burn to admission, and is suitable for use with patients admitted within 2 weeks of the burn. The two indices differ in the specificity of the burn size information used. The first index utilizes only the per cent of total body surface burned. The second index, in addition, uses the amount of full-thickness burn. The more detailed index provides a somewhat more accurate estimate and may be used if an adequate estimate of the area of full-thickness burn is available. Applications include patient prognosis estimation and retrospective evaluation of new treatments. Methods for the computation and use of both indices are described together with illustrative examples.

Age Factors↗
PubMed1983

The effects of burn severity and institutional differences on the costs of care.

Burn care treatment is among the costliest yet least studied forms of care. This paper presents estimates of the magnitude and components of burn care costs. It analyzes the extent to which burn care cost is determined by severity of burns or by characteristics of the institution in which the patient is treated, based on patient-specific data from eight hospitals representing different levels of technical sophistication in the delivery of burn care. Costs of care are higher in specialized facilities. Many patients with small burns are treated in specialized facilities, at much higher costs than patients treated in general care facilities. Among specialized facilities, patient severity accounts for a portion of the variance in costs, but significant cost differences remain after adjusting for severity. These results suggest that cost-control efforts should concentrate on specifying criteria for admission to specialized burn facilities, regional coordination of facilities and institutions, and improved facilities design and management.

Burn Units↗
PubMed1982

Prognostic factors in nasopharyngeal malignancy.

Data collected from review of 99 patients with carcinoma of the nasopharynx was submitted for statistical analysis. The purpose of the analysis was to determine patient, tumor and treatment factors that influence survival. The only patient factor observed to influence survival was patient age (P = 0.05). Greatest survival was noted for patients in the age group 0 to 20 years (44%), while poorest survival rates were in patients over 60 years of age (14%). Tumor factors influencing survival included the location of regional metastases (P = 0.05). Homolateral cervical metastases was associated with survival rates approximating 30% compared with 10% when bilateral metastases were present. Survival decreased markedly as cervical metastases progressed from the upper third of the neck to involvement of the middle and lower thirds. Survival was 20% when nodal involvement was confined to the upper neck compared with 8% when metastases extended to lower cervical regions. The only treatment factor apparently influencing survival was duration of therapy (P = 0.08). Longer treatment periods offered better five-year control rates. Higher dosage levels of radiotherapy were associated with improved survival, but not significantly so.

Adolescent↗
PubMed1982

Rapid fluctuations in plasma catecholamines in monkeys under undisturbed conditions.

We have demonstrated in monkeys and in man sustained synchronous oscillations in plasma levels of insulin, C-peptide, glucagon, and glucose that have periods ranging from 8 to 11 min. To identify the mechanisms of these oscillations, we studied plasma levels of catecholamines in search for periodic fluctuations. Blood was obtained at 2-min intervals from fasting, undisturbed, chair-adapted male rhesus monkeys via chronically implanted central venous catheters. Plasma levels of epinephrine, norepinephrine, and dopamine were measured by a radioenzymatic assay. Large fluctuations in plasma epinephrine were observed with an average peak-to-trough amplitude of 34 pg/ml at a mean level of 122 pg/ml. Similar fluctuations in norepinephrine and dopamine occurred and were correlated to those of epinephrine: r = 0.51 and 0.35, respectively. The most common periodicity in all three catecholamines was 6-13 min/cycle as determined by spectral analyses. Cross-correlation analyses indicated that fluctuations in the catecholamines were significantly negatively correlated with oscillations in insulin and were unrelated to fluctuations in glucagon. These fluctuations in plasma catecholamines may be related to mechanisms controlling the periodicity observed in plasma insulin and glucose.

Animals↗
PubMed1982

Influence of nutritional state on periodicity in plasma insulin levels in monkeys.

