Biomedical subjects

K Hashimoto

Publications and source records attributed to K Hashimoto.

At least 811 records · Page 45Linked to original sources

PubMed1996

Characterization of Magnesium Sulfate as an Antiarrhythmic Agent.

BACKGROUND: Recently, intravenous magnesium therapy has been used for the treatment of ventricular arrhythmias, but data to establish a causal link between the electrophysiological properties and the antiarrhythmic actions are lacking. METHODS AND RESULTS: The acute antiarrhythmic effect of magnesium sulfate was assessed using epinephrine-, digitalis-, and coronary ligation-induced canine ventricular arrhythmia models. The intravenous administration of magnesium sulfate (100 mg/kg) reduced the incidence of the ventricular arrhythmias of all models. The antiarrhythmic effect on the epinephrine-induced arrhythmia was potent and long-lasting, while those on the other arrhythmia models were weak and transient. The direct cardiovascular effects were assessed using the canine isolated, blood-perfused sinus node, papillary muscle, and atrioventricular node preparations. The intracoronary administration of magnesium sulfate (0.1-30 mg) suppressed sinoatrial automaticity and ventricular contraction, while it increased atrio-His and His-ventricular conduction time, coronary blood flow, and the duration of monophasic action potential in a dose-dependent manner. The effects on His-ventricular conduction and monophasic action potential duration were less potent compared with the other cardiovascular effects. CONCLUSIONS: These results suggest that magnesium sulfate possesses multiple electrophysiological properties and that the effects related to the calcium channel inhibition may be the most relevant for the antiarrhythmic actions.

Journal Article↗

PubMed1996

Expression of oxytocin receptor in human pregnant myometrium.

Around the onset of labor, uterine sensitivity to oxytocin (OT) increases tremendously. Although this is considered to reflect OT receptor (OTR) augmentation in myometrium, neither spatial expression of OTR nor the level of the receptor message during the course of pregnancy have been investigated at the molecular level. We examined the localization and expression of the OTR in human myometrium by means of in situ hybridization, immunohistochemistry, and Northern and Western blotting. In the term pregnant myometrium, OTR expressing smooth muscle cells are observed diffusely and heterogeneously. Some of the smooth muscle cells were expressed high levels of the receptor at the messenger RNA and protein level, and they were surrounded with cells weakly positive for the OTR or negative. The level of OTR transcripts increased according to the course of pregnancy. The receptor messenger RNA level reached over 300-fold at parturition compared with the nonpregnant myometrium. In the myometrium at 32 weeks of gestation and not in labor, a relatively large amount (about 100-fold) of the receptor message was expressed. In the nonpregnant myometrium, significant amount of the receptor protein was revealed by Western blotting. We also found that the receptor protein was augmented at term and after the onset of labor. These findings indicated that the expression of OTR changes dynamically at the transcription and protein level during pregnancy and that its expression is heterogeneous in the term myometrium.

Amino Acid Sequence↗

PubMed1996

Molecular cloning and expression of human liver biliverdin-IX beta reductase.

The cDNA encoding for human liver isozyme I of biliverdin-IX beta reductase was cloned from human liver cDNA libraries. The constructed cDNA of 853 bp in length contained an entire reading frame coding 206 amino acid residues. It was found that isozyme 1 of biliverdin-IX beta reductase is identical to human erythrocyte NADPH-flavin reductase recently reported in a communication by Chikuba et al., Biochem. Biophys. Res. Commun., 198, 1170-1176 (1994). We, further, characterized this mRNA by Northern blot analyses of poly(A) RNA from four different human fetal tissues and eight different human adult tissues showed hybridization mainly to liver RNA in fetal tissues and to skeletal muscle and liver RNA in adult tissues. Southern blot analysis indicated that isozyme I of biliverdin-IX beta reductase appeared to be a single copy gene. Insertion of the enzyme-coding sequence into an expression vector pET-3c yielded relatively high amounts of the active enzyme in E. coli. The amino terminal sequence of the recombinant protein was identical to that of native enzyme, indicating that E. coli also removed the N-terminal methionine to produce the mature form. The recombinant and native biliverdin-IX beta reductases were indistinguishable as far as their mobility on SDS-PAGE gel, immunoreactivity and specific activity were concerned.

