Hypoxanthine phosphoribosyltransferase activity in tissues and hypoxanthine concentrations in plasma and CSF of the horse in comparison with other species

1. Plasma hypoxanthine and xanthine concentrations are very low in the horse and low in rat, mouse and greyhound compared to concentrations in beagles, man, sheep and rabbit. 2. Activities in erythrocytes of the main enzyme metabolizing hypoxanthine, hypoxanthine phosphori-bosyltransferase, show a similar pattern (Tax et al., 1976, Comp. Biochem. Physiol. 54B, 209-212); thus low activities have been found where plasma concentrations were low. 3. Hypoxanthine phosphoribosyltransferase activities in horse tissue other than erythrocytes are similar to those in man and rabbit with high activities in brain; this enzyme may therefore be functionally important in equine brain.     

The inheritance of skeletal muscle fibre composition in mice

Two inbred strains of mice C3H/HE and SWR, and generations produced by intercrossing, were studied to investigate the effect of heredity on muscle composition. The data were found to be consistent with a polygenic mode of inheritance. No simple effect of sex-linkage or maternal influence was evident. The heritability of fibre type percentage total fibre number and the relative size of Type I and Type II fibres were highly significant. Principal component analysis yielded a "genetic" vector which accounted for 57% of the variation in muscle fibre composition. Patterns of covariance of fibre type percentage, total fibre number and relative sizes of Type I and Type II fibres showed a single correlated response.     

Mutants of Yeast Sensitive to Ultraviolet Light

Six uvr mutants of Saccharomyces cerevisiae with hypersensitivity to ultraviolet (UV) light were isolated after mutagen treatment with ethylmethanesulfonate. UV sensitivity ranges from moderate to extreme, and four of the mutants are also sensitive to nitrous acid. Ranking in terms of UV sensitivity does not parallel ranking in terms of nitrous acid sensitivity. Homozygous diploid mutant strains are somewhat less sensitive than the corresponding haploids. All mutations are recessive. None of the mutants is sensitive to gamma rays, and each shows photoreactivation after UV radiation. Complementation tests and tetrad analysis indicate that each strain represents mutation in a different gene. Two of the uvr genes are linked, and two others are centromere-linked.     

Economic Aspects of “Whiplash” Injury

The term “whiplash,” used to describe a neck injury received in an automobile accident, has no foundation in medical science to support the complaints of persons suing for damages. The term is gaining unwarranted popularity as a term describing an injury, even though there are no clinical or pathological findings to support it.“Whiplash” cases today account for an estimated 30 per cent of all injuries in automobile accidents. Direct compensation for damages paid to persons injured in automobile accidents in the United States in 1961 amounted to approximately one billion, seven hundred million dollars. It has been estimated that five hundred and eighty million dollars of that amount was paid in compensation on allegation of neck injuries.     

Assay of the mycobactins by measurement of the growth of Mycobacterium johnei

A method is described for the assay of mycobactin P and T by turbidimetric measurement of the growth of Mycobacterium johnei. The assay agrees satisfactorily with spectroscopic determination of the iron complexes. The growth curves with mycobactins P and T differ somewhat in form. An approximate ratio of activities has been determined.     

Effect of Growth Stage and Initial Inoculum Level on Leaf Rust Development and Yield Loss Caused by Puccinia recondita f. sp. tritici

The effects of the combinations of leaf rust inoculation at different growth stages and initial inoculum levels on leaf rust development and yield of winter wheat cultivars, McNair 1003 and Coker 762 were evaluated. Disease onset stage and initial inoculum level affected the rate of leaf rust development and shape of the disease progress curves in both cultivars. Epidemics with common onset stages and different initial inoculum levels differed in area under the disease progress curve (AUDPC). Leaf rust epidemics initiated at Feeke's growth stages 5, 7, and 10 reduced yield in both cultivars. Leaf rust epidemics initiated early with high inoculum levels had the greatest deleterious effect on yield. Maximum losses due to leaf rust were 30–40 %. Yield loss was directly related to AUDPC when the AUDPC varied from 500 to 1700 in McNair 1003 and from 250 to 1700 in Coker 762. Yield reduction was mainly due to reduction in grain weight.