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Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 397 records · Page 22Linked to original sources
PubMed1998

Double cardiac rupture after direct infarct coronary angioplasty: report of a case.

The occurrence of double cardiac rupture (DCR) after a successful direct infarct coronary angioplasty (DICA) is extremely uncommon. We describe herein the case of a patient who underwent delayed DICA and despite successful recanalization, subsequently suffered DCR, as a postinfarction ventricular septal defect (PIVSD) with left ventricular free wall rupture (LVFWR). Emergency surgery was performed, and the patient is now doing well more than 2 years after his operation. The possible mechanisms of DCR after delayed DICA are discussed following the presentation of this unusual case.

Aged↗
PubMed1998

Satigrel, a new antiplatelet agent, inhibits platelet accumulation in prosthetic arterial grafts.

BACKGROUND: Early and late vascular obstruction are both related to platelet adhesion and aggregation in the grafts. We assessed the effect of satigrel, a new oral antiplatelet agent, on the accumulation of indium-labeled platelets in knitted Dacron grafts inserted proximal to the femoral artery. METHODS: Nine patients with arteriosclerosis obliterans receiving grafts were treated with satigrel, and 10 others were enrolled as untreated controls. Scintigraphy was performed in postoperative weeks 2 and 4, and the ratio of the scintillation count of the graft to that of the native artery was calculated to assess platelet accumulation. RESULTS: In both weeks 2 and 4, the ratio was significantly smaller in the satigrel group than in the control group for the whole graft, the proximal anastomosis, and the distal anastomosis. CONCLUSIONS: Satigrel significantly inhibited platelet accumulation in vascular grafts and thus may be useful for preventing postoperative graft occlusion.

Aged↗
PubMed1998

Simultaneous total aortic replacement without a sternotomy incision.

Total aortic replacement is preferably performed by staged operations, and reports of a simultaneous operation are few. In these reports, both a median sternotomy and a thoracoabdominal incision are employed. We report a patient who successfully underwent simultaneous total aortic replacement without a sternotomy incision. The technique and the feasibility of the operation are discussed.

Aortic Dissection↗
PubMed1998

Evaluation of 18-hour lung preservation with oxygenated blood for optimal oxygen delivery.

BACKGROUND: Previous studies have shown that availability of oxygen during lung preservation to maintain aerobic metabolism may be essential for the optimal viability of preserved lung tissue. The purpose of this study was to evaluate lung preservation with oxygenated blood for optimal oxygen delivery to the lung graft in a rabbit model. METHODS: Eighteen excised rabbit lungs were flushed and stored for 18 hours at 10 degrees C with one of the following: Euro-Collins solution (EC; n=6), oxygenated homologous blood (OB; n=6), or low-potassium dextran solution (LPD; n=6). Poststorage lung functions were evaluated with isolated, blood-perfused lung model for 10 minutes. RESULTS: The mean oxygen tensions after reperfusion for the EC, OB, and LPD groups (47.0+/-2.8, 76.9+/-13.1, 96.2+/-10.9 mm Hg at 10 minutes, respectively) were significantly different throughout the perfusion period (EC < OB < LPD, p < 0.05; EC < LPD, p < 0.01). Pulmonary artery pressure during the reperfusion period in the EC group (35.8+/-4.4 mm Hg at 10 minutes) was higher than that in the OB and LPD groups (29.8+/-4.3 and 22.4+/-2.2 mm Hg, respectively) (EC > OB, EC > LPD, p < 0.05). However, the E-selectin level in the reperfused blood in the OB group (5.04+/-0.24 ng/mL) was significantly elevated compared with that in other groups (EC, 3.56+/-0.54; LPD, 2.92+/-0.35 ng/mL, p < 0.05), which indicated enhanced neutrophil recruitment in the OB group. Comparisons of thrombomodulin and endothelin among the three groups did not reach statistical significance. CONCLUSIONS: We conclude that OB may enhance lung preservation as compared with EC solution, probably through its enriched oxygen delivery during storage and extracellular composition. However, the availability of oxygenated blood does not exceed that of LPD solution because of augmented neutrophil recruitment, which may activate neutrophil-endothelial interactions.

Animals↗
PubMed1998

Effects of troglitazone on hepatic and peripheral insulin resistance induced by growth hormone excess in rats.

