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Biomedical subjects

K Ohashi

Publications and source records attributed to K Ohashi.

At least 55 records · Page 3Linked to original sources
PubMed2001

Tumor necrosis factor alpha and its receptors in experimentally bovine leukemia virus-infected sheep.

To examine whether tumor necrosis factor alpha (TNF alpha) contributes to the pathogenesis of bovine leukemia virus (BLV) infection, the mRNA expression patterns of TNF alpha and its receptors, type 1 (TNF R1) and type 2 (TNF R2) were investigated. Sheep inoculated with BLV were divided into two groups; one was BLV-positive and the other BLV-negative based on the detection in peripheral blood mononuclear cells (PBMC). Expression of TNF R1 mRNA was down-regulated in PBMC from the BLV-positive compared to BLV-negative sheep. No difference was shown in the expression levels of TNF R2 mRNA between the two groups. Furthermore, proliferative responses of PBMC in the presence of TNF alpha were observed from the BLV-positive, but not BLV-negative sheep. Membrane-bound TNF alpha (mTNF alpha) is thought to be one of the ligands, inducing B-cell activation. Flow cytometric analysis demonstrated that the number of PBMC, that were positive for mTNF alpha expression, was increased in the BLV-positive sheep. Thus, the expression of TNF alpha and its receptors may be closely associated with lymphocytosis induced by BLV.

Animals↗
PubMed2001

cDNA cloning, characterization and vaccine effect analysis of Haemaphysalis longicornis tick saliva proteins.

Immunological control of ticks is currently the only sustainable and practical alternative method to the current use of acaricides which has serious limitations. The success of this method is dependent upon identification and cloning of potential tick vaccine antigens. We used a combination of immuno-screening of an adult tick cDNA library as well as the 3 and 5 rapid amplification of cDNA ends to clone two cDNAs, encoding tick saliva proteins from Haemaphysalis longicornis. The two cDNAs herein named HL 34 and 35 are 1000 bp each and encode polypeptides with 292 and 321 amino acid residues respectively. Northern blotting analysis of total RNA from ticks at different feeding stages revealed that expression of both HL 34 and HL35 mRNAs is induced during the slow feeding phase. We speculate that the functions of both genes are closely associated with blood feeding. Expression analysis by RT-PCR showed that both genes are expressed in other tick organs in addition to salivary glands. Recombinant HL 34 was successfully expressed in Escherichia coli and its suitability as a tick vaccine antigen was analyzed in rabbits. We propose that rHL34 could be a useful component of a cocktail tick vaccine.

Amino Acid Sequence↗
PubMed2001

Severe hypercholesterolemia, hypertriglyceridemia, and atherosclerosis in mice lacking both leptin and the low density lipoprotein receptor.

Leptin-deficient mice (ob/ob) are an excellent murine model for obesity, insulin resistance, and diabetes, all of which are components of a multiple risk factor syndrome that, along with hypercholesterolemia, precipitates a potential high risk for atherosclerosis. In the current study, we show an unexpectedly severe hyperlipidemia in ob/ob mice on a background of low density lipoprotein receptor (LDLR) deficiency (-/-). Doubly mutant mice (LDLR-/-;ob/ob) exhibited striking elevations in both total plasma cholesterol (TC) and triglyceride (TG) levels (1715 +/- 87 and 1016 +/- 172 mg/dl, respectively), at age 3-4 months, resulting in extensive atherosclerotic lesions throughout the aorta by 6 months. Lipoprotein analyses revealed the elevated TC and TG levels to be due to a large increase in an apoB-containing broad-beta remnant lipoprotein fraction. While fasting, diet restriction, and low level leptin treatment significantly lowered TG levels, they caused only slight changes in TC levels. Hepatic cholesterol and triglyceride contents as well as mRNA levels of cholesterologenic and lipogenic enzymes suggest that leptin deficiency increased hepatic triglyceride production but did not change cholesterol production in ob/ob mice regardless of their LDLR genotype. These data provide evidence that the hypertriglyceridemia and hypercholesterolemia in the doubly mutant mice are caused by distinct mechanisms and point to the possibility that leptin might have some impact on plasma cholesterol metabolism, possibly through an LDLR-independent pathway. This model will be an excellent tool for future studies on the relationship between impaired fuel metabolism, increased plasma remnant lipoproteins, diabetes, and atherosclerosis.

Animals↗
PubMed2001

Characterization of two cDNAs encoding serine proteinases from the hard tick Haemaphysalis longicornis.

