Two polypeptide chain constituents of the major protein of the cornified layer of newborn rat epidermis.

The insoluble component of stratum corneum of rat epidermis yields two major bands after extraction with 8 M urea-mercaptoethanol-dithiothreitol. The ratio of these two bands is about 1:1 in terms of protein stain intensity and S-[14C]carboxymethyl label. Both polypeptides were purified to homogeneity by DE-52-cellulose, sodium dodecyl sulfate hydroxylapatite C column chromatography, and preparative DodSO4-polyacrylamide gel electrophoresis. The heavier polypeptide contains 30% alpha helix and the lighter contains 27% alpha helix as determined by circular dichroism studies. Both are sensitive to Pronase and resistant to trypsin, collagenase, and elastase. The lighter chain is stable to pepsin but the heavier can be partially degraded to a smaller polypeptide with a molecular weight similar to that of light chain. Amino acid analysis shows that the light chain contains 12 more tyrosine residues than does the heavy chain, suggesting that the light chain is not generated from the heavy chain. However, the two chains may have a common peptide region. Antiserum prepared against the heavier polypeptide can be completely absorbed by purified lighter polypeptide and vice versa indicating that both chains have some common antigenic determinants. Antibody against either chain can cross-react with the stratum corneum and keratohyalin granules in the epidermis of newborn rat as indicated by fluorescent microscopic observation. Similarly, this antibody also cross-reacts with the cell surface or the contents of spinous and granular cells, and very weakly with basal cells, indicating that the two proteins may be present in the lower strata as well as the stratum corneum.     

Effects of hypophysectomy and acute growth hormone treatment upon glucose metabolism in adipose tissues and isolated adipocytes of rats.

Glucose oxidation and incorporation into lipid were measured in epididymal adipose tissues and isolated adipose cells of normal and hypophysectomized rats in an effort to determine whether the acute hypoglycemic effect of a systemic growth hormone (GH) injection was related to alterations in the glucose metabolism of adipose tissue. The rats were fed rat chow or a high sucrose diet and received 100 mug GH intraperitoneally 30 minutes or three and one-half hours before sacrifice. Hypophysectomized rats showed a lower plasma glucose as compared with normal rats on both diets. Thirty minutes after a GH injection there was a further decrease of the plasma glucose which, however, was not present in those rats receiving GH three and one-half hours before sacrifice. Adipose tissues from hypophysectomized rats fed the high sucrose diet showed a blunted insulin sensitivity as compared with normal rats on a similar diet. The insulin sensitivity of these tissues was further decreased 30 minutes after a GH injection. Basal glucose metabolism of isolated adipocytes from hypophysectomized rats, as compared with normal rats, was depressed if they were fed rat chow, was at normal levels if they were fed the high sucrose diet and was increased if they were fed the sucrose diet and received triiodothyronine and cortisone supplements. No manipulations of diet or hormonal treatments made the isolated adipocyte from hypophysectomized rats sensitive to insulin either 30 minutes or three and one-half hours after a GH injection. Since basal glucose utilization is not enhanced by GH injection and both the blunted insulin sensitivity of adipose tissue and the absent insulin sensitivity of adipopocytes would be expected to produce hyperglycemia rather than hypoglycemia, it is concluded that immediate systemic effects of a GH injection on carbohydrate metabolism are not related to changes in glucose metabolism of the peripheral adipose tissues.     

Postpartum,hormonal, and nonhormonal induction of maternal behavior in rats: Effects on T-maze retrieval of pups

It is known that the home-cage maternal behavior of rats which become maternal after daily pup exposure (sensitization) is almost indistinguishable from that of lactating mothers, but that sensitized and lactating rats can be distinguished by their pup-retrieval performance in a T-maze extension of the home cage. The present study explored this difference further. Postpartum mothers which could not suckle due to prior nipple removal (thelectomy) retrieved as well, if not better, than intact controls in the T-maze. Hormonal induction of maternal behavior (in ? 3 days) was carried out by hysterectomy-ovariectomy plus 100 μg/kg estradiol benzoate; the performance of these females was similar to that of the postpartum groups. In contrast, only a small percentage of the sensitized mothers retrieved in the T-maze, whether the latency to onset of their maternal behavior was long (4–10 days) or short (? 3 days). Thus, hormonal factors associated with pregnancy and/or parturition, but not suckling stimulation, may facilitate T-maze retrieval of pups. The possible ethological significance of the T-maze test as a measure of maternal responsiveness is discussed.     

Caffeine-modulated acetylcholine sensitivity in denervated rat and diseased human muscle.

Surgically denervated muscle exhibits increased sensitivity to acetylcholine and caffeine, and the acetylcholine contracture subsequent to preincubation with caffeine is greatly enhanced. The potentiation of the acetylcholine contracture derives, at least in part, from the direct action of caffeine on the muscle membrane resulting in an augmented and prolonged depolarization. The extent of potentiation depends on the duration of exposure to caffeine, is inhibited by increased extracellular calcium and is not present when cyclic AMP is substituted for caffeine.Biopsied human intercostal muscle shows high acetylcholine sensitivity in myotonic muscular dystrophy and motor neuron disease when compared to normal human or Duchenne dystrophic muscle. We suggest that myotonic dystrophy and motor neuron disease resemble surgical denervation more than Duchenne dystrophy does, and that in the former two diseases, as in denervated muscle, the acetylcholine sensitivity is increased with a concomitant abnormality in calcium-receptor interaction.     

A simple model for early morphogenesis

Despite the large amount of knowledge which continues to accumulate about early developmental events, very little is known about the processes which control them. Part of the problem may lie in that workers applying different approaches and techniques have different points of view and appear to be reluctant to read each others' literature. My aim in this paper is not to give a generative, formal model for early development, but rather to suggest several connecting strands between the physiological, biochemical, cell biological and experimental embryological approaches which may stimulate new research in fields between those already exploited.     

New bovine adrenal medullary peptide and its precursor

We have isolated a previously unknown peptide and its precursor from bovine adrenal medullary chromaffin granules. The peptide sequence is Leu-Pro-Val-Asn-Ser-Pro-Met-Asn-Lys-Gly-Asn-Glu-Val-Met-Lys. The peptide is cleaved from the precursor at a Lys site. The sequence shows no homology to any known protein in the largest sequence data bank available.     

Infective Factors in Exacerbations of Bronchitis and Asthma

Infections of the respiratory tract were studied in a group of families each containing a patient with chronic bronchitis or with asthma. A wide variety of infective agents may be associated with exacerbations in susceptible subjects, but the types of organism to which patients are most at risk differ according to the family structure. Exacerbations in the susceptible subject are more likely to be related to viral infections when the family contains children than when it does not.Two patients with asthma experienced frequent respiratory infections, many of which provoked attacks of asthma.