Biomedical subjects

H Hotta

Publications and source records attributed to H Hotta.

At least 37 records · Page 2Linked to original sources

PubMed2000

Requirement of activation of the extracellular signal-regulated kinase cascade in myocardial cell hypertrophy.

The signal transduction mechanisms mediating hypertrophic responses in myocardial cells (MCs) remain uncertain. We investigated the role of the extracellular signal-regulated kinase (ERK) cascade in myocardial cell hypertrophy by the strategy of using the adenovirus-mediated overexpression of mitogen-activated protein kinase (MAPK)/ERK kinase (MEK), which is the upstream activator of ERK. We generated recombinant adenoviruses expressing constitutively active MEK1 (MEK1 EE) and dominant negative MEK1 (MEK1 DN). Overexpression of MEK1 EE in MCs activated ERK1/2 and subsequently induced atrial natriuretic peptide (ANP) mRNA expression. In addition, MEK1 EE overexpression resulted in an increase in cell size and sarcomeric reorganization. In contrast, overexpression of MEK1 DN in MCs inhibited endothelin-1 (ET-1)-, phenylephrine (PE)-, leukemia inhibitory factor (LIF)-, isoproterenol (ISP)-, and mechanical stretch-induced ERK activation and ANP mRNA expression. MEK1 DN overexpression inhibited ET-1-, PE-, LIF-, and ISP-induced increases in cell size and sarcomeric reorganization. Consistent with the observed effects on cellular morphology, overexpression of MEK1 EE resulted in an increase in amino acid incorporation, while overexpression of MEK1 DN inhibited ET-1-, PE-, LIF-, ISP-, and mechanical stretch-induced increases in amino acid incorporation. These results indicate that the ERK cascade plays an important role in the signaling pathway leading to the development of myocardial cell hypertrophy.

Adenoviridae↗

PubMed2000

Structure and serologic properties of O-specific polysaccharide from Citrobacter freundii possessing cross-reactivity with Escherichia coli O157:H7.

Citrobacter freundii OCU158 is a serologically cross-reactive strain with Escherichia coli O157:H7. To explore the close relationship between two strains, we have analyzed the chemical structures of O-specific polysaccharides and antigenic properties of lipopolysaccharides (LPSs) of both strains. The structure of O-specific polysaccharides from both strains was found to be identical by chemical and nuclear magnetic resonance analyses, in which D-PerNAc was 4-acetamido-4,6-dideoxy-D-mannose: [-->4)-beta-D-Glc-(1-->3)-alpha-D-PerNAc-(1-->4)-alpha-D-GalNAc-(1 --> 3)-alpha-L-Fuc-(1-->](n). The enzyme immunoassay using LPS derived either from E. coli O157 or from C. freundii could equally detect high levels of serum antibodies against LPS in patients with enterohemorrhagic E. coli (EHEC) O157 infection. Absorption of antibodies in EHEC patient serum by LPS from E. coli O157 or C. freundii, however, showed a difference in the epitopes. This difference was attributable to the epitope specificity of the core region and/or lipid A structure in LPS.

Antibodies, Bacterial↗

PubMed2000

Prevalence of GB virus C/Hepatitis G virus infection among various populations in Surabaya, Indonesia, and identification of novel groups of sequence variants.