Host vaccination against tick infestation is at present the most practical and sustainable alternative tick control method to the current acaricide use which has serious limitations. However the success of this approach to control ticks depends upon the identification of target vaccine antigens. Members of the serine proteinase gene family may represent an interesting group of proteins to target as candidate antigens because of their involvement in regulation of many physiological functions and development processes in a wide range of organisms. We used RT-PCR with the 3' and 5' RACE to clone two cDNAs encoding full-length serine proteinases from the hard tick, Haemaphysalis longicornis. RT-PCR degenerate primers were designed from amino acid sequences surrounding active sites, His(57) and Ser(195) conserved among most known serine proteinase. Gene specific primers designed from nucleotide sequences of the RT-PCR products were used to prime the 3' and 5' RACE. Southern blotting analysis showed that both HLSG-1 and -2 are single copy. The 2 cDNAs, HLSG-1 and -2 are 1.2 and 1.0 kb long in size with open reading frames encoding polypeptides with 37.7 and 31.2 kDa predicted molecular mass respectively. Northern blotting analysis of total RNA from unfed and partially fed whole ticks showed that the expression of mRNAs for both HLSG-1 and -2 was induced by blood feeding. Expression analysis by RT-PCR showed that both HLSG-1 and -2 are expressed in other tick organs in addition to salivary glands and midguts. The 6 serine proteinase consensus cyteine residues are well conserved in both HLSG-1 and -2. We have discussed our findings with respect to tick vaccine development research.

Amino Acid Sequence↗
PubMed2001

M100907, a selective 5-HT(2A) receptor antagonist, attenuates phencyclidine-induced Fos expression in discrete regions of rat brain.

5-HT and dopamine receptor antagonists have become widely used as atypical antipsychotics. Although 5-HT(2A) receptor antagonistic activity is thought to contribute to the atypical aspects of these agents, the precise mechanism remains unknown. M100907 (R(+)-alpha(2,3-dimethoxyphenyl)-1-[2(4-fluorophenyl)ethyl)]-4-piperidine -methanol), a selective 5-HT(2A) receptor antagonist, is reported to attenuate phencyclidine (PCP)-induced locomotion in rodents. For the purpose of identifying regions in which M100907 exerts its effect, we investigated the effects of M100907 on PCP-induced Fos expression in rat brain. PCP (5 mg/kg, subcutaneously, s.c.) induced Fos expression in the cingulate cortex area 3, the agranular insular cortex, the piriform cortex, the nucleus accumbens, the anterior paraventricular thalamic nucleus and the ventral lateral septal nucleus. Pretreatment with M100907 (0.5 mg/kg, s.c.) attenuated Fos expression induced by PCP in the nucleus accumbens core, the shell, the agranular insular cortex and the piriform cortex. M100907 did not induce Fos expression in any of the regions investigated including the dorsolateral caudate/putamen when given alone. These results indicate that 5-HT(2A) receptor antagonism attenuates Fos expression in a regionally specific manner in rat brain in the PCP model of psychosis.

Animals↗
PubMed2001

Adenovirus is a key pathogen in hemorrhagic cystitis associated with bone marrow transplantation.

Late-onset hemorrhagic cystitis (HC) is a well-known complication of bone marrow transplantation (BMT) that is mainly attributed to infection with BK virus (BKV) and adenovirus (AdV). From 1986 through 1998, 282 patients underwent BMT, and 45 of them developed HC. Urine samples tested positive for AdV in 26 patients, of which 22 showed virus type 11. Among patients who underwent allogeneic BMT, logistic regression analysis revealed acute graft-versus-host disease (grade, > or = 2) to be the most significant predictive factor for HC (P < .0001). In addition, a total of 193 urine samples regularly obtained from 26 consecutive patients who underwent allogeneic BMT were examined for BKV, JC virus (JCV), and AdV by means of polymerase chain reaction. Of patients without HC, approximately 30% of the specimens tested positive for BKV (58 samples) and JCV (55 samples), whereas 5 (3%) tested positive for AdV. Of the 3 samples obtained from patients with HC, the numbers of positive results for BKV, JCV, and AdV were 3, 1, and 1, respectively; the numbers of positive results increased to 14 of 17, 9 of 17, and 10 of 17, respectively, when we added another 14 samples obtained from 14 patients with HC (P < .0001, P = .026, and P < .0001, respectively). In conclusion, there was significant correlation between AdV and HC in the patients we studied.

Adenovirus Infections, Human↗
PubMed2001

Virol A, a toxic trans-polyacetylenic alcohol of Cicuta virosa, selectively inhibits the GABA-induced Cl(-) current in acutely dissociated rat hippocampal CA1 neurons.

