Biomedical subjects

Y Hirota

Publications and source records attributed to Y Hirota.

At least 55 records · Page 3Linked to original sources

PubMed1999

Distinct roles of peroxynitrite and hydroxyl radical in triggering stunned myocardium-like impairment of cardiac myocytes in vitro.

Myocardial stunning is characterized by the impairment of excitation-contraction coupling via a decrease in myofilament Ca2+ responsiveness, thought to be triggered by hydroxyl radicals (*OH) generated upon reperfusion. Since peroxynitrite is also expected to be produced during reperfusion, we examined whether it can induce a stunned myocardium-like impairment of cardiac myocytes. Its effect on cultured cardiac myocytes was compared with that of hydrogen peroxide (H2O2), *OH source. Infusion of peroxynitrite (0.2 mM) induced a decrease in cell motion and a complete arrest in diastole at 2.9 +/- 0.3 min, which coincided with an elevation in [Ca2+]i. Arrest induced by infusion of H2O2 (10 mM) was not associated with an increase in [Ca2+]i. The ATP content was unaffected by peroxynitrite (control, 34.3 +/- 3.4: + peroxynitrite, 32.9 +/- 3.5 nmol/mg protein) and the cells remained viable. Sulfhydryl (SH) content was decreased by peroxynitrite, but not by H2O2. The membrane fluidity (a measure of peroxidation of the membrane lipids) was not affected by peroxynitrite, but was decreased by H2O2. Onset time of arrest was unaffected by deferoxamine (0.2 mM), but was delayed by DTT (10 mM) (from 2.9 +/- 0.3 to 19.2 +/- 1.6 min). Nitrotyrosine content was unchanged by peroxynitrite, and its augmentation with Fe3+/EDTA (1 mM) was not associated with a shortened onset time of arrest. The function of the Na+/Ca2+ exchanger was impaired by peroxynitrite, but not by H2O2. Peroxynitrite and H2O2 each induce arrest, but only the former increases [Ca2+]i. One of the mechanisms of the increase in [Ca2+]i is Na/Ca2+ exchanger dysfunction. The impairments were induced through SH oxidation by peroxynitrite, but through lipid peroxidation by H2O2. Myocardial stunning may be induced by both species in concert.

Adenosine Triphosphate↗

PubMed1999

Osteoporosis and years since menopause.

In Fukuoka Prefecture, in south-western Japan, a regional screening program for osteoporosis was conducted from 1994 to 1995. The screening level in the bone mineral density (BMD) at the distal non-dominant radius was equal to or less than two standard deviations below age-specific mean (< or = -2.0 SD). In 1177 examinees with natural menopause (mean age: 61.4, range: 42-88), 56 of those who were screened were subsequently radiologically confirmed by orthopedic specialists to have osteoporosis (case group). They were then compared with 802 normal BMD (> or =-1.0 SD) women (reference group) with their lifestyle and reproductive characteristics. The adjusted odds ratio (OR) and its 95% confidence interval (CI) were calculated using a logistic regression model. A significant increase in the ORs for osteoporosis based on the number of years since menopause was observed for 7-13 years since menopause (OR = 2.3; 95% CI: 1.0-5.4) compared with <7 years, however, no increasing trend in risk was evident in 14+ years since menopause (OR = 1.4; 95% CI: 0.4-5.1). Thus, the elevated risk continued up to around 10 years since menopause. These findings are consistent with previous studies that reported an alternation in the calcium metabolism and bone loss related to the length of time after menopause. Both the childhood and current milk consumption were also associated with a decreased risk: ORs were 0.4 (95% CI: 0.2-0.9) and 0.5 (95% CI: 0.3-1.0), respectively.

Confidence Intervals↗

PubMed1999

Hematopoietic stem cell transplantation (HSCT) for Langerhans cell histiocytosis (LCH) in Japan.

There exists limited information about the usefulness of hemopoietic stem cell transplantation (HSCT) for the treatment of patients with refractory Langerhans cell histiocytosis (LCH). We report here four Japanese pediatric patients with multisystem LCH disease who underwent HSCT between 1994 and 1997. Two of the four patients are doing well without any relapse. However, neither of them shows improved sequelae 3 to 4 years after allogeneic HSCT, although the graft was rejected in one of the cases. The remaining two patients died of septic shock. A review of the literature of 11 patients revealed four fatalities after the use of HSCT in the treatment of LCH. Three of these were due to active LCH and three deaths occurred within 2 months after HSCT. To establish the usefulness of HSCT for refractory LCH, further studies are required.

