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Biomedical subjects

A Thomas

Publications and source records attributed to A Thomas.

At least 523 records · Page 29Linked to original sources
PubMed1981

Shutoff of neuroblastoma cell protein synthesis by Semliki Forest virus: loss of ability of crude initiation factors to recognize early Semliki Forest virus and host mRNA's.

A crude ribosomal wash containing the initiation factors of protein synthesis was isolated from mouse neuroblastoma cells 8 h after infection with Semliki Forest virus (SFV). The activity of this wash was compared with that of a wash from control cells in a cell-free protein-synthesizing "pH5" system, with early SFV mRNA (42S), late SFV mRNA (26S), encephalomyocarditis virus (EMC) mRNA, or neuroblastoma polyadenylated mRNA templates. A pronounced loss of activity (+/-80%) of the crude ribosomal wash from infected cells was observed with host mRNA (neuroblastoma polyadenylated mRNA) and early SFV mRNA, messengers which contain a cap structure at the 5' terminus. However, these washes were only slightly less active in systems programmed with (noncapped) EMC mRNA and late SFV mRNA. Although late SFV mRNA (26S) is capped, the synthesis of late (= structural) proteins in infected lysates was insensitive to inhibition by cap analogs. Purified initiation factors eIF-4B (M(r), 80,000) and cap-binding protein (M(r), 24,000) from reticulocytes (but none of the others) were able to restore the activity of infected factors to about 90% of control levels in systems programmed with early SFV mRNA and host mRNA. These observations indicate that infection-exposed crude initiation factors have a decreased level of eIF-4B and cap-binding protein activity. However, after partial purification of these and other initiation factors from infected and control cells, we found no significant difference in activity when model assay systems were used. Furthermore, both eIF-4B and cap-binding protein from infected cells were able to restore the activity of these infection-exposed factors to the same level obtained when these factors isolated from control cells or reticulocytes were added. A possible mechanism for the shutoff of host cell protein synthesis is discussed.

Animals↗
PubMed1981

The effects of NMR exposure on living organisms. I. A microbial assay.

Various bacterial strains have been exposed to a homogeneous magnetic field of 1 Tesla and to the conditions found in an NMR imaging experiment of the type used in a recent abdominal scan (Mansfield et al., 1978). No mutagenic or lethal effects were observed. The activity of the bacterial enzyme beta-galactosidase was also found to be independent of the applied magnetic field.

Bacteriophage lambda↗
PubMed1981

Use of environmental aids by adults with severe sensorineural hearing loss-an exploratory study.

In the course of a study to investigate the effect of severe hearing loss on family life it became apparent that many of the difficulties encountered could have been alleviated by the acquisition or better use of appropriate environmental aids. In some cases the problems were practical and in others social or psychological in nature. This paper consists of a detailed examination of such problems and discusses ways in which environmental aids could improve the quality of life for hearing impaired persons and their families.

Adult↗
PubMed1981

A validation study of the Hearing Measurement Scale.

The Hearing Measurement Scale was administered to 88 adults of employment age with severe to profound sensorineural hearing losses. A factor analysis of the scale confirms its overall validity with a few minor exceptions. A modified form of the scale is suggested for use with adults with severe to profound hearing impairment.

Adult↗
PubMed1981

A fatal case of salmonellosis in a dugong.

Salmonella lohbruegge was isolated from the kidney and the liver of a captive dugong calf (Dugong dugon) which died after an illness of at least several weeks. Clinical signs included diarrhoea and anorexia and were apparent for a week before death. Necropsy and histopathologic examination revealed thickening of the intestinal mucosa, epithelial degeneration, and epithelioid cell infiltration of mucosa, submucosa and contiguous smooth muscle. Enlargement of intestinal lymphoid tissue was apparent, and occasional focal granulomas were found in the liver. The source of the Salmonella infection was not ascertained.

Animals↗
PubMed1980

Purification and characterization of protein synthesis initiation factor eIF-3 from wheat germ.

eIF-3 from wheat germ is a large multicomponent factor. It sediments at 15 S and is comprised of ten different polypeptides with an Mr value ranging from 26 000 to 135 000; five out of the ten seem to be present in a 1 : 1 stoichiometric ratio, whereas the others appear to occur approximately in a 0.5 to 1 ratio. The factor is active in a partially purified cell-free system derived from wheat germ and in a mammalian model assay system for the synthesis of methionyl puromycin.

Cell-Free System↗
PubMed1980

The role of eIF-4C in protein synthesis initiation complex formation.

eIF-4C has a pronounced stimulatory effect on initiation complex formation with native 80-S ribosomes (80-Sn) as the only source of ribosomal subunits, but only a small effect when washed 40-S subunits are used. eIF-4C is accessary to eIF-3 in dissociating 80-Sn ribosomes. eIF-4C is present on 40-Sn but absent on 40-Sn dimers, which occur in preparations of native ribosomes and are as such inactive in protein synthesis. eIF-4C dissociates 40-Sn dimers into active monomers. These results can be explained by assuming that the presence of eIF-4C on 40-Sn prevents: (a) premature association with 60-S ribosomal subunits and (b) dimerisation, thus increasing the rate and extent of initiation complex formation.

