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Biomedical subjects

M Ohta

Publications and source records attributed to M Ohta.

At least 505 records · Page 28Linked to original sources
PubMed1995

A novel integron-like element carrying the metallo-beta-lactamase gene blaIMP.

A plasmid-mediated metallo-beta-lactamase gene was cloned from a carbapenem-resistant Serratia marcescens strain, AK9373. The metallo-beta-lactamase gene was identical to the blaIMP, and it was located in the space between an integrase-like gene and an aac(6')-Ib-like gene. The deduced amino acid sequence for the putative integrase gene showed considerable identity (60.9%) to that of the Escherichia coli integrase reported. Sequences similar to the GTTRRRY and an atypical 59-base element containing a 67-bp inverted repeat sequence, which were peculiar to the integrase-dependent recombination, were also conserved in the flanking regions of the blaIMP gene. These findings imply that the metallo-beta-lactamase gene in S. marcescens AK9373 is carried by a novel integron-like element that is mediated by a transferable large plasmid.

Amino Acid Sequence↗
PubMed1995

Effect of pH on activities of novel beta-lactamases and beta-lactamase inhibitors against these beta-lactamases.

The effects of acidic conditions on activities of seven beta-lactamases--TEM-1 (class A), KOXY (class A), IMP-1 (class B), AmpC (class C), MOX-1 (class C), OXA-5 (class D), and PSE-2 (class D)--and their inhibitors were measured. The enzymatic activities of KOXY, IMP-1, and MOX-1 at pH 5.8 were slightly lower than those at pH 7.5. However, the activities of PSE-2 and OXA-5 were greatly reduced at pH 5.8. All of the beta-lactamase inhibitors tested had poorer inhibitory activities at pH 5.8 than at pH 7.5 except clavulanic acid for TEM-1.

Anti-Bacterial Agents↗
PubMed1995

Genomic organization of the Klebsiella pneumoniae cps region responsible for serotype K2 capsular polysaccharide synthesis in the virulent strain Chedid.

The genomic organization of the chromosomal cps region that is responsible for capsular polysaccharide synthesis in Klebsiella pneumoniae Chedid (O1:K2) was investigated. Deletion analyses and Southern hybridization studies suggested that the central region of the cloned 29-kb BamHI fragment is indispensable for K2 capsular polysaccharide synthesis. The 24,329-bp nucleotide sequence of the Klebsiella cps region was determined and deposited in the EMBL and GenBank databases through DDBJ and assigned accession number D21242. Nineteen possible open reading frames (ORFs) were identified in the sequenced area. Among them, 13 ORFs are very close to each other. Six of the 19 ORFs show considerable nucleotide sequence similarities to Salmonella typhimurium cpsG, cpsB, rfbP, and orf2.8, Escherichia coli gnd, and Haemophilus influenzae bexD, respectively. Moreover, the deduced amino acid sequence of the ORF10 product demonstrated a highly hydrophobic profile and showed putative membrane topology similarity to Rickettsia prowazekii ATP/ADP translocase. Nucleotide sequence similar to the sigma 54-dependent promoter, as well as the usual -35 and -10 sequences, were identified just upstream of ORF3, which is the first ORF in the polycistronic structure. Furthermore, a sequence (GGGCGGTAGCGT) found just downstream of the sigma 54-dependent promoter-like sequence was generally conserved among gene clusters implicated in cell surface polysaccharide synthesis, such as Salmonella rfb and viaB and E. coli kpsMT and rfaQPG. A possible transcriptional terminator with a hairpin loop structure found just downstream of ORF15 that is a homolog of E. coli gnd. K2 capsular polsaccharide biosynthesis in E. coli K-12 depends on cpsB (mannose-1-phosphate guanyltransferase gene), and Klebsiella cpsB, found in the downstream region of the polycistronic structure, was able to complement cpsB of E. coli. Results of transposon insertion and promoter-cloning analyses were consistent with the results of nucleotide sequence analysis.

Amino Acid Sequence↗
PubMed1995

Decline in glucose metabolism in the brain in neuronal ceroid lipofuscinosis (NCL) in English setter--evidence by positron emission tomography (PET).

