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Biomedical subjects

T Nakai

Publications and source records attributed to T Nakai.

At least 253 records · Page 14Linked to original sources
PubMed1993

Regulation of 18-oxocortisol and 18-hydroxycortisol by the renin-angiotensin system and ACTH in man.

Based on urinary excretion studies the secretion of the cortisol derivatives, 18-oxocortisol and 18-hydroxycortisol are believed to be regulated by ACTH and to a lesser degree by the renin-angiotensin system. Plasma concentrations of 18-oxocortisol and 18-hydroxycortisol were measured during the simultaneous activation of the renin-angiotensin system and inhibition of ACTH secretion. Five healthy male subjects consuming a sodium diet ad libitum were studied. Blood was drawn at 0800 h after 1 h in the supine position. In the first set of experiments, the subjects remained in the supine position from 0800 to 1000 h with or without the oral administration of 2 mg dexamethasone at 0800 h. In the second set of experiments the subjects were placed in the upright position after drawing the 0800 h sample. The subjects were studied with and without dexamethasone administered at 0800 h. Blood was drawn again at 1000 h. Plasma levels of 18-oxocortisol, 18-hydroxycortisol, ACTH, plasma renin activity (PRA), cortisol, aldosterone and 18-hydroxycorticosterone were measured by radioimmunoassay. None of these parameters changed during the 2 h in the supine position. 18-Oxocortisol, 18-hydroxycortisol, aldosterone, 18-hydroxycorticosterone and PRA increased, but ACTH and cortisol did not change when the subjects were placed in the upright position. After dexamethasone administration, 18-oxocortisol, 18-hydroxycortisol, cortisol, aldosterone and 18-hydroxycorticosterone decreased in the supine position and no increase occurred in 18-oxocortisol, 18-hydroxycortisol and 18-hydroxycorticosterone in the upright position. PRA and aldosterone increased and ACTH and cortisol decreased in these subjects. 18-Oxocortisol and 18-hydroxycortisol were more dependent on ACTH regulation and less on the renin-angiotensin system than aldosterone.

18-Hydroxycorticosterone↗
PubMed1993

Limitation of stunning in dog myocardium by nucleoside and nucleotide mixture, OG-VI.

BACKGROUND: OG-VI is a nucleoside-nucleotide solution composed of 30 mM inosine, 30 mM cytidine, 30 mM sodium 5'-guanylate, 22.5 mM uridine, and 7.4 mM thymidine. It is expected to enhance the efficacy of intravenous hyperalimentation in surgically stressed patients. One of the main causes of ischemic myocardial damage is loss of adenine nucleotides from heart cells. The aim of the present study, therefore, was to examine the effect of OG-VI on myocardial mechanical function and energy metabolism in stunned myocardium. METHODS: Pentobarbital-anesthetized dogs were subjected to 20 min ligation of the left anterior descending (LAD) coronary artery, followed by reperfusion for 30 min. OG-VI at 0.1 or 0.2 ml/kg/min or saline was infused from the left femoral vein throughout the experiment. The tissue levels of high-energy phosphates in the hearts were determined after 30 min reperfusion. RESULTS: LAD flow, first derivative of left ventricular pressure (LVdp/dt), and segment function were increased by OG-VI in a dose-dependent manner. OG-VI infusion resulted in a significant improvement in LVdP/dt and segment shortening in the ischemic/reperfused myocardium compared with saline infusion. The levels of segment shortening with saline, 0.1, and 0.2 ml/kg/min OG-VI after reperfusion for 30 min were -0.3, 75, and 82% of the preligation levels, respectively. The tissue level of adenosine triphosphate (ATP) after reperfusion in OG-VI-infused animals was significantly higher than that in saline-infused animals. CONCLUSION: OG-VI has a positive inotropic action, and its infusion results in a marked cardioprotective effect in stunned myocardium associated with the restoration of tissue ATP level.

Animals↗
PubMed1993

Ca(2+)-dependent stimulatory effect of pituitary adenylate cyclase-activating polypeptide on catecholamine secretion from cultured porcine adrenal medullary chromaffin cells.

