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Biomedical subjects

K Nakada

Publications and source records attributed to K Nakada.

At least 19 recordsLinked to original sources
PubMed1992

Antibody to the inositol trisphosphate receptor blocks thimerosal-enhanced Ca(2+)-induced Ca2+ release and Ca2+ oscillations in hamster eggs.

The sulfhydryl reagent thimerosal enhanced the sensitivity of hamster eggs to injected inositol 1,4,5-trisphosphate (InsP3) or Ca2+ to generate regenerative Ca2+ release from intracellular pools. A monoclonal antibody (mAb) to the InsP3 receptor blocked both the InsP3-induced Ca2+ release (IICR) and Ca(2+)-induced Ca2+ release (CICR). The mAb also blocked Ca2+ oscillations induced by thimerosal. The results indicate that thimerosal enhances IICR sensitized by cytosolic Ca2+, but not CICR from InsP3-insensitive pools, and causes repetitive Ca2+ releases from InsP3-sensitive pools.

Animals↗
PubMed1992

Block of Ca2+ wave and Ca2+ oscillation by antibody to the inositol 1,4,5-trisphosphate receptor in fertilized hamster eggs.

The concentration of cytoplasmic free calcium (Ca2+) increases in various stimulated cells in a wave (Ca2+ wave) and in periodic transients (Ca2+ oscillations). These phenomena are explained by inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release (IICR) and Ca(2+)-induced Ca2+ release (CICR) from separate intracellular stores, but decisive evidence is lacking. A monoclonal antibody to the IP3 receptor inhibited both IICR and CICR upon injection of IP3 and Ca2+ into hamster eggs, respectively. The antibody completely blocked sperm-induced Ca2+ waves and Ca2+ oscillations. The results indicate that Ca2+ release in fertilized hamster eggs is mediated solely by the IP3 receptor, and Ca(2+)-sensitized IICR, but not CICR, generates Ca2+ waves and Ca2+ oscillations.

Animals↗
PubMed1992

Helicobacter pylori infection induces a decrease in immunoreactive-somatostatin concentrations of human stomach.

Immunoreactive-somatostatin (ir-somatostatin) concentrations of the gastric mucosa and gastric juice with Helicobacter pylori infection were measured in the human stomach. One hundred seventy-one patients (106 males, 65 females; mean age, 52.0; range, 19-84 years) were registered. Gastric juice and mucosa were obtained with the usual endoscopy procedure. Somatostatin concentration was measured by radioimmunoassay. The ir-somatostatin concentrations in the H. pylori-negative group were significantly higher than in the positive group gastric mucosa, whereas its levels in gastric juice tended to decrease with H. pylori infection. There was an inverse correlation between luminal ammonia levels and ir-somatostatin concentrations of the gastric mucosa. On the other hand, ir-somatostatin concentrations of the gastric mucosa significantly decreased with chronic and active inflammatory change. This decrease was not correlated with the grade of active inflammation, which was in close relation to H. pylori infection, but with the grade of chronic inflammation. These results indicate that H. pylori may reduce ir-somatostatin concentrations of the human stomach and that its effect is partly mediated via luminal ammonia produced by H. pylori.

Adult↗
PubMed1992

Effect of luminal administration of thyrotropin-releasing hormone or somatostatin on gastric pH and interaction of these peptides in rats.

The effect of intraluminal administration of thyrotropin-releasing hormone (TRH) on gastric pH and release of luminal somatostatin, and a possible interrelationship between TRH and somatostatin in the rat stomach were studied. TRH was administered into the stomach via an intragastric tube at various doses (50 pg/kg-10 micrograms/kg) and gastric pH was measured after 15 min. The intraluminal administration of TRH significantly decreased gastric pH at doses over 1.0 ng/kg. Time-course studies at a dose of 100 ng/kg TRH exhibited a significant decrease in gastric pH at 15, 30 and 60 min. Furthermore, TRH administration caused a significant increase in immunoreactive-somatostatin (ir-somatostatin) concentrations in the gastric wall and a significant decrease in ir-somatostatin concentrations in the gastric juice. On the other hand, intraluminal administration of somatostatin caused a significant increase in ir-TRH concentrations in the gastric wall and a significant decrease in ir-TRH concentrations in the gastric juice, and significantly raised gastric pH at 5 min. These findings suggest that luminal TRH may exert a regulatory effect on gastric acid secretion, and that TRH may have a possible interaction with somatostatin in the modulation of gastric acid secretion.

