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Biomedical subjects

K Nakada

Publications and source records attributed to K Nakada.

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

[Detection and localization of parathyroid adenomas and hyperplasias in patients with hyperparathyroidism using thallium-201/technetium-99m parathyroid subtraction scintigraphy].

201Tl/99mTc subtraction scintigraphy (TTS) has been recognized as a useful procedure in the preoperative localization of hyperfunctioning parathyroid glands. Ninety-one patients suspected of hyperparathyroidism (HPT) were studied with TTS for the localization of lesions and 59 patients out of those had a neck exploration and parathyroidectomy which allowed for clinical correlation of pathologic findings with the imaging results. The weight of 30 glands of adenoma ranged 0.100 to 11.700 g (1.840 +/- 0.446 g (mean +/- SE)). The weight of 88 glands of hyperplasia ranged 0.025 to 7.000 g (0.623 +/- 0.100 g). Overall sensitivity and specificity were 47% and 54%, respectively. The sensitivity for the adenoma and the hyperplasia was 87% and 33%, respectively. The specificity for them was 57% and 52%. There was significant difference for the detection between adenomas and hyperplasias. TTS is more useful for the localizing diagnosis of parathyroid adenomas than parathyroid hyperplasia in a patient with hyperfunctioning parathyroid state.

Adenoma↗
PubMed1993

Development of inositol trisphosphate-induced calcium release mechanism during maturation of hamster oocytes.

Mature hamster eggs exhibit repetitive increases in the intracellular Ca2+ concentration ([Ca2+]i) at fertilization, caused by inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ release (IICR) from stores. Oscillating Ca2+ rises also occurred in inseminated immature oocytes at the germinal vesicle (GV) stage but the peak [Ca2+]i of each response was about half of that in mature eggs. Like the responses to sperm in the mature egg, those in the immature oocyte were also blocked by injection of a monoclonal antibody against the InsP3 receptor (18A10). Compared with mature eggs, immature oocytes were more sensitive to externally applied serotonin which caused repetitive IICR, but each response was smaller. The development of the IICR mechanism during oocyte maturation was investigated using iontophoretic injection of InsP3 and Ca2+ imaging with fura 2. In immature oocytes the rise in [Ca2+]i with an InsP3 pulse of 1.2 nA for 1 sec was 35% of that in mature eggs. The response increased with increasing doses of InsP3. The nearly maximum response, obtained with a 20-nA 2-sec pulse, was 80% of that in mature eggs, suggesting that immature oocytes are less sensitive to InsP3 but that most of Ca(2+)-releasable stores are already present in the immature oocyte. IICR developed in two phases during in vivo maturation. The sensitivity to InsP3 increased gradually between the GV stage and prometaphase of the first meiosis. Then a nonlinear dose-response relation developed during the second meiosis to metaphase II, resulting in regenerative, propagating Ca2+ release induced by a threshold pulse of 1 nA for 1 sec in mature eggs. Similar changes occurred during in vitro maturation of oocytes isolated from follicles at GV stage and cultured for up to 16 hr. The development of IICR is thought to be a prerequisite factor for the acquisition of the ability of an egg to undergo normal fertilization.

Animals↗
PubMed1993

Essential role of the inositol 1,4,5-trisphosphate receptor/Ca2+ release channel in Ca2+ waves and Ca2+ oscillations at fertilization of mammalian eggs.

At fertilization mammalian eggs exhibit repetitive rises in the cytoplasmic Ca2+ concentration (Ca2+ oscillations), associated with propagating Ca2+ waves in the initial responses. The Ca2+ oscillation causes cortical granule exocytosis and resumption of second meiosis and affects later embryonic development. Recent studies using a function-blocking monoclonal antibody to the inositol 1,4,5-trisphosphate (InsP3) receptor/Ca2+ release channel demonstrated direct evidence that InsP3-induced Ca2+ release (IICR) from intracellular stores operates at fertilization of the hamster egg and that IICR is essential in the initiation, propagation, and oscillation of the sperm-induced Ca2+ rises. Ca(2+)-induced Ca2+ release (CICR) has also been suggested, but a sensitizing action of Ca2+ on the InsP3 receptor, i.e., Ca(2+)-sensitized IICR, can serve as a regenerative process of Ca2+ release and could be the basis for Ca2+ waves and Ca2+ oscillations. It is now apparent that signal transduction at fertilization is dependent on sperm-stimulated activation of phospholipase C which causes hydrolysis of phosphatidylinositol bisphosphate and production of InsP3, leading to IICR. On the other hand, Ca2+ signaling at fertilization of the sea urchin egg may also involve ryanodine receptor-mediated CICR.

Animals↗
PubMed1993

Hemangioma of the upper arm associated with massive hemorrhage in a neonate.

A rare case of an ulcerated hemangioma of the upper arm in a neonate is described herein. Resection of the huge hemangioma, which occupied the axilla and extended down the entire length of the upper arm, was necessary due to massive hemorrhage from the ulcer and progressive heart failure caused by the arteriovenous fistula in the hemangioma. After complete resection of the hemangioma, extensive defects of the skin and subcutaneous tissue were replaced by a skin flap closure technique which involved considerable difficulty. However, the arm gradually recovered its size and function with good wound healing. The present case illustrates that rapid surgical intervention may be required to prevent clinical deterioration in such cases.

Arm↗
PubMed1993

An infant with bilateral adrenal neuroblastoma found by mass-screening: report of a case.

A male infant with bilateral adrenal neuroblastoma found by mass-screening is herein reported. The patient presented with almost equal-sized tumors, each remaining confined to the respective adrenal gland without crossing the midline. No other tumorous lesion was evident. The two adrenal tumors had similar histologic features and appeared to have grown concurrently. Such simultaneous occurrence of primary adrenal neuroblastoma is unusual, and appears to reflect the multicentric origin of this tumor.