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates catecholamine secretion from cultured porcine adrenal medullary chromaffin cells in a dose-dependent manner with the half-maximal and maximal doses of 30 nM and 1 microM, respectively. Either removal of extracellular Ca2+ or addition of Gd3+, an inorganic Ca2+ channel blocker, very potently inhibits PACAP-induced catecholamine secretion. Both nicardipine (1 microM) and methoxyverapamil (1 microM), blockers of voltage-dependent Ca2+ channels, are also effective in inhibiting PACAP-induced catecholamine secretion. When the intracellular free Ca2+ concentration ([Ca2+]i) is measured in a fura 2-loaded single chromaffin cell, PACAP is found to cause a sustained increase in [Ca2+]i by mobilizing Ca2+ from both extra- and intracellular pools. It is also found that PACAP stimulates the production of inositol phosphates in a dose-dependent manner, which is not abolished by removal of extracellular Ca2+ unlike the case of nicotine. PACAP increases cAMP content in chromaffin cells in a dose-dependent manner. Removal of extracellular Ca2+ enhances PACAP-induced cAMP production but strongly inhibits PACAP-induced catecholamine secretion. Pretreatment of cells with adenosine-3':5'-monophosphothioate, cyclic, Rp-isomer, a cAMP antagonist, does not block PACAP-induced catecholamine secretion. The addition of forskolin or 3-isobutyl-1-methylxanthine does not enhance the PACAP-induced catecholamine secretion. These results indicate that PACAP activates voltage-dependent Ca2+ channels and phospholipase C as well as adenylate cyclase in cultured porcine adrenal medullary cells and strongly suggest that PACAP-induced catecholamine secretion is mainly mediated by activation of voltage-dependent Ca2+ channels.

Adrenal Medulla↗
PubMed1993

Protective effect of dihydroheptaprenol in combination with vaccine to experimental Actinobacillus pleuropneumoniae infection in guinea pigs and pigs.

We investigated the effects of dihydroheptaprenol (DHP) on resistance of guinea pigs and pigs inoculated with Actinobacillus pleuropneumoniae (Apn) vaccine to subsequent challenge with Apn. Guinea pigs with complement-fixation (CF) antibody titers of 1:8 and 1:16 after intramuscular (i.m.) inoculation with inactivated Apn vaccine showed enhanced resistance to intraperitoneal (i.p.) infection with a homologous Apn strain (5 x 10(10) CFU/animal) when injected with DHP (20 mg/kg, i.m.) on the day before infection. The survival rates of the control, vehicle (lecithin solution without DHP), and DHP groups were 33%, 37%, and 63%, respectively, and that of the DHP group was significantly higher than the rates of the other groups (P < 0.05). Pigs with CF antibody titers of 1:8 and 1:16 after i.m. inoculation with inactivated Apn vaccine showed enhanced resistance to intratracheal infection with 5 x 10(10) CFU of Apn when injected with DHP (1, 2.5, or 5 mg/kg, i.m.) on the day before infection. The survival rates of the control, vehicle, DHP 1 mg/kg, DHP 2.5 mg/kg, and DHP 5 mg/kg groups were 37%, 38%, 47%, 60%, and 73%, respectively, and pigs given DHP at a dose of 5 mg/kg showed a significantly higher survival rate than the vaccinated control pigs (P < 0.05). The protective effect of DHP in vaccinated guinea pigs and pigs suggests that phagocytosis and bactericidal activity may be enhanced by this agent, depending on some opsonification effect on Apn antibody.

Actinobacillus Infections↗
PubMed1993

Adrenal myelolipoma: comparison of diagnostic imaging and pathological findings.

Myelolipoma of the adrenal gland is a rare, benign, nonfunctioning lesion consisting of fat and bone marrow elements in varying proportions. This tumor is commonly asymptomatic and usually discovered during various diagnostic imaging examinations performed for unrelated diseases. If a primary malignant or metastatic adrenal tumor cannot be excluded, ultrasound- or computed tomography-guided needle biopsy of the tumor is necessary. We report a case of adrenal myelolipoma associated with advanced gastric carcinoma and compare the diagnostic imaging findings with the pathological findings of the adrenal myelolipoma.

Adenocarcinoma↗
PubMed1993

[Alterations of skeletal muscle metabolism in patients with congestive heart failure].

