Biomedical subjects

K Maeda

Publications and source records attributed to K Maeda.

At least 343 records · Page 19Linked to original sources

PubMed1998

Importance of glucose-6-phosphate dehydrogenase in the adaptive response to hydrogen peroxide in Saccharomyces cerevisiae.

Glucose-6-phosphate dehydrogenase (G6PDH)-deficient cells of Saccharomyces cerevisiae showed increased susceptibility and were unable to induce adaptation to oxidative stress. Historically, mainly in human erythrocytes, it has been suggested and accepted that decreased cellular GSH, due to loss of the NADPH-dependent activity of glutathione reductase (GR), is responsible for the increased sensitivity to oxidative stress in G6PDH-deficient cells. In the present study we investigated whether the increased susceptibility and the inability to induce adaptation to H2O2 stress of G6PDH-deficient yeast is caused by incompleteness of glutathione recycling. We constructed G6PDH- and GR-deficient mutants and analysed their adaptive response to H2O2 stress. Although G6PDH-deficient cells contained comparable amounts of GSH and GR activity to wild-type cells, GSSG was not reduced efficiently, and intracellular GSSG levels and the ratio of GSSG to total glutathione (GSSG/tGSH) were higher in G6PDH-deficient cells than in wild-type. On the other hand, GR-deficient cells showed a susceptibility identical with that of wild-type cells and induced adaptation to H2O2 stress, even though the GSSG/tGSH ratio in GR-deficient cells was higher than in G6PDH-deficient cells. These results indicate that incompleteness of glutathione recycling alone is not sufficient to account for the increased sensitivity and inability to induce adaptation to H2O2 stress of G6PDH-deficient yeast cells. In S. cerevisiae, G6PDH appears to play other important roles in the adaptive response to H2O2 stress besides supplying NADPH to the GR reaction.

Adaptation, Physiological↗

PubMed1998

Characterization of anti-feline CD8 monoclonal antibodies.

We generated three monoclonal antibodies (mAbs) (2D7, 10C7 and 12A3) reactive to the alpha-chain of feline CD8 (fCD8) molecule. Further we showed that reference anti-fCD8 mAbs, FT2, 3.357 and vpg9 recognize the beta-chain, alpha-chain and alphabeta-complex epitope, respectively. Flow cytometric analysis using these mAbs suggested that fCD8alpha(+)beta(-) cells were present in lymphocytes of spleen, but not significantly in those of thymus, lymph nodes and peripheral blood of normal kittens.

Animals↗

PubMed1998

Hyperalgesia and decreased neuronal nitric oxide synthase in diabetic rats.

To evaluate the role of nitric oxide synthase (nNOS) in the pathogenesis of diabetic neuropathy, we investigated nociception and nNOS expression in dorsal root ganglion (DRG) of rats with streptozocin-induced diabetes. Paw withdrawal threshold to noxious mechanical stimuli was decreased in both L-NAME-treated and diabetic rats. The number of NADPH-diaphorase positive neurons was significantly decreased in untreated diabetic compared with control rats. Decreased expression of nNOS protein was confirmed by immunoblotting. Insulin treatment completely prevented decreases in withdrawal threshold and nNOS expression. Cyclic GMP content paralleled nNOS expression in experimental animals. These results suggest that decreased nNOS-cGMP system in DRG may play a role in the pathogenesis of diabetic sensory neuropathy.

Animals↗

PubMed1998

Primary small cell carcinoma of the esophagus: flow cytometric analysis and immunohistochemical staining for the p53 protein and proliferating cell nuclear antigen.

BACKGROUND AND OBJECTIVES: The purpose of this study was to determine the clinical course and effects of histopathologic characteristics of specific tumors including DNA contents and immunohistochemical aspects in patients with small cell carcinoma of the esophagus. METHODS: Medical records of 4 patients who presented with small cell carcinoma of the esophagus were retrospectively reviewed. RESULTS: DNA aneuploidy was observed in 2 cases. Staining for the p53 product was positive in all cases. The average proliferating cell nuclear antigen (PCNA) labeling rate (LR) was 77.6% (64.0-90.8%). The estimated median survival was 42 days for all patients. Distant metastases were observed in 2 of the 4 patients. CONCLUSIONS: Higher PCNA LR of small cell carcinoma may be an unfavorable characteristic of biological behavior. Patients with disseminated disease should have symptomatically palliative operation combined with chemotherapy.

