Biomedical subjects

S Yokota

Publications and source records attributed to S Yokota.

At least 73 records · Page 4Linked to original sources

PubMed2000

Rapid morphological oscillation of mitochondrion-rich cell in estuarine mudskipper following salinity changes.

Morphological changes in the chloride cells or mitochondrion-rich (MR) cells in the skin under the pectoral fin of the estuarine mudskipper (Periophthalmus modestus) were examined in relation to intertidal salinity oscillation in river mouth. MR cells were distinguished between those in contact with the water (cells labeled with both mitochondrial probe DASPEI and Concanavalin-A, an apical surface marker of MR cells) and those that are not (DASPEI-positive only). After transfer of the fish from seawater to freshwater, no difference in the total MR cell density was observed, but the subpopulation of MR cells that are Concanavalin-A-positive decreased dramatically within 30 min. After 6 hr in freshwater, the fish were returned to seawater; the number of Con-A-positive MR cells increased to the initial levels rapidly. Thus, in seawater, mudskippers seem to open the apical crypts of the MR cells to secrete salt; in freshwater, they close the crypt of the MR cells tentatively, and tolerate hypotonicity until the rising tide. This unique response of chloride cells may also be seen in gills of other estuarine species.

Adaptation, Physiological↗

PubMed2000

Comparison of serum antibody titers to Helicobacter pylori lipopolysaccharides, CagA, VacA and partially purified cellular extracts in a Japanese population.

We examined the levels of antibody titers against Helicobacter pylori antigens, three types of lipopolysaccharides (LPSs), recombinant CagA antigen, recombinant VacA antigen and partially purified cellular antigens in the sera of Japanese volunteers. The three types of LPSs are LPS carrying the highly antigenic epitope, LPS carrying the weakly antigenic epitope and rough LPS, classified on the basis of antigenicity in humans. IgG titers against all H. pylori antigens tested were significantly different between gastroduodenal patients and healthy adults without H. pylori infection. IgG titers against LPS carrying the weakly antigenic epitope, rough LPS and VacA antigen, as well as IgA titers against the partially purified cellular extract were significantly higher in gastroduodenal patients than in H. pylori-positive healthy adults. However, IgG titers against LPS carrying the highly antigenic epitope, CagA antigen or the partially purified cellular extract showed no significant difference between patients and H. pylori-positive healthy adults. The results indicated that increases in IgG titers against VacA antigen and the weakly antigenic and core epitopes of LPS, and in IgA titer against the partially purified cellular extract, were associated with disease state and may be useful in identifying active infection of H. pylori.

Adult↗

PubMed2000

Topographical organization of projections from the subiculum to the hypothalamus in the rat.

The projections from the subiculum to the hypothalamus were comprehensively examined in the rat by using the anterograde Phaseolus vulgaris leucoagglutinin (PHA-L) and retrograde cholera toxin B subunit (CTb) methods. Tracing of efferents with PHA-L indicated that the medial preoptic region received projection fibers from the temporal two-thirds of the subiculum, whereas the anterior, tuberal, and mammillary regions received those from the full longitudinal extent of the subiculum. The subicular projections to the anterior and tuberal hypothalamic regions were also found to be organized in a topographical manner such that the temporal-to-septal axis of origin in the subiculum determined a ventromedial-to-dorsolateral axis of termination in the medial zone of the hypothalamus: Massive labeled fibers from the temporalmost part of the subiculum terminated in the subparaventricular zone and its caudal continuum around the dorsal and medial aspects of the ventromedial nucleus, and those from progressively more septal parts terminated in progressively more dorsolateral parts of the medial zone. In addition, the temporal-to-septal axis of origin in the subiculum tended to determine a medial-to-lateral axis of termination in the preoptic region as well as a ventral-to-dorsal axis of termination in the mammillary region. Furthermore, the temporal-to-septal axis of origin in the septal two-thirds of the subiculum corresponded to a ventrolateral-to-dorsomedial axis of termination in the medial mammillary nucleus. The topographical projections from the subiculum to the medial zone of the hypothalamus were confirmed by CTb experiments, representatively in the subicular projections to the anterior hypothalamic region. These results suggest that different populations of neurons existing along the longitudinal axis of the subiculum may exert their influences on the execution of different hypothalamic functions.

