Search PubMed⌕ Search

Biomedical subjects

T Okamoto

Publications and source records attributed to T Okamoto.

At least 127 records · Page 7Linked to original sources
PubMed2001

Performance of the basal aldosterone to renin ratio and of the renin stimulation test by furosemide and upright posture in screening for aldosterone-producing adenoma in low renin hypertensives.

An aldosterone-producing adenoma causes surgically correctable hypertension. Screening tests should be assessed for their accuracy and ability to detect aldosterone-producing adenoma in an appropriate population. This study aims to validate the accuracy and efficacy of the basal plasma aldosterone concentration (picomoles per liter) to PRA (nanograms per liter/sec) ratio and of combined stimulation of PRA by the furosemide and upright posture test in screening for aldosterone-producing adenoma in hypertensives with PRA less than 0.28 ng/liter.sec (1 ng/ml.h). Thirty-five aldosterone-producing adenoma and 79 nonaldosterone-producing adenoma patients were retrospectively selected from among 159 patients examined with the furosemide and upright posture test between 1989 and 1999. Selection criteria were based on blood pressure, PRA, and plasma aldosterone concentration. Diagnosis was based on surgical outcome, computed tomography scans with adrenal scintigraphy, or venous sampling. The accuracy and efficacy of basal (aldosterone/PRA ratio) and dynamic (postfurosemide and upright posture PRA) screening tests were assessed based on test sensitivity, specificity, likelihood ratio, and receiver operating characteristics. At a cut-off value of 3,200, the aldosterone/PRA ratio had a high sensitivity of 1.0 and a low specificity of 0.61. The importance was strengthened by using a multilevel likelihood ratio, i.e. positive (aldosterone/PRA ratio >10,000), negative (aldosterone/PRA ratio <3,200), and neutral (intermediate aldosterone/PRA ratio) levels. Patients with a positive level had a likelihood ratio of 7.1 and were likely to have an aldosterone-producing adenoma. The aldosterone/PRA ratio enclosed a larger area under the receiver operating characteristics curve (0.905) than did postfurosemide and upright posture PRA (0.826). In conclusion, the plasma aldosterone concentration to PRA ratio is an effective screening and diagnostic test when a triple level likelihood ratio is applied. The furosemide and upright posture test did not raise the posttest probability over that obtained using the aldosterone/PRA ratio.

Adenoma↗
PubMed2001

Inhibition of concanavalin A-induced mice hepatitis by coumarin derivatives.

The effects of coumarin derivatives, osthole, imperatorin, Pd-Ia, Pd-II and Pd-III, on mice concanavalin A (Con A) (0.2 mg/mouse, i.v.)-induced hepatitis were studied. At the dose of 200 mg/kg (i.p.), these coumarins inhibited more than 90% of the Con A-induced elevation of plasma alanine aminotransferase activity, but glycyrrhizin (200 mg/kg, i.p.) caused only 45% inhibition. At the dose of 100 mg/kg (i.p.), osthole produced the strongest inhibition among these coumarins. The inhibitory activity of osthole is lost when its 7-methoxy group is replaced by a 7-hydroxy group to form osthenol. The present results showed that coumarin derivatives inhibited Con A-induced hepatitis, with osthole being the most inhibitory.

Alanine Transaminase↗
PubMed2001

Hepatoprotective drugs for the treatment of virus-induced chronic hepatitis: from hypercarcinogenic state to hypocarcinogenic state.

Interferon (IFN)-based therapy is a standard treatment for chronic hepatitis caused by hepatitis C virus (HCV) infection. This treatment is effective in approximately 30-40% of the patients and using ribavirin in combination with IFN increases the rate of sustained virologic clearance. For the remaining patients, glycyrrhizin is often used. Glycyrrhizin is known to prevent the development of hepatocellular carcinoma (HCC), but glycyrrhizin is usually administered intravenously. Drugs that are effective by oral administration are convenient for patients for long-term administration, and development of more effective drugs than glycyrrhizin is preferable. However, studies on drugs for the treatment of hepatitis are not actively conducted, and promotion of the study of drugs in this area is encouraging. For that reason, we show our approach to study drugs for the treatment of hepatitis. We analyzed the effect of glycyrrhizin on hepatitis as a standard chemical using the mouse liver injury model. Based on this, we screened drugs and found that a coumarin derivative seems to be one of model chemicals for the treatment of hepatitis.

