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Biomedical subjects

G Kemp

Publications and source records attributed to G Kemp.

16 recordsLinked to original sources
PubMed1992

Proteolysis is a key process in virus replication.

Proteases were amongst the first enzymes to be isolated and crystallized, and the discovery of their existence in viruses and the realization of the vital role they play has given a new lease of life to one of the oldest topics in biochemistry. Already we have seen the discovery of new variations on well-studied reaction mechanisms and there is the promise of others to come that may be totally novel. When this is allied to the prospect of developing the knowledge which is beginning to accrue into a much needed antiviral therapy, it is clear that viral proteases and their key role in viral replication will be an increasing focus of attention for some time to come.

Animals↗
PubMed1979

The presence of a Ca2+ bridge within the gamma chain of human fibrinogen.

The presence of Ca2+ increased the mobility of fragment D, and the gamma chain from fibrinogen on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate, suggesting that a Ca2+ was associated with these fibrinogen derivatives. The mobilities of the constituent chains from fragment D produced under various conditions, indicate that Ca2+ bound to fibrinogen form an intrachain bridge towards the C-terminus of each gamma chain.

Binding Sites↗
PubMed1978

Diuretics.

Explore the source record for details and available documents.

Benzothiadiazines↗
PubMed1976

Bleeding disorder with abnormal wound healing, acid-soluble clots and normal factor XIII.

An unusual bleeding disorder clinically resembling factor XIII deficiency is presented. The only detectable coagulation abnormality was rapid clot dissolution in 1% monochloroacetic acid. This abnormality was ascribed to the sustained increase of a pepsin-like plasma protease which is activated at low pH. Asystematic search for similar phenomena revealed that massive blood transfusion may also enhance plasma-clot solubility in acid, possibly by release of a red cell protease. We conclude that the acid clot solubility test is not a specific indicator of factor XIII deficiency, but this simple assay is recommended for further studies of acid plasma protease activity. The diagnostic relevance and pathophysiologic importance of increased pepsin-like activity in plasma remain to be elucidated.

Acetates↗
PubMed1976

Hypoxanthine excretion during preservation of rabbit kidneys for transplantation. An assessment of the ischaemic damage.

The loss of 5'-adenine nucleotides from kidney tissue subjected to acute ischaemia can be indirectly estimated by washing out the end product of catabolism, hypoxanthine, from the ischaemic tissue to the perfusate. As a correlation has previously been demonstrated between the duration of the previous normothermic ischaemia and the washout of hypoxanthine during preservation, hypoxanthine has been studied as a prospective measurement of ischaemic renal damage, by transplantation of rabbit kidneys. The results were compared to the already established parameters L-lactate and lactate dehydrogenase. Different ischaemic traumata and methods of preservation have been employed in order to determine the relationship of these parameters to the ischaemic kidney damage as evaluated by the functional regeneration of the grafts after autotransplantation. The wash-out of hypoxanthine was found to be correlated to such a degree to the reversibility of the ischaemic cell degeneration that a certain in vitro exclusion of the irreversibly damaged kidney grafts was possible. It is concluded that hypoxanthine can function as a reliable and sensitive measurement for the in vitro establishment of the ischaemic kidney parenchymal damage, and that it can be employed clinically with advantage.

Animals↗
PubMed1975

Plasmic degradation of human fibrinogen. III. Molecular model of the plasmin-resistant disulfide knot in monomeric fragment D.

A mixture of fragments D, derived from fibrinogen by plasmic degradation, was S-reduced and carboxymethylated. Individual chains were separated by gel filtration on Sephadex G-100 and characterized by peptide mapping, N-terminal amino acid analysis, polyacrylamide electrophoresis in sodium dodecyl sulfate, and amino acid composition. It was demonstrated that all D species contain the same alpha- and beta-chain remnants, having mol. wts of 10 000 and 45 000, respectively. Their heterogeneity was shown to be caused by the gradual degradation of the gamma-chain at its C-terminal end. Denatured fragment D was further degraded with plasmin in the presence of 2 M urea. One beta- (mol. wt 17 000) and two gamma-fragments (mol. wts 5000 and 6000) were split from fragment D, in addition to non-characterized small peptides, leaving behind a plasmin-resistant core, designated as fragment d. Fragment d was in turn reduced and carboxymethylated, and the resulting constituent chains were isolated by chromatography on carboxymethyl-cellulose and Sephadex G-100. The reduced alpha-, beta- and gamma-chain remnants of fragment d were found to have been derived from the N-terminal portion of fragment D and have estimated mol. wts of 9000, 24 000 and 13 000, respectively. A tentative scheme for the conversion of an early fragment D into the core fragment d is proposed. Our results conclusively support the model of asymmetric degradation of fibrinogen, according to which 2 mol of monomeric fragment D are produced from 1 mol of fibrinogen.

Amino Acid Sequence↗
PubMed1975

Surface properties of phorbol esters and their interaction with lipid monolayers and bilayers.

The potent tumor-promoting agent 12-O-tetradecanoylphorbol-13-acetate (TPA) is surface active and was found to occupy a limiting area of 62 sq A/molecule in monolayers at the air-water interface. The interfacial tension of aqueous TPA solutions is decreased by increasing the bulk-phase TPA concentrations up to 2 x 10(-6) M,beyond which no further decreases were observed. This concentration is in agreement with the apparent solubility limit previously obtained. The apparent aqueous solubility limit of the more hydrophobic phorbol-didecanoate is 5 x 10(-8) M. Interaction of TPA with egg phosphatidylcholine monolayers at the air-water interface was shown by an increase in the surface pressure of the monolayer from 22 dynes/cm, initial film pressure, to 34 dynes/cm 90 min after introduction of TPA into the aqueous subphase. It was shown by gel filtration chromatography that a similar phorbol derivative, tritiated phorbol-didecanoate, binds to phospholipid vesicles. Differential scanning calorimetry also indicated that the addition of either TPA or an inactive stereoisomer, 4-alpha-phorbol-didecanoate, to phospholipid bilayers results in a marked reduction of the enthalphy of the minor transition of dipalmitoylphosphatidylcholine liposomes. Several fluorescence polarization probes for membrane fluidity indicate that TPA does not affect this membrane parameter. Further, the presence of TPA induces no measurable change in the cation permeability of phospholipid vesicles, the conductance of planar bilayer membranes, or the electrophoretic mobility of negatively charged liposomes. The lack of a specific effect with bilayers alone, combined with the documented physiological effects at low TPA concentrations, point to the possibility of a specific membrane component as the receptor for TPA at the plasma membrane.

Binding Sites↗