Biomedical subjects
Publications and source records attributed to L J Clark.
Pigmented villonodular synovitis commonly occurs in synovial joints of the appendicular skeleton, but rarely affects the synovial joints of the spine. It has both neoplastic and benign features, and the etiology is thought to be posttraumatic. The case of a young man presenting with paraparesis and a large thoracic lesion is reported.
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Relapsing polychondritis is a rare disease which often presents firstly to ear, nose and throat (ENT) departments. Its complications, respiratory, cardiovascular, renal and neurological are life-threatening; thus it is important to recognize the disease and its complications early. Treatment for relapsing polychondritis may have serious side-effects which should be taken into account when managing these patients. We report two young patients with relapsing polychondritis and their treatments; both had severe tracheal stenosis responding in one case to pharmacological and in the other to surgical intervention.
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Carcinoma of the middle ear is a difficult tumour to treat. We present ten cases and discuss staging of these tumours. Our results would suggest that a revised staging system may allow better identification of patients that would benefit from surgery whilst sparing some multilating surgery that offers little to improve their quality or quantity of life.
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We present a prospective controlled trial, comparing methods of analgesia for the relief of discomfort on removing nasal packing, including a general discussion on the considerations for, and methods of, nasal tamponade. On the basis that nasal packing is likely to continue to be used frequently, nitrous oxide (as Entonox) is advocated as a safe and relatively cheap means of pain relief with a statistically significant advantage over papaveretum.
Commercial non-lubricated latex condoms were unpackaged and exposed in an environmental chamber to ozone levels (0.3 ppm) commonly present in urban smog conditions. Deterioration was observed by scanning electron microscopy after 18 hours exposure. Loss of mechanical strength was quantitated by measurement of the air pressures necessary to burst the condom and volumes at burst. After 24 hours exposure to ozone the latex surface was covered with craters and after 48 hours the pressure required to burst the condom was 44% that of control samples. Data suggest the need for study of the effectiveness of lubrication and packaging in protecting condoms from environmental factors which may accelerate deterioration.
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Fusion of normal human, goat, bovine and chicken erythrocytes was investigated using the phosphate-calcium protocol. The relative effects on fusion efficiency of cell shape, membrane deformability, and composition and orientation of phospholipids in the lipid bilayer were ascertained. Exposure of red blood cells to phosphate ions followed by calcium led to cell agglutination at room temperature for all species. Incubation at 37 degrees C for periods up to 2 hours caused hemolysis and membrane-associated protein aggregation followed by fusion in human and chicken erythrocytes but not in bovine or goat red cells. Cell shape may not be a determinant in fusion since bovine, like human erythrocytes, are biconcave but do not fuse with the above protocol. Bovine and goat red blood cells lack phosphatidylcholine in their membranes. Incorporation of phosphatidylcholine into bovine red blood cells, mediated by a specific transfer protein, promoted their fusion. Our results indicate the important role played by phospholipid composition and orientation in red cell membranes for fusion by phosphate and calcium.
An improved method is described for measuring red cell membrane deformability via aspiration into the 0.6 micron pores of Nuclepore filters. Application of this technique to the membranes of echinocytes formed in various ways showed that the method of preparation, not the final shape, determined deformability. Old and young red cells had equally deformable membranes. Membrane deformability was independent of the internal viscosity of cells suspended in media over the range 300-600 mOsm, while between 300 and 100 mOsm the deformability decreased.
Negative charges on the external surface of red cells were visualized by colloidal iron hydroxide labelling of 50% of the membrane area after osmotic hemolysis and glutaraldehyde fixation. Counts were made over randomly selected areas on electron micrographs at 350,000 x magnification. Statistical analyses showed that at the 95% level of confidence there was no significant difference between oxygenated normal (AA) and sickle (SS) cells in either the distribution or the density of negative charges.
The Hospital Survey and Construction Act of 1946, commonly known as the Hill-Burton Act, was intended to improve the supply, distribution and quality of general hospital beds across the United States. Some also saw the program as a means of affecting the supply and distribution of physicians. The strategy used here for evaluating the Hill-Burton program derives in part from the assumptions about health resources supplies on which Hill-Burton policy was found and in part from a model of socioeconomic convergence developed in public policy research on the American states. Major conclusions include 1) Hill-Burton had a major redistributive impact on state bed supplies; 2) physician redistribution lagged far behind progress in bed redistribution; and 3) interstate distribution of physicians appears to have been unaffected by Hill-Burton-associated bed redistribution, a finding contrary to other work in this area.
Saskatoon serviceberry (Amelanchier alnifolia) twigs were administered to cattle in feed rations and by intraruminal dosing to determine the toxicity of the cyanogenic shrub. When chopped twigs were fed as 75% of the diet, cattle exhibited restlessness, shivering, loss of weight, scours and shortness of breath. Low level dosing experiments indicated a rapid turnover of hydrogen cyanide in the rumen. When potential doses were increased to 5 mg hydrogen cyanide/kg (body weight) progressive stages of poisoning developed rapidly, rumen hydrogen cyanide levels were elevated for at least three hours and the increase in heart rate correlated with the rise in blood hydrogen cyanide concentration.
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Honolulu is the host city for the MLA Annual Meeting in 1979. The attractions of Honolulu and Hawaii are recommended to members.