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Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 1,099 records · Page 61Linked to original sources
PubMed1988

Purification and characterization of aqualysin I (a thermophilic alkaline serine protease) produced by Thermus aquaticus YT-1.

Aqualysin I is an alkaline serine protease which is secreted into the culture medium by Thermus aquaticus YT-1. Aqualysin I was purified, and its apparent relative molecular mass was determined to be 28 500. The enzyme contained four Cys residues (probably as two cystines), and its amino acids composition was similar to those of cysteine-containing serine proteases (proteinase K, etc.) as well as those of subtilisins. The NH2-terminal sequence of aqualysin I showed homology with those of the microbial serine proteases. The optimum pH for the proteolytic activity of aqualysin I was around 10.0. Ca2+ stabilized the enzyme to heat treatment, and the maximum proteolytic activity was observed at 80 degrees C. Aqualysin I was stable to denaturing reagents (7 M urea, 6 M guanidine.HCl and 1% SDS) at 23 degrees C for 24 h. The enzyme hydrolyzed the ester bond of an alanine ester and succinyl-Ala-Ala-Ala p-nitroanilide, a synthetic substrate for mammalian elastase. The cleavage sites for aqualysin I in oxidized insulin B chain were not specific when it was digested completely.

Alkalies↗
PubMed1988

Fate of the ischaemic limb in Buerger's disease.

The clinical course of 328 patients with Buerger's disease (thromboangiitis obliterans: TAO) was followed. Neither ischaemic ulcers nor gangrene occurred in 26 per cent of the patients. Almost all of the ulcers occurred in patients between 20 and 50 years of age, with a peak incidence between 40 and 45 years. The younger the patient at the onset of the disease, the later the first ulcer occurred, and the later the first ulcer occurred, the shorter the period in which ulceration may recur. Recurrent ulcers were observed in 45 per cent of the patients. The progression of symptoms was influenced by smoking, but this was not the only deleterious factor as there were patients with stable TAO unaffected by smoking. In the 30 patients over the age of 60 years, ulceration and gangrene were not observed. In all patients, the progression of symptoms was self-limited and recurrent ulcers occurred less frequently with ageing. The rate of major amputation was low (3.9 per cent) although minor digital amputations were sometimes required. The survival rate of patients with TAO was higher than that of patients with arteriosclerosis obliterans. The aim of treatment in patients with TAO is to make patients abstain from smoking to prevent ulceration and to shorten the period of healing of trophic lesions without major amputation, as ulceration and gangrene in T AO are limited to the most distal part of the limbs, and seems to have healing potential.

Adult↗
PubMed1988

C7 deficiency and persistent haematuria.

A 14-year-old boy had persistent haematuria along with complete C7 deficiency. No significant changes in glomeruli and tubules were found in a renal biopsy specimen by light microscopy and immunofluorescence gave negative results for immune deposits. Electron microscopic examination demonstrated an attenuation of the glomerular capillary basement membrane without lamination and a diagnosis of thin basement membrane disease was made. It would be difficult to conclude that patients with C7 deficiency were predisposed to develop glomerulonephritis caused by immunologic aberrations. A family study failed to provide evidence of an association of C7 deficiency and thin basement membrane disease.

Adolescent↗
PubMed1988

Clinical experience of intrahepatic cholangiocarcinoma associated with hepatolithiasis.

Between 1960 and 1986, seven patients with intrahepatic cholangiocarcinoma and one patient with intrahepatic bile duct adenoma, related to hepatolithiasis, were seen among 112 cases of hepatolithiasis. Histopathologically, the tumors associated with hepatolithiasis arose from the periphery of the stone-containing bile duct, spread chiefly along the luminal surface, and invaded the ductal wall or periductal tissue. The tumors showed papillary to papillo-tubular proliferation and were diagnosed as the intraductal or periductal spreading type of cholangiocarcinoma. In addition, atypical epithelial hyperplasia was noted in the vicinity of the tumor area. These findings suggest that chronic relapsing cholangitis in patients with hepatolithiasis can induce progressive changes to atypical epithelial hyperplasia which may develop into cholangiocarcinoma.

Adenoma, Bile Duct↗
PubMed1988

A case of Vibrio vulnificus infection.