Aged↗

PubMed1998

Neutrophils responded to immobilized lipopolysaccharide in the absence of lipopolysaccharide-binding protein.

Lipopolysaccharide (LPS) in solution primes neutrophils for enhanced release of superoxide in response to N-formyl-methionyl-leucyl-phenylalanine. We show that LPS immobilized on polystyrene or polypropylene acted on neutrophils by a mechanism different from that of LPS in solution. Coating the surface with 1% plasma, either before coating with LPS (plasma/LPS) or after coating with LPS (LPS/plasma), was essential to induce the LPS response in neutrophils. However, plasma could be replaced by fibrinogen, type I collagen or type IV collagen, or, to a lesser extent, by fibronectin or vitronectin, which was not true for LPS in solution. About 20% of the LPS added was immobilized on the plastic surfaces, based on its ability to adsorb anti-LPS antibody after extensive washing. The amount of soluble LPS that might have been released from surfaces during the incubation with neutrophils was too low to account for the priming by immobilized LPS. About 13-20 min was needed for neutrophils to become primed after incubation with immobilized LPS. Immobilized LPS induced up-regulation of CD11b/CD18 and latent alkaline phosphatase and also enhanced the adhesive response of neutrophils. Priming by immobilized LPS was inhibited by anti-CD14 antibody or by treatment of neutrophils with the LPS antagonist LA-14-PP. When immobilized LPS was treated with anti-LPS-binding protein (LBP) antibody, the response of neutrophils to LPS/plasma was inhibited but the response to plasma/LPS or fibrinogen/LPS was not. Thus, the LPS in plasma/LPS or fibrinogen/LPS acted on neutrophils in an LBP-independent manner. We conclude that the CD14-dependent LPS receptor system of neutrophils was capable of working in the absence of LBP, but only when LPS was immobilized on a surface coated with protein.

Acute-Phase Proteins↗

PubMed1998

Excitatory amino acids act on the median eminence nerve terminals to induce gonadotropin-releasing hormone release in female rats.

The present study is designed to examine the terminal regulation of gonadotropin-releasing hormone (GnRH) release by excitatory amino acids in the median eminence of ovariectomized (OVX) rats. In in vitro experiments, median eminence tissues were superfused in the medium containing glutamate or excitatory amino acid agonists, such as N-methyl-d,l-aspartate or kainate. These drugs induced a Ca2+-dependent GnRH release from median eminence fragments. The agonists also stimulated GnRH release from superfused synaptosome prepared from the median eminence tissues in a Ca2+-dependent manner. In the immunocytochemical study, immunoreactivity for glutamate or its ionotropic receptor subtypes, such as NR1, GluR1, GluR2/3, GluR6/7, and KA2, was examined in the median eminence of OVX rats under electron microscopy. Immunoreactivities for glutamate or its receptor subtypes were observed on the nerve terminals, most of which were located in close proximity to the other nerve terminals without forming synaptic contacts. In addition, quite a few synaptic contacts which were immunopositive for GluR1, GluR2/3, KA2, or glutamate were found in this area. The present results indicate that excitatory amino acids stimulate GnRH release by acting at the nerve terminals of the median eminence in a Ca2+-dependent manner in the absence of gonadal steroid. The effect of excitatory amino acids in this area might be mediated by glutamate receptors mainly in nonsynaptic fashion, such as by volume transmission.

Animals↗

PubMed1998

Cerebral blood flow changes in the primary motor and premotor cortices during hyperventilation.

The aim of this study was to clarify the regional differences in cerebral blood flow (CBF) change during hyperventilation by using H2(15)O and positron emission tomography (PET). Eight healthy volunteers (age: 63.0 +/- 8.9 yr.) were studied. Regional CBF was measured by the H2(15)O autoradiographic method and PET. Statistical parametric maps (SPM) and conventional regions of interest (ROI) analysis were used for estimating regional CBF differences in the normocapnic state with normal breathing and the hypocapnic state induced by hyperventilation. Total CBF decreased during the hypocapnic state. The SPM revealed that primary motor and premotor cortices were significantly activated by hyperventilation. In these areas absolute CBF values were significantly higher than those in the temporal, occipital and parietal lobes in the hypocapnic state, but there were no significant regional differences in the normocapnic state. In the hypocapnic state induced by hyperventilation, the primary motor and premotor CBF shows combined changes with vasoreaction to hypocapnia and increase in activation due to hyperventilation.

Aged↗

PubMed1998

Hypercalcemia associated with parathyroid hormone-related protein produced by B-cell type primary malignant lymphoma of the kidney.

