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Biomedical subjects

R Lewis

Publications and source records attributed to R Lewis.

At least 217 records · Page 12Linked to original sources
PubMed1987

Expression of HLA-DR and OKT6 antigens on keratinocytes and dendritic cells in pemphigus.

The expression of HLA-DR and OKT6 antigens by epidermal cells in pemphigus was examined by immunohistochemical methods using skin biopsy specimens from human patients with pemphigus vulgaris. Changes in the distribution and subpopulations of Langerhans cells were observed in lesional (involved) skin. HLA-DR-positive, OKT6-negative dendritic cells were numerous and generally confined to the margins of epidermal clefts. OKT6-positive dendritic cells were rare or absent in lesional skin. The HLA-DR-positive, OKT6-negative dendritic cells associated with intraepidermal clefts are most likely functionally active antigen-presenting cells, which may play a role in lesion development. Aberrant expression of HLA-DR molecules by keratinocytes was observed in both involved and uninvolved skin, and may function to facilitate the recognition of surface-bound pemphigus antigen(s) by immunocompetent cells.

Antibodies, Monoclonal↗
PubMed1987

A shared B-T cell phenotype in autoimmune mice bearing the lpr gene.

MRL-lpr mice and MRL-+/+ mice are identical except for the presence of an autosomal recessive lymphoproliferation gene (designated lpr) in the former. Mice bearing the lpr gene develop autoimmune and lymphoproliferative abnormalities. An antigenic marker designated 14D10, characteristically expressed on the surface of Lyt-2+ T cells and B cells of normal mice, is expressed in unusually high levels on Thy-1+ cells of lpr mice which are Lyt-2-. In younger lpr animals, 14D10+ cells are a minor subpopulation of Ia+ cells which, when expanded in diseased animals, continue to express Ia. 14D10+ cells from lpr mice are elevated in fetal spleen and adult bone marrow (BM) but are absent on pre-B cells in the BM. Medullary thymocytes of lpr mice are enriched in 14D10+ cells compared to congenic (+/+) controls. Although 14D10 appears to be present on the activated, proliferating T-cell population, coculture of lpr cells with IL-2 leads to minimal proliferation. 14D10+ Lyt-2- T cells can be isolated from normal spleens, indicating the lpr gene may be responsible for the disregulated proliferation of a minor cell subset. The functional significance of this molecular complex is still undetermined.

Animals↗
PubMed1987

Investigation of Clostridium difficile diarrhoea in a district general hospital: room for improvement?

A retrospective survey of case-notes was carried out on all patients investigated for possible Clostridium difficile diarrhoea during a 1-month period at a district general hospital. Seven of 29 patients probably had the disease, but no case of pseudomembranous colitis was documented. Delay in reporting and discrepancies between culture and cytotoxin results contributed in several cases to mismanagement. In 14 of 16 cases negative by culture and cytotoxin, a plausible non-microbiological case for diarrhoea was found, including aperients in six.

Adult↗
PubMed1987

A comparison of verapamil and digoxin in the treatment of atrial fibrillation.

Twelve patients (including 2 females) with chronic atrial fibrillation were entered into a randomized, double blind crossover study to compare the effects of digoxin and verapamil upon heart rate, exercise tolerance and symptom control. The dose of digoxin was adjusted so as to give serum concentrations within the range 1.3 to 2.6 nmol l-1 between four and six hours after dosing, and was continued for six weeks. The dose of verapamil was increased from 40 mg tds to 80 mg tds to 120 mg tds at fortnightly intervals. Three patients did not complete the study; two because of adverse effects attributable to verapamil. In the remaining nine patients, mean post exercise heart rates were significantly lower during treatment with verapamil 80 mgs tds (126.7 bpm) than with verapamil 40 mg tds (148.6 bpm) or digoxin (146.7 bpm). However, exercise tolerance was similar with both verapamil and digoxin and the superior control of exercise induced tachycardia achieved with higher doses of verapamil was not associated with improved exercise endurance. Visual analogue scale scores for constipation were significantly higher during treatment with verapamil; scores for other possible side effects and for overall wellbeing were similar. The results do not confirm the findings of others who have reported that verapamil is superior to digoxin in the treatment of atrial fibrillation.