Vibrio vulnificus, a recently described strain of the halophilic Vibrio species, was isolated from the blood of a 73-year-old man, who developed rapidly progressive wound infection and fatal septicemia. Twenty-one patients with Vibrio vulnificus infection have been reported in the Japanese literature. Vibrio vulnificus most frequently causes primary septicemia and necrotising cellulitis after the eating of raw fish or shellfish or after exposure to seawater. The infection is characterized by its occurring during the warm months of the year, in patients with underlying diseases, especially liver diseases, and the mortality rate is surprisingly high. Clinicians should therefore consider the possibility of Vibrio vulnificus infection in the differential diagnosis of severe wound infections. Early surgical intervention and intensive antibiotic therapy are recommended for preventing the progress of the septicemia.

Aged↗
PubMed1988

Differences in basal and postexercise osteocalcin levels in athletic and nonathletic humans.

The levels of serum osteocalcin, in addition to other parameters, were monitored in athletic (N = 9) and nonathletic (N = 10) university male students before, immediately after, and 60 min after 30 min of exercise on a running ergometer and at a constant workload of approximately 50% of their maximum capacity; there was adequate replenishment of drinking water. In both groups, the increase in serum parathyroid hormone levels observed immediately after exercise correlated well with a decrease in ionized calcium as well as the total calcium, and also with an increase in serum phosphorus, whereas the concentration of serum albumin remained stable. The response of serum osteocalcin differed between the two groups, in that (1) the concentration before exercise was significantly higher in athletic than in nonathletic students (P less than 0.001), and (2) the maximum level was evident in the former group 60 min after exercise, whereas it was present in the latter group immediately after exercise. We speculate that athletic subjects have a higher turnover of bone status compared with nonathletic subjects.

Adult↗
PubMed1988

Post-replication repair and recombination in uvrA umuC strains of Escherichia coli are enhanced by vanillin, an antimutagenic compound.

Effects of vanillin on UV killing of umuC mutant strains of E. coli were investigated in order to analyze the antimutagenic role of vanillin in mutagenesis. UV-irradiated uvrA umuC cells showed higher survival when plated on medium containing vanillin rather than medium without vanillin. This increased survival associated with exposure to vanillin was observed more clearly in uvrA umuC lexA(Ind-) and uvrA umuC recF strains. However, the effect was inhibited by additional recB recC mutations and completely blocked by an additional recA mutation. As far as tested the increased survival of UV-treated cells by vanillin was dependent on a capacity for genetic recombination. The effect of vanillin on recombination frequency between 2 plasmid DNA, pATH4 (Cmr Tcs) and pBMX7 (Apr Tcs), in a uvrA umuC background was investigated. A significantly higher frequency of plasmid recombination was observed when vanillin was present in the culture medium. These findings suggest that the antimutagenic effect of vanillin is the result of enhancement of a recA-dependent, error-free, pathway of post-replication repair.

Benzaldehydes↗
PubMed1988

Suppression of mitomycin C-induced micronuclei in mouse bone marrow cells by post-treatment with vanillin.

Induction of micronuclei by mitomycin C (MMC) in mouse bone marrow cells was suppressed by post-treatment with vanillin, a component of vanilla essence flavour. Vanillin was given orally to mice 7.5 h after intraperitoneal injection of 2 mg/kg MMC. Post-treatment with vanillin at 500 mg/kg caused about 50% decrease in the frequency of micronucleated polychromatic erythrocytes (MN-PCEs). The effect of vanillin administration on the time-course of formation of MN-PCEs was also investigated. The suppressing effect was not due to a delay in the formation of MN-PCEs by the cytotoxic action of vanillin. Vanillin acts as an anticlastogenic factor in vivo.

Animals↗
PubMed1988

Time for acquiring a new gene by duplication.

In view of the widespread occurrence of gene families in eukaryotic genomes that suggests the importance of gene duplication in evolution, a population genetic model incorporating unequal crossing-over was formulated. By using this model, the time needed for acquiring a new gene is investigated by an approximate analytical method and by computer simulations. The model assumes that natural selection favors those chromosomes with more beneficial genes than other chromosomes in the population, as well as random genetic drift, mutation, and unequal crossing-over. Starting from a single gene copy, it is found that the time for acquiring another gene with a new function is dependent on the rates of occurrence of unequal crossing-over and mutation. Within a realistic range of parameter values, the required time was at least several times 4N generations, where N is the effective population size. Interchromosomal unequal crossing-over at meiosis is more effective than intrachromosomal (between sister chromatids) unequal crossing-over for obtaining a new gene, provided that other parameters are the same. However, the genetic load for acquiring a gene is larger under the model of interchromosomal crossing-over. The relevance of this finding to the advantage of sexual reproduction is discussed.

Alleles↗
PubMed1988

Evolution by gene duplication and compensatory advantageous mutations.