Amino Acid Sequence↗

PubMed1996

Acceleration of glycolysis in erythrocytes by the antidiabetic agent M16209.

The effects of M16209 (1-(3-bromobenzofuran-2-ylsulfonyl)hydantoin), an antidiabetic agent and aldose reductase inhibitor, on glycolysis were studied in rat and human erythrocytes in vitro. M16209 increased lactate production from glucose when incubated with rat and human erythrocytes, and also increased glucose consumption in rat erythrocytes. The rates of production of lactate in rat erythrocytes treated with M16209 at 10, 25 and 50 microM were 113, 118 and 123%, respectively, of those in vehicle treated cells. Sorbinil (aldose reductase inhibitor), tolbutamide (sulfonylurea), and buformine (biguanide) did not increase lactate production in rat erythrocytes when tested at 50 microM. On the other hand, M16209 did not affect lactate production from D-glyceraldehyde in rat erythrocytes. At 100 microM the agent decreased both glucose-6-phosphate and fructose-6-phosphate in rat erythrocytes, and increased fructose-1,6-bisphosphate; at 10 microM it also increased 6-phosphofructokinase activity in rat hemolysates. These findings suggest that M16209 accelerates glycolysis in erythrocytes via activation of 6-phosphofructokinase.

Aldehyde Reductase↗

PubMed1996

Antiarrhythmic and proarrhythmic effects of sematilide in canine ventricular arrhythmia models.

Using canine ventricular arrhythmia models induced by two-stage coronary ligation, digitalis, adrenaline, coronary ligation and reperfusion, and programmed electrical stimulation (PES), we examined the antiarrhythmic or proarrhythmic effects of sematilide, N-[2(diethylamino)ethyl]-4-[(methylsulfonyl)amino]-benzamide hydrochloride. Sematilide in an intravenous (i.v.) dose range of 0.3 to 6.0 mg/kg prolonged the QTc interval, but had an antiarrhythmic effect only on the arrhythmias induced by PES (7 out of 10 dogs with old myocardial infarction). Sematilide was not effective on coronary ligation and reperfusion arrhythmia or the spontaneously occurring automaticity arrhythmias induced by two-stage coronary ligation, digitalis and adrenaline, respectively, and even aggravated digitalis- and adrenaline-induced arrhythmias. These results indicate that the class III agent sematilide is similar to other new class III agents, such as d-sotalol, E-4031 and MS-551, in that it was not effective on the automaticity arrhythmias, but different from these new class III agents, in that sematilide prevented only the induction of ventricular arrhythmias induced by PES and did not suppress the coronary ligation-reperfusion arrhythmias. The PES induced arrhythmias are thought to be induced exclusively by a reentrant mechanism, but the reperfusion arrhythmias may involve not only re-entry, but also automaticity, and we reported the effectiveness of MS-551, E-4031 and d-sotalol on the latter arrhythmia. Sematilide is different in that it even aggravated some automaticity arrhythmias.

Animals↗

PubMed1996

Inhibitory effect of arphamenine A on intestinal dipeptide transport.

Arphamenine A, an Arg-Phe analog without a peptide bond, has been reported to be a possible inhibitor of the peptide transporter [H. Daniel and S.A. Adibi, FASEB J., 8, 753 (1994)]. The present study demonstrated that arphamenine A is not a real inhibitor, but is a substrate for the transporter, being transported transepithelially under a proton gradient. The substrate specificity of the peptide transporter was wider than expected.

Biological Transport, Active↗

PubMed1996

Hypothalamic-pituitary-adrenal axis in WBN/Kob rats with non-insulin dependent diabetes mellitus.