Animals↗
PubMed1980

Immuno-histochemical characterisation of cells involved in dermatopathic lymphadenopathy.

Normal and pathological lymph nodes exhibiting the features of dermatopathic lymphadenopathy were analysed by immunochemical methods. Various antisera to human Ia-like antigens, to immunoglobulin, to T cells and myelo-monocytic cells were used. The paracortical enlargement typical of the condition was due to interdigitating cells containing Ia-like antigens on their membrane, and to adjacent T lymphocytes. The intensity of staining with anti-Ia-like serum on the interdigitating cells was comparable to the very strong staining of the fewer reticular cells present in the T dependent areas of normal nodes and normal spleen, and to the staining of Langerhans cells in the skin and appear to be higher than that seen on B lymphoid cells. These cells do not exhibit immunoglobulin and do not react with antisera made against circulating granulocytic and monocytic cells. Since sinus histiocytes of normal nodes and histiocytes in massive lymphadenopathy showed very weak staining with anti-Ia-like serum, strong Ia expression seems to be restricted to a subclass of mesenchymal cells which might be involved in the regulation of T cell function.

Atrophy↗
PubMed1980

Altered regulation of the recA gene in Escherichia coli strains carrying a recA-linked suppressor of lexA.

A mutant strain of E. coli displaying altered regulation of the recA gene was isolated as a revertant of a lexA3 recA200 double mutant which showed improved DNA repair and recombination functions. The mutant (alc-24) was located between srl and recA200 and caused synthesis of high levels of recA protein in both lexA+ and lexA3 strains. The possibility that alc-24 defines the regulatory site for recA is discussed.

Bacterial Proteins↗
PubMed1980

The mechanism of action of eukaryotic initiation factor 4C in protein synthesis.

Binding of eukaryotic initiation factor 4C (eIF-4C) to a 40-S initiation complex could be detected by analysis of assay mixtures for 40-S initiation complex formation on columns of Sepharose 6B and on sucrose gradients. On Sepharose 6B columns an almost stoichiometric binding of [14C]eIF-4C was observed, provided that eIF-1, eIF-2, eIF-3, Met-tRNAf and mRNA were included in the assay mixtures. On sucrose gradients the presence of 0.5 microM edeine was an additional prerequisite for stable binding of eIF-4C. The presence of eIF-4C on the 40-S initiation complex resulted in a pronounced increase of its stability, which might explain the observed stimulatory effect of the factor on the binding of Met-tRNAf into initiation complexes. The interaction between eIF-4C and the small ribosomal subunit presumably occurs at an early stage of the initiation process, since eIF-4C was capable of dissociating 80-S ribosomes into subunits. Protein synthesis in a 'pH-5' assay was almost totally dependent on the addition of eIF-4C, when the assay was performed with purified, nearly homogeneous, initiation factors.

Animals↗
PubMed1980

Control of hypertension in out-patients. Experience of the Glasgow Blood Pressure Clinic.

Five hundred and sixty-two patients who had attended the Glasgow Blood Pressure Clinic regularly for 3 years between 1969 and 1978 were studied. The mean BPs for the group were 187/115 mmHg initially, 157/100 mmHg after 6 months, and 153/98 mmHg after 3 years. Twenty-eight per cent had 'normal' systolic pressure and 22% 'normal' diastolic pressure at 3 years. Thirty-seven per cent with mild, 83% with moderate, and 89% with severe systolic pressure elevation had moved into less severe categories by 3 years, as had 30% with mild, 60% with moderate and 84% with severe diastolic evaluation. Those patients with severe hypertension, who did not attain a less grade, had a statistically significant drop in pressure. Four per cent of all patients, however, had moved into a more severe severe grade of systolic pressure evaluation and 6% into a more more severe diastolic pressure grade at 3 years. These results suggest that the hospital Hypertension Clinic can play a useful part in the lowering of BP in out-patients. It is clear, however, that 'normal' BP levels are not achieved in a significant proportion of patients.

Adolescent↗
PubMed1980

Social and psychological implications of acquired deafness for adults of employment age.

This is a summary report of the major findings of a study designed to examine the social and psychological implications of acquired deafness for adults of employment age, issued with a National Health Service hearing aid between 1970 and 1976 in the Greater London Area. Acquired deafness, long after rehabilitation, was found to cause considerable and serious personal unhappiness.

Adolescent↗
PubMed1980

A longitudinal study of human malaria in the West African Savanna in the absence of control measures: relationships between different Plasmodium species, in particular P. falciparum and P. malariae.

The research project in the epidemiology and control of malaria conducted in the Garki District, Kano State, jointly by the Government of Nigeria and the World Health Organization included among its objectives the study of the baseline epidemiology prior to the introduction of any control measures. The present paper analyzes the project's data with respect to the relationships among the three species of Plasmodium present, P. falciparum, P. malariae and P. ovale. Parasitemia with P. falciparum or P. malariae is more likely in the presence than in the absence of the other species. Among persons positive for P. falciparum, those with a higher density of parasitemia are more likely to have P. malariae also than those with a lower density of P. falciparum parasitemia. There is a pronounced seasonal alternation in prevalence between P. falciparum and P. malariae.

Adolescent↗