Relaxation of selective constraint is thought to play an important role for evolution by gene duplication, in connection with compensatory advantageous mutant substitutions. Models were investigated by incorporating gene duplication by unequal crossing over, selection, mutation and random genetic drift into Monte Carlo simulations. Compensatory advantageous mutations were introduced, and simulations were carried out with and without relaxation, when genes are redundant on chromosomes. Relaxation was introduced by assuming that deleterious mutants have no effect on fitness, so long as one or more genes free of such mutations remain in the array. Compensatory mutations are characterized by the intermediate deleterious step of their substitutions, and therefore relaxation by gene redundancy is important. Through extensive Monte Carlo simulations, it was found that compensatory mutant substitutions require relaxation in addition to gene duplication, when mutant effects are large. However when mutant effects are small, such that the product of selection coefficient and population size is around unity, evolution by compensatory mutation is enhanced by gene duplication even without relaxation.

Biological Evolution↗
PubMed1988

Determination of the positions of the disulfide bonds in aqualysin I (a thermophilic alkaline serine protease) of Thermus aquaticus YT-1.

Aqualysin I is a heat-stable alkaline serine protease produced by Thermus aquaticus YT-1. Aqualysin I comprises 281 amino acid residues and contains four cysteine residues. The cysteine residues seemed to form disulfide bonds in the molecule. Thus, the positions of the disulfide bonds were investigated. Disulfide bond-containing peptides were identified by peptide mapping with HPLC before and after carboxymethylation of chymotryptic peptides of aqualysin I. The disulfide bond-containing peptides were isolated and then carboxymethylated. Carboxymethylcysteine-containing peptides were purified, and their amino acid compositions and sequences were determined. Based on the data obtained and the primary structure of aqualysin I, it was concluded that two disulfide bonds were formed between Cys67 and Cys99, and between Cys163 and Cys194.

Chromatography, High Pressure Liquid↗
PubMed1988

Identification of the penicillin-binding active site of penicillin-binding protein 2 of Escherichia coli.

We determined the active site of penicillin-binding protein (PBP) 2 of Escherichia coli. A water-soluble form of PBP 2, which was constructed by site-directed mutagenesis, was purified by affinity chromatography, labeled with dansyl-penicillin, and then digested with a combination of proteases. The amino acid composition of the labeled chymotryptic peptide purified by HPLC was identical with that of the amino acid sequence, Ala-Thr-Gln-Gly-Val-Tyr-Pro-Pro-Ala-Ser330-Thr-Val-Lys-Pro (residues 321-334) of PBP 2, which was deduced from the nucleotide sequence of the pbpA gene encoding PBP 2. This amino acid sequence was verified by sequencing the labeled tryptic peptide containing the labeled chymotryptic peptide region. A mutant PBP 2 (thiol-PBP 2), constructed by site-directed mutagenesis to replace Ser330 with Cys, lacked the penicillin-binding activity. These findings provided evidence that Ser330 near the middle of the primary structure of PBP 2 is the penicillin-binding active-site residue, as predicted previously on the basis of the sequence homology. Around this active site, the sequence Ser-Xaa-Xaa-Lys was observed, which is conserved in the active-site regions of all E. coli PBPs so far studied, class A and class C beta-lactamases, and D-Ala carboxypeptidases. The COOH-terminal amino acid of PBP 2 was identified as His633.

Acyltransferases↗
PubMed1988

Natural human interferon-gamma derived from lipopolysaccharide-stimulated human myelomonocytic HBL-38 cells.

A human myelomonocytic cell line, HBL-38 cells, propagated in vivo, spontaneously produced interferon (IFN)-gamma and IFN-alpha. Whereas hemmagglutinating virus of Japan (HVJ) enhanced the production of IFN-alpha, bacterial lipopolysaccharide (LPS) markedly enhanced the production of IFN-gamma. LPS could be replaced with lipid A. Furthermore, the enhancement of production of IFN-gamma by LPS was completely abolished by polymixin B. IFN-gamma derived from LPS-stimulated HBL-38 cells was purified to homogeneity and characterized. The apparent molecular weight, subspecies composition, amino acid sequence and glycosylated sites were in agreement with those of the product of normal human peripheral blood lymphocytes (PBL). These results indicate that the myelomonocytic HBL-38 cells, not a T-cell line, can also produce IFN-gamma identical to the product of normal human PBL.

Amino Acid Sequence↗
PubMed1988

Development of substance P- and vasoactive intestinal polypeptide-containing neurones in the rat stomach.

