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Biomedical subjects

Y Takehara

Publications and source records attributed to Y Takehara.

At least 19 recordsLinked to original sources
PubMed1992

Case report: MR appearance of a retained surgical sponge.

A case of a retained surgical sponge found in the retroperitoneum is presented with findings on magnetic resonance (MR) imaging, computed tomography (CT), ultrasonography (US) and angiography. Among all the performed modalities, a characteristic internal structure of the gauze granuloma was best visualized on MR imaging. If no radio-opaque marker is seen on plain radiography or CT, the folded fabric inner structure visualized on T2-weighted images can be a most important clue to the correct diagnosis of this iatrogenic mass.

Female↗
PubMed1992

Reperfusion and irreversible myocardial injury: identification with a nonionic MR imaging contrast medium.

The potential of a new nonionic gadolinium complex--gadodiamide injection--to (a) allow distinction between reperfused and occlusive infarction and (b) enable differentiation between reperfused reversible and irreversible myocardial injury was investigated. Three groups of rats were used: 10 with reversibly reperfused myocardial injury, 10 with irreversibly reperfused injury, and 10 with occlusive infarction. Before administration of contrast material, there was no significant difference in signal intensity between normal and injured regions on T1-weighted images. After administration of gadodiamide injection (0.2 mmol/kg), the reversibly injured myocardium was indistinguishable from normal myocardium, while the reperfused irreversibly injured zone showed prominent and homogeneous enhancement. Occlusive infarcts showed three zones of differential enhancement consisting of normal, periinfarction, and infarction regions. Gadodiamide injection provides differential enhancement in reversibly reperfused, irreversibly reperfused, and occlusive infarcts. Thus, it may be useful as a marker of reperfusion and extent of infarction after thrombolytic therapy.

Animals↗
PubMed1992

The role of protein kinase-C in gonadotropin-induced ovulation in the in vitro perfused rabbit ovary.

Tumor-promoting phorbol esters are believed to affect ovarian granulosa cell progesterone and prostaglandin (PG) production and possibly ovulation by activating protein kinase-C (PKC). The effects of phorbol esters and PKC inhibitors on ovulation, progesterone, and PG production were examined in an in vitro perfused rabbit ovary. The effect of tranexamic acid, an inhibitor of the conversion of plasminogen activator to plasmin, on phorbol ester-induced ovulation was also examined. Phorbol 12,13-dibutyrate (PdBU), a PKC stimulator, induced ovulation in a dose-related manner in the absence of gonadotropins (56%, 200 nM PdBU; 0%, 0 nM PdBU; P < 0.05). Perfusate progesterone levels were increased only after 600 nM PdBU treatment, and perfusate PGF2 alpha, PGE2, and 6-keto-PGF1 alpha were increased in a dose-dependent fashion (P < 0.05). Staurosporine, a potent inhibitor of the catalytic domain of PKC, and calphostin-C, a specific inhibitor of the diacylglycerol-binding region, inhibited hCG-induced ovulation in a dose-related manner. Gonadotropin-induced ovulation decreased from 73% without staurosporine to 19% with 1.0 microM staurosporine (P < 0.01). Calphostin-C reduced ovulatory efficiency from 60% to 24% (P < 0.01). However, neither inhibitor decreased progesterone or PGF2 alpha production by ovaries exposed to hCG. hCG-induced oocyte maturation was also unaffected by exposure to either staurosporine or calphostin-C. Tranexamic acid reduced phorbol ester-induced ovulatory efficiency from 67% to 37% (P < 0.05). These findings demonstrate that the calcium-dependent PKC pathway is instrumental in gonadotropin-mediated follicular rupture in the rabbit. Although PGs may play an important role in ovulation, they do not appear to be directly responsible for PKC-mediated follicular rupture.

Animals↗
PubMed1992

Helicobacter pylori infection and gastroduodenal disease: a comparison of endoscopic findings, histology, and urease test data.