It is well known that short-term growth hormone (GH) administration in humans and animals induces insulin resistance and glucose intolerance. The purpose of the present study was to clarify whether troglitazone, a new insulin-sensitizing drug of the thiazolidinedione class, counteracts the insulin antagonistic effects of recombinant human (rh) GH on glucose metabolism in rats. Male Wistar rats weighing 184 to 226 g were treated either with rhGH (n = 8) or rhGH plus troglitazone (n = 8). rhGH (20 IU/kg body weight/d) was given by subcutaneous injection twice daily for 2 days. Troglitazone was given at 100 mg/kg/d orally for 5 days before and 2 days during rhGH. Saline was injected to the control rats (n = 7). Euglycemic clamp studies with an insulin infusion rate of 8 mU/kg/min were performed in these rats after an overnight fast. Hepatic glucose output (HGO), glucose infusion rate (GIR), and glucose disappearance rate (GDR) were measured. Fasting levels of plasma glucose (6.6 +/- 0.1, 6.1 +/- 0.3, 6.5 +/- 0.2 mmol/L), insulin (187.5 +/- 24.1, 206.4 +/- 24.1, 182.3 +/- 31.0 pmol/L), and serum free fatty acid (FFA) (1.58 +/- 0.18, 1.43 +/- 0.16, 1.61 +/- 0.25 mEq/L) were comparable among rats treated with rhGH, rhGH plus troglitazone, and controls, respectively. Basal HGO was also comparable among the three treatment groups. HGO was suppressed significantly during the hyperinsulinemic glucose clamp in control rats, but not in rhGH rats. When troglitazone was coadministered with rhGH, suppressibility of HGO during the glucose clamp was comparable to that of controls. GIR (13.5 +/- 4.5 v 24.1 +/- 4.1 mg/kg/min) and GDR (18.1 +/- 5.8 v 30.3 +/- 5.2 mg/kg/min) were decreased by rhGH treatment compared with control values. They returned to normal levels in rats treated with both rhGH and troglitazone (GIR, 22.4 +/- 5.9; GDR, 24.7 +/- 7.1). From these results, it is evident that rhGH treatment impaired insulin's ability to suppress HGO and stimulate peripheral glucose utilization. Troglitazone could block the insulin antagonistic effects of GH on hepatic glucose output and peripheral glucose utilization.

Administration, Oral↗
PubMed1998

Effects of troglitazone on dexamethasone-induced insulin resistance in rats.

Troglitazone, a thiazolidinedione derivative, has been shown to counteract insulin resistance in obesity and non-insulin-dependent diabetes mellitus (NIDDM). To test its effects on dexamethasone-induced insulin resistance, we measured hepatic glucose production (HGP) and the insulin-stimulated glucose disposal rate (Rd) by a euglycemic-hyperinsulinemic glucose clamp technique coupled with 3-3H-glucose infusion in male Wistar rats treated with low-dose dexamethasone ([LoDex] 0.05 mg/kg/d, n = 7), high-dose dexamethasone ([HiDex] 0.1 mg/kg/d, n = 7), or dexamethasone plus troglitazone (LoDex + T, n = 8; HiDex + T, n = 6). Dexamethasone was injected subcutaneously for 4 days. Troglitazone was administered orally at 20 mg/d for 3 days before and for 4 days along with the dexamethasone treatment. The glucose clamp study was performed after an overnight fast in chronically catheterized conscious rats with a continuous insulin infusion of 57.4 pmol/kg/min. Basal HGP was comparable among the control (45.8 +/- 2.1 micromol/kg/min, n = 7), LoDex (47.9 +/- 4.7 micromol/kg/min), LoDex + T (46.0 +/- 2.6 micromol/kg/min), and HiDex + T (54.7 +/- 3.4 micromol/kg/min) groups. It increased about twofold in the HiDex group (80.1 +/- 5.2 micromol/kg/min, P < .05 v control). Under hyperinsulinemia, HGP was suppressed to a similar level in the control (11.3 +/- 8.8 micromol/kg/min), LoDex (10.2 +/- 8.4 micromol/kg/min), and LoDex + T (7.8 +/- 7.9 micromol/kg/min) groups. The suppressive effect of insulin on steady-state HGP during the clamp was impaired in HiDex (63.7 +/- 9.7 micromol/kg/min, P < .05) and HiDex + T (64.0 +/- 6.5 micromol/kg/min, P < .05). Rd decreased 27% in LoDex (81.5 +/- 5.8 micromol/kg/min, P < .05) and 36% in HiDex (71.3 +/- 9.4 micromol/kg/min, P < .05) compared with the controls (111.4 +/- 7.4 micromol/kg/min). Troglitazone prevented the decrease in Rd in LoDex + T (102.6 +/- 5.7 micromol/kg/min), but not in HiDex + T (67.0 +/- 6.4 micromol/kg/min). These results indicate that the development of peripheral insulin resistance was prevented by troglitazone in LoDex rats. Troglitazone may be a useful drug to treat steroid-induced diabetes.