Aged↗
PubMed1987

Moxalactam as single-agent prophylaxis in the prevention of wound infection following colon surgery.

A single agent systemic antibiotic (moxalactam) when used prophylactically in patients undergoing colon surgery was associated with a wound infection rate comparable to that achieved by a combination of oral neomycin and intravenous metronidazole. The data obtained demonstrated that the reduced infection rate was not the result of a reduction in the bacterial content of the colon alone but due to the prophylactic agents used for elective colon surgery.

Aged↗
PubMed1987

Beta-oxidized N-nitrosoalkylcarbamates as models for DNA alkylation by N-nitrosobis(2-oxopropyl)amine in Syrian hamsters.

A single dose of N-nitrosobis(2-oxopropyl)amine (NDOPA) can selectively induce pancreatic-duct adenocarcinomas in Syrian hamsters. Multiple doses or a higher single dose can induce tumours of the liver and other organs. Our earlier studies employing NDOPA systematically labelled with 14C in the three-carbon chain showed that hamster pancreatic DNA is almost exclusively methylated and that the sole source of the methyl group is the alpha carbon of NDOPA. Hamster liver DNA was equally methylated and alkylated by a three-carbon chain. Current studies using generally labelled tritiated NDOPA with a very high specific activity have shown that the three-carbon alkylation is 2-hydroxypropylation. We have identified two adducts isolated from hamster liver DNA, N7-(2-hydroxypropyl)-guanine and O6-(2-hydroxypropyl)guanine, which contain this group, and we have also isolated and identified N7-methylguanine and O6-methylguanine in DNA from hamster liver and pancreas. beta-Oxidized N-nitrosocarbamates, ethyl N-nitroso-2-oxopropylcarbamate (NOPC) and ethyl N-nitroso-2-hydroxypropylcarbamate (NHPC), are useful models for predicting the DNA adducts observed in vivo following NDOPA treatment. Base-catalysed decomposition of NOPC in the presence of exogenous DNA yields five methylated purines (N3-, N7- and O6-methylguanines and N1- and N3-methyladenines). NHPC, a model for N-nitrosamines containing the 2-hydroxypropyl group, reacts with guanosine to yield N7- and O6-(2-hydroxypropyl)guanines.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1986

Primary structure of the chromosomal protein HMb from the archaebacteria Methanosarcina barkeri.

The amino acid sequence of the protein HMb, a protein of 93 residues (Mr 10757) which represents the major acid-soluble component of the Methanosarcina barkeri nucleoprotein complex, has been established from automated sequence analysis of the protein and from structural data provided by peptides derived from cleavage of the protein at aspartic acid, arginine and methionine residues. The protein HMb is mainly characterized by a high amount of charged residues (15% of acidic residues and 26.8% of basic residues) which are distributed all along the polypeptide chain. The amino acid sequence of the protein HMb is not homologous to any eubacterial, archaebacterial or eukaryotic chromosomal proteins known up to now.

Amino Acid Sequence↗
PubMed1986

Differential sensitivity of the WAIS and a modified Halstead-Reitan battery to severity of brain dysfunction in epilepsy.

The present study examined the diagnostic sensitivity of the WAIS relative to a modified Halstead-Reitan test battery by comparing the accuracy of these instruments in differentiating pseudoneurologic control subjects from two groups of epileptics which were believed to differ in degree of underlying brain pathology. A total of 96 subjects were equally represented in the control, mildly impaired, and moderately impaired study groups. Separate three-group and two-group discriminant function analyses were performed for the two sets of measures. Comparisons of kappa coefficients indicated that the WAIS was inferior in classification accuracy to the neuropsychological tests in making the three-group discriminations and in separating the mildly impaired subjects from the moderately impaired group. These findings suggest that the WAIS may be inferior in discriminatory power relative to a wider array of neuropsychological measures than has heretofore been evaluated. Furthermore, these data imply that the degree of underlying brain involvement associated with a seizure disorder may be determined best from neuropsychological tests rather than from a general measure of intellectual ability, such as the WAIS.

Journal Article↗