To determine the prevalence and significance of Helicobacter pylori (H. pylori) infection, biopsies of the antral mucosa were obtained from 139 patients and 43 asymptomatic volunteers. The specimens were examined by hematoxylin-eosin staining and the ureas test. The detection rate of H. pylori by histologic examination was 91.3% in patients with duodenal ulcer, 75.0% in those with combined duodenal and gastric ulcer, 63.6% in those with gastric ulcer, 22.9% in those with gastric carcinoma, 36.4% in those with gastric adenoma, 14.3% in those with gastric hyperplastic polyp, and 51.7% in those with gastritis, and the respective percentages detected by the urease test were 91.3%, 75.0%, 54.5%, 28.6%, 27.3%, 14.3%, and 44.8%. H. pylori was also detected in 10/43 (23.3%) asymptomatic healthy volunteers by histology and the urease test. The prevalence of H. pylori was significantly higher in the patients than in the asymptomatic healthy volunteers (p < 0.05). H. pylori was detected in 62.9% of patients with endoscopic erosive gastritis and in 97.9% of those with histologically proven chronic active gastritis. The urease test was positive in 77/82 patients who were histologically positive for the organism (sensitivity: 93.9%), and it was negative in 98/100 patients who were negative by histology (specificity: 98.0%). Thus, there was over 90% agreement between the urease test and histology. Our investigations showed that H. pylori was closely related to peptic ulcers and antral gastritis, and that the urease test provides a simple, rapid and accurate diagnosis of H. pylori infection.

Adult↗
PubMed1992

Gallium-67-citrate scanning in patients with sarcoid uveitis.

Gallium-67-citrate is useful for characterizing activity in patients with sarcoidosis. Gallium-67 uptake in bilateral symmetrical hilar lymphadenopathy and/or symmetrical salivary glands is typical of this clinical entity. Sarcoidosis is a systemic disease, and uveitis is considered the hallmark of ophthalmic sarcoidosis. We present two cases of ophthalmic sarcoidosis that shows uveal accumulation of 67Ga-citrate associated with clinical symptoms.

Citrates↗
PubMed1992

[The mechanism maintaining severe metabolic alkalosis].

The pathogenesis of severe metabolic alkalosis was studied from the following three points of view; 1) effect of administration of alkalosing agents in rats, 2) amino acids in blood and muscle and 3) renal ammoniagenesis in control and K-depleted rats. The weight gain was significantly depressed in all kinds of alkalosis. Lysine increased remarkably, especially over 10 times in muscle, but Fischer's ratio decreased significantly in blood and muscle of K-depleted rats. Glutamine is the main source in ammoniagenesis, and ammonia (NH4+) is the main substance of H+ secretion from kidney. Though the concentration of glutamine was unchanged in blood and muscle, ammoniagenesis increased 2.5 times, compared with control in renal tubules suspension of K-depleted rat. In conclusion, increase in renal ammonia production would be one of the most important ways to maintain severe metabolic alkalosis.

Alkalosis↗
PubMed1991

Determination of atropine in biological specimens by high-performance liquid chromatography.

A sensitive and selective method for the determination of atropine in biological specimens has been developed. Samples alkalinized with sodium hydroxide were extracted with dichloromethane, and the organic phase was evaporated in a water-bath at 50 degrees C for ca. 10 min. The residue was dissolved in the mobile phase and injected into a reversed-phase column (TSK gel ODS-120A). The retention time for atropine could be varied by changing either the acetonitrile-water ratio in the mobile phase or the pH of the mobile phase. Acetonitrile-water (2:8, v/v) containing 6 mM phosphoric acid was used as mobile phase. Samples of 200 microliters or less were injected into the chromatography and measured at 215 nm. The recoveries of atropine added to drug-free specimens were satisfactory with coefficients of variation of 4% or less. Ninety-two compounds tested did not interfere with the assay of atropine. The method has been applied for monitoring atropine concentrations in cases of organophosphate and drug poisoning.

Adult↗
PubMed1991

Androstenedione and progesterone concentrations in preovulatory follicular fluid correlate with successful fertilization and cleavage of human oocytes in vitro.

OBJECTIVE: To determine if androstenedione (A) and progesterone (P) concentrations in preovulatory follicular fluid (FF) correlate with successful fertilization and cleavage of human oocytes in vitro. DESIGN: A retrospective randomized trial. SETTING: Hospital department of obstetrics and gynecology. PATIENTS: Fifty-five patients, ages 24 to 39 years, with normal menstrual cycles undergoing in vitro fertilization (IVF) for tubal infertility. INTERVENTIONS: Multiple follicular development was induced with clomiphene citrate and human menopausal gonadotropin. MAIN OUTCOME MEASURES: Relationships among FF steroid hormone, morphological maturity of oocyte-corona-cumulus complexes, and fertilization and cleavage of oocytes. RESULTS: Follicles with mature oocyte-corona-cumulus complexes and unfertilized oocytes contained significantly greater amounts of A (P less than 0.05) than those with mature oocyte-corona-cumulus complexes and fertilized ova, indicating the occurrence of atretic changes. Follicles yielding successfully fertilized and cleaved ova had significantly greater amounts of P (P less than 0.05) and A (P less than 0.01) but similar levels of 17 beta-estradiol compared with follicles yielding fertilized ova that failed to cleave. CONCLUSIONS: Follicles yielding oocytes that cleaved as a result of IVF have both a shift in steroidogenesis from estrogen to progestin accumulation and declining aromatase activity, thus reflecting progressive luteinization of the follicles.