Adrenal Gland Neoplasms↗
PubMed1993

The role of thyrotropin-releasing hormone (TRH) in the pathogenesis of water-immersion stress in rats--inhibition of TRH release from the stomach by atropine, ranitidine or omeprazole.

The role of thyrotropin-releasing hormone (TRH) in the development of gastric erosions and ulcers induced by water-immersion stress was studied. Intraperitoneally administered bethanechol induced a decrease in the gastric wall immunoreactive TRH (ir-TRH) concentrations and an increase in gastric juice ir-TRH concentrations in a dose-related manner, while atropine induced an increase in gastric wall ir-TRH concentrations and a decrease in gastric juice ir-TRH concentrations under non-stress condition. Intraperitoneally administered omeprazole did not influence gastric wall ir-TRH concentrations but elevated gastric pH. Water-immersion stress induced a decrease in gastric wall ir-TRH concentrations and an increase in gastric juice ir-TRH concentrations with a decrease in gastric pH prior to ulcer formation. Pretreatment with atropine or ranitidine inhibited the development of stress ulcers, reduced changes in ir-TRH concentrations in the gastric wall and gastric juice, and induced an increase in gastric pH. Omeprazole inhibited stress ulcer formation and changes in gastric wall and gastric juice ir-TRH concentrations. These results suggest that TRH release from the stomach wall into gastric juice is of importance in the pathogenesis of stress ulcer and that its release is mediated by both muscarinergic and histaminergic (H2) systems. Furthermore, omeprazole has an inhibitory effect on TRH release under stress ulcer.

Animals↗
PubMed1993

Captopril renoscintigraphy with Tc-99m DTPA in patients with suspected renovascular hypertension. Prospective and retrospective evaluation.

Sensitivity and specificity of captopril renoscintigraphy (CRS) with Tc-99m DTPA has been analyzed in 41 cases, 16 with renovascular hypertension (RVH) and 25 with non-RVH. The sensitivity and specificity of the baseline study were 63% (10/16) and 63% (12/19), respectively, based on the split renal function study in which the lower limit of normal was assumed to be 42% of the total renal uptake. Captopril renoscintigraphy yielded 67% (12/18) sensitivity and 76% (19/25) specificity. The low specificity of CRS was due to the application of a prospective criterion of the captopril-induced reduction rate (CRR) of less than -20%, which was calculated from the renal uptake before and after captopril. When criteria of CRR less than -25% were used, the specificity of CRS was improved to 96%, but the sensitivity declined to 61%. Changes in the configuration of the renogram induced by captopril also had high specificity but low sensitivity. Renovascular hypertension was most likely when criteria for both CRR and the renogram were fulfilled. These criteria often were diagnostic in patients with bilateral renal artery stenosis that showed variable scintigraphic responses to captopril challenge. Captopril renoscintigraphy is a very specific means to evaluate RVH, but may have limitations in certain clinical situations such as poorly preserved function of the affected kidney, prior long-term administration of captopril, prior surgical manipulation of stenotic renal artery, and chronic renal parenchymal damage.

Adult↗
PubMed1993

Expressions of N-myc and ras oncogene products in neuroblastoma and their correlations with prognosis.

Thirty-six neuroblastomas were studied to determine the clinical significance of the N-myc gene product, N-myc, and the ras gene product, p21. The expressions of both gene products were analyzed immunohistochemically using formalin-fixed paraffin sections. Neuroblastoma cells were positive for N-myc expression in 13 cases and for p21 expression in 19 cases. N-myc expressions showed no significant relation to any clinical prognostic factor, whereas p21 expression was well correlated with clinical staging and Shimada's classification. There was a tendency for p21 expression to be low in N-myc(+) tumors, whereas p21 expression was frequently detected when N-myc expression was absent. The survival rate for N-myc(-) patients was significantly higher than for N-myc(+) patients (P < 0.01). The survival rate for p21(+) patients was significantly higher than for p21(-) patients (P < 0.001). In addition, N-myc(+) and p21(-) patients showed a strong tendency towards a poor prognosis, whereas a combination of p21(+) and N-myc(-) indicated a good prognosis (P < 0.01). The results suggest that expressions of N-myc and p21 detected by immunohistochemical staining could be among the most reliable prognostic indicators in neuroblastoma patients.

Adolescent↗
PubMed1993

[Role of 99mTc-labeled RBC SPECT in the diagnosis of hepatic hemangioma--comparison with US, CT and angiography].

The roles of planar imaging and SPECT with 99mTc-labeled RBC, US, Dynamic CT and angiography in the diagnosis of hepatic hemangioma were evaluated. The study group consisted of 18 patients with a total of 40 hemangiomas and 13 patients with a total of 21 non-hemangiomas. Among these patients, 5 patients with a total of 8 hemangiomas and 10 patients with a total of 14 non-hemangiomas were diagnosed by operation and biopsy. In all 40 hemangiomas, sensitivity for planar imaging was 35%, SPECT 50%, US 53%, Dynamic CT 82% and angiography 81%, respectively. When the tumor size was greater than 2.2 cm by SPECT and 2.8 cm by planar imaging, their sensitivity for both methods was 100%. Specificity for planar imaging was 100%, SPECT 95%, US 81%, Dynamic CT 100% and angiography 83%, respectively. One patient with hepatocellular carcinoma diagnosed by angiography showed increased uptake on SPECT. Because of the highest accuracy for SPECT in hemangioma greater than 2.0 cm, SPECT should be considered to be the method of choice for noninvasive diagnosis of hemangioma.

Adult↗
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↗