Biomedical subjects

S Ohta

Publications and source records attributed to S Ohta.

At least 145 records · Page 8Linked to original sources

PubMed2000

Adsorption and pharmacokinetics of cyclosporin A in relation to mode of infusion in bone marrow transplant patients.

Two main factors that affect the pharmacokinetics of cyclosporin A (CsA) during 24-h durable intravenous (DIV) administration have been reported, namely physiological changes after bone marrow transplantation, and blood sampling through indwelling lines. In addition, it has been found that infusion sets made of polyvinyl chloride (PVC) markedly adsorb CsA. We conducted in vitro adsorption studies of CsA on infusion sets, and the administration routes that are used in the treatment of patients with bone marrow transplantation. We also examined the effects of administration route on CsA pharmacokinetics in clinical practice. The in vitro adsorption study using 30-mm segments of lumen from commercially available infusion sets showed that the degree of CsA adsorption per area of lumen made of PVC was significantly higher than that in those made of polyethylene (PE) or polybutadiene (PB), which showed no adsorption of CsA. Due to its adsorption, use of infusion sets made of PVC resulted in about a 40-50% loss of CsA dose, which affected the pharmacokinetic parameters during 24-h DIV, while those made of PE and PB did not. The use of non-PVC infusion sets should allow for accurate monitoring of CsA results, and provide cost benefit in the treatment of bone marrow transplantation.

Adsorption↗

PubMed2000

Sequential analysis of HLA-C-specific killer cell inhibitory receptor (CD158b) expressing peripheral blood mononuclear cells during chronic graft-versus-host disease.

We have sequentially investigated the expression of natural killer cell inhibitory receptors (KIRs) for HLA-C (CD158b) on peripheral blood mononuclear cells (PBMC) in three patients with extensive chronic graft-versus-host disease (cGVHD) after allogeneic bone marrow transplantation (alloBMT). Clinical symptoms of cGVHD were not cured and worsened in the first patient whose CD158b-positive cells increased to 18.5% during cGVHD and decreased to 9.4% at 8 months after transplantation. On the other hand, cGVHD was cured and did not relapse in the second patient whose CD158b-positive cells increased up to 45.9% during cGVHD and sustained 19.4% at 8 months after transplantation. In contrast, CD158b-positive cells were less than 10% during the course of cGVHD in the third patient, and her cGVHD did not respond to treatment. Therefore, it appears that chronic allostimulation augments the expansion of CD158b-positive cells and these expanded CD158b-positive cells may have some role in the control of alloresponse in some patients.

Adult↗

PubMed2000

Expression of HLA-C-specific natural killer cell receptors (CD158a and CD158b) on peripheral blood mononuclear cells after allogeneic bone marrow transplantation.

We investigated the expression of natural killer cell receptors (NKRs) for HLA-C on peripheral blood mononuclear cells (PBMCs) in 23 allogeneic bone marrow transplantation (allo-BMT) patients to analyse the role of NKRs in alloresponse concerning graft-versus-host disease (GVHD). CD158a expression was low and there was little change in the expression after allo-BMT. Also, there was no difference in the proportion of CD158a+/CD3- after allo-BMT. In contrast, the proportion of CD158b+/CD3- cells, mainly NK cells, increased in the early stage (< 2 months) after allo-BMT and then gradually decreased (3.3 +/- 2.6% before BMT vs. 15.4 +/- 8. 6% in the early stage after BMT, 8.5 +/- 4.9% during the period 3-6 months after BMT and 7.0 +/- 3.0% > 6 months after BMT; P < 0.05). However, CD158b expression on CD3+ T cells increased 3 months after allo-BMT (1.1 +/- 1.1% before BMT vs. 5.1 +/- 7.7% during the period 3-6 months after BMT and 3.0 +/- 2.4% > 6 months after BMT, P < 0. 05). The highest percentages of CD158 expression in patients without chronic GVHD (cGVHD) and those with cGVHD were compared. The percentage of CD158b+/CD3+ cells and also that of CD158b+/CD8+ cells were significantly increased in patients with cGVHD compared with those in patients without cGVHD (2.6 +/- 2.0% vs. 8.0 +/- 11.2% and 2.3 +/- 1.5% vs. 8.3 +/- 11.7% respectively; P < 0.05). The exact clinical relevance of these CD158b-expressing cells is not clear. However, there is an interesting possibility that CD158b-expressing cells play some role in the regulation of GVHD after allo-BMT.

