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Biomedical subjects

S George

Publications and source records attributed to S George.

At least 271 records · Page 15Linked to original sources

Purification and characterization of naturally occurring and in vitro induced multiple forms of MM creatine kinase.

MM creatine kinase purified from tissue exists as a single form but upon release into the plasma exhibits three forms which, based on increasing anodal migration on polyacrylamide gel electrophoresis, are referred to as MM1, MM2, and MM3. The three forms were isolated in pure form from plasma in sufficient quantities for biochemical and physiological studies. Chromatofocusing results show that MM1, MM2, and MM3 have distinct isoelectric points of 7.58, 7.43, and 7.30, respectively. Analysis on high pressure liquid chromatography showed MM1 and tissue creatine kinase (MMt) to have identical peptide maps, but MM2 and MM3 were different in at least one amino acid. Tissue MM creatine kinase was converted in vitro to MM2 and MM3 after incubation in plasma. Conversion was unaffected by nonspecific proteases but inhibited by benzoylarginine, epsilon-amino caproic acid, and guanidinoethylmercaptosuccinic acid, specific inhibitors of carboxypeptidase N. Digestion of purified tissue MM creatine kinase with carboxypeptidases N and B produced MM2 and MM3 which were identical with the forms produced in vivo. Hybridization experiments with MM1 plus MM3 produced all three forms, as did tissue MM creatine kinase plus MM2. MM2 was also able to produce all three forms in the experiments. The plasma half-life of tissue MM creatine kinase or MM1 was shown to be about one-half that of MM3. The results suggest that hydrolytic cleavage of a basic amino acid, presumably by carboxypeptidase N, is responsible for conversion of MMt to MM2 and MM3. COOH-terminal amino acid analysis demonstrated the COOH-terminal amino acid of canine and rabbit MM1 to be lysine. Thus, we conclude that cleavage of the COOH-terminal lysine from MMt by serum carboxypeptidase N generates two additional MM creatine kinase isoforms with prolonged plasma clearance rates.

Animals↗

The protein binding of timegadine determined by equilibrium dialysis.

The protein binding of timegadine to albumin, serum, plasma and plasma enriched with the acute phase reactants alpha 1-acid glycoprotein, alpha 1-anti-trypsin and C-reactive protein was determined by equilibrium dialysis. The effects of other analgesic and anti-inflammatories (indomethacin, ketoprofen, paracetamol and sodium salicylate) and other basic drugs (disopyramide, lignocaine, propranolol and quinidine) on the binding of timegadine were also determined. Timegadine binding was concentration-dependent up to 0.5 micrograms/ml, but independent above this level up to 10.0 micrograms/ml, the mean and standard error being 93.8 +/- 0.5%. Albumin accounted for only 32.4% of timegadine bound to plasma. Plasma enrichment with the acute phase reactants led to significant increases in timegadine binding. Simultaneous dialysis with other drugs caused significant decreases in timegadine binding.

Anti-Inflammatory Agents↗

Birth complication reporting: the effect of birth certificate design.

The completeness of reporting of selected birth complications and congenital malformations on the Washington State birth certificate was estimated by comparing the total occurrences reported on birth certificates to the totals reported in hospital records. Two time periods were studied (1977-78 and 1980-81 before and after changes in birth certificate design). The design change (inclusion of a series of check boxes for conditions) was found to provide more complete reporting of birth complications.

Birth Certificates↗

Isolation of West Nile virus from the brains of children who had died of encephalitis.

The isolation of West Nile virus from the brain tissue of three children who died of encephalitis in Mysore and Kolar districts of Karnataka State, India, is reported. This is the first such report from India. The significance of these isolations with reference to the role of West Nile virus in encephalitis in children in southern India is discussed.

Adolescent↗

The influence of food intake on the bioavailability of timegadine, a novel non-steroidal anti-inflammatory drug.

The effects of food ingestion on the absorption of timegadine, a recently synthesised non-steroidal anti-inflammatory drug, was studied in ten healthy volunteers. It was found that food enhanced the absorption of timegadine as shown by increased peak plasma concentrations (Cmax), decreased time taken to achieve these concentrations (tmax), and increased area under the plasma concentration time curve (AUC).

Absorption↗

Dopamine receptor sites and states in human brain.

Of the several dopamine-sensitive sites in the brain, the one that most correlates with psychomotor behaviour is the D2 receptor. This receptor has two states. The D2Hi state is characterized by its nM affinity for dopamine. The D2Lo state is typified by its microM affinity for dopamine. Neuroleptics have the same affinity (50 pM for spiperone) for both states. Guanine nucleotides convert most, if not all, of the D2Hi sites into D2Lo sites. Any D2Hi sites which are insensitive to GTP, if such exist, may be separate D4 sites. In addition to the binding of 3H-spiperone being higher in post-mortem schizophrenic brains, the proportions of the D2 receptor in the D2Hi state appear to be less in preliminary data on the schizophrenic brain.

Brain↗

T cell subpopulations in CLL: methods of T cell enrichment artificially alter proportions of OKT4 and OKT8 positive cells.

There is growing speculation about the meaning of reported imbalances in subpopulations of T lymphocytes in patients with chronic lymphocytic leukaemia (CLL). This study compared two techniques for producing T cell enriched subpopulations from both patients with CLL and normal individuals and the effects of these techniques on relative proportions of OKT4 and OKT8 positive cells. A sheep red cell rosetting technique resulted in significantly larger OKT8 and smaller OKT4 positive populations than did nylon wool column elution. Similar results were obtained in normal individuals. The nylon wool column elution technique produced less distortion of unfractionated OKT4/OKT8 ratios in normals than did the rosetting technique. Studies of T lymphocyte subpopulations should be interpreted with great caution as the methods used to study them can influence the results.

Antibodies, Monoclonal↗