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M Ohta

Publications and source records attributed to M Ohta.

At least 217 records · Page 12Linked to original sources
PubMed1999

Pathological effect of synthetic cereulide, an emetic toxin of Bacillus cereus, is reversible in mice.

Cereulide is the causative toxin of the emetic type of food-borne illness caused by Bacillus cereus. This toxin was previously shown to be associated with fulminant liver failure in a human case. Mice were injected i.p. with synthetic cereulide and the development of histopathological changes was examined. Hepatocytes showed mitochondrial swelling with loss of cristae, and dose-dependent increase of small fatty droplets. These microsteatotic hepatocytes were distributed mainly in the pericentral area. At higher cereulide doses, massive degeneration of hepatocytes occurred. The serum values of hepatic enzymes were highest on days 2-3 after the inoculation of cereulide, and rapidly decreased thereafter. General recovery from the pathological changes and regeneration of hepatocytes was observed after 4 weeks.

Animals↗
PubMed1999

Emergence of fosfomycin-resistant isolates of Shiga-like toxin-producing Escherichia coli O26.

We evaluated the susceptibilities of 129 Shiga-like toxin-producing Escherichia coli (STEC) isolates to various antibiotics. The numbers of isolates for which MICs were high (> or = 128 micrograms/ml) were as follows: 5 for fosfomycin, 14 for ampicillin, 1 for cefaclor, 6 for kanamycin, 22 for tetracycline, and 2 for doxycycline. For two isolates of STEC O26 MICs of fosfomycin were high (1,024 and 512 micrograms/ml, respectively). Conjugation experiments and glutathione S-transferase assays suggested that the fosfomycin resistance in these isolates was determined not by a plasmid but chromosomally. The amount of active intracellular fosfomycin in these STEC isolates was 100- to 200-fold less than that in E. coli C600 harboring pREFTT47B408 in the presence of either L-alpha-glycerophosphate or glucose-6-phosphate. Cloning, sequencing, and Northern blot analysis demonstrated that the transcriptional level of the murA gene encoding UDP-N-acetylglucosamine enolpyruvoyl transferase in these isolates was greater than that in E. coli C600. Our results suggest that the fosfomycin resistance in these STEC isolates is due to concurrent effects of alteration of the glpT and/or uhp transport systems and of the enhanced transcription of the murA gene.

Alkyl and Aryl Transferases↗
PubMed1999

Streptococcal pyrogenic exotoxin F (SpeF) causes permeabilization of lung blood vessels.

Acute respiration distress syndrome (ARDS) is a typical complication in toxic shock-like syndrome (TSLS) caused by Streptococcus pyogenes. An isolated perfused rat lung model was used to identify the causative agent of ARDS in TSLS in this study. Some crude preparations separated from the culture supernatants of S. pyogenes isolates caused rapid increases in the weight of perfused lungs, indicating vascular permeabilization. Six samples from M type 1 and 3 isolates from TSLS and pharyngitis patients showed strong permeabilization activity, whereas preparations from isolates of other M types (although the number of isolates examined was limited) were negative. The active substance was purified to a single band by sodium dodecyl sulfate-polyacrylamide gel electrophoresis using various columns, and the N-terminal amino acid sequence was determined. The resultant sequence of eight amino acids was identical to SpeF (mitogenic factor). Moreover, the vascular permeabilization activity of the purified band was abolished with anti-SpeF antiserum prepared by immunizing with the purified SpeF. This activity was also neutralized by the antiserum prepared by immunizing with a synthetic peptide derived from the published SpeF sequence. These results suggested that streptococcal SpeF is a major cause of permeabilization of lung blood vessels and sufficient for the pathogenesis of ARDS under the conditions of TSLS caused by S. pyogenes.

Animals↗
PubMed1999

Molecular characterization of type-specific capsular polysaccharide biosynthesis genes of Streptococcus agalactiae type Ia.