A patient with primary non-Hodgkin's (B-cell type) lymphoma of the kidney developed hypercalcemia at the terminal stage of the disease. Although the plasma parathyroid hormone level was low, urinary cyclic AMP excretion was elevated. Serum osteocalcin (BGP) was suppressed and the plasma level of 1,25(OH)2D was within the normal range. Serum concentrations of PTH-related protein (PTHrP)-like immunoreactivity (PRP-LI) were elevated, and the tissue concentration of PRP-LI in the postmortem lymph node showed high level along with elevated serum PRP-LI, furthermore the production of PTHrP by the tumor was demonstrated by immunohistochemistry and Northern blotting analysis. These findings indicate that the hypercalcemia of the patient was caused by the PTHrP-producing B-cell lymphoma. Hypercalcemia was restored to normocalcemia by bisphosphonate treatment. Our case will add further information on humoral hypercalcemia in B-cell lymphoma, which rarely has been demonstrated to produce PTHrP.

Autopsy↗

PubMed1998

A genetic locus susceptible to the overt proteinuria in BUF/Mna rat.

The BUF/Mna (BUF) strain is a high-proteinuria line of rats, and virtually all rats develop overt proteinuria by the age of 20 weeks. Genetic analysis revealed that proteinuria susceptibility was determined principally by two autosomal recessive genes. These findings prompted us to perform genetic mapping of the genes. (BUF/Mna x WKY/NCrj) F1 x BUF/Mna backcross rats were raised and maintained for 40-60 weeks to detect proteinuria. DNAs were extracted from ears of these rats and were examined by linkage study with polymerase chain reaction (PCR) with 132 microsatellite markers. Fifty-three out of 167 rats developed proteinuria. DNAs of 51 out of these 53 rats showed homozygous BUF/BUF genotype in the D13Mgh4 and D13N1 markers located on Chromosome (Chr) 13. The D13Rat1, D13Mgh2, D13Rat13, D13Mgh3, Syt2, Ren, D13Rat25, D13Mit2, D13Mgh5, and D13N2 markers located on the chromosome also showed statistically significant linkage to the development of proteinuria, whereas the other 110 markers showed no linkage. Here we report that a proteinuria-susceptible gene, Pur1, resides on a region flanked by the loci D13Mgh3 and D13Mgh4 on Chr 13.

Animals↗

PubMed1998

Advanced glycation end products co-localized with astrocytes and microglial cells in Alzheimer's disease brain.

In the previous study [Takeda et al. (1996) Neurosci Lett 221: 17-21], we reported that the advanced glycation end products (AGEs) in the external space of neuronal perikarya (extraneuroperikaryal AGE deposits) were significantly abundant in the Alzheimer's brain. In this study, we investigated the spatial relationship of the extraneuroperikaryal AGE (carboxymethyllysine and pentosidine) deposits in astrocytes and microglial cells in the Alzheimer's disease brain using double immunolabelling for AGEs and astrocyte or microglial cell markers. Most of the extraneuroperikaryal AGE deposits were co-localized with glial fibrillary acidic protein-positive astrocytes. AGE deposit-bearing astrocytes also contained Gomori-positive granules. Furthermore, some of the extraneuroperikaryal AGE deposits were co-localized with microglial cells. These extraneuroperikaryal AGEs may activate astrocyte and microglia, and play a role in pathogenesis of Alzheimer's disease.

Aged↗

PubMed1998

A new quadruple therapy for the eradication of Helicobacter pylori. Effect of pretreatment with omeprazole on the cure rate.

