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Biomedical subjects

Y Yamaguchi

Publications and source records attributed to Y Yamaguchi.

At least 415 records · Page 23Linked to original sources
PubMed1998

Mechanisms of impairment of endothelium-dependent relaxation to acetylcholine in Watanabe heritable hyperlipidaemic rabbit aortas.

1. The mechanism of impairment of the endothelium-dependent relaxation in response to acetylcholine (ACh) in aortas from Watanabe heritable hyperlipidaemic (WHHL) rabbits was investigated using a modified sandwich (layered) technique. Intact aortas from WHHL rabbits or Japanese white (JW) rabbits as the control were used as donor strips of endothelium-derived relaxing factor (EDRF) and endothelium-denuded aortas from JW rabbits were used as detector strips. The EDRF released from a donor strip could be directly detected as the relaxation response in a detector strip. 2. The endothelium-dependent relaxations in all rabbit arteries were almost abolished by treatment with N(G)-nitro-L-arginine methyl ester (an inhibitor of nitric oxide synthase). 3. The ACh-induced endothelium-dependent relaxations in the donor strips were impaired in WHHL rabbits in comparison with relaxations in JW and heterozygous WHHL rabbits. Similarly, the relaxation in the detector strips induced by EDRF released from donor strips was reduced in WHHL rabbits. There was a good negative correlation between the aortic total cholesterol content in the donor strips and the degree of relaxation in the detector strips from WHHL rabbits. 4. The reduced relaxation in the detector strips when using donor strips with high cholesterol accumulation or atheromatous plaque was not affected by superoxide dismutase plus catalase (scavengers of superoxide anions), indomethacin (an inhibitor of cyclo-oxygenase), ONO-3708 (an antagonist of endoperoxide/thromboxane receptor) and 97-139 (an antagonist of endothelin ET(A) receptor). 5. These results suggest that the mechanism of impaired endothelium-dependent relaxations in atherosclerotic WHHL rabbit aortas may be due to the reduced amount of EDRF, probably nitric oxide, from the endothelium and not due to its inactivation by oxygen-derived free radicals or masking by increased production of endothelium-derived contracting factors.

Acetylcholine↗
PubMed1998

Ruptured aneurysm of the ductus diverticulum into the pulmonary artery in a man: a successful repair.

Aneurysm of the ductus diverticulum in the adult is rare and its rupture is fatal. A 75-year-old man presented with congestive heart failure that suddenly occurred with a continuous murmur. Angiography showed a left-to-right shunt through a large thrombosed aneurysm of the ductus diverticulum (6 cm), and the pulmonary-to-systemic flow ratio was 2.6. Patch closure of the orifice (3x4 cm) of the aneurysm and repair of the perforated pulmonary artery were done emergently under hypothermic cardiopulmonary bypass with selective cerebral perfusion. He recovered uneventfully. Early recognition and early intervention should be indicated in this otherwise fatal condition.

Aged↗
PubMed1998

Appearance of nephrotic syndrome following interferon-alpha therapy in a patient with hepatitis B virus and hepatitis C virus coinfection.

A 59-year-old woman with hepatitis B surface antigen (HBsAg) and hepatitis C viral (HCV) antibody presented with proteinuria and hematuria. The patient was treated with interferon-alpha (INF-alpha) because plasma aminotransferase levels had been elevated and a liver biopsy had showed chronic active hepatitis. Her urinary protein excretion decreased as liver function normalized and her serum HCV-RNA was negative during treatment. Eleven weeks after completion of INF-alpha treatment, she suddenly presented with nephrotic-range proteinuria, although an improvement in the hepatic function was maintained. Renal pathologic findings were consistent with membranous glomerulonephritis (MGN), and HBsAg was detected in the glomeruli but not HCV. After treatment with prednisolone, her 24-hour protein excretion was below 0.7 g/day. To our knowledge this is the first report on hepatitis B virus MGN with nephrotic syndrome following IFN-alpha therapy for HCV. This suggests that treatment with INF-alpha might affect the immune processes and may be associated with the pathogenic mechanism in this patient.

Anti-Inflammatory Agents↗
PubMed1998

A rat model of chemical-induced polycystic kidney disease with multistage tumors.