The type-specific capsular polysaccharide (CP) of a group B streptococcus, Streptococcus agalactiae type Ia, is a high-molecular-weight polymer consisting of the pentasaccharide repeating unit 4)-[alpha-D-NeupNAc-(2-->3)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1- ->3 )]-beta-D-Galp-(1-->4)-beta-D-Glcp-(1. Here, cloning, sequencing, and transcription of the type Ia-specific capsular polysaccharide synthesis (cps) genes and functional analysis of these gene products are described. A 26-kb DNA fragment containing 18 complete open reading frames (ORFs) was cloned. These ORFs were designated cpsIaA to cpsIaL, neu (neuraminic acid synthesis gene) A to D, orf1 and ung (uracil DNA glycosylase). The cps gene products of S. agalactiae type Ia were homologous to proteins involved in CP synthesis of S. agalactiae type III and S. pneumoniae serotype 14. Unlike the cps gene cluster of S. pneumoniae serotype 14, transcription of this operon may start from cpsIaA, cpsIaE, and orf1 because putative promoter sequences were found in front of these genes. Northern hybridization, reverse transcription-PCR, and primer extension analyses supported this hypothesis. DNA sequence analysis showed that there were two transcriptional terminators in the 3' end of this operon (downstream of orf1 and ung). The functions of CpsIaE, CpsIaG, CpsIaI, and CpsIaJ were examined by glycosyltransferase assay by using the gene products expressed in Escherichia coli JM109 harboring plasmids containing various S. agalactiae type Ia cps gene fragments. Enzyme assays suggested that the gene products of cpsIaE, cpsIaG, cpsIaI, and cpsIaJ are putative glucosyltransferase, beta-1, 4-galactosyltransferase, beta-1,3-N-acetylglucosaminyltransferase, and beta-1,4-galactosyltransferase, respectively.

Bacterial Capsules↗
PubMed1999

A novel gene required for rhamnose-glucose polysaccharide synthesis in Streptococcus mutans.

Gene rgpG is required for biosynthesis of rhamnose-glucose polysaccharide (RGP) in Streptococcus mutans. Its deduced amino acid sequence had similarity to WecA, which initiates syntheses of enterobacterial common antigen and some O antigens in Escherichia coli. Gene rgpG complemented a wecA mutation of E. coli, suggesting that rgpG may function similarly in RGP synthesis.

Cloning, Molecular↗
PubMed1999

A case of hereditary ceruloplasmin deficiency with iron deposition in the brain associated with chorea, dementia, diabetes mellitus and retinal pigmentation: administration of fresh-frozen human plasma.

We report a familial case of hereditary ceruloplasmin deficiency (HCD) showing an A-G transition in intron 6 of the ceruloplasmin gene. Clinical features consisted of chorea, cerebellar ataxia, dementia, diabetes mellitus, retinal pigmentation and iron deposition in the liver and brain without copper overload in those organs. The patient's children and siblings had similar laboratory results, but did not show any neurological abnormalities. She was medicated for diabetes mellitus at 43 years of age, and neurological signs appeared when she was 52 years old. The laboratory findings were anemia, low concentrations of iron and copper in serum and of copper in urine. Ceruloplasmin was not detected in the serum. The iron and copper contents in the liver were 3,580 and 10 microg/g wet tissue, respectively. MRI of the brain showed iron deposition in the basal ganglia, dentate nucleus and thalamus. This case did not show any abnormal increase in copper in the blood and urine following CuSO(4)5H(2)O oral overloading test. Following the intravenous administration of commercially available fresh-frozen human plasma (FFP) containing ceruloplasmin, the serum iron content increased for several hours due to ferroxidase activity of ceruloplasmin. In the liver, the iron content decreased more with the combined intravenous administration of FFP and deferoxamine than with FFP administration alone. Her neurological symptoms improved following repetitive FFP treatment.

Blood Component Transfusion↗
PubMed1999

Effects of caffeine on the bones of aged, ovariectomized rats.