Positron emission tomography scans were performed on brains of homozygous and heterozygous English setters with neuronal ceroid-lipofuscinosis (NCL) from 13 months of age to 24-25 months of age for homozygous dogs and to 38 months for heterozygous dogs, respectively. After iv injection of 18F-fluorodeoxyglucose (FDG), 7 coronal brain scans as well as sequential arterial blood samplings were performed for 45 min under pentobarbital anesthesia. From these data, three different functional images (DAR (standardized uptake value), FDG uptake (fractional uptake) and glucose uptake) were reconstructed and quantitatively analysed. In the age range from 13 to 15 months, glucose images were comparable for both homozygous and heterozygous dogs, so that no differentiation was possible between healthy and diseased dogs on the basis of PET findings. Between 18 and 24 months of age, a drastic decline in glucose metabolism was observed in homozygous dogs, while the decline in glucose utilization was very mild in this period for heterozygous dogs. Furthermore, in PET scans, cerebral atrophy and ventricular enlargement were clearly shown in homozygous dogs. Consequently at the age from 20 to 24 months, a clear differential diagnosis between healthy (heterozygous) and diseased (homozygous) dogs became possible even if the clinical symptoms were still not clear in the latter. We conclude that the biochemical alterations in the brain in canine NCL occurs and progresses very rapidly in the last quarter of their lives.

Aging↗
PubMed1995

Recurrent brief episodes with psychotic features in adolescence: periodic psychosis of puberty revisited.

BACKGROUND: There are many reports of adolescents with periodic episodes each followed by complete remission within 2 weeks, but the nosology and long-term prognosis of such cases have not been elucidated. METHOD: A prospective follow-up study on 11 cases (nine girls and two boys) meeting predetermined criteria is reported. RESULTS: The first several episodes were found to meet ICD-10 symptomatic criteria for recurrent depressive disorder in all cases, and except for two cases, showed psychotic features. The episodes were linked to one phase of the menstrual cycle in only two of six girls with regular menses. There were no recurrences while on lithium in eight of nine cases. Of eight patients followed up 5-14 years after the first onset, three had been well, three had become bipolar and two were still suffering from brief depressive episodes. CONCLUSIONS: Recurrent brief episodes in adolescence tend to show a near-monthly rhythm and psychotic features. Most of them appear to the manifestations of affective illness and may be treated and prevented as such.

Adolescent↗
PubMed1995

Insulin receptor-related receptor messenger ribonucleic acid in the stomach is focally expressed in the enterochromaffin-like cells.

The insulin receptor-related receptor (IRR) is a member of the insulin receptor family. In contrast to the widespread expression of insulin receptor and insulin-like growth factor-I receptor messenger RNA (mRNA), the expression of IRR mRNA is highly restricted to the kidney and stomach. IRR mRNA in the kidney is focally expressed in the renal distal tubule cells. However, the cellular localization of IRR mRNA in the stomach remains to be elucidated. Here, we examined the cellular localization of IRR mRNA in the rat stomach by in situ hybridization. IRR mRNA in the stomach was abundantly localized in the basal third of the oxyntic glands of the fundic stomach. IRR mRNA in the stomach was colocalized with mRNA for histidine decarboxylase, a marker for the enterochromaffin-like (ECL) cells, indicating that the expression was restricted to ECL cells. ECL cells actively produce and store histamine, which is an important physiological stimulant of acid secretion from the parietal cells. The preferential localization of IRR mRNA in ECL cells suggests that the IRR plays an important role in the function of these cells.

Animals↗
PubMed1995

No association of the 11778 mitochondrial DNA mutation and multiple sclerosis in Japan.

Leber's hereditary optic neuropathy (LHON), a maternally inherited disease causing severe bilateral visual loss in young men, is linked to 12 point mutations in mitochondrial DNA, the most common of which is at the nucleotide position 11778. The 11778 point mutation has also been detected in several patients with possible multiple sclerosis (MS), especially women with severe visual loss in both eyes. Because frequent and severe optic neuropathy is a feature of MS in Japan, we screened 80 Japanese MS patients for the presence of the 11778 mutation by mutation-specific polymerase chain reaction. Eighteen women with MS had bilateral optic neuropathy, but none had the mutation at 11778. There is no association between Japanese MS and the 11778 mitochondrial DNA mutation.

Base Sequence↗
PubMed1995

New 1,4-benzodiazepin-2-one derivatives as gastrin/cholecystokinin-B antagonists.

