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Biomedical subjects

H Ishida

Publications and source records attributed to H Ishida.

At least 271 records · Page 15Linked to original sources

Ganglioside GM(1a) on the cell surface is involved in the infection by human rotavirus KUN and MO strains.

Rotavirus is the most common cause of severe gastroenteritis in infants and children worldwide. The cell attachment of most animal rotaviruses, which belong to the neuraminidase-sensitive strains, requires sialic acid residues on the host cell membranes. On the other hand, most human rotaviruses are classified as neuraminidase-insensitive strains. The involvement of gangliosides on the host cell surface in human rotavirus infection was investigated by immunostaining analysis of target cells, and by assaying the neutralization of infection by rotavirus and the blocking of target cellular receptors. In host cells (MA104 cells) pretreated with Arthrobacter ureafaciens neuraminidase, which were still infected by human rotaviruses (KUN and MO strains), GM(3) was hydrolyzed markedly by the neuraminidase, while GM(1a) was not hydrolyzed at all. Infection by the rotaviruses was strongly inhibited by exogenous ganglioside GM(1a), but not GA(1). Infection was also inhibited by pretreatment of the MA104 cells with cholera toxin B-subunit, which specifically blocked ganglioside GM(1a) on the plasma membrane. The treatment of MA104 cells with the endoglycoceramidase attenuated human rotavirus infection. From these findings, we concluded that GM(1a) on the plasma membrane of the host cells was involved in the infection by human rotavirus KUN and MO strains.

Animals↗

Primary leiomyosarcoma of the greater omentum.

We report a case of primary greater omental leiomyosarcoma successfully resected by omentectomy. Palpation of a painless abdominal mass at physical examination motivated medical imaging examination. Ultrasound visualized accurately the internal structure of the lesion but failed to determine the site of origin. Computed tomography and angiography determined the greater omental origin of the tumor before surgery. A review of the literature is also presented.

Adult↗

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↗

Use of a genetic approach to evaluate the consequences of inhibition of efflux pumps in Pseudomonas aeruginosa.

Drug efflux pumps in Pseudomonas aeruginosa were evaluated as potential targets for antibacterial therapy. The potential effects of pump inhibition on susceptibility to fluoroquinolone antibiotics were studied with isogenic strains that overexpress or lack individual efflux pumps and that have various combinations of efflux- and target-mediated mutations. Deletions in three efflux pump operons were constructed. As expected, deletion of the MexAB-OprM efflux pump decreased resistance to fluoroquinolones in the wild-type P. aeruginosa (16-fold reduction for levofloxacin [LVX]) or in the strain that overexpressed mexAB-oprM operon (64-fold reduction for LVX). In addition to that, resistance to LVX was significantly reduced even for the strains carrying target mutations (64-fold for strains for which LVX MICs were >4 microg/ml). We also studied the frequencies of emergence of LVX-resistant variants from different deletion mutants and the wild-type strain. Deletion of individual pumps or pairs of the pumps did not significantly affect the frequency of emergence of resistant variants (at 4x the MIC for the wild-type strain) compared to that for the wild type (10(-6) to 10(-7)). In the case of the strain with a triple deletion, the frequency of spontaneous mutants was undetectable (<10(-11)). In summary, inhibition of drug efflux pumps would (i) significantly decrease the level of intrinsic resistance, (ii) reverse acquired resistance, and (iii) result in a decreased frequency of emergence of P. aeruginosa strains highly resistant to fluoroquinolones in clinical settings.

Anti-Infective Agents↗

Mutations in exons 2 and 3 of the cationic trypsinogen gene in Japanese families with hereditary pancreatitis.

