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Biomedical subjects

G S Johnson

Publications and source records attributed to G S Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1972

Differences in opportunities for the disabled in England and Scotland: a survey of paraplegics in Scotland.

The facilities available to disabled people living in Scotland were studied by visiting and interviewing a group of 50 paraplegics living in Glasgow and the surrounding counties. The degree of unemployment in the group (74%) was far greater than has been reported in other surveys, and no quadriplegic was in remunerative employment. Though the general unemployment level in the area is high services to help the disabled gain employment were only partially utilized.Liaison between social workers was not always successful. Some paraplegics were visited at home by both a medical social worker and a local authority social worker, while others were not supported by either. There was no apparent attempt by local authorities to identify the disabled, as is required in England under Section 1 of the Chronically Sick and Disabled Persons Act, 1970. Several paraplegics lacked facilities which are covered by Section 2 of the Act. The exclusion of Scotland from Sections 1 and 2 of the Chronically Sick and Disabled Persons Act may widen the differences between the two countries as the Scottish legislation is less specific.

Adolescent↗
PubMed1972

Isolation and characterization of myosin from cloned mouse fibroblasts.

Myosin has been isolated from cloned mouse fibroblasts, line L-929. Fibroblast myosin: (i) binds to rabbit muscle actin and is dissociated from it by ATP, (ii) has an ATPase activity that is suppressed by Mg(2+) in 0.6 M KCl and is activated by rabbit muscle actin in the presence of Mg(2+) in 14 mM KCl, (iii) forms thin bipolar aggregates in 0.1 M KCl when viewed in the electron microscope, (iv) possesses a heavy chain with the same mobility as muscle myosin (molecular weight 200,000) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In these respects, fibroblast myosin appears to be similar to muscle myosin in structure and function.

Actins↗
PubMed1972

Regulation of adenosine 3',5'-cyclic monophosphate phosphodiesterase activity in fibroblasts by intracellular concentrations of cyclic adenosine monophosphate (3T3-dibutyryl cyclic AMP-SV40-transformed cells-michaelis constants-L cells-prostaglandin E 1 ).

Cyclic AMP-phosphodiesterase is present in various mouse fibroblasts. Contact-inhibited 3T3 cells contain two forms of the enzyme, one with a K(m) of 2.5 muM and the second with a K(m) of 71 muM. As 3T3 cells grow to confluency and cAMP concentrations rise, the activity of the first enzyme increases, whereas that of the second is unchanged. A line of SV40-transformed 3T3 cells with low cAMP concentration also has low levels of the cAMP-phosphodiesterase with a K(m) of 2.5 muM. Treatment of 3T3 and SV40-transformed 3T3 cells with dibutyryl cAMP and theophylline increases cAMP-phosphodiesterase accumulation. This accumulation is blocked by cycloheximide and actinomycin D. The newly formed enzyme resembles the higher affinity enzyme present in unstimulated cells, since it has a K(m) of 1.2-2.0 muM, and is stimulated by snake venom. In L cells in which cAMP concentrations are elevated by treatment with prostaglandin E(1), cAMP phosphodiesterase also accumulates. We conclude that intracellular concentrations of cAMP regulate the synthesis of cAMP-phosphodiesterase, and that cAMP functions as an inducer of the enzyme.

Animals↗
PubMed1971

Restoration of several morphological characteristics of normal fibroblasts in sarcoma cells treated with adenosine-3':5'-cyclic monphosphate and its derivatives.

Sarcoma cells growing in tissue culture have morphological and growth characteristics different than normal fibroblasts. Several of the morphological characteristics of normal fibroblasts are regained when the cells are incubated with dibutyryl-cyclic AMP or butyryl-cyclic AMP (0.1-1 mM), or cyclic AMP (3 mM) plus theophylline (1 mM), but not with ATP, ADP, AMP, adenine, or adenosine (1-7 mM). The cell bodies become elongated; distinct narrow processes are formed. With prolonged incubation, the cells show less tendency to pile up or become polygonal. Further, L-929 and Rous sarcomatransformed hamster cells orient in parallel arrays characteristic of contact inhibition. The cells retain their altered morphology as long as the butyryl-cyclic AMP is present, but revert after its removal. Experiments with cycloheximide, puromycin, and actinomycin D indicate that protein Synthesis, but not RNA synthesis, is required for the response. Microtubular proteins may be involved. No response is observed with normal fibroblasts or with various epithelial cells. The data suggest that cyclic AMP may be an important factor in the determination of morphology of normal fibroblasts and this function may be lost or altered during transformation.

Adenine Nucleotides↗
PubMed1971

Analysis of the fusion of XC cells induced by homogenates of murine leukemia virus-infected cells and by purified murine leukemia virus.

The fusion of XC cells induced by murine leukemia virus (MuLV)-infected cells is also induced by homogenates prepared from the infected cells and by purified MuLV. The fusion-inducing factor appears to contain a heat-labile lipoprotein. No synthesis of specific macromolecules by the XC cells is necessary to obtain fusion. The results suggest that specific components of the viral particle are the activators for the fusion process and they may also be present in the membranes of infected cells.

Animals↗
PubMedDate not supplied

Protein alterations in olfactory neuroblasts from Alzheimer donors.

Definitive diagnosis of Alzheimer's disease (AD) is made by pathologic examination of postmortem brain tissue in conjunction with a clinical history of dementia. To date, there are no good biological markers for a positive diagnosis of AD in the living patient. In an effort to identify biological markers useful both in the clinical and pathologic diagnosis of AD, we have investigated disease-specific protein alterations in cultured olfactory neurons. Olfactory neurons are readily accessible by biopsy, can be propagated in primary cell culture as olfactory neuroblasts (ONs), and exhibit several elements of AD brain pathophysiology making them powerful tools for the study of AD. Two-dimensional gel analysis of ON proteins from neuropsychologically evaluated AD donors revealed a set of five proteins (Mr 17-50 kD, pI 4.8-6.7) that were significantly altered in concentration when compared to cells from age-matched controls. Further characterization and microsequence analysis could lead to the identification of proteins that may have important diagnostic or therapeutic value in the treatment of AD.

Aged↗