Diphenylthiazole (DPT) induces polycystic kidney disease in the rat which serves as a model of human acquired cystic disease of the kidney. However, DPT administration alone does not produce neoplastic changes in renal cysts. We examined the effect of N-nitrosomorpholine (NNM), a carcinogen, in rats bearing DPT-induced renal cysts. Forty Sprague-Dawley rats were divided into four groups: DPT/NNM, DPT, NNM, and nontreated groups. DPT was administered throughout the experimental period, and NNM was given from weeks 4 to 7 after the start of the experiment. The rats were sampled from weeks 39 to 48, and histopathological examinations of the excised kidneys were performed. Multiple cystic changes were observed in all the DPT-treated rats in both DPT and DPT/NNM groups which were absent in almost all other rats. Solid adenomatous lesions were observed in the NNM-treated rats: in 7 of 9 and in 3 of 10 rats in the DPT/NNM and NNM groups, respectively. Cystic adenomatous lesions were found in 4 of 9 rats in the DPT/NNM group exclusively and not in the other groups. Combined DPT and NNM administration to rats produced an animal model showing neoplastic changes in renal cysts resembling microscopically renal cancer lesions in human acquired cystic disease of the kidney (on hematoxylin and eosin staining).

Animals↗
PubMed1998

Role of daunorubicin in the induction therapy for adult acute myeloid leukemia.

PURPOSE: To evaluate the relationship of total-dose of daunorubicin (DNR) to the induction therapy and treatment outcome, we have administered individualized doses of DNR during induction treatment to patients with acute myelogenous leukemia (AML). PATIENTS AND METHODS: Ninety-two previously untreated adult patients with AML who entered our hospital were analyzed for the dose of DNR required to achieve complete remission (CR), the CR rate, disease-free survival (DFS), and overall survival (OS). Induction therapy consisted of DNR 40 mg/m2 daily intravenously from day 1 until the marrow was hypoplastic, cytarabine (Ara-C), prednisolone (PRD), and/or 6-thioguanine (6-TG). RESULTS: Eighty-three of 92 patients with adult AML were assessable for this study. Sixty-three (76%) patients achieved CR. Fifty-two of 63 CR patients achieved the CR in the first course of induction therapy, and 11 patients required the second course of induction therapy. The 5-year and 10-year DFS rates were 31.2% and 5-year and 10-year OS rates were 45.1% and 42.3%, respectively. The median total dose of DNR in the induction therapy was 280 mg/m2 (120 to 480 mg/m2). DNR dose did not influence the response to therapy and was not influenced by the initial WBC count or French-American-British (FAB) system classification. CONCLUSION: These results indicated that when the dose was linked to observed tumor response, the optimal dose of DNR in the induction therapy was approximately 280 mg/m2 (40 mg/m2 for 7 days), which is greater than the conventional dose of 40 to 60 mg/m2 for 3 days.

Adolescent↗
PubMed1998

Cell cycle of myocytes of cardiac and skeletal muscle in mitochondrial myopathy.

Patients who have mitochondrial myopathy can present with specific pathological conditions (eg, diabetes mellitus and deafness). A 36-year-old woman presented with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). An investigation was conducted into whether the abnormalitiy of mitochondrial DNA (a T to C transition at position 3271 in the mitochondrial tRNA [Leu(UUR)] gene) influences nuclear DNA synthesis by cells in the heart, skeletal muscles, and brain. Myocardium, skeletal muscle, and brain tissues were stained with hematoxylin-eosin, and Masson trichrome for histopathology. Target nuclei taken from the myocardial and skeletal muscles and brain tissue were purified after removing debris by the modified Hedley method. These nuclei were stained with propidium iodide (PI) for analysis by flow cytometry. The number of nuclei in the G2M phase was bigger in myocytes of MELAS than in normal myocytes (Control) (MELAS myocyte: Control myocyte=24.9+/-7.3: 6.1+/-1.6%, p<0.005), but there was no significant increase in the G2M phase in brain tissue. The G1 phase was far more reduced in MELAS myocytes and skeletal muscle than in Controls (MELAS myocyte: Control myocyte=65.8+/-9.1: 88.0+/-3.2%, p<0.005; MELAS skeletal muscle: Control skeletal muscle=85.1+/-2.2: 90.1+/-3.2%, p<0.05), while there was no significant decrease of nuclei in the G1 phase in brain tissue. Increased amount of nuclei in the G2M phase in cardiac myocytes and skeletal muscle cells compared with that in neurons might depend on the capacity for proliferation and differentiation of these cells as compared with brain tissue. It was concluded that the mitochondrial DNA mutation (3271T-to-C) of MELAS may influence the nuclear DNA synthesis of cells in various tissues depending on their level of mitotic activity.

Adult↗
PubMed1998

Effects of voglibose on glycemic excursions, insulin secretion, and insulin sensitivity in non-insulin-treated NIDDM patients.

