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Biomedical subjects

M Higuchi

Publications and source records attributed to M Higuchi.

At least 181 records · Page 10Linked to original sources
PubMed1994

Improved method for the analysis of ascorbic acid in plasma by high-performance liquid chromatography with electrochemical detection.

We improved the analytical method for the detection of ascorbic acid in plasma by high-performance liquid chromatography (HPLC) with an electrochemical detector (ECD) to be more selective and rapid than the protocol previously used. Main improvements are as follows. Applied potential of ECD to obtain the maximal response for ascorbic acid was +450 mV versus Ag/AgCl, but it was reduced to +350 mV. In that condition, uric acid did not respond to ECD, and only ascorbic acid was detected. EDTA contained in sample extraction/stabilizing solution gave the peak after the ascorbic acid. The addition of EDTA (0.2 mM) to the mobile phase eliminated the EDTA peak. These two improvements gave the chromatogram in which the peak that appeared from the plasma sample was only ascorbic acid, and shorten the sample run time. Ascorbic acid in plasma was unstable even though the plasma was treated with methanol/EDTA: it decreased from 1.5 h at 4 degrees C. However, the treated sample, which was placed at -14 degrees C until the analysis was performed, gave the reliable ascorbic acid value at least up to 6 h. The data obtained from the HPLC-ECD method was consistent with those from the hydrazine method.

Ascorbic Acid↗
PubMed1994

Effect of tumor necrosis factors, interferons, interleukins, and growth factors on the activation of NF-kappa B: evidence for lack of correlation with cell proliferation.

The nuclear transcription factor NF-kappa B has been identified as a critical component in signal transduction pathways. We used an electrophoretic gel mobility shift assay to examine the activation of NF-kappa B in human U-937 cells treated with tumor necrosis factor (TNF), lymphotoxin (LT), interferons (IFN)-alpha, IFN-beta, and IFN-gamma, interleukins (IL)-1 beta, IL-4, and IL-6, leukemia inhibitory factor (LIF), basic fibroblast growth factor (FGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and transforming growth factor-beta (TGF-beta). Only TNF, LT, and IL-1 activated NF-kappa B. Since interferons have been shown to induce TNF receptors and potentiate TNF-mediated cellular responses, we also measured the effect of interferons on TNF-induced activation of NF-kappa B. Under our conditions, all three IFNs potentiated the cytotoxic effects of TNF but had no effect on the TNF-dependent NF-kappa B activation. These results suggest overall that the activation of NF-kappa B is not a generalized mediator of signal transduction of most cytokines and also that NF-kappa B activation is not sufficient for antiproliferative effects mediated through certain cytokines.

Base Sequence↗
PubMed1994

[Necessity of cerebral angiography in thunderclap headache patients who show no evidence of subarachnoid hemorrhage: investigation of 350 cases].

PURPOSE: The necessity of cerebral angiography was assessed in patients with thunderclap headache in whom subarachnoid hemorrhage had been ruled out on CT findings and the color of cerebrospinal fluid (CSF). SUBJECTS AND METHODS: The subjects of this study were 350 patients with thunderclap headache in whom subarachnoid hemorrhage was ruled out at our clinic based on CT findings and the color of CSF. The time span from the onset of thunderclap headache to the first visit to our clinic ranged from 1 to 9 days (mean: 2.5 days). The ages of the patients ranged from 22 to 64 years. 147 were male and 203 female. All patients underwent CT angiography. Percutaneous cerebral angiography was also performed in cases in which cerebral aneurysms were suspected on CT angiography or the CSF cell count was elevated (over 10/3mm3 on white blood cells). RESULTS: (1) Of the 350 patients, 162 were suspected to have cerebral aneurysms when examined by CT angiography. When these 162 patients were examined by percutaneous cerebral angiography, cerebral aneurysms were found in 34 patients (9.7%). (2) Four patients had an elevated CSF cell count. Cerebral aneurysms were found in all these patients. (3) Of the 34 patients with cerebral aneurysms, 31 consented to and underwent direct surgery. Localized subarachnoid hemorrhage around their aneurysms was found in seven (22.6%) of these 31 patients intraoperatively. Elevation in CSF cell count was shown in three of these patients. CONCLUSION: Even when CT and CSF studies reveal no abnormalities in the early stage after the onset of thunderclap headache, subarachnoid hemorrhage can not be ruled out. Therefore, cerebral angiography is recommended in patients with thunderclap headache.