To elucidate whether pretreatment with omeprazole decreases the cure rate of Helicobacter pylori infection with a new quadruple therapy, and thus, whether this pretreatment should not be used in clinical practice, we conducted a randomized trial. Ninety patients with chronic peptic ulcer disease and nonulcer dyspepsia, with biopsy-proven H. pylori infection were randomly assigned to the two following regimens: Group 1 (n = 45) received omeprazole 20 mg once daily for 2 weeks (days 1-14), and 500 mg amoxicillin granules and 250 mg metronidazole thrice daily, and roxithromycin 150 mg twice daily for 1 week (days 8-14), Group 2 (n = 45) received the same antibiotic treatment as group 1 for 1 week (days 1-7), in addition to omeprazole treatment for 2 weeks (days 1-14). Four weeks after the treatment ended, endoscopy was repeated, with two biopsy specimens each taken from the antrum and the corpus (total of four specimens) for a urease test, histological analysis, and culture to establish cure of infection. A patient was regarded as cured only if all three methods gave negative results for H. pylori. In the intention-to-treat analysis, 42 of 45 patients (93.3%; 95% confidence intervals [CI], 81.7%-98.6%) in group 1 were cured compared with 43 of 45 patients (95.6%; 95% CI, 84.9%-99.5%) in group 2. In the per-protocol analysis, the corresponding figures were 42/44 (95.5%; 95% CI 84.5%-99.4%) and 43/44 (97.7%; 95% CI, 88.0%-99.9%). There were no significant differences in the cure rate between the two groups on either analysis. All patients, except for one who had an allergic reaction, completed the treatment regimens. Fifty to sixty percent of the patients had no side effects while the rest had mild to moderate side effects. The new quadruple therapy consisting of omeprazole, amoxicillin, metronidazole, and roxithromycin appears suitable for use in clinical practice, as the cure rate was 95% and no severe side effects were observed. Pretreatment with omeprazole did not reduce the cure rate for this new quadruple therapy.

Adult↗

PubMed1998

p53 protein overexpression as a predictor of the response to chemotherapy in gastric cancer.

This study was performed to evaluate p53 overexpression as a predictor of the response to chemotherapy of patients with gastric cancer. The subjects comprised 20 patients with Stage IV gastric cancer and three with locally recurrent lesions, all of whom were treated with 5-fluorouracil (5-FU) plus cisplatin (CDDP) for 4 weeks. Of the total 23 patients there were 10 responders; 2 showing complete response (CR) and 8, partial response (PR). Specimens obtained by endoscopic biopsy were immunohistochemically stained using anti-p53 protein and bcl-2 protein antibody. Of the 10 responders, 7 demonstrated negative p53 staining, and of the 13 nonresponders, 11 demonstrated positive p53 staining (P = 0.013). Tissue from 3 of the responders and 7 of the nonresponders that stained for bcl-2 were positive prior to chemotherapy; however, there was no association between bcl-2 staining and chemotherapeutic effect. In conclusion, immunohistochemical identification of p53 in pretreatment tissue may represent a useful predictor for chemotherapeutic outcome in patients with gastric cancer.

Adult↗

PubMed1998

In vitro recombination of feline herpesvirus type 1.

We investigated the possibility of in vitro recombination of three different strains of feline herpesvirus type 1 (FHV-1), a virulent strain (C7805), a vaccine strain (F2), and a candidate vaccine strain with a deletion in the thymidine kinase gene (C7301dlTK). The results showed that recombination within different genotypes of FHV-1 strains could occur at a relatively high frequency ranging from 10.1% to 21.5% in vitro. These results indicate the generation of multiple mutant viruses by in vitro recombination experiments. The possibility for generating a virulent virus or novel type of FHV-1 by recombination in vivo is discussed.

Animals↗

PubMed1998

Construction of a recombinant feline herpesvirus type 1 expressing Gag precursor protein of feline immunodeficiency virus.

We constructed a deletion mutant of feline herpesvirus type 1 (FHV-1) and a recombinant FHV-1. The deletion mutant is the virus with a region (367 bp) deleted from the start codon of thymidine kinase (TK) gene to the SmaI site within the TK gene, and the other is a recombinant FHV-1 expressing Gag protein of feline immunodeficiency virus (FIV), in which a cDNA encoding the Gag protein of FIV was inserted at the TK deletion site of the former deletion mutant. These viruses were designated as C7301ddlTK and C7301ddlTK-gag, respectively. Growth kinetics of these viruses in Crandell feline kidney cells was similar to that of the parent C7301 strain. By immunoblot analysis, C7301 ddlTK-gag was confirmed to express the FIV Gag precursor protein in the cells.

Alphaherpesvirinae↗

PubMed1998

Plasma brain natriuretic peptide as a biochemical marker of high left ventricular end-diastolic pressure in patients with symptomatic left ventricular dysfunction.

