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Biomedical subjects

T Ohara

Publications and source records attributed to T Ohara.

At least 127 records · Page 7Linked to original sources
PubMed1994

Fractional mean transit time in transplanted kidneys studied by technetium-99m-DTPA: comparison of clinical and biopsy findings.

UNLABELLED: To determine the usefulness of fractional mean transit time (MTT) in the differential diagnosis of postrenal transplant complications, 99mTc-DTPA was used to evaluate differences in MTT between the outer zone (cortical nephron) and middle zone (juxtamedullary nephron, calcyces and cortical nephron) of the kidney. It is well known that acute rejection is characterized by delayed cortical transit time, whereas cortical nephron function is well maintained and juxtamedullary function is impaired after renal ischemia. METHODS: Technetium-99m-DTPA fractional MTT was determined by deconvolution analysis of 89 renograms obtained within 5 days of the date of kidney graft biopsy and evaluation. RESULTS: Outer zone MTT was significantly shorter than middle zone MTT in normals (2.7 +/- 0.4 versus 3.0 +/- 0.6 min, n = 22, p < 0.001), acute tubular necrosis (3.4 +/- 1.1 versus 3.6 +/- 1.4 min, n = 19, p < 0.01), chronic rejection (3.9 +/- 1.5 versus 5.0 +/- 2.3 min, n = 14, p < 0.001) and obstruction (4.1 +/- 0.6 versus 8.9 +/- 3.4 min, n = 13, p < 0.001). In contrast, outer zone MTT was significantly longer than middle zone MTT in acute rejection (4.8 +/- 3.2 versus 4.2 +/- 2.5 min, n = 21, p < 0.05). CONCLUSION: Fractional MTT was demonstrated to be useful in differentiating acute rejection and ATN in transplanted kidneys.

Adolescent↗
PubMed1993

Induction of renal pelvic carcinoma by phenacetin in hydronephrosis-bearing rats of the SD/cShi strain.

Carcinogenicity of phenacetin (PH) to the urinary tract was tested with the use of spontaneously hydronephrosis-bearing rats. In Experiment 1, 55 SD/cShi male rats were fed with 2% PH-containing diet for 85 weeks, and 32 SD/cShi male rats fed basal diet for 85 weeks served as controls. Forty-three of 53 rats fed with PH had renal pelvic carcinoma with lung metastases in three. The mean induction time was 78 weeks. Ureteral carcinoma and urinary bladder carcinoma were observed in 2 and 6 of 53 rats given PH, respectively. No urinary tract carcinoma was found in control animals. In Experiment 2, early lesions of the kidney affected by PH were also evaluated with the use of SD/cShi and Sprague-Dawley (SD) rats. Two groups of animals containing 6 SD/cShi or 6 SD male rats per group were fed 2% PH-containing diet for 8 weeks. Control animals containing 6 SD/cShi rats or 6 SD rats were fed basal diet for 8 weeks. Simple hyperplasia was found in 5 of 6 SD/cShi rats given PH and 2 of 6 SD/cShi control rats. Papillary necrosis was seen in 4 of 6 SD/cShi and 2 of 6 SD rats given PH. SD/cShi rats, especially those treated with PH, showed higher but not significant 5-bromo-2'-deoxyuridine labeling indices in the covering epithelium of the renal pelvis and papillae. In this short term experiment PH and its metabolites, N-hydroxyphenacetin and N-acetyl-p-aminophenol, were measured in urine and plasma by using high performance liquid chromatography. Significantly higher PH and slightly higher metabolites were detected in urine and plasma of SD/cShi rats compared to SD rats. These results indicated that the renal pelvis of SD/cShi rats had more sensitivity to PH carcinogenicity. This paper provides experimental proof of PH carcinogenicity toward the renal pelvis in an animal model.

Animals↗
PubMed1993

Giant benign mesenchymoma of the mediastinum causing superior vena cava syndrome: report of a case.

The surgical resection of a giant primary mediastinal mesenchymoma causing superior vena cava syndrome is herein described. A 53-year-old man was admitted to the hospital complaining of severe dyspnea. A chest roentgenogram showed a large mediastinal mass shadow compressing the superior vena cava. At surgery, a yellow tumor measuring 27 x 25 x 12 cm and weighing 3,620 g was resected. The histological diagnosis was benign mesenchymoma. The patient's postoperative course was uneventful with a successful resolution of his superior vena cava syndrome.

