Characterisation of cerebroside 3-sulphate dispersions

Galactosyl ceramide 3-sulphate (cerebroside 3-sulphate) was tritiated using [³H]NaBH₄ with PdCl₂ as catalyst. Quantitative purification of the three components of the product was achieved by chromatography on Florisil. Dispersions, prepared by either low energy sonication or by dilution from organic solvent, were compared by controlled pore glass chromatography, ultra-centrifugation and electron microscopy. Both dispersion techniques were shown to form unilamellar vesicles, the average size of vesicles produced by sonication being far larger than those produced by solvent dilution. The diameter of isolated vesicles produced by solvent dilution was in the range 10–80 nm.     

Insect and meat eating among infant and adult baboons (Papio cynocephalus) of Mikumi National Park, Tanzania

It has been suggested that baboon predation upon vertebrates may tend to peak in the dry season because insect food is then less available, and that males obtain animal nutrients primarily from vertebrates whereas other troop members obtain them primarily from invertebrates. The development of meat and insect eating by 22 male and 24 female infants studied for 25 months was compared with that of 18 male and 46 female adults studied for 37 months. Systematic sampling allowed quantitative comparisons between meat and insect eating, infants and adults, and males and females. Infants ate no meat, but their insect eating began early and increased steadily during the first year of life. In comparison with insect foods, meat was a minor ingredient of the adult's diet. Insect eating occurred less during dry than during rainy months, but meat eating was spread across the year. Reliable sex differences in insect eating did not occur. The findings were related to theories offered to explain the attractiveness of animal foods to primates and to the suggestion that a sex difference in predatory inclinations of hominid ancestors may have been a preadaptation underlying the eventual emergence of male hunting and female gathering.     

The definitive identification of the lignans trans-2,3-bis(3-hydroxybenzyl)-gamma-butyrolactone and 2,3-bis(3-hydroxybenzyl)butane-1,4-diol in human and animal urine.

The definitive identification of the first lignans to be found in humans and animals is described. Gas chromatography--mass spectrometry, n.m.r. spectroscopy, i.r. spectroscopy and chemical techniques were employed to establish the structures of two lignans as trans-2,3-bis(3-hydroxybenzyl)-gamma-butyrolactone and 2,3-bis(3-hydroxybenzyl)butane-1,4-diol. Both compounds are essetially racemic. Evidence was also found for several methoxy analogues of these lignans in the vervet monkey.     

Characterization of a potent biotin-conjugated CRF analog and the response of anterior pituitary corticotropes

A biotin-conjugated synthetic corticotropin releasing factor (B-CRF) was prepared and characterized. Its biological activity and binding affinity were compared with that of unlabeled synthetic CRF. Both forms of the releasing factor were equipotent in in vitro studies measuring the release of corticotropin (ACTH) (ED50 = 1 nM). The IC50 in the binding assays was 1.5 nM for CRF and 4 nM for B-CRF. Dual avidin-biotin peroxidase complex stains were then used in pituitary monolayer cultures to visualize receptivity to the releasing factor and to confirm opiocortin storage in the target cells. All corticotropes showed stain for B-CRF. The percentage of cells that were double-labeled for ACTH and CRF increased with the dose of B-CRF during a four hour incubation period. The CRF stain was abolished, however, when an excess of unlabeled CRF was added to compete with B-CRF. The distribution of the B-CRF and ACTH stains varied in the cells with the time of exposure to the analog. These studies show that biotin-conjugate CRF is a potent analog that can be demonstrated cytochemically on cells identified immunocytochemically as corticotropes. It can be used to follow important events associated with CRF stimulation including the rapid internalization of CRF coupled with the mobilization of corticotropin stores and the formation of cellular processes.     

Properties and regulation of high-affinity pituitary receptors for corticotropin-releasing factor

Specific receptors for corticotropin-releasing factor (CRF) were identified in the rat anterior pituitary gland by binding studies with 125I-Tyr-CRF. Binding of the labeled CRF analog to pituitary particles was rapid and temperature-dependent, and reached steady state within 45 min at 22 degrees C. The CRF binding sites were saturable and of high affinity, with dissociation constant (Kd) of 0.76 X 10(-9) M. Pituitary binding of 125I-Tyr-CRF was inhibited by CRF, Tyr-CRF and the active 15-41 fragment of CRF, but not by the inactive 21-41 CRF fragment and unrelated peptides. The binding-inhibition potencies of the CRF peptides were similar to their activities as stimuli of adrenocorticotropic hormone (ACTH) release. The high-affinity CRF sites were markedly reduced in adrenalectomized rats, and this change was reversed by dexamethasone treatment. These data indicate that the high-affinity CRF sites demonstrated in the anterior pituitary are the functional receptors which mediate the stimulatory action of the peptide on ACTH release, and that CRF receptors are down-regulated during increased secretion of the hypothalamic hormone.     

The effect of semicarbazide on the nature and stability of collagen fibrils

Semicarbazide affected both the final width and stability of fibrils reconstituted from solutions of acid-soluble collagen. Fibril width was increased after semicarbazide treatment at pH2.6 and 4.3, whereas after treatment at pH8.9 it decreased. Fibril stability was decreased after semicarbazide treatment at all values of pH and temperature, indicating the inhibition of intermolecular cross-linking. A direct binding of semicarbazide to the alphabeta-unsaturated aldehyde groups in the intramolecular cross-link was demonstrated.