Bone Marrow Transplantation↗

PubMed2000

Bacterial cell death induced by human pro-apoptotic Bax is blocked by an RNase E mutant that functions in an anti-oxidant pathway.

BACKGROUND: Bax is a member of the Bcl-2 family and induces apoptosis of mammalian cells. We have shown that a trace amount of human Bax induces the cell death of Escherichia coli, accompanied by damage to DNA, and that the region of Bax which is lethal to E. coli is also responsible for apoptosis-inducing activity in the mammalian cells. RESULTS: We isolated a Bax-resistant mutant from E. coli cells that survive in the presence of paraquat, a generator of superoxide, by screening a library constructed from the random insertion of a transposon. Psb1 (paraquat-resistant, suppressor of Bax-1) mutant had a Tn 10 transposon inserted in the rne gene of E. coli, splitting the RNase E gene (rne) into N- and C-terminal halves. The introduction of the truncated 5' end of rne specifically enhanced resistance to paraquat, prevented cell death induced by Bax and decreased the intracellular H2O2 concentration. The region responsible for the paraquat- and Bax-resistance was not the catalytic site for the endoribonuclease activity of RNase E. CONCLUSIONS: The N-terminal region of the RNase E protein inhibits bacterial death induced by human Bax as well as paraquat through a unique mechanism that is distinct from RNA digestion. This study implies that the protection of bacterial death induced by Bax is associated with an anti-oxidant pathway and that a mutant RNase E has a novel function as an anti-oxidant.

Apoptosis↗

PubMed2000

The evolution of C4 plants: acquisition of cis-regulatory sequences in the promoter of C4-type pyruvate, orthophosphate dikinase gene.

In a previous study, we identified the C4-like pyruvate, orthophosphate dikinase gene (Pdk) in the C3 plant rice, with a similar structure to the C4-type Pdk in the C4 plant maize. In order to elucidate the differences between C4-type and C4-like Pdk genes in C4 and C3 plants, we have produced chimeric constructs with the beta-glucuronidase (GUS) reporter gene under the control of the Pdk promoters. In transgenic rice, both rice and maize promoters directed GUS expression in photosynthetic organs in a light-dependent manner. However, the maize promoter exhibited a much higher transcriptional activity than the rice promoter did. These results indicate that the rice C4-like Pdk gene resembles the maize C4-type Pdk gene in terms of regulation of expression. We also tested the activity of the rice promoter in transgenic maize. GUS activity was seen in both photosynthetic and non-photosynthetic organs. Thus, the rice promoter does not confer a strict organ-specific gene expression, as the maize promoter does. Moreover, the rice promoter directed GUS expression not only in mesophyll cells but also in bundle sheath cells, whereas the maize promoter directed expression only in mesophyll cells. Taken together, the results obtained from both transgenic maize and rice demonstrate that the rice and maize promoters differ not only quantitatively, but also qualitatively, in terms of their cell- and organ-specificity. Experiments with swapped promoters using the rice and maize promoters further demonstrated that a limited sequence region from -330 to -76 of the maize promoter confers light-regulated, high-level expression to the rice promoter in maize mesophyll protoplasts. We conclude the gain of cis-acting elements conferring high-level expression and mesophyll cell specificity was necessary for establishment of a C4-type Pdk gene during the course of evolution from C3 to C4 plants.

Evolution, Molecular↗

PubMed2000

Reduction of hydroxamic acids to the corresponding amides catalyzed by rabbit blood.

