Biomedical subjects

H Koike

Publications and source records attributed to H Koike.

At least 73 records · Page 4Linked to original sources

PubMed2000

Cloning of rat nephrin: expression in developing glomeruli and in proteinuric states.

BACKGROUND: Nephrin is identified as a product of the gene mutated in a patient with congenital nephrotic syndrome of the Finnish type. However, its precise localization and function are not yet fully clarified. METHODS: To clone the rat homologue of nephrin, polymerase chain reaction (PCR) was employed. To elucidate the localization and expression of nephrin, immunohistological analysis with a specific antirat nephrin antibody, reverse transcription-PCR, and RNase protection assay were performed. RESULTS: Amino acid sequences of rat and human nephrin are highly homologous (82.2% identity). The domain structure of nephrin is also highly conserved between rats and humans. The rat nephrin was detected only in kidney glomeruli along glomerular capillary walls, and its localization was always identical to that of the anti-slit diaphragm monoclonal antibody (mAb) 5-1-6-recognized antigen in normal matured and fetal rat glomeruli and in the glomeruli of proteinuric states. The nephrin staining pattern was clearly distinguished from that of zonula occludens-1 (ZO-1), alpha3-integrin, or podocalyxin. mRNA expression for nephrin was first detected in the fetal rat kidneys at 18.5 embryonic days. Nephrin mRNA expression decreased just after injection of mAb 5-1-6 (47.4%) or puromycin aminonucleoside (51.2%), and the staining pattern of nephrin shifted from a linear to a granular pattern in both proteinuric states. CONCLUSIONS: Nephrin is localized in slit diaphragm in the matured glomeruli and is identical with mAb 5-1-6 antigen. Nephrin is involved in the development of proteinuria not only in mAb 5-1-6 nephropathy, but also in puromycin aminonucleoside nephropathy.

Amino Acid Sequence↗

PubMed2000

Effects of high-temperature treatments on a thermophilic cyanobacterium Synechococcus vulcanus.

Effects of high-temperature treatments on a thermophilic cyanobacterium, Synechococcus vulcanus, were studied, and the following results were obtained. (1) Oxygen evolution and the PSII photochemical reaction were the most sensitive sites and started to be inactivated at temperatures slightly higher than the cultivating temperature. (2) The decrease in the fluorescence Fv value reflected the inactivation of the charge separation reaction of PSII as well as that of the oxygen evolution reaction. (3) The dark fluorescence level, Fo, showed an increase at around 70 degrees C, which was partially reversed by further incubation at 50 degrees C. This increase reflected the inactivation of PSII reaction centers and probably dissociation of phycobilisomes from the PSII reaction center complexes. (4) At higher temperatures, phycobiliproteins disassembled and denatured in a pH-dependent manner, causing a large Fo decrease. (5) Cell membranes became leaky to low-molecular-weight substances at around 72 degrees C. (6) Inhibition of growth of the cells was recognized when the cells were pretreated at temperatures higher than 72 degrees C. Reversibility of the high-temperature effects and relationship between viability of the cells and the degradation of the cell membranes are discussed.

Bacterial Proteins↗

PubMed2000

Reduced platelet serotonin content in rabbits with dietary hypercholesterolemia.

Serotonin [5-hydroxytryptamine (5-HT)] has been implicated in platelet activation and vasoconstriction, two processes that contribute to arterial thrombosis in atherosclerotic diseases. In the present study, Japanese White rabbits fed 1% cholesterol for 5 weeks were used to investigate the response of hypercholesterolemic vascular arteries and platelets to 5-HT. Contractions of the thoracic aorta induced by 5-HT were comparable between the cholesterol-fed group and the age-matched control group. However, acetylcholine-induced vasodilation in arteries preconstricted with 5-HT was moderately but significantly attenuated in the cholesterol-fed rabbits. Platelet aggregation responses to 5-HT (0.1-3 micromol/l) in combination with epinephrine (5 micromol/l), adenosine diphosphate (ADP) (0.3-10 micromol/l), 9,11-dideoxy-9alpha,11alpha-methanoepoxy-prostaglandin F2alpha (U-46619) (1-30 micromol/l) or collagen (3 microg/ml) were significantly enhanced in cholesterol-fed rabbits. In contrast, platelet 5-HT content determined with a high-performance liquid chromatography-electrochemical detector (HPLC-ECD) was significantly decreased in cholesterol-fed rabbits. These results suggest a possible association among the endothelial dysfunction, platelet aggregation and platelet 5-HT content in rabbits with dietary hypercholesterolemia.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2000

[Putaminal signal hypointensity on T2 weighted MR image in a patient with corticobasal degeneration].