The ontogeny and distribution of nerve fibres containing immunoreactive substance P (SP) and vasoactive intestinal polypeptide (VIP) were studied in the fetal and neonatal rat stomach, using immunohistochemistry and radioimmunoassay. Dimly fluorescent SP- and VIP-immunoreactive fibres began to appear in the myenteric plexus from embryonic day (ED) 17 and 18, respectively, and then in the circular muscle layer from ED 19. VIP-immunoreactive fibres increased in the mucosal layer after birth but not SP-immunoreactive fibres. Both immunoreactive fibres seemed to arise from intrinsic neurones in the stomach. SP and VIP were detectable from ED 15 and 18 in the rat stomach, respectively, by radioimmunoassay. The concentration of SP in the stomach increased until ED 18, but it tended to decrease somewhat thereafter. The concentration of VIP in the stomach increased throughout the period from ED 18 to 7 days post-natal. The results suggest that the development of VIP-containing neurones lags about 2 days behind that of SP-containing neurones in the rat stomach.

Aging↗
PubMed1988

Gastric vasodilatation and vasoactive intestinal peptide output in response to vagal stimulation in the dog.

1. Gastric vasodilatation, relaxation, and vasoactive intestinal peptide (VIP) output in response to vagal stimulation were studied in anaesthetized dogs. 2. Stimulation of the peripheral end of the vagus nerve (10 Hz, 40 V, 0.5 ms) normally evoked a gastric contraction, but caused relaxation in atropinized dogs. There was no detectable difference between the electrical thresholds for activation of the vagal preganglionic excitatory and inhibitory motor fibres. 3. Vagal stimulation also evoked gastric vasodilatation, which was blocked by hexamethonium but not by combined muscarinic and adrenergic blockade. Vagal fibres evoking vasodilatation had higher thresholds to electrical stimulation than those evoking motor responses. 4. Both gastric motor responses to vagal stimulation increased with increasing frequency up to 10 Hz and a plateau between 10 and 40 Hz, but the vasodilator response was significantly reduced above 20 Hz. Vagal stimulation at 10 Hz caused an increase in gastric venous VIP output which was significantly reduced at 40 Hz. 5. Low-intensity vagal stimulation (10 Hz, 40 V, 0.05 ms) elicited gastric relaxation (40% of a maximum), with no release of VIP or gastric vasodilatation. 6. It is concluded that release of VIP in response to stimulation of the vagal innervation to the stomach in the dog is primarily vasodilating in action.

Animals↗
PubMed1988

Gastric relaxation and vasoactive intestinal peptide output in response to reflex vagal stimulation in the dog.

1. Gastric relaxation, vasodilatation and vasoactive intestinal peptide (VIP) output from the stomach in response to stimulation of the central end of the cut vagus nerve were studied in anaesthetized dogs. 2. Central vagal stimulation (10 Hz, 40 V, 0.5 ms) normally produced a non-adrenergic, non-cholinergic (NANC) gastric relaxation via a vago-vagal reflex. It also caused an increase followed by a decrease in gastric blood flow. 3. The increase in blood flow was attributable to a NANC gastric vasodilatation via a vago-vagal reflex and the subsequent reduction in blood flow was decreased by splanchinicotomy. All these gastric and vascular responses were abolished by hexamethonium. 4. The gastric relaxation and vasodilatation induced by the vago-vagal reflex had similar stimulation frequency-response and pulse duration-response relations. 5. Central vagal stimulation caused an increase in gastric venous VIP output which was abolished by vagotomy or hexamethonium but unaffected by splanchnicotomy. 6. VIP injected into the gastric artery mimicked the gastric relaxant and vasodilator responses to the vago-vagal reflex. 7. We conclude that the intramural NANC inhibitory nerves activated by the vago-vagal reflex release VIP which causes both gastric relaxation and vasodilatation.

Animals↗
PubMed1988

Colicin E8, a DNase which indicates an evolutionary relationship between colicins E2 and E3.

Colicin E8-J and its immunity protein were characterized with regard to their activities and gene structures. Colicin E8 is a complex of proteins A and B; protein A (the naked E8) exhibits an apparently nonspecific DNase activity that is inhibited by protein B (the immunity protein), as in the case of colicin E2. The nucleotide sequence of the downstream half of the colicin operon of ColE8-J was determined to be highly homologous to that of ColE2-P9, with the exception of the hot spot region of the 3'-terminal segment of the colicin gene and the adjacent immunity gene. The immE2-like gene of ColE3-CA38 was, as assumed previously, extensively homologous to the immE8 gene of ColE8-J, and thus, ColE8-J was shown to be situated between ColE2-P9 and ColE3-CA38 in the evolution of the E-group Col plasmids.

Amino Acid Sequence↗