Adult↗
PubMed1994

[A case of pulmonary alveolar proteinosis with increased IgE and CEA].

We report here a case of pulmonary alveolar proteinosis with significantly increased IgE and CEA values, in both serum and bronchoalveolar lavage fluid. A 35-year-old man presented with exertional dyspnea, diffuse abnormal shadows on radiological examination of the chest and physiologic evidence of a restrictive lung disease. Bronchoalveolar lavage and transbronchial lung biopsy proved that the patient was suffering from pulmonary alveolar proteinosis. He had worked as a landscape gardener for the past 2 years, and had been exposed to insecticides. IgE and CEA levels were significantly elevated in both serum and bronchoalveolar lavage fluid. After whole lung lavage, general status improved remarkably and serum CEA fell to the normal range. The serum IgE level was, however, reduced by only half. Proliferating type II epithelial cells in pulmonary alveolar proteinosis have been suggested to produce CEA. However, the cause of the increased IgE level remains unknown. This case report suggests that some abnormal immunological events, leading to hyperproduction of IgE, could play a role in the onset of pulmonary alveolar proteinosis.

Adult↗
PubMed1993

RNA editing of AMPA receptor subunit GluR-B: a base-paired intron-exon structure determines position and efficiency.

A functionally critical position (Q/R site) of the AMPA receptor subunit GluR-B is controlled by RNA editing that operates in the nucleus, since in brain and clonal cell lines of neural origin, unspliced GluR-B transcripts occur edited in the Q/R site CAG codon and, additionally, in intronic adenosines. Transfection of GluR-B gene constructs into PC12 cells revealed that the proximal part of the intron downstream of the unedited exonic site is required for Q/R site editing. This intron portion contains an imperfect inverted repeat preceding a 10 nt sequence with exact complementarity to the exon centered on the unedited codon. Single nucleotide substitutions in this short intronic sequence or its exonic complement curtailed Q/R site editing, which was recovered by restoring complementarity in the respective partner strand. Base conversion in the channel-coding region of GluR-B directed by base paired sequences may be executed by a ubiquitous nuclear adenosine deaminase specific for double-stranded RNA.

Adenosine Deaminase↗
PubMed1993

Ex vivo effect of insulin on normal and diabetic rat hearts hypoperfused with norepinephrine.

The effect of ex vivo insulin on contractile and energy metabolism dysfunctions was examined during hypoperfusion (0.6 ml/min per g heart weight) with 10(-6) M norepinephrine in isolated non-diabetic and streptozotocin-diabetic rats hearts. Insulin (2 mU/min per g heart weight) was infused for 15 min before as well as during 60-min hypoperfusion. Insulin significantly reduced the elevated diastolic tension in diabetic hearts (from 3.8 to 0.7 delta g), but not in non-diabetic hearts (from 1.4 to 1.2 delta g). Insulin partly improved the ATP decrease in the subendocardium of the left ventricle of the diabetic hearts (from 3.5 to 10.2 mumol/g dry weight) but did not affect non-diabetic hearts (from 6.9 to 6.8 mumol/g dry weight). Insulin also partly improved the creatine phosphate decrease and the inorganic phosphate increase in diabetic hearts only. Lactate accumulation was greater in non-diabetic than in diabetic hearts, even in the presence of insulin (77 vs. 45 mumol/g dry weight). The results indicate that acute intracoronary application of insulin in diabetic hearts improves hypoperfusion with norepinephrine injury to a level above that of non-diabetic hearts, but does not improve a less severe injury in non-diabetic hearts.

Animals↗
PubMed1993

P80 form of the human tumor necrosis factor receptor is involved in DNA fragmentation.

Two different types of TNF receptors with molecular masses of 60 kDa (p60) and 80 kDa (p80) have been identified. TNF is known to cause DNA fragmentation in certain tumor cell lines but the role of p60 and p80 in this action is not understood. In the present study, we examined the role of these receptors in TNF-induced DNA fragmentation. Treatment of U-937 cells with phorbol ester caused downregulation of both types of TNF receptors and this was accompanied by disappearance of the TNF-induced DNA fragmentation. The removal of phorbol ester led to two time-dependent events: (1) the rapid regeneration of the p80 form but not the p60 form of the TNF receptor; and (2) the reappearance of TNF-induced DNA fragmentation. These results suggest that the p80 receptor could mediate the TNF-induced DNA fragmentation.