A molecular epidemiological study was performed to investigate the prevalence of GB virus C/hepatitis G virus (GBV-C/HGV) infection among various populations in Surabaya, Indonesia. The prevalence of GBV-C/HGV RNA, determined by reverse transcription-PCR for a portion of the NS3 region of the viral genome, was 2.7% (4 of 150) among randomly collected blood donor sera, which were all negative for both hepatitis B virus surface antigen and antibodies against hepatitis C virus (HCV). On the other hand, the prevalence among anti-HCV-positive blood donors was 17.8% (13 of 73), with the ratio being significantly higher than that observed with the anti-HCV-negative blood donors (P < 0.001). A high prevalence of GBV-C/HGV infection was also observed among patients with chronic liver disease, such as chronic hepatitis (5.7%), liver cirrhosis (11. 5%), and hepatocellular carcinoma (7.0%), and patients on maintenance hemodialysis (29.0%). No correlation was observed between GBV-C/HGV viremia and serum alanine aminotransferase levels in the populations tested, suggesting the possibility that GBV-C/HGV does not cause apparent liver injury. Phylogenetic analysis of sequences of a portion of the 5' untranslated region and the E1 region of the viral genome identified, in addition to a previously reported then novel group of GBV-C/HGV variants (group 4), another novel group of variants (group 5). This result suggests that GBV-C/HGV can be classified into at least five genetic groups. GBV-C/HGV isolates of group 4 and group 5 were each shown to comprise approximately 40% of the total Indonesian isolates.

5' Untranslated Regions↗

PubMed2000

Lysophosphatidylcholine inhibits endothelial cell migration and proliferation via inhibition of the extracellular signal-regulated kinase pathway.

Lysophosphatidylcholine (lysoPC), a major lipid component of oxidized low density lipoprotein, inhibits endothelial cell (EC) migration and proliferation, which are critical processes during angiogenesis and the repair of injured vessels. However, the mechanism(s) of lysoPC-induced inhibition of EC migration and proliferation has not been clarified. In this report, we demonstrate the critical role of extracellular signal-regulated kinase (ERK) in growth factor-stimulated EC migration and proliferation as well as their inhibition by lysoPC. EC migration and proliferation stimulated by basic fibroblast growth factor (FGF-2) were blocked by inhibition of ERK activity by both the specific mitogen-activated protein kinase kinase (MEK) 1 inhibitor PD98059 and the overexpression of a dominant-negative mutant of MEK1. Conversely, overexpression of a constitutively active mutant of MEK1 increased EC migration and proliferation, which were comparable to those of ECs stimulated with FGF-2. LysoPC inhibited FGF-2-induced ERK activation via prevention of Ras activation without inhibiting tyrosine phosphorylation of phospholipase C-gamma. Taken together, our data demonstrate that ERK activity is required for FGF-2-induced EC migration and proliferation and suggest that inhibition of the Ras/ERK pathway by lysoPC contributes to the reduced EC migration and proliferation.

Animals↗

PubMed2000

Effects of nicotine on blood flow and delayed neuronal death following intermittent transient ischemia in rat hippocampus.

A cholinergic neural vasodilative response in the cerebral cortex and hippocampus, independent of metabolic vasodilation, was recently demonstrated by activating the nicotinic acetylcholine receptors (nAChRs) via activation of cholinergic neurons originating in the nucleus basalis of Meynert and septal complex in the basal forebrain and projecting to the cortex and hippocampus (see reviews by Sato A and Sato Y: Neurosci Res 14: 242--274, 1992; Sato A and Sato Y: Alzheimer Dis Assoc Disord 9: 28--38, 1995). In the present study, we aimed to examine whether an increase in regional blood flow in the hippocampus (Hpc-BF) following stimulation of the nAChRs by i.v. injection of nicotine could improve the delayed death of the hippocampal neurons following transient ischemia in rats. Hpc-BF was measured by using a laser Doppler flowmeter. During intermittent (every 2 min) transient occlusion for a total of 6 min of bilateral carotid arteries besides permanent ligation of bilateral vertebral arteries, Hpc-BF decreased to about 16% of the preocclusion level, and 5 or 7 d later, after the occlusion, delayed neuronal death occurred in approximately 70% of the CA1 hippocampal neurons. Hpc-BF was increased dose-dependently by injection of nicotine (30--100 microg/kg, i.v.), independent of mean arterial pressure. Nicotine (30--100 microg/kg) administered 5 min before occlusion slightly but significantly attenuated the occlusion-induced decrease in Hpc-BF. The delayed death of the CA1 hippocampal neurons occurring after transient occlusion was attenuated by pretreatment with nicotine (30--100 microg/kg) to approximately 50% of the total neurons. The results indicate that nAChR stimulation-induced increases in Hpc-BF can protect against ischemia-induced delayed death of hippocampal neurons.

