Search PubMed⌕ Search

Biomedical subjects

E Rogers

Publications and source records attributed to E Rogers.

At least 55 records · Page 3Linked to original sources
PubMed1992

Artificial blood substitutes.

Investigations directed toward the development of an effective artificial blood substitute are continuing as concerns remain regarding the safety and adequacy of the nation's blood supply. Perfluorochemical compounds, modified hemoglobin solutions, and microencapsulated hemoglobin represent the major areas of research. If a successful red cell substitute can be developed, many problems inherent in current blood transfusion practices could be alleviated, particularly in emergency situations.

Blood Substitutes↗
PubMed1991

Unassisted refolding of urea unfolded rhodanese.

In vitro refolding after urea unfolding of the enzyme rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) normally requires the assistance of detergents or chaperonin proteins. No efficient, unassisted, reversible unfolding/folding transition has been demonstrated to date. The detergents or the chaperonin proteins have been proposed to stabilize folding intermediates that kinetically limit folding by aggregating. Based on this hypothesis, we have investigated a number of experimental conditions and have developed a protocol for refolding, without assistants, that gives evidence of a reversible unfolding transition and leads to greater than 80% recovery of native enzyme. In addition to low protein concentration (10 micrograms/ml), low temperatures are required to maximize refolding. Otherwise optimal conditions give less than 10% refolding at 37 degrees C, whereas at 10 degrees C the recovery approaches 80%. The unfolding/refolding phases of the transition curves are most similar in the region of the transition, and refolding yields are significantly reduced when unfolded rhodanese is diluted to low urea concentrations, rather than to concentrations near the transition region. This is consistent with the formation of "sticky" intermediates that can remain soluble close to the transition region. Apparently, nonnative structures, e.g. aggregates, can form rapidly at low denaturant concentrations, and their subsequent conversion to the native structure is slow.

In Vitro Techniques↗
PubMed1991

Chaperonins facilitate the in vitro folding of monomeric mitochondrial rhodanese.

In vitro refolding of the monomeric mitochondrial enzyme, rhodanese (thiosulfate sulfurtransferase; EC 2.8.1.1) is facilitated by molecular chaperonins. The four components: two proteins from Escherichia coli, chaperonin 60 (groEL) and chaperonin 10 (groES), MgATP, and K+, are necessary for the in vitro folding of rhodanese. These were previously shown to be necessary for the in vitro folding of ribulose-1,5-bisphosphate carboxylase at temperatures in excess of 25 degrees C (Viitanen, P. V., Lubben, T. H., Reed, J., Goloubinoff, P., O'Keefe, D. P., and Lorimer, G. H. (1990) Biochemistry 29, 5665-5671). The labile folding intermediate, rhodanese-I, which rapidly aggregates at 37 degrees C in the absence of the chaperonins, can be stabilized by forming a binary complex with chaperonin 60. The discharge of the binary chaperonin 60-rhodanese-I complex, results in the formation of active rhodanese, and requires the presence of chaperonin 10. Optimal refolding is associated with a K(+)-dependent hydrolysis of ATP. At lower protein concentrations and 25 degrees C, where aggregation is reduced, a fraction of the rhodanese refolds to an active form in the absence of the chaperonins. This spontaneous refolding can be arrested by chaperonin 60. There is some refolding (approximately equal to 20%) when ATP is replaced by nonhydrolyzable analogs, but there is no refolding in the presence of ADP or AMP. ATP analogs may interfere with the interaction of rhodanese-I with the chaperonins. Nondenaturing detergents facilitate rhodanese refolding by interacting with exposed hydrophobic surfaces of folding intermediates and thereby prevent aggregation (Tandon, S., and Horowitz, P. (1986) J. Biol. Chem. 261, 15615-15618). The chaperonin proteins appear to play a similar role in as much as they can replace the detergents. Consistent with this view, chaperonin 60, but not chaperonin 10, binds 2-3 molecules of the hydrophobic fluorescent reporter, 1,1'-bi(4-anilino)naphthalene-S,5'-disulfonic acid, indicating the presence of hydrophobic surfaces on chaperonin 60. The number of bound probe molecules is reduced to 1-2 molecules when chaperonin 10 and MgATP are added. The results support a model in which chaperonins facilitate folding, at least in part, by interacting with partly folded intermediates, thus preventing the interactions of hydrophobic surfaces that lead to aggregation.

