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Biomedical subjects

A Crawford

Publications and source records attributed to A Crawford.

At least 73 records · Page 4Linked to original sources
PubMed1986

Formaldehyde metabolism by Escherichia coli. Detection by in vivo 13C NMR spectroscopy of S-(hydroxymethyl)glutathione as a transient intracellular intermediate.

In vivo 13C NMR has been used to detect the transient formation of S-(hydroxymethyl)glutathione (GSCH2OH) from glutathione and [13C]formaldehyde in Escherichia coli. Two-dimensional 1H-13C shift correlation was used to locate the chemical shift of the formaldehyde-derived protons of the adduct. The adduct GSCH2OH is formed by chemical reaction in the first few minutes after cells are challenged with formaldehyde and remains within the cell until consumed by metabolism.

Carbon Isotopes↗
PubMed1986

The effect of interleukin-1 on connective tissue metabolism and its relevance to arthritis.

Interleukin-1 (IL-1) is the name given to a family of related proteins showing a variety of activities. It was originally shown to be produced by monocytes and macrophages but is now known to be produced by numerous cell types, including synovial cells. From the point of view of arthritis, its most interesting activities are those on connective tissue cells in vitro. These include stimulation of production of prostaglandins, plasminogen activator and metalloproteinases such as collagenase and proteoglycanase. IL-1 is also mitogenic for synoviocytes and bone cells, and can alter rates of production of extracellular matrix constituents. The presence of IL-1 in synovial fluids from rheumatoid and osteoarthritic joints and its actions on connective tissues in vitro suggest that IL-1 may play an important role in the pathogenesis of arthritis. There are several potential cellular sources of IL-1 in the inflamed rheumatoid joint and interactions between these cells, T lymphocytes and plasma cells may continually induce IL-1 so contributing to the chronicity of the disease. The mechanism of action of IL-1 on connective tissue cells is at present uncertain though preliminary studies suggest that IL-1 may induce cellular responses by stimulating phosphoinositide turnover and possibly protein kinase C activity.

Arthritis, Rheumatoid↗
PubMed1986

Adults at risk: a comparison of heavy drinkers in three areas of Britain.

This paper further investigates causes of the considerable variation in official statistics for alcohol-related problems which exist between the Highland, Tayside and Kent areas of Britain. This variation does not appear to be explained by differences in the consumption patterns of respondents drawn from the general populations of each area who exceeded various safe drinking limits.

Adolescent↗
PubMed1984

Regional variations in British alcohol morbidity rates: a myth uncovered? I: Clinical surveys.

Officially recorded rates of many alcohol related problems are much higher in the north than in the south of Britain. To try to shed some light on this the pattern and threshold for use of psychiatric and medical hospital services for alcohol dependence, abuse, and psychosis were studied in three areas differing greatly in official rates of alcohol related problems--namely, the Highland and Tayside regions in Scotland and part of the South East Thames region in England. The disparity in psychiatric admissions for alcohol dependence, abuse, and psychosis were found to be largely explained by admission policies which reflected geographical factors. The results of this study did not support the conventional view that rates of treated morbidity due to alcohol are appreciably higher in the north.

Alcohol Drinking↗
PubMed1984

Regional variations in British alcohol morbidity rates: a myth uncovered? II: population surveys.

Regional variations in officially recorded rates of alcohol related morbidity in Britain were investigated by surveying community drinking habits of a randomly selected sample of adults in the Highlands, Tayside, and part of the South East Thames region. Contrary to expectations, patterns of alcohol consumption did not differ in a manner consistent with the much higher rates of alcohol related problems recorded in the north.

Adolescent↗
PubMed1984

Response rates in British general population surveys of alcohol consumption: a comparison.

A review of response rates obtained in 17 British general population surveys of alcohol consumption is presented. Response rates ranged between 66.8 and 90% (M = 78.5 +/- 8.0). High response rates were most likely when unlimited visits to establish contact were allowed. It is suggested that expensive efforts to enhance response rates in such studies may be unnecessary. No clear evidence of declining response rates was found.