The effects of virol A (VA), a toxic component of Cicuta virosa (water hemlock), on the GABA-induced Cl(-) current (I(GABA)) in acutely dissociated rat hippocampal CA1 neurons were investigated using whole-cell patch-clamp techniques. VA reversibly reduced I(GABA) and the muscimol (Mus)-induced current (I(Mus)) in a concentration-dependent manner. The IC(50) values for VA against I(GABA) and I(Mus) were 9.6x10(-7) and 9.8x10(-7) M, respectively. VA shifted the EC(50) value of I(GABA) from 6.5x10(-6) to 2.1x10(-5) M, whereas it had no effect on the maximum response, thereby suggesting that VA inhibited I(GABA) in a competitive manner. VA had no apparent effect on current-voltage relationships for I(GABA), thus indicating the lack of voltage-dependency. On the other hand, application of VA (10(-6) M) did not additionally reduce the I(GABA) suppressed by >10(-5) M picrotoxin. VA but not bicuculline accelerated the decay phase of I(GABA), as was seen with picrotoxin. Moreover, pre-application of 10(-5) M VA reduced I(GABA). VA did not inhibit that induced by glycine (10(-4) M). These results indicate that VA inhibits I(GABA) by acting both on the GABA agonist site and on the Cl(-) channel of the GABA(A) receptor-channel complex. VA is a structurally novel type of compound that selectively inhibits the GABA(A) receptor-Cl(-) channel complexes in mammalian central nervous system neurons.

Animals↗
PubMed2001

Asialoglycoprotein receptor deficiency in mice lacking the major receptor subunit. Its obligate requirement for the stable expression of oligomeric receptor.

The asialoglycoprotein receptor is an abundant hetero-oligomeric endocytic receptor that is predominantly expressed on the sinusoidal surface of the hepatocytes. A number of physiological and pathophysiological functions have been ascribed to this hepatic lectin (HL), the removal of desialylated serum glycoproteins and apoptotic cells, clearance of lipoproteins, and the sites of entry for hepatotropic viruses. The assembly of two homologous subunits, HL-1 and HL-2, is required to form functional, high affinity receptors on the cell surface. However, the importance of the individual subunits for receptor transport to the cell surface is controversial. We have previously generated HL-2-deficient mice and showed that the expression of HL-1 was significantly reduced, and the functional activity as the asialoglycoprotein receptor was virtually eliminated. However, we failed to detect phenotypic abnormalities. To explore the significance of the major HL-1 subunit for receptor expression and function in vivo, we have disrupted the HL-1 gene in mice. Homozygous HL-1-deficient animals are superficially normal. HL-2 expression in the liver is virtually abrogated, indicating that HL-1 is strictly required for the stable expression of HL-2. Although these mice are almost unable to clear asialo-orosomucoid, a high affinity ligand for asialoglycoprotein receptor, they do not accumulate desialylated glycoproteins or lipoproteins in the plasma.

Animals↗
PubMed2001

Superficial esophageal carcinoma: an in vitro study of high-resolution MR imaging at 1.5T.

The purpose of this study was to determine the diagnostic accuracy of high-resolution MR imaging at 1.5T for evaluating the mural invasion of superficial esophageal carcinoma. Forty-one esophageal specimens taken from patients suspected of having superficial carcinoma were studied using a 1.5T MR system with a surface coil. Spin-echo MR images were obtained with a field of view of 50mm, matrix of 256 x 256, and section thickness of 2mm (voxel size = 0.08 mm3). MR findings were compared with histopathologic findings. T2-weighted images clearly depicted the normal esophageal wall as consisting of 8 layers. In 39 (95%) of 41 carcinomas, the depth of mural invasion determined by MR imaging correlated well with that determined with histopathologic examination. The MR-based stage was higher in 2 (5%) cases than the histopathologic stage. High-resolution MR imaging at 1.5T shows a high diagnostic accuracy for evaluating the mural invasion of superficial esophageal carcinoma, thus potentially enabling preoperative histopathologic staging.

Adult↗
PubMed2001

Cloning and characterization of a novel mouse immunoglobulin superfamily gene expressed in early spermatogenic cells.

We cloned and characterized a novel immunoglobulin superfamily gene from the cDNA library of adult mouse testis. This gene was expressed in the spermatogenic cells and hence termed SgIGSF. The predicted SgIGSF protein was composed of 445 amino-acid residues and contained a signal peptide, three extracellular immunoglobulin (Ig)-like domains, a transmembranous domain, and a cytoplasmic domain. SgIGSF mRNA consisted of two size species, 2.1- and 4.5-kb in length. Besides testis, SgIGSF mRNA was also expressed in a variety of organs, including the cerebrum, liver, kidney, and epididymis. The testis and liver expressed both the 2.1- and 4.5-kb transcripts, whereas the cerebrum and epididymis predominantly expressed the 4.5-kb one. In situ hybridization analysis in testis revealed that SgIGSF mRNA signal was localized to the spermatogenic cells from spermatogonia to zygotene spermatocytes. These results suggested that SgIGSF occurs in the plasma membrane of spermatogenic cells during the earlier stages of spermatogenesis.