A novel series of 1-aroylmethyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one derivatives was prepared and evaluated for activity as gastrin/cholecystokinin (CCK)-B receptor antagonists. In vitro binding studies showed that some derivatives exhibited potent affinity for gastrin CCK-B receptor and high selectivity over peripheral CCK(CCK-A) receptor. Furthermore these compounds potently inhibited pentagastrin-induced gastric acid secretion upon intravenous administration in an in vivo model in rats. Structure-activity relationship studies of this series suggested that 1-[(R)-2,3-dihydro-1-(2,3-dihydro-1-(2-methylphenacyl)-2-oxo-5-phe nyl-1H-1,4-benzodiazepin-3-yl]-3-(3-methylphenyl)urea (35b, YM022) was the optimal compound with IC50 values of 0.17, 0.11 and 150 nM for gastrin, CCK-B and CCK-A receptors, respectively, and an ED50 value of 9.5 nmol/kg (i.v.) in rats. The absolute configuration of the precursor of YM022, an (R)-3-amino-1,3-dihydro-2H-1,4-benzodiazepin-2-one derivative ((R)-25), was determined by X-ray crystallographic analysis of its (S) mandelate. It would be expected that YM022, a potent and selective gastrin CCK-B receptor antagonist, inhibits gastric acid secretion without inducing gastrin-mediated side effects such as hypergastrinemia and hyperplasia of oxyntic mucosa.

Anesthetics↗
PubMed1995

Antisecretory and antiulcer effects of YM020, a new H+,K(+)-ATPase inhibitor, in rats and dogs.

We examined the effects of YM020 (3-cyanomethyl-2-methyl-8-[(3-methyl-2-butenyl)oxy]-imidazo[1,2- a]pyridine), a novel H+,K(+)-ATPase inhibitor, on gastric acid secretion and experimental gastroduodenal lesions in rats and dogs. Intraduodenal, subcutaneous and oral YM020 inhibited basal gastric acid secretion in pylorus-ligated rats with ED50 values of 9.1, 9.1 and 9.5 mg/kg, respectively. Oral pretreatment with YM020 5 hr before ligation still suppressed acid secretion, with a potency a little less than that of omeprazole. In anesthetized dogs, intravenous YM020 inhibited histamine-, methacholine- and pentagastrin-induced gastric acid secretion with ED50 values of 0.05, 0.01 and 0.08 mg/kg, respectively. In Heidenhain pouch dogs, although oral YM020 (3 mg/kg) inhibited histamine-induced acid secretion, acid output returned to control levels faster than in dogs treated with omeprazole. Oral YM020 inhibited the formation of water-immersion restraint stress-, indomethacin-, absolute ethanol-, 0.7 N hydrochloric acid- and cysteamine-induced gastric or duodenal lesions with ED50 values of 2.9, 4.3, 2.0, 11.7 and 8.4 mg/kg, respectively. Moreover, subcutaneous YM020 also suppressed the formation of ethanol- and HCl-induced gastric lesions. These results suggest that YM020 has an antisecretory effect almost the same as or 2 to 3 times weaker than those of omeprazole and that its duration is not as long as that of omeprazole in rats and dogs. Furthermore, YM020 possesses a cytoprotective effect and the mechanism of YM020 may be different to that of omeprazole.

Administration, Oral↗
PubMed1995

Purification and characterization of two chitinases from the leaves of pokeweed (Phytolacca americana).

Two chitinases, designated PLC-A and PLC-B, were purified from the leaves of pokeweed (Phytolacca americana) using DEAE-cellulose column chromatography followed by gel filtration on Sephadex G-75, hydrophobic column chromatography, and ion-exchange FPLC. PLC-A and PLC-B are acidic and basic proteins having molecular masses of 25 and 29 kDa, and isoelectric points of 3.7 and 9.5, respectively. On the basis of their partial amino acid sequences, it was seen that PLC-A and PLC-B belong to class II and class III chitinases, respectively. The optimal pH of PLC-A toward glycolchitin is pH 4.5 and hydrolyzed (GlcNAc)4 into 2(GlcNAc)2, and (GlcNAc)5-6 into (GlcNAc)2 and (GlcNAc)3. on the other hand, PLC-B has two optimal pHs at 3 and 7 toward glycolchitin and hydrolyzed (GlcNAc)5 into GlcNAc and (GlcNAc)4, and (GlcNAc)6 into GlcNAc, (GlcNAc)2, and (GlcNAc)4.

Amino Acid Sequence↗
PubMed1995

Evaluation of anthelmintic efficacy of doramectin against gastrointestinal nematodes by fecal examination in cattle in Japan.

