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Biomedical subjects

L Craig

Publications and source records attributed to L Craig.

10 recordsLinked to original sources
PubMed1994

Identification of the membrane-binding domain of rat liver CTP:phosphocholine cytidylyltransferase using chymotrypsin proteolysis.

Limited chymotrypsin proteolysis of CTP:phosphocholine cytidylyltransferase (CT; EC 2.7.7.15) produced several distinct fragments which were mapped to the N terminus of CT using antibodies directed against the N and C terminus and the conserved central domain. A time course of chymotrypsin proteolysis showed a progression in digestion as follows: 42-->39-->35-->30-->28-->26 kDa. The binding of CT and of the chymotrypsin fragments to lipid vesicles was assessed by floatation analysis. The ability of the fragments to bind to activating lipid vesicles correlated with the presence of a putative amphipathic alpha-helix, helix-1, between residues 236 and 293. Fragments lacking this helix could, however, bind to phosphatidylcholine/sphingosine vesicles, which inhibit CT activity, and were capable of dimer formation. The degree of resistance to chymotrypsin degradation increased when CT was bound to the strongly activating lipid vesicles phosphatidylcholine/oleic acid (1:1) and phosphatidylcholine/phosphatidylglycerol (1:1). Conversion of the 39- and 35-kDa fragments, which contain the intact helix-1, to the 30-, 28-, and 26-kDa bands, which lack helix-1, required longer proteolysis times, suggesting that this helical domain is more shielded from solvent upon membrane binding. These results support the theory that CT has a bipartite tertiary structure composed of a globular N-terminal domain and an extended C-terminal domain and that CT interacts with membranes via its putative amphipathic helix which intercalates into the membrane bilayer of activating phospholipids.

Animals↗
PubMed1994

Random peptide libraries.

Over the past year, great strides have been made in the design of peptide libraries, and new approaches have been developed for identifying peptide ligands. The libraries comprise large collections of peptides, ranging from 1 million to 1 billion different sequences, which can be screened using monoclonal and polyclonal antibodies, receptors, enzymes or other target molecules. The power of this technology stems from the chemical diversity of the amino acids coupled with the large number of sequences in a library. As such, peptide libraries may be useful for finding ligands that can serve as leads for pharmaceutical development and other purposes.

Amino Acid Sequence↗
PubMed1985

Changes in blood constituents accompanying exercise in polo horses.

There have been several studies of biochemical changes in horses doing intense exercise such as Thoroughbred and Standardbred racehorses and in horses performing exercise over a long period of time such as endurance horses and three-day eventing horses, but we are not aware of studies with polo horses. Blood samples were taken from 18 polo horses at rest, immediately after playing 2 chukkers of indoor polo, and after a 15 minute rest period. Each horse was studied at 2 different games. The blood samples were analyzed for lactic acid, protein, sodium, potassium, chloride, calcium, phosphorus, HCO-3, PCO2, hemoglobin, packed cell volume, and pH. Samples taken immediately after playing polo had significant increases in lactic acid, protein, sodium, hemoglobin, packed cell volume, and pH, and significant decreases in chloride, calcium, PCO2, and HCO-3. Pulse and respiration were significantly increased. After a 15 minute rest period, there was a significant decrease in potassium. The HCO-3 was lower immediately after playing, but was above the resting value after 15 minutes. It was concluded that the changes after exercise are similar in some aspects to those reported for horses performing intense exercise such as racehorses, and in some aspects to those reported for horses performing prolonged exercise such as three-day event horses and endurance horses. Horses playing indoor polo develop a high plasma lactic acid, but with alkalemia, and could be used as a model to study this condition.

Animals↗
PubMed1980

An evaluation of the 14C-glycocholic acid breath test in the diagnosis of bacterial colonisation of the jejunum.

In order to assess the performance of the 14C-glycocholic acid breath test as an indicator of bacterial colonisation of the jejunum, 145 combined breath tests and jejunal aspirate cultures were carried out on a total of 50 subjects who had an increased probability of being colonised. Ninety-one of the 145 cultures were positive while only 31 of the breath tests were positive. This poor performance of the breath test relative to the aspirate culture can be predicted with reasonable accuracy from known bile deconjugating capabilities of bacteria found in the small intestine.

Bacterial Infections↗
PubMed1975

Leigh's disease: significance of the biochemical changes in brain.

Analysis of five brains from patients with Leigh's disease demonstrates an accumulation of thiamine pyrophosphate and a deficiency of thiamine triphosphate. The enzyme which converts thiamine pyrophosphate to thiamine triphosphate was normally active in two of these brains, suggesting that the inhibitor found in Leigh's disease is probably producing the observed neurochemical changes. Reasons for the histological similarity between Leigh's and Wernicke's diseases are suggested.

Brain↗