BACKGROUND/AIMS: Single-point mutations in the cationic trypsinogen gene have been reported in hereditary pancreatitis kindreds in the white population. The aim of the present study was to investigate whether similar gene mutations are present in Japanese hereditary pancreatitis kindreds. METHODS: All five exons of the cationic trypsinogen gene were amplified by polymerase chain reaction and sequenced in six Japanese families with hereditary pancreatitis. RESULTS: Two types of single-point mutation in the cationic trypsinogen gene, which were identical with those reported in white families with hereditary pancreatitis, were observed in separate Japanese families with hereditary pancreatitis: 21Asn (AAC) to Ile (ATC) (N21I) in exon 2 and 117Arg (CGC) to His (CAC) (R117H) in exon 3. Pancreatitis occurred at more advanced ages in patients with the N21I mutation than in those with the R117H mutation. Besides normal polymorphisms in exons 4 and 5, no mutation was found in patients in the remaining four families with hereditary pancreatitis, 21 patients with sporadic chronic pancreatitis, or five normal subjects. CONCLUSIONS: These results show heterogeneity, but no racial specificity, in the cationic trypsinogen gene mutations in hereditary pancreatitis kindreds. A distinctive clinical feature for each of the mutation types is suggested: adult onset for the N21I mutation and childhood onset for the R117H mutation.

Adolescent↗

An insulinotropic effect of vitamin D analog with increasing intracellular Ca2+ concentration in pancreatic beta-cells through nongenomic signal transduction.

The effect of 1alpha,25-dihydroxylumisterol3 (1alpha,25(OH)2lumisterol3) on insulin release from rat pancreatic beta-cells was measured to investigate the nongenomic action of vitamin D via the putative membrane vitamin D receptor (mVDR). 1Alpha,25(OH)2lumisterol3, a specific agonist of mVDR, dose-dependently augmented 16.7 mM glucose-induced insulin release from rat pancreatic islets and increased the intracellular Ca2+ concentration ([Ca2+]i), though not increasing Ca2+ efficacy in the exocytotic system. These effects were completely abolished by an antagonist of mVDR, 1beta,25-dihydroxyvitamin D3 (1beta,25(OH)2D3), or by a blocker of voltage-dependent Ca2+ channels, nitrendipine. Moreover, both [Ca2+]i elevation, caused by membrane depolarization, and sufficient intracellular glucose metabolism are required for the expression of these effects. 1Alpha,25(OH)2lumisterol3, therefore, has a rapid insulinotropic effect, through nongenomic signal transduction via mVDR, that would be dependent on the augmentation of Ca2+ influx through voltage-dependent Ca2+ channels on the plasma membrane, being also linked to metabolic signals derived from glucose in pancreatic beta-cells. However, further investigations will be needed to discuss physiologically the meaning of insulinotropic effects of vitamin D through mVDR.

Animals↗

Studies of the active substances in herbs used for hair treatment. II. Isolation of hair regrowth substances, acetosyringone and polyporusterone A and B, from Polyporus umbellatus Fries.

Fractionation of the 50% ethanol extract of Polyporus umbellatus Fries by column chromatography on Amberlite XAD-2, silica gel, Sephadex LH-20 and octadecyl silica gel (ODS) (C18)) monitored by a hair-regrowth activity assay, afforded three active principles, 1, 2 and 3. The structures of 1, 2 and 3 were determined as acetosyringone, polyporusterone A, and polyporusterone B by comparison of their spectral data with that of authentic samples, respectively. The effects of several compounds related to acetosyringone, 3,4-dihydroxybenzaldehyde or polyporusterone A on hair regrowth were also investigated.

Animals↗

New 6-O-acyl isoflavone glycosides from soybeans fermented with Bacillus subtilis (natto). I. 6-O-succinylated isoflavone glycosides and their preventive effects on bone loss in ovariectomized rats fed a calcium-deficient diet.

