Biomedical subjects

K Ota

Publications and source records attributed to K Ota.

At least 73 records · Page 4Linked to original sources

PubMed1999

Establishment of persistent infection with HIV-1 abrogates the caspase-3-dependent apoptotic signaling pathway in U937 cells.

Treatment of 26L cells, a subclone obtained from U937 cells, with TNF-alpha or DNA-damaging agents such as teniposide (VM26) and camptothecin (CPT) induced morphologically and biochemically typical apoptotic changes, including the activation of procaspase-3. The cells persistently infected with HIV-1 (26L/HIV), however, showed a marked resistance to VM26 and CPT, whereas they hardly lost the sensitivity to TNF-alpha. TNF-alpha-induced apoptosis of 26L/HIV cells proceeded without the increase in caspase-3 activity, indicating that signaling for apoptosis in the infected cells proceeded through an alternative caspase-3-independent pathway which could respond to TNF-alpha but not to VM26 and CPT. The evidence that p-toluenesulfonyl-l-lysine chloromethyl ketone (a trypsin-like serine protease inhibitor) blocked VM26- and CPT-induced apoptotic changes but not TNF-alpha-induced apoptosis also supported the existence of the alternative TNF-alpha-inducible pathway. The results also suggest that a TLCK-sensitive protease is involved upstream of the procaspase-3 activation process and that the protease is essential for the progress of VM26- and CPT-induced apoptosis. The similar effect of HIV-1-productive infection on the apoptosis induced by the DNA-damaging agents was also confirmed by utilizing U1 cells, which are latently HIV-1-infected U937 cells. The cells became resistant to these agents after induction of the viral production by pretreatment with PMA. These results suggest that persistent HIV-1 infection blocks an apoptotic pathway triggered by DNA damaging agents through the inhibition of the procaspase-3 activation process.

Apoptosis↗

PubMed1999

Combination of transileocolic vein obliteration and balloon-occluded retrograde transvenous obliteration is effective for ruptured duodenal varices.

Duodenal varices are a rare site of hemorrhage in patients with portal hypertension, but their rupture is a serious and often fatal event. We report a 65-year-old woman who presented with hematemesis and melena. She was admitted to our department because of prolonged shock, despite having received transfusion of a large volume of blood. Upper gastrointestinal endoscopy revealed nodular varices with active bleeding in the second portion of the duodenum. Endoscopic injection sclerotherapy (EIS) was performed using a tissue adhesive agent, alpha-cyanoacrylate monomer, with only temporary benefit. However, anemia continued to progress after the procedure. Therefore, we combined transileocolic vein obliteration (TIO) with balloon-occluded retrograde transvenous obliteration (B-RIO), using 5% ethanolamine oleate with iopamidol to obliterate the varices. Complete hemostasis was achieved without complications. Neither recurrence of varices nor further bleeding has occurred for over 3 years. We conclude that combined TIO and B-RTO, which can obstruct both the feeding and the draining vessels of duodenal varices to retain the sclerosing agent completely in the varices, is a safe and effective hemostatic measure for ruptured duodenal varices, when EIS has failed to accomplish complete hemostasis.

Aged↗

PubMed1999

The AATPAP sequence is a very efficient signal for O-glycosylation in CHO cells.

The peptide signal sequence for protein O-glycosylation is not fully characterized, although a recent in vitro study proposed that the sequence motif, XTPXP, serves as a signal for mucin-type O-glycosylation. Here, we show that the AATPAP sequence acts as an efficient O-glycosylation signal, in vivo. A secreted fibroblast growth factor (secFGF) was used as a model to analyze glycosylation and its effects on the biological activity of FGF. Two constructs encoding [AATPAP]secFGF in which AATPAP was introduced at the N- or C-terminus of secFGF were constructed in an eukaryotic expression vector. [AATPAP]secFGF proteins were then expressed in Chinese hamster ovary (CHO) cells and secreted into the surrounding medium, primarily as modified forms sensitive to sialidase but not to peptide N-glycosidase F. The modifying groups were not seen when the AATPAP sequence was converted to AAAPAP or when [AATPAP]secFGF was expressed in mutant cells incapable of UDP-GalNAc biosynthesis. The results indicate that the modifying groups were mucin-type O-glycans and that the AATPAP served as an efficient O-glycosylation signal sequence. The O-glycosylated forms of [AATPAP]secFGF were as mitogenic toward human vascular endothelial cells as unmodified secFGF, suggesting that introduction of the signal into biologically active polypeptides is a promising approach with which O-glycosylation may be achieved without affecting original activity.

