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Biomedical subjects

H Tamai

Publications and source records attributed to H Tamai.

At least 181 records · Page 10Linked to original sources
PubMed1993

Direct evidence for nitric oxide stimulation of electrolyte secretion in the rat colon.

Nitric Oxide (NO) is synthesized in the intestinal tract and may serve as a physiological regulator of intestinal ion transport and/or a pathophysiologic mediator of secretory diarrhea associated with inflammatory mucosal diseases. Indirect approaches, employing inhibitors of nitric oxide synthase or compounds capable of donating NO in solution, have been used to demonstrate the effects on gastrointestinal muscle and the mucosa. To determine directly whether nitric oxide itself is capable of stimulating electrolyte secretion we mounted muscle-stripped rat distal colon in Ussing chambers and monitored short-circuit current (Isc), as an indicator of effects on mucosal ion transport. Comparisons were made to sodium nitroprusside (SNP). NO and SNP stimulated concentration-dependent (0.1 microM to 100 microM) increases in Isc, with NO being more potent than SNP. The EC50 for NO was approximately 8 microM compared to a value < 20 microM for SNP. The response to NO was immediate. In contrast, SNP required a mean lag-time of 41 +/- 4 seconds, and a significantly longer time was required for SNP to reach its maximum effect. The response to both of these agonists was blocked by bumetanide, indicating that they were stimulating a chloride ion secretory response. The cyclooxygenase inhibitor piroxicam, the neurotoxin tetrodotoxin and the inhibitor of guanylate cyclase, methylene blue, all inhibited the response to both agonists. These studies demonstrate that NO itself can stimulate chloride secretion by the rat colonic mucosa through a prostaglandin-dependent, and partially neural mechanism that may involve guanylate cyclase.

Animals↗
PubMed1993

Nutritional status of antioxidant vitamins (A, E, and beta-carotene) in elderly Japanese.

The nutritional status with respect to vitamins A and E, and beta-carotene was examined in elderly Japanese subjects in two institutions at Osaka and Kyoto. Only the plasma vitamin E level has been determined in the majority of previous investigations. In this study, vitamin E levels were determined in red blood cells (RBCs), platelets (PLT), mononuclear cells (MN), polymorphonuclear cells (PMN), and buccal mucosal cells (BMC), using HPLC with electrochemical detection. Alpha-tocopherol levels in plasma and RBCs did not differ between elderly and young adults, while those in PLT, MN, and BMC were lower in the elderly. Thus, the vitamin E status of elderly Japanese individuals appears to be inadequate of the cellular levels. The daily vitamin E intake of the elderly subjects was below the recommended dietary allowance for the Japanese population. Plasma levels of retinol and beta-carotene were also assessed. The vitamin A status did not differ between elderly and young adults on the basis of the levels of retinol and retinol-binding protein (RBP). The daily intake of retinol (as retinol equivalent) by the elderly subjects was more than 2,000 IU. With respect to beta-carotene, there was a large sex difference (female > male), which was more prominent in the young adults and became smaller in the elderly. This sex difference was partly attributable to a difference in plasma total lipids. No clear age-related trend was noted.

Adult↗
PubMed1993

[Measurement of vitamin E from biological samples].

Recent advances in HPLC have enabled to measure small amounts of tocopherols in biological samples. A fluorescence detector is usually used for detection of tocopherols, however we have determined tocopherols of blood samples by an electrochemical detection (ECD). This ECD method is 1,000 times more sensitive than conventional fluorescence methods, and is suitable for detection of small amounts of tocopherols of blood cells. In this report, preparation and extraction methods from blood samples are described. Preparation of blood to separate plasma, platelets, mononuclear cells, and polymorphonuclear cells is performed using a density-gradient method. Extraction of tocopherols usually involves saponification using ethanolic solution of potassium hydroxide.

Chromatography, High Pressure Liquid↗
PubMed1992

Induction of colitis in rats by 2-2'-azobis(2-amidinopropane) dihydrochloride.