Amino Acid Sequence↗
PubMed2001

Second allogeneic peripheral blood stem cell transplantation with fludarabine-based low-intensity conditioning regimen for relapsed myelodysplastic syndrome after allogeneic bone marrow transplantation.

We describe the case of a 51-year-old patient with relapsed myelodysplastic syndrome after allogeneic bone marrow transplantation (BMT), who underwent allogeneic peripheral blood stem cell transplantation (PBSCT) after conditioning with a novel regimen consisting of fludarabine, busulfan, and antithymocyte globulin. The second PBSCT was performed early, at 3 months after the initial allogeneic BMT, but it was well tolerated and complete hematologic remission was documented. The patient did not experience any early transplantation-related organ toxicity but died from opportunistic infection 6 months after the second transplantation. Our experience suggests that this novel regimen may induce remission and could be offered to patients relapsing after the first transplantation; however, the fludarabine-containing regimen might be accompanied by profound immunosuppression.

Antineoplastic Agents↗
PubMed2001

Acquired storage-pool disorders occurring late after allogeneic bone marrow transplantation: partial activation of platelets in asymptomatic patients.

Bone marrow transplantation (BMT) may be complicated by coagulation abnormalities. The present study evaluated whether platelets might be activated in patients who had undergone BMT without significant coagulopathy. The patients selected had received allogeneic BMTs a median of 39 months before the study (range, 11-124 months) and had not received cyclosporine, FK506 (tacrolimus), or other medication affecting cyclo-oxygenase for at least 3 months prior to the collection of blood samples. Furthermore, patients had platelet counts greater than 100 x 10(9) cells/L and normal serum creatinine levels. Twenty-five healthy volunteers acted as controls. Platelet aggregation studies and a mepacrine assay of platelets showed abnormal aggregation and decreased staining in some patients. The platelet storage-pool adenosine 5'-triphosphate (ATP) level in 15 patients after BMT was 0.45+/-0.24 micromol per 10(11) platelets, whereas the level in 18 controls was 1.03+/-0.36 micromol per 10(11) platelets (P = .00078). The total ATP levels of platelets in patients and controls were 4.33+/-1.14 and 5.63+/-1.51 micromol per 10(11) platelets, respectively (P = .016). With the exception of 1 patient, plasma levels of thrombomodulin and von Willebrand factor were all within the normal range. The average plasma level of 11-dehydrothromboxane B2 was significantly increased in 15 patients after BMT compared with controls, 20.6+/-8.2 and 10.3+/-1.2 pg/mL, respectively (P = .0004). These findings suggest a long-term process of platelet activation in patients after BMT and, following the cessation of cyclosporine, development of acquired storage-pool disorder of platelets.

Adenosine Triphosphate↗
PubMed2001

Hepatitis B virus reactivation in a patient with chronic GVHD after allogeneic peripheral blood stem cell transplantation.

We report a patient with fatal hepatitis B virus (HBV) reactivation after treatment for chronic graft-versus-host disease (GVHD) following allogeneic peripheral blood stem cell transplantation to treat chronic myelogenous leukemia. The presence of antibodies to hepatitis B surface antigen (HBsAb) prior to transplantation indicated previous HBV infection. Liver damage first developed 8 months after transplantation with the disappearance of HBsAb. Hepatitis B antigen was first noted during an examination of liver damage that occurred 22 months after transplantation. Retrospective examination of serum by real-time detection polymerase chain reaction (RTD-PCR) revealed HBV in both the first and second episodes of liver damage (89 copies/mL and 2 x 10(6) copies/mL, respectively). HBV may have been reactivated, leading to fatal liver damage in this HBsAb-positive patient. We propose that RTD-PCR-based analysis should be performed to diagnose liver dysfunction after hematopoietic stem cell transplantation.

Antibodies, Viral↗
PubMed2001

Effect of additional chromosomal abnormalities in acute promyelocytic leukemia treated with all-trans-retinoic acid: a report of 17 patients.

