Excitation conduction in Meissner's plexus of rabbit small intestine

Excitation conduction in Meissner's plexus of the rabit small intestine was investigated by analyzing the records of potentials evoked by a single electrical stimulus applied to this plexus. Experiments were performed on the Meissner's plexus that remained attached to the circular muscle after the longitudinal muscle and mucous membrane were removed from intestinal segment. Conduction velocities of nerve impulses were 0.3-0.7 m/s, chronaxie of the nerve bundle was 0.06-0.12 ms. While the distance between the stimulating and recording electrodes was increased, the latency of evoked potentials was prolonged, the number increased, and the amplitude decreased; no potentials could be recorded when the distance was more than 4 mm. Evoked potentials recorded at relatively long conduction distance were reduced in amplitude or abolished after a repeated stimulation with high frequencies above 50/s, after hexamethonium application, and in a state of lack of oxygen. It was concluded that, in Meissner's plexus, nerve impulses spread through multiple pathways and make synaptic transmission at a relatively short conduction distance.

Congenital brain defect masked by subdural fluid collection

Two rare cases of subdural fluid collection are reported. In these cases, the subdural space was in direct communication with the lateral ventricle through the congenital brain defects. The subdural fluid was formed by the cerebrospinal fluid which passed from the lateral ventricle through the brain defects. The difficulty to diagnose these cases from the usual subdural hygroma is emphasized.

Effect of stirring during fixation upon immunofluorescence. Results with distribution of albumin-producing cells in liver

When the immunofluroscent study on the distribution and the incidence of albumin-producing hepatocytes in the rat liver was performed by the method of Sainte-Marie, the number of positive cells showed various values (10-60%). It was surmised that when the permeability of the fixative was delayed, albumin had flowed out from the cytoplasm of the unfixed hepatocytes. By the simple means of constant stirring of the fixative using a magnetic stirrer, we accomplished rapid fixation and achieved results in which positive cells attained 100%. On the other hand, the incidence of positive cells decreased markedly when rats were fed a protein-free diet.

The evolutionary advantage of recombination. II. Individual selection for recombination

Based on the FISHER-MULLER theory of the evolution of recombination, an argument can be constructed predicting that a recessive allele favoring recombination will be favored, if there are either favorable or deleterious mutants occurring at other loci. In this case there is no clear distinction between individual and group selection. Computer simulation of populations segregating for recessive or dominant recombination alleles showed selection favoring recombination, except in the case of a dominant recombination allele with deleterious background mutants. The relationship of this work to parallel investigations by WILLIAMS and by STROBECK, MAYNARD SMITH, and CHARLESWORTH is explored. All seem to rely on the same phenomenon. There seems no reason to assume that the evolution of recombination must have occurred by group selection.

Some properties and electrophoretic patterns of rat liver esterases in relation to hepatocarcinogenesis by 3'-methyl-4-(dimethylamino) azobenzene

Five distinctly different types of naphthyl acetate esterase in rat liver were examined for study of liver enzymes during hepatocarcinogenesis. Three types of esterase in normal adult liver were separated by column chromatography. Main esterase in adult hepatocytes, which was demonstrated near the origin in cellulose acetate electrophoresis, was very sensitive to diisopropyl phosphorofluoridate (DFP). The other two esterases showed different electrophoretic mobility, while their Km values did not differ and both were considerably resistant to DFP. An anodic minor component in normal adult liver, which had a characteristic esterase pattern of infant liver, increased in the liver of rats fed 3'-methyl-4-(dimethylamino) azobenzene. This esterase was obtained by electrophoresis on Cellogel block. It was partially inhibited by DFP and p-chloromercuribenzoate, activated by cysteine, and showed a different Km value from the above esterases. Another minor component situated at the most cathodic side, which had characteristic esterase patterns of fetal liver and hepatoma, was very sensitive to DFP and eserine, and showed a characteristic of nonspecific cholinesterase as proved by staining.