Animals↗

PubMed2000

Viral load in Indonesian patients with chronic liver disease and in blood donors infected with different subtypes of hepatitis C virus.

The viral load of different hepatitis C virus (HCV) subtypes, including the globally distributed HCV-1b and the unique Indonesian subtype HCV-1c, was analyzed using serum samples obtained from Indonesian blood donors and patients with chronic liver disease. The mean viral load of HCV-1c was comparable with that of HCV-1b, suggesting that HCV-1c is as pathogenic as HCV-1b. On the other hand, the mean viral load of HCV-2a was lower than that of HCV-1b or HCV-1c, with this result being consistent with previous observations. Interestingly, some HCV-2a strains were associated with a high viral load that was almost equivalent to that of HCV-1b and HCV-1c. This result implies the possibility that there exists a minor fraction of HCV-2a strains that cause higher levels of viremia compared with the majority of ordinary HCV-2a strains.

Adult↗

PubMed1999

High-resolution structure of the conger eel galectin, congerin I, in lactose-liganded and ligand-free forms: emergence of a new structure class by accelerated evolution.

BACKGROUND: Congerin I is a member of the galectin (animal beta-galactoside-binding lectin) family and is found in the skin mucus of conger eel. The galectin family proteins perform a variety of biological activities. Because of its histological localization and activity against marine bacteria and starfish embryos, congerin I is thought to take part in the eels' biological defense system against parasites. RESULTS: The crystal structure of congerin I has been determined in both lactose-liganded and ligand-free forms to 1. 5 A and 1.6 A resolution, respectively. The protein is a homodimer of 15 kDa subunits. Congerin I has a beta-sheet topology that is markedly different from those of known relatives. One of the beta-strands is exchanged between two identical subunits. This strand swap might increase the dimer stability. Of the known galectin complexes, congerin I forms the most extensive interaction with lactose molecules. Most of these interactions are substituted by similar interactions with water molecules, including a pi-electron hydrogen bond, in the ligand-free form. This observation indicates an increased affinity of congerin I for the ligand. CONCLUSIONS: The genes for congerin I and an isoform, congerin II, are known to have evolved under positive selection pressure. The strand swap and the modification in the carbohydrate-binding site might enhance the cross-linking activity, and should be the most apparent consequence of positive selection. The protein has been adapted to functioning in skin mucus that is in direct contact with surrounding environments by an enhancement in cross-linking activity. The structure of congerin I demonstrates the emergence of a new structure class by accelerated evolution under selection pressure.

Amino Acid Sequence↗

PubMed1999

The effects of morphine on supraspinal and propriospinal somatocardiac reflexes in anesthetized rats.

In anesthetized rats, the effects of i.v. injection of morphine on supraspinally- and spinally-mediated tachycardiac reflex responses of heart rate (HR) and cardiac sympathetic nerve reflex activity were examined following electrical stimulation of either a non-segmental hindlimb (tibial) or a segmental (3rd or 4th intercostal, IC3-4) afferent nerve. In central nervous system (CNS)-intact rats, the supraspinally-mediated reflex increase in HR in response to tibial afferent nerve stimulation was augmented by morphine, whereas the increase in response to IC3-4 afferent nerve stimulation was variable. Both the supraspinally-mediated myelinated (A) and unmyelinated (C) reflex discharges in the cardiac sympathetic nerve elicited by tibial afferent nerve stimulation were augmented by morphine. The effects of morphine on A- and C-sympathetic reflex discharges elicited by IC3-4 afferent nerve stimulation varied depending upon whether the discharge was of supraspinal or spinal origin. In spinal rats (spinalized at the cervical level), tibial afferent nerve stimulation did not produce any HR response, whereas IC3-4 afferent nerve stimulation produced a reflex increase in both HR and sympathetic reflex discharges of spinal origin. Furthermore, these spinal HR and sympathetic nerve reflex responses were inhibited by morphine. In conclusion, morphine depressed somatocardiac sympathetic reflexes at the spinal level, but enhanced these reflexes at the supraspinal level, leading to different effects of morphine on somatically-induced HR responses of supraspinal and spinal origins depending upon the segmental levels of afferent nerves stimulated.