In an attempt to define the hypothalamic-pituitary-adrenal (HPA) axis in non-insulin dependent diabetic rats (WBN/Kob), we measured plasma corticotropin releasing factor (CRF), as well as arginine vasopressin (AVP), ACTH, and corticosterone (B), CRF concentrations in the median eminence (ME), the remainder of the hypothalamus (rHY) and the neurointermediate lobe of the pituitary (NIL). We also measured Iodine-125-labeled ovine CRF ([125I]oCRF) binding in the brain and peripheral tissues. Body and thymus weight in WBN/Kob rats were significantly lower than in control Wistar rats, but adrenal weight was higher in WBN/Kob rats. Plasma ACTH levels were significantly higher in WBN/Kob rats than in the control rats. However, plasma CRF, AVP and B levels in WBN/Kob rats were not different from those in the control rats. The CRF concentration was significantly decreased in the ME of the diabetic rats, compared with control rats, but CRF concentrations in the rHY and NIL were unchanged in the two groups. A significant reduction in [125I]oCRF binding in the anterior pituitary was demonstrated in WBN/Kob rats, but no significant difference between the diabetic and control rats in CRF binding was observed in the frontal cortex, spleen or adrenal gland. These findings suggest that the HPA axis is chronically stimulated in the non-insulin dependent diabetic rats.

Adrenal Glands↗

PubMed1996

Differential changes of corticotropin releasing hormone (CRH) concentrations in plasma and synovial fluids of patients with rheumatoid arthritis (RA).

Corticotropin releasing hormone (CRH) and ACTH concentrations in plasma and CRH and IL-6 concentrations in synovial fluid in patients with rheumatoid arthritis (RA) were examined to clarify the relationship between cytokines and the hypothalamic-pituitary-adrenal axis (HPA axis). Concentrations of serum amyloid A protein (SAA), one of the acute phase proteins, were also measured as an indicator of inflammation. CRH and IL-6 concentrations in synovial fluid were higher in RA patients than in control patients (osteoarthritis, OA). Plasma ACTH and CRH levels were significantly lower in RA patients than in OA patients. This suggests that CRH secretion in synovial fluid is regulated differently from plasma CRH secretion, as CRH levels in synovial fluid and plasma showed opposite changes in RA patients. SAA levels were positively correlated with the levels of CRH or IL-6 in synovial fluid, whereas there was no correlation between CRH and IL-6 levels. The results suggest that CRH and IL-6 play important independent roles in producing SAA in synovial fluid.

Adrenocorticotropic Hormone↗

PubMed1996

Changes in oxytocin receptor mRNA in the rat uterus measured by competitive reverse transcription-polymerase chain reaction.

Large changes in the responsiveness of target organs to oxytocin are thought to originate from alteration of the number of oxytocin receptors (OTR). To elucidate the molecular mechanisms regulating the synthesis of the OTR, we developed a competitive reverse transcription-PCR protocol to measure OTR mRNA. We synthesized cRNA comprising a small stuffer introduced into the target mRNA. Using this cRNA as an internal standard, we made a quantitative estimation of OTR mRNA. Application of this method to the rat uterus revealed that the mean levels of OTR mRNA remained unchanged until 1030-1100 h on day 21 of pregnancy, increased significantly after 2200-2230 h on the same day and declined rapidly after parturition. A similar rapid increase in uterine OTR mRNA content was observed in rats given prostaglandin on day 18, inducing premature delivery on day 19 of pregnancy. All parturient rats had higher OTR mRNA levels regardless of whether parturition was spontaneous or prostaglandin induced. However, in a few rats, OTR mRNA remained as low as that observed during mid pregnancy even on day 22 of gestation, the expected day of parturition in about 70% of the rats in our colony. A similar increase in uterine OTR mRNA content to that observed at parturition was induced by oestrogen treatment for 3 days in ovariectomized virgin rats, but concomitant injection of progesterone did not influence the effect of oestrogen. The present results revealed that the large increase of uterine OTR at the peripartum period is accompanied by an increase in OTR mRNA content that may be brought about, at least in part, by increased oestrogen secretion following luteolysis.

