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Biomedical subjects

L Kay

Publications and source records attributed to L Kay.

82 records · Page 5Linked to original sources
PubMed1981

The role of synovectomy in the management of recurrent haemarthroses in haemophilia.

Between August 1973 and May 1979, 18 patients suffering from severe haemophilia A underwent synovectomy for recurrent haemarthroses, resistant to medical management. A total of 23 joints (11 knees and 12 elbows) were subjected to operation, five patients undergoing two synovectomies on different joints. Post-operative follow-up period ranged from 12 to 58 months for elbow synovectomy and from 29 to 76 months for knee synovectomy. All patients experienced fewer haemarthroses, the average number of bleeding episodes per joint over a 12 month period being reduced from 19 to 3 for knee joints, and from 24 to 3 for elbow joints. This improvement was apparent in the immediate post-operative year and maintained thereafter. Over the same follow-up period nine of the 11 knee joints were found to have lost an average 42 degrees mobility. Following elbow synovectomy five out of 12 patients lost an average of 28 degrees mobility; six patients gained an average 11 degrees mobility. The post-operative complication rate was high for knee synovectomy, 54% suffering haemorrhage despite haemostatic factor VIII levels. For elbow synovectomy the rate was much lower, 75% of operations being uncomplicated. The average in-patient time for knee operation was 75 d, and for the elbow 19 d. We conclude that synovectomy of the knee joint is to be avoided when other means of reducing bleeding episodes are available, whereas elbow synovectomy retains a useful role in the treatment of recurrent haemarthroses which do not respond to clotting factor prophylaxis.

Adolescent↗
PubMed1977

The echocardiophone: a new means for observing spatial movement of the heart.

The paper describes a new pocket size instrument called the "Cardiophone" for the diagnosis of cardiac dysfunction. It is a continuous wave swept frequency ultrasonic echo-location system which produces dynamic auditory signals corresponding to the positional change of internal structures of the heart. The four valves are relatively easy to locate compared with conventional ECG machines. Preliminary clinical evaluation results are presented indicating the potential of the instrument for the general practitioner.

Echocardiography↗
PubMedDate not supplied

On the regulation of cellular energetics in health and disease.

Very recent experimental data, obtained by using the permeabilized cell technique or tissue homogenates for investigation of the mechanisms of regulation of respiration in the cells in vivo, are shortly summarized. In these studies, surprisingly high values of apparent Km for ADP, exceeding that for isolated mitochondria in vitro by more than order of magnitude, were recorded for heart, slow twitch skeletal muscle, hepatocytes, brain tissue homogenates but not for fast twitch skeletal muscle. Mitochondrial swelling in the hypo-osmotic medium resulted in the sharp decrease of the value of Km for ADP in correlation with the degree of rupture of mitochondrial outer membrane, as determined by the cytochrome c test. Very similar effect was observed when trypsin was used for treatment of skinned fibers, permeabilized cells or homogenates. It is concluded that, in many but not all types of cells, the permeability of the mitochondria outer membrane for ADP is controlled by some cytoplasmic protein factor(s). Since colchicine and taxol were not found to change high values of the apparent Km for ADP, the participation of microtubular system seems to be excluded in this kind of control or respiration but studies of the roles of other cytoskeletal structures seem to be of high interest. In acute ischemia we observed rapid increase of the permeability of the mitochondrial outer membrane for ADP due to mitochondrial swelling and concomitant loss of creatine control of respiration as a result of dissociation of creatine kinase from the inner mitochondrial membrane. The extent of these damages was decreased by use of proper procedures of myocardial protection showing that outer mitochondrial membrane permeability and creatine control of respiration are valuable indices of myocardial preservation. In contrast to acute ischemia, chronic hypoxia seems to improve the cardiac cell energetics as seen from better postischemic recovery of phosphocreatine, and phosphocreatine overshoot after inotropic stimulation. In general, adaptational possibilities and pathophysiological changes in the mitochondrial outer membrane system point to the central role such a system may play in regulation of cellular energetics in vivo.

Adenosine Diphosphate↗
PubMedDate not supplied

Functional coupling as a basic mechanism of feedback regulation of cardiac energy metabolism.

In this review we analyze the concepts and the experimental data on the mechanisms of the regulation of energy metabolism in muscle cells. Muscular energetics is based on the force-length relationship, which in the whole heart is expressed as a Frank-Starling law, by which the alterations of left ventricle diastolic volume change linearly both the cardiac work and oxygen consumption. The second basic characteristics of the heart is the metabolic stability--almost constant levels of high energy phosphates, ATP and phosphocreatine, which are practically independent of the workload and the rate of oxygen consumption, in contrast to the fast-twitch skeletal muscle with no metabolic stability and rapid fatigue. Analysis of the literature shows that an increase in the rate of oxygen consumption by order of magnitude, due to Frank-Starling law, is observed without any significant changes in the intracellular calcium transients. Therefore, parallel activation of contraction and mitochondrial respiration by calcium ions may play only a minor role in regulation of respiration in the cells. The effective regulation of the respiration under the effect of Frank-Starling law and metabolic stability of the heart are explained by the mechanisms of functional coupling within supramolecular complexes in mitochondria, and at the subcellular level within the intracellular energetic units. Such a complex structural and functional organisation of heart energy metabolism can be described quantitatively by mathematical models.

Adenosine Triphosphate↗