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R A Wolfe

Publications and source records attributed to R A Wolfe.

137 records · Page 8Linked to original sources
PubMed1981

Selective cell culture of brain cells by serum-free, hormone-supplemented media: a comparative morphological study.

We cultured single cell suspensions derived from enzymatically digested rat and mouse brains in the serum-free, hormone-supplemented media originally established for culturing glioma (C6) and neuroblastoma cell lines (B104). We succeeded in selecting different cell types by varying the hormones added to the culture medium. In addition to the medium the attachment factors used for coating the culture dishes proved important for the establishment of a selective culture system. In a comparative morphological study we show that different particular microenvironmental conditions determine the growth and/or survival of different cell types of dissociated brain cells.

Animals↗
PubMed1981

Neural influences on oscillations in basal plasma levels of insulin in monkeys.

The effects of cholinergic and adrenergic blocking agents on the period and amplitude of sustained oscillations in plasma levels of insulin and glucose were studied in 16 overnight-fasted conscious rhesus monkeys. Blood samples were withdrawn at 2-min intervals before and during or following administration of drugs that affect neurotransmission. Cholinergic blockade with atropine had no effect on the oscillations. alpha-Adrenergic blockade with phentolamine caused a rise in plasma insulin that lasted less than 10 min and was followed by a slight, although not consistent, decrease in mean insulin and a consistent small decrease in glucose. There was a sustained increase in heart rate, but no effect on the oscillations of insulin or glucose. beta-Adrenergic blockade induced by propranolol led to persistent decreases in mean plasma insulin 60% below the base line, small but variable decreases in glucose, and a sustained decrease in heart rate, but no change in period or relative amplitude of the oscillations in plasma levels of either insulin or glucose. General anesthesia with pentobarbital did not eliminate these oscillations. Our observations on the failure of the blockade of certain putative efferent pathways or depression of higher cortical centers to alter the period of the oscillations of insulin reduce the likelihood that the oscillations are transmitted from a pacemaker in the central nervous system.

Animals↗
PubMed1981

Monotonic dichotomous regression estimates: a burn care example.

Methods for estimating a dichotomous response regression function are discussed. A smoothed nonparametric monotonic estimator is developed and a procedure for estimating its variance is given. In an institutional differences study, the probability of death from a burn injury is related to the severity of the burn injury for patients treated at several specialized burn care units.

Burns↗
PubMed1980

Epidermal growth factor-induced down-regulation of receptor does not occur in HeLa cells grown in defined medium.

125I-Labeled epidermal growth factor (EGF) binds to HeLa cells in culture under completely defined conditions in a specific and saturable manner. When the cultures are maintained in serum, all the reported phenomena of down-regulation occur. In contrast, in cultures maintained in serum-free hormone-supplemented medium, binding is maximal after 50 min and remains constant for at least 18 hr. EGF retains its mitogenic activity in this defined system; as little as 4 pM EGF elicits a 2-fold increase in cell number in 5 days. EGF appears to be in reversible equilibrium with a constant number of surface receptors, and gel filtration analysis indicates a decrease in the rate of degradation and release of bound 125I-labeled EGF. These results indicate that EGF can retain its mitogenic activity in the absence of concomitant down-regulation.

Cell Division↗
PubMed1980

Continuous culture of rat C6 glioma in serum-free medium.

In this communication we describe serum-free culture conditions for the serial propagation of the C6 glioma cell line. The growth rate, saturation density, and morphology of these cells are equivalent to those of their serum-grown counterparts when cultured in a 3:1 mixture of Dulbecco's modified Eagle's medium and Ham's medium F-12 supplemented with trace elements, insulin, transferrin, fibroblast growth factor, linoleic acid complexed to fatty acid-free bovine serum albumin, and a serum-spreading factor (SSF) partially purified from human plasma. The requirement for SSF in the medium can be satisfied by preincubating the tissue culture dishes with SSF. Tissue culture dishes sequentially pretreated with poly-D-lysine and purified cold insouluble globulin will also substitute for this requirement. The fatty acid-free bovine serum albumin/linoleic acid complex increases the growth rate of these cells but has no appreciable effect on their morphology, saturation density, or ability to grow with repeated subculture. The growth stimulation caused by this complex appears to be dependent on the fatty acid, as the fatty acid-free bovine serum albumin alone has no effect on the growth rate. Linoleic acid is cytotoxic in the absence of bovine serum albumin, and the fatty acid-free bovine serum albumin prevents this toxicity. Other fatty acids including oleic, arachidonic, and palmitic only partially substitute for the growth-promoting effect of linoleic acid.

Animals↗
PubMed1979

Para-aminobenzoate inhibition of precipitation of urine salts.

Lehmann's observation that potassium para-aminobenzoate has a "salt precipitating preventive effect" in urine was confirmed in rats. This effect persisted during the 3-week period of drug administration. There was associated no significant change in urine volume, osmolality, or per cent solids. Since there is a large clinical experience in the chronic use of even larger doses, it would appear quite feasible to determine the clinical usefulness of this property of para-aminobenzoate in the prevention of recurrent renal calculi.

4-Aminobenzoic Acid↗
PubMedDate not supplied

Income and survival in chronic dialysis patients.

The relationship between income and survival rates for chronic dialysis patients in Michigan was examined. To evaluate the relative risk (RR) of dying, by income, a Cox survival regression model was used to adjust for age, race (black versus white), gender, dialytic treatment modality, year of first end-stage renal disease (ESRD) therapy, and primary cause of ESRD. The average household income reported from census data for the ZIP Code of residence for each patient was analyzed as a socioeconomic indicator. Treatment modality on day 120 of ESRD was classified as either center hemodialysis (HD) or CAPD. All new patients, aged 20-59 and registered at the Michigan Kidney Registry between 1/1/80 and 12/31/87 were included in the study. Patients were followed from day 180 of ESRD until death, censoring at transplant, or 12/31/87. The adjusted relative risk of dying decreased for black patients by 3.3% per $1,000 increase in income (p less than 0.01), while the trend by income for white patients was negligible (p greater than 0.10). The difference in trends for the two groups was statistically significant (p less than 0.01). This is a surprising result, since white patients have higher death rates, overall, than do black patients, particularly among subgroups with diabetes and hypertension whose RR was 1.77 and 1.82, respectively. Poor socioeconomic status of the area of residence has a strongly negative effect on survival for black patients, but not for white patients. The reasons for the relationship of death rates with income, especially for black patients, need to be examined in greater detail.

Adult↗
PubMedDate not supplied

The study of outcomes for CAPD versus hemodialysis patients.

OBJECTIVE: To discuss potential reasons for reported differences in the results of several recent studies comparing mortality risk among continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis patients, and to assess the role of statistical methods and study design. DATA SOURCES: Recent published reports comparing mortality risk among patients treated with CAPD and hemodialysis. CONCLUSIONS: Differences in study design, study populations, sample size, data collection, and availability of data likely account in part for the differences in available study results. The Cox model is a valuable tool, particularly for observational studies. Observed outcome differences for CAPD and hemodialysis patients may be due to either the dialytic modality itself or other factors such as differences in patient selection, practice patterns, dialysis dose, patient compliance, etc. Relative mortality rates for hemodialysis and CAPD patients may vary by country, as these factors may differ internationally. A randomized clinical trial is necessary to best determine the effect of the modality itself.

Humans↗