OBJECTIVE: To investigate the effects of voglibose, an alpha-glucosidase inhibitor, on daily glycemic excursions, insulin secretion, and insulin sensitivity in non-insulin-treated NIDDM patients. RESEARCH DESIGN AND METHODS: An open prospective study was conducted in 27 NIDDM patients receiving diet therapy alone or treatment with a sulfonylurea drug. Of the study subjects, 14 patients were treated with voglibose; the remaining 13 patients served as the control group. The metabolic parameters were evaluated before treatment and at week 4 of treatment as follows: glycemic excursions by M-value and 1,5-anhydro-D-glucitol (1,5-AG), insulin secretion by area under the curve of daily serum insulin (AUCinsulin), and insulin sensitivity by the K index of the insulin tolerance test (KITT). RESULTS: After the study treatment, HbA1c and plasma glucose in the patients who had received voglibose were comparable to those of patients in the control group. M-value was lower in the patients treated with voglibose than in the control subjects (5.7 +/- 0.9 vs. 9.8 +/- 1.2, P < 0.05). 1,5-AG was higher in the patients treated with voglibose than in the control subjects (12.2 +/- 1.0 vs. 8.2 +/- 0.7 micrograms/ml, P < 0.01). A statistically significant increase in AUCinsulin occurred after treatment with voglibose (2,223.5 +/- 390.6 to 1,546.7 +/- 303.4 pmol.l-1.h, P < 0.05), but no change occurred in the control group (2,364.5 +/- 315.4 to 2,464.2 +/- 269.3 pmol.l-1.h, P = 0.60). Insulin sensitivity (KITT) was improved to a statistically significant level in both the patients treated with voglibose and the patients in the control group. KITT in the patients after voglibose treatment was comparable to that of the control group (3.18 +/- 0.30 vs. 3.21 +/- 0.23%/min, P = 0.94). CONCLUSIONS: The results suggest that voglibose lowers the daily glycemic excursions and inhibits overwork of the pancreatic beta-cells but has little effect on insulin sensitivity in NIDDM patients.

Blood Glucose↗
PubMed1998

Antimalarial activity of radicicol, heptelidic acid and other fungal metabolites.

In the course of our screening program for artemisinin-like antimalarial compounds from microorganisms, seven fungal metabolites such as radicicol and heptelidic acid were identified as active compounds. Some of them exhibited antimalarial activity in vitro against the human malaria parasite Plasmodium falciparum to the extent of approximately 1/10 as potent as artemisinin. Radicicol was moderately active in vivo against Plasmodium berghei in mice.

Animals↗
PubMed1998

[An evaluation of limited operation for primary lung cancer].

The availability of a limited operation for the treatment of primary lung cancer was discussed on 50 cases underwent either partial resection or segmentectomy in our institute. Limited operation cases performed for poor risk groups and recurrent cases of lung cancer got satisfactory results for both functional state and prognosis. The availability of a limited operation as a positive operation is a subject in the future.

Adenocarcinoma↗
PubMed1998

[Primary cardiac non-Hodgkin's lymphoma].

A 69-year-old man who initially presented with lumbago developed heart failure during an MRI scan on the day of admission. A chest X-ray showed cardiomegaly and bilateral pleural effusion. Echocardiogram and computed tomography (CT) scan of the chest revealed a large tumor mass encompassing the heart with much pericardial effusion was demonstrated. The cytology of the effusion obtained by pericardiocentesis was consistent with non-Hodgkin's lymphoma, diffuse large B cell type. As CT scans of the abdomen and pelvis were negative, he was considered to have primary cardiac lymphoma. Although he responded remarkably to therapy with vincristine, cyclophosphamide and prednisolone and, he developed acute respiratory failure on the seventh month after admission. Although incidence of primary cardiac lymphoma is very low, it is necessary to investigate the mechanism of this disease in order to establish appropriate diagnostic and therapeutic approaches.

Aged↗
PubMed1998

Infrequent expression of p21 is related to altered p53 protein in pancreatic carcinoma.

This study is designed to investigate the expression of p21 and its relation to altered p53 protein in pancreatic carcinoma (PC). Immunohistochemical staining of formalin-fixed, paraffin-embedded tissue sections of PC was performed using a monoclonal antibody against p21 (187), with a parallel examination of altered p53 protein. The expression of p21 was only found in 12 of 58 (20.7%) PCs and, moreover, was mainly restricted to the well-differentiated ductal epithelium. Sixty-four % (37 of 58) of PCs showed positive p53 staining, and this change was significantly related to the absence of p21 expression (P < 0.01). In a subgroup, the proportion of the undetectable p21 expression and the expression of p53 were increased with increasing tumor grade but decreased with advancing clinical stage. The results of the present study suggest that the absence of p21 expression is very common in PCs and appears to relate to altered p53 protein. Moreover, the abnormalities involving the expression of p21 and p53 may play a more important role in the development than in the progression of this malignancy.

Adult↗
PubMed1998

[Radiotherapy in the treatment of brain metastasis from small cell lung carcinoma: study on appropriately controlled dose].