Rapid sustained oscillations in basal plasma levels of insulin, glucose, and glucagon (9-12 min/cycle) have been identified in rhesus monkeys and in humans. To assess the possible regulatory role of nutritional state in the control of these plasma fluctuations, 12 chronically cannulated conscious rhesus monkeys were studied at varying intervals following ingestion of a mixed meal. Blood samples were withdrawn at 2-min intervals for periods of 10-30 min. In the postprandial period both absolute and relative amplitudes (half amplitude percent) of oscillations increased up to 16 h postfeeding to maximal amplitudes of +/- 32% for insulin, +/- 4% for glucose, and +/- 22% for glucagon. Periods were consistently in the 9- to 12-min range for insulin and glucose. Progressive deprivation to 88 h produced decreases in amplitudes and more irregularity in fluctuations but did not affect the underlying periodicity of these oscillations in plasma levels of insulin, glucose, and glucagon. Results are consistent with the existence of one or more inherent oscillators in the pancreas that act to synchronize the release of hormones from particular types of islet cells. The amplitude of these oscillations but not the frequencies is associated with changes in liver metabolism and nutritional state.

Animals↗
PubMed1982

Rapid oscillations in plasma insulin, glucagon, and glucose in obese and normal weight humans.

We have previously identified in fasting monkeys large amplitude, rapid oscillations in plasma levels of insulin, glucagon, and glucose. To determine whether such spontaneous oscillations also occur in man, we studied 9 healthy normal weight subjects and 11 obese volunteers (145-316% ideal body weight). During the morning hours after a 16-h fast, peripheral venous blood was withdrawn at precise 1- or 2-min intervals over 40-120 min. Spectral analysis of the assay results showed significant oscillations in plasma levels of insulin and glucose, with periods ranging from 8-16 min (P less than 0.05). In this range, the means of the oscillatory periods in normal weight subjects were 12.1 +/- 1.0 min for insulin and 11.2 +/- 0.8 min for glucose. The oscillatory periods on obese subjects were not different from those in normal weight subjects (12.4 +/- 0.7 min for insulin and 12.1 +/- 0.9 min for glucose). Periodicity in plasma levels of glucagon was observed in the range of 12-23 min. Based on cross-correlation analysis, the periodic fluctuations in insulin, glucose, and glucagon showed no consistent relationships; the patterns observed did not support the presence of feedback loops among these parameters as the mechanism of these spontaneous fluctuations. Our data indicate that basal plasma levels of insulin, glucagon, and glucose fluctuate rapidly in man. The physiological function of these oscillations is yet to be identified; they may play a role in the regulation of responsiveness of the respective target tissues or of their own release into the circulation.

Adult↗
PubMed1981

Distinctive effects of hydrocortisone on the modulation of EGF binding and cell growth in HeLa cells grown in defined medium.

Hydrocortisone modulates the binding capacity of HeLa cells for 125I-labeled epidermal growth factor (EGF). A twofold increase in 125I-labeled EGF binding is observed within 24 hours after the addition of pharmacological concentration of hydrocortisone (5 X 10(-8) - 1 X 10(-6) M). This enhancement of binding is reversible, and occurs when the cells are cultured in either serum-supplemented or completely defined, serum-free, hormone-supplemented medium. Scatchard analysis of the binding data indicates that the number of 125I-EGF binding sites is increased, and that no appreciable change in the affinity of the EGF receptor for labeled EGF occurs. In the serum-free condition hydrocortisone stimulates the growth of HeLa cells, but we have observed no connection between this growth stimulation and the enhancement of EGF binding. The growth response to hydrocortisone is independent of EGF, and the concentration dependency of the growth response to EGF is unaltered by the addition of hydrocortisone to the medium. Hydrocortisone elicits the growth response at a concentration as low as 5 X 10(-9) M, while a concentration higher than 5 X 10(-6) M is required to affect the binding capacity for 125-EGF. These effects are specific for glucocorticoid steroids. Similar concentrations of progesterone, testosterone, or estradiol produce no measurable response. Although the elevation of EGF receptor levels in the serum-supplemented medium is similar to that observed in the serum-free cultures, hydrocortisone is growth-inhibitory under these conditions. This growth inhibition occurs at pharmacological concentrations of hydrocortisone with a concentration dependency that is similar to that of the EGF receptor modulation.

Blood↗