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Biomedical subjects

A Thomas

Publications and source records attributed to A Thomas.

At least 505 records · Page 28Linked to original sources
PubMed1983

Control of recA dependent activities in Escherichia coli: a possible role for the recF product.

DNA repair and genetic recombination have been studied in recF143 mutants of Escherichia coli in which expression of inducible, SOS repair activities was altered by additional mutations either in lexA or recA. recF143 and lexA3 appeared to act additively to increase sensitivity to UV irradiation and to reduce recombination proficiency. The recF defect was suppressed in strains carrying the tif-1 allele of recA but not in strains carrying mutations that increased synthesis of recA+ protein or which directly inactivated lexA repressor. These and other data are interpreted to suggest that the recF defect is related to a reduced activity of recA protein. The implications of these findings are discussed in relation to the control of SOS activities and cell division during normal growth.

Bacterial Proteins↗
PubMed1982

Temperament and follow-up to adulthood.

A follow-up of the New York longitudinal study at the 18-22-year period has been completed. Only one of the 133 subjects was not interviewed and evaluated. A temperament questionnaire for this age period has also been developed and given to 70 of the subjects. From the interview, ratings of temperament, adjustment and clinical psychiatric status were made. Statistical correlations showed significant relationships between 'difficult-easy' temperament at three and five years of age and early adult 'difficult-easy' temperament, adjustment, and presence or absence of a clinical psychiatric diagnosis. The importance of qualitative analyses of idiosyncratic developmental factors in individual cases is emphasized.

Adult↗
PubMed1982

Reentry confined to the atrioventricular node: electrophysiologic and anatomic findings.

A patient with recurrent disabling, paroxysmal supraventricular tachycardia refractory to drug treatment underwent electrophysiologic studies. The paroxysmal supraventricular tachycardia was found to be due to atrioventricular (A-V) nodal reentry. The patient died shortly after surgical His bundle section and detailed anatomic studies were performed. These showed fatty infiltration of the approaches to the sinoatrial node, atrial preferential pathways, and A-V node and common bundle. The A-V node was mechanically damaged and the common His bundle was completely severed. These abnormalities were clearly delineated and there was no evidence of an atrio-His bundle bypass tract to an accessory A-V node. Specifically, the central fibrous body and pars membranacea were defined and no atrial muscular fibers pierced these structures to joint the A-V bundle. It is concluded that paroxysmal supraventricular tachycardia due to A-V nodal reentry can be confined to the A-V node.

Atrioventricular Node↗
PubMed1982

Implantation of the automatic defibrillator: the subxiphoid approach.

The automatic implantable defibrillator is an electronic device capable of diagnosing and correcting malignant venticular arrhythmias. While major thoracic surgery was required in the original 24 implants, a new technique for implanting the device has been developed. The first subxiphoid implantations have been accomplished with the defibrillatory function successfully tested intraoperatively. The advantages and indications of the subxiphoid technique are reviewed.

Arrhythmias, Cardiac↗
PubMed1982

Cytogenetic and histological studies in a series of subfertile males.

Cytogenetic and histological studies were carried out on a series of 68 men during investigations for subfertility. Somatic chromosome analysis identified 4 cases with abnormal karyotypes. Meiotic chromosome analysis identified 4 cases with abnormal meiosis. Analysis of cell stages of the spermatogenic cycle in cytogenetic preparations identified 12 cases with missing cell cycle stages. Histological analysis of tissue samples identified defects of the spermatogenic cycle in 23 cases. A kinetic model of spermatogenesis is used in order to relate the different types of abnormality to the spermatogenic cycle.

Adult↗
PubMed1982

Problems encountered at work by people with severe acquired hearing loss.

A structured questionnaire concerning problems encountered at work was administered to 88 adults of employment age suffering from acquired sensorineural hearing loss (60 dB +). While respondents were not likely to be out of work by virtue of their hearing loss, they found it difficult to cope at work for a variety of reasons. Information from a subsequent open-ended interview threw some light on the validity of the questionnaire and in particular illustrated the need to combine quantitative and qualitative methods of data collection.

Adult↗
PubMed1982

Circulating immune complexes in Plasmodium knowlesi infected Kra, and merozoite vaccinated Rhesus monkeys.

The presence of circulating soluble immune complexes that bind the C1q component of complement has been determined in the sera of two monkey species showing different degrees of clinical immunity to Plasmodium knowlesi infection. Material binding C1q was found in the serum of both primarily infected Kra monkeys and post-vaccinated immune Rhesus monkeys following the onset of parasitaemia. The complexes then disappeared from the circulation of Kra monkeys despite continuing low-grade parasitaemia, but in Rhesus monkeys C1q binding material remained detectable for up to 3 weeks after apparent elimination of parasites. The ability of complexes to bind C1q was removed by reduction and alkylation and binding material was absorbed by staphylococcal protein A suggesting the presence of Ig. Further analysis of the binding material is required to fully establish its constitution and possible immunoregulatory function at different stages of infection in the two monkey species.