Three new 6-O-acylated isoflavone glycosides were isolated from soybeans fermented with Bacillus subtilis (natto) and identified as daidzein 7-O-beta-(6''-O-succinyl)-D-glucoside (1), genistein 7-O-beta-(6''-O-succinyl)-D-glucoside (2), and glycitein 7-O-beta-(6''-O-succinyl)-D-glucoside (3) on the basis of spectral data and chemical transformations. During fermentation, the content of the isoflavone glycosides first decreased and then increased, whereas the corresponding 6''-O-succinyl derivatives first accumulated and then decreased, in either soybeans or soybean cooking solution. These changes suggest that enzymatic interconversion of isoflavone glycosides and the corresponding 6''-O-succinylated derivatives occurs in these media during fermentation. The 6-O-succinylated isoflavone glycosides 1, 2 and 3 accounted for 4.8, 7.2 and 0.6%, respectively, of the total isoflavones in commercial fermented soybeans (Japanese natto). Oral administration of 1 or 2 alone for 4 weeks at a dose of 50 mg/kg/d prevented bone loss in ovariectomized (ovx) rats fed a calcium-deficient diet, being as effective as the positive controls, daidzin and genistin, respectively. Compound 1 seems to be proestrogenic, like daidzin, which suppresses bone resorption to prevent bone loss after ovariectomy by directly acting on bone sites, while 2 appears to have a different mechanism of action, like that of genistin.

Animals↗

Studies of the active substances in herbs used for hair treatment. III. Isolation of hair-regrowth substances from Polygara senega var. latifolia TORR. et GRAY.

Four active principles, 1, 2, 3 and 4, were isolated from Polygara senega var. latifolia TORR. et GRAY by a combination of partition and column chromatography on silica gel and octadecyl silica gel (ODS), monitored by a hair-regrowth activity assay. Compounds 1, 2, 3 and 4 were identified as senegose A, senegin II, senegin III, and senegasaponin b by comparison of their spectral data with those of authentic samples.

Animals↗

Study of the pharmacological effect of the bile salt, sodium scymnol sulfate, from Rhizoprionodon acutus. III. Protective effect of scymnol against vascular endothelial cell damage in a rat peripheral arterial occlusion model.

The prophylactic action of scymnol in a rat peripheral arterial occlusion model, involving injection of 5% lactic acid into the femoral artery, was investigated. Increases in serum lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) activities and in plasma levels of thrombin and antithrombin III complex (TAT) were observed in this model 3 h after injection of lactic acid. Changes in LDH activity were characterized by increases in isozymes LDH4 and LDH5 and an elevated LDH4/LDH5 ratio. The ratio of the LDH4 to LDH5 increments was similar to that seen in a rat endothelial cell culture. Oral preadministration of scymnol had a preventive effect on the development of lesions in this model. It significantly reduced the LDH4 and LDH5 activity, the LDH4/LDH5 ratio and the TAT levels dose-dependently over the range 1, 3 or 10 mg/kg, compared with the values in control rats. However, its administration after lactic acid injection, or to sham-operated rats was ineffective, even at a dose of 10 mg/kg. The effects of scymnol were also compared with those of ticlopidine and argatroban. The findings show that scymnol may be useful in preventing thrombotic peripheral arterial occlusive disorders and that it potently protects endothelial cells against lactic acidosis in this model.

Alanine Transaminase↗

Study of the pharmacological effect of the bile salt, sodium scymnol sulfate, from Rhizoprionodon acutus. IV. Effects of naturally occurring bile alcohols, bile acids and their conjugates on lesion development and vascular endothelial cell injury in a rat peripheral arterial occlusion model.

A series of naturally occurring bile alcohols, bile acids and their conjugates has been investigated as part of our studies to develop unique anticoagulants with a potent prophylactic effect against vascular endothelial cell injury induced by lactic acidosis in vivo and in vitro. In an in vivo rat peripheral arterial occlusion model induced by lactic acid injection, oral administration of a single dose of 3 mg/kg scymnol significantly inhibited edematous swelling and development of lower limb lesions, including gangrene, and reduced changes in clotting system functions and serum lactate dehydrogenase activity. It had no effect on clotting system functions in sham-operated rats. The structure-activity relationship suggests that the [24R-(+)-5beta-cholestane-3alpha,7alpha,24,26-pento l] or [3alpha,7alpha-dihydroxy-5beta-cholanic acid] structure is important for a potent prophylactic effect following oral administration. Intravenous administration of a single dose of 0.3 mg/kg sodium (25S)-scymnol sulfate or scymnol prevented lesion progression as effectively as oral administration of scymnol. Sodium (25S)-scymnol sulfate and ursodeoxycholic acid showed clear protective effects against cultured vascular endothelial cell damage due to lactic acidosis which were dose-dependent. The above results suggest that bile steroids such as scymnol, sodium (25S)-scymnol sulfate, ursodeoxycholic acid, and chenodeoxycholic acid may play a role in protecting endothelial cells against injury caused by lactic acidosis. These compounds are candidates for novel anti-ischemic drugs that act by specifically protecting vascular endothelial cells.