In the course of a 74-year-old woman with corticobasal degeneration (CBD), bilateral putaminal signal hypointensity appeared on T2 weighted MR image. This right-handed woman noticed progressive difficulty in writing and using chopsticks during two years. Neurological examination in February 1998 showed apraxia, rigidity, akinesia and myoclonus, which were more marked in the right hand side. MRI revealed atrophy of the left frontotemporal lobes. These findings were compatible to CBD. Her symptoms progressed slowly. On re-admission due to aspiration pneumonia in December 1998, she showed difficulty in swallowing and walking in addition to the signs and symptoms described above. MRI revealed bilateral putaminal signal hypointensity on T2 weighted image. In the literature, totally 9 cases in 2 reports showed similar putaminal signal hypointensity. Although this finding is unusual in CBD, advanced degenerative process in the putamen might have induced this change due possibly to the accumulation of iron secondary to the nerve cell loss.

Aged↗

PubMed2000

[A case of testicular tumor in a patient with Down's syndrome: a case report].

A 40-year-old man with Down's syndrome was admitted to our hospital for complaint of painless, swollen right scrotum. Computed tomography revealed a right testicular tumor and mass of iliac fossa. Right high orchiectomy and extirpation of mass were performed. Histological diagnosis of right testicular tumor was seminoma and the mass was an external iliac lymph node metastasis of seminoma. After operation, radiation therapy was performed.

Adult↗

PubMed1999

Membrane-anchored metalloprotease MDC9 has an alpha-secretase activity responsible for processing the amyloid precursor protein.

MDC9, also known as meltrin gamma, is a membrane-anchored metalloprotease. MDC9 contains several distinct protein domains: a signal sequence followed by a prodomain and a domain showing sequence similarity to snake venom metalloproteases, a disintegrin-like domain, a cysteine-rich region, an epidermal-growth-factor-like repeat, a transmembrane domain and a cytoplasmic domain. Here we demonstrate that MDC9 expressed in COS cells is cleaved between the prodomain and the metalloprotease domain. Further, when MDC9 was co-expressed in COS cells with amyloid precursor protein (APP695) and treated with phorbol ester, APP695 was digested exclusively at the alpha-secretory site in MDC9-expressing cells. When an artificial alpha-secretory site mutant was also co-expressed with MDC9 and treated with phorbol ester, APP secreted by alpha-secretase was not increased in conditional medium. Inhibition of MDC9 by a hydroxamate-based metalloprotease inhibitor, SI-27, enhanced beta-secretase cleavage. These results suggest that MDC9 has an alpha-secretase-like activity and is activated by phorbol ester.

ADAM Proteins↗

PubMed1999

Tissue-inherent fate of GPI revealed by GPI-anchored GFP transgenesis.

To clarify the fate of glycosylphosphatidylinositol (GPI) in mammals, we developed GPI-anchored enhanced green fluorescent protein (EGFP-GPI) and transgenic mice carrying this fusion construct. When it was introduced to culture cells, the EGFP-GPI protein was correctly sorted to plasma membranes and microsomes depending on GPI biosynthesis. Transgenic mice carrying EGFP-GPI were found to show a broad transgene expression. Histologically, a prominent polarized localization of EGFP-GPI protein was observed in various epithelia, the nervous system and liver and secreted from some exocrine glands, as well as non-polarized presence in non-epithelial tissues, demonstrating a tissue-inherent manner of GPI sorting.

Acrosin↗

PubMed1999

Overexpression of myotonic dystrophy protein kinase in C2C12 myogenic culture involved in the expression of ferritin heavy chain and interleukin-1alpha mRNAs.

The specific function of myotonic dystrophy protein kinase (DMPK) is still not known. We found that overexpression of human DMPK in C2C12 myogenic culture induces the expression of ferritin heavy chain (FN-H) mRNA using differential display analysis. The quantity of FN-H mRNA was greater in the DMPK transfectant with five CTG triplet repeats in the 3'-untranslated region, while it was lower in the transfectant with 46 CTG repeats, over that of the control clone. We also investigated the quantity of interleukin 1-alpha (IL-1alpha) mRNA in each culture, due to the fact that this cytokine is able to induce FN-H expression, regardless of the concentration of free iron. Quantitative, competitive polymerase chain reaction (PCR) analysis revealed that the quantity of IL1-alpha mRNA is higher in the transfectant with five repeats, compared to the quantity of mRNA in the control clone; however, it is markedly lower in the clone with 46 repeats. These results suggest that overexpression of DMPK in C2C12 cultures may up-regulate IL-1alpha expression, resulting in the induction of FN-H expression. However, a large number of CTG repeats in the 3'-untranslated region of the DMPK gene may affect the pathway of IL-1alpha transcription, thereby resulting in decreased expression of FN-H.