The nematocidal effect of doramectin was assessed by subcutaneous injection of 200 micrograms/kg (single dosage) in cattle with naturally acquired gastrointestinal nematode infection in Japan. This study consisted of two experiments. In experiment 1, animals were randomly divided into a doramectin group (n = 21) and a non-treated control group (n = 21) by fecal egg count. In experiment 2, another group of ivermectin treatment (n = 12) was prepared in addition to doramectin (n = 23) and control (n = 10) groups, by random assignment as in study 1. After doramectin or ivermectin treatment, the egg count/5 g of feces was measured by the sucrose centrifugal flotation method at intervals of 7 days until Day 21 in experiment 1 and at Days 7, 14, 21, 35, 42, 49 and 63 in experiment 2. Coproculture was also carried out using some of the fecal samples. In the 2 doramectin-treated groups, 96.1%-100% egg reduction rates were obtained for Haemonchus, Cooperia, Mecistocirrus, Trichostrongylus, Ostertagia, Bunostomum, Strongyloides and Trichuris from the 7th day until the 49th day after treatment. Thus doramectin was confirmed to be highly effective against those species of adult nematoda. The effect against Mecistocirrus has not been previously determined. The nematocidal effect against Nematodirus was lower (egg reduction rate approximately 50%) than other species. No adverse reactions to treatment were seen in any animal during either study.

Animals↗
PubMed1995

Morphological, serological and antigenic characteristics, and protein profile of newly isolated Japanese bovine Babesia parasite with particular reference to those of B. ovata.

An intraerythrocytic large protozoan, tentatively designated Babesia sp. 1, was recently isolated from cattle in Hokkaido Prefecture, Japan. This parasite closely resembled B. ovata in shape of piroplasms, but was distinguishable by other morphological, immunological, and biochemical characters. The paired pyriform piroplasm of B. sp. 1 was larger than that of B. ovata. The results from serological and antigenic examination by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis showed that there were cross- but distinguishable-reaction between B. sp. 1 and B. ovata. Protein profiles of both Babesia parasites piroplasms analyzed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) were apparently different from each other. Several major proteins revealed by 2D-PAGE and the immunodominant proteins resolved by Western blot analysis (40 kDa for B. sp. 1 and 29 kDa for B. ovata) were unique to each parasite. The results of the present study indicate the possibility that B. sp. 1 is a species different from B. ovata.

Animals↗
PubMed1995

Effects of growth hormone and insulin-like growth factor I on testosterone secretion in premature male rats.

Present study was planned to clarify the effects of GH and insulin-like growth factor I (IGF-I) on testosterone secretion using premature male rats. Forty rats were divided four groups. GH, IGF-I, both of them or normal saline solution as control were subcutaneously administered to the rats of each group for seven days from 3-week to 4-week of age. After the treatment, six of each group were used to human chorionic gonadotropin (hCG) loading and four to Leydig cell preparation. Serum testosterone responses to hCG loading were significantly higher in 4-week-old rats treated with GH and/or IGF-I for 1 week than in control rats. However, the responses were similar among three treated groups (GH, IGF-I and both). After one-week treatment with GH and/or IGF-I, isolated Leydig cells were prepared from testes of 4-week-old rats and testosterone production by the stimulation of hCG was examined. Amounts of testosterone production stimulated by hCG were significantly greater in the treated rats than in control rats. These findings suggest that GH mediated by IGF-I promotes the testicular responsiveness to gonadotropin on testosterone production in premature rats.

Analysis of Variance↗
PubMed1995

Effects of V1- and V2-vasopressin (AVP) antagonists on the pressor, AVP and atrial natriuretic peptide responses to a hypertonic saline infusion in conscious anephric rats.

To examine the role of vasopressin (AVP) receptors in the regulation of the hemodynamics and release of atrial natriuretic peptide (ANP), and the participation of renal nerve inputs in the osmotic AVP release, hypertonic saline (HS) was infused into conscious, bilaterally nephrectomized rats with non-peptide, selective antagonists for the V1-receptor or V2-receptor of AVP. In the control group, HS alone increased mean arterial pressure, plasma ANP and AVP, plasma volume and plasma osmolality, and decreased the heart rate. In the V1-receptor antagonist group, an increase in the mean arterial pressure and a decrease in heart rate were completely abolished and an increase in plasma ANP was attenuated. In the V2-receptor antagonist group, increases in mean arterial pressure and plasma ANP and a decrease in heart rate were attenuated. However, the ratio of the changes in heart rate to the changes in mean arterial pressure in the V2-receptor antagonist group is significantly higher than that in the control group. In both experimental groups, increases in plasma AVP, plasma volume and plasma osmolality were not different from those in the control group. These results suggest that a HS-induced increase in mean arterial pressure is mediated by the pressor effect of AVP, mainly through V1-receptors, and that the depressor effect of AVP through V2-receptors may not influence tonically HS-induced hypertension. Moreover, HS-induced increase in plasma ANP is mediated mainly by increases in plasma volume and blood pressure, but may not be affected by a direct action of AVP to the heart. Renal afferent nerve inputs may not have effects on the regulation of osmotic AVP release.