Child↗

PubMed1999

Visualization of biphasic Ca2+ diffusion from cytosol to nucleus in contracting adult rat cardiac myocytes with an ultra-fast confocal imaging system.

In contracting cardiac myocytes, the rapid changes in cytosolic and nuclear Ca2+ make it difficult to determine whether the nuclear Ca2+ transient is caused by diffusion from the cytosol or by Ca2+ release channels on the inner nuclear membrane, or both. The propagation mechanism in the nucleoplasm also remains unknown. We have developed an ultra-fast Nipkow confocal imaging system able to acquire two-dimensional images at approximately 4 ms/full frame speed and employed it to analyze Ca2+ waves and the dynamics of the cytosolic and nuclear Ca2+ transients after electrical stimulation of cardiac myocytes. The pattern of nuclear Ca2+ upon stimulation was well described by a mathematical model of Ca2+ diffusion across the nuclear envelope. No evidence of Ca2+ release from perinuclear Ca2+ stores was obtained. The Ca2+ diffusion constant appeared to change during contraction, with essentially free diffusion of Ca2+ through nuclear pore complexes at low cytosolic Ca2+ and partially restricted diffusion at high cytosolic Ca2+. The Ca2+ in the nucleoplasm propagated by diffusion and no Ca2+ release phenomena were seen in the nucleus.

Animals↗

PubMed1999

Ulcerative colitis and colorectal cancer: a follow-up study in Fukuoka, Japan.

BACKGROUND: Our goal was to study the higher death rate and the causes of such deaths among ulcerative colitis (UC) patients in the Japanese population, and to compare our findings in such cases with those for Crohn's disease (CD). METHODS: In all, 174 UC (male/female: 54/120) and 66 CD (34/32) patients who were registered for the research promotion programme in Fukuoka prefecture (1971-1981) were traced up to the end of 1994. The standardized mortality ratios (SMR) were calculated based on the death rates of the Japanese population by age, sex and calendar year. RESULTS: The overall follow-up rate was 96.7%. Among the UC patients, the SMR for all causes were 0.84 (95% CI: 0.11-4.31) for men; 1.05 (95% CI: 0.08-4.69) for women; and 0.94 (95% CI :0.09-4.50) for both sexes combined. When excluding deaths due to colorectal cancer, the SMR for the same groups were 0.43, 0.94 and 0.67, respectively. The SMR for both sexes were 1.82 (95% CI: 0.17-5.96) for malignant neoplasms and 9.93 (95% CI: 4.67-17.3) for colorectal cancer. Patients who died from colorectal cancer showed onset at a younger age (mean: 25.5 years) as well as a longer disease course of UC (mean: 17.0 years). Regarding the CD patients, the SMR for all causes were 1.75 (95% CI: 0.15-5.75) for both sexes. Most deaths were caused by gastrointestinal complications. CONCLUSIONS: An excess mortality from colorectal cancers was indicated in the UC patients, especially in males. The overall SMR in male UC patients decreased by 50% when the deaths from colorectal cancer were excluded. The excess mortality in those with CD over UC patients was attributed to gastrointestinal complications rather than malignant diseases. Some carcinogenic factors therefore seem most likely to exist in the pathogenesis of UC.

Adolescent↗

PubMed1999

A possible function of DNA curvature in a vector system that allows efficient expression of heterologous proteins in CHO cells.

A cis-acting element derived from the nontranscribed spacer region of murine rDNA allows efficient expression of heterologous proteins in transformed Chinese hamster ovary (CHO) cells. Analysis of the structural conformation of this cis-acting element revealed that it has a DNA curvature. Whether the DNA curvature plays any roles in regulating expression of heterologous proteins or not has been studied.

Animals↗

PubMed1999

Impaired sarcoplasmic reticulum function in lipopolysaccharide-induced myocardial dysfunction demonstrated in whole heart.