Caffeine is a substance which many people consume in their daily life. Caffeine's effects on bone are still controversial. Using ovariectomized rats, the present study was conducted to determine to what extent caffeine intake affects the mechanical properties, bone minerals and histology. Aged rats were divided into 2 groups after ovariectomy. Group 1 was fed a 20% protein diet as a control, and group 2 was fed a 20% protein diet supplemented with caffeine (2 mg/100 g body weight). The respective diets were fed to the rats of each group for 90 days. Rats were then killed by heart puncture, blood was collected, and femurs were removed. In 1 group of femurs paraffin cross-sections were made at the midshaft of each bone. Total width, cortical width, total cross-sectional bone area of the midshaft, and the number of osteocytes in randomly selected areas were measured. Another group of bones was subjected to three-point bending testing until failure. Bones were then pulverized and Ca, P, Mg, Zn, Sr, Si, hydroxyproline and hexosamine contents and crystallite size were measured. Various mechanical properties, except modulus of elasticity, in the caffeine group were consistently 7-23% lower than the noncaffeine controls. Yield strain in the caffeine group was significantly less than in the noncaffeine controls. Zinc, Sr, and crystallite size of bone showed a significant decrease in the caffeine group, whereas Si contents significantly increased. Our current results indicate that routine intake of caffeine in the elderly should be regarded with some caution.

Aging↗
PubMed1999

Effect of fluoride concentration and pH on corrosion behavior of titanium for dental use.

Titanium is used as a metal for biocompatible materials such as dental implants or restorations because of its excellent chemical stability. However, the corrosion of Ti in the prophylactic fluoride-containing environment can become problematic. To clarify the effects of fluoride concentration and pH on the corrosion behavior of Ti, we conducted anodic polarization and immersion tests in NaF solution of various concentrations and pH values. The concentrations of dissolved Ti in the test solutions were analyzed by inductively coupled plasma mass spectroscopy. There were obvious limits of fluoride concentration and the pH value at which the corrosion behavior of Ti changed. The corrosion of Ti in the solution containing fluoride depended on the concentration of hydrofluoric acid (HF). When the HF concentration in the solution was higher than about 30 ppm, the passivation film of the Ti was destroyed. The results of this study revealed a relation between the fluoride concentrations and pH values at which Ti corrosion occurred and provided data on such corrosion in environments where the fluoride concentration and pH value are known.

Corrosion↗
PubMed1999

Synthesis of the selective 5-hydroxytryptamine 4 (5-HT4) receptor agonist (+)-(S)-2-chloro-5-methoxy-4-[5-(2-piperidylmethyl)-1,2,4-oxadiazol-3-y l]aniline.

In a search for novel 5-hydroxytryptamine 4 (5-HT4) agonists focusing on the linker group of benzamide derivatives, 2-chloro-5-methoxy-4-[5-(2-piperidylmethyl)-1,2,4-oxadiazol-3-yl]a niline (2) was prepared and its optical isomers were separated. The S isomer 2(S) showed high affinity for the human 5-HT4 receptor without affinity for the human 5-HT3 receptor, and potent 5-HT4 agonistic activity in longitudinal muscle myenteric plexus (LMMP) preparations of guinea pig ileum. The R isomer 2(R) showed opposite selectivity. As a result of other receptor binding studies, 2(S) (YM-53389) was shown to be a highly selective 5-HT4 agonist.

Aniline Compounds↗
PubMed1999

Glucocorticoidal regulation of pituitary vasopressin content in rats.