Animals↗

Antagonistic effect of N-methyltyramine on alpha2-adrenoceptor in mice.

We examined the effect of N-methyltyramine (NMT) on alpha2-adrenoceptor. NMT (10(-8)-10(-3) M) inhibited the binding of [3H]p-aminoclonidine to alpha2-adrenoceptor dose-dependently. However, the IC50 value for NMT (5.53 x 10(-6) M) was higher than that for RX821002, an alpha2-adrenoceptor antagonist (1.07 x 10(-8) M). RX821002 (5 mg/kg, i.p.) inhibited hypermotility induced by scopolamine (8 mg/kg, s.c.) in male ddY mice. NMT (20 or 100 mg/kg, i.p.) was found to have a dose-dependent inhibitory effect similar to that of RX821002. These findings indicate that NMT has the properties of an alpha2-adrenoceptor antagonist. However, the affinity of NMT for alpha2-adrenoceptor is weaker than that of RX821002.

Adrenergic alpha-2 Receptor Antagonists↗

Haloperidol prolongs diastolic phase of Ca(2+) transient in cardiac myocytes.

Haloperidol (HPL), a widely used antipsychotic drug, is known to induce serious ventricular arrhythmias. However, the mechanism underlying their induction is not clear. We therefore examined the effects of HPL on the intracellular Ca(2+) ([Ca(2+)](i)) transient and on cell motion in cultured cardiac myocytes, as well as the pathways involving the HPL-induced abnormality of Ca(2+) homeostasis. HPL prolonged the diastolic phase of the Ca(2+) transient, with a mid-diastolic re-elevation of [Ca(2+)](i). The re-elevation of [Ca(2+)](i) was shown to be provoked by Ca(2+) release from sarcoplasmic reticulum (SR), which can trigger delayed afterdepolarization, the major arrhythmogenic factor. The re-elevation of [Ca(2+)](i) coincided with cell re-contraction during diastole. The induction of this abnormality by HPL appears to be independent of the mechanisms of the antipsychotic action.

Animals↗

Decreased expression of t-SNARE, syntaxin 1, and SNAP-25 in pancreatic beta-cells is involved in impaired insulin secretion from diabetic GK rat islets: restoration of decreased t-SNARE proteins improves impaired insulin secretion.

The physiological role of soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor (SNARE) proteins in insulin exocytosis has been reported in pancreatic beta-cells. To determine whether the beta-cells of GK rats, a nonobese rodent model of type 2 diabetes, exhibit abnormalities in their SNARE proteins, we studied the expression and function of target (t)-SNAREs, syntaxin 1A, and synaptosomal-associated protein of 25 kDa (SNAP-25) in GK rat islets. Although insulin release and insulin content of islets isolated from 12-week-old GK rats were reduced, the proinsulin biosynthetic rate was about twofold higher than that in control rat islets, and no change in the preproinsulin mRNA level was observed. Pulse-chase experiments suggested the increased degradation of insulin in GK rat islets. Immunoblot analysis revealed that protein levels of syntaxin 1A and SNAP-25 in GK rat islets decreased to approximately 60% of the levels in control rat islets. We then examined whether the restoration of the decreased expression of t-SNAREs to the normal level in GK rat islets affected insulin secretion. Restoration was achieved by the overexpression of syntaxin 1A and SNAP-25 via the recombinant adenovirus-mediated gene transduction system, which recovered levels of these proteins to almost control levels. Glucose-stimulated insulin release from AdexlCA syntaxin 1A and Adex1CA SNAP-25-infected GK rat islets increased up to approximately 135 and 200%, respectively, of those from uninfected GK rat islets, although no difference in basal (2.2 mmol/l glucose) insulin release was evident between them. We conclude that decreased expression of t-SNAREs in GK rat islets is in part the defect responsible for impaired insulin secretion.