1. The hydroxamic acids N-hydroxyphenacetin and N-hydroxy-2-acetylaminofluorene were reduced to the corresponding amides, phenacetin and 2-acetylaminofluorene respectively by rabbit blood supplemented with both NAD(P)H and FAD. These reducing activities were found in erythrocytes but not in plasma, and were sensitive to inhibition by carbon monoxide and oxygen. When blood or erythrocytes were boiled, these activities were not abolished. 2. Haemoproteins such as haemoglobin and catalase exhibited the reductase activity in the presence of both NAD(P)H and FAD under anaerobic conditions. The activity was not abolished when the haemoproteins were boiled. 3. Haematin showed a significant reducing activity in the presence of these cofactors. The activity of haematin was also observed with the photochemically reduced form of FAD. 4. The reduction system in blood was composed of NAD(P)H, FAD and haemoglobin. Reduction appears to proceed in two steps, i.e. the reduction of FAD by NADH or NADPH, followed by the non-enzymatic reduction of the hydroxamic acids to the amides by reduced FAD, catalyzed by the haem group of haemoglobin in rabbit erythrocytes.

2-Acetylaminofluorene↗

PubMed2000

Reduction of stilbene oxide and styrene oxide to the corresponding alkenes by intestinal bacteria.

1. This study provides the first evidence that stilbene oxide and styrene oxide are reductively metabolized to the corresponding alkenes by intestinal bacteria in animals. 2. When trans- or cis-stilbene oxide were incubated with the caecal contents of rat under anaerobic conditions, both trans- and cis-stilbene were isolated from the incubation mixture. Styrene oxide was also reduced to styrene by rat caecal contents. 3. Caecal contents of mouse, hamster and guinea pig also exhibited alkene oxide reductase activities toward cis- and trans-stilbene oxides, and styrene oxide. In contrast, liver microsomes or cytosol exhibited no epoxide reductase activities toward these substrates. 4. Seven pure strains of intestinal bacteria exhibited alkene oxide reductase activities of varying degrees under anaerobic conditions, with the highest activity being observed in Clostridium sporogenes. 5. Cell-free extracts of either the intestinal bacteria in rat caecal contents or C. sporogenes exhibited reductase activity when supplemented with both NAD(P)H and FMN under anaerobic conditions. Reductase activity was also observed on addition of the photochemically reduced form of FMN instead of both NAD(P)H and FMN.

Animals↗

PubMed2000

The promoter for the maize C4 pyruvate, orthophosphate dikinase gene directs cell- and tissue-specific transcription in transgenic maize plants.

The pyruvate,orthophosphate dikinase (PPDK) gene coding the chloroplast enzyme involved in C4 photosynthesis has a dual promoter system. The first promoter is responsible for the transcription of a larger transcript and its product is targeted to the chloroplast (hence, it is designated as C4Pdk promoter) while the second promoter is responsible for the transcription of a smaller transcript and its product remains in the cytosol. In this study, chimeric maize C4Pdk promoter (0.9 or 1.5 kb)-beta-glucuronidase or luciferase fusion genes were introduced into maize plants by Agrobacterium-mediated transformation. The cell- and tissue-specificities of the maize C4Pdk promoter in the transgenic maize plants were examined by histochemical and enzymic activity analyses of the reporters in different photosynthetic cells and tissues. The results showed that the reporter proteins are almost exclusively localized in leaf mesophyll cells. Among the tissues tested, leaf blade had the highest reporter activities with sheath exhibiting about 10% of the activities in blade. Husk, stem, tassel and root had no or very little reporter activities. Taken together, these results suggest that the maize C4Pdk promoter is specifically transcribed in the mesophyll cells of leaf blade and to a much less extent in the mesophyll cells of sheath, but not in leaf bundle sheath cells or other tissues. Furthermore, the 0.9 kb maize C4Pdk promoter sequences appear to contain the necessary cis-acting elements for its cell- and organ-specific expression.

Gene Expression Regulation, Enzymologic↗

PubMed2000

Antinociception by epidural and systemic alpha(2)-adrenoceptor agonists and their binding affinity in rat spinal cord and brain.