Animals↗
PubMed1992

Single photon emission computed tomography using 201Tl chloride in pulmonary nodules: comparison with 67Ga citrate and 99mTc-labeled hexamethylpropyleneamine-oxime.

A single photon emission computed tomography (SPECT) with 201Tl chloride (Tl-201) was carried out prospectively in 50 patients with pulmonary nodules and its diagnostic value was compared with those of 67Ga citrate (Ga-67) and 99mTc-labeled hexamethylpropyleneamine-oxime (Tc-99m-HMPAO). Tl-201 SPECT provided 88% (early)-91% (delayed) sensitivity, 85% (early and delayed) specificity and 87% (early)-89% (delayed) accuracy. The sensitivity of the Tl-201 planar image was 56 (early)-62% (delayed), which was significantly lower than that of SPECT. Delayed SPECT images at 2 hour postinjection were more preferable to disclose the malignant pulmonary nodule than early SPECT images at 15 minutes postinjection. The application of SPECT with Ga-67 failed to improve the sensitivity of planar imaging for malignant pulmonary nodules. Tc-99m-HMPAO was concentrated in 62% of 13 patients with malignant pulmonary nodules, which was slightly higher than Ga-67 in 54% of 28 patients. In an analysis of the histologic types of lung cancer, the sensitivity of Tl-201 was not significantly different in all types. On the other hand, Ga-67 was positive only in 25% of 12 patients with adenocarcinoma. A combination of SPECT and Tl-201 is the best choice among routine scintigraphic techniques for depicting malignant pulmonary nodules. The Tl-201 SPECT image may play a complementary role in the characterization of pulmonary nodules which are revealed on a plain radiograph and computed tomography.

Adult↗
PubMed1992

Evidence that metalloendoproteases are involved in gamete fusion of Ciona intestinalis, ascidia.

The use of specific inhibitors and substrates of metalloendoproteases provides evidence that in many systems these enzymes are involved in membrane fusion events. In this study, we investigated whether metalloendoproteases are involved in Ciona sperm-egg fusion. In vitro fertilization assays with the metal chelator 1,10-phenanthroline, specific metalloendoprotease substrates, and the vital stain Hoechst 33342 suggested that a Zn(2+)-dependent metalloendoprotease(s) takes part in Ciona sperm-egg fusion. Furthermore, electrophysiological recordings showed that insemination carried out in the presence of either 1,10-phenanthroline or the substrate CBZ-Gly-Phe-NH2 fails to induce fertilization potential or any other change in membrane potential. These results support the hypothesis that in Ciona intestinalis, a metalloendoprotease(s) is functional in gamete fusion.

Animals↗
PubMed1992

Effect of serotonin on the immunoreactive thyrotropin-releasing hormone concentrations of the rat stomach.

The effects of serotonin and its related compounds on immunoreactive thyrotropin-releasing hormone (ir-TRH) concentrations of the rat stomach wall and gastric juice were studied. Either serotonin, cyproheptadine or GR38032F was injected intraperitoneally, and the rats were decapitated at various times after the injection. ir-TRH concentrations of the stomach wall and gastric juice were measured by radioimmunoassay, and gastric serotonin concentrations were measured by HPLC. ir-TRH concentrations of the stomach wall decreased, and ir-TRH concentrations of gastric juice increased significantly after serotonin injection. On the other hand, both cyproheptadine and GR38032F did not affect ir-TRH concentrations of the stomach. The effects of serotonin on ir-TRH concentrations of the stomach were significantly blocked by the pretreatment of cyproheptadine and GR38032F. The reciprocal changes of gastric ir-TRH and serotonin concentrations were observed without changes in gastric juice pH. These findings suggest that serotonin stimulates ir-TRH release from the stomach wall into gastric juice, and the effects of serotonin on ir-TRH release may be partly mediated via 5-HT2- and 5-HT3-receptors.