Although glucocorticoids are known to attenuate vasopressin (AVP) secretion, it is still controversial whether glucocorticoids act on the hypothalamo-neurohypophysial system. We report here glucocorticoidal regulation of pituitary AVP content, which is a specific indicator for the system. The hypothalamic AVP mRNA content and the pituitary AVP content were measured in rats given dexamethasone (2 mg/kg, 2 times over the course of 5 d) or the glucocorticoid receptor antagonist RU-38486 (20 mg/kg, 3 times over the course of 3 d) during euhydration or dehydration. In dexamethasone-treated rats, both the hypothalamic AVP mRNA content and pituitary AVP content decreased after dehydration. In contrast, in the RU-38486 group the hypothalamic AVP mRNA content and pituitary AVP content increased in both euhydrated and dehydrated rats. These results suggest that glucocorticoids may act on hypothalamo-neurohypophysial vasopressinergic system and attenuate its activity under both basal and dehydrated states.

Actins↗
PubMed1999

DNA polymorphism of srRNA gene among Eimeria tenella strains isolated in Japan.

DNA polymorphism in twelve starains of Eimeria tenella isolated from various places in Japan was examined using 1.l kb small subunits ribosomal RNA amplified by PCR. Genetic variation was evaluated by random amplification of polymorphic DNA (RAPD) analysis. DNA fingerprint patterns were grouped into two, indicating that at least two DNA polymorphisms exist in Japanese E. tenella strains.

Animals↗
PubMed1999

Growth hormone advances spermatogenesis in premature rats treated with gonadotropin-releasing hormone agonist.

To clarify the effect of GH on the development of seminiferous tubules in premature male rats, we investigated whether GH accelerates spermatogenesis under the condition of gonadotropin deprivation. Male Wistar rats aged three weeks were divided into three groups and subjected to administration of either long-acting GnRH agonist (GnRHa) or a combination of GnRHa and rat GH, with normal saline solution as control. After the 4-week treatment, sperm density and motility in the right epididymis were measured and seminiferous tubules of right testes were histologically examined. Sperm density and motility were significantly higher in GnRHa+GH-treated rats than in GnRHa-treated rats. In histological examination, the numbers of germ cells in various stages were increased in GnRHa+GH-treated rats compared with GnRHa-treated rats, with the number of mature spermatid being noticeably higher in GnRHa+GH-treated rats. These results suggest that administration of GH decreases loss of germ cells at various stages of spermatogenesis under the condition of gonadotropin withdrawal.

Analysis of Variance↗
PubMed1999

Isolation of two novel alternative splicing variants of allograft inflammatory factor-1.

Allograft inflammatory factor-1 (AIF-1) was initially cloned from rat cardiac allografts undergoing chronic rejection. AIF-1, possessing an EF-hand-like motif, is thought to be a Ca2+ binding protein. In this study, we identified two novel alternatively spliced variants of AIF-1 by reverse-transcription polymerase chain reaction. One variant encodes an AIF-1 protein that lacks 14 amino acids corresponding to one exon. The other variant encodes a truncated AIF-1 protein due to a frameshift introduced by an 85-bp insertion, and its C-terminal region differs from that of AIF-1. Interestingly, these variants have incomplete and no EF-handlike motifs, respectively. The expression level of the latter variant is high in peripheral blood leukocytes, and it is selectively expressed in macrophage-like cell lines.

Alternative Splicing↗
PubMed1999

Developmental alterations in the alpha-fetoprotein sugar chain in maternal serum analyzed by lectin affinity electrophoresis.

Our purpose was to investigate developmental alterations of human alpha-fetoprotein (AFP) oligosaccharides in maternal serum by lectin affinity electrophoresis and to compare the AFP glycoforms in maternal serum with those in umbilical cord serum and amniotic fluid. AFP glycoforms were separated by affinity electrophoresis with concanavalin A (Con A), lentil lectin (LCA), erythroagglutinating phytohemagglutinin (E-PHA) and Allomyrina dichotoma lectin (allo A) and detected by sensitive antibody affinity blotting. In maternal serum, increased proportions of Con A-nonreactive AFP (AFP-C1), LCA strongly-reactive AFP (AFP-L3) and E-PHA-reactive AFP (AFP-P4 and AFP-P5) decreased gradually during the early gestational weeks. Allo A-nonreactive AFP (AFP-A1 and asialo-AFP) were found only in amniotic fluids during early gestational weeks. The percentages of these glycoforms at full term were almost the same among those body fluids. Since the glycoforms of maternal serum AFP were close to those of umbilical cord serum AFP, lectin-affinity electrophoretic analysis of maternal serum AFP may be useful for evaluating the developmental state of fetus by examining the nature of AFP sugar chain.