Animals↗
PubMed1998

Amino acid sequence of ferredoxin from Physalis alkekengi var. francheti.

The complete amino acid sequence of [2Fe-2S] ferredoxin from Physalis alkekengi var. francheti has been determined by automated Edman degradation of the entire Cm-protein and of the peptides obtained by trypsin and endoproteinase Asp-N digestions. This ferredoxin exhibited ten, ten, and nine differences respectively in the amino acid sequence, when compared with the ferredoxins of Datura stramonium, D. metel, and D. arborea, but 21-28 differences for other angiosperms, and 34-37 differences for fern and horsetails. These results are in harmony with the taxonomic position for these plants.

Amino Acid Sequence↗
PubMed1998

Histamine H1-receptor-mediated increase in the Ca2+ transient without a change in the Ca2+ current in electrically stimulated guinea-pig atrial myocytes.

The effects of histamine on the intracellular Ca2+ concentration ([Ca2+]i), action potential and membrane currents were assessed in single atrial myocytes prepared from guinea-pigs. Histamine caused a concentration-dependent increase in the [Ca2+]i transient in indol/AM loaded myocytes when stimulated electrically at 0.5 Hz. However, the maximum increase in [Ca2+]i transient produced by histamine was less than 50% of that elicited by isoprenaline. The histamine-induced increase in [Ca2+]i transient was significantly inhibited by chlorpheniramine, but not by cimetidine. Pretreatment with nifedipine nearly completely suppressed the histamine-induced increase in [Ca2+]i transient. Cyclopiazonic acid did not affect the histamine response. In the whole-cell current-clamp mode of the patch-clamp method, both histamine and isoprenaline prolonged action potential duration (APD) in atrial myocytes. In the presence of Co2+ or nifedipine, the isoprenaline-induced APD prolongation was abolished and an APD shortening effect was manifested, while histamine still increased APD. The APD prolongation elicited by histamine was reversed by chlorpheniramine. In the voltage-clamp mode, the histamine-sensitive membrane current was inwardly rectifying and reversed close to the calculated value of the K+ equilibrium potential. Histamine had no apparent effect on L-type Ca2+ current, in contrast to the pronounced effect of isoprenaline. These results indicate that in guinea-pig atrial myocytes stimulation of H1-receptors with histamine does not directly activate Ca2+ channels but causes an elevation of [Ca2+]i transient by increasing Ca2+ influx through the channels during the prolonged repolarization of action potentials resulting from inhibition of the outward K+ current.

Action Potentials↗
PubMed1998

In vivo and in vitro effects of AVP and V1a receptor antagonist on Cushing's syndrome due to ACTH-independent bilateral macronodular adrenocortical hyperplasia.

We examined the possibility that AVP and V1a receptors were involved in regulating cortisol production in a 49 year old man with ACTH-independent bilateral macronodular adrenocortical hyperplasia (AIMAH), and investigated the effects of a V1a receptor antagonist. An i.v. injection of a small dose (0.1 or 0.3 U) of AVP, insulin-induced hypoglycaemia, upright posture tests, and oral administration of a V1a receptor antagonist (OPC-21268; 300 mg), and its repeated administration at a dose of 600 mg/day for 8 days were performed. An in vitro study of dispersed cells obtained from resected AIMAH tissue was also conducted. Plasma ACTH, AVP and cortisol levels and 24-h urinary free cortisol excretion were measured in the in vivo studies and cortisol concentrations in incubation media in the in vitro study. Injection of small doses of AVP stimulated cortisol secretion without any elevation of plasma ACTH. Insulin-induced hypoglycaemia caused a rise in plasma AVP followed by an increase in plasma cortisol. Although plasma cortisol levels were not affected by single or repeated administrations of OPC-21268, 24-h urinary free cortisol excretion was significantly decreased by the repeated treatment. In the in vitro study, more cortisol was stimulated by AVP from adrenal cells of the AIMAH tissue than from those of a normal adrenal gland, and this secretion was completely suppressed by OPC-21268. These results suggested that hypersensitivity to AVP may have contributed to overproduction of cortisol in this case of ACTH-independent bilateral macronodular adrenocortical hyperplasia, and may have contributed to its pathogenesis.