Animals↗

PubMed2000

Monosynaptic and disynaptic projections from the substantia nigra pars reticulata to the parafascicular thalamic nucleus in the rat.

We examined a direct pathway and an indirect pathway via the reticular thalamic nucleus (RT) from the substantia nigra pars reticulata (SNr) to the parafascicular thalamic nucleus (PF) by using anterograde and retrograde tract tracing methods. After biotinylated dextranamine (BDA) injection into the dorsolateral part of the SNr, many labeled fibers and axon terminals were distributed in the ventral part of the RT, as well as in the ventrolateral part of the PF, bilaterally with an ipsilateral dominance. After BDA injection into the ventral part of the RT, a plexus of labeled axons was found bilaterally with an ipsilateral dominance in the ventrolateral part of the PF. After combined injections of BDA into the dorsolateral part of the SNr and cholera toxin B subunit (CTb) into the ventrolateral part of the PF on the same side, overlapping distribution of BDA-labeled fibers and CTb-labeled neurons was observed in the ventral part of the RT ipsilateral to the injection sites, where the BDA-labeled axon terminals made symmetrical synaptic contacts with soma and dendrites of the CTb-labeled neurons.

Animals↗

PubMed2000

Enzyme cytochemical localization of sarcosine oxidase activity in the liver and kidney of several mammals.

We investigated the enzyme cytochemical localization of sarcosine oxidase (SOX) in the liver and kidney of several mammals using a cerium technique. First we measured the enzyme activities in the liver and kidney of several mammals and in several organs of mice. The highest activity was found in the Chinese hamster, followed by the mouse. Therefore, we used hamster and mouse tissues for enzyme cytochemistry. The liver and kidneys were fixed by perfusion with various concentrations of glutaraldehyde for 10 min. Tissue slices were incubated in reaction medium consisting of 50 mM TRIS-maleate buffer (pH 7.8), 9 mM sodium azide, 9.8 mM sarcosine, 25 microM FAD, 2 mM cerium chloride, 0.002% saponin, and 0.003% Triton X-100 for 0.5-8 h at 37 degrees C. Optimum staining reaction was obtained in tissues fixed with 0.2% glutaraldehyde, followed by incubation for 2-4 h. Electron-dense reaction products were present exclusively in peroxisomes. Within the peroxisomes strong reactions were observed in the matrix subjacent to the limiting membrane decreasing toward the center. The staining reaction was completely inhibited by 2 mM N-bromosuccinimide. These results indicated that SOX is a peroxisomal enzyme and that the enzyme might be associated with the peroxisomal membrane.

Animals↗

PubMed2000

Aggregate formation and degradation of overexpressed wild-type and mutant urate oxidase proteins. Quality control of organelle-destined proteins by the endoplasmic reticulum.

To analyze the cellular response caused by the overexpression of proteins in subcellular compartments, we constructed four expression clones encoding wild-type peroxisomal urate oxidase (UO), truncated UO lacking the peroxisomal targeting signal (UOdC), and chimeric UOs with a mitochondrial targeting signal (MTS) at the N-terminus of UOdC (MUOdC) or UO (MUO). After transfection, we examined COS-1 and HEK293 cells by immunofluorescence and immunoelectron microscopy, transmission electron microscopy, and pulse-chase experiments. The overexpressed UO and UOdC formed large electron-dense aggregates with no limiting membrane in both the cytoplasm and the nucleus. The UO aggregates exhibited the crystalloid structure quite similar to that of rat liver peroxisomal cores, whereas the UOdC aggregates formed a loose mass consisting of small dense substructures. The overexpressed MUOdC and MUO, on the other hand, formed other types of aggregates which were distributed in the cytoplasm. They consisted of tubular and circular membrane structures, which were morphologically confirmed to be derived from the endoplasmic reticulum (ER). No immunolabeling signals for MUOdC and MUO were present free in the cytoplasm and most of them were associated with membrane structures, suggesting that overexpressed UO containing the MTS attached to the ER membranes soon after synthesis and segregated from the cytosolic compartment. All the UO aggregates were stained for ubiquitin antigen. Pulse-chase experiments in combination with proteasome inhibitors suggested that proteasomes did not contribute to the degradation of these products.

