Biomedical subjects
Publications and source records attributed to H Yajima.
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Synthetic human calcitonin gene-related peptide (CGRP) was examined for the action on the bone in vitro. Human CGRP inhibited bone resorption stimulated by both human parathyroid hormone and basal. The mode of inhibitory action of human CGRP seemed to be similar to that of calcitonin and the relative potency of human CGRP to inhibit bone resorption is one five-hundredth of that of human calcitonin. Thus, a novel pharmacological action of CGRP was demonstrated.
Studies were conducted in dogs to determine the effect of synthetic chicken and porcine vasoactive intestinal peptide on blood flow and exocrine secretion of the pancreas and on systemic arterial pressure. The stimulatory effect of synthetic chicken vasoactive intestinal peptide on blood flow and exocrine secretion of the pancreas was almost similar to that observed after synthetic porcine vasoactive intestinal peptide stimulation, whereas, synthetic chicken vasoactive intestinal peptide retained only approximately two thirds of the potency of synthetic porcine vasoactive intestinal peptide in its effect on lowering systemic arterial pressure. This study suggests that an increase in exocrine pancreatic secretion may be related to an increase in pancreatic blood flow in response to vasoactive intestinal peptide. This study leads us to speculate that total amounts of splanchnic organ blood flow increased in response to porcine vasoactive intestinal peptide are much more greater than those after chicken vasoactive intestinal peptide stimulation, although we cannot exclude the possibility that porcine vasoactive intestinal peptide may be much more potent in its effect on vasodilations in peripheral systemic vessels in comparison with chicken vasoactive intestinal peptide.
Thirteen analogues of the natural macrophage activator peptide tuftsin, ten of which are novel, were synthesized with the aim of exploring the relation between their biological potency and their capacity to attach specifically to cellular tuftsin's receptors. The analogues representing modifications and chain extensions at various parts of the parent tuftsin molecule can be classified as N-terminal analogues, C-terminal analogues, "within-chain" derivatives, or dimers of tuftsin and retrotuftsin. The various synthetic routes employed to prepare the analogues are described. A direct correlation was found between the ability of analogues to inhibit [3H-Arg4]tuftsin specific binding to mice peritoneal macrophages and their capacity to enhance phagocytosis or to inhibit tuftsin-mediated phagocytosis by the cells and to potentiate the cell's immune response.
An experimental study of vascularized tibiofibula grafts in inbred rats was performed. Roentgenologic and histologic changes of the grafted bone in the first seven postoperative weeks were especially investigated. After preliminary experiments on the vascular anatomy of the lower limbs of rats, tibiofibular vascularized grafts with femoral artery and vein were utilized in Fischer strain F-344 rats. The rate of bony union in the vascularized graft group was superior to that in the nonvascularized control groups. Fluorochrome-labeling studies of the grafted bone at the mid-diaphysis showed active periosteal new bone formation, following the vascularized graft. In contrast, normal tibial bone growth at the mid-diaphysis was mainly endosteal. However, both vascularized graft and normal bone demonstrated evidence of a "drift phenomenon" in the direction of growth. Since the life cycle of the rat is very short, compared with other laboratory animals, this experimental model may be useful in investigating the postoperative course of vascularized bone grafts with a short follow-up period.
Synthetic galanin, infused at a rate of 4 micrograms/kg body weight/h for 30 min, elicited a mild but significant hyperglycemia in conscious dogs and a fall in plasma insulin. Pancreatic glucagon, epinephrine, norepinephrine, cortisol and growth hormone levels were not affected significantly. The mild hyperglycemic action of galanin seems to be due to an inhibition of insulin production. Thus galanin appears to be involved in glucose homeostasis.
Two physalaemin (PHY)-like immunoreactive peptides, designated PHLIPs, have been purified from extracts of rabbit stomach tissue. Fast atom bombardment/mass spectrometry (FAB/MS) indicated that the m/z values for the PHLIP protonated molecular ions were 867.419 and 796.4. FAB/tandem MS spectra, coupled with a knowledge of the amino acid composition and the aid of a computerized fragment-matching program, indicated the amino acid sequences to be: (formula; see text) The sequences of PHLIPs-7 and -8 were confirmed with synthetic peptides. The PHY-antiserum cross-reactivity of the PHLIPs reflects homology at amino acid residues 1, 3, 4 and 5 for the mammalian and amphibian residues.
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