Humans↗
PubMed1993

Thyroid hormone stimulates Na(+)-K(+)-ATPase gene expression in cultured rat mesangial cells.

Thyroid hormone 3,3',5-triiodothyronine (T3) is an important regulator of Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase) activity in a variety of mammalian target tissues. In the present study, we examined the expression of Na(+)-K(+)-ATPase alpha- and beta-subunit mRNAs by T3 in cultured rat mesangial cells. Northern blot analysis of total RNA isolated from cultured rat mesangial cells revealed the expression of mRNAs encoding Na(+)-K(+)-ATPase alpha 1- and beta 1-subunits; mRNAs encoding alpha 2- and alpha 3-subunits were undetectable. Exposure of mesangial cells to T3 (10(-8) M) caused a threefold increase in the alpha 1-mRNA expression, which was first detected at 6 h and sustained for at least 48 h. The beta 1-mRNA expression was gradually increased by T3, with a maximum fourfold elevation at 48 h. The 50% effective concentration (EC50) for the alpha 1- and beta 1-mRNA induction by T3 was approximately 10(-10) M. The half-life of alpha 1-mRNA analyzed by actinomycin D chase was approximately 3 h and was not affected by T3. The augmented alpha 1-mRNA expression by T3 was associated with a 2.4-fold increase in the alpha 1-subunit protein accumulation and a 1.6-fold increase in Na(+)-K(+)-ATPase activity. These data suggest that thyroid hormone stimulates Na(+)-K(+)-ATPase gene expression, protein accumulation, and enzyme activity in rat mesangial cells.

Animals↗
PubMed1993

Effect of prostaglandins on renal function in uninephrectomized humans.

We examined the effects of unilateral nephrectomy (UN) and administration of indomethacin in 15 healthy humans. Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), urine flow, sodium and potassium excretions, urinary excretion rate of prostaglandin E2 (PGE2) and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) in the remaining kidney were all significantly (p < 0.01) increased 10 days after UN. Indomethacin administered at 75 mg/day for 3 days abolished the increase in GFR, ERPF and sodium excretion with reduced urinary excretion rate of PGE2 and 6-keto PGF1 alpha but not the increase in urine flow and potassium excretion. These findings suggest that renal prostaglandins may play a role in renal functional adaptation following UN.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

[Long-term follow-up results of stage III and IV thymomas and thymic carcinomas invading the great veins].

A series of 24 patients with stage III and IV thymomas and thymic carcinomas were reviewed with respect to the invasiveness of the superior vena cava (SVC) and brachiocephalic veins (BCV). Masaoka staging revealed stage III disease in 14 patients and stage IV in 10. Follow-up ranged from 3 months to 12 years and 10 months. In 9 patients with stage III disease involving the great veins, 6 patients underwent total resection, 2 subtotal resection, and one exploratory thoracotomy. Reconstruction of SVC was done in 2 patients and of left BCV in 7 and angioplasty of SVC in one. Although there were 4 tumor deaths and one myasthenic death, 4 patients were alive and tumor free. The longest survival after total resection with SVC replacement was 11 years and 7 months. In 3 patients with stage IV disease invading the great veins, 2 patients underwent partial resection and one received radiotherapy alone. Although 2 patients died of generalized metastases and respiratory failure respectively, one remained alive 2 years and 2 months with carcinoma. Although long-term survivors were obtained in the patients with adventitial involvement, prognosis was poor in the patients with intimal invasion.

Adolescent↗
PubMed1993

[Growth and serial changes of bone calcium content after renal transplantation in childhood].