Animals↗

PubMed1996

Positivity for antinuclear antibody in patients with advanced rheumatoid arthritis.

Some patients with rheumatoid arthritis (RA) as well as those with other collagen diseases are positive for antinuclear antibody (ANA). We investigated the frequency of positivity for ANA in 104 patients with RA and evaluated the clinical features and laboratory data in the ANA-positive and -negative groups. The presence of ANA in sera was studied by indirect immunofluorescence using HEp-2 cells as the antigen substrate. Sera with a positive fluorescence at a dilution of 1:20 were considered to be positive for ANA. Of the 104 patients, 39 (37.5%) were positive for ANA. The staining pattern in the positive cases varied, but most were speckled (64.1%) and homogeneous (48.7%). A small number showed a nucleolar (20.5%) or a centromere (10.3%) pattern. None showed a shaggy pattern. The ANA titer was lower in RA patients compared with those with other collagen-related diseases such as systemic lupus erythematosus or progressive systematic sclerosis. None of the patients positive for ANA with either a nucleolar or centromere staining pattern had progressive systemic sclerosis or the CREST syndrome. One patient each had Raynaud's phenomenon and pulmonary fibrosis. There was no correlation between ANA positivity and indicators of joint inflammation. The prevalence of ANA positivity in patients with advanced or prolonged disease was higher than those with early stages or short durations. There was no correlation with drug therapy.

Adult↗

PubMed1996

Secretion of anterior pituitary hormones in patients with insulin-dependent diabetes mellitus and polyglandular autoimmune syndrome.

We extracted gammaglobulins from the serum of 10 patients with insulin-dependent diabetes mellitus (IDDM) to investigate their effect on anterior pituitary hormone secretion using cultures of rat anterior pituitary cells. Three of the 10 patients also had the polyglandular autoimmune syndrome (PGA) type III with an isolated failure of anterior pituitary hormone secretion. The gammaglobulin from each of the 3 patients with PGA and an isolated failure of secretion of adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH) or gonadotropin inhibited the secretion of ACTH, TSH or gonadotropin in cultures of rat anterior pituitary cells. The gammaglobulins obtained from the other 7 patients with IDDM also showed an inhibitory or stimulatory effect on anterior pituitary hormone secretion in vitro. We postulate that some patients with IDDM, especially those with other endocrine autoimmune diseases, may have substances in their gammaglobulin fraction that can affect the secretion of anterior pituitary hormones.

Adrenocorticotropic Hormone↗

PubMed1996

Simple obesity with cardiomyopathy of obesity.

A 32-year-old obese female was hospitalized with dyspnea. Echocardiogram revealed left ventricular dilatation. Chest X-ray film showed enlarged heart size and prominent pulmonary congestion. Simple obesity with congestive heart failure (CHF) due to cardiomyopathy of obesity was diagnosed according to the absence of obvious disease that caused obesity or CHF. After diet therapy and medication, subjective symptoms disappeared and body weight was reduced from 137 kg to 85 kg. Although few reports of cardiomyopathy of obesity have been reported in Japan, we propose the possibility that similar cases will be on the increase because Japanese dietary habits are now becoming more similar to those of Caucasians.

Adult↗

PubMed1996

[Onset of dyspnea on exertion in elderly and young patients with congestive heart failure].