Adenosine Triphosphate↗
PubMed1990

Patient, parent, and staff attitudes toward allowing adolescent psychiatric inpatients to smoke.

A smoking attitude survey was developed and administered to adolescent patients, parents, and staff members at a psychiatric hospital for adolescents 6 months before and 6 months after the institution of a patient smoking ban. Attitudes before the ban were significantly more favorable toward allowing patient smoking than attitudes after the ban; smokers were significantly more in favor of allowing patient smoking than nonsmokers; and patients were significantly more in favor of allowing patient smoking than parents, who were significantly more in favor of allowing patient smoking than staff (overall ps less than 0.0001; post-hoc ps less than 0.05). The findings support the feasibility of implementing smoking bans in adolescent inpatient facilities.

Adolescent↗
PubMed1988

Pentafluorobenzylation of alkyl and related DNA base adducts facilitates their determination by electrophore detection.

The DNA adduct O4-ethylthymine can be alkylated under mild conditions with pentafluorobenzyl bromide. The product has good gas chromatographic characteristics and also forms a structurally characteristic anion in high yield when subjected to electron capture mass spectrometry. Related adducts for other DNA bases behave similarly. These properties stimulated us to develop a general analytical method based on the derivatization reaction. Important for this method is an oxidation-elimination reaction that mildly releases a base from a nucleoside. Thus, a general analytical method based on pentafluorobenzylation is now available for determining many alkyl and related DNA adducts.

Alkylation↗
PubMed1987

Controlled multicentre therapeutic trial of an unrefined carbohydrate, fibre rich diet in Crohn's disease.

Between 1 September 1980 and 31 August 1983, 352 patients with inactive or mildly active Crohn's disease but not taking drug treatment apart from sulphasalazine were entered from 40 hospitals into a prospective trial to assess the effects of two different diets on disease activity over two years. One hundred and sixty two patients were randomly allocated to take a diet unrestricted in sugar and low in fibre and 190 to a diet with little or no sugar and high in unrefined carbohydrate. No clear difference in clinical course was detected among patients who accepted the two different types of dietary advice.

Adolescent↗
PubMed1984

Anthracycline-induced cardiomyopathy in children: a report of six cases.

Although anthracycline antibiotics are among the most useful chemotherapy agents, the risk of producing cardiomyopathy and the absence of a reliable noninvasive technique to predict subclinical cardiomyopathy remain a major problem. We retrospectively reviewed our experience with anthracyclines over a 5-year period. Cardiomyopathy developed in 6 of 112 patients (5.3%) treated with anthracyclines and was fatal in 5 of the 6 patients. Our incidence and mortality rates are higher than those previously reported.

Adolescent↗
PubMed1984

Comparison between the bacterial and oligosaccharide content of ileostomy effluent in subjects taking diets rich in refined or unrefined carbohydrate.

Dietary surveys have shown that patients with Crohn's disease tend to eat more sucrose than control subjects and this investigation was undertaken to determine whether a diet rich in refined carbohydrate affects the bacterial flora of the terminal ileum. Ileostomy effluent in five patients with Crohn's disease and five with ulcerative colitis after two weeks on a diet rich in sucrose and refined cereal has been compared with the same period on a diet low in sucrose and rich in unrefined cereal. Observations were made hourly for nine hours after equicaloric breakfasts representing the two diets. The amount of ileostomy effluent was greater on the unrefined carbohydrate diet both in terms of wet weight (238 +/- 89 g vs 162 +/- 79 g, p less than 0.02) and dry weight (23 X 6 +/- 6.8 g vs 14.9 +/- 6.6 g, p less than 0.01); surprisingly, the amount of glucose and oligosaccharide was also greater (169 +/- 41 mg vs 82 +/- 26 mg, p less than 0.001) in all 10 volunteers. The bacteriological flora per gram was also higher on the unrefined carbohydrate diet after the test meal (p less than 0.02 between three and six hours) as a result of a general increase in all organisms. The relative proportions of the organisms did not vary between the two diets. No differences were detected between patients with ulcerative colitis and those with Crohn's disease.

Adult↗
PubMed1982

An analysis of fetotoxicity using biochemical endpoints of organ differentiation.