Alanine Transaminase↗
PubMed2001

Chemistry of zerumbone. 2. Regulation of ring bond cleavage and unique antibacterial activities of zerumbone derivatives.

Further investigation of the chemistry of the eleven-membered cyclic sesquiterpene, zerumbone, the major component of the wild ginger, Zingiber zerumbet Smith, has revealed a new selective epoxidation process, a further example of a novel Favorskii-initiated double ring contraction, and a regiospecific fragmentation of zerumbone dibromide derivatives. Several zerumbone derivatives were found to be selective inhibitors of the growth of gram-positive bacteria.

Anti-Bacterial Agents↗
PubMed2001

Antibacterial agents that inhibit histidine protein kinase YycG of Bacillus subtilis.

We demonstrated in vitro that YycG-YycF of Bacillus subtilis constitutes a two-component system and shows a specificity of the sensor protein for the cognate phosphorylation partner. Based on inhibition of such an autophosphorylation of YycG, we searched imidazole and zerumbone derivatives to identify the antibacterial agents such as NH125, NH126, NH127, and NH0891.

Anti-Bacterial Agents↗
PubMed2001

Human chorionic gonadotropin (hCG) beta-core fragment is produced by degradation of hCG or free hCG beta in gestational trophoblastic tumors: a possible marker for early detection of persistent postmolar gestational trophoblastic disease.

The present study was undertaken to investigate whether human chorionic gonadotropin (hCG) beta-core fragment (hCG beta cf) was directly produced by gestational trophoblastic tumors. Immunoreactivity of hCG beta cf was demonstrated in the extracts as well as in the culture media of hydatidiform mole tissues. It was also present in the extracts of choriocarcinoma tissues, and its molar concentration exceeded that of intact hCG. The presence of hCG beta cf was then confirmed by gel chromatography and Western blot analysis. Immunohistochemistry showed localization of hCG beta cf immunoreactivity to the syncytiotrophoblasts and scattered cells in the stroma of mole tissue, and to syncytiotrophoblastic cells in choriocarcinoma. Immunoreactivity of hCG beta cf was also detected in the sera of the patients with gestational trophoblastic disease, although the hCG beta cf/hCG ratio was less than one hundredth of that in the tissue extracts. Serial measurement of serum hCG beta cf levels after mole evacuation showed that they declined much more rapidly than those of hCG and became undetectable in the patients with subsequent spontaneous resolution, while hCG beta cf remained or became detectable before the rise of hCG was observed in the patients with subsequent persistent trophoblastic disease. Taken together, these results suggest that hCG beta cf is directly produced by gestational trophoblastic tumors, and monitoring of hCG beta cf in the serum after mole evacuation may be useful for early prediction of subsequent development of postmolar persistent trophoblastic disease.

Animals↗
PubMed2001

Malignant fibrous histiocytoma of soft tissue producing granulocyte colony-stimulating factor.

We treated a rare case of malignant fibrous histiocytoma (MFH) of soft tissue that produced granulocyte colony-stimulating factor (G-CSF). The patient, an 80-year-old woman, was admitted because of a feeling of abdominal fullness and leg edema. An elastic, hard, tender tumor was palpated in the right thigh. Histopathological examinations of the tumor revealed atypical and prominent pleomorphic spindle-shaped cells with funicular arrangement, which were compatible with the diagnosis of MFH. Prominent leukocytosis (up to 84,300/microl), a high serum G-CSF concentration (82 pg/ml) and positive immunohistochemical staining of the tumor tissue for G-CSF indicated that G-CSF was produced by the MFH.

Aged↗
PubMed2001

Endovascular trapping of giant serpentine aneurysms by using Guglielmi detachable coils: successful reduction of mass effect. Report of two cases.