We previously reported that dyspnea on exertion in patients with congestive heart failure was not associated with pulmonary function ar rest, but was associated with the appearance of the anaerobic threshold and with the respiratory compensation point during exercise. Here we described a study of the influence of aging on the onset of dyspnea on exertion in elderly and in young patients with congestive heart failure. A total of 53 patients were studied: 35 were less than 65-year-old (average age, 47-year-old; 19 men and 16 women) and 18 were more than 65-year-old (average age, 70-year-old; 13 men and 5 women). All patients underwent maximal graded exercise testing on a bicycle ergometer. The workload increased according to a ramp protocol, and perceived exertion was evaluated with the Borg scale. The anaerobic threshold, the respiratory compensation point, and the peak VO2 were recorded. Values of 13 (somewhat hard) and 17 (very hard) on the Borg scale were considered to mark the start of dyspnea on exertion and an increase in dyspnea on exertion respectively. In the young patients, dyspnea on exertion began at about the time that the anaerobic threshold was reached, and it increased at about the time that the respiratory compensation point was reached. In contrast, elderly patients dyspnea on exertion began 70 seconds after the anaerobic threshold was reached, and it increased 30 seconds after the respiratory compensation point was reached. The VO2 at the start of dyspnea on exertion and the VO2 at the anaerobic threshold correlated more closely in the young patients than in the old patients. The same was true of the VO2 at the time that dyspnea on exertion increased and the VO2 at the respiratory compensation point. These findings suggest that elderly patients with congestive heart failure are less sensitive to the stimuli that cause dyspnea than are young patients.

Adolescent↗

PubMed1996

Primary intramedullary spinal cord germinoma. Case report.

Primary central nervous system germinoma usually presents as an extraaxial intracerebral mass. The authors report the rare occurrence of an intramedullary spinal cord germinoma at the conus medullaris in a 24-year-old man, which was treated by partial removal and radiation therapy. The tumor was highly radiosensitive and the patient remains disease free 15 months posttreatment.

Adult↗

PubMed1996

A novel nonsense mutation in exon 1 and a transition in intron 3 of the lipoprotein lipase gene.

We examined the lipoprotein lipase (LPL) gene by single strand conformation polymorphism (SSCP) and by restriction fragment length polymorphism (RFLP) analysis in 106 patients with hypertriglyceridemia to screen for novel mutations and to study the contribution of LPL genetic defects in hypertriglyceridemia. We found a single incidence of a homozygous novel nonsense mutation (216G-->A; -14Tryptophan-->stop codon) in exon 1 and 6 cases heterozygous for a single transition (C-->T) at six bp upstream from splicing acceptor site of intron 3. These mutations were not found in 105 normolipidemic controls. The proband homozygous for the nonsense mutation in exon 1, a 74 year old woman, had mild hyperchylomicronemia and her post-heparin plasma showed no LPL protein. However, four heterozygous among family members did not demonstrate hypertriglyceridemia. The frequency of heterozygosity for the C-->T transition in intron 3 was significantly different from that in normolipidemic controls. Therefore, it was suggested that the mutation is involved in hypertriglyceridemia. All of the heterozygotes were men with 4 patients having impaired glucose tolerance or diabetes mellitus. These observations suggest that this polymorphism in intron 3 combined with other as yet undefined factors may be related to hypertriglyceridemia.

Adult↗

PubMed1996

Transforming and differentiation-inducing potential of constitutively activated c-kit mutant genes in the IC-2 murine interleukin-3-dependent mast cell line.

Two mutations of c-kit receptor tyrosine kinase (KIT), valine-559 to glycine (G559) and aspartic acid-814 to valine (V814), resulted in its constitutive activation. To examine the transforming and differentiation-inducing potential of the mutant KIT, we used the murine interleukin-3-dependent IC-2 mast cell line as a transfectant. The IC-2 cells contained few basophilic granules and did not express KIT on the surface. The KITG559 or KITV814 gene was introduced into IC-2 cells using a retroviral vector. KITG559 and KITV814 expressed in IC-2 cells were constitutively phosphorylated on tyrosine and demonstrated kinase activity in the absence of stem cell factor, which is a ligand for KIT. IC-2 cells expressing either KITG559 or KITV814 (IC-2G559 or IC-2V814 cells) showed factor-independent growth in suspension culture and produced tumors in nude athymic mice. In addition, IC-2G559 and IC-2V814 cells showed a more mature phenotype compared with the phenotype of the original IC-2 cells, especially after transplantation into nude mice. The number of basophilic granules and the content of histamine increased remarkably. KITG559 and KITV814 also influenced the transcriptional phenotype of mouse mast cell proteases (MMCP) in IC-2 cells. The expression of MMCP-2, MMCP-4, and MMCP-6 was much greater in IC-2G559 and IC-2V814 cells than in the original IC-2 cells. The results indicated that constitutively activated KIT had not only oncogenic activity but also differentiation-inducing activity in mast cells.