UNLABELLED: This study was designed primarily to relate the antinociceptive and hemodynamic effects of clinically available alpha(2)-adrenoceptor agonists to their binding affinity for alpha(2)-adrenoceptors in the spinal cord and brain. In rats with chronic indwelling epidural catheters, the percentage maximal possible effect on tail-flick latency was measured after epidural or IM dexmedetomidine (DXM), clonidine (CL), or tizanidine (TZ) administration. To examine their binding affinities, isolated spinal cord and brain membranes with an alpha(2) agonist were incubated with (3)H-UK14304, a selective alpha(2) agonist, and the radioactivity in the reaction mixtures was measured by liquid scintillation spectrometry. Epidural DXM (0.5-10 microg), CL (10-500 microg), and TZ (5-500 microg) all produced dose-dependent antinociceptive effects; the rank order of potencies was DXM > CL > TZ, the same as for their systemic administration. The antinociceptive effects were blocked by epidural yohimbine. The receptor binding affinities expressed as the concentration that inhibits 50% for spinal cord and brain, respectively, were 0.25 and 1.3 nM (DXM), 10.8 and 12.5 nM (CL), and 48.2 and 96.8 nM (TZ). The changes in arterial blood pressure and heart rate evoked by antinociceptive doses did not correlate with the rank order of antinociceptive potencies. The relative antinociceptive potencies of epidural alpha(2) agonists may depend on their binding affinities to alpha(2)-adrenoceptors in the spinal cord, but their cardiovascular effects may result from actions both inside and outside the central nervous system. IMPLICATIONS: Spinal antinociception caused by the epidural administration of alpha(2) agonists is well correlated with their binding affinity to spinal alpha(2)-adrenoceptors.

Adrenergic alpha-2 Receptor Agonists↗

PubMed2000

Ibudilast modulates platelet-endothelium interaction mainly through cyclic GMP-dependent mechanism.

3-Isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine (ibudilast) has been widely used in Japanese clinics for its antiasthmatic and antithrombotic effects. We investigated the mechanisms involved in the antiplatelet effects of the agent, specifically focusing on platelet-endothelium interaction. Ibudilast inhibits both phosphodiesterase (PDE) 3 and 5, the two major PDE isoforms of human platelets, with an IC50 of 31 and 2.2 microM, respectively. Cyclic guanosine monophosphate (GMP) accumulation in washed human platelets exposed to ibudilast alone increased significantly only at high concentrations of the agent (100 microM), whereas > or = 1 microM ibudilast enhanced cyclic GMP levels in the platelets cocultured with bovine aorta endothelial cells (ECs). In contrast, ibudilast enhanced cyclic AMP accumulation only at 100 microM, either with or without ECs. The synergistic effect of ibudilast and EC on cyclic nucleotide accumulation also was demonstrated by the inhibitory capability of the drug and the cells on platelet aggregation. The synergism between ibudilast and aspirin-pretreated ECs was more pronounced than that between ibudilast and N(omega)-nitro-L-arginine (L-NNA)-pretreated ECs. Ibudilast affected neither ATP diphosphohydrolase activity nor NO release from EC up to a concentration of 10 microM. We conclude that ibudilast exhibits antiplatelet properties mainly by inhibiting PDE5 to potentiate antiplatelet function of endothelium-derived NO.

Animals↗

PubMed2000

Establishment and characterization of a colonic epithelial cell line MCE301 from transgenic mice harboring temperature-sensitive simian virus 40 large T-antigen gene.

We produced an immortalized colonic epithelial cell line, MCE301, using fetal mice transgenic for the temperature-sensitive simian virus 40 large T-antigen gene. MCE301 cells showed epithelial-like morphology and maintained tight connections with neighboring cells. The cells grew at a permissive temperature (33 degrees C), but the growth of the cells was significantly prevented at the nonpermissive temperature (39 degrees C). The cells expressed large T-antigen at 33 degrees C but not at 39 degrees C. MCE301 cells were not transformed, as judged by the absence of anchorage-independent growth in soft agar gel and lack of tumor formation in nude mice. Electron microscopic studies showed that the cells formed microvilli-like structures on the cell surface and junctional complexes such as tight junctions and desmosomes between the cells. The cells expressed cytosketal (acidic cytokeratins and actin), basement membrane (laminin and collagen type IV) and junctional complex proteins (ZO-1 and desmoplakin I + II), as judged by specific antibodies. Fetal bovine serum, epidermal growth factor, insulin-like growth factor and insulin significantly increased the cell growth at 33 degrees C. Moreover, MCE301 cells expressed colonic mucin Muc2 mRNA as demonstrated by reverse transcriptase-polymerase chain reaction, indicating that the cells originate from mucus-secreting cells. Alkaline phosphatase, a brush border-associated enzyme, was detected in the cells. Sodium butyrate (2 mM), an inducer of cellular differentiation, markedly elevated alkaline phosphatase activity. Thus, the present mouse colonic epithelial cell line MCE301 possessing these unique characteristics should provide a useful in vitro model of colonic epithelium.