Amniotic Fluid↗
PubMed1999

Combined effects of caffeine and prostaglandin E2 on the proliferation of osteoblast-like cells (UMR106-01).

BACKGROUND: The general public widely consumes caffeine (1,3,7-trimethylxanthine), which is contained in various foods, beverages and over-the-counter medications. We have shown previously that caffeine intake could affect bone metabolism in vivo. METHODS: Because prostaglandin E2 (PGE2) is shown to be elevated in the periodontally diseased site, the possible interaction between caffeine and PGE2 was investigated in the present study using UMR106-01 rat osteoblast-like cells in vitro. RESULTS: Although neither 0.1 mM caffeine nor 0.1 microg/ml of PGE2 alone showed any inhibitory effects on cell proliferation, the combination of caffeine and PGE2 showed significant inhibition. However, in order to have inhibitory effects, both caffeine and PGE2 had to be present at least 72 or 96 hours in the medium. Addition of the endogenous PGE2 synthesis inhibitor, indomethacin, showed no effects on cell proliferation. Neither cAMP-inducing agent IBMX (0.01 mM and 0.1 mM) nor forskolin (0.001 mM) inhibited cell proliferation, but combined with PGE2 these agents strongly inhibited proliferation as was observed with the combination of caffeine and PGE2, suggesting possibly that the increase of intracellular cAMP concentration plays an important role in the inhibitory effects of cell proliferation. CONCLUSIONS: The present data for the first time demonstrate the possible implication of routine caffeine intake in the acceleration of pathological conditions of periodontitis. Thus, we propose that chronic caffeine intake is one of the possible risk factors in the advancement of pathology in the periodontitis patient. Further research in this area is warranted.

1-Methyl-3-isobutylxanthine↗
PubMed1999

[Clinical characteristics of polycythemia vera in the elderly].

Of 43 elderly patients who were suspected to have polycythemia between October 1990 and July 1998, 12 patients showed an increased red cell volume measured by 51Cr-labeled red blood cells. We analyzed the clinical characteristics of the 12 patients consisted of 7 men and 5 women, with a median age of 71 (range: 57-92). Chief complaints were headaches and dizziness (3 cases), symptoms of other conditions than polycythemia (4 cases). Five patients had no symptoms. Five of 6 patients over 70 years old had no symptoms due to polycythemia. Seven cases (58%) showed splenomegaly and three cases (25%) showed hepatomegaly. Laboratory findings were as follows: WBC 9.7 +/- 3.9 x 10(3)/microliter (mean +/- SD, p < 0.02 vs normal control), Hb 17.9 +/- 4.2 g/dl (p < 0.001), Plt 39.7 +/- 26.0 x 10(4)/microliter, EPO 13.8 +/- 5.2 mU/ml (p < 0.0001), NAP score 258 +/- 114, Vit. B12 1,686 +/- 2,156 pg/ml, arterial O2 saturation more than 92% in all cases. The diagnosis of all cases was polycythemia vera according to the diagnostic criteria of Polycythemia Vera Study Group. Associated conditions included 8 cases of thrombosis (cerebral thrombosis 4, thrombophrebitis 2, myocardial infarction 1, ischemic colitis 1) and 3 cases of malignancy (esophageal cancer 1, breast cancer 1, renal cancer 1), none of which was therapy-related cancer. Six patients (50%) had only phlebotomy, three (25%) only chemotherapy, and three (25%) both phlebotomy and chemotherapy. Patients over 80 years old needed neither intensive nor continuous treatment. Only one patient died due to esophageal cancer at age 89.

Aged↗