Afferent Pathways↗

PubMed1999

Detection of various epitopes of murine osteopontin by monoclonal antibodies.

We immunized rats with recombinant murine osteopontin protein and obtained four monoclonal antibodies recognizing distinct epitopes of murine osteopontin. OPN1.2 recognized the amino-terminal half of OPN, while OPN2.2, OPN2.3, and OPN3.1 recognized the carboxy-terminal half of OPN. The epitope recognized by OPN2.2 was destroyed by further cleavage of the carboxy half of OPN. The epitope recognized by OPN2.3 was located in the amino-terminal end of the carboxy half of OPN, whereas that recognized by OPN3.1 was located in the carboxy-terminal end of the carboxy half of OPN. OPN1.2 and OPN2.2 recognized thrombin-cleaved osteopontin, whereas thrombin-cleaved osteopontin was not recognized by OPN2.3 and OPN3.1. Thus, these monoclonal antibodies will be useful in structure/function studies of the role of osteopontin in murine models of disease.

Animals↗

PubMed1999

Uterine contractility and blood flow are reflexively regulated by cutaneous afferent stimulation in anesthetized rats.

The effects of cutaneous mechanical afferent stimulation of various skin areas on uterine contractility and blood flow were examined in anesthetized non-pregnant rats. The contractility of the uterus was measured by the balloon method in the uterus. The uterine blood flow was measured by laser Doppler flowmetry. Noxious pinching stimulation of the perineum for 1 min induced an abrupt contraction of the uterus during stimulation. Pinching of a hindpaw or perineum and innocuous brushing of the perineum for 1 min increased uterine blood flow. Stimulation of other skin areas produced no changes in uterine contractility or blood flow. Most uterine responses were abolished by severance of the pelvic nerves, which innervated the uterus. The activity of pelvic parasympathetic efferent nerves to the uterus increased following perineal pinching. All these cutaneous stimulation-induced responses of uterine contractility, blood flow and pelvic efferent nerve activity still existed, and were even augmented, after acute spinalization. These results indicate that cutaneous mechanical sensory stimulation can regulate uterine contractility and blood flow by a segmental spinal reflex mechanism via uterine parasympathetic efferent nerves.

Anesthesia↗

PubMed1999

CD44 variants but not CD44s cooperate with beta1-containing integrins to permit cells to bind to osteopontin independently of arginine-glycine-aspartic acid, thereby stimulating cell motility and chemotaxis.

The expression of osteopontin (OPN), CD44 variants, and integrins has been correlated with tumorigenesis and metastasis. Here we show that these proteins cooperate to enhance cell motility. First, we demonstrate that several different CD44 variants bind to OPN in an arginine-glycineaspartic acid-independent manner, but that the standard form of CD44 does not. These CD44 variants bind to both the amino- and COOH-terminal portions of OPN independently of the arginine-glycine-aspartic acid sequence, suggesting that multiple domains on OPN can be bound by the CD44 variants. Antibodies directed against the integrin beta1 subunit are able to inhibit this binding. The binding of CD44 variants to OPN is significantly augmented by both anti-CD44s and anti-CD44v antibodies. This augmentation by anti-CD44 antibodies is OPN specific and, again, can be blocked by anti-beta1 antibodies. Finally, we show that OPN binding by CD44 variants/beta1-containing integrins promotes cell spreading, motility, and chemotactic behavior.

Animals↗

PubMed1999

Hepatitis delta virus genotype IIb predominates in an endemic area, Okinawa, Japan.