Cells, Cultured↗
PubMed1993

Okadaic acid induces down-modulation and shedding of tumor necrosis factor receptors. Comparison with another tumor promoter, phorbol ester.

Protein kinase C modulates the receptor for tumor necrosis factor (TNF) in wide variety of different cell types. However, there is no information about the role of phosphatases in the regulation of the TNF receptor. In this report, we investigated the effect of okadaic acid, an inhibitor of serine/threonine phosphatases, on TNF receptors in U-937 cells, a human histiocytic lymphoma cell line. In our study okadaic acid induced a dose- and time-dependent down-modulation of TNF receptors. On exposure of cells to 0.5 microM okadaic acid for 60 min at 37 degrees C, a complete down-regulation of the receptors was observed, but no modulation occurred at 4 degrees C. Scatchard analysis of the binding data on U-937 cells revealed that okadaic acid caused a decrease in the high affinity cell surface receptor number without a significant change in the affinity constant. The down-regulation of the TNF receptor by okadaic acid was not specific to U-937 cells, as it was also observed with several other cell types. Okadaic acid had no significant effect on the internalization of the receptor, but it did induce a shedding of the TNF receptor from its cell surface. On exposure of cells to okadaic acid, a dose- and time-dependent increase in the 40-kDa polypeptide was detected in the medium with anti-p80 antibodies by Western blot analysis. The secreted product was also found to bind TNF. The mechanism by which okadaic acid down-modulates the TNF receptor appears to be quite different from that of phorbol ester. First, okadaic acid synergistically potentiated the effect of phorbol ester. Second, the phorbol ester-mediated down-modulation could be blocked by H-7 and staurosporine, well known protein kinase C inhibitors, but these inhibitors had no effect on okadaic acid-mediated response. Third, phorbol ester-mediated down-modulation of the TNF receptor was reversible after removal of the agent, but the response mediated through okadaic acid was irreversible. Fourth, the TNF receptor was down-regulated by okadaic acid but not by phorbol ester in cells depleted of protein kinase C. Thus, overall, our results demonstrate that serine/threonine phosphatases can down-modulate and induce shedding of TNF receptors by a mechanism distinct from that of protein kinase C.

Down-Regulation↗
PubMed1993

Chromium and tritiated thymidine releases from target cells are differential events in human monocyte/macrophage-mediated cytotoxicity.

Cytotoxic properties of human activated macrophages were investigated by measuring both 51Cr and [3H]TdR releases from prelabeled target cells. The kinetic study of macrophage-mediated cytotoxicity indicated that 51Cr and [3H]TdR releases showed a distinct time course. Next, when [3H]TdR release was measured as a parameter for cytotoxicity, pretreatment of activated macrophages with either actinomycin D or emetine remarkably decreased their cytotoxicity in a dose-dependent manner. In contrast, the pretreatment with these inhibitors had little effect on 51Cr release. Furthermore, the addition of Zn2+ in the assay medium caused the decrease in [3H]TdR release but not 51Cr release from the target cells. Taken together, our findings indicate that 51Cr and [3H]TdR releases from the target cells are induced by activated macrophages through different cytotoxic mechanisms; the former does not require RNA and protein syntheses in macrophages during coculture, whereas the latter requires them. Our findings also suggest that macrophage-derived nuclease may play an important role for inducing [3H]TdR release from the target cells.

Chromium Radioisotopes↗
PubMed1993

Expression of tenascin in human gliomas: its relation to histological malignancy, tumor dedifferentiation and angiogenesis.

The immunohistochemical distribution of tenascin (TN), fibronectin (FN), and laminin (LN) was investigated in 56 human gliomas (8 astrocytomas, 15 anaplastic astrocytomas, and 33 glioblastomas) with regards to the histological degree of malignancy and the degree of tumor cell differentiation evaluated by the staining of glial fibrillary acidic protein (GFAP). In 8 anaplastic astrocytomas and 28 glioblastomas, TN was predominantly immunolocalized in the basement membrane zone of the proliferating tumor vessels; sections of all astrocytomas were negative for TN staining. FN was localized in the basement membrane zone of the vessels in all astrocytomas, 12 anaplastic astrocytomas, and 22 glioblastomas. In 7 anaplastic astrocytomas and 19 glioblastomas, both TN and FN were expressed to various degrees in the tumor vessels. However, most of the TN-positive vessels did not express FN, and most of the FN-positive vessels were negative for TN staining. Furthermore, in 6 anaplastic astrocytomas and 12 glioblastomas, either TN or FN, but not both, were expressed in any area on serial sections. Most of the tumor cells around TN-positive, FN-negative tumor vessels did not express GFAP. On the other hand, GFAP was present in most tumor cells around TN-negative, FN-positive vessels. LN was detected in all vascular and pial-glial basement membrane zone of the tissues examined. These findings indicate that the degree of histological malignancy and the degree of cell dedifferentiation of human gliomas correlate well with the expression of TN, but are inversely correlated with the expression of FN.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1993