Animals↗
PubMed1995

Chlorpropamide-induced ADH release, hyponatremia and central pontine myelinolysis in diabetes mellitus.

Chlorpropamide (CPM) has been reported to produce impaired water excretion due to the enhancement of renal vasopressin (ADH) action and/or due to centrally enhanced ADH release, but it is still unknown whether CPM gives rise to ADH release with a subsequent hyponatremia in diabetes mellitus (DM), which, in turn, causes an impairment of the central nervous system. In 3 patients with DM, who developed hyponatremia during the treatment with CPM, an acute water load (WL) was carried out in the presence and absence of the drug, and plasma ADH was determined with plasma and urine osmolalities. Moreover, in 2 cases, MRI scans of the brain were taken. In all the patients, acute WL tests failed to suppress completely ADH release in response to changes in plasma osmolality in the presence of CPM, which, in turn, resulted in the impaired water excretion. In the absence of CPM, an acute WL normally suppressed plasma ADH leading to the diuresis. MRI scans illustrated the presence of central pontine myelinolysis. It is likely that CPM might stimulate ADH release in DM with a subsequent hyponatremia and brain damages.

Aged↗
PubMed1995

Changes in plasma vasopressin levels and cardiovascular function due to postural changes in diabetic neuropathy.

Decreases in blood pressure are well known to increase the release of vasopressin. Studies were carried out to investigate whether vasopressin responses to postural changes in blood pressure are maintained in diabetic patients with orthostatic hypotension [DM-OH(+)] as well as non-diabetic patients with orthostatic hypotension [nonDM-OH(+)] and these responses were compared with those observed in normal subjects and diabetic patients without orthostatic hypotension [DM-OH(-)]. After 30 min in the supine position, the upright posture for 40 min was maintained and then the supine for 10 min. Blood pressure and heart rate (HR) were measured every 5 min and plasma vasopressin levels (plasma AVP) were determined every 10 min. In normal subjects and DM-OH(-), mean arterial blood pressure (MABP) did not change, but HR increased significantly by the upright position. Plasma AVP did not change in these groups. On the other hand, in DM-OH(+) MABP fell abruptly and remained to decrease during the upright posture. The HR responses in this group, however, were similar to those in normal control and DM-OH(-). Plasma AVP in DM-OH(+) significantly increased only at 30 min during upright. These increases were significantly greater than those in normal and DM-OH(-). There were significant correlation in changes in MABP (delta MAP) and plasma AVP (delta AVP) in DM-OH(+) (delta AVP = -0.13 MABP + 1.5, r = -0.32, p < 0.01). Relationship between delta MABP and delta AVP in nonDM-OH(+) was similar to that in DM-OH(+). It is concluded that AVP responses to orthostatic hypotension in diabetic and non-diabetic neuropathies were attenuated, but heart rate responses in these patients ware well reserved.

Adult↗
PubMed1995

Role of atrial natriuretic peptide in interleukin 1 beta-induced natriuresis in conscious rats.

To assess whether atrial natriuretic peptide (ANP) plays a role in the natriuresis induced by interleukin 1 beta (IL-1 beta), the following experiments were carried out. Experiment (Ex) I: IL-1 beta (7.5 micrograms/kg BW) was given intravenously (i.v.) in conscious hydrated rats (n = 6). Plasma ANP, vasopressin (AVP) osmolality (Posm), Na and K, urine Na (UNa V) and K excretion (UK V), osmolality and flow (UF), and mean arterial blood pressure (MABP) and heart rate were simultaneously determined. In the control group (n = 6), the drug was omitted, and the same protocols were carried out. Ex II: Three mg/kg BW of the specific ANP antagonist, HS-142-1 (HS), was administered i.v. and then, IL-1 beta (7.5 micrograms/kg BW) was given i.v. (n = 6). In the HS alone group (n = 6), IL-1 beta was omitted. The experimental protocols were the same as those in Ex I. IL-1 beta increased significantly plasma ANP and AVP and UNa V, but not UF, accompanied by decreases in Posm and UKV and increases in MABP (ExI). HS inhibited the natriuresis mediated by IL-1 beta, despite increases in plasma ANP and had no influence on plasma AVP and MABP. In the control (ExI) and HS alone (ExII) groups, these parameters did not change, except for decreases in Posm in both groups and increased plasma ANP in the latter. These results suggest that plasma ANP may play an essential role in the IL-1 beta-mediated natriuresis.

Animals↗