Giant serpentine aneurysms (GSAs) are defined as partially thrombosed giant aneurysms with persistent serpentine vascular channels. Surgical management of these rare lesions is difficult because of their large size, complex structure, and unique hemodynamics. The authors report two cases of patients harboring GSAs with mass effect, which were managed effectively with endovascular treatment. The first patient was a 48-year-old man who presented with left homonymous hemianopsia caused by a GSA involving the terminal portion of the right internal carotid artery. The second patient, a 10-year-old boy, presented with tetraparesis from compression of the cervicomedullary junction by a GSA of the right vertebral artery. In each case, after confirming collateral flow by temporarily occluding the proximal artery, the aneurysm was trapped by placement of Guglielmi detachable coils at the sites at which the serpentine channels entered and exited the aneurysm. The midportion of each channel was isolated completely without packing, to maximize resorption of the devascularized mass. Mass effect and clinical symptoms rapidly improved in both cases, with no associated morbidity. We recommend endovascular trapping as a safe and effective therapeutic option for GSAs.

Carotid Artery Diseases↗
PubMed2001

Zaltoprofen prevents carbon tetrachloride-induced reduction of body weight in rats.

Previously we reported carbon tetrachloride-induced body weight loss in rats as a new model of wasting disorders. The oral administration of a low dose of carbon tetrachloride to rats reduced the body weight and food intake at 24 h with a minimal effect on plasma alanine aminotransferase activity. Tumor necrosis factor-alpha, and cyclooxygenase-1 and -2 mRNA expression in the brain was not affected by carbon tetrachloride. Zaltoprofen, which is a non-steroidal anti-inflammatory drug, prevented the carbon tetrachloride-induced body weight decrease, without preventing the carbon tetrachloride-induced loss of food intake. The present results suggest the possible application of this drug for the treatment of wasting disorders.

Animals↗
PubMed2001

Development of anorexia in concanavalin A-induced hepatitis in mice.

Anorexia that develops in chronic hepatitis is associated with cytokine expression in the brain. Treatment of mice with concanavalin A (12.5 mg/kg, i.v.) elevated the plasma alanine aminotransferase activity at 8.5 h after treatment. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta mRNA expression was induced at 6 and 24 h after concanavalin A treatment in both the liver and brain. Treatment of mice with concanavalin A reduced the body weight at 24 h after treatment and this decreased body weight was accompanied by a decreased food intake. Glycyrrhizin (200 mg/kg, i.p.) inhibited the concanavalin A-induced elevation of plasma alanine aminotransferase activity, however, it did not inhibit the concanavalin A-induced decreased body weight. The present results indicate that treatment of mice with concanavalin A caused the development of anorexia and that this anorexia might develop independently of the induction of hepatitis.

Alanine Transaminase↗
PubMed2001

Inhibition of anti-Fas antibody-induced mice hepatitis by furocoumarin derivatives.

The effects of imperatorin and its synthetic derivative, Y355, on anti-Fas antibody-induced mice hepatitis were studied. Pretreatment of mice by intraperitoneal administration of imperatorine or Y355 at 30 mg/kg inhibited more than 80% of the anti-Fas antibody (150 microg/kg, i.v.)-induced elevation of plasma alanine aminotransferase activity. Furthermore, oral administration of imperatorin or Y355 at 100 mg/kg also had an inhibitory effect on anti-Fas antibody-induced hepatitis. Both compounds inhibited anti-Fas antibody (250 microg/kg)-induced caspase-1 and caspase-3 activities. The present results showed the inhibition of anti-Fas antibody-induced hepatitis by imperatorin and Y355, which might be a result of inhibition of caspase activities.

Alanine Transaminase↗
PubMed2001

Prevention of concanavalin A-induced mice hepatitis by molsidomine.

Molsidomine is effective in reducing portal hypertension in cirrhosis, but its effect on hepatitis is not known. In the present study, the effect of molsidomine on hepatitis was examined using mouse concanavalin A (Con A)-induced hepatitis and mouse anti-Fas antibody-induced hepatitis. Treatment of mice with Con A caused elevation of plasma alanine aminotransferase (ALT) at 8 and 24 h (n=4). Pretreatment of mice with molsidomine (3, 10, 30 and 100 mg/kg, i.p.) prevented Con A-induced hepatitis. Treatment of mice with anti-Fas antibody (150 microg/kg, i.v.) caused elevation of plasma ALT at 3.5 h. Pretreatment mice with molsidomine (10 mg/kg, i.p.) showed only 47% inhibition of anti-Fas antibody caused elevation of plasma ALT. The present results showed effectiveness of molsidomine in preventing Con A-induced mice hepatitis.

Alanine Transaminase↗
PubMed2001

NC-1500 prevents concanavalin A-induced mice hepatitis without affecting cytokine gene expression.