Animals↗

PubMed2000

Effects of peroxisome proliferator-activated receptor-alpha and -gamma agonist, JTT-501, on diabetic complications in Zucker diabetic fatty rats.

This study has investigated the effects of JTT-501, a peroxisome proliferator-activated receptor (PPAR)-alpha and PPAR-gamma agonist, on the pathogenesis of diabetic complications in the Zucker diabetic fatty (ZDF) rats, a model of type 2 diabetes. Comparison is made with troglitazone, a PPAR-gamma agonist. The ZDF rats exhibited hyperglycaemia and hyperlipidaemia, and developed diabetic complications such as cataract, nephropathy, and neuropathy. Treatment with JTT-501 from the prediabetic stage controlled glycaemia and lipidaemia, and prevented the development of diabetic complications. Troglitazone was less effective in controlling serum cholesterol and neuropathy. ZDF rats developed diabetic osteopenia with reduced bone turnover, and this was prevented by JTT-501 and troglitazone, possibly mediated by increased bone turnover and bone formation. Since JTT-501 controlled glycaemia and lipidaemia in ZDF rats and prevented several diabetic complications, it is suggested that treatment with JTT-501, which activates both PPAR-alpha and PPAR-gamma, could provide a valuable therapeutic approach against diabetic complications in type 2 diabetes.

Absorptiometry, Photon↗

PubMed2000

Immunological detection of alkaline-diaminobenzidine-negativeperoxisomes of the nematode Caenorhabditis elegans purification and unique pH optima of peroxisomal catalase.

We purified catalase-2 of the nematode Caenorhabditis elegans and identified peroxisomes in this organism. The peroxisomes of C. elegans were not detectable by cytochemical staining using 3, 3'-diaminobenzidine, a commonly used method depending on the peroxidase activity of peroxisomal catalase at pH 9 in which genuine peroxidases are inactive. The cDNA sequences of C. elegans predict two catalases very similar to each other throughout the molecule, except for the short C-terminal sequence; catalase-2 (500 residues long) carries a peroxisomal targeting signal 1-like sequence (Ser-His-Ile), whereas catalase-1 does not. The catalase purified to near homogeneity from the homogenate of C. elegans cells consisted of a subunit of 57 kDa and was specifically recognized by anti-(catalase-2) serum but not by anti-(catalase-1) serum. Subcellular fractionation and indirect immunoelectron microscopy of the nematode detected catalase-2 inside vesicles judged to be peroxisomes using morphological criteria. The purified enzyme (220 kDa) was tetrameric, similar to many catalases from various sources, but exhibited unique pH optima for catalase (pH 6) and peroxidase (pH 4) activities; the latter value is unusually low and explains why the peroxidase activity was undetectable using the standard alkaline diaminobenzidine-staining method. These results indicate that catalase-2 is peroxisomal and verify that it can be used as a marker enzyme for C. elegans peroxisomes.

3,3'-Diaminobenzidine↗

PubMed2000

Myotonic dystrophy associated with 47 XYY syndrome.

A case of myotonic dystrophy with 47 XYY presented with tall stature and mental retardation. The patient was a 37-year-old male. In addition to grip myotonia and percussion myotonia, severe weakness and atrophy were noted in the face and the neck muscles and in the distal muscles of the four limbs. He also had diabetes mellitus, cataracts and sexual behavior abnormalities. He was found to be 47 XYY from chromosomal examinations. The combination of 47 XYY syndrome and myotonic dystrophy has not been reported previously.