Hepatitis delta virus (HDV) infection is relatively common in the Miyako Islands, Okinawa, Japan, where the infection has been reported to be associated with low pathogenicity. HDV RNA extracted from each of 6 patients with HDV-related chronic liver disease living in the islands was amplified by reverse transcription-polymerase chain reaction and examined genetically to determine the HDV genotype. All isolates from the 6 patients were classified as genotype II by the neighbor-joining method. However, these isolates had relatively low homology (75-81%) to the HDV genotype II isolate reported from Japan, and showed relatively high identity (83-95%) to the novel genotype II isolate (HDV genotype IIb) recently reported from Taiwan. Phylogenetic analysis showed that the 6 isolates form a novel group within HDV genotype II. Furthermore, there was notable variation in sequence among the 6 isolates compared with the relatively close clustering of HDV isolates within limited areas (e.g., United States, Archangelos, Turkey, Albania, Peru). HDV genotype II in the Miyako Islands is therefore unique, and HDV infection may have been introduced at a relatively early time in this area.

Adult↗

PubMed1999

Levels of chondroitin sulfate isomers in synovial fluid of patients with hip osteoarthritis.

We determined the levels of chondroitin sulfate (CS) isomers in the synovial fluid of patients with hip osteoarthritis (OA) to investigate their significance as markers reflecting extracellular matrix metabolism in joint tissues. A cross-sectional study of synovial fluid aspirated from 50 hip joints of 50 patients with OA was performed. Concentrations of chondroitin-4-sulfate (C4S) and chondroitin-6-sulfate (C6S) were determined by high-performance liquid chromatography. Levels of each marker molecule were investigated in relation to age and radiological stage of the disease. In all disease stages, the dominant CS isomer in synovial fluid was C6S. There was a significant negative correlation between levels of C6S and age. A significant inverse correlation was also observed between the ratio of C6S to C4S and age. Results of analysis of covariance in which age was covariate showed that the ratio of C6S to C4S in advanced and terminal stage OA was lower than that in early stage OA. The present results indicate that the ratio of CS isomers in synovial fluid in hip OA varies with the severity of disease. These molecules in synovial fluid may serve as a useful marker reflecting extracellular matrix metabolism in OA.

Adult↗

PubMed1999

Biofilm in complicated urinary tract infection.

We studied the clinical efficacy of oral treatment with ciprofloxacin (CPFX) alone and combined with clarithromycin (CAM) in patients with complicated urinary tract infection with or without an indwelling catheter. Patients were randomly allocated to 600 mg CPFX (CPFX group) or to 600 mg CPFX plus 600 mg CAM (combination group) for 14 days. Evaluation was done on day 14 according to the criteria advocated by the Japanese Urinary Tract Infection Committee. In patients with a urinary catheter, the combination achieved a higher complete bacterial elimination rate (50.0%) and clinical efficacy rate (83.9%) than CPFX alone (30.0 and 61.5%, respectively). While no significant difference was found in the bacterial elimination rate between the two groups, the clinical efficacy of the combination (40.0%) was superior to that of CPFX alone (23.3%) in patients with an indwelling catheter. The better clinical efficacy of the combination may partly be attributed to the antibiofilm effect of CAM in the clinical setting. The results also indicate that difficulties still remain in the treatment of complicated urinary tract infections in patients with an indwelling catheter.

Adult↗

PubMed1999

Contingent negative variation in children with anorexia nervosa.