Adrenal Cortex↗
PubMed1998

Transcription factor CP2 is essential for lens-specific expression of the chicken alphaA-crystallin gene.

BACKGROUND: Lens-specific transcriptional activation of the chicken alphaA-crystallin gene is controlled by the distal and proximal enhancers, alphaCE1 and alphaCE2, respectively. Analysis using specific monoclonal antibodies against purified alphaCE1-binding factor alphaCEF1 revealed that alphaCEF1 is composed of two distinct subunits. RESULTS: We have demonstrated that one of the subunits of alphaCEF1 is encoded by chicken ubiquitous transcription factor CP2 (cCP2), which is homologous to mouse CP2, and human CP2/LBP-1/LSF-1. Electrophoretic mobility shift assays and cross-linking experiments showed that alphaCEF1 and bacterially expressed cCP2 form a tetramer. Overexpression of cCP2 activates transcription through alphaCE1, but a mutant cCP2 lacking the DNA-binding domain reduced the transcription to basal levels. Although cCP2 binds to the CP2 template from the mouse alpha-globin promoter, it fails to promote transcription through this template. Element substitution experiments between alphaCE1 and the CP2 template revealed that the lens-specific enhancer activity of alphaCE1 is due to the 6 bp sequence (-139/-134; lens-specific element (LSE)) adjacent to the 3' of the cCP2 binding site within alphaCE1. CONCLUSION: We have shown that the tetrameric transcription factor cCP2 is essential for lens-specific transcription of the chicken alphaA-crystallin gene, although it is ubiquitously expressed. We propose a model where cCP2 cooperates with a putative lens-specific factor which binds to LSE.

Amino Acid Sequence↗
PubMed1998

Differential diagnosis of mucin-producing tumors of the pancreas by intraductal ultrasonography and peroral pancreatoscopy.

BACKGROUND AND STUDY AIMS: Although mucin producing tumors of the pancreas have been recently recognized as premalignant or malignant neoplasms, their diagnosis and management have been undetermined as yet. The aim of this study was to evaluate the capability of intraductal ultrasonography (IDUS) and peroral pancreatoscopy (PPS) in the differential diagnosis of mucin-producing tumors compared to that of other diagnostic tools. PATIENTS AND METHODS: From 1986 to 1997, 31 patients with mucin-producing tumors of the pancreas underwent surgery. RESULTS: Histologically, in patients with adenocarcinoma, papillary tumorous lesions within the pancreatic ducts were 3 mm or more in maximum height. The detection rates for such lesions were 29% with US, 21% with CT, 86% with EUS, 100% with IDUS and 83% with PPS. In patients with adenocarcinoma, PPS revealed taller papillary lesions with redness and/or capillary vessels. Biopsy and cytology during ERCP and under PPS direct vision had a sensitivity of about 60 % in the differential diagnosis between malignancy and benign diseases. CONCLUSIONS: Mucin-producing tumors of the pancreas with papillary tumorous lesions of 3 mm or more in maximum height should be considered as adenocarcinomas. The combined use of IDUS and PPS with biopsy and cytology is now considered the best for the differential diagnosis of mucin-producing tumors of the pancreas.

Adenocarcinoma, Mucinous↗
PubMed1998

EUS-guided fine aspiration biopsy (FNA)--indications and hazards.

Ultrasound endoscopes with mechanical sector forward scan transducers make it possible to perform FNA under EUS, and drainage by tracing the needle in the ultrasound pictures by using the same monitor unit as for radial scan ultrasound endoscopes for EUS diagnosis. It is important to diagnose the lesions from the histological findings; however, there remain some problems about false negatives, histological diagnosis from very tiny materials, and the risk of disseminating the malignant cells by the procedure.