Pheochromocytoma with renal artery stenosis and high plasma renin activity

An unusual case of pheochromocytoma is described in this communication. Besides a chain of typical clinical pictures and laboratory findings which suggested a catecholamine-producing tumor, the left renal artery stenosis was demonstrated by an aortography and the plasma renin activity was consistently elevated. Surgery revealed the left renal artery was embedded in the tumor mass, originated from the left adrenal gland, resulting in a high degree of constricture of the vessel. Following the removal of the tumor, blood pressure immediately returned to normal, however, plasma renin activity remained elevated as long as 9 months of the follow-up study. The second aortography performed 14 months after the operation failed to demonstrate the left renal artery stenosis and subsequent studies revealed that plasma renin activity was gradually declining to upper normal levels. It is suggested that an excess of catecholamines secreted by the tumor was responsible for hypertension in this case, and that another factor, probably renal artery stenosis, was involved in the elevation of plasma renin activity, although this high renin activity was maintained for more than 9 months following the tumor extirpation.

Kininase and anti-inflammatory activities of acid carboxypeptidase from Penicillium janthinellum

The acid carboxypeptidase from Penicillium janthinellum catalyzed the rapid release of arginine, and the slow release of phenylalanine, proline, serine and glycine from the carboxy-terminal of bradykinin at pH 4.15 to 4.8. Anti-inflammatory activity of the acid carboxypeptidase seems to suggest that the enzyme hydrolyzed bradykinin in vivo.

Action of crystalline acid carboxypeptidase from Penicillium janthinellum

Acid carboxypeptidase (EC 3.4.12.-) crystallized from culture filtrate of Penicillium janthinellum has been investigated for its use in carboxy-terminal sequence determination of Z-Gly-Pro-Leu-Gly, Z-Gly-Pro-Leu-Gly-Pro, angiotensin I, native lysozyme, native ribonuclease T1, and reduced S-carboxy-methyl-lysozyme. The examination indicated that proline and glycine were liberated from Z-Gly-Pro-Leu-Gly-Pro. At high enzyme concentration, the enzyme catalyzed complete sequential release of amino acids from the carboxy-terminal leucine to the amino-terminal aspartic acid of angiotensin I. The enzyme released the carboxy-terminal leucine from native lysozyme, however, no release of the threonine from native ribonuclease T1 was observed after a prolonged period of incubation with the enzyme. The sequence of the first nine carboxy-terminal residues of denatured lysozyme, leucine, arginine, S-carboxymethyl-cysteine, glycine, arginine, isoleucine, tryptophane, alanine, and glutamine, could be deduced unequivocally from a time release plot of an incubation mixture with the enzyme.

Submerged production, purification, and crystallization of acid carboxypeptidase from Penicillium janthinellum IFO-8070

Penicillium janthinellum IFO-8070 produced an acid carboxypeptidase of molecular weight 51,000 in a liquid medium at 25 C. Maximum enzyme concentration was obtained within 3 to 6 days in a medium containing 2% wheat bran, 1% defatted soybean, and 1% KH(2)PO(4); the initial pH was 2 to 4. When submerged aerobic conditions were used, a 51,000-molecular-weight acid carboxypeptidase was produced and no detectable amounts of 160,000-molecular-weight acid carboxypeptidase were produced. Acid carboxypeptidase with a molecular weight of 51,000 was purified 330-fold from koji culture to yield a crystalline protein which was demonstrated by disc electrophoresis to be homogeneous. The purification method included ammonium sulfate fractionation, Amberlite CG-50 chromatography, acetone fractionation, Amberlite CG-50 rechromatography, and concentration in a collodion bag. The specific activity of the enzyme was about three times more than that of the acid carboxypeptidase from Aspergillus saitoi.

Production and some properties of a new type of acid carboxypeptidase of Penicillium molds

Among some 38 strains of the genus Penicillium we investigated seven wild-type strains (P. daleae IFO-6087, P. frequentans AHU-8328, P. funiculosum IAM-7013, P. janthinellum IFO-8070, IAM-7026, P. lividum IAM-7200, and P. oxalicum AHU-8336) that were found to be excellent strains for a new type of acid carboxypeptidase production in a surface koji culture at 25 C. The production of acid carboxypeptidase was determined in various culture conditions in a koji culture. The maximum yields of acid carboxypeptidase were obtained by P. janthinellum IFO-8070. Partial purification and isolation of the acid carboxypeptidase from strains of Penicillium were performed with gel filtration on Bio-Gel P-100. Characterization studies indicate that the acid carboxypeptidases from P. daleae IFO-6087, P. funiculosum IAM-7013, P. janthinellum IFO-8070, and P. oxalicum AHU-8336 have some properties similar to those of the enzyme of Aspergillus saitoi with regard to the hydrolysis of several peptides at acidic pH range but have other slightly different properties with regard to stability, pH optima, inhibitors, and molecular weights.