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Biomedical subjects

T Sakata

Publications and source records attributed to T Sakata.

At least 217 records · Page 12Linked to original sources
PubMed1996

Genetic characterization of protein C deficiency in Japanese subjects using a rapid and nonradioactive method for single-stand conformational polymorphism analysis and a model building.

We studied the molecular basis of protein C deficiency in 28 Japanese families including 4 asymptomatic families. Two showed a decreased level of function with a normal antigen concentration consistent with type II protein C deficiency and the remaining 26 showed type I deficiency with decreases in both function and antigen level. All the exons and intron/exon junctions of the protein C gene were studied using a strategy combining polymerase chain reaction (PCR) amplification and rapid nonradioactive single-strand conformational polymorphism (SSCP) analysis. The PCR-amplified fragments with aberrant migration on SSCP analysis were sequenced. We identified 11 missense mutations, 1 nonsense mutation, 2 neutral polymorphisms, 1 frameshift deletion, 1 inframe deletion, and 1 splice site mutation. We also identified two different rare mutations in the 5'-untranslated region in the protein C gene that may be responsible for the phenotype. Of these molecular defects, ten were novel. From the results of genetic analysis of 47 Japanese families with protein C deficiency reported in this and previous studies, Phe139Val and Met364Ile substitutions and a G8857 deletion were only found in Japanese subjects and seem to be a founder effect. In contrast, Arg169Trp and Val297Met substitutions, both occurring at CG dinucleotides, were commonly observed in not only Japanese but also Western populations, indicating that these are hot spots for mutation in the protein C gene. These molecular defects were found in 22 families in total, accounting for 47% of Japanese families with protein C deficiency. The structural models of the second EGF and protease domains of activated wild-type and mutant human protein C suggest a possible substrate binding exosite on two loops; one from amino acid position 349 to 357 and the other from position 385 to 388, both of which are close to each other in the three-dimensional model.

Amino Acid Sequence↗
PubMed1996

Two cases of intrascrotal liposarcoma.

Liposarcomas in the scrotum are relatively rare and only 40 cases have previously been reported in Japan. The inside wall of the scrotum is an unusual origin and we report here two cases arising at this site that have been followed for 21 and 40 months, respectively, after surgical resection. Case 1: the patient was a 24-year-old male who noticed a left intrascrotal mass which was histologically demonstrated to be a myxoid type liposarcoma. Case 2: the patient was a 66-year-old male who had the complaint of a left intrascrotal swelling. He underwent radical orchiectomy and histologic examination of the resected tumor revealed a well-differentiated type of liposarcoma. These two cases are the 41st and 42nd intrascrotal liposarcomas reported in Japan.

Adult↗
PubMed1996

[Chronic pulmonary nocardiosis with eosinophilia in an immunocompetent host].

A 75-year-old man who worked at a horse racing track, had an abnormal shadow on a chest radiography. He had a history of dilated cardiomyopathy and mitral regurgitation but had not had any respiratory or systemic symptoms for two years. Chest radiographs and CT scans showed slowly increasing consolidation with internal areas of low attenuation, and without cavity formation, at the left S8. The erythrocyte sedimentation rate, C-reactive protein level, WBC count, percentage of eosinophils, and IgE level were 35 mm/hr, negative, 8400, 17%, and 3628 IU/ml, respectively. Eosinophils were found in samples of sputum. His immunological status was normal. Transbronchial lung biopsy yielded necrotic tissue, along with gram-positive and irregular acid-fast branching filaments that grew in culture. The microorganism was identified as Nocardia asteroides. Occupational inhalation of soil may have caused his disease.

Aged↗
PubMed1995

Pharmacological evidence for the persistent activation of ATP-sensitive K+ channels in early phase of reperfusion and its protective role against myocardial stunning.