We evaluated metacarpal index (MCI) and bone mineral content (BMC) of right 2nd metacarpal bone X-ray films using the microdensitometer technique in 12 pediatric and 32 adult renal transplant (Tx) recipients. Grafts were well functioning for more than 1 year in all adults (serum creatinine < or = 2.0 mg/dl) and in 9 of the children (serum creatinine < or = 1.2 mg/dl). Immunosuppression consisted of cyclosporin (CyA), methylprednisolone (MPL), mizoribine and anti-lymphocyte globulin for all children. 18 of the adults were given CyA and 14 were given conventional immunosuppression. BMC was found to be increased in both children with good renal function and in adults. MCI was improved in 2 children with good renal function and in 2 adults using CyA. Immunosuppression of CyA and low dose MPL had an improving effect on renal osteodystrophy. Alternate-day MPL dosage was between 1, 6 and 7.3 mg/m2/day (mean 3, 6 mg/m2/day) in the 9 children with good renal function. Bone age of the children was seen to be developed in accordance with calendar age. Growth velocity of the 9 children with good renal function was better than the mean level of normal children. However, growth velocity at 3 years after Tx declined slightly, compared with that within 2 years. Similarly, somatomedin C was above the normal range within 2 years after Tx. Thus, bone metabolism after Tx may have been influenced by serial changes of somatomedin C.

Adolescent↗
PubMed1992

Na+/K(+)-ATPase activity and its alpha II subunit gene expression in rat skeletal muscle: influence of diabetes, fasting, and refeeding.

We have examined the effects of diabetes, fasting, and refeeding on Na+/K(+)-adenosine triphosphatase (ATPase) activity and its catalytic alpha II subunit gene expression in skeletal muscle. Two hypoinsulinemic states, streptozotocin-induced diabetes and 48-hour fasting caused a significant decrease (P less than .05) in skeletal muscle Na+/K(+)-ATPase activity and a marked increase (P less than .01) in the levels of alpha II subunit mRNA. A decrease in enzyme activity was observed on the 2nd and the 14th day of diabetes, whereas an increase in alpha II mRNA levels was found only on the 14th day. The levels of alpha I mRNA were not affected, while the levels of mRNA of the structural beta subunit were decreased on the 14th day of diabetes. Correction of hyperglycemia with insulin restored enzyme activity and alpha II isoform mRNA levels toward normal in diabetic animals. Refeeding for 48 or 72 hours restored these parameters to normal in skeletal muscle of previously fasting rats. These observations suggest that a decrease in muscle Na+/K(+)-ATPase activity may lead to a compensatory increase in its alpha II subunit gene expression. The levels of insulin and not of glycemia appear to be critical in modulating Na+/K(+)-ATPase activity and gene expression.

Animals↗
PubMed1992

Stimulation of Na+/H+ exchange induced by angiotensin II in cultured rat vascular smooth muscle cells: role of Ca2+ and C-kinase.

Changes in cytosolic calcium concentration ([Ca2+]i) have been implicated in the regulation of intracellular pH (pHi) in several cell types. In the present study we investigated the regulatory mechanism of Na+/H+ exchange induced by angiotensin II (AII) in cultured rat vascular smooth muscle cells (VSMCs). Serially passaged VSMCs from Sprague-Dawley rat thoracic aorta were grown on coverslips and loaded with the pH-sensitive fluorescent indicator 2',7'-bis-(carboxyethyl)-5,6-carboxyfluorescein (BCECF). In HCO(3-)-free Ringer solution, pH 7.40, the resting pHi was 7.21 +/- 0.02 (n = 21). A biphasic response was seen after exposure of these cells to AII: an initial transient a acidification, followed by sustained alkalization. The magnitude of alkalization was dose-dependent. AII-mediated acidification was completely inhibited by [Sar1-IIe5-Gly8]AII, but amiloride had no effect. In contrast, the alkalization induced by AII was abolished by both amiloride and Na(+)-free medium. In Ca(2+)-free medium, the AII-induced alkalization was partially blocked and verapamil also caused partial inhibition. Since AII activates phospholipase C in VSMCs, we examined whether AII would increase Na+/H+ exchange by activation of protein kinase C. An inhibitor of protein kinase C, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), partially inhibited the alkalization induced by AII. These results indicate that AII stimulates cytoplasmic alkalization via an amiloride-sensitive Na+/H+ exchange system in cultured rat VSMCs, and that this AII-stimulated Na+/H+ exchange is mediated by Ca(2+)-dependent and protein kinase C-dependent mechanisms.

Amiloride↗
PubMed1992

Effect of omeprazole on ascorbate free radical formation.