To clarify the pathophysiological cascade leading to lipopolysaccharide- (LPS) induced myocardial dysfunction, we measured sarcoplasmic reticulum (SR) function, expression of inducible nitric oxide synthase (iNOS), and left ventricular (LV) function in a rat whole heart model. The LV function was evaluated by peak LV pressure and SR function was evaluated by the mechanical restitution (MR) curve, a physiological parameter of SR function. The mechanical restitution curve was constructed by plotting extrasystolic potentiation of LV dP/dt during extrasystoles (100-700 ms) under fixed pacing. Functions were evaluated using the perfusion apparatus at 6 or 24 h after LPS administration. In the 6 h group, LV pressure was depressed to 62% of the control, the SR function was impaired, and iNOS protein was expressed. In the 24 h group LV pressure and SR function remained at the control levels, iNOS was not detected. In the 6 h group dexamethasone co-administration normalized the LPS effect and iNOS was not expressed. LPS-induced myocardial dysfunction appeared to be caused by impaired SR function and NO expression suggesting that NO may act as a trigger.

Animals↗

PubMed1999

Apoptosis observed in BALB/3T3 cells having ingested Staphylococcus aureus.

Staphylococcus aureus was previously shown to be internalized by murine fibroblast. We examined the intracellular events of S. aureus ingested by BALB/3T3 cells. After uptake of strains A191 and A151, isolates from atopic lesion, and a laboratory strain, Cowan I, for 1 hr, BALB/3T3 cells were incubated with 1.25 microg/ml lysostaphin. Laddering of the DNA in multiples of approximately 180 bp occurred within 4 hr following bacterial addition in BALB/3T3 cells infected with A191 and within 18 hr in BALB/3T3 cells infected with A151: histochemical staining by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method revealed that the rate of the fragmentation of nucleic DNA in Cowan I-infected BALB/3T3 cells at 21 hr following bacterial addition was 0.52 +/- 0.25%, significantly higher than that in the control cells. Transmission electron micrographs of BALB/3T3 cells at 4 hr following A191 addition showed that the apoptotic features, including electron-dense nucleus and plasma membrane blebbing, occurred in some cells in which many staphylococci escaped the endosome and went on to cell division. At the same time, A151 organisms enclosed with endosome membrane were static in the intact BALB/3T3 cells. The significant increase of A191 was confirmed by counting intracellular live bacteria during 2- to 6-hr incubation. These results suggest that internalized S. aureus escapes the endosome, multiplies and induces apoptosis in the fibroblast cell.

3T3 Cells↗

PubMed1999

[Steroid pulse therapy and vital prognosis among pediatric cancer patients with sepsis].

The usefulness of glucocorticosteroid therapy in patients with sepsis has been controversial. We investigated the effect of steroid pulse therapy on the vital prognosis of pediatric patients with sepsis and followed the vital status up to one month after the use of pulse therapy. We reviewed the medical records of 89 pediatric cancer patients with sepsis treated at our hospital between 1988 and 1996. The risks of potential predictors were estimated by calculating crude and adjusted relative risk (RR). The total cumulative death was 33/89 (25%). All patients treated with steroid pulse therapy died (12/12). Patients with either interstitial pneumonia (IP), infection-associated hemophagocytic syndrome (IAHS) and graft-versus-host disease (GVHD) showed a significantly higher cumulative death (57% (12/21) vs 31% (21/68), p = 0.03). Increased risk of cumulative death was suggested for the older age group, inappropriate antimicrobial therapy, and the conditions requiring steroid pulse therapy (IP, IAHS, and GVHD), (crude RR were 1.6, 1.6, and 1.9, respectively). However, when adjusted for pulse therapy, these three factors no longer indicated risk elevation, (adjusted RR = 1.2, 1.2, and 0.3, respectively). On the other hand, steroid pulse therapy per se was independently associated with increased risk of cumulative death (crude RR = 3.6, adjusted RR = 10). Thus, the risk of the conditions requiring steroid pulse therapy (IP, IAHS, and GVHD) firstly observed could be regarded as an apparent association due to steroid pulse therapy.

Child↗

PubMed1999

Effects of interferons on cortisol production in bovine adrenal fasciculata cells stimulated by adrenocorticotropin.