Reactive oxygen metabolites (ROM) may play a role in the pathophysiology of inflammatory bowel disease (IBD) and ischemia-reperfusion-induced intestinal injury. Although there are many reports of intestinal mucosal injury associated with neutrophil-derived ROM, free radicals themselves have not been reported to induce intestinal mucosal injury. We administered intrarectally 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) to rats, an azo compound that generates free radicals in vitro. Acute mucosal injury was assessed histologically by light microscopy and biochemically by myeloperoxidase (MPO) activity. Intrarectal administration of AAPH (60, 90, 150 mg/kg) caused erythema, edema, and histologically verifiable mucosal inflammation. MPO activity was increased 9- to 18-fold above the control level. The levels of thiobarbituric acid (TBA) reactants and sulfhydryls (SH) were significantly (P less than 0.01) increased and decreased, respectively, by 90 mg/kg AAPH. Sulfasalazine, 5-aminosalicylic acid, the LTB4 receptor antagonist SC-41930, and the antioxidant glutathione prevented the inflammation. This model of mucosal inflammation may be useful in evaluating new therapeutic agents for the treatment of IBD.

Amidines↗
PubMed1992

Determination of beta-carotene in plasma, blood cells and buccal mucosa by electrochemical detection.

The beta-carotene concentrations in plasma, blood cells and buccal mucosal cells were determined by high-performance liquid chromatography with electrochemical detection. This method was 1,000 times more sensitive than the conventional spectrophotometric method. Polymorphonuclear cells and red blood cells had lower beta-carotene levels than the other cells. After oral administration of 580 mg/day of all-trans beta-carotene to human male volunteers for a week, the beta-carotene concentrations in all cell types increased at least several times above the original levels.

Adult↗
PubMed1992

HLA-A and DPB1 loci confer susceptibility to Graves' disease.

To investigate HLA-linked genetic factors involved in the pathogenesis of Graves' disease, 76 patients and 317 healthy controls in the Japanese population were examined for HLA-A, B, C, DR, and DQ specificities by serologic typing and for HLA-DPB1 alleles by DNA typing by using the PCR-SSOP method. The frequencies of HLA-A2, B46, Cw11, and DPB1*0501 were increased and those of HLA-A24, B7, Bw52, and DR1 were decreased in the patients. The increased frequencies of HLA-A2 and DPB1*0501 in the patients were statistically significant when the corrected p value (pc) was applied (pc < 0.02 and pc < 0.002, respectively). ORs for a risk to develop the disease were calculated among individuals positive for DPB1*0501 and/or HLA-A2, and the highest OR (10.5) was observed in individuals possessed both DPB1*0501 and HLA-A2. This observation suggests a synergic involvement of a HLA class II allele (DPB1*0501) and an HLA class I allele (HLA-A2) in the pathogenesis of Graves' disease.

Adolescent↗
PubMed1992

Clinical events in association with timing of intraventricular hemorrhage in preterm infants.

To ascertain whether any routine practices or clinical manipulations in a neonatal intensive care unit could induce intraventricular hemorrhage (IVH) in preterm infants, we performed ultrasonic monitoring of the germinal layer continuously for 48 hours in 33 extremely premature infants with respiratory distress. Intraventricular hemorrhage developed in 16 of these infants. In four infants the timing of the germinal layer hemorrhage was confirmed with ultrasonic monitoring. Three of the four cases were apparently associated with clinical events occurring at the moment of IVH: manual ventilation for improvement of hypercapnia associated with primary pulmonary hypertension of the newborn; correction of hyperkalemia, which was causing an arrhythmia, with administration of calcium gluconate and sodium bicarbonate; and administration of surfactant-TA to improve respiratory failure caused by pulmonary hemorrhage. In these three infants it appeared that one of the basic factors inducing IVH might be an increase in blood pressure with or without hypercapnia, causing cerebral reperfusion after ischemic damage of the germinal layer.

Blood Pressure↗
PubMed1992

Alterations in endothelium-associated proteins and serum thyroid hormone concentrations in anorexia nervosa.