Animals↗

PubMed1996

The Chinese herbal remedy, T2, inhibits mitogen-induced cytokine gene transcription by T cells, but not initial signal transduction.

T2, an extract of Tripterygium wilfordii Hook F, has been reported to be effective in the treatment of a variety of autoimmune diseases, including rheumatoid arthritis. Previous studies have shown that T2 inhibited mitogen- or antigen-induced proliferation of human peripheral blood T cells and B cells, IL-2 production by T cells and Ig production by B cells. In contrast, T2 did not affect monocyte functions, such as IL-1 production and antigen presentation. The current studies sought to localize the immunosuppressive action of T2 more precisely. Results show that T2 prevented [3H]-uridine uptake by mitogen-stimulated T cells and arrested them in the early GI phase of the cell cycle. The inhibitory effects of T2 could be partially overcome by costimulating PHA activated T cells with PMA and completely nullified by costimulation with PMA plus a monoclonal antibody to CD28. Moreover, T2 had no effect on expression of IL-2R or the transferrin receptor (CD71), but inhibited production of a number of cytokines, including IL-2 and IFN-gamma by activated T cells. T2 suppressed IL-2 mRNA levels, but not IL-2R mRNA levels, in activated T cells. T2-mediated inhibition reflected suppression of IL-2 gene transcription as indicated by suppression of the expression of a reporter gene driven by the IL-2 promoter. T2 had little inhibitory effect on either IL-2 gene expression or cell cycle progression when added after initial mitogenic stimulation, indicating that an early step in the cascade of activation events was inhibited. However, initial activation events including protein tyrosine phosphorylation, the generation of diacylglycerol, IP3, and the translocation of protein kinase C were not inhibited by T2. Moreover, T2 did not inhibit the phosphatase activity of calcineurin. These results have localized the effect of T2 to a step in the T cell activation cascade after initial second messenger generation, tyrosine phosphorylation and protein kinase activation, but before IL-2 gene transcription.

Adult↗

PubMed1996

[Changes of neopterin in cerebrospinal fluid and serum in children with meningitis].

Neopterin is synthesized mainly by monocytes/macrophages and is considered to be a marker for activation of the cellular immune system. In patients with bacterial or aseptic meningitis, elevated neopterin levels in cerebrospinal fluid (CSF) have been demonstrated. We studied the time courses of CSF and serum neopterin in children with meningitis. The CSF neopterin levels on admission were significantly higher in patients with bacterial meningitis (82.4 +/- 37.0 nmol/L) than in those with aseptic meningitis (32.3 +/- 22.1 nmol/L) or in those with non-pleocytotic CSF (6.9 +/- 4.4 nmol/L). The CSF neopterin levels in the patients with bacterial meningitis were remarkably increased (234.5 +/- 100.2 nmol/L) one day after admission, but the serum neopterin levels were not increased. There was no correlation between CSF neopterin levels and CSF cell count or CSF protein, nor between serum neopterin levels and serum C-reactive protein or peripheral leukocyte count. But the CSF neopterin levels one day after admission were related to the period of positive serum C-reactive protein. CSF neopterin levels in patients with bacterial meningitis were increased one day after admission. The levels in two patients with high levels of CSF IFN-gamma and TNF-alpha were remarkably increased. All patients with bacterial meningitis had received treatment with antibiotics and dexamethasone. It has been reported that TNF-alpha enhances the effect of IFN-gamma for neopterin release by macrophages in vitro and that dexamethasone has the same effect on IFN-gamma as TNF-alpha. The present study suggests that elevation of CSF neopterin in bacterial meningitis results from monocytes/macrophages costimulated with IFN-gamma, TNF-alpha and dexamethasone used in treatment.

Adolescent↗