Amino Acid Sequence↗

PubMed1999

Nursing students' response to a case study in ethics.

This paper describes the responses of undergraduate nursing students to an ethical clinical case study. Students in a baccalaureate program were given a case study before a lecture on ethical principles and the same case study after this lecture. These responses raise questions about the content of nursing ethics classes in Japan. The place of individual patient rights and the role of the family in a situation of non-disclosure about diagnosis and prognosis were major issues for the students. The responses reveal the problem of the 'nurse-in-the-middle' between the patient and others whose values differ. Students' post-lecture responses emphasized communication among the people involved.

Adult↗

PubMed1999

[Parvovirus B19 infection-induced anemia and leukocytopenia after myomectomy].

A 38-year woman was hospitalized because of myoma uteri. She underwent myomectomy on September 30, 1997 with 2,000 ml blood loss. No blood transfusion was required, but she received a plasma protein product. On the 14th postoperative day, a complete blood count revealed anemia (Hb 9.3 g/dl) and leukocytopenia (1,600/ul). But it did not reveal anemia before the operation. Bone marrow smears showed erythroblastopenia with giant proerythroblasts. Anti-parvovirus B19 IgM antibody were positive in the serum and parvovirus B19 DNA was detected in the bone marrow cells by polymerase chain reaction. From the results, the patient was diagnosed as the anemia and leukocytopenia secondary to parvovirus B19 infection. Parvovirus B19 was not detected in the samples of the plasma protein product received on the myomectomy. The reticulocyte gradually decreased to 1/1000 on the 20th postoperative day. The anemia and leukocytopenia gradually improved. This case shows that parvovirus B19 infection could cause hematological disorders in the normal person under acute blood loss. This report warns that a careful observation is necessary for the patients who have received operations with acute blood loss.

Adult↗

PubMed1999

Role of membrane-type matrix metalloproteinase 1 (MT-1-MMP), MMP-2, and its inhibitor in nephrogenesis.

Extracellular matrix (ECM) proteins, their integrin receptors, and matrix metalloproteinases (MMPs), the ECM-degrading enzymes, are believed to be involved in various biological processes, including embryogenesis. In the present study, we investigated the role of membrane type MMP, MT-1-MMP, an activator pro-MMP-2, in metanephric development. Also, its relationship with MMP-2 and its inhibitor, TIMP-2, was studied. Since mRNAs of MT-1-MMP and MMP-2 are respectively expressed in the ureteric bud epithelia and mesenchyme, they are ideally suited for juxtacrine/paracrine interactions during renal development. Northern blot analyses revealed a single approximately 4.5-kb mRNA transcript of MT-1-MMP, and its expression was developmentally regulated. Inclusion of MT-1-MMP antisense oligodeoxynucleotide (ODN) in the culture media induced dysmorphogenetic changes in the embryonic metanephros. MMP-2 antisense ODN also induced similar changes, but they were relatively less; on the other hand TIMP-2 antisense ODN induced a mild increase in the size of explants. Concomitant exposure of MT-1-MMP and MMP-2 antisense ODNs induced profound alterations in the metanephroi. Treatment of TIMP-2 antisense ODN to metanephroi exposed to MT-1-MMP/MMP-2 antisense notably restored the morphology of the explants. Specificity of the MT-1-MMP antisense ODN was reflected in the selective decrease in its mRNA and protein expression. The MT-1-MMP antisense ODN also resulted in a failure in the activation of pro-MMP-2 to MMP-2. These findings suggest that the trimacromolecular complex of MT-1-MMP:MMP-2:TIMP-2 modulates the organogenesis of the metanephros, conceivably by mediating paracrine/juxtacrine epithelial:mesenchymal interactions.

Aging↗

PubMed1999

High-resolution ultrastructural comparison of renal glomerular and tubular basement membranes.