Alkaline Phosphatase↗

PubMed2000

Evidence for the degradation of maleate moiety in chlorpheniramine maleate solution using a stability-indicating HPLC method.

The degradation phenomenon of maleate moiety of chlorpheniramine maleate in solution has been demonstrated by means of a peculiar ion-pair HPLC method developed by the authors, which permits the simultaneous determination of chlorpheniramine and maleate. A commercial cough drug containing chlorpheniramine maleate was dissolved in water with m-hydroxybenzoic acid as an internal standard, and then kept for several days at room temperature. It was recognized that the maleate content in the drug solution had gradually decreased, whereas chlorpheniramine content had not decreased. A simple solution of maleic acid was also kept for several days at room temperature, and it was also recognized that the maleate content in the solution preserved at the same concentration as the solution of the commercial cough drug had gradually decreased, and the percent of remaining maleate reached zero. The degraded peaks on HPLC chromatogram were not detected at all by UV detector, and the disappearance of maleate was ascertained by GC-MS. No detectable example of maleate of chlorpheniramine maleate in a commercial cough syrup has suggested that maleate moiety of chlorpheniramine maleate decomposed to carbon dioxide.

Chlorpheniramine↗

PubMed2000

Reductive dimerization of alkylidenemalonates using samarium(II) diiodide and 1H-NMR behavior of the dimers, 2,3-diaryl-1,1,4,4-butanetetracarboxylates.

Alkylidenemalonates were readily dimerized in the presence of SmI2 to give 2,3-disubstituted 1,1,4,4-butanetetracarboxylates as mixtures of meso and racemic isomers in moderate to good yields. The structure of the less polar isomer of tetraethyl 2,3-diphenyl-1,1,4,4-butanetetracarboxylate was determined by X-ray crystallographic analysis to be the meso form. Characteristic 1H-NMR behavior of the meso and racemic isomers is also discussed.

Butanes↗

PubMed2000

Genetic differentiation and post-glacial establishment of the geographical distribution in Aegilops caudata L.

Aegilops caudata L. is a diploid wild relative of wheat distributed over the north-eastern Mediterranean from Greece to northern Iraq. To elucidate the geographical differentiation pattern, 35 accessions derived from the entire distribution area were crossed with four Tester strains. Pollen fertility in the F1 hybrids varied from 0 to 96.3% among cross combinations, closely correlating with the geographical regions where the parental accessions were collected. Based on the intraspecific hybrid sterility, the present distribution area of Ae. caudata was divided into two geographical regions effectively isolated by the mountainous region lying between West Anatolia and Central Anatolia. The western region is composed of Greece and West Anatolia, while the eastern region consists of Central Anatolia, South Anatolia, East Anatolia and northern Iraq. The present results and the facts from recent palaeopalynological works suggest that during the maximum glacial period from 18,000 BP to 16,000 BP, Ae. caudata occurred in the two isolated regions, i.e., the region surrounding the Aegean Sea and the western Levant or some sheltered habitats in the East Taurus/Zagros mountains arc, and that it migrated into Central and East Anatolia from the latter regions as the climate became warmer. Furthermore, it is also suggested that the Levant populations now occur in the eastern region of the distribution, while those occurring in the Aegean Sea region during the last glacial period now occupy the western region of the distribution.

Chromosomes↗

PubMed2000

A new type of glycoglycerolipids from Corynebacterium aquaticum.