Animals↗

PubMed1999

Association and dissociation of the calcium-binding domains of calpain by Ca2+.

The calmodulin-like domain of calpain is important for the association of the calpain large and small subunits. We expressed the calmodulin-like domains of the large subunits of rabbit mu- and m-calpains and their small subunits in E. coli and purified them to homogeneity. Unlike the full-length subunits, the calmodulin-like domains are soluble in buffer containing Ca2+. We performed gel filtration chromatography of the purified proteins and found that all three calmodulin-like domains exist as homodimers in the absence of Ca2+ and dissociate into monomers upon the addition of Ca2+.

Animals↗

PubMed1999

Protective effects of sialyl Lewis X and anti-P-selectin antibody against lipopolysaccharide-induced acute lung injury in rabbits.

The prophylactic effects of selectin inhibitors on lipopolysaccharide-induced acute lung injury were studied in rabbits by using sialyl Lewis X-oligosaccharide and PB1.3, an anti-human P-selectin monoclonal antibody. Lipopolysaccharide-induced acute lung injury resembles that of the acute respiratory distress syndrome, in which there is a decrease in arterial blood oxygen tension (PaO2) and an increase in the difference between alveolar and arterial oxygen tension (A-aDO2). Prophylactic treatment with the selectin inhibitors, sialyl Lewis X-oligosaccharide (55 mg kg(-1) i.v. bolus injection immediately before lipopolysaccharide administration + 36 mg kg(-1) h(-1) i.v. infusion for 4 h) and PB1.3 (5 mg kg(-1) i.v. bolus injection immediately before lipopolysaccharide administration), prevented the lipopolysaccharide-induced impairments in pulmonary gas exchange. In contrast, these agents had no significant effects on lipopolysaccharide-induced systemic hypotension, the decrease in the number of circulating white blood cells and platelets, the decline in blood pH, or the increase in arterial CO2 tension (PaCO2). These results indicate that selectin inhibitors including sialyl Lewis X-oligosaccharide and the anti-P-selectin antibody, PB1.3, attenuate lipopolysaccharide-induced acute lung injury in rabbits. This is the first demonstration that P-selectin is directly involved in the development of lipopolysaccharide-induced impairments in pulmonary gas exchange.

Animals↗

PubMed1999

Increased expression of cyclooxygenases and peroxisome proliferator-activated receptor-gamma in Alzheimer's disease brains.

Recent studies suggest that inflammatory events are associated with plaque formation in the brains of patients with Alzheimer's disease (AD). Treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) of these patients appears to slow the progression of disease. We assessed the occurrence of cyclooxygenases (COX-1 and -2) and peroxisome proliferator-activated receptor-gamma (PPARgamma) in temporal cortex from normal and AD brains using specific antibodies. In AD brains, protein levels of COX-1 were increased in both cytosolic and particulate fractions, and COX-2 protein was also increased in the particulate fraction. On the other hand, PPARgamma level was increased in the cytosolic fraction but not in the particulate fraction. Thus, expression levels of COX-1, COX-2, and PPARgamma may change in AD brains. In addition, several NSAIDs which are also PPARgamma activators, such as indomethacin, inhibited COX-2 expression in glial cells. These results suggest that PPARgamma activators have inhibitory effects on inflammatory events in AD brains.

Aged↗

PubMed1999

Fluctuations of hepatitis C virus load are not related to amino acid substitutions in hypervariable region 1 and interferon sensitivity determining region.

Hepatitis C virus (HCV) load is one of the most important predictive factors of response to interferon treatment. However, little is known about the mode and determinants of viremia. The mode of viremia was investigated in 78 patients with chronic HCV genotype 1b infection during 1-2 years follow up. Virus load, determined by a branched chain DNA amplification assay, was stable in 73 of 78 (93.6%) patients, whereas 5 (6.4%) showed marked fluctuation (from undetectable level to more than 10 Meq/ml) in viral titer. To study the mechanisms mediating fluctuations in viral titer, amino acid sequences of two regions were examined; hypervariable region (HVR) 1 and the interferon sensitivity determining region (ISDR). Multiple amino acid substitutions were observed in HVR 1 but no relationship was evident between substitutions and virus titers. In contrast, no amino acid substitutions were observed in the ISDR in any patients with stable virus titer during a follow-up period of 12-24 months (7-24 samples) or in one patient who was observed for 15 years. Interestingly, multiple amino acid substitutions in the ISDR appeared in only two of the five patients with marked titer fluctuation, when the virus decreased markedly. Alanine aminotransferase levels in these five patients correlated with viral load. The data suggest that amino acid substitutions in HVR1 and ISDR are not essential for changes in viral titer. Possible mechanisms of fluctuations of viral titer and amino acid substitutions in the ISDR accompanying marked reductions in viral load are discussed.