Animals↗
PubMed1992

Radioimmunoassay for the determination of 2-methoxyestriol concentration in plasma of pregnant women.

A specific assay method has been developed for the determination of 2-methoxyestriol in plasma of pregnant women. The quantitation was achieved by radioimmunoassay after extraction of the plasma with ethyl acetate and purification on a Sephadex LH-20 column. In order to obtain the immunogen for 2-methoxyestriol, 6-oxo-2-methoxyestriol was converted to its 6-(O-carboxymethyl)oxime derivative. The derivative was then coupled to bovine serum albumin by the mixed anhydride method, and rabbits were immunized with this conjugate. The antiserum obtained was partially purified by affinity chromatography on estrone 17-(O-carboxymethyl)oxime-aminohexyl Sepharose conjugate to eliminate the cross-reactive antibodies. Plasma 2-methoxyestriol concentrations in pregnancy were estimated to be mean values of 41.1 pg/ml (12th-14th week), 85.3 pg/ml (27th-29th week), and 97.5 pg/ml (37th-41st week).

Cross Reactions↗
PubMed1992

[Effects of a non-ionic low osmolar contrast medium on thyroidal radioiodine uptake in rats].

Recently non ionic low osmolar contrast media (NILOCM) have been widely used in radiographic contrast studies. These new agents have a great advantage over conventional ionic high osmolar contrast media (IHOCM) in low chemical toxicity and good X-ray absorption. However, their effects on thyroid function, especially on thyroidal radioiodine uptake (TRIU), are still unknown and it is not clear how long NILOCM interfere with TRIU. Therefore, the extent of the interference with TRIU caused by previous NILOCM injection was examined using rat thyroid. Male WKA rats were divided into four groups and fed under different dietary conditions, A) routine diet for rats; B) low iodine diet (LID) for 1 week, C) LID for 2 weeks, and D) LID for 8 weeks. Iopamidol was used as NILOCM, and iothalmate, one of IHOCM, was also employed for comparative study. After feeding, some rats in each group were injected with 300 mgI/kg. b.w. of iopamidol or iothalmate. The remaining rats in each group received saline injection as the control. At day 1, 2, 3, 7, and 14 following injection, I-131 was administered intravenously and a 24 hour TRIU (% dose/mg tissue) was measured in each group. Thyroidal iodine content (TIC: micrograms I/mg tissue) at day 1, 7, and 14 was also measured in group A, C, and D. Until day 3, severe suppression on TRIU was observed in all groups, and TIC elevated at day 1 in iothalmate-injected rats. In iopamidol-injected rats, TRIU and TIC recovered after then, and reached the same levels as those in control rats until day 14 except for group D. However, TRIU was still significantly lower and TIC levels in group D was higher at day 14 in iothalmate-injected rats. It is concluded that iopamidol has less effects on TRIU and TIC with a shorter period of recovery than iothalmate. This results maybe beneficial to the patients who were injected NILOCM prior to radioiodine scintigraphy.

Animals↗
PubMed1991

Effects of water-immersion-induced stress and intraperitoneal administration of brain-gut peptides upon immunoreactive thyrotropin-releasing hormone and prostaglandin E2 concentrations in the rat stomach.