Adult↗
PubMed1991

Effects of prolactin on fertilization and cleavage of human oocytes.

The effects of PRL on fertilization and cleavage of human oocytes and subsequent pregnancy were studied. Forty-five patients (47 cycles) with euprolactinemic normal menstrual cycles undergoing in vitro fertilization (IVF) for the treatment of tubal infertility were selected for this study. The patients were divided into three groups dependent upon their mean serum PRL concentrations for the 3 days prior to oocyte retrieval; hypoprolactinemic (less than 10 micrograms/l), euprolactinemic (10-30 micrograms/l) and hyperprolactinemic cycles (greater than or equal to 30 micrograms/l). Multiple follicular development was induced with hMG, and 10 patients were randomized to receive bromocriptine beginning with the previous menstrual cycle. In the hypoprolactinemic cycle group, the fertilization rate was significantly lower than in the hyperprolactinemic cycle group, and the cleavage rate was significantly lower than in the other groups. The fertilization rates and the cleavage rates in the hyperprolactinemic cycle group were higher than those in the euprolactinemic cycle group; however, these differences were not statistically significant. While the pregnancy rates in the euprolactinemic cycle group were higher than in the other two groups, the numbers were too small for meaningful statistical comparison. The present study demonstrates that below normal concentrations of PRL have deleterious effects on IVF outcome. These data suggest that PRL may play a beneficial stimulatory role in oocyte maturation and the acquisition of developmental capacity.

Adult↗
PubMed1990

An evaluation of an in vivo local sound speed estimation technique by the crossed beam method.

An in vivo local sound speed estimation technique, using the crossed beam method, has been proposed and its applicability was evaluated. At first, the potential of this technique was studied by a mapping simulation using the ray tracing technique followed by an experiment with a cylindrical agar phantom. The simulation result showed that an exact measurement of local sound speed values was difficult, but the sound speed information for the local region (its relative magnitude to the surrounding medium) was emphasized as a refraction mapping pattern. The experimental results agreed well with the calculation results. Furthermore, a clinical application was performed, using the clinical system (modified electronic linear scanner), on two liver tumor patients.

Acoustics↗
PubMed1990

Incidence and properties of renal masses and asymptomatic renal cell carcinoma detected by abdominal ultrasonography.

Renal ultrasonography was performed in 45,905 adults, including 41,364 without any signs suggesting urinary tract malignancies, 1,667 with microscopic hematuria only and 2,874 with some signs of malignancy. Renal lesions were found in 355 adults (0.858%) in the asymptomatic, 39 (2.3%) in the microscopic hematuria and 75 (2.6%) in the symptomatic groups, respectively. Renal cell carcinoma was found in 35 (7.5%) lesions: 19 (5.4%) in the asymptomatic, none in the microscopic hematuria and 16 (21.3%) in the symptomatic groups. A total of 47 patients, including 12 other renal cell carcinoma patients transferred from related hospitals, was grouped into 28 without and 19 with symptoms. Primary tumor size and clinical stages were significantly smaller and lower, respectively, in the asymptomatic group than in the symptomatic group. Radical nephrectomy was performed in all but 2 asymptomatic patients. The 5-year survival rates after nephrectomy were 94.7 and 60.9% for the asymptomatic and symptomatic groups, respectively (p less than 0.01). The results indicate that ultrasonography is a useful tool to detect low stage asymptomatic renal cell carcinoma at low cost.

Carcinoma, Renal Cell↗
PubMed1990

Reversible and irreversible injury in the reperfused myocardium: differentiation with contrast material-enhanced MR imaging.

