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Biomedical subjects

G Venn

Publications and source records attributed to G Venn.

25 records · Page 2Linked to original sources
PubMed1984

Elective femoro-femoral bypass for operations on the heart and great vessels.

Femoro-femoral bypass with "circulatory arrest" is no longer used in routine cardiac operations. Its use today is normally limited to operations wherein access to the arch of the aorta is required or the thoracic aorta is to be temporarily occluded. We have recently encountered three patients presenting with complications of previous operations. In all three, the use of this technique allowed us to approach the defect safely.

Adolescent↗
PubMed1983

Biosynthesis and metabolism in vivo of intervertebral-disc proteoglycans in the mouse.

The synthesis and turnover in vivo of 35S-labelled proteoglycans in mouse cervical, thoracic and lumbar intervertebral discs, and in costal cartilage, was investigated after intraperitoneal injection of [35S]sulphate. Intervertebral discs and costal cartilage synthesize similar amounts of 35S-labelled proteoglycans per microgram of DNA. Discs and cartilage all synthesize a major proteoglycan species (approx. 85%) of large hydrodynamic size and a minor species (approx. 15%) of small size. Both proteoglycans carry chondroitin sulphate chains. Keratan sulphate was not found associated with either species. The total 35S-labelled proteoglycan pool had a metabolic half-life (t1/2) of 10-12 days in discs, and 17 days in cartilage. The extractable major and minor species turned over at similar rates. Those proteoglycans left in the tissue after 29 days turn over very slowly. Approx. 50% of the major 35S-labelled proteoglycan species formed mixed aggregates with hyaluronic acid and rat chondrosarcoma proteoglycan. The ability to form aggregates did not decrease up to 45 days after synthesis. Of the heterogeneous population of proteoglycans comprising the major species, those remaining in the tissue 9 days after synthesis were of smaller average hydrodynamic size and had shorter chondroitin sulphate side chains than the average size at the time of synthesis. With increasing time after synthesis, proteoglycans were less readily extracted from the tissue by 4.0 M-guanidinium chloride than at the time of synthesis.

Animals↗
PubMed1983

Characterisation of collagen from normal and scoliotic human spinal ligament.

Acid-soluble and pepsin-soluble collagens have been isolated from spinal ligaments of normal and scoliotic individuals. Polyacrylamide gel electrophoresis of native and cyanogen bromide-treated collagens, and amino acid analysis, showed that the ligament collagen is almost all of the Type I variety with only trace amounts of Type III present. There was no evidence for abnormal ratios of collagen alpha-chains, or underhydroxylation of proline and lysine in the scoliotic ligament. These results indicate that collagen biochemistry is normal with respect to type, post-translational modification and cross-linking in spinal ligaments of patients with idiopathic scoliosis. Elastin and proteoglycan were only minor components of the ligaments. The nature of the non-collagenous part of the ligament is unknown, although it contains some proteins with a hydrophobic nature.

Amino Acids↗
PubMed1983

Is the undeniably palpable liver ever 'normal'?

A study of whether the lower border of the normal liver, if it extended below the costal margin, could be reliably identified by clinical examination was undertaken in 42 patients in whom there was no clinical, biochemical or scintographic evidence of liver disease. Two clinical observers independently agreed that in 10 of these patients the liver extended infracostally. However, scintiscanning demonstrated that 30 patients had livers extending below the costal margin and that 2 of the 10 livers clinically identified did not in fact lie infracostally. Thus whilst the normal liver commonly extended below the costal margin, recognition of this extension by clinical methods occurred no more frequently than would be expected by chance. It is concluded that the confident clinical finding of a liver projecting below the costal margin should suggest that the organ is abnormal.

Adult↗
PubMedDate not supplied

Paraprosthetic leak: a complication of cardiac valve replacement.

Paraprosthetic leak (PPL) is a rare but potentially serious complication of cardiac valve replacement. Between 1974 and 1988, 1175 prosthetic valves were implanted in 1026 patients by one cardiac surgeon at St. Thomas' Hospital, London. Of these 539 (52.5%) were aortic (AVR), 334 (32.6%) mitral (MVR), 7 (0.7%) tricuspid, and 144 (14%) AV and MV double valve replacements (DVR). There were only 2 triple valve replacements. The prosthetic valves implanted were the Starr-Edwards (7%), Bjork Shiley (11.8%), Lillehei-Kaster (23%), Carpentier-Edwards bioprosthesis (35.2%), Duromedics bileaflet (16.4%) and a variety of other mechanical and bioprosthetic valves (6.6%). Over the 15 year period there were a total of 82 (7%) valve failures of which PPL was diagnosed in 29 (2.5%) valves in 24 patients. Presenting features included cardiac decompensation in 72%, bacterial endocarditis in 12% and haemolytic anaemia in 12%. One patient (4%) had no symptoms. Nineteen patients underwent re-operation. Median time to re-operation was 15 months (range 1-65 months) with a re-operative mortality of 22%. Clinical evidence of prosthetic valve infection was found in 79% of MVR and 67% of AVR. A heavily calcified aortic annulus, found in 47% of patients, may also have contributed to PPL after AVR.

Aortic Valve↗
PubMedDate not supplied

Solubility of spinal ligament collagen in idiopathic and secondary scoliosis.

Supraspinous and interspinous ligaments from patients with infantile and adolescent idiopathic scoliosis and from patients with secondary scoliosis were investigated for collagen content and cross-linking. No differences were demonstrated in the collagen content of ligaments from the idiopathic and secondary scoliosis groups. Collagen solubility studies were used to test for cross-linking defects. Similar amounts of neutral salt-soluble and acetic acid-soluble collagen were extracted from the ligaments of all diagnostic groups. Investigation of the normally insoluble collagen pool extracted from the ligaments of different diagnostic groups after "lyotropic relaxation" revealed no differences in the amount of collagen extracted or in its stability to alkaline denaturation. Control experiments using rat skin collagen showed that the lyotropic procedure solubilized undegraded alpha- and beta-polypeptide chains from the tissue. Reports from other laboratories have suggested the presence of a collagen defect in the skin of patients with adolescent idiopathic scoliosis. The results of the present investigation show that it is unlikely that a generalized defect of collagen cross-linking, or a specific defect of ligament collagen cross-linking, occurs in either infantile or adolescent idiopathic scoliosis.

Adolescent↗