NC-1500 is a dihydropyridine type calcium channel blocker. The effect of NC-1500 on mice concanavalin A-induced hepatitis was examined. Treatment of mice with concanavalin A (Con A) caused elevation of plasma transaminase. Pretreatment of mice with NC-1500 (3, 10 and 30 mg/kg, p.o.) prevented this Con A-induced elevation of plasma transaminase. Treatment of mice with Con A induced tumor necrosis factor-alpha (TNF-alpha) mRNA expression in the liver. However, NC-1500 (30 mg/kg, p.o.) did not affect this Con A-induced TNF-alpha mRNA expression in the liver. The present results showed that NC-1500 inhibited Con A-induced hepatitis without affecting TNF-alpha mRNA expression in the liver.

Alanine Transaminase↗
PubMed2001

Zaltoprofen inhibits concanavalin A-induced decrease of body weight in mice.

Treatment of mice with concanavalin A (Con A) (12.5 mg/kg, i.v.) decreased the body weight at 24 h. This Con A-induced body weight decrease was accompanied by reduction in food and water intake. Zaltoprofen is a non-steroidal anti-inflammatory drug. The administration of Zaltoprofen (10 mg/kg) at 8 h after Con A treatment was found to inhibit the Con A-induced reduction in body weight. The food intake in mice treated with Con A plus Zaltoprofen (10 mg/kg) was four times greater than that in mice treated with only Con A. The present results showed inhibition of the Con A-induced body weight loss by Zaltoprofen and suggested its possible effectiveness for the treatment of "sickness behavior".

Animals↗
PubMed2001

Expression of the alpha1D subunit of the L-type voltage gated calcium channel in human liver.

Calcium channel blocker is useful for a variety of purposes and is effective for preventing hepatitis elicited by different inducers, suggesting its possible clinical application for treating hepatitis. The alpha1-subunit of the dihydropyridine-sensitive L-type calcium channel is a target of calcium channel blocker. For clinical application of calcium channel blocker, it is important to analyze the expression of the L-type calcium channel in the liver. However, the subtype of the L-type calcium channel alpha1-subunit expressed in the liver was not known. In the present study, the alpha1-subunit of the calcium channel expressed in human liver was systematically analyzed. The alpha1D subunit of the dihydropyridine-sensitive L-type voltage gated calcium channel is expressed relatively strongly in the liver and may play an important role in the liver.

Calcium Channels, L-Type↗
PubMed2001

Suppression of cytochrome P450 1A1 and 4A1 gene expression in renal carcinomas of TSC2 gene mutant (Eker) rats.

In the kidney, cytochrome P450 (CYP) is involved in arachidonic acid metabolism and the maintenance of homeostasis, but only scarce information is available as to how CYP expression is altered in rodent renal carcinomas (RCs). TSC2 gene mutant (Eker) rat RCs are an example of a Mendelian dominantly inherited predisposition to a specific cancer in an experimental animal. In the present study, the expression of CYP in Eker RCs was studied. In the normal kidney, CYP 1A1 and 4A1 mRNAs were expressed, but this expression was suppressed in spontaneously-induced Eker RCs and in cell line Lk9dL and Lk9dR. In Lk9dL and Lk9dR, Ah receptor nuclear translocator and haemoxygenase-1 mRNAs were expressed, but this expression was inconsistent in spontaneously-induced Eker RCs. The present results showed the suppression of CYP 1A1 and 4A1 mRNA expression in spontaneously-induced Eker RCs and this suppression indicates altered metabolic conditions in Eker RCs.

Animals↗
PubMed2001

Hydroxylapatite implants with or without collagen in the zygomatic arch of rats. Histological study.

The authors studied the behavior of calcium phosphate materials used as inlay implants into bone cavities prepared in the zygomatic arch of rats. Fifty male albino rats were divided into four groups as follows: group I-preparation of bone cavities which did not receive any implant material as controls; group II-implants of Interpore 200; group III-implants of experimental hydroxylapatite; group IV-implants of experimental hydroxylapatite combined with collagen. The animals were sacrificed after 5, 15, 30, 60 and 120 days and the specimens were submitted to histological analysis. Results showed that the experimental hydroxylapatite used in group III presented better osteogenic properties compared to the other materials. All tested materials were biocompatible, although group IV presented a more intense inflammatory response.

Animals↗