Autonomic innervation of the arteriovenous anastomoses in the dog tongue

Summary The innervation of the arteriovenous anastomoses in the dog tongue has been investigated. At the lightmicroscopic level, the vessels were found to be densely supplied with adrenergic and AChE-positive nerve plexuses and less densely with the quinacrine-binding nerve plexus. At the electron-microscopic level, at least two apparently different types of axon profiles were identified: 1) Small vesicle-containing axons, characterized by many small granular vesicles, variable numbers of small clear vesicles and large granular vesicles. Storage of endogenous amines and uptake of exogenous amines into most small granular vesicles and many large granular vesicles was demonstrated. These axons stained only lightly with reaction products for AChE activity and thus seemed to be adrenergic in nature. Some axons contained numerous large granular vesicles, whose cores occasionally stained with uranyl ions; this suggests a co-localization of ATP or peptides as neurotransmitters. 2) Small granular vesicle-free axons, containing small clear vesicles and large granular vesicles in variable ratio. Most cores of these large granular vesicles were heavily stained with uranyl ions. No storage or uptake of amine into the synaptic vesicles was detected. Some axons appeared to be typically cholinergic, some, typically non-adrenergic, noncholinergic, and the rest, intermediate between the two. All axons stained heavily with reaction products for AChE activity, suggesting their cholinergic nature.     

Effects of chronic bifemelane hydrochloride administration on receptors for N-methyl-d-aspartate in the aged-rat brain

We assayed N-methyl-d-aspartate (NMDA) receptors [³H]3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid ([³H]CPP) bindings) and evaluated their distribution in the brain by quantitative autoradiography in young adult and aged rats. In the young adult rats, NMDA receptors were present at relatively high concentrations in the cerebral cortex and hippocampus. In the aged rats, NMDA receptors were decreased in the nealy all areas of the brain, especially in the cerebral cortex and hippocampus. Chronic administration of bifemelane hydrochloride, a drug for sequela of cerebrovascular diseased, at a dose of 15 mg/kg/day for 14 days, markedly attenuated these decrease in NMDA receptors. Since NMDA receptors are considered to be involved in memory and learning processes, our results suggest that bifemelane hydrochloride may be applicable to the treatment of disturbed memory and learning.     

Molecular cloning of complementary DNA encoding one of the human pancreatic protease E isozymes

We have cloned a DNA from a human pancreatic cDNA library using a cloned rat pancreatic elastase 1 cDNA as a probe, and determined its nucleotide sequence. This cDNA contains a coding region of 810 nucleotides which encodes a 270-amino-acid protein. The deduced amino acid sequence shows less than 60% homologies with rat and porcine pancreatic elastase 1, although its substrate binding region is homologous with those of the above elastases 1. When this deduced amino acid sequence was compared with known amino acid sequences of pancreatic proteases other than elastases, it was found to contain an amino acid sequence which was highly homologous with the N-terminal amino acid sequence of porcine pancreatic protease E. We also purified human pancreatic protease E isozymes from human pancreatic juice, and determined their N-terminal amino acid sequences. One of the isozymes does not hydrolyze elastin but does hydrolyze a synthetic substrate. Endoglycosidase F digests glycoside bonds of the isozyme. These results suggest that the cDNA cloned by us corresponded to one of the human protease E isozymes.     

Effects of chronic treatment with a novel angiotensin converting enzyme inhibitor, CS622, and a vasodilator, hydralazine, on atrial natriuretic factor (ANF) in spontaneously hypertensive rats (SHR)

We studied the effects of chronic treatment with a novel angiotensin converting enzyme inhibitor, alpha-[(2S,6R)-6-[(1S)-1-ethoxycarbonyl-3-phenylpropyl]amino-5-oxo-2- (2-thienyl)perhydro-1,4-thiazepin-4-yl]acetic acid.HCl (CS622), and a vasodilator, hydralazine, on plasma atrial natriuretic factor (ANF) levels and kidney ANF receptors in spontaneously hypertensive rats (SHR). Plasma ANF level was decreased and cardiac hypertrophy reduced in CS622 treated SHR, but not in hydralazine treated SHR, although blood pressure was lowered similarly in both SHR groups. The binding capacity of kidney ANF receptors increased and the affinity decreased in CS622 treated SHR compared to untreated SHR. These results suggest that decrease of plasma ANF results from decreased cardiac load but not from lowered blood pressure, and that changes in ANF receptors result from increased plasma ANF.     

Characterization of an essential histidine residue in thermophilic malate dehydrogenase

Heat-stable malate dehydrogenase isolated from Thermus flavus AT62 was completely inactivated by treatment with diethylpyrocarbonate. The inactivation was accompanied by the loss of 1.2 histidine residues per subunit of the enzyme. The enzyme was protected from inactivation by NADH. The enzyme was also inactivated by dye-sensitized photooxidation. Methionine residues, in addition to histidine residues, were destroyed in the inactivated enzyme. Kinetic analyses of the inactivation indicated that the pK value of the residue involved in the inactivation was 8.20 at 25.0 degrees C and 7.52 at 60.0 degrees C. From the pK values and the heat of ionization calculated from the van't Hoff plot of pKs, a histidine residue was identified to be primarily involved in the inactivation. The effect of temperature on the pK value of the essential group in this enzyme from a thermophilic organism is discussed.     

Highly potent and specific inhibitors of human renin

We designed aldehyde derivatives of small peptides representing the C-terminal portion of angiotensin I sequence as an inhibitor of human renin. Among compounds that we synthesized, benzyloxycarbonyl (Z)-Phe-His-Leucinal (compound V), Z-Pro-Phe-His-Leucinal (Compound IV) and Z-[3-(1'-naphthyl)Ala]-His-Leucinal (compound VII) markedly inhibited human renin (IC50, 7.5 X 10(-7), 3.2 X 10(-7) and 8.0 X 10(-8) mol/l, respectively). Compound VII was shown to be noncompetitive (Ki = 2.4 X 10(-7) mol/l). It did not inhibit either cathepsin D or pepsin. Compound V had slight or no inhibitory effect at the concentration of 10(-5) mol/l on six animal renins except for monkey and rabbit renins. Results obtained show that these aldehyde compounds are highly selective and species specific inhibitors for human and monkey renins.     

An inducible lactone hydrolase yielding 2,5-diphenyl-3-hydroxy-4-oxo-2-hexendioic acid from pulvinic acid

The metabolism of vulpinic acid by an unclassified soil micro-organism was studied. A new compound, 2,5-diphenyl-3-hydroxy-4-oxo-2-hexendioic acid (DHOHA) was isolated from the reaction mixture of a cell-free preparation and pulvinic acid. The existence of a hydrolase which catalyses the conversion of vulpinic acid to pulvinic acid was detected in cell-free preparation, and an inducible lactone hydrolase capable of converting pulvinic acid to DHOHA was purified 130-fold and characterized. This enzyme had a MW of ca 34 000, a K_m for pulvinic acid at pH optimum (pH 7.0) less than 10 ^{? 6} M, pI = 5.0, and was inhibited by p-chloromercuriphenylsulfonate and diethylpyrocarbonate. The enzyme was highly specific for pulvinic acid. The initial degradative steps proposed for this organism are vulpinic acid → pulvinic acid → DHOHA.