Adult↗

PubMed2000

Hypothetical pathophysiology of acute encephalopathy and encephalitis related to influenza virus infection and hypothermia therapy.

BACKGROUND: To establish a treatment strategy for acute encephalopathy and encephalitis associated with influenza virus infection, the pathophysiology of the disease was investigated through manifestations and laboratory findings of patients. PATIENTS AND METHODS: A child with central nervous system (CNS) complications during the course of influenza virus infection was analyzed in view of immunologic abnormalities. In addition, four children with acute encephalopathy and encephalitis were enrolled in the hypothermia treatment for the purpose of stabilizing the cytokine storm in the CNS. RESULTS: The CNS symptoms preceded the systemic progression to the failure of multiple organs (MOF) and disseminated intravascular coagulopathy (DIC). The mild hypothermia suppressed the brain edema on computed tomography (CT) scanning and protected the brain from the subsequent irreversible neural cell damage. CONCLUSION: The replicated viruses at the nasopharyngeal epithelium may disrupt the olfactory mucosa and gain access to the brain via the olfactory nerve system. The direct virus-glial cell interaction or viral stimulation of the glial cells induces the production and accumulation of the pro-inflammatory cytokines, especially tumor necrosis factor (TNF)-alpha, in the CNS. The cytokine storm results in neural cell damage as well as the apoptosis of astrocytes, due to the TNF-alpha-induced mitochondrial respiratory failure. The disruption of the blood-brain barrier progresses to the systemic cytokine storm, resulting in DIC and MOF. Mild hypothermia appears promising in stabilizing the immune activation and the brain edema to protect the brain from ongoing functional, apoptotic neural and glial damage and the systemic expansion of the cytokine storm.

Acute Disease↗

PubMed2000

Usefulness of serum fibrinogen degradation product-E in sporadic cases of classical hemolytic uremic syndrome.

BACKGROUND: Hemolytic uremic syndrome (HUS) associated with Shiga toxin (Stx)-producing Escherichia coli O157:H7 infection is one of the diseases causing acute renal failure in young children. Although HUS is still a serious disease in children, no reliable predictive markers for HUS nor markers of disease severity are available so far. Recently, we experienced a sporadic case of typical HUS caused by Stx-producing E. coli O157:H7 and detected, at the prodromal stage, a high level of serum fibrin/fibrinogen degradation product-E (FDP-E) fraction. METHODS: To assess the usefulness of FDP-E for the treatment of HUS in clinical practice, we retrospectively examined serum levels of FDP-E in 22 patients with bloody diarrhea with or without HUS. RESULTS: There were significantly increased levels of serum FDP-E in patients with HUS, but not in those without HUS. Furthermore, serum levels of FDP-E may correlate with disease severity in patients with HUS. CONCLUSIONS: These results suggest that serum levels of FDP-E may be a useful marker of HUS in clinical practice.

Biomarkers↗

PubMed2000

Predictors of coronary artery lesions after intravenous gamma-globulin treatment in Kawasaki disease.

OBJECTIVE: We evaluated the efficacy of intravenous gamma-globulin (IVGG) administration for children with Kawasaki disease to establish whether additional, more advanced therapy is needed in intractable cases. STUDY DESIGN: A total of 193 children with Kawasaki disease were studied retrospectively. Patients were admitted 3 to 7 days after the onset of the disease, and IVGG was administered. Laboratory measurements including white blood cell (WBC), neutrophil, and platelet counts and C-reactive protein (CRP) and albumin concentrations were determined before and 2 to 3 days after IVGG treatment. The progression of coronary artery lesions (CALs) was monitored by serial echocardiography until 30 days after treatment. RESULTS: Of 193 children, 24 (12.2 %) had CALs including transient dilatation. In contrast to the other measurements, the WBC count increased in 21 of 24 (87.5%) children with CALs after IVGG therapy. The patients with increased neutrophil count and CRP concentration after IVGG therapy also had CAL formation at a high rate (78.3% and 66.7%, respectively). Among children with normal coronary arteries, elevations of the WBC and neutrophil counts and CRP concentration were observed after IVGG therapy in only 3, 6, and 8 patients, respectively (specificity: 98.2%, 97.0%, and 95.3%, respectively). Furthermore, multiple logistic regression indicated that these variables were useful predictors of CALs in KD. CONCLUSION: Though the introduction of IVGG therapy has improved the prognosis of Kawasaki disease, approximately 10% of patients still develop CALs. The need for more aggressive therapy in IVGG-resistant cases can be recognized early by increases in the WBC and neutrophil counts and serum CRP concentration after IVGG administration.