BACKGROUND/AIMS: Glomerular basement membranes (GBM) and tubular basement membranes (TBM) consist of a fine meshwork composed mainly of type IV collagen. Each segment of tubules has specialized physiologic functions, and thus we investigated the ultrastructure of various basement membranes in rat kidneys. METHODS: Since purifying basement membranes from different tubule segments is technically challenging, we employed tissue negative staining rather than conventional negative staining to compare the ultrastructures of proximal and distal TBM and GBM in normal rats. We also assessed the distribution of extracellular matrix components including type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin in the basement membranes by immunohistochemistry. RESULTS: TBM and GBM of normal rats showed a fine meshwork structure consisting of fibrils forming small round to oval pores. Short- and long-pore diameters in proximal tubules were 3.3 +/- 0.5 and 3.9 +/- 0.6 nm, respectively, and in distal tubules 3.5 +/- 0.7 and 4.3 +/- 0.8 nm, respectively. For GBM the respective diameters were 2.5 +/- 0.5 and 3.0 +/- 0.5 nm. Immunohistochemical analysis showed no significant difference in distribution of extracellular matrix components between proximal and distal TBM. However, immunofluorescence scores of alpha1 chain of type IV collagen, fibronectin, and laminin were higher in the TBM than in the GBM. On the other hand, heparan sulfate proteoglycan was higher in the GBM. CONCLUSION: Ultrastructural differences in renal basement membranes may be related to differences in physiologic function in each segment.

Animals↗

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

Characterization of fibroblast growth factor-6 expressed by Chinese hamster ovary cells as a glycosylated mitogen for human vascular endothelial cells.

The gene for fibroblast growth factor (FGF)-6/hst-2 was originally identified by its close homology with the FGF-4/hst-1 gene. Aside from its ability to transform cultured fibroblasts, the characteristics of FGF-6 protein have only been studied using a simple preparation from E. coli. In the present study, we expressed FGF-6 cDNA in CHO cells and characterized the resultant protein. We found that CHO cells secreted several forms of the FGF-6 polypeptide, and that there were multiple N-terminal modifications. The longest form (18-kDa) contained the sequence, SerProAlaGlyAlaArg, as its N-terminus, which was consistent with the signal peptide cleavage site predicted from its primary structure. The core polypeptide was primarily modified by heterogeneous N-glycans that were sialylated to a small degree; among them, biantennary structures were found to predominate. Moreover, possible O-glycosylation was also detected. N-glycosylated FGF-6 potently induced DNA synthesis and proliferation of human vascular endothelial cells, whereas in the absence of N-glycosylation, FGF-6 mitogenicity was substantially diminished. The results clearly indicate that FGF-6 expressed by mammalian cells is a glycosylated mitogen for vascular endothelial cells and further suggests that N-glycosylation plays a key role in determining the mitogenicity of FGF-6.

Animals↗

PubMed1999

Phylogenic analysis of echovirus type 30 isolated from a large epidemic of aseptic meningitis in Japan during 1997-1998.

During 1997 to 1998, a nationwide epidemic of aseptic meningitis occurred in Japan. More than 4,500 isolates from patients with aseptic meningitis were identified as echovirus type 30. To investigate the character of these isolates, we examined the nucleotide sequences of thirty-seven geographical representatives and compared them with 50 strains isolated during the past 20 years. The phylogenic analysis used partial sequences from either the VP1 or VP4-VP2 region of the viral capsid. This analysis revealed that the isolates were divided into six genomic groups. All isolates identified during 1997-1998 belonged to only two genomic groups; these two groups are thought to be the causative viral agents involved in the recent epidemic.

Enterovirus B, Human↗

PubMed1999

Fas-mediated cytotoxicity by gammadelta T cells during acute rejection in xenotransplantation of spheroidal aggregate-cultured hepatocytes.

Xenogeneic transplantation has recently become a subject of interest for the transplantation community due to the current organ shortage, which could be partially or even totally solved by the development of this strategy. However, xenogenetic rejection remains a formidable barrier preventing such use in a clinical setting. The spheroidal aggregate-cultured hepatocytes of WKA rats were injected into the spleen of C3H mice, and quantitative assessment of transplanted xenogeneic hepatocytes using 99mTc-GSA demonstrated that hepatocytes decreased dramatically 2 days after transplantation (day 2) and few viable hepatocytes in spheroids were detected on day 3. The NK activity significantly increased on day 1, and gammadelta receptor/FasL-expressing T cells appeared on day 2. These results suggested that xenogeneic cytotoxicity consisted of gammadelta T cells through the Fas/Fas ligand system, as well as non-T-cell-mediated cellular response, in the MHC-unrestricted pathway in this intrasplenically transplanted xenogeneic hepatocyte model.