Alanine Transaminase↗

PubMed1999

Predictive value of different hepatitis C serological assays in the treatment of chronic hepatitis C with interferon alpha.

In order to predict the complete response rate of natural interferon-alpha (nIFN-alpha) treatment in patients with chronic active hepatitis C, we examined the predictive value (PV) of different hepatitis C serological assays. We performed first generation (ver.1) and second generation (ver.2) hepatitis C virus (HCV) branched DNA-probe assays (bDNA-probe), HCV core protein assay (core protein), HCV Amplicor Monitor assay (amplicor monitor), and HCV competitive polymerase chain reaction (competitive PCR) assay, using serum samples collected immediately before initiation of treatment. For each marker, we studied, in patients stratified by serological group (Gr), which predictive value (PV) of the HCV titers showed association with the therapeutic effect. In 59 Gr 1 patients, complete response to nIFN-alpha treatment was predicted from the following PVs for each marker: 0.5 Meq/ml or less (odds ratio 11.7: P = 0.0010) with ver.1, 1.0 Meq/ml or less (odds ratio 5.3; P = 0.0119) with ver.2 of the bDNA-probe, 50 pg/ml or less (odds ratio 10.3; P = 0.0062) with core protein, 200 x 10(3) copy/ml or less (odds ratio 7.8; P = 0.0031) with amplicor monitor, and 10(4) copy/ml or less (odds ratio 6.2; p = 0.8395) with competitive PCR. In 27 Gr 2 patients, the PV for each marker indicating complete response was as follows: There was no relationship between PV and therapeutic effect with ver.1 of the bDNA-probe, while the PVs for the other markers were 0.2 Meq/ml or less (odds ratio 2.2; P = 0.3788) with ver.2, 20 pg/ml or less (odds ratio 5.6; P = 0.0597) with core protein, 400 x 10(3) copy/ml or less (odds ratio 4.0; P = 0.2965) with amplicor monitor, and 10(5.5) copy/ml or less (odds ratio 29.2; P = 0.0096) with competitive PCR. Our findings showed that complete response to the treatment may be predicted using the appropriate PV for each marker.

Adult↗

PubMed1999

Enzyme-linked immunosorbent assay to detect hepatitis C virus serological groups 1 to 6.

By conventional serological grouping methods, it is possible to determine hepatitis C virus (HCV) serological groups for genotypes 1a, and 1b, and genotypes 2a, and 2b, but not for other genotypes, i.e., 3a, 3b, 4a, 5a, and 6a. In this study, we attempted to serologically group HCV with the Murex HCV serotyping 1 to 6 assay (Murex Diagnostics, Kent, UK), using an enzyme-linked immunosorbent assay (ELISA) based on genotype-specific peptides from the NS4 region. The subjects of this study were 365 patients infected with HCV of genotype 1a, 1b, 2a, 2b, 3a, or 3b. The sensitivity of the assay was 100% in patients with genotype 1a, 82.7% in those with 1b, 68.5% in those with 2a, 84.2% in those with 2b, 50.0% in those with 3a, and 76.5% in those with genotype 3b. The overall sensitivity was 78.4%. The specificity of the assay was 100% in the subjects with genotype 1a, 98.8% in those with 1b, 98.4% in those with 2a, 96.9% in those with 2b, 100% in those with 3a, and 100% in those with genotype 3b. The overall specificity was 98.6%. The concordance of the assay was 100% in subjects with genotype la, 81.7% in those with 1b, 67.4% in those with 2a, 81.6% in those with 2b, 50.0% in those with 3a, and 76.5% in those with genotype 3b. The overall concordance was 77.5%. We believe it would be better to serotype with the Murex HCV serotyping 1 to 6 assay, if other than serological group (Gr) 1 or Gr 2 is suspected in particular ethnic groups or in subjects with an indeterminate result with the Immucheck HCV Gr assay (Kokusai, Kobe, Japan), assuming that the genotype must be other than 1a, 1b, 2a, or 2b.

Enzyme-Linked Immunosorbent Assay↗

PubMed1999

Increased severity of viral myocarditis in mice lacking lymphocyte maturation.