Animals↗

[alpha-Glucosidase inhibitor].

Oral anti-diabetic agents with hypoglycemic action via mechanisms distinct from the sulfonylureas have recently been developed. One of these, alpha-glucosidase inhibitor slows the absorption rate of carbohydrate from the small intestine. Effects of voglibose on glycemic control and on the function of pancreatic islets were evaluated using Goto-Kakizaki (GK) rats with non-insulin-dependent diabetes mellitus (NIDDM). Insulin secretory capacity in response to glucose of islets was significantly improved after 8-week administration of voglibose. The treatment increased the insulin content of the islets to almost twice that in untreated controls. Thus, the treatment can restore the deteriorated islet function of GK rats, possibly through protection from glucose toxicity.

Administration, Oral↗

[Clinical evaluation of serum cytokine from patients with collagen diseases].

PURPOSE: Systemic autoimmune diseases such as systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) are characterized by an imbalance of cytokine production. To clarify the relationship between the profile of cytokines and the pathophysiology of systemic autoimmune diseases, we estimated the cytokine levels in sera from patients with several systemic autoimmune diseases. METHOD: Serum cytokine levels in patients with unclassified connective tissue diseases were measured using ultrasensitive specific enzyme-linked immunosorbent assay (ELISA). RESULT: These patients were diagnosed using the established category by further examinations within a 2-year period. Sera from patients with SLE contained higher titers of IL-10, and equal levels of IFN gamma and TNF alpha compared with those of normal controls. Patients with progressive systemic sclerosis (PSS) showed lower titers of IL-10 and higher titers of IFN gamma and TNF alpha in their sera than those of healthy controls. Seronegative rheumatoid arthritis (snRA) patients had a higher amount of IL-10 and TNF alpha, equivalent level of IFN gamma in their sera compared to those of controls. Moreover, patients with Sjögren's syndrome (SS) showed higher titers of IL-10 and TNF alpha, and an equivalent level of IFN gamma in their sera compared to healthy volunteers. CONCLUSION: Based on these findings, for the differential diagnosis of patients with systemic autoimmune diseases such as SLE, PSS, snRA and SS, it may be useful to measure the levels of cytokines such as IL-10, IFN gamma, and TNF alpha in their sera.

Autoimmune Diseases↗

Characteristic loss of heterozygosity in chromosome 3P and low frequency of replication errors in sporadic renal cell carcinoma.

PURPOSE: A high frequency of genetic loss at 4 loci on chromosome 3p has been shown in human sporadic renal cell carcinomas (RCCs), but the relative contribution of each locus is not well known, and the involvement of DNA replication errors (RERs) in carcinogenesis of RCCs remains unclear. We report the simultaneous comparison of genetic loss at the 4 chromosome 3p loci and RERs in sporadic RCCs. MATERIALS AND METHODS: DNA was extracted from 33 Japanese sporadic RCC samples, and examined for loss of heterozygosity (LOH) and RERs by amplification of 14 microsatellite regions. LOH of the von Hippel Lindau (VHL) gene was analyzed by a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. The target sequences of RER, transforming growth factor beta type II receptor (TGFbetaRII) and Bcl-2-associated X protein (BAX) genes were amplified and analyzed for mutations by sequencing. RESULTS: LOH of the VHL gene was observed in 53.3% of RCCs, a higher frequency than that of the 4 regions 3p12-p13 (18.8%), 3p14.2 (17.4%), 3p21 (21.2%) and 3p25-p26 except for VHL (31.3%). There were no RERs in 14 microsatellite regions, including the mononucleotide (A)10 repeats of the TGFbetaRII gene and (G)8 repeats of the BAX gene. CONCLUSION: Japanese sporadic RCCs were characterized by predominant loss of VHL gene and low contribution of the other 3 candidate RCC tumor suppressor genes. RERs, mostly caused by a defect of DNA mismatch repair, might only rarely be involved in the carcinogenesis of sporadic RCCs.

Carcinoma, Renal Cell↗