Animals↗

PubMed1998

Complex effects of general anesthesia on sensory processing in the spinal dorsal horn.

A chronic animal preparation allowed us to compare activity of the same single, spinal dorsal horn neurons in the physiologically intact, awake, drug-free state and in the anesthetized state. The inhalation anesthetic enflurane produced profound, and at times, opposite effects on spinal dorsal horn neuron responses to non-noxious and noxious receptive field stimulation. Some effects would not have been predicted, based upon current understanding of anesthetics.

Analysis of Variance↗

PubMed1998

Association between polymorphisms in the type 1 sigma receptor gene and schizophrenia.

Several antipsychotic agents such as haloperidol and rimcazole are known to bind to sigma receptors with high affinity, and evidence for a potential link between sigma receptors and the etiology of schizophrenia has been reported. The present study was conducted to systematically search for nucleotide variants of the type 1 sigma receptor gene in 48 schizophrenics. Two polymorphisms were found: GC-241-240TT in the 5' flanking region and Gln2Pro. These two polymorphisms were in nearly complete linkage disequilibrium with each other. The Pro2 variant of the Gln2Pro polymorphism changes the endoplasmic reticulum retention signal motif. These polymorphisms were examined in an extended sample of schizophrenics (n = 308) and controls (n = 433) and a significant association between the presence of the TT/Pro2 haplotype and schizophrenia was observed (odds ratio = 1.27, P = 0.04).

Adolescent↗

PubMed1998

Assessment of topogenic functions of anticipated transmembrane segments of human band 3.

Band 3 protein is a typical multispanning membrane protein whose membrane topology has been extensively studied from various protein chemical approaches. To clarify the membrane topogenesis of this multispanning protein on the endoplasmic reticulum, the topogenic functions of the anticipated transmembrane segments were individually assessed in an in vitro system using two series of model proteins in which each segment was placed in either a "stop-transfer" context or a "translocation initiation" context. They were expressed in a cell-free system containing rough microsomal membranes, and their topologies were evaluated by taking advantage of either sensitivity to protease or accessibility to N-glycosylation. We found that some segments seem to possess insufficient topogenic functions for membrane integration: the second transmembrane segment (TM2) is insufficient for the stop-transfer sequence, and TM3, TM5, and TM7 are not sufficient for the translocation initiation. In contrast to these phenomena, we herein demonstrate that TM2 shows an efficient stop-transfer function when it is near the preceding TM1 and suggest that TM3, TM5, and TM7 are followed by TM segments with a strong topogenic function to form Nexo/Ccyt topology, via which the preceding segments are integrated into the membrane. From these results, we propose that the interactions between the TMs should be operative during membrane integration, and that the segments with a weak topogenic function are given a transmembrane orientation by their following TMs.

Amino Acid Sequence↗

PubMed1998

Analysis of the TPA regulatory element in the genomic poly(ADP-ribose) synthetase gene in human leukemia U937 cells.

The human leukemia U937 cells differentiate into monocyte/macrophage-like cells when treated with 12-O-tetradecanoylphorbol-13-acetate (TPA). We observed that during this process, both protein and mRNA levels for PARS markedly decreased in U937 cells. Through deletion analysis of the PARS regulatory gene, we found that the sequence within the first intron region was responsible for the TPA-dependent repression. Electrophoretic mobility shift assays (EMSAs) and Southwestern blot analysis indicate that this element bound specifically to a nuclear protein. TPA treatment abolished the binding of the protein in U937 cells but not in HeLa cells. DNase I footprinting data show that the cis regulatory element is located between residues 328 and 383. We further examined the function of this cis element (BS207) in a basal promoter regulatory reporter construct and found that this cis element (BS207) functions as an enhancer via the binding of an unknown trans-acting factor. TPA treatment diminished the binding activity of the factor in U937 cells, resulting in a decrease in the enhanced activity to the basal level. These results suggest that abolishment of the binding of a special nuclear protein to the first intron of the PARS gene is related to the TPA-responsive downregulation of PARS in U937 cells.