The biochemical differentiation of the brain, lungs, liver, and kidneys of the late gestation rat fetus was examined to characterize the immediate implications of retarded growth on fetal development. Initially, the normative profile of development of the brain (weight, DNA content, and protein content), lungs (weight and surfactant accumulation), liver (weight and glycogen deposition), and kidneys (weight, alkaline phosphatase activity, and protein content) was determined on gestation days 19, 20, 21, and 22 (day 1 = finding of sperm in the vaginal smear). Subsequently, five compounds known to induce fetotoxicity (chlorambucil, methyl salicylate, mirex, nitrofen, and toxaphene) were administered during organogenesis, and the effects on organ differentiation were determined in day 21 fetuses. The effects of fetal growth retardation resulting from exposure to exogenous agents were not equally distributed among the organs studied. The liver and kidney appeared more sensitive to insult by these agents than did the brain and lungs.

Animals↗
PubMed1981

Perinatal toxicity of endrin in rodents. II. Fetotoxic effects of prenatal exposure in rats and mice.

The fetotoxic potential of endrin in the CD rat and CD-1 mouse was investigated. Endrin was administered as a solution in corn oil to groups of pregnant animals by gastric intubation at multiple dose levels throughout the period of organogenesis. The dams were sacrificed prior to term and the fetuses were examined for skeletal and visceral anomalies. In addition, maternal livers and fetuses from rats in each dose level were analyzed for endrin content. In the mouse, endrin caused maternal liver enlargement at a dose of 0.5 mg/kg/day and reduced maternal weight gain at a dose of 1.0 mg/kg/day. Fetal weight and skeletal and visceral maturity were adversely affected at a dose of 1.0 mg/kg/day, but no teratogenic effect or embryo lethality was evident even at a dose level that produced maternal lethality (1.5 mg/kg/day). In the rat, endrin markedly reduced maternal weight at doses above 0.150 mg/kg/day but produced no apparent effects on the fetus. The data suggest that species differences in sensitivity to endrin may in part be due to differences in metabolism. Although endrin levels in rat fetuses at a maximally tolerated dosage level resembled those previously reported for the hamster, relatively less 12-ketoendrin was present, paralleling the change in fetal sensitivity.

Animals↗
PubMed1979

The fetotoxic potential of municipal drinking water in the mouse.

Mice (CD-1 strain) were placed on diets containing either municipal drinking water (Durham, North Carolina) or water that had been distilled and passed through cartridges to reduce organics and remove inorganics. After a two-week acclimation period, animals were bred and pregnancy confirmed by the presence of a sperm plug. During the 8-month course of the study, approximately 500 pregnant mice were sacrificed on day 18 of gestation and their fetuses examined for visceral and skeletal anomalies. No significant water-related effects were found on any fetal parameter studied except for a 28.1% incidence of supernumerary ribs in the tap-water group as compared to 21.1% in the purified-water group. No differences were noted in the type or occurrence of anomalies between the two groups. A month to month variation was observed in a number of parameters. The degree of variation was similar for the treatment groups, suggesting that these changes might be random fluctuations.

Abnormalities, Drug-Induced↗
PubMed1977

Abnormalities of leukotaxis in atopic dermatitis.

Leukocyte chemotaxis studies were performed in 14 patients with atopic dermatitis. Monocyte chemotactic responsiveness (MCR), polymorphonuclear leukocyte (PMN) chemotactic responsiveness (PCR), and patient serum inhibition of normal monocyte chemotaxis were evaluated. The most common defect noted was depressed MCR. This was found in 8 of the 14 patients and was associated with a chemotactic inhibitor in the serum of 5 of 6 of the 8 with depressed MCR whose sera were so tested. Depressed PCR was found in 3 of 10 patients studied. Ten of the 14 patients had depressed chemotaxis of at least one cell type. Depressed chemotaxis was not related to the presence of infection, to the serum IgE level, or to the severity of the eczema, and it could not be produced in vitro by incubating normal cells with histamine or IgE myeloma. These studies demonstrate a high frequency of leukocyte chemotactic abnormalities in patients with severe atopic dermatitis. Elucidation of the clinical significance of the leukotactic abnormalities observed and determination of whether they are basic or secondary to the disease process must await further study.

Adolescent↗