The effects of water-immersion-induced stress and intraperitoneal (i.p.) administration of selected neuropeptides on the levels of thyrotropin-releasing hormone (TRH) and prostaglandin E2 (PGE2) were studied in the rat stomach. Water-immersion caused a significant decrease immunoreactive-TRH (ir-TRH) concentrations in the stomach, and a significant increase in ir-TRH concentrations in the gastric juice. The concentrations of PGE2 were significantly increased at 0.5-4 hrs, and significantly decreased at 6-8 hrs after water-immersion. In the experiment of i.p. administration of selected neuropeptides, the level of ir-TRH in the stomach was significantly decreased after VIP injection, whereas it was significantly increased after beta-endorphin injection. The concentration of PGE2 was significantly decreased in the stomach after i.p. administration of TRH and VIP. However, it did not change after beta-endorphin injection. These results indicate that some neuropeptides may participate in regulating the endogenous level of PGE2 and that these interrelations between neuropeptides and PGE2 may be important as ulcerogenic factors in stress ulcers induced by water-immersion in the rat.

Animals↗
PubMed1991

Single photon emission computed tomography with Tc-99m-dimercaptosuccinic acid in patients with upper urinary tract infection and/or vesicoureteral reflux.

By means of Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy, an established method for assessing renal cortical damage, we evaluated the pick-up rate for renal defects (scars) by single photon computed tomography (SPECT) and planar images of 10 normal volunteers, and 58 patients (70 scintigrams) with upper urinary tract infections, most of whom had a history of vesicoureteral reflux (VUR). The positive study rate for renal defects depended on the severity of VUR. The overall positive rates for renal cortical defects obtained by DMSA SPECT imaging and DMSA planar imaging were 60% and 43%, respectively, and the difference between these was significant (p less than 0.005). The mean absolute individual renal uptake (/injected dose) at 2 hours post-injection was decreased in kidneys with defects detected by SPECT alone. The positive study rate for intravenous urography (IVU) depended on the grade of VUR and was 15% overall. DMSA SPECT imaging detects renal cortical defects at greater frequency than previously achieved.

Adolescent↗
PubMed1991

[Gallbladder function and CCK after gastrectomy].

Postgastrectomy cholelithiasis has become a problem and biliary tract dyskinesia has been cited as an etiologic factor. CCK is the most important gut hormone with respect to biliary tract function, so we conducted an experimental study of postgastrectomy gallbladder function and CCK levels which gave the following results: 1. Although postprandial gallbladder contraction for the most part occurred in response to endogenous CCK, another mechanism (the gastro-cholecystic reflex) seemed to be responsible for some of them. 2. The postgastrectomy decrease in postprandial gallbladder contraction appeared to be due to disappearance of this gastro-cholecystic reflex. 3. Gallbladder contraction occurred in association with postprandial CCK secretion following total gastrectomy and Roux-en-Y reconstruction, but the altered food passage route caused changes in the dynamics of CCK secretion, and this is believed to have had an influence on the gallbladder contractile response.

Animals↗
PubMed1990

[Cystic papillary carcinoma of the thyroid--sonographic-pathologic correlation].

Ultrasonographic findings of 13 patients with cystic papillary carcinoma (CPC) of the thyroid gland were reviewed retrospectively correlating with pathologic findings. A 4-6 cm oval cystic structure with a 2-3 cm pedunculated projection of mass into the lumen was the characteristic sonographic findings of CPC. However, other sonographic findings of CPC simulated adenoma, nodular goiter or follicular carcinoma. Pathological investigation revealed that malignant cells tended more to be located in intracystic pedunculated mass and/or pericystic region than in the cyst wall. In most of the cases cyst walls were chiefly composed of granulomatous tissue with scattered malignant cells. These findings indicate that the needle biopsy should be done under ultrasonographic guidance to obtain sufficient material for accurate cytologic and/or pathologic diagnosis, thereby reducing the number of false negative cases.

Adult↗
PubMed1990

The clinical features and prognosis of rhabdomyosarcoma: follow-up studies on pediatric tumors from the Japanese Pediatric Tumor Registry 1971-1980. Part II. Committee of Malignant Tumors, Japanese Society of Pediatric Surgeons.