Adolescent↗
PubMed1982

Adenylate cyclase of human articular chondrocytes. Responsiveness to prostaglandins and other hormones.

Adenylate cyclase [ATP pyrophosphate lyase (cyclizing), EC 4.6.1.1] was shown to be present in cultured human articular chondrocytes. Optimal conditions of incubation time, protein and substrate concentrations and pH were determined in whole cell lysates. Maximal activity occurred at pH 8.5 with no decrease in activity up to pH 10.0. Adenylate cyclase activity of particulate membrane preparations was enhanced by the addition of crude cytosol preparations. The prostaglandins E1, E2, F1 alpha, F2 alpha, D2, B1, B2, A1 and A2, as well as adrenaline and isoprenaline, stimulated adenylate cyclase derived from either adult or foetal chondrocytes. No significant stimulation was observed in the presence of human calcitonin or glucagon. Bovine parathyroid hormone always significantly stimulated the adenylate cyclase derived from foetal chondrocytes, but not from adult chondrocytes. Preincubation of the chondrocytes in culture with indomethacin and with or without supernatant medium from cultured mononuclear cells increased the responsiveness of the adenylate cyclase to prostaglandin E1.

Adenylyl Cyclases↗
PubMed1980

Stimulation of hormone-responsive adenylate cyclase activity by a factor present in the cell cytosol.

1. Homogenates of whole tissues were shown to contain both intracellular and extracellular factors that affected particulate adenylate cyclase activity in vitro. Factors present in the extracellular fluids produced an inhibition of basal, hormone- and fluoride-stimulated enzyme activity but factors present in the cell cytosol increased hormone-stimulated activity with relatively little effect on basal or fluoride-stimulated enzyme activity. 2. The existence of this cytosol factor or factors was investigated using freshly isolated human platelets, freshly isolated rat hepatocytes, and cultured cells derived from rat osteogenic sarcoma, rat calvaria, mouse melanoma, pig aortic endothelium, human articular cartilage chondrocytes and human bronchial carcinoma (BEN) cells. 3. The stimulation of the hormone response by the cytosol factor ranged from 60 to 890% depending on the tissue of origin of the adenylate cyclase. 4. In each case the behaviour of the factor was similar to the action of GTP on that particular adenylate cyclase preparation. 5. No evidence of tissue or species specificity was found, as cytosols stimulated adenylate cyclase from their own and unrelated tissues to the same degree. 6. In the human platelet, the inclusion of the cytosol in the assay of adenylate cyclase increased the rate of enzyme activity in response to stimulation by prostaglandin E1 without affecting the amount of prostaglandin E1 required for half-maximal stimulation or the characteristics of enzyme activation by prostaglandin E.

Adenylyl Cyclases↗
PubMed1980

Properties of a factor in cytosol that enhances hormones-stimulated adenylate cyclase activity.

1. The addition of 50 000g cytosol preparations of isolated human platelets, cultured rat osteogenic sarcoma or cultured bone cells to particulate preparations of adenylate cyclase, from the same or unrelated tissues, caused marked enhancement of the hormone-stimulated enzyme activities. 2. The degree of enhancement obtained by addition of the cytosol preparations was similar to that observed on addition of GTP. 3. The enhancing activity of the three cytosol types was found to be sensitive to digestion by trypsin and alkaline phosphatase, partially heat-labile and partially inactivated by exposure to charcoal. 4. Gel filtration studies indicated an apparent molecular weight of 20 000--30 000. Further, the 20000-30000-mol.wt. fractions obtained by gel filtration could enhance the adenylate cyclase activity of particulate preparations derived from unrelated cell types. 5. The results suggest a common or similar adenylate-cyclase-enhancing factor or factors, protein in nature, present in the three cytosol types.

Adenylyl Cyclases↗