Plasma concentrations of endothelium-associated proteins (EAP) (plasma fibronectin (PFN), angiotensin-converting enzyme, factor VIII-related antigen (F VIII-R:Ag)) and tissue plasminogen activator and serum thyroid hormone concentrations were studied in nine patients with anorexia nervosa (AN), before and after weight gain. Before weight gain (-35.9 (SE 2.3)% of standard body-weight) PFN was significantly reduced and F VIII-R:Ag was significantly increased in AN patients compared with the concentrations in control subjects (211.5 (SE 14.9) v. 274.7 (SE 16.6) micrograms/ml, P < 0.05; 129.2 (SE 14.1) v. 88.2 (SE 9.7) %, P < 0.05 respectively). Serum triiodothyronine (T3) and free T3 levels were also significantly lower before weight gain in AN patients (0.85 (SE 0.07) v. 1.53 (SE 0.08) nmol/l, P < 0.001; 2.57 (SE 0.23) v. 5.31 (SE 0.34) pmol/l, P < 0.001 respectively), although serum thyroxine (T4), free T4, and thyrotropin concentrations were within the normal range throughout the study periods. Following weight gain, PFN and F VIII-R:Ag concentrations normalized as did the thyroid hormone levels. The incremental changes in PFN levels correlated significantly with those in serum thyroid hormone concentrations (T3, r 0.79, P < 0.01; free T3, r 0.84, P < 0.01). These findings suggest that PFN levels may be directly related to serum T3 concentrations in AN patients.

Adult↗
PubMed1992

The role of thyroid stimulating antibody (TSAb) in the thyroid function of patients with post-partum hypothyroidism.

OBJECTIVE: We investigated the association between thyroid function and the biological activities of thyroid stimulating antibodies (TSAb) and thyroid stimulation blocking antibodies (TSBAb) in patients with post-partum hypothyroidism. DESIGN: A prospective study. PATIENTS: We studied 25 patients with post-partum hypothyroidism who visited our thyroid clinic during the period from 1985 to 1990. MEASUREMENTS: We measured TSH binding inhibitory immunoglobulin (TBII) and TSAb activity at the initial presentation of each of the 25 patients. Women found to have elevated TSAb activity were followed up. Upon finding negative TSAb activity along with positive TBII activity in the serum at the initial presentation, we measured TSBAb activity. Women found to have elevated levels of TSBAb at the initial presentation were also followed up. RESULTS: Elevated TBII activity was found in six of the 25 patients, as was high TSAb activity (205-2651%, normal 55.0-145.0%) in five of these six and in one other patient at the initial presentation. Markedly elevated TSBAb activity (89%) was found in one TBII positive patient. We were able to follow up serially five TSAb positive patients and the TSBAb positive patient over periods ranging from 11.5 to 26.5 months post-partum. The maximal value of TSAb activity was observed at the initial presentation in all TSAb positive patients, following which the activities gradually decreased. One of these patients developed Graves' hyperthyroidism associated with high TSAb activity (1223%) at 10.5 months post-partum. One of the other patients was restored to euthyroid with elevated TSAb activity (279%), but thereafter developed hypothyroidism in conjunction with the disappearance of TSAb activity at 26.5 months post-partum. In the other two patients, normalization of thyroid function was observed with elevated TSAb activity. Thereafter, thyroid function remained within the normal range even with the disappearance of TSAb activity. In the other patient, normalization of thyroid function was observed at 11.5 months post-partum, 3 months after the disappearance of TSAb activity. In the TSBAb positive patient, TSBAb activity decreased to 21% by 17.5 months post-partum associated with normalization of thyroid function. CONCLUSION: The present study demonstrates the presence of elevated levels of TSAb activity in some patients with post-partum hypothyroidism. In these patients, Graves' hyperthyroidism may be induced by TSAb activity, and hypothyroidism may reoccur with the disappearance of the TSAb activity. Furthermore, post-partum hypothyroidism may be due to increased TSBAb activity in some patients.

Antibodies↗
PubMed1992

Pancreatic B-cell functioning after intravenous glucagon administration in anorexia nervosa.