Pharmacokinetics of temocapril, an ACE inhibitor with preferential biliary excretion, in patients with impaired liver function.

Six subjects with normal liver function (Group 1) and 7 patients with liver dysfunction (Group 2; mean ICGR15 value 30.5 (5.2)%; range 16 to 56) received a single oral dose of 1 mg temocapril, a prodrug-type ACE inhibitor, with preferentially excreted by the biliary route. The plasma temocapril concentrations in Group 2 at 30 min and 1 h postdose were significantly higher than in Group 1, but the difference had disappeared 2 h postdosing. Although the half life of temocapril diacid in Group 2 was significantly longer than in Group 1, there was no significant difference between the two groups in AUC, Cmax or tmax. In Group 2, urinary recovery of temocapril was significantly increased, suggesting a possible delay in the bioactivation of temocapril into the diacid, but recovery of the diacid itself was not abnormal. ACE inhibitory action in Group 2 remained unchanged. Temocapril is regarded as an ACE inhibitor the disposition and efficacy of which are little affected in patients with impaired liver function.

Adult↗
PubMed1993

Pituitary granuloma and chronic inflammation of hypophysis: clinical and immunohistochemical studies.

We describe five patients with chronic inflammation of the hypophysis including three pituitary granulomas of unknown aetiology. In contrast to the previously reported cases, the involvement of neurohypophysis or hypothalamus was a distinct clinical feature in these patients. Impairment of anterior pituitary function was less prominent, while polyuria and polydipsia occurred in all cases. Enlargement of the sella turcica was absent in three and slight in two cases. CT scan and MR images demonstrated a contrast-enhanced sellar mass in all patients; abnormally thickened pituitary stalk and infundibulum with contrast-enhancement was observed in four. The fibrous tissues were removed by the transsphenoidal approach in four patients, and by the subfrontal approach in one case. In all patients, the endocrinological dysfunction was prolonged. No increase in the size of the remaining pituitary mass was demonstrated on repeated MR images in any of the patients. On histological examination, granulomatous formation was present in three samples, and multinucleated Langhans' giant cells were seen in one. The epithelioid cells and multinucleated giant cells constituting the granulomas were positive for anti-macrophage antibody. No firm laboratory or histological evidence was obtained supporting the presence of systemic disease leading to granulomas. In the other two cases, the pituitary lesions were composed of chronic inflammation tissue, and serum antipituitary antibodies were present in a patient with concurrent Hashimoto's thyroiditis. Our experiences with chronic inflammation of the hypophysis indicate that these patients are best managed by histological confirmation of the lesion followed by adequate hormonal replacement.(ABSTRACT TRUNCATED AT 250 WORDS)

Corticosterone↗
PubMed1993

Effect of Pinellia ternata tuber on the efferent activity of the gastric vagus nerve in the rat.

Effect of intraduodenal infusion with the hot aqueous extract of Pinellia ternata tuber on the efferent discharges in the gastric branch of the vagus nerve was observed in the anesthetized rat. The infusion of the extract in doses of 2-15O mg per animal (c.a. 300 g, b.wt.) resulted in a dose-related increase in efferent activity of the vagal gastric nerve. The enhancement of the nerve activity following administration of 150 mg of this substance lasted longer than 90 min. It was observed that the suppressive effect on vagal gastric activity due to apomorphine and copper sulfate was antagonized by prior administration of the extract. From these observations it is suggested that Pinellia tuber acts as a facilitatory agent on gastric function.

Animals↗
PubMed1993

Identification of human T cell hybridoma-derived macrophage activating factor as interleukin-2.