Fifty-two brain metastatic lesions occurring in 20 patients with small cell lung carcinoma (SCLC) were irradiated, and then the relationship between tumor size, dose and control was clinically and histopathologically studied. Lesions of 8 mm in diameter and those of 10 mm in diameter were determined to be controllable by irradiation at about 38 Gy and 42 Gy, respectively. According to size-dependent curative minimum doses, the lesions could be divided by the 10 Gy/ 5fr/wk method into controlled and non-controlled groups with the curve expressed as dose (Gy) = 15.27 log10 [tumor volume (mm3)] +0.6. Based on these results, tumors of 2 mm and 3 mm in diameter were estimated to be controllable at 14 and 20 Gy, respectively. Thus prophylactic cranial irradiation (PCI) in the treatment of SCLC was thought to be not always necessary if early treatment of small metastatic lesions, detected by Gd-DTPA-enhanced MRI could be achieved. The optimal interval between follow-up examinations was thought to be 1 month during the first two years after the diagnosis of SCLC, and then 3 months after that. In addition, the omission of PCI can save many patients who do not actually require PCI from suffering its adverse effects.

Aged↗
PubMed1998

The side-effects of ciclosporine-A and tacrolimus.

Ciclosporine-A (CSA) has been in clinical use as an immunosuppressive drug in transplant recipients for over a decade. Unfortunately, CSA also has major side-effects (including nephrotoxic ones). In an attempt to find safer agents, tacrolimus (TAC) has been introduced recently. Despite major differences in the chemical structure, TAC and CSA seem to have many effects in common. This phenomenon can be explained by the inhibition of the calcineurin pathway characteristic for both drugs. The aim of our brief review was to compare personal observations regarding side-effects encountered under CSA or TAC therapy with data reported previously. We found that the profile of side-effects both under CSA and TAC was nearly identical. In particular, morphologic changes associated with toxic drug effects in the kidney were indistinguishable from one another, i.e. tubular lesions, arteriolopathy, HUS-like changes in glomeruli and vessels. The prevalence of defined nephrotoxic lesions was very similar. Some differences were found regarding the prevalence of clinical side effects. Hypertension, hypertrichosis and gingival hyperplasia were less pronounced in the TAC group and an elevated blood glucose level in the CSA group. We conclude that TAC and CSA are closely related immunosuppressive drugs with regard to adverse effects.

Cyclosporine↗
PubMed1998

[Efficacy of microwave coagulation therapy (MCT) in patients with liver tumors].

We evaluated the efficacy of microwave coagulation therapy (MCT) in 84 patients with hepatocellular carcinomas (HCC) and 40 with metastatic liver tumors (MLT). The response rates calculated with diagnostic imaging were 92% in HCC and 80% in MLT. The regional recurrence rates were relatively higher in patients with MLT (33%) than in HCC (14%). The average surgical margin in operative MCT group was 11 mm. The cumulative survival rates at three and five years were 63% and 38% in HCC and 43% and 33% in MLT, respectively. The complications were similarly encountered in HCC and MLT (12% versus 13%). When these observations are taken together, MCT is a radical and safe locoregional therapy which can keep an adequate surgical margin and assure long survival.

Adolescent↗
PubMed1998

[A clinicopathological study of recurrent IgA nephropathy following renal transplantation].

The present study was conducted to examine the clinicopathological features of recurrent IgA nephropathy (IgAN) following renal transplantation. Serial renal biopsies were performed regularly at 0-hour, 1-hour and 2-hours, and 39 episode biopsies were carried out when patients had increased serum creatinine levels and proteinuria. In 49 renal allograft recipients with IgAN, 12 patients were proved to be recurrent IgAN (24.5%). There was a significantly increased five- and ten-year risk of graft loss in the renal allograft recipients with biopsy-proved recurrent IgAN. Graft survival in 49 renal allograft recipients with IgAN was worse (68.8% at 5 years and 40.4% at 10 years) than that in 997 whole transplants (80.7% at 5 years, and 67.7% at 10 years). We found significant differences in the prevalence of HLA-DR4 (66.7%) and BW35 (25%) in the renal allograft recipients with recurrent IgAN when compared with normal healthy subjects. The renal allograft recipients with recurrent IgAN had a high incidence of proteinuria (8/12), hypertension (9/12) and renal dysfunction of less than 50 ml/min (7/12). Mean hemodialysis duration before renal transplantation in recurrent IgAN transplants was 12.5 months, which was shorter than in those without recurrent IgAN. Histopathological studies revealed that renal lesions due to IgAN frequently appeared in the renal allograft recipients with recurrent IgAN. Taken together, these findings suggest that donor-recipient matching may be carefully reconsidered, and recurrent IgAN after renal transplantation must be treated with effective immunosuppressive therapy.

Adult↗