BACKGROUND: Central catecholamines, particularly dopaminergic and noradrenergic systems, have affected the appetitive behavior in patients with anorexia nervosa (AN). The purpose of this study is to distinguish the characteristics of contingent negative variation (CNV) and postimperative negative variation (PINV), which may reflect the level of catecholamine in children with AN. METHODS: Eight children with AN aged 10 to 15 years and 23 age-matched healthy children were recruited. Contingent negative variation was recorded from the frontal midline (Fz), central midline (Cz) and parietal midline (Pz) referenced to linked earlobes during 30 trials consisting of a warning stimulus and an imperative stimulus with an interstimulus interval of 2 s and an intertrial interval of 10 s. The imperative stimulus of each trial required a button press. RESULTS: Children with AN had a diminished amplitude of the CNV. They had a significantly more attenuated early CNV and late CNV amplitude at Cz than normal children. No significant differences were observed between AN children and normal children in the amplitude of PINV at all three electrode sites. No difference could be found between the two groups in the frequencies of normal and abnormal duration of PINV. CONCLUSION: These findings suggest that early CNV may be diminished by norepinephrine deficiency and late CNV may be attenuated by dopaminergic deficiency in children with AN. Reduced CNV may represent impaired cognitive processes which reflect impaired appetitive behavior in AN children.

Adolescent↗

PubMed1999

The NS5A protein of hepatitis C virus partially inhibits the antiviral activity of interferon.

The non-structural protein 5A (NS5A) of some hepatitis C virus (HCV) isolates has been implicated in the inhibition of the antiviral activity of interferon (IFN). In the present study, the possible inhibitory effects of NS5A from two isolates of HCV subtype 1b, HCV-1bJk and M094AJk, and their chimeric form on the antiviral activity of IFN were examined. HCV-1bJk and M094AJk are categorized as IFN resistant and IFN sensitive, respectively, based on the sequences of the IFN-sensitivity determining region (ISDR). When encephalomyocarditis virus was used as a challenge virus, NS5A was shown to eliminate the antiviral activity of IFN, with inhibition being more prominent with HCV-1bJk NS5A than with M094AJk NS5A. Moreover, the inhibition was significantly weaker in cells expressing a chimeric NS5A that had a short stretch of 49 amino acids (aa 2209-2257), including the ISDR sequence, from M094AJk in the backbone of the HCV-1bJk sequence than in cells expressing the original NS5A from HCV-1bJk. These results suggest an important role for the 49 aa sequence, including the ISDR, in the inhibition of IFN-mediated antiviral activity. On the other hand, only a slight reduction of IFN antiviral activity by HCV-1bJk NS5A was observed when vesicular stomatitis virus was used as a challenge virus, and barely any reduction was observed when Japanese encephalitis virus was used. These results may reflect differential importance of each of the IFN-mediated signalling pathways in conferring resistance against different viruses.

3T3 Cells↗

PubMed1999

Seroprevalence and subtype distribution of hepatitis C virus among blood donors and intravenous drug users in northern/northeastern Thailand.

The prevalence of antibodies against hepatitis C virus (HCV) and the distribution pattern of HCV subtypes were analyzed among healthy blood donors and intravenous drug users (IVDUs) in northern/northeastern Thailand. The prevalence of anti-HCV antibodies was 3.2% (26/820) among blood donors in Khon Kaen, while it was 90% (71/79) among IVDUs in Chiang Rai. HCV RNA was detected in all anti-HCV-positive sera collected from blood donors and IVDUs tested, as determined by reverse transcription-PCR analysis. Sequence analyses of amplified fragments of the HCV genome revealed that in Khon Kaen and Chiang Rai, Thailand, HCV-3a (50-60%) was the most common HCV subtype, followed by HCV-1a, HCV-1b, and subtypes of clade 6, each at 10-20%.

Adolescent↗

PubMed1998

Complex formation of the nonstructural protein 3 of hepatitis C virus with the p53 tumor suppressor.

By co-immunoprecipitation analysis, we demonstrated that wt-p53 formed a complex with non-structural protein (NS) 3 of hepatitis C virus, both in the absence and the presence of NS4A, a viral cofactor that strongly associates with NS3. Deletional analysis revealed that a portion near the N-terminus of NS3 (amino acids (aa) 1055 and 1200), which is different from the NS4A binding site, was necessary for the complex formation with wt-p53. On the other hand, a portion near the C-terminus of wt-p53 (aa 301-360), which has been reported to contain the oligomerization domain, was important for the complex formation with NS3.

Base Sequence↗