The metabolism of the skeletal muscles during exercise and recovery was investigated using phosphocreatinine (PCr) and inorganic phosphate (Pi) in patients with chronic heart failure. PCr/Pi ratio, which is closely related to the ATP/ADP ratio, and the pH were measured by 31P-magnetic resonance spectroscopy (31P-MRS) during and after forearm exercise in 9 patients with chronic heart failure, 11 patients with chronic lung disease, and 8 normal subjects. Exercise and recovery scans were recorded every minute for 4 min. The PCr/Pi ratio in patients was lower during the recovery period and significantly lower 3 and 4 min after exercise than in normal subjects. The pH values after exercise were lower in patients, although not significantly. The PCr/Pi ratio 4 min after exercise in patients was not correlated with parameters of cardiac function or arterial and mixed venous oxygen tension. Nutritional parameters did not vary statistically among the groups. Metabolic abnormalities may be present in the skeletal muscles of patients' group, which are not due to undernutrition, possibly as a result of exercise deconditioning and probably a shift in fiber distribution (type I decreases, type IIb increases) and a decrease in oxidative capacity.

Aged↗
PubMed1993

[Interaction between vecuronium and pancuronium].

Interaction between vecuronium bromide (VB) and pancuronium bromide (PB) with regard to a change in duration of action was investigated in 32 elective surgical patients divided into four groups. Initial and supplemental drugs were as follow; group I: VB-->VB, group II: PB-->VB, group III: VB-->PB, group IV: PB-->PB. The muscle response was quantified electromyographically. Anesthesia was induced with thiopental. VB or PB 0.08 mg.kg-1 (initial dose) was given to facilitate endotracheal intubation. Anesthesia was maintained with 66% nitrous oxide and 2% sevoflurane in oxygen. Supplemental dose (0.015 mg.kg-1) of the muscle relaxants was administered at 10% recovery of twitch height. Duration of action was defined as the interval between administration and 10% recovery. Duration of action of supplemental doses of VB was significantly longer in group II than in group I. That of PB was significantly shorter in group III than in group IV. Therefore, it should be noticed that duration of action of supplemental relaxant is largely modified by the initial one.

Adult↗
PubMed1993

[Adult case of bronchial asthma induced by chironomid midges].

A 48-year-old woman who was diagnosed to have bronchial asthma induced by chironomid midges is reported. In spring of 1985, massive growth of chironomid midges occurred in the river beside her house. Since then, moderate growth has occurred in every spring or summer. She had wheezing attacks every May or June since June 1986. On May 2, 1991, she was hospitalized because of exacerbation of wheezing and dyspnea. Wheezing attacks were improved by appropriate medical treatment during hospitalization. Examination was performed during the state of stable clinical symptoms. RAST scores to Chironomus thummi thummi (CTT) and Chironomus plumosus (CP) were 4 and 3, respectively. Allergic skin reaction showed the threshold dilution of CP of 10(-6). CP skin test concomitantly provoked a mild acute asthma attack. The midges found swarming around her house were identified as Chironomus nippodorsalis. According to her clinical history and allergic skin reactions followed by acute asthmatic attack, this patient was diagnosed to have bronchial asthma induced by chironomid midges. Chironomid midge can be one of the inhalant allergens in adults.

Adult↗
PubMed1993

[Effects of cilostazol, a cyclic AMP phosphodiesterase inhibitor, on pulmonary vascular tone].

We examined the effect of Cilostazol, a cyclic AMP phosphodiesterase inhibitor, rat isolated pulmonary arterial ring tone. Cilostazol dilated pulmonary arterial rings pre-contracted with 10(-6) M phenylephrine in a dose-dependent manner (ED50 3.00 x 10(-6) M). This vasodilatory effect of Cilostazol was not affected by pretreatment with meclofenamate (10(-5) M), mechanical endothelium denudation, methylene blue (10(-5) M) or nitro-L-arginine (2 x 10(-4) M). The vasodilatory effect of Cilostazol on rat thoracic aortic rings was stronger than that on rat pulmonary arterial ring (ED50 1.89 x 10(-6) M). Cilostazol (10(-6) M-10(-4) M) inhibited hypoxic contraction of rat pulmonary rings in a dose-dependent manner. Our experimental data indicated that Cilostazol caused vasodilation regardless of vascular endothelium function and inhibited hypoxic contraction due to inhibition of cyclic AMP phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1993

[Measurements of serum pituitary hormones and dynamic tests to evaluate the pituitary functions].