The effects of interferons (IFNs) IFN-alpha, IFN-beta and IFN-gamma on the production of cortisol in bovine adrenal fasciculata cells have been investigated. Pretreatment of the fasciculata cells with recombinant interferon-alpha-2b from man (over 300 units mL(-1)), but not with fibroblast IFN-beta or recombinant IFN-gamma from man, reduced the production of cortisol in cells stimulated with adrenocorticotropin (ACTH) (1 nM). IFN-alpha-2b inhibited ACTH-induced cortisol production in a concentration- (300-15000 units mL(-1)) and time- (2-24h) dependent manner. The inhibitory effect of IFN-alpha-2b on the production was abolished when the cells were simultaneously treated with anti-IFN-alpha antibody, and it was reversible. IFN-alpha-2b also inhibited dibutyryl cyclic AMP-induced production of cortisol but not pregnenolone-induced production. The effect of IFN-alpha-2b was not influenced by increases in external ACTH and Ca2+ concentrations and IFN-alpha-2b did not affect the ACTH-induced increase in cyclic AMP level in the cells. These results strongly suggest that IFN-alpha-2b reduces ACTH-induced production of cortisol in bovine adrenal fasciculata cells by affecting the early process of cortisol synthesis. The results also indicate that IFNs might not directly affect steroidogenesis in the adrenal cortex in-vivo, because of the requirement of high concentrations of IFN-alpha-2b for inhibition, and because of the ineffectiveness of IFN-beta and IFN-gamma.

Adrenocorticotropic Hormone↗

PubMed1999

Biological activities of 1,1,6-trisubstituted indanes: beyond magainin 2.

MSI-78 is a peptide analog of naturally occurring magainin 2 isolated from the skin of Xenopus laevis. The peptide is known to have one of the strongest antibacterial activities in magainin 2 analogs against methicillin-resistant Staphylococcus aureus (MRSA). To find novel compounds superior to MSI-78, we have further designed, synthesizing 1,1-di(4-aminobutyl)-6-benzylindane (PM4) and 1,1-dibenzyl-6-(4-aminobutyl) indane (PM5), and tested their inhibitory ability of the growth of S. aureus. In an in vitro assay, PM4 showed the same antibacterial activity against the bacterium as MSI-78, and non-hemolytic activity against human red blood cells (RBCs) at the MIC (minimum inhibitory concentration) value, in contrast to the latter. On the other hand, PM5 showed stronger antibacterial activity than MSI-78, but being still accompanied with hemolysis at the MIC value. Otherwise, stronger decarboxylase activity for oxaloacetate was observed in PM5, rather than magainin 2 analogs or Oxaldie 1 as a control peptide, but not in PM4.

Amino Acid Sequence↗

PubMed1999

Prognostic significance of the pattern of multivessel spasm in patients with variant angina.

Multivessel spasm in variant angina is believed to be a major prognostic factor. Three patterns of multivessel spasm have been detected: (1) spasm at different sites on different occasions (migratory spasm); (2) spasm sequentially affecting 2 different sites (sequential spasm); and (3) simultaneous spasm at more than 1 site (simultaneous spasm). The present study investigated the prognosis based on this factor for variant angina without fixed coronary stenosis and examined the influence of multivessel spasm on cardiac events. Twenty-six patients were diagnosed as having variant angina without fixed coronary stenosis using 12-lead 24-h ECG recording system and coronary cineangiography. These patients were followed up prospectively for 57.1+/-7.6 months. Of the 26 patients 13 had single-vessel spasm, 6 had migratory multivessel spasm angina, and 7 showed sequential and/or simultaneous multivessel spasm angina. The survival free of serious cardiac events and of all cardiac events was significantly lower for patients with sequential and/or simultaneous multivessel spasm than for those with migratory multivessel spasm (p<0.05, p<0.05), whereas for patients with migratory multivessel spasm the difference comparison with single-vessel spasm did not attain statistical significance (p = ns, p = ns). The results of this study suggest that there seems to be a high-risk subgroup (i.e., sequential and/or simultaneous multivessel spasm) among patients with variant angina.

