Two hundred seventy-five unprocessed, viable homograft ("homovital") aortic valves were used for aortic valve replacement in patients aged 1.5 to 79 years (mean 45.8 +/- 19 years) with maximum follow-up of a 14-year period (mean 4.8 years). Ninety-two percent (252 patients) had New York Heart Association class III or IV functional status before operation and 25 underwent emergency operation. Valves were harvested under sterile conditions and kept in nutrient medium 199. Freehand (subcoronary) technique was used in 147 patients and freestanding root replacement was used in 128. Cumulative survival rates for the whole group were 92% +/- 2% at 5 years and 85% +/- 3% at 10 years, as compared with 96% +/- 2% and 94% +/- 4%, respectively, for the 98 patients who underwent isolated root replacement. Multivariate analysis determined that root replacement with associated procedures and operation for prosthetic endocarditis were risk factors for death, whereas previous xenograft valve, operation for endocarditis, and operation for aortic regurgitation were risk factors for reoperation. Actuarial rates for freedom from degenerative valve failure diagnosed at operation, by postmortem examination, or by routine echocardiography were 94% +/- 2% at 5 years and 89% +/- 3% at 10 years. Recipient age younger than 30 years and previous xenograft valve were risk factors for late degeneration. We conclude that homovital valves demonstrate good durability, particularly in patients older than 30 years, who had a 10-year freedom from degeneration rate of 97%.

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Beneficial results obtained with sulphamezathine (sulphadimethylpyrimidine) and sulphadiazine (sulphapyrimidine) in the treatment of caecal coccidiosis in chickens have been reported by Horton-Smith and Taylor (1942, 1945, who found the mortality among treated chicks to be reduced by 50 to 73 per cent of that among untreated controls in induced epidemics. Hawkins (1943) also obtained satisfactory results when a saturated sulphamezathine solution was substituted for drinking-water 98 hours after infection of chicks. Ripsom and Herrick (1945) found sulphadiazine to be effective when administered in the food, and Swales (1944) found that both sulphamezathine and sulphamerazine (sulphamethylpyrimidine) had a definite curative effect upon established infections even up to the time when intestinal haemorrhage appeared.Although good results were obtained in the treatment of caecal coccidiosis in chickens by dosing with sulphamezathine incorporated in the food and as a saturated solution in drinking-water, neither of these methods of dosing was perfect. It is difficult in practice to obtain a completely uniform mixture of a small amount of drug with dry food. The low solubility of the drug makes the preparation of saturated solutions of sulphamezathine from the powder troublesome, and such solutions are apt to vary in strength according to the hardness or softness of the water used and the method of preparing the solution. Sulphapyrazine and all the sulphapyrimidine derivatives are more soluble in hard water than in distilled or soft water because the calcium salts are more soluble than the free drugs.

cases the sulphur atoms permit the synthesis of unique molecular types, but it is probably the molecule as a whole and not some special attribute of the sulphur atoms which is responsible for the biological effect. SUMMARY A series of xanthic, dithiocarbamic, thiocyanic and isothiocyanic acid derivatives, together with some oxygen analogues and benzthiazole derivatives, have been prepared and their relative fungistatic activities recorded. In many of the compounds the sulphur atoms can be replaced by oxygen without marked loss of fungistatic power. The ldwer xanthates and certain substituted arylisothiocyanates have very high fungistatic activities. The authors are indebted to several colleagues for the preparation of certain compounds, for helpful discussions and also for the carrying out of the biological testing.