Biomarkers↗

PubMed2000

Expression of histo-blood group antigens by lipopolysaccharides of Helicobacter pylori strains from asian hosts: the propensity to express type 1 blood-group antigens.

Past studies have shown that the cell surface lipopolysaccharides (LPSs) of the ubiquitous human gastric pathogen Helicobacter pylori (a type 1 carcinogen) isolated from people residing in Europe and North America express predominantly type 2 Lewis x (Le(x)) and Le(y) epitopes and, infrequently, type 1 Le(a), Le(b), and Le(d) antigens. This production of Lewis blood-group structures by H. pylori LPSs, similar to those found in the surfaces of human gastric cells, allows the bacterium to mimic its human niche. In this study, LPSs of H.pylori strains extracted from patients living in China, Japan, and Singapore were chemically and serologically analyzed. When compared with Western H.pylori LPSs, these Asian strains showed a stronger tendency to produce type 1 blood groups. Of particular interest, and novel observations in H.pylori, the O-chain regions of strains F-58C and R-58A carried type 1 Le(a) without the presence of type 2 Le(x), strains R-7A and H607 were shown to have the capability of producing the type 1 blood group A antigen, and strains CA2, H507, and H428 expressed simultaneously the difucosyl isomeric antigens, type 1 Le(b) and type 2 Le(y). The apparent proclivity for the production of type 1 histo-blood group antigens in Asian H.pylori LPSs, as compared with Western strains, may be an adaptive evolutionary effect in that differences in the gastric cell surfaces of the respective hosts might be significantly dissimilar to select for the formation of different LPS structures on the resident H.pylori strain.

ABO Blood-Group System↗

PubMed2000

Effect of IL-6 elevation in malignant pleural effusion on hyperfibrinogenemia in lung cancer patients.

BACKGROUND: The involvements of interleukin-6 (IL-6) and fibrinogen in cancer development were elucidated independently, irrespective of IL-6 activity to induce fibrinogen. This study was undertaken to clarify the clinicopathological association of these molecules in lung cancer patients with malignant pleurisy. METHODS: IL-6, fibrinogen and the related molecules in blood and pleural effusion of 38 patients were assayed at 3-day intervals. RESULTS: IL-6 levels were elevated in sera of 27 cases (71.1%) and in all the effusions with mean values of 20.5 and 9970.5 pg/ml, respectively. Their correlation in 22 cases who were examined on the same day was statistically strong (r = 0.902, p < 0.0001). Occasional elevations of tumor necrosis factor-alpha were independent of IL-6 elevation. Levels of plasma fibrinogen, fibrin(ogen) degradation products (FDP) and C-reactive protein (CRP) were more frequently elevated in the IL-6-elevated cases than those without IL-6 elevation. In all pleural effusions, fibrinogen levels were significantly decreased to <150 mg/dl with large elevations of FDP level. Immunocytologically, IL-6 was detected in cancer cells in 16 cases of adenocarcinoma in addition to host pleural cells, but its cellular positivity was not reflected in the IL-6 level in each pleural effusion. CONCLUSION: Compared with lung cancer patients without malignant pleurisy, IL-6, fibrinogen, FDP and CRP levels in patients with malignant pleurisy were increased more frequently in their peripheral blood. These were basically attributed to systemic leakage of IL-6 from the affected pleural cavity, in which plasma fibrinogen induced in response to serum IL-6 was exudated and degraded predominantly to FDP.