BACKGROUND: The activation of cardiac ATP-sensitive potassium channels is reported to protect myocardium during ischemia. However, the behavior and role of this channel during reperfusion remain uncertain. METHODS AND RESULTS: Guinea pig right ventricular walls were studied by use of microelectrodes and a force transducer. Each preparation was perfused via the coronary artery at a constant flow rate and was stimulated at 3 Hz. In the first protocol, the preparation was subjected to 10 minutes of no-flow ischemia, which was followed by 60 minutes of reperfusion. Introduction of ischemia shortened the action potential duration (APD) to 58.7 +/- 3.1% of the preischemic values, in association with a decrease in the resting membrane potential (by 12 +/- 0.8 mV) and action potential amplitude (by 34.6 +/- 1.8 mV). On reperfusion, although the APD was restored, it remained shortened for up to approximately 30 minutes of reperfusion. In the presence of glibenclamide (10 mumol/L), the shortening of the APD during ischemia was significantly attenuated and the restoration of APD after reperfusion was significantly facilitated. When glibenclamide was applied from the onset of reperfusion, the persistent APD shortening was significantly suppressed. The developed tension decreased during ischemia and recovered after 60 minutes of reperfusion (up to 92.0 +/- 6.4% of preischemic values) in the untreated preparations. The application of glibenclamide that was started before ischemia or from the onset of reperfusion significantly suppressed the recovery of contractility (P < .05 versus untreated preparations). In the second series of experiments, 20 minutes of no-flow ischemia and 60 minutes of reperfusion were applied. This protocol produced a sustained contractile dysfunction after reperfusion (to 34.0 +/- 3.2% of preischemic values). In the presence of cromakalim (2 mumol/L), the APD shortening was enhanced during both ischemia and the early reperfusion period. Cromakalim significantly improved the contractile recovery (to 79.3 +/- 4.1% of preischemic values, P < .05 versus untreated preparations). The application of cromakalim that was started from the onset of reperfusion also improved the contractile recovery during this phase and this effect was associated with enhanced APD shortening. However, the cromakalim-treated preparations demonstrated a higher incidence of ventricular fibrillation during reperfusion. CONCLUSIONS: Cardiac ATP-sensitive potassium channels are activated by ischemia, and a fraction of these channels remains activated during the early reperfusion phase. The resulting shortening of the APD prevents the heart from developing myocardial stunning.

Action Potentials↗
PubMed1995

Induction of TCR-gamma delta+ cells from thymocytes stimulated by a fetal liver-derived hepatocyte clone.

We have previously reported that a fetal liver-derived hepatocyte clone, FHC-4D2, can support hematopoiesis in vitro. Here, we show that fetal thymocytes (FT) or adult thymocytes (AT) proliferate on the monolayer of FHC-4D2 cells in the presence of rIL-2. Fresh thymocytes contained few TCR-gamma delta+ cells (< 4% for FT and < 1% for AT); significant numbers of TCR-gamma delta+ cells were detected (2-11% for FT and 15-33% for AT) after the coculture with FHC-4D2 and rIL-2. Although FT-derived TCR-gamma delta+ cells predominantly used the V gamma 5 chain, the major population in AT-derived TCR-gamma delta+ cells used V gamma 1, V gamma 4, or V gamma 7 chains. Both FT- and AT-derived TCR-gamma delta+ cells killed FcR-bearing target cells when incubated with anti-TCR-gamma delta Ab. Half of FT-derived TCR-gamma delta+ cells were CD4-CD8 alpha+8 beta-; the rest were CD4-CD8 alpha-8 beta-. AT-derived TCR-gamma delta+ cells expressed neither CD4 nor CD8 molecules. Separation of thymocytes from FHC-4D2 cells with a membrane filter reduced the proliferative response by two- to threefold. Taken together, these results demonstrate that a fetal hepatocyte clone supports thymocytes to develop preferentially into TCR-gamma delta+ cells in cooperation with rIL-2 through cell-cell contact, that the repertoire and the phenotype of induced TCR-gamma delta+ cells are determined by the age of the mice, and that hepatocytes might thus play an active role in T lymphopoiesis in the fetal liver.

Age Factors↗
PubMed1995

alpha-amylase inhibitor increases plasma 3-hydroxybutyric acid in food-restricted rats.