Macrophages are activated by a two-step mechanism involving at least two kinds of factors, a priming and a triggering factor, to become cytotoxic to various tumor cells. In the present study, we purified macrophage-activating factor for cytotoxicity I (MAF-C I), defined as a priming macrophage activating factor (MAF), by about 1,600-fold from the culture supernatant of a human T cell hybridoma, H3-E9-6, by a series of chromatographic procedures. We identified MAF-C I activity released from H3-E9-6 cells as interleukin-2 (IL-2) from the following findings. (i) The physicochemical properties of MAF-C I and IL-2 were almost identical. (ii) Purified MAF-C I active fraction also showed T cell proliferating activity. (iii) MAF-C I activity in the purified fraction was completely neutralized by anti-IL-2 antibodies. (iv) Human recombinant IL-2 (rIL-2), at a suboptimal dose, and lipopolysaccharide (LPS) synergistically induced monocyte-mediated cytotoxicity.

Cytotoxicity, Immunologic↗
PubMed1993

Identification of two distinct NADH oxidases corresponding to H2O2-forming oxidase and H2O-forming oxidase induced in Streptococcus mutans.

Two distinct NADH oxidases, corresponding to H2O2-forming and H2O-forming enzymes were purified to homogeneity from Streptococcus mutans and their basic properties determined. The H2O2-forming enzyme was a tetramer with a subunit molecular mass of about 56 kDa and required flavin adenine dinucleotide (FAD) for full activity. The enzyme had an isoelectric point of 6.6 and exhibited optimal activity at pH 6.0. The H2O-forming enzyme was a monomer with a molecular mass of 50 kDa and activity independent of exogenously added flavin. The enzyme had an isoelectric point of 4.8 and exhibited optimal activity between pH 7.0 and 7.5. Both enzymes oxidized NADH (Km 0.05 and 0.025 mM for the H2O2- and H2O-forming enzyme, respectively) but not NADPH and contained 1 mol of FAD per monomer. Spectra of the oxidized enzymes exhibited maxima at 271, 383 and 449 nm for the H2O2-forming enzyme and 271, 375 and 447 nm for the H2O-forming enzyme. Antibodies raised against the H2O2-forming enzyme or the H2O-forming enzyme reacted with their corresponding antigen, but did not cross-react. The amino-terminal regions of the two enzymes had completely different amino acid sequences.

Amino Acid Sequence↗
PubMed1993

Pharmacological actions of "kyushin," a drug containing toad venom(2): effects on urinary volume and electrolyte excretion.

A study was conducted on the pharmacological actions of the toad venom-containing drug "Kyushin" (KY-2 and KY-R) on urinary volume and electrolytes excretion, regional blood flow, renal artery blood flow and carrageenin-induced hind-paw edema. In rabbits, KY-2 and KY-R significantly increased urinary volume after intravenous administration of 8 mg/kg. In guinea pigs, KY-2 and KY-R produced a significant increase in urinary volume after intraduodenal administration (i.d.) of 80 mg/kg. In guinea pigs treated with propranolol, KY-2 at 20 and 40 mg/kg p.o. and KY-R at 40 mg/kg p.o. increased urinary volume. At 40 mg/kg i.d. both KY-2 and KY-R produced an increase in regional blood flow, as determined by the hydrogen gas clearance method, of the brain areas including the amygdaloid nucleus, but did not affect regional blood flow in liver, kidney and skeletal muscle, or renal artery blood flow. In rats, carrageenin-induced hind-paw edema was inhibited by KY-2 or KY-R at 600 mg/kg p.o.

Animals↗
PubMed1993

Pharmacological actions of "kyushin," a drug containing toad venom (3): Effects on experimentally induced arrhythmia.

The pharmacological effects of the toad venom-containing drug "kyushin" on aconitine- and thyroxine-induced arrhythmia in guinea pigs, on the conduction system in Langendorff preparations of rabbit hearts and on the autonomic nervous system in cats were studied. "kyushin" significantly inhibited the aconitine-induced arrhythmia after intraduodenal administration (i.d.) with 80 mg/kg, and the thyroxine-induced arrhythmia with 40 mg/kg i.d. Although "kyushin" itself did not affect the conduction system with 30 mg/ml of the maximal concentration being able to be prepared, bufalin and cinobufagin as constituents of toad venom produced inhibition with 0.3 mg/ml and 1 mg/ml, respectively. The decrease in heart rate induced by electrical stimulation to the parasympathetic nerve (vagus nerve) was potentiated by "kyushin" at 30 mg/kg i.d. The anti-arrhythmic effects of "kyushin" may be attributable to both possible inhibitory effect on the conduction system and potentiating effect on the parasympathetic nervous system.

Aconitine↗