Abnormal glucose tolerance is often found in patients with anorexia nervosa (AN). We attempted to evaluate pancreatic B-cell functioning after intravenous glucagon administration. Fourteen patients with the restricting type of AN (percentage of ideal body weight 71.5 +/- 1.6%, mean +/- SE) and 6 patients with the bulimic type of AN (77.0 +/- 3.0%) were studied. After an overnight fast, glucagon (0.02 mg/kg) was injected i.v. into all subjects and 6 normal controls. Blood samples were obtained at 0, 5, 30, 60, 90 and 120 min to measure blood glucose (BS), serum insulin (IRI) and C-peptide (CPR). The same tests were repeated in 8 patients with restricting AN after therapy and restoration of body weight (85.9 +/- 1.0% of ideal body weight). BS responses did not differ among the groups. Peak serum levels (5 min) of both IRI and CPR in restricting AN patients were significantly lower than those in bulimic AN patients and in normal controls. BS, IRI and CPR concentrations did not change significantly following restoration of body weight. Pancreatic B-cell dysfunction after glucagon administration was observed in restricting AN patients and the abnormality persisted after short-term weight restoration.

Adult↗
PubMed1992

Aldosterone responses to angiotensin II in anorexia nervosa.

Patients with anorexia nervosa (AN) tend to have renin-angiotensin-aldosterone (RAA) abnormalities caused by abnormal behaviors such as strict dieting, fasting, vigorous exercise, self-induced vomiting and abuse of laxatives and/or diuretics. Adrenal responsiveness to angiotensin II (A II) was studied in 13 AN patients before and after therapy and in 6 normal sex- and age-matched controls: adrenal responses to postural change (1 h of walking following 1 h in a supine position) and to exogenous A II injection (A II: 10 ng/kg/min intravenous infusion for 30 min). The 24-h urine sodium concentration was significantly lower in AN patients before therapy than after therapy. Plasma aldosterone secretory response to A II was significantly higher in AN patients before therapy in both postural change and exogenous A II injection tests compared with after therapy response and that of controls. On the other hand, there was no significant difference in adrenal response to postural change or to exogenous A II between AN patients after therapy and controls. In conclusion, increased A II sensitivity caused by chronic sodium deficiency in AN patients normalized over time as the patients recovered.

Adult↗
PubMed1992

Ca-mediated stimulation of Cl secretion by reactive oxygen metabolites in human colonic T84 cells.

Monochloramine (NH2Cl), a granulocyte-derived reactive oxygen metabolite (ROM), increases short-circuit current (Isc) in cultured T84 monolayers in a concentration-dependent manner up to nonlethal concentrations of 75 microM. Isc increases slowly after NH2Cl, reaching a peak value of 18 +/- 2 microA/cm2 20 min after addition. The Isc changes are persistent (lasting over 20-30 min), depend on medium Cl, and are inhibitable with bumetanide. 36Cl flux studies demonstrated that NH2Cl increases serosa-to-mucosa flux of Cl without changing mucosa-to-serosa flux, consistent with stimulation of electrogenic Cl secretion. Isc responses to NH2Cl, but not PGE2, are dependent on medium calcium. As demonstrated in fura-2-loaded T84 cells, NH2Cl increases free cytosolic calcium by influx of extracellular Ca2+ and by release of Ca2+ from endogenous stores. However, NH2Cl had no effect on phosphatidylinositol metabolism or cyclic nucleotide levels. We conclude that ROM directly stimulate electrolyte secretion, an effect in part mediated by increases in cytosolic Ca2+, possibly through increasing Ca2+ permeability of cellular membranes.

Biological Transport↗
PubMed1992

Effect of alpha-tocopherol on oxidative hemolysis, as evaluated by impedance measurement.

Using a hypoxanthine-xanthine oxidase (HX-XOD) reaction system, the effect of vitamin E (VE) on oxidative membrane injury was studied by the impedance method. Both VE-sufficient and VE-deficient erythrocytes showed an elevation of low frequency permittivity in the early phase of reaction. In the later phase of reaction, VE-sufficient erythrocytes showed a sustained elevation in permittivity, while VE-deficient erythrocytes showed a decrease in permittivity with time. These changes consisted with the process of hemolysis in the HX-XOD system. The similarity of early phase change between VE-sufficient and VE-deficient erythrocytes indicates that the HX-XOD system exerted a similar effect on both erythrocytes in the early phase. The difference in changes of later phase between the two types of erythrocytes suggests that VE suppressed the reduction in permittivity. When the results were analyzed by the Pauly-Schwan's theory based on the assumption that erythrocytes are spherical, the product of VE-deficient or VE-sufficient erythrocyte size (R) and membrane capacity (Cm) showed a change similar to that in permittivity.

Algorithms↗