A new type of glycoglycerolipids, S361A and S365A, were obtained from Corynebacterium aquaticum strains, S361 and S365, newly isolated from soils, and were identified as (2R)-1-[alpha-glucopyranosyl-(1alpha-3)-(6O-acyl-alpha-manno pyranosyl)]-3-O-acylglycerol and (2R)-1-[alpha-mannopyranosyl-(1alpha-3)-(6-O-acyl-alpha-mannopyran osyl)]-3-O-acylglycerol, respectively. S365A was identical to a novel glycoglycerolipid recently isolated from some bacteria, but S361A was a new analog having a glucosylmannosyl in place of the dimannosyl group. Our results indicate that this sn-2 lysotype of glyceroglycolipids may be widely distributed in bacteria.

Carbohydrate Conformation↗

PubMed2000

Genetic analysis of two female patients with incomplete Denys-Drash syndrome.

Denys-Drash syndrome (DDS) is characterized by genital anomaly, early onset nephropathy and high risk for developing Wilms' tumor (WT). Recently, mutations in exon 8 or 9 of the Wilms' tumor suppressor gene (WT1) have been found in the majority of DDS patients studied. We analyzed these two exons of the WT1 gene in genomic DNA from two female patients with DDS by using polymerase-chain reaction (PCR) and direct sequencing. The patients were accompanied with normal external genitalia, early onset renal failure between 6 and 12 months of age, and unilateral Wilms' tumor. Genomic DNA was isolated from peripheral blood leucocytes of the patients. Amplification of exons 8 and 9 of the WT1 gene by PCR was performed, and direct sequencing of the PCR product was performed using an automatic DNA sequencer. Two heterozygous missense mutations were found in these patients, including a missense mutation in exon 9 at codon 388 replacing the wild-type Cys with Phe, and a previously described mutation in exon 9 at codon 398 replacing the wild-type Leu with Pro. Cys388Phe is a novel mutation in the WT1 gene in the DDS. These cases are considered to be "incomplete DDS" with nephropathy and Wilms' tumor and without genital anomaly, the validity of which has been confirmed by mutation analysis.

Adolescent↗

PubMed2000

Prenatal confirmation of periventricular leukomalacia in a surviving monochorionic-diamniotic twin after death of the other fetus: a case report.

A 30-year-old woman was found to be carrying monochorionic-diamniotic twins at 7 weeks of gestation. The growth-retarded fetus died at 21 weeks of gestation. At 28 weeks of gestation, periventricular leukomalacia was detected in the brain of the surviving fetus by transvaginal ultrasonography. A female baby presenting with microcephaly was born at 39 weeks of gestation, and CT of the brain showed microcephaly and marked hydrocephalus. At 12 months of age, the surviving infant presented with severe physical growth retardation, and frequent episodes of clonic convulsions.

Adult↗

PubMed2000

Preoperative hyponatremia as a clinical characteristic in elderly patients with large pituitary tumor.

This study investigated the pathophysiology of preoperative hyponatremia in elderly patients with a large pituitary tumor. The tumor size, initial symptoms, and preoperative pituitary hormonal function were analyzed in 96 patients, consisting of 82 younger than 70 years old (mean age 49.7 years) and 14 older than 70 years old (mean age 72.0 years). There was no difference in tumor size between the two age groups. The initial symptom of all younger patients was visual disturbance. Preoperative hormonal evaluations revealed subclinical panhypopituitarism in four patients (4.9%). Five of the 14 older patients had severe hyponatremia (107-117 mEq/l) based on panhypopituitarism, and four of these five patients showed consciousness disturbance as the initial symptom, initiated by physical and/or psychological stress, or occurrence of intratumoral hemorrhage. Preoperative subclinical panhypopituitarism was found in another patient. The overall occurrence rate of preoperative panhypopituitarism in the older patients was 42.9%. The difference in the frequency of preoperative panhypopituitarism was statistically significant between the two groups. Preoperative severe hyponatremia associated with a large pituitary tumor is characteristic of elderly patients. The number of receptors for adrenocorticotropic hormone in the adrenal cortex decreases during the aging process. Additional physical and/or psychological stress prompts pituitary dysfunction in such patients, causing the manifestation of acute symptoms of adrenal insufficiency based on panhypopituitarism. Primary care using high dose hydrocortisone and electrolyte fluid is critical.

Adrenal Insufficiency↗