BACKGROUND: Plasma atrial natriuretic peptide (ANP), mainly from the atrium, brain natriuretic peptide (BNP), mainly from the ventricle, norepinephrine (NE), and endothelin-1 (ET-1) levels are increased with the severity of congestive heart failure (CHF). Although a close correlation between the left ventricular end-diastolic pressure (LVEDP) and plasma ANP in patients with left ventricular dysfunction has been reported, it is not yet known which cardiac natriuretic peptide is a better predictor of high LVEDP in patients with CHF. METHODS: To investigate the biochemical predictors of the high LVEDP in patients with left ventricular dysfunction, we measured plasma ANP, BNP, NE, and ET-1 levels and the hemodynamic parameters in 72 patients with symptomatic left ventricular dysfunction. Stepwise multivariate regression analyses were also used to determine whether the plasma levels of ANP, BNP, NE, and ET-1 could predict high LVEDP. RESULTS: Although significant positive correlations were found among the plasma levels of ANP, BNP, ET-1, and NE and the LVEDP, only BNP (p = 0.0001) was an independent and significant predictor of high LVEDP in patients with CHF. In all eight patients with severe CHF measured for hemodynamics before and after the treatments, the plasma BNP levels decreased in association with the decrease of LVEDP, whereas other factors increased in some patients despite the decrease of LVEDP. CONCLUSIONS: These findings suggest that plasma BNP is superior to ANP as a predictor of high LVEDP in patients with symptomatic left ventricular dysfunction.

Adult↗

PubMed1998

Potential paracrine role of the pericardium in the regulation of cardiac function.

OBJECTIVE: Both coronary and endocardial endothelium regulate cardiac contractile function via paracrine pathways. We investigated whether pericardial fluid (PF) and pericardial mesothelial cells (PMC) could exert a similar paracrine action. METHODS: Both PF and PMC were extracted from sheep pericardial space. Endothelin-1, prostaglandins and atrial natriuretic factor were measured in PF in vivo. In the other hand, PMC were grown on T-75 flasks and microcarrier beads to investigate endothelin-1, nitric oxide and prostaglandin pathways in vitro. In addition, effects of PF and PMC effluent were tested on adult rat cardiac myocyte contraction in vitro. RESULTS: In vitro, cultured PMC expressed endothelin-1 mRNA but not the endothelial nitric oxide synthase III, and released endothelin-1 and prostaglandins. Both PF and cultured PMC superfusate induced a potent, rapidly reversible decrease in the shortening of isolated rat cardiac myocytes. This effect was not associated with changes in intracellular calcium. In vivo, prostaglandins, atrial natriuretic factor and endothelin were present in PF. A greater concentration of atrial natriuretic factor was present in PF than in serum, suggesting molecular diffusion from the myocardium to PF. Preliminary results show that the instillation of vasoactive agents into the pericardial space of dogs rapidly alter coronary and systemic vascular tone, consistent with a molecular diffusion of these substances from PF into the myocardium and circulation. CONCLUSIONS: In addition to its mechanical role, the pericardium may contribute to the integration and the regulation of cardiovascular function via a paracrine mechanism.

Animals↗

PubMed1998

An immunohistochemical study of the behavior of cells expressing interleukin-1 alpha and interleukin-1 beta within experimentally induced periapical lesions in rats.

Cells expressing interleukin-1 (IL-1) were examined in rat periapical lesions using immunohistochemical methods. During the acute phase, both IL-1 alpha- and IL-1 beta-expressing cells were observed adjacent to many osteoclasts that contained large cytoplasms, and consequently the periapical lesions tended to expand. However, the number of IL-1 beta-expressing cells was about twice that of IL-1 alpha-expressing cells during the same period. On the other hand, there were significantly less IL-1 beta-expressing cells during the chronic phase and consequently a significant expansion of the periapical lesions was not seen. Furthermore, IL-1 alpha- and IL-1 beta-expressing cells were located far from the bone surfaces, whereas a fibroblastic cell layer lay between the IL-1-expressing cells and the bone surfaces. Both IL-1 alpha and IL-1 beta were mainly expressed by macrophages. In addition, after the percolated application of formocresol to experimentally induced periapical lesions, numerous macrophages expressing IL-1 beta became conspicuous within the vicinity of the extensive bone resorption sites. These results suggest that macrophages expressing IL-1 beta may play an important role in the activation and recrudescence of osteoclastic bone resorption, and this may be due to their localization close to the bone resorption sites noted within experimental periapical lesions.

Alveolar Bone Loss↗

PubMed1998

Delusions of oral parasitosis.

1. The authors present a case of a 76-year-old man with delusional disorders, somatic type, who strongly believed that his mouth was infested with worms. 2. Such a case has not previously been described in the literature and the authors refer to the syndrome as delusions of oral parasitosis. 3. The authors examined the effect of pimozide, whose efficacy on delusional skin parasitosis has been proven. Taking the neuroleptic at a dose of 2 mg daily relieved the symptoms.

Aged↗