The effect on energy metabolism of delayed absorption of starch by inhibition of alpha-amylase was examined by considering levels of plasma glucose and 3-hydroxybutyric acid (3-OHBA) in rats. Addition of alpha-amylase inhibitor (alpha AI) to a high starch diet delayed the plasma glucose response after feeding: peak plasma glucose levels in the control group occurred 15 min after feeding, whereas in the alpha AI group this peak did not occur until 30 min after. The total plasma glucose response was not different between the two groups. Plasma 3-OHBA levels 1 day after food restriction increased approximately five-fold in both groups. After 3 days of food restriction, the alpha AI group maintained the same level of plasma 3-OHBA as after 1 day of food restriction, while the control group showed significantly decreased levels of 3-OHBA. After 3 days of food restriction, plasma insulin levels were significantly decreased in the alpha AI group compared with the corresponding levels of the control group and with levels before the restriction. There was no significant difference in body weight between the two groups. These findings suggest that delayed hyperglycemia due to delayed absorption of starch following alpha AI loading may attenuate insulin secretion, leading to altered metabolism of 3-OHBA during the delayed response to energy deficit.

3-Hydroxybutyric Acid↗
PubMed1995

Silent cortical strokes associated with atrial fibrillation.

To clarify whether silent cortical strokes (SCS) could be a predictor of symptomatic stroke in patients with atrial fibrillation (AF), 72 patients with AF (50 with chronic AF, 22 with paroxysmal AF) were studied. Patients with mitral stenosis, history of myocardial infarction, or dilated cardiomyopathy were excluded from this study. Using cranial magnetic resonance imaging (MRI), the patients were divided into those with SCS (23 patients, Group 1) and those without SCS (49 patients, Group 2). The incidence of symptomatic stroke was then compared between the two groups. Three patients (13%) in Group 1 developed symptomatic brain infarction; this is statistically significant (p < 0.05), compared with the patients in Group 2, none of whom experienced symptomatic stroke. We suggest that SCS is a predictor of symptomatic cerebral infarct in patients with AF. Therefore, it is thought to be important to diagnose SCS using cranial MRI or computed tomography and to keep patients with SCS under close surveillance.

Aged↗
PubMed1995

Histamine receptor and its regulation of energy metabolism.

In a series of studies on brain functions of histamine, probes to manipulate activities of histaminergic neuronal systems were applied to assess histaminergic function in non-obese normal, and lean and obese Zucker rats. Food intake was suppressed by both activation of H1-receptors and inhibition of H3-receptors in the ventromedial hypothalamic nucleus (VMH) and the paraventricular nucleus, each of which is a satiety center. Feeding circadian rhythm was decreased in its amplitude through histaminergic modulation in the hypothalamus. Histamine neurons in the mesencephalic trigeminal nucleus (Me5) were involved in regulation of masticatory functions, particularly eating speed, while histamine-containing neurons in the VMH controlled intake volume of meals. Energy deficiency in the brain enhanced satiation through histaminergic activation of VMH neurons, which in turn produced glycogenolysis in the hypothalamus to maintain homoestatic control of glucose supply. A very-low-calorie conventional Japanese diet, which is a fiber rich and low energy food source, enhanced satiation by increased mastication and because of the low energy supply of the diet. Hypothalamic histamine neurons were activated by high ambient temperature and also by interleukin-1 beta, an endogenous pyrogen, to maintain homeostatic thermoregulation. Behavioral and metabolic abnormalities of Zucker obese rats were mediated by a deficit in hypothalamic neuronal histamine, and the Zucker rat was evaluated as an animal model of histamine deficiency. Transplantation of the lean fetal hypothalamus into the third cerebroventricle of host obese Zuckers attenuated the abnormalities.

Animals↗
PubMed1995

A very-low-calorie conventional Japanese diet: its implications for prevention of obesity.