The role of lymphocytes in the pathogenesis of viral myocarditis is controversial. To better understand how lymphocyte maturation controls a virus-induced myocarditic process, a murine model of viral myocarditis was utilized. Encephalomyocarditis virus (EMCV) was inoculated intraperitoneally into three kinds of mice; virus-susceptible C57BL/6, virus-resistant 129/SV and recombination activity gene (RAG)-2 knockout 129/SV mice. The RAG2 participate in the maturity of T and B lymphocytes. Survival rate, heart weight (HW), HW to body weight (BW) ratio, viral genome, cardiac inflammation and myocardial necrosis were evaluated after EMCV (500 plaque forming unit/mouse) inoculation. On post-inoculation day 10, the survival rate of C57BL/6, 129/SV and RAG2 knockout mice were 42, 90 and 0%, respectively. Myocardial viral titer was significantly (P<0.05) higher in C57BL/6 and RAG2 knockout mice than in 129/SV mice. In situ hybridization demonstrated the EMCV genome in the myocardium of RAG2 knockout and C57BL/6 mice, but not in 129/SV mice. At day 8, HW and HW/BW ratios were elevated (P<0.05) in RAG2 knockout mice as well as C57BL/6 mice compared with 129/SV mice. Myocardial necroses were more severe in RAG2 knockout mice than in wild-type 129/SV mice. In conclusion, matured lymphocytes protect the development of viral myocarditis which includes viral replication and myocardial apoptosis.

Animals↗

PubMed1999

Prevalence of TT virus before and after blood transfusion in patients with chronic liver disease treated surgically for hepatocellular carcinoma.

BACKGROUND: To examine the prevalence of TT virus (TTV) before and after blood transfusion, we retrospectively examined serum samples obtained from 55 patients who received blood transfusions before, during and after resection of hepatocellular carcinoma. METHODS: TT virus DNA was extracted from serum samples and detected by nested polymerase chain reaction. Before transfusion, seven (12.7%) were positive for TTV. Patients were transfused whole blood or separated blood components (fresh frozen plasma, platelet and/or red blood cells), the total amount of transfused fresh frozen plasma ranging from 12 to 271 (median 38) units. RESULTS: Seven (14.6%) of the 48 TTV-negative patients became positive for TTV-DNA 1 month after transfusion. Only one of the seven patients, who was already positive for HCV-RNA, exhibited elevation of alanine aminotransferase. Five of the newly infected seven patients become negative for TTV during a 2 year follow up. CONCLUSIONS: Our findings suggest that the proportion of patients with TTV was relatively high in this sample, and that the prevalence of TTV transmission by blood components was also relatively high (14.6%). Although TTV persisted for more than 6 months in some patients, infection was not noticeable during the course of chronic liver disease.

Carcinoma, Hepatocellular↗

PubMed1999

Granular cell tumour of the ulnar nerve.

Although granular cell tumours have been demonstrated to have a neural origin, they rarely arise in peripheral nerve trunks. We report a case of granular cell tumour of the ulnar nerve in a 51-year-old man. Though dissectable from the nerve, this intraneural tumour showed microscopic involvement of focal nerve fibres. This tumour tended to infiltrate the nerve in the same manner as a neurofibroma.

Granular Cell Tumor↗

PubMed1999

Thimet oligopeptidase cleaves the full-length Alzheimer amyloid precursor protein at a beta-secretase cleavage site in COS cells.

We developed an assay method using a novel quenched fluorescent substrate (QFS) flanking the beta-cleavage site of amyloid precursor protein (APP), and purified a candidate beta-secretase from bovine brain. N-terminal amino acid analysis showed the candidate to be thimet oligopeptidase (TOP). The cDNA for human TOP was cloned from a human brain cDNA library and expressed in COS cells. The enzyme was further purified on a Ni2+-agarose column. TOP cleaved the Swedish Alzheimer's substrate (SEVNLDAEFR) as well as the normal substrate (SEVKMDAEFR). We then coexpressed TOP with APP695 in COS cells, collected transfected cells and conditioned media, and analyzed them by immunoblotting. The antibody against the specific secreted APP cleaved by beta-secretase (sAPPbeta) detected the secretion of sAPPbeta only from APP/hTOP-overexpressing cells, and not from cells overexpressing of antisense hTOP cDNA. Finally, we analyzed the immunolocalization of overexpressed hTOP in COS cells. Most hTOP was localized in the nuclei, but a small amount was localized in the Golgi or other organelles around the nuclei. These results suggest that TOP has a beta-secretase-like activity responsible for the processing of APP.

Amino Acid Sequence↗