Seventeen cases of acute promyelocytic leukemia (APL) treated with all-trans-retinoic acid (ATRA) and combination chemotherapy at Tokyo Metropolitan Komagome Hospital between 1992 and 1999 were reviewed, and divided into 2 karyotype-based cytogenetic groups. One group comprised 7 patients with either the typical t(15;17) alone or a normal karyotype, and the other group comprised 10 patients with additional karyotypic abnormalities. No patient had received prior chemotherapy or irradiation, and no cases were complicated by a history of myelodysplastic syndrome before the diagnosis of APL. There were no significant differences in clinical characteristics at disease presentation. Complete remission was achieved in all 17 patients and karyotypes of bone marrow cells normalized in all cases. No differences were found in relapse rate, overall survival, or disease-free survival between the 2 groups. The analysis did not reveal any significant effect of additional chromosomal abnormalities on the prognosis of APL patients undergoing treatment with ATRA. However, a small number of patients were assessed in this study, and further cumulative studies are needed.

Adolescent↗
PubMed2001

Association of polymorphisms in the beta-2 and beta-3 adrenoceptor genes with risk of colorectal cancer in Japanese.

BACKGROUND: The adrenergic receptor system is involved in thermogenesis and in the activation of lipid mobilization in fat cells, and polymorphisms in the beta-2 and beta-3 adrenoceptor genes (BAR2 and BAR3) have been reported to be associated with obesity and insulin resistance. To examine links between polymorphisms in these genes and the risk of colorectal cancer in Japanese, we conducted the present hospital-based case-referent study. METHODS: Mutations of the BAR2 gene at codon 27 (Gln27Glu) and of the BAR3 gene at codon 64 (Trp64Arg) were examined in 131 patients with colorectal cancer (cases) and in 239 cancer-free referents. We also collected information on environmental factors, using a questionnaire approach. Odds ratios (ORs) were estimated with an unconditional logistic model, after adjustment for potential confounding factors. RESULTS: The proportional distribution of the mutations in BAR2 and BAR3 did not differ between cases and referents. Analysis of a subgroup with a higher body mass index showed that the Trp64Arg variant increased the OR (2.63; 95% confidence interval, 1.13-6.11) for colon cancer, but not for rectal cancer, compared with the Trp64 genotype. Altered ORs for colon and rectal cancers with the Gln27Glu variant were not observed in either the subgroup with the lower body mass index or the subgroup with the higher body mass index. CONCLUSION: These findings suggest that the BAR3 polymorphism may alter the susceptibility to colon cancer risk in obese subjects. To confirm this finding, a further study with a larger number of subjects is now required.

Adult↗
PubMed2001

Hepatocyte transplantation: clinical and experimental application.

Hepatocyte transplantation has been proposed as an alternative to whole-organ transplantation to support many forms of hepatic insufficiency. Based on a significant body of work, the technique of hepatocyte transplantation has recently moved into the clinic in order to reestablish liver function without organ transplantation or to bridge the time between whole-organ liver transplantation. In addition, hepatocyte transplantation has also been proposed as a liver-directed gene therapy for a number of inherited hepatic disorders by transplanting either freshly isolated hepatocytes or genetically altered hepatocytes. To establish a research system based on the developing technology of hepatocyte transplantation, chimeric small animal models using human hepatocytes have recently been established, which would allow the study of human hepatocyte-specific functions, such as hepatitis viral infection and replication in vivo. Various aspects related to the recent progress and existing obstacles in the area of hepatocyte transplantation are summarized in this report.

Animals↗
PubMed2001

Antibacterial action of tryptanthrin and kaempferol, isolated from the indigo plant (Polygonum tinctorium Lour.), against Helicobacter pylori-infected Mongolian gerbils.

We evaluated the effect of tryptanthrin and kaempferol, both isolated from Polygonum tinctorium Lour., against Helicobacter pylori colony formation in vitro and in H. pylori-infected Mongolian gerbils. H. pylori suspension was mixed with solution of tryptanthrin and/or kaempferol and placed onto agar plates. These plates were incubated at 37 degrees C, under 10% CO2 for 5 days, and the H. pylori colonies were counted. For the in vivo experiment, Mongolian gerbils were inoculated with H. pylori ATCC 43504 orally. After 4 weeks, the infected gerbils were given tryptanthrin and/or kaempferol, administered orally, twice a day for 10 days. The animals were killed and the number of live H. pylori in their stomachs was determined. In vitro both tryptanthrin and kaempferol significantly decreased the numbers of H. pylori colonies a dose-dependent manner. An additive effect on colony formation was observed with the combined use. In the in vivo experiment, oral administration of tryptanthrin and/or kaempferol significantly decreased the numbers of colonies in the gerbils' stomachs. We concluded that tryptanthrin and kaempferol were effective against H. pylori in vivo.

Animals↗