Base Sequence↗

PubMed1998

Evidence supporting an association between the DRB1 gene and schizophrenia in Japanese.

The authors attempted a replication of earlier studies that detected an association of HLA-DR4 and DR1 with schizophrenia. Japanese patients with schizophrenia (n = 266, DSM-III-R criteria) and Japanese controls (n = 283) were genotyped for DR1 and DR4 alleles using a combination of group-specific polymerase chain reaction (PCR) amplification and PCR-restriction fragment length polymorphism. Significant positive association with HLA-DR1 [odds ratio (OR) = 1.87, corrected p = 0.04] and a negative association with HLA-DR4 (OR = 0.63, corrected p = 0.02) was noted. DR1 and DR4 were independently associated with schizophrenia. The association of the DR1-positive/DR4-negative genotype with schizophrenia was modest (OR = 2.60, 95% confidence intervals = 1.38-4.89, corrected p = 0.008). Thus, these findings support an association of the HLA DRB1 gene locus with schizophrenia in the Japanese population. Since both DR4 and DR1 are positively associated with rheumatoid arthritis, our findings are not simply consistent with the known negative association between schizophrenia and rheumatoid arthritis.

Female↗

PubMed1998

Transactivation of transforming growth factor alpha gene by hepatitis B virus preS1.

Hepatitis B virus (HBV) causes acute and chronic liver injury, and integration of HBV DNA is considered to be an important pathogenic determinant for hepatocarcinogenesis and tumor development. Transforming growth factor alpha (TGF-alpha) drastically accelerates hepatocarcinogenesis when it is overexpressed in TGF-alpha transgenic mice (C. Jhappan et al., Cell, 61: 1137-1146, 1990). In HBV-infected patients, hepatocellular carcinoma (HCC) cells show elevated expression of TGF-alpha (C. C. Hsia et al., J. Med. Virol., 43: 216-221, 1994), the mechanism for which, however, has not been clarified yet. We here show that preS1, a part of the HBV large surface protein, carries a transcriptional transactivation domain and activates the transcription of the TGF-alpha gene by 2-fold in human HCC HuH6 cells. The responsive elements are restricted to the 315-bp segment of the proximal TGF-alpha promoter (-373 to -59). Furthermore, the expression of TGF-alpha was markedly increased in permanently preS1-producing HuH6 transformants. The crucial role for HBV preS1 in hepatocarcinogenesis and tumor development through transactivation of the TGF-alpha gene may give us new insight into the understanding of pathogenesis and therapy of viral hepatocarcinogenesis.

Animals↗

PubMed1998

Aluminum decreases the magnesium concentration of spinal cord and trabecular bone in rats fed a low calcium, high aluminum diet.

Current epidemiological surveys in the Western Pacific (Guam, and Kii Peninsula and West New Guinea) have suggested that low calcium (Ca), magnesium (Mg) and high aluminum (Al) and manganese (Mn) in river, soil and drinking water may be implicated in the pathogenetic process of foci of amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD). The condition of unbalanced minerals was experimentally mimicked in this study using rats. Male Wistar rats, weighing 200 g, were maintained for 60 days on the following diets: (A) standard diet, (B) low Ca diet, (C) low Ca diet plus high Al. Magnesium concentrations were determined in spinal cord and trabecular bone using inductively coupled plasma emission spectrometry (ICP). In the experimental group maintained on a low Ca, high Al diet, magnesium concentration of the spinal cord was lower than the group fed a standard diet. Also, magnesium concentration of lumbar vertebra showed lower values in the experimental group fed a low Ca, high Al diet than did those on a standard diet or low Ca diet without supplemental aluminum. Our data indicate that low Ca, high Al diet influences Mg concentration in bone and central nervous system (CNS) tissues and that a low Ca, high Al diet diminishes Mg in bone and CNS tissues, thereby inducing loss of calcification in bone and degeneration of CNS tissue due to alteration of the normal biological effects of Mg.

Aluminum↗