Animals↗
PubMed1982

Multifocal defects and splenomegaly in sarcoidosis: a new scintigraphic pattern.

Sarcoidosis involves the spleen in a significant percentage of patients afflicted with this disease. The most commonly applied modality for studying such patients is the (99m)Tc-sulfur colloid scan. Different patterns have been recognized: "normal" spleen and nonspecific splenic enlargement, with or without focal areas of photon deficiency, which was thought to represent an infarction in a previous report. We have encountered two patients showing splenomegaly and multifocal photon deficiencies secondary to sarcoid granulomata. These cases are presented to inform clinicians of a new pattern. Our patients were managed with systemic corticosteroids and palliation of pain. If symptoms persist or worsen, splenectomy may be necessary to avoid spontaneous rupture. An abbreviated differential diagnosis of the enlarged spleen with multiple focal defects is discussed.

Adult↗
PubMed1981

The protein synthetic activity in vitro of ribosomes differing in the extent of phosphorylation of their ribosomal proteins.

We describe a re-examination of the cell-free protein synthetic activity of eukaryotic ribosomes having proteins phosphorylated to different extents. Ribosomal 40 S subunits were isolated both from a variety of cells in which there is relatively little phosphorylation of ribosomal protein S6, and from cells subjected in vivo to different stimuli that promote the extensive phosphorylation of protein S6. The ability of these subunits to bind Met-tRNA as well as the second amino acyl-tRNA (Val-tRNA) was compared in the presence of highly purified initiation factors, elongation factor EF-1 at various concentrations of 60S subunits, 9 S globin mRNA and potassium ions. The ability of the subunits to synthesize polyphenylalanine was also studied using highly purified elongation factors. In no case was any significant difference in activity observed between ribosomes with protein S6 phosphorylated to different extents. Similar, though less extensive, studies were preformed comparing 60 S ribosomal subunits differing in the extent of phosphorylation of the acidic phosphoprotein, L gamma , and of L14. No difference in activity was observed between these ribosomes.

Animals↗
PubMed1981

[The bacteria stop system of Meierhans-Weber as room air technical alternative to laminar-air-flow and its air hygienic effectiveness].

Statistics of wound infections demonstrate the linear dependence between postoperative wound infection and the quantity of bacteria in the air of operating theatres. In the most extensive examination series we have made as yet with a special work group of DGOT the quantity of bacteria in the air of non air-conditioned operating theatres and such fitted out with different aircleaning systems was determined. Non air-conditioned operating theatres proved so extremely infected that the risk of wound infection cannot be borne any more in the future. Also air-conditioned systems according to DIN 1946/4 with an average of 190 bacteria/m3 are not sufficiently secure for bone and joint surgery. In Switzerland for such operations a value of 10/m3 at the most is admissible. Such equivalents have been attained only with LAF until today. After extensive air tests the so-called "Keimstop"-system by Meierhans and Weber is to be considered the sole system suitable to supplement air conditioning DIN 1946/4. This combination yields the same effect as the expensive LAF systems.

Air Conditioning↗
PubMed1981

Mechanisms for albumin-mediated membrane damage.

1. Bee venom phospholipase A2 causes a small increase in the sublytic leakiness of rabbit erythrocytes which is strongly inhibited by lysolecithin and potentiated by albumin. 2. Albumin extracts long-chain fatty acids from the erythrocyte membrane by a process which is faster than diffusion-determined efflux of fatty acid and during the process it greatly increases the sublytic leakiness of the membrane. In contrast, albumin rapidly terminates sublytic responses to lysolecithin. 3. These actions of albumin are abolished only when albumin is preloaded with four molecules of oleic acid per protein molecule. 4. A minor proportion of the response of phospholipase-A2-treated cells to albumin is due to accumulated fatty acid products; the combination of active enzyme and accumulated fatty acids is much more effective than either alone. Membrane partially depleted of phospholipids by enzyme attack is not highly leaky. 5. Albumin may, in part, act by removing lysolecithin, the inhibitory reaction product. A model is proposed in which susceptibility to phospholipase A2 attack is not uniform on the cell surface and is used to explain the inhibitory action of lysolecithin and the high sensitivity of the membrane in the presence of albumin to damage by newly released fatty acids.

Animals↗