Aged↗

PubMed1999

Dual-chamber pacing in hypertrophic obstructive cardiomyopathy: a comparison of acute and chronic effects.

This study describes the acute and chronic effects of dual-chamber (DDD) pacing in 14 consecutive patients with hypertrophic obstructive cardiomyopathy (HOCM), whose symptoms were refractory to drug therapy. Although left ventricular (LV) outflow tract pressure gradients diminished from 106+/-47 to 62+/-33 mm Hg (p<0.001) by temporary pacing, the residual pressure gradients were >30 mm Hg in the majority of those with concomitant reductions in cardiac output. The DDD pacing was judged as insufficient by the acute study in the majority of patients. A dual-chamber pacemaker was, however, implanted in 11 patients, and the chronic pacing effects were evaluated. All symptoms (syncope, fainting, palpitation and dyspnea) subsided within 1 month. Left ventricular outflow tract pressure gradients diminished from 99+/-56 to 21+/-13 mm Hg (p<0.004) at 1 week after, and to 17+/-12 mm Hg (p<0.002) at 1 year after the implantation, as measured by Doppler echocardiography. Echocardiogram showed disappearance of the systolic anterior motion of the mitral valve, and significant regression of the septal hypertrophy (from 18.5+/-4.3 to 15.7+/-4.1 mm, p<0.04). There was no significant correlation between the acute and chronic pacing effects in the reduction of the pressure gradients or symptomatic improvement. These results suggest that DDD pacemaker implantation is an effective treatment without any serious risks for patients with drug-refractory HOCM. The chronic-pacing effect in the reduction of the pressure gradient, the regression of hypertrophy and symptomatic improvement cannot be predicted by the assessment of temporary DDD pacing.

Adult↗

PubMed1999

Effects of four antigenic fractions of Pasteurella multocida serotype A on phagocytosis of chicken peripheral blood leukocytes.

The effects of four antigenic fractions of Pasteurella multocida serotype A isolated from a duck in the Philippines on the phagocytic activity of chicken peripheral blood leukocytes were studied by a flow cytometer. These fractions were the lipopolysaccharide-protein complex (LPS), crude capsular antigen (CCA), ribosomal fraction (RS) and outer cell layer (OCL). Among these four antigens, only CCA but not LPS RS and OCL, significantly increased the phagocytic activities of mononuclear cells (MNC) and polymorphonuclear cells (PMN). This result indicates that CCA has an immunological property enhancing the phagocytic activities of MNC and PMN.

Animals↗

PubMed1999

Effects of the lipopolysaccharide-protein complex and crude capsular antigens of Pasteurella multocida serotype A on antibody responses and delayed type hypersensitivity responses in the chicken.

The effects of the lipopolysaccharide-protein complex (LPS) and crude capsular antigen (CCA) prepared from Pasteurella multocida serotype A isolated from a duck in the Philippines, on antibody responses to sheep red blood cells (SRBC) and Brucella abortus (BA) and delayed type hypersensitivity (DTH) responses to bovine serum albumin (BSA) in the chickens were studied. Chickens injected subcutaneously with LPS and CCA at 1 and 2 weeks of age and immunized intravenously with the mixed antigens of SRBC and BA, at 3 and 4 weeks of age showed significantly increased antibody responses against both SRBC and BA, when evaluated at 7 days after each immunization. In addition, these chickens sensitized intramuscularly with the emulsion of BSA in complete Freund's adjuvant at 5 weeks of age, and then injected into the wattle with BSA at 7 weeks of age also showed significantly increased DTH responses against BSA, when evaluated at 24 and 48 hr after challenge. These results indicate that LPS and CCA of P. multocida serotype A have a property enhancing humoral and cell-mediated immune responses.

Animals↗

PubMed1999

Transforming growth factor-beta stimulates articular chondrocyte cell growth through p44/42 MAP kinase (ERK) activation.