A retrospective study was conducted on 126 patients with rhabdomyosarcoma enrolled in the Japanese Pediatric Tumor Registry between 1971 and 1980. The age of the patients ranged from less than 1 year to 15 years, and the male to female ratio was 1.3:1.0. Primary sites included the pelvis (37.3 per cent), abdomen (23.8 per cent), head and neck (21.4 per cent), thorax (9.5 per cent), extremities (6.4 per cent) and unknown (1.6 per cent). According to the staging system of the Japanese Society of Pediatric Surgeons, the extent of disease was classified into stages Ia (26.2 per cent of the total); Ib (14.6 per cent); II (12.6 per cent), III (29.1 per cent) and IV (17.5 per cent). The clinical stage was significantly correlated with survival outcome in this series (p less than 0.05). Age, sex, histology and primary site per se had no independent prognostic influence on tumor-free survival. With regard to treatment modalities, surgery was performed in 94.0 per cent of the patients, and radiotherapy at a mean dose of 37 Gy, and/or multi-agent chemotherapy in 41.7 per cent and 80.0 per cent, respectively. The patients who underwent total excision had a better survival outcome than those who did not (p less than 0.05). Combination chemotherapy such as VAC was more commonly administered in the latter study period. The overall 2-year tumor-free survival rate (2YTFSR) significantly improved from 24.0 per cent in the former period between 1971 and 1975 to 48.7 per cent in the latter period between 1976 and 1980 (p less than 0.05).

Adolescent↗
PubMed1990

The effects of histamine on the concentrations of immunoreactive thyrotropin-releasing hormone in the stomach and hypothalamus in rats.

The effects of histamine and its related compounds on the concentrations of immunoreactive thyrotropin-releasing hormone (ir-TRH) in the stomach, gastric juice and hypothalamus in rats were studied. Histamine, ranitidine or ethanolamine was injected intraperitoneally, and the rats were decapitated at various times after the injection. Ir-TRH concentrations in the stomach, gastric juice and hypothalamus were measured by a radioimmunoassay. Ir-TRH concentrations in the stomach decreased significantly after histamine injection and increased significantly after ranitidine injection in a dose-dependent manner, but did not change with ethanolamine. Ir-TRH concentrations in the gastric juice increased in a dose-dependent manner, peaking at 30 min after histamine injection, and its effect was blocked with ranitidine. Ir-TRH concentrations in the hypothalamus elevated significantly after histamine injection and reduced significantly after ranitidine injection, but did not change with ethanolamine. The effects of histamine on ir-TRH concentrations in the stomach and hypothalamus were significantly blocked with ranitidine, but not with ethanolamine. These findings suggest that histamine stimulates ir-TRH release from the stomach and inhibits ir-TRH release from the hypothalamus, and that these effects of histamine on ir-TRH release are mediated via an H2-receptor.

Animals↗
PubMed1990

Application of monoclonal antibodies to the detection of black-pigmented Bacteroides spp. in subgingival plaques by immunoslot blot assay.

The aim of the present study was to assess the application of monoclonal antibodies to the detection of black-pigmented Bacteroides spp. in subgingival plaques by immunoslot blot assay. Subgingival plaque samples from adult periodontal patients were examined by immunoslot blot assay with monoclonal antibodies that specifically recognize Bacteroides gingivalis, Bacteroides intermedius serogroups I and II, and Bacteroides melaninogenicus. The assay can detect specifically these Bacteroides spp. in the subgingival plaques. Therefore, we investigated the distribution of these Bacteroides spp. in the subgingival plaques of patients classified by Russell's periodontal index. Reactivities of their plaques with monoclonal antibodies toward B. gingivalis and B. intermedius serogroup I were clearly related to the severity of the periodontal disease, but this was not the case with B. intermedius serogroup II and B. melaninogenicus. These results indicate that this immunoslot blot assay using monoclonal antibodies toward these Bacteroides spp. provides simple detection and monitoring of these organisms in periodontal patients.

Adult↗