Neuromedin B is a novel decapeptide which has recently been isolated from porcine spinal cord and shows striking sequence homology with bombesin-like peptides at the C-terminal region. The effect of synthetic neuromedin B on the secretion of gastrointestinal and pancreatic regulatory peptides has been compared with bombesin in the rat. Insulin, glucagon, enteroglucagon, gastrin, cholecystokinin (CCK) and bombesin were measured in plasma by radioimmunoassays. Neuromedin B (1.0 nmol) had significant stimulatory effects on insulin, enteroglucagon, gastrin and CCK release, similar in pattern but slightly less potent than those of bombesin (1.0 nmol). Neuromedin B had no significant effect on plasma concentrations of glucagon and bombesin. These results suggest the possibility that neuromedin B could be one of the neural factors which play a regulatory role in the control of the endocrine pancreas and gastrointestinal tract.

Assembly of each component of the neurofilaments from bovine brain was examined, and it was revealed that not only P 68 component but also P 200 and P 160 component make component-specific filaments. It was observed with electron microscope that P 200 made side arm like short filaments and P 160 made semilong filaments with rough surface. P 68 made very long filaments with smooth surface as already reported. The fine structures of each filament seem to be compatible with the structures predicted from the microscopic observation of the native neurofilaments and from component-specific antibody decoration study. Namely, it seems that P 200 makes side arms of the neurofilament, and rough surface of the neurofilament is due to P 160 filaments twisting around core filaments of P 68. These results were confirmed by centrifugal and electrophoretic methods.

Neurofilaments from the rat spinal cord and porcine brain stem are phosphorylated by a Ca²⁺-calmodulin-dependent protein kinase (M.W. 640 K), and also by the catalytic subunit of type II cyclic AMP-dependent protein kinase from the brain. Weak protein kinase activity is endogenously associated with neurofilaments, but this activity is not stimulated by Ca²⁺ plus calmodulin, nor by cyclic AMP. Glial fibrillary acidic protein from the spinal cord is also phosphorylated by the Ca²⁺-calmodulin-dependent protein kinase and the catalytic subunit.

The microvascular architecture of rat duodenal mucosa was investigated by scanning electron microscopy of vascular corrosion casts, and of fractured tissue specimens in which the interstitial matrix had been digested by acid/enzyme treatment. Light microscopy of cleared tissues, in which the vasculature had been injected with silicone elastomer, was used to define the spatial organization of the larger supply/drainage vessels. Within the mass of Brunner’s glands, possibly because of its compact nature, it proved impossible to define differing microvascular networks related to particular functional regions of the glands (acini and ducts). The microvascular bed of Brunner’s glands is, however, clearly a separate vascular bed from that of the rest of the duodenal mucosa, and is arranged essentially in parallel to it; it is argued that this separation of venous outflow from the glands may be important in maintaining the HCO₃^- protection of the duodenal surface from acid erosion. Microvascular architectural differences in the villi and intestinal gland regions, compared to more distal rat small intestine, include an apparently denser villus subepithelial capillary network origin of villus venules closer to the villus tip, and frequent direct drainage of the pericryptal network into adjacent venules.

In the rabbit ear artery, stimulation ofperivascular nerves elicited an excitatory junction potential (e.j.p.) and a slow depolarization; the amplitude of the e.j.p. related to that of the slow depolarization. In the artery from the reserpine-treated rabbit, the slow depolarization was abolished, and only the e.j.p. was generated, even with intensive stimulation. Reserpine treatment reduced the tissue content of noradrenaline below 1% of the control, and abolished the outflow of noradrenaline induced by perivascular nerve stimulation; depolarization of smooth muscle membrane to exogenously applied noradrenaline remained unchanged under this condition. Thus, the reserpine treatment dissociated the e.j.p. from the slow depolarization, and the latter component related to the noradrenaline stored in the nerve terminals. Iontophoretic application of noradrenaline or ATP depolarized the smooth muscle membrane of the rabbit ear artery; the former decayed slowly and the latter rapidly. Possible transmitter substances involved in the generation of e.j.p. were discussed.

Human [Ala^B23]-, [Ala^B24]-, [Aｌa^B25]- and [Ala^B26]-insulins were semisynthesized from porcine insulins by enzyme-assisted coupling method. Receptor binding ability of [Ala^B23]-,[Ala^B24]-, [Ala^B25]-, and [Ala^B26]-insulins was 3, 5, 10, and 100% of that of normal human insulin. Biological activity assessed by glucose uptake and glucose oxidation in isolated rat adipocytes was also impaired in a similar fashion. Immunoreactivity of [Ala^B25]- and [Ala^B26]-insulins was not affected, whereas [Ala^B23]-and [Ala^B24]-insulins bind very weakly to anti-porcine insulin antibodies. These results suggest that alanine at 23, and phenylalanine at 24 and 25 in the B-chain are crucial for receptor binding, whereas tyrosine at 26 does not play any important role in receptor binding and antibody recognition.

The effect of feeding guar gum or bran fibre diets upon the incidence of renal tumors was examined in streptozotocin diabetic rats. Guar gum fed rats gained significantly less weight during the first 14 weeks of the study than the bran fibre group. At 18 weeks, six rats from each group were sacrificed; two bran fibre rats had renal tumors. At the end of the study (42 weeks), significantly (P<0.005) fewer renal tumors were found in the guar gum group (12%; 3/25) compared with the bran fibre group (69%; 25/36). This dramatic reduction of renal tumor incidence associated with guar gum consumption warrants further investigation.

The level of crosslinking in human tendon collagen of various ages was assessed by measuring the amount of solubilized peptides after cyanogen bromide digestion. The result suggests that progressive crosslinking occurs throughout adult life. The fluorescence properties of the aged collagen indicate that nonenzymatic browning or the Maillard reaction may be involved in the crosslinking process.

We examined the effect ofneuraminidase on the reactivity of anti-myelin-associated glycoprotein (MAG) antiserum with human natural killer cells. The percentage of MAG-positive cells was increased threefold by neuraminidase treatment, whereas the percentage of Leu-7-positive cells (natural killer cells) was unchanged. It is possible that the antigenic determinant masked by sialic acid is exposed after the neuraminidase treatment. Since most MAG-positive cells in neuraminidase-untreated mononuclear cells are also stained by anti-Leu-7, the antigenic determinants may differ between the treated and untreated cell membrane.

A potassium current activated by influx of Ca²⁺ into presynaptic terminals has been found in mouse motor endings. Its detection is greatly aided by blocking delayed rectifier K⁺ channels by 3,4-diaminopyridine (DAP). Ca²⁺-activated K⁺ current was readily abolished by tetraethylammonium (TEA) and by procedures which interfere with Ca²⁺ current.

Renal complications in non-obese diabetic (NOD) mice treated with insulin for 5 months after the onset of diabetes were studied using light and electron microscopy. Periodicacid-Schiff (PAS)-positive materials, fibrinoid cap formation and an increase in mesangial cells and matrix in the glomeruli were seen in animals survived for 4 months. Electron microscopy revealed glomerular basement membrane thickening and mesangial deposits of fibrillar materials. These findings were not observed in mice survived for 2 months. Since renal complications develop spontaneously in NOD mice despite insulin treatment, these animals may be useful for studying human diabetic nephropathy.