Transforming growth factor-beta1 (TGF-beta1) stimulates articular chondrocyte cell proliferation and extracellular matrix formation. We reported previously that immediate and transient expression of c-fos mRNA through protein kinase C activation is required for the mitogenic effect of TGF-beta1 on cultured rat articular chondrocytes (CRAC). In gel kinase assays using myelin basic protein (MBP) showed that total cell lysates from cells treated with TGF-beta1 caused rapid phosphorylation of MBP, which suggests the involvement of mitogen-activated protein kinase (MAPK) activation. To identify specific MAPK pathways activated by TGF-beta1, we performed in vitro kinase assays using specific substrates. TGF-beta1 induced a rapid activation of extracellular signal regulated kinase (ERK) with a peak at 5 min, which decreased to basal levels within 240 min after TGF-beta1 stimulation. In contrast, the c-jun N-terminal kinase activity increased only about 2.5-fold after 240 min of stimulation and p38 MAPK activity did not change significantly. ERK activation by TGF-beta1 was also confirmed by in vivo phosphorylation assays of Elk1. However, a specific MEK1 inhibitor, PD98059, significantly decreased TGF-beta1 induced Elk1 phosphorylation in a dose-dependent manner. Furthermore, PD98059 reduced the TGF-beta1-induced cell growth by 40%. These results indicate that TGF-beta1 specifically activates MEK1 and subsequent ERK pathways in CRAC, and that the activation of this MAPK pathway plays a role in the mitogenic response to TGF-beta1.

Animals↗

PubMed1999

cDNA cloning and chromosomal mapping of rat Smad2 and Smad4 and their expression in cultured rat articular chondrocytes.

Smad proteins are known to transduce signalling of TGF-beta receptor superfamily. We report here the entire sequences of rat Smad2 and Smad4 which have not been identified yet. Entire sequences were identified by degenerated polymerase chain reaction and following phage library screening and 5' RACE. The predicted amino acid sequences of rat Smad2 and Smad4 are highly conserved among rat, human and mouse. We also mapped these Smads to chromosome 18q.12.3. Unlike endothelial cells, TGF-beta1 stimulates articular chondrocyte proliferation as well as extracellular matrix production, and acts as a repairing agent against cartilage destruction. Since both Smad2 and Smad4 are essential factors for TGF-beta signalling, we examined their expression and regulation in cultured articular chondrocytes. Northern blot analysis showed that TGF-beta1 significantly increased the mRNA level of Smad2 but not of Smad4 in a dose- and time-dependent manner, suggesting that the augmentation of TGF-beta1 action is caused by increasing the expression of the downstream signalling molecule.

Amino Acid Sequence↗

PubMed1999

Short-term treatment with troglitazone decreases bone turnover in patients with type 2 diabetes mellitus.

Poorly controlled type 2 or non-insulin dependent diabetes mellitus (NIDDM) patients exhibit high bone turnover, which decelerate with treatment according to the degree of improvement in glycemic control. In adults, higher bone turnover results in rapid bone loss. Therefore, deceleration of bone turnover is beneficial for bone. Troglitazone (Tro), a new anti-diabetic drug, is a thiazolidinedione (TZD) which promotes adipocyte differentiation by activating peroxisome proliferator activated receptor gamma (PPARgamma). Because, in the bone marrow, adipocytes and osteoblasts originate in common mesenchymal stem cells that are also essential for osteoclastogenesis, TZDs may directly affect bone metabolism. Thus, we examined the effects of Tro on metabolic bone markers in type 2 DM patients. Tro (400 mg/day) was administered to 33 type 2 DM patients for four weeks. The day before and four weeks after starting Tro, serum and urine samples were collected after overnight fasting. Metabolic bone markers and glycemic indices were assessed. As bone resorption markers, urinary free and total deoxypyridinoline as well as urinary collagen type I C-terminal telopeptide were measured; as bone formation markers, serum bone type and total alkaline phosphatase (BALP and ALP) levels along with osteocalcin (OC) were used. No significant changes in fasting plasma glucose or HbA1c levels were observed in our short-term treatment with Tro. All the bone resorption markers, BALP and ALP were significantly decreased. OC was not significantly changed. The discrepant changes of OC from all the other metabolic bone markers suggest limitation of the use of OC as a reliable bone formation marker in diabetics. Our results that Tro decreased metabolic bone markers before significantly improving glucose metabolism suggest that it has direct effects on bone and decreased bone turnover. TZDs may spare bone mass in NIDDM subjects through its dual effects on glucose and bone metabolism.

Aged↗