Thrombolytic agents are being used with increasing frequency to produce reperfusion of acute myocardial infarction in humans. This study was designed to assess the potential of a magnetic resonance (MR) contrast agent, the manganese chelate of N,N'-bis(pyridoxal-5-phosphate) ethylenediamine-N,N'-diacetic acid (DPDP), in differentiating between reversible and irreversible myocardial injury during reperfusion. Ischemia was produced in rats by occlusion of the left coronary artery for either 15 minutes (n = 10) or 2 hours (n = 10), followed in both cases by 30 minutes of reperfusion. Signal intensity (SI) was measured before and after (every 15 minutes for 1 hour) the administration of Mn-DPDP. Prior to intravenous injection of the contrast agent, no significant difference in SI was observed between normal and reversibly or irreversibly injured myocardium. Mn-DPDP produced greater enhancement of SI of the irreversibly injured region compared with normal myocardium. There was no differential enhancement of the reversibly injured region compared with normal myocardium. Thus, Mn-DPDP is useful in discriminating reversible from irreversible injury in reperfused myocardium.

Animals↗
PubMed1990

The effect of the follicular fluid adenosine 3',5'-monophosphate degradation rate on successful fertilization and cleavage of human oocytes.

Follicular fluid (FF) and oocytes were obtained from 19 women for in vitro fertilization. Ovulation was induced with clomiphene citrate and human menopausal gonadotropin. Thirty-seven FF samples containing mature oocyte-corona-cumulus complexes were used to measure steroids, gonadotropins, and cAMP. The FF specimens were divided into three groups: follicles yielding ova that were fertilized and cleaved (group A), follicles containing fertilized ova without further cleavage (group B), and follicles containing nonfertilized oocytes (group C). The FF levels of progesterone, 17 beta-estradiol, LH/hCG, and FSH did not differ significantly among the groups. Mean FF cAMP concentrations declined from 17.5 +/- 2.5 pmol/mL 15 min after follicle aspiration to 3.6 +/- 0.9 pmol/mL after 3 h. The initial FF cAMP concentration did not differ significantly among three groups. However, the cAMP degradation rate in group A (119 +/- 13 X 10(-4) pmol/min) was significantly greater than that in group B (62 +/- 10 X 10(-4) pmol/min) or group C (75 +/- 8 X 10(-4) pmol/min). In conclusion, an increased intrafollicular cAMP degradation rate was associated with successful fertilization and cleavage of human oocytes in vitro. These data suggest that the degradation rate of FF cAMP may be a marker of optimal follicular development and oocyte maturation.

Adult↗
PubMed1990

Effects of antioxidants on V79 Chinese hamster cells treated with ferric nitrilotriacetate.

The cytotoxic effects of ferric nitrilotriacetate (Fe-NTA) have been considered to be caused by free radicals produced by the drug. The present study was carried out to determine whether or not cytotoxic effects of Fe-NTA on cell growth and lipoperoxide formation of Chinese hamster cells were reduced by antioxidants. Using a spin trapping technique, we found that hydroxyl radical formation in the cells increased in the presence of Fe-NTA. Antioxidants, with the exception of superoxide dismutase, slightly inhibited production of the hydroxyl radical. Mannitol significantly reduced lipoperoxide formation, but other antioxidants did not. However, the growth inhibitory effects of Fe-NTA were not attenuated by these antioxidants. These results indicated that the cytotoxic effects of Fe-NTA may be mostly due to unknown factors other than oxygen free radicals.

Animals↗
PubMed1990

Changes in the levels of lipoperoxide and antioxidant factors in human placenta during gestation.

The concentration of lipoperoxides in maternal blood increases as gestation progresses. The concentration in pregnant women at 40 weeks gestation is 1.6 times higher than in nonpregnant women. The concentration in the cord blood, however, is 70% lower than that in maternal blood. To study the role of placental tissue in the difference in the lipoperoxide concentration between the cord blood and maternal blood, we investigated the lipoperoxide concentration, antioxidant activities and in vitro lipoperoxide formation in placental tissue during pregnancy. The lipoperoxide concentration was 50% lower in placental tissue of 40 weeks gestation than in tissue of 5-11 weeks gestation. Catalase and superoxide dismutase activities in placental tissues increased as gestation progressed, while glutathione peroxidase activity and alpha-tocopherol concentration did not change significantly during the gestational period. The in vitro formation of lipoperoxides in placental tissue decreased as gestation progressed. These results show that placental tissue suppresses lipoperoxide formation in the late gestational age, lowers the concentration of lipoperoxides in the blood and protects the fetus against oxygen toxicity.

Antioxidants↗