Adult↗

PubMed2000

[Why there were few isolations of tubercle bacilli in young children with pulmonary tuberculosis?].

We retrospectively evaluated the factors influencing the isolation of tubercle bacilli in 51 children under 14 years of age with pulmonary tuberculosis who were admitted to Yokohama City University Hospital from 1975 to 1998. Young children (0-6 years of age) with pulmonary tuberculosis were significantly less positive by smear and culture than elder children (7-14 years of age) with pulmonary tuberculosis. According to the Japanese Society for Tuberculosis classification of finding on chest X-ray film for pulmonary tuberculosis, the culture-positive patients with type II (cavitary lesions) were found in all, the culture-positive patients with type III (non-cavitary lesions) in 39.3%, and the culture-positive patients with type H (hilar and mediastinal lymphadenopathys) in 35.3%. Patients with cavitary lesions (type II) were significantly more positive by smear and culture than patients with non-cavitary lesions (type III + type H). Only 15.8% of the young children with pulmonary tuberculosis had received BCG vaccine and all had non-cavitary lesions (type III and type H). But, 84.6% out of the older children had received BCG vaccine and half had cavitary lesions. Taken together, the result was that there were few isolation of tubercle bacilli in young children with pulmonary tuberculosis because they had non-cavitary tuberculosis without delayed-type hypersensitivity to tubercle bacilli.

Adolescent↗

PubMed2000

Apolipoprotein E epsilon3 allele is not a risk factor of schizophrenia: a study of 314 Japanese patients.

The association between apolipoprotein E (ApoE) alleles and schizophrenia has remained controversial. A recent report claiming that ApoE epsilon3 Taiwan Chinese carriers have an increased risk of schizophrenia prompted us to investigate the allele frequency in a large group of Japanese schizophrenic patients. Serum samples were obtained from 314 schizophrenic patients and 188 controls in Japan and examined using isoelectric focusing/immunoblotting. There were no significant differences in ApoE allele frequencies between schizophrenic patients and controls and in the odds ratios for schizophrenia among the epsilon2, epsilon3 and epsilon4 carriers. In contrast to the report from Taiwan, our findings and results of the majority of previous studies suggest no effects of ApoE alleles on the development of schizophrenia.

Adult↗

PubMed2000

Insulin-degrading enzyme exists inside of rat liver peroxisomes and degrades oxidized proteins.

Insulin-degrading enzyme (IDE) was detected by immunoblot analysis in highly purified rat liver peroxisomes. IDE in the peroxisomal fraction was resistant to proteolysis by trypsin and chymotrypsin under conditions where the peroxisomal membranes remained intact. After sonication of the peroxisomal fraction, IDE was recovered in the supernatant fraction. Further, the localization of IDE in the peroxisomes was shown by immunoelectron microscopy. In addition, IDE isolated from peroxisomes degraded insulin as well as oxidized lysozyme as a model substrate for oxidized proteins. These results suggest that IDE exists in an active form in the matrix of rat liver peroxisomes and is involved in elimination of oxidized proteins in peroxisomes.

Animals↗

PubMed2000

The 70-kDa peroxisomal membrane protein (PMP70), an ATP-binding cassette transporter.

The 70-kDa peroxisomal membrane protein (PMP70) is one of major components of peroxisomal membranes. In rodents, PMP70 is markedly induced by administration of hypolipidemic agents in parallel with peroxisome proliferation and the induction of peroxisomal fatty acid beta-oxidation enzymes. PMP70 is an ATP-binding cassette transporter, identified for the first time in intracellular membranes of eukaryotic cells. The authors' recent studies suggest that PMP70 is synthesized on free polysomes and posttranslationally inserted into peroxisomal membranes, and assembles as dimeric or oligomeric forms on peroxisomal membranes. PMP70 is suggested to be involved in metabolic transport of long-chain acyl-CoA across peroxisomal membranes.

ATP-Binding Cassette Transporters↗