Hormones produced by the anterior pituitary have conventionally been measured in the serum by radioimmunoassays (RIA), whereas more sensitive immunoradiometric assays (IRMA) have now been developed and are replacing RIA. Dynamic tests (stimulatory tests and suppression tests) rather than single and random determinations are often important tools in the study of pituitary functions. Stimulatory tests (such as glucagon plus propranolol test for growth hormone and water deprivation test for arginine-vasopressin) are used to evaluate hypofunction and suppression tests (such as dexamethasone suppression test for adrenocorticotrophic hormone) are used to investigate hyperfunction. This chapter, mainly dealing with representative dynamic tests, describes test protocols and how to interpret test results.

Adrenocorticotropic Hormone↗
PubMed1993

[Resuscitation from experimentally induced hemorrhagic shock with hypertonic saline (effects on thoracic duct lymph flow and tissue oxygen tension)].

We compared the effect of hypertonic salt solution (7.2%, HS) with that of normal saline (NS) and lactated Ringer's solution (LR) for the treatment of hemorrhagic shock. We monitored hemodynamic parameters, thoracic duct lymph flow, and tissue oxygen tension over 3 hours after hemorrhage. Twenty-seven anesthetized mongrel dogs (0.5% halothane) were bled to an aortic pressure of 60 mmHg for 90 min following 40 mmHg for 30 min and then they were resuscitated with each solution. In NS group, the volume transfused was twice the bled volume, and in other two groups, each solution was transfused providing equal amounts of sodium as NS group. We found that hemodynamics were restored in HS group as well as in other two groups. On the other hand, thoracic duct lymph flow and tissue oxygen tension of renal cortex and liver increased significantly over other two groups. We conclude that small volume resuscitation with 7.2% NaCl may be effective in the initial treatment of hemorrhagic shock from the view of tissue circulation in vital organs.

Animals↗
PubMed1993

[Home intermittent negative pressure ventilation in a case of chronic respiratory failure due to old tuberculous pleuritis].

A 64-year-old male with a history of tuberculous pleuritis at age 29 had received home oxygen therapy since age 58 because of chronic respiratory failure. He was admitted with symptoms of dyspnea at rest and myoclonus at age 62. Because CO2 narcosis occurred twice, we performed intermittent negative pressure ventilation (INPV) after short-term positive pressure ventilation with transnasal intubation. He has received INPV for 7 hours every day at his home for 20 months without acute exacerbation of respiratory failure, and his activity of daily life subsequently improved. In conclusion, INPV seems to be useful for patients with chronic hypercapnic respiratory failure due to lung disease.

Chronic Disease↗
PubMed1993

[Advances in diagnostic procedures for detection of pheochromocytoma].

Pheochromocytoma arises from chromaffin tissue, usually in the adrenal medulla, and is a cause of curable hypertension. In most cases, clinical acumen alone is not sufficient to diagnose pheochromocytoma. Therefore, the diagnosis of this disorder has become almost totally dependent on laboratory test results. The most widely used biochemical procedures for detection of pheochromocytoma are measurements of urinary catecholamines or their metabolites, such as vanillylmandelic acid (VMA) or total metanephrine (MN). Traditional spectrophotometric and fluorometric methods for urinary catecholamines and their metabolites are being replaced by highly sensitive and selective chromatographic methods. Plasma noradrenaline and adrenaline measurements are of additional diagnostic value in determining recent catecholamine release and response to clonidine suppression. For either urine or plasma measurements, appropriate patient preparation, sample collection and method validation along with an understanding of the variable pattern of catecholamine secretion and metabolism in pheochromocytoma are essential. Localization of tumors is important for the surgeon and is accomplished by CT scan, 131I-metaiodobenzylguanidine scintiscans or abdominal aortography.

Adrenal Gland Neoplasms↗
PubMed1993

Tauroursodeoxycholate and tauro-beta-muricholate exert cytoprotection by reducing intrahepatocyte taurochenodeoxycholate content.

