I . The purpose of this paper is to propose the measurement of scalp hair diameter as a useful index of protein synthesis in the management of cases of malnutrition.2. Observations on scalp hair from ten control infants showed that each hair tapered very gradually towards its free end.3. Observations on scalp hair from twenty-six infants with kwashiorkor showed that each hair narrowed towards the follicle; the effect was statistically significant. 4. After I month's treatment for kwashiorkor, scalp hair thickened towards the follicle and the effect was statistically significant.5 . Serial measurements of the greatest diameter at 0.5 mm intervals along the hair shaft had a main trend which was related to nutritional history.6 . The period of time over which narrowing of the hair shaft took place was calculated from the rate of hair growth and the serial diameter measurements: this time was always longer than the history of kwashiorkor.
Hair samples were obtained from the scalps of 5 infants with kwashiorkor and 5 matched control infants on a balanced diet.The greatest diameters of the hairs were measured in their natural state, ethanol, xylol, water and air. The diameters of the kwashiorkor hairs were 8 to 22% larger in water than in air while the diameters of the control hairs were 5 to 8% larger. This indicates that the stability of the cross links between the polypeptide chains of hair proteins is reduced in kwashiorkor.The mass per unit area of cryostat sections of hair was estimated by electron probe x-ray emission microanalysis. No difference was demonstrable between the density of proteins in kwashiorkor and control hair. It is concluded that the soft texture of kwashiorkor hair is not associated with a reduction in the density of its proteins.
The literature on regeneration in the central nervous system of vertebrates has been reviewed exhaustively by Windle (1955, 1956). Adult fish and urodeles reestablish physiological and anatomical continuity of the spinal cord after it has been completely transected while adult anurans (Piatt & Piatt, 1958) and mammals on the whole do not. In all groups of vertebrates regeneration is more successful in the period of early embryonic development, and becomes less so as development proceeds. Experiments designed to investigate the factors responsible for this change demand an animal in which the difference in the regenerative capacity of embryonic and adult form is marked, and all stages of development are easily accessible for operative procedures. These criteria are satisfied by Anura. For this reason regeneration in the anuran central nervous system merits further investigation. After spinal cord transection in urodele larvae, Piatt (1955) found that the Mauthner axons did not regenerate although other axons around them did.
The incorporation of H3-tyrosine into the protein of the cells in the cortex of rat hair has been investigated by radioautography. In growing hairs, radioactivity is found in the matrix, the upper bulb, and the whole of the keratogenous zone up to the fully keratinized part of the shaft, 10 and 30 minutes after an injection of labelled tyrosine. This is unequivocal evidence of protein synthesis at these sites. There is a very precise relationship between the end of protein synthesis and the hardening of the cortical cells at the top of the keratogenous zone. The way in which the silver grains of the radioautographs are clustered indicates that at 30 minutes after the injection the isotope is distributed more evenly in the matrix and upper bulb than in the top of the keratogenous zone. Possibly this reflects a difference, at these sites, in the cell components engaged in protein synthesis, or in the proteins being synthesized. The fully keratinized and hardened part of the hair was not radioactive at 10 and 30 minutes after the injection of H3-tyrosine. The rate at which the radioactivity moves into this region shows that the hair of rats grows 0.9 mm/24 hours. Comparison of the degree of radioactivity along the growing hair in the 30-minute, 12-hour, and 36-hour materials shows conclusively that protein accumulates in the cortical cells during their keratinization. An injection of a labelled amino acid does not behave as an ideal pulse dose; consequently, the grain density over the hair cortex at 36 hours is 100 per cent larger than would be expected if an ideal pulse dose situation existed.
Observations were made on the epidermis of 10 Zulu infants with kwashiorkor and 5 control infants. The thickness of the kwashiorkor Malpighian layer was less than that of the controls; since no diflerences were apparent between kwashiorkor and control cell volumes, it was concluded that there are changes in the kinetics of cell migration in kwashiorkor.Measurements of junction granules in the basement membrane and spinous cell desmosomes indicate that they should be classified as separate entities.The lengths of kwashiorkor desmosomes were found to be less than the lengths of control desmosomes and could be associated with the fragility of the epidermis in kwashiorkor.The thicknesses of the stratum corneum (9 nm) and its individual cells (2500 A) in kwashiorkor were thinner than those of the controls (25 nm and 8500 A respectively). The protein content of a kwashiorkor infant's epidermis may be one third that of a well fed infant of the same build.
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