Biopsy, Needle↗
PubMed1998

Acute exacerbation of autoimmune liver disease associated with hantaviral infection.

Hantavirus is known to cause haemorrhagic fever with renal syndrome (HFRS). Although liver dysfunction has been reported in HFRS, hepatic manifestations of hantaviral infection have not been well described. We describe a case of autoimmune cholangitis in which an exacerbation of hepatitis was associated with hantaviral infection. Seroconversion of both IgG- and IgM-class antibodies to hantavirus was noted coincident with acute exacerbation of hepatitis, which was resolved promptly by treatment with corticosteroid. No extrahepatic manifestations were noted. This case suggests that hantavirus may trigger acute exacerbation of autoimmune liver disease without extrahepatic manifestations and that it may cause community-acquired hepatitis.

Antibodies, Antinuclear↗
PubMed1998

Glucose- and phorbol ester-induced insulin secretion in human insulinoma cells--association with protein kinase C activation.

This study examined the effect of glucose and 12-O-tetradecanoylphorbol-13-acetate (TPA) on insulin secretion in isolated human insulinoma cells. In addition, we analyzed conventional PKC alpha and beta activation in the membrane fractions, respectively. Treatment with 5 mM and 20 mM glucose for 5 min and 20 min resulted in 6-7-fold increases in insulin secretion, and treatment with 1 microM TPA for 5 min also resulted in 3-fold increases in insulin secretion from the basal level. Immunoblot analysis of membrane fractions showed increases in PKC alpha and beta immunoreactivities after treatment with 5 mM, 20 mM glucose and 1 microM TPA. Translocations of PKC alpha after treatment with glucose and TPA were greater than those of PKC beta in membrane fractions. These results suggest that TPA independently provokes insulin secretion via PKC activation and that PKC alpha and beta activation may be involved in insulin secretion in human insulinoma cells.

Adult↗
PubMed1998

Analysis of conserved ambisense sequences within GB virus C.

No analysis has been done of the ambisense of GB virus C (GBV-C). When the anti-genomes of 16 reported sequences of GBV-C were analyzed, nucleotide codons 1758 and 1402 within the anti-genome were conserved initiation and stop codons, respectively. Nucleotide sequences were also determined within the same region of 22 GBV-C strains. The anti-genomes of 38 sequences were translated and a consensus sequence was determined. In accordance with the consensus sequence, overlapping peptides were synthesized and used for the detection of anti-synthetic peptide antibodies by ELISA. The positivity of antibodies among sera with GBV-C RNA was significantly higher than among sera without GBV-C RNA (66.7% vs. 15.6%), regardless of the simultaneous presence of hepatitis B surface antigen or antibodies to hepatitis C virus (P < .05). These results indicated that a novel protein associated with GBV-C might be expressed from the ambisense of this virus.

Antibodies, Viral↗
PubMed1998

Prolongation of allograft survival by administration of mAb specific for the three subunits of IL-2 receptor.

The IL-2 receptor (IL-2R) gamma chain, the so-called common gamma (gamma(c)) chain, which is shared with multiple cytokine receptors, plays important roles in the immune system. Here we assessed the immunosuppressive ability of mAb specific for the gamma(c) chain in induction of cytotoxic T lymphocytes (CTL) and allograft rejection in combination with mAb specific for the alpha and beta chains of IL-2R. CBA/N (H-2k) mice were injected i.p. with allogeneic splenocytes from BALB/c (H-2d) mice, and then administered with combinations of anti-IL-2R alpha, anti-IL-2R beta and anti-gamma(c) mAb or a control mAb. Addition of anti-gamma(c) mAb together with anti-IL-2R alpha and anti-IL-2R beta mAb induced a complete inhibition of CTL response. The numbers and populations of CD4+ CD8- and CD4- CD8+ T cells were not significantly affected by administration of the three anti-IL-2R mAb, whereas NK cells were completely depleted in spleens of mice treated with the anti-IL-2R mAb. Furthermore, skin allograft survival was also significantly prolonged by administration of the three anti-IL-2R mAb. These results suggest that the anti-gamma(c) mAb in combination with anti-IL-2R alpha and anti-IL-2R beta mAb is capable of suppressing induction of CTL and NK cells, resulting in prolongation of skin allograft survival.

Animals↗