In order to study the effect of omeprazole on the K/[H+] value of ascorbic acid (K = the ascorbic acid-ascorbic free radical equilibrium constant), changes of the concentration of ascorbate free radical in guinea pig sera were examined after intraperitoneal administration of omeprazole. Furthermore, to see the in vitro effect of omeprazole on ascorbate free radical, changes were examined in ascorbate solutions after addition of omeprazole. It was found that the K/[H+] value in the serum increased significantly after administration of omeprazole and also that the drug amplified the electron spin resonance (ESR) signal intensity of ascorbate free radical in vitro. These results suggested that omeprazole acts like oxygen radicals.

Animals↗
PubMed1992

[Effect of gastric mucosal denervation on gastric carcinogenesis].

Numerous nerve fibers containing various neuropeptides are found in gastric mucosa. They play an important role not only in regulation of gastric secretion, motility and microcirculation but also in regeneration and differentiation of gastric mucosa. These nerve fibers are reduced in chronic atrophic gastritis which is considered a lesion closely related to carcinogenesis. We investigated the effect of gastric gastric mucosal denervation (vagotomy) on gastric carcinogenesis by using two experimental rat models in which chronic atrophic gastritis is induced by duodenogastric reflux. At first, following administration of MNNG, vagotomy with duodenogastric reflux enhanced gastric carcinogenesis compared to reflux only. At second, in the model of gastric remnant in which no carcinogenic agent was given, both B-I and B-II gastrectomy with vagotomy showed an increase of carcinoma and/or adenoma at the anastomotic site compared to those without vagotomy. Moreover, in vagotomized groups, there were an increase of labeling index of PCNA positive cells in gastric mucosa and a marked reduction of intramucosal neutral mucin in PAS-Alcian blue staining. These results indicate that the lack of gastric mucosal innervation not only induces the decrease of gastric mucosal cell function and cytoprotection but also enhances the increase of immature cell regeneration.

Animals↗
PubMed1992

Recombinant interleukin-6 inhibits the growth of rat mesangial cells in culture.

Murine recombinant interleukin-6 (IL-6) inhibited [3H]thymidine uptake by cultured rat mesangial cells in a dose-dependent manner in the presence of 0.5% fetal bovine serum (FBS). The inhibitory effect of IL-6 on the growth of mesangial cells was also confirmed by a change in cell numbers. In the presence of increased concentrations of FBS (5% or 10%), the effect of IL-6 was not prominent. IL-6 showed no effects on intracellular Ca2+ levels of mesangial cells. IL-6 gene expression was rapidly induced in the "quiescent" mesangial cells by exposure to 20% FBS. These observations support the premise that IL-6 is synthesized in mesangial cells and inhibits the growth of mesangial cells in an autocrine manner.

Animals↗
PubMed1992

[Clinical studies of patients with bladder cancers].

A clinical survey was performed on 185 cases of primary bladder cancer treated at our Department of Urology, between January, 1985 and December, 1989. Clinicopathological profiles of patients and survival rates according to these profiles were investigated. The patients were between 29 and 95 years old. The male to female ratio was 3.1 to 1. The cumulative survival rate after the first treatment was 73.3% and 71.5% at 3 and 5 years, respectively. Histologically, 17 cases were diagnosed as transitional cell carcinoma G1, 69 cases as G2 and 69 cases as G3. 5 cases were diagnosed as stage pTis, 6 cases as pTa, 41 cases as pT1, 15 cases as pT2, 9 cases as pT3a, 14 cases as pT3b and 6 cases as pT4. Stage, grade, size and type of tumors reflected the prognosis well. Significant differences were observed between the survival rates of the patients with grade G2 and grade G3, and the patients with stage T1 and stage T2. Although low-grade low-stage tumors recurred in 44% of the patients. The pathological stage showed a good relation to the grade. In particular, none of the G1 bladder tumors had muscle invasion in our series.

Adult↗
PubMed1992

[A case of double mediastinal tumors].

We reported a pediatric case of double mediastinal tumors. A 7-year-old girl was admitted to our hospital as the abnormal shadows were pointed out on her chest x-ray film. CT scan and MRI suggested the existence of double tumors located at the anterior and middle mediastinum. Both tumors and thymus were removed. Histological diagnosis of one tumor was teratoma of the anterior mediastinum and another was bronchogenic cyst of the middle mediastinum respectively. Pertinent literatures were reviewed.

Bronchogenic Cyst↗