Search PubMed⌕ Search

Biomedical subjects

J Clark

Publications and source records attributed to J Clark.

At least 433 records · Page 24Linked to original sources
PubMed1981

Superoxide dismutase in Didymium iridis: characterization and changes in activity during senescence and sporulation.

The myxomycete Didymium iridis displays a single cytoplasmic superoxide dismutase in the diploid plasmodial stage. The enzyme was purified and appears to be a manganese-containing protein of approximately 32000 molecular weight. Superoxide dismutase specific activity was constant throughout the cell cycle and showed no significant change over the majority of plasmodial life span. Elevated superoxide dismutase activity, relative to that of other cytoplasmic enzymes, occurred during necrosis of senescent plasmodia, staling, and starvation-induced sporulation.

Cell Cycle↗
PubMed1981

The effect of isoperistaltic jejunal interposition upon gastric emptying.

Ten patients with severe postgastrectomy-postvagotomy symptoms, all of whom had the features of vasomotor dumping, underwent gastric emptying studies, using a 300 milliliter meal of 15 per cent dextrose labeled with 99mTc-sulphur colloid. Studies were repeated two to 11 months following remedial operative treatment, using a 12.5 to 15.0 centimeter isoperistaltic jejunal interposition. Preoperatively, all patients had rapid gastric emptying with a typical biphasic pattern. Following isoperistaltic interposition, the rate of gastric emptying was similar to that found in control patients. Gastric emptying reverted to a more normal pattern but, as in the preoperative studies, was best described by a double exponential function, consisting of slow and fast components. Analysis of these particular functions suggests the manner in which isoperistaltic interposition modified the underlying disorder of gastric motility.

Adult↗
PubMed1980

Evidence for the flutter valve mechanism of the lower oesophageal high pressure zone.

Simultaneous oesophageal manometry and pH monitoring was performed at rest and during abdominal compression in 189 subjects. The force exerted by the high pressure zone (HPZ) and by its intra-abdominal segment was reduced to the same extent in the 102 subjects who refluxed and the 87 who did not. Reflux during abdominal compression occurred in the subjects whose HPZ force fell into a critical range and in whom the contribution by the abdominal segment was reduced to less than 50 per cent of the total force exerted by the HPZ. These results are more in keeping with a mechanical flutter valve theory of lower oesophageal competence than sphincteric reflux control. Furthermore, the results indicate that measurements of oesophageal pressure, length or force in the resting state do not account for reflux or gastrooesophageal competence, but that it is the reserve of pressure, length or force during stress which is responsible.

Abdomen↗
PubMed1980

A second generation portable life support system.

Recognizing the need to transport critically ill patients to a specialized facility, we have designed a profound life support system. PLSS addresses the demand for mobility by placing all support systems under a patient cart. It addresses the demand for reliable power supply by providing a redundancy in sources. Ease of operation and further reliability are attained by automation. This system incorporates existing life support technology. Improvement is gained by combining the merits of several systems as well as by providing for portability. A synergistic effect which is obtained by combining IABP and VABP makes this portable device a unique and powerful clinical tool.

Critical Care↗
PubMed1980

Microcarriers for animal cell culture: a brief review of theory and practice.

Microcarrier beads for animal cell culture are considered in relation to aspects of cell adhesion and growth. Some "critical parameters" for a successful microcarrier are discussed, comparing currently available materials. The properties most critical for a successful microcarrier were closely fulfilled by the microcarrier CytodexTM 1 which has been used for the successful cultivation of more than 60 different cell types. Cytodex 1 has been used for the culture of primary cells, normal diploid cell strains and established or transformed cell lines in culture volumes ranging from a few millilitres to over 100 litres.

Animals↗
PubMed1980

Critical parameters in the microcarrier culture of animal cells.

The successful culture of over 60 different cell types on Cytodex TM1 microcarriers has enabled identification of parameters critical for obtaining high cell yields from microcarrier cultures. Careful control of the initial phase of microcarrier culture was found to be critical. Increasing cell density, reducing culture volume and reducing stirring rate during the initial phase all assisted in improving cell yields. Control of pH, inoculum condition, nutrient supply and serum quality, and elimination of mycoplasma were all vital for high cell yields. Knowledge of the in vitro growth properties of the cells made it easier to arrive at optimal conditions for microcarrier culture of each cell type.

Animals↗
PubMed1979

The right to strike.

Explore the source record for details and available documents.

Collective Bargaining↗