Cytoprotection by tauroursodeoxycholic acid and tauro-beta-muricholic acid against taurochenodeoxycholic acid-induced toxicity was examined with reference to intracellular bile acid content in primary cultured rat hepatocytes. In comparison with levels in the group administered taurochenodeoxycholic acid 1 mmol/L alone, lactate dehydrogenase levels in the culture medium decreased significantly in groups simultaneously administered taurochenodeoxycholic acid 1 mmol/L and tauroursodeoxycholic acid 0.5 to 2 mmol/L or tauro-beta-muricholic acid. Results of the trypan blue uptake test indicated that the lactate dehydrogenase release was indeed caused by cell damage. After the administration of tauroursodeoxycholic acid 2 mmol/L or tauro-beta-muricholic acid 2 mmol/L, intracellular taurochenodeoxycholic acid content was consistently reduced to half of that after administration of taurochenodeoxycholic acid alone. Simultaneous administration of dibutyl cyclic AMP also reduced intracellular taurochenodeoxycholic acid content and lactate dehydrogenase release. Being rinsed with tauroursodeoxycholic acid and tauro-beta-muricholic acid after being precultured in taurochenodeoxycholic acid 1 mmol/L also markedly reduced their taurochenodeoxycholic acid content. Taurocholic acid caused limited reduction of intracellular taurochenodeoxycholic acid but not suppression of lactate dehydrogenase release. Taurodehydrocholic acid showed no reduction of taurochenodeoxycholic acid content and no decrease of lactate dehydrogenase release. Although only small amounts of tauroursodeoxycholic acid or tauro-beta-muricholic acid were found to accumulate in hepatocytes, taurocholic acid increased as if replacing taurochenodeoxycholic acid. The results suggest that tauroursodeoxycholic acid or tauro-beta-muricholic acid may exert cytoprotective effects by lowering intracellular taurochenodeoxycholic acid levels associated with their optimal hydrophilicity.

Animals↗
PubMed1992

Different antigenic nature in apparently healthy women with high serum CA 125 levels compared with typical patients with ovarian cancer.

BACKGROUND: CA 125 is a representative ovarian cancer-associated antigen defined by monoclonal antibody OC125. Recently, monoclonal antibodies were produced (designated 130-22 and 145-9) that were reactive with CA 125 but bound to a separate epitope named CA 130. There was a close correlation between serum CA 125 and CA 130 values in most instances. However, among more than 8000 serum samples, 5 apparently normal women had high serum CA 125 values, despite having normal CA 130 values. In this study, the antigenic nature of these five women was investigated. METHODS: Using gel chromatography, the molecular masses of CA 125 and CA 130 were estimated that were found in the five women with false-positive CA 125 values. The sera were examined using double-determinant assays combining iodine-125-labeled OC125 or iodine-125-labeled 130-22 with OCI25-coated or 145-9-coated beads. RESULTS: The molecular masses of both CA 125 and CA 130 were estimated as greater than 1000 kilodaltons (KD); the CA 130 mass from one of the five women with an abnormal CA 125 level was approximately 200 KD using gel chromatography. Using the double-determinant assays that combined iodine-125-labeled OC125 or iodine-125-labeled 130-22 with OC125-coated or 145-9-coated beads, high radioactivity was found only in the homologous assay using iodine-125-labeled OC125 with OC125-coated beads. These results suggest that the antigenic nature of CA 125 found in apparently healthy women differs from that found in patients with ovarian cancer and that CA 130 epitopes are not present. CONCLUSIONS: Measurement of serum CA 130 concentrations may be useful for excluding women with falsely elevated CA 125 values.

Acrylic Resins↗
PubMed1992

Microtubule-independent choleresis and anti-cholestatic action of tauroursodeoxycholate in colchicine-treated rat liver.

In order to cast light on the anti-cholestatic and cytoprotective properties of ursodeoxycholic acid (UDCA), intrahepatic transport and secretion of bile salts and biliary phospholipids were investigated by using isolated perfused livers from colchicine-pretreated rats. Administration of taurocholic acid (TCA) after colchicine pretreatment induced marked cholestasis. Tauroursodeoxycholic acid (TUDCA) treatment, in contrast, was associated with maintenance of bile flow, with excretion rates of bile acids and phospholipids similar to those in control animals. Furthermore, TCA-induced cholestasis in colchicine-treated rat livers was clearly decreased by co-administration of TUDCA. Although simultaneous addition of UDCA also showed slight improvement, with or without taurine pre-treatment, biliary bile-salt analysis also showed that cholestasis was markedly remitted as the excretion of taurine-conjugated UDCA was increased. The results suggest that the cytoprotective and anti-cholestatic effects of TUDCA may be linked to action at the intrahepatocyte level, represented by mild detergent effects on organelle lipids and preservation of intracellular transport even under microtubule-dysfunctional conditions. In addition, it was indicated that cytoprotective effects of UDCA may also be exerted after its conjugation with taurine inside hepatocytes.

Animals↗