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Biomedical subjects

H L James

Publications and source records attributed to H L James.

54 records · Page 3Linked to original sources
PubMed1978

Ventriculoperitoneal (VP) shunt migration causing an acute scrotum: a case report of Doppler evaluation.

The diagnosis and management of a scrotal complication of a ventriculoperitoneal shunt simulating testicular torsion in a neonate is outlined. Radiologic evaluation determined the location of the shunt tube and adequate blood flow to the testicle was confirmed by use of the Doppler stethoscope, allowing for definitive therapy by extraperitoneal shortening of the shunt catheter. Surgery to the scrotum was, thus, avoided.

Cerebrospinal Fluid Shunts↗
PubMed1978

Mechanism of inhibition of porcine elastase by human alpha-1-antitrypsin.

The interaction of the human plasma protein, alpha-1-antitrypsin, with porcine pancreatic elastase was studied by isolating and characterizing their reaction products. Native alpha-1-antitrypsin has a mass ratio (Mr) of 54,000, an amino-terminal glx, and a carboxy-terminal lys residue. The elastase used has an Mr of 26,400 and an amino-terminal val residue. When the two proteins are combined at inhibitor excess, two major products result. One of the products is a complex of the enzyme and inhibitor with amino-terminal ser and val residues, which indicates that a peptide has been removed from the amino-terminal end of the inhibitor. The second product is a modified form of alpha-1-antitrypsin with an Mr of 51,300, an aminoterminal glx residue and a carboxy-terminal thr-leu dipeptide. It has no inhibitory activity against elastase. The components of the isolated complex can be split at high pH in the presence of diisopropyl fluorophosphate, which results in a catalytically inactive enzyme with the same Mr and amino-terminal residue as the native enzyme, and a large fragment of alpha-1-antitrypsin (alpha-1-antitrypsin(*)). This fragment has an Mr of 50,100, an amino-terminal ser residue and a carboxy-terminal thr-leu dipeptide. Based on these data, the following hypothesis is proposed. Elastase can attack alpha-1-antitrypsin at either of two major sites. If it attacks first at the carboxy side of the thr-leu dipeptide, located in the carboxy-terminal portion of the inhibitor, the alpha-1-antitrypsin is cleaved into two fragments with loss of inhibitory activity and absence of complex formation. If, however, the elastase first attacks an x-ser bond near the amino-terminal end of the inhibitor, the elastase then reacts with alpha-1-antitrypsin at the same leu moiety to form a stable complex with complete inhibition of the enzyme.

Amino Acid Sequence↗
PubMed1977

Separation of isoacceptor cysteine transfer ribonucleic acids of bakers' yeasts.

Isoacceptor species of certain amino acid-specific transfer ribonucleic acids (tRNAs) were fractionated by gel permeation chromatography using Sephadex G-100. The separation is attributed to the 20% ethanol-1% NaCl solvent and to the characteristics of Sephadex. Isoacceptor tRNAs specific for cysteine, arginine, phenylalanine, and histidine were recovered from commercial tRNA of yeast by this method. Highly purified cysteine-specific tRNA, obtained by a method which would not be expected to separate isoacceptor molecules when fractionated by this procedure, was shown to contain two cysteine isoacceptor tRNAs.

Amino Acyl-tRNA Synthetases↗
PubMed1976

The interaction of alpha-1-antitrypsin with soluble and sepharose-bound elastase.

The products resulting from the interaction of alpha-1-antitrypsin with elastase were examined with polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate, and by affinity chromatography. Five products of the reaction can be identified by polyacrylamide disc gel electrophoresis. Two products are complexes between alpha-1-antitrypsin and elastase (73 800 and 58 300 daltons). Two additional products are identical to fragments of alpha-1-antitrypsin which can be washed from a column of Sepharose-bound elastase immediately after alpha-1-antitrypsin is applied to the column. The larger component about 50 000 daltons, reacts with antiserum to alpha-1-antitrypsin, and does not inhibit enzymes. Together, these two products have an amino acid analysis similar to alpha-1-antitrypsin. These two fragments are probably hydrolytic products of the interaction of elastase with alpha-1-antitrypsin which is biologically inactive. The fifth product is probably a fragment of alpha-1-antitrypsin missing from the low molecular weight complex. The components of the complexes can be separated from each other by a mild nucleophilic attack. Small quantities of alpha-1-antitrypsin can be displaced from the elastase affinity column by phenyl methane sulfonyl fluoride. In conclusion, porcine pancreatic elastase forms two complexes with alpha-1-antitrypsin. One or both complexes can be split by alkali.

Amino Acid Sequence↗
PubMed1975

Platelet fibrinogen. Identity and initial observations on the mode of its degradation by plasmin.

Fibrinogen has been purified from human platelets. Platelet fibrinogen exhibits a characteristic pattern in agar gel immunoelectrophoresis different from that of plasma fibrinogen. Stepwise plasmin degradation has been used in further elucidation of the molecular properties of the platelet protein. Examination of comparative digests by immunologic and gel electrophoretic methods has revealed that (1) the platelet protein is more resistant to plasmin degradation, (2) the plasmin-produced fragments of platelet fibrinogen differ consistently from those of its plasma counterpart, and (3) platelet fibrinogen is different from fragment X of plasma fibrinogen. It is suggested that platelet fibrinogen may contribute to the stability of the thrombus.

Animals↗
PubMed1975

Isolation and properties of a low molecular weight antiplasmin of human blood platelets and serum.

A low molecular weight antiplasmin has been detected in human blood platelets. The antiplasmin is dialysable and a similar material is present in normal plasma. A simple method for rapid isolation of the antiplasmin based on ultrafiltration is described. The inhibition of plasmin by these materials under different conditions has been studied. In the ultracentrifuge, both antiplasmins showed a single broad peak with an approximate sedimentation coefficient of 0.5S. Paper chromatography and paper electrophoresis indicated the isolated material to be heterogeneous. The individual components were isolated by paper chromatography and the antiplasmin activity was measured by the fibrin plate method. Preliminary studies on the fraction with maximal antiplasmin activity suggest that the inhibitory effect might be due to enzyme-inhibitor complex formation. Based on the present data, it is concluded that the platelet antiplasmin and the serum antiplasmin are very similar. This antiplasmin material may be useful in fibrinolytic therapy.

Antibodies↗