A very-low-calorie conventional Japanese diet of 370 kcal/day has been shown to be useful for weight reduction and its long-term maintenance. Sources of the diet were mainly from chicken fillet, egg white, fish white-meat, mushroom, seaweed and low- or non-calorie fiber-rich vegetable, and contained 4.4g fat, 38.1g protein, 45.2g carbohydrate and essential minerals and vitamins. However, metabolic and neural implications of a commercial very-low-calorie liquid formula diet have rarely been investigated from the view point of food intake and appetite regulation. Animal studies have demonstrated the rationale for efficacy of the very-low calorie conventional Japanese diet as follows: (1) Increased hypothalamic histamine suppressed food intake through H1-receptors in the ventromedial hypothalamus (VMH) and paraventricular nucleus, the satiety centers. (2) Low energy intake enhanced satiety and decreased food intake through histaminergic activation of VMH neurons. (3) Mastication activated afferent signal transmission from proprioceptors in the oral cavity to the mesencephalic trigeminal nucleus(Me5). Histaminergic systems in the hypothalamus were activated by mastication and low energy supply, which was accompanied by satiation through the action of histamine in the VMH. Usefulness of the very-low-calorie conventional Japanese diet derives from utilization of conventional Japanese food stuffs as a fiber rich, low energy food source, and from enhancement of satiation by increased mastication required of the diet. The properties of the diet seemed to effect a closed positive feedback loop between histaminergic activation in hypothalamic satiety centers and behavioral changes to enhance satiation and cause feeding suppression.

Diet, Reducing↗
PubMed1995

Effects of auricular acupuncture stimulation on nonobese, healthy volunteer subjects.

Effects of auricular acupuncture stimulation on nonobese healthy volunteers were investigated. Subjects (n = 35) averaged 34.5 years old, and BMI was 25.3 kg/m2. Small (0.15 x 2.0 mm) auricular needles were applied intracutaneously into the bilateral cavum conchae that was identified by having less than 100 k omega resistance. Body weight was measured four times a day and charted by the subjects themselves. Results showed that, in the period 11-2, in which only body weight was measured, without auricular acupuncture stimulations, 57.1% of the subjects reduced their body weight. This indicates that charting body weight themselves might be useful to maintain their weight. In the auricular acupuncture treated period, 19 (70.4%) out of 27 decreased (p < 0.01), 5 (18.5%) was increased, and 3 (11.1%) had no change in body weight. In conclusion, the results suggest that success in maintaining weight reduction can be attributed to graphic illustration of one's weight pattern. Bilateral auricular acupuncture stimulation can also reduce body weight of healthy non-obese subjects. This is consistent with the suggestion that it might be effective in the treatment of obese patients.

Acupuncture Points↗
PubMed1995

Apolipoprotein A-IV: a circulating satiety signal produced by the small intestine.

How fat feeding, especially lipoproteins and apolipoproteins, may affect food intake is unclear. Apolipoprotein A-IV (apo A-IV) is a protein associated with chylomicrons, and its synthesis by the small intestine is markedly stimulated following ingestion of fat. We explored the anorectic effect of chylous lymph on feeding behavior. Intestinal lymph samples collected during lipid infusion intraduodenally when administered intravenously markedly suppressed food intake in fasting rats. To determine if the suppressor was lipid or apo A-IV, fasting rats were infused intravenously with a 2% Intralipid emulsion, but it did not suppress food intake. These data suggest that the factor in chylous lymph that suppresses food intake is probably apo A-IV. To test this, apo A-IV in chylous lymph was removed by immunoprecipitation, and the chylous lymph with apo A-IV removed lost its anorectic effect. Next, we infused purified apo A-IV intravenously in fasted rat, and it inhibited food intake in a dose-dependent manner. We therefore conclude that increased apo A-IV in chylous lymph is a factor involved in anorexia after fat feeding. Infusion of 0.5 microgram of apo A-IV into the third ventricle failed to suppress food intake. Higher doses (1 microgram or higher) of apo A-IV infused into the third ventricle inhibited food intake in a dose-dependent manner. To further test the hypothesis that apo A-IV is an important factor controlling food intake, we administered goat anti-rat apo A-IV serum into the third ventricle of rats that were allowed food and water ad libitum. In all rats tested, this treatment resulted in enhanced food intake. In conclusion, we propose that apo A-IV may act centrally to control food intake.

Animals↗
PubMed1995

Hypothalamic neuronal histamine modulates adaptive behavior and thermogenesis in response to endogenous pyrogen.

Homeostatic involvement of hypothalamic neuronal histamine in adaptive behavior and thermogenesis was investigated when interleukin-1 beta (IL-1 beta), one of the endogenous pyrogens, was infused peripherally in rats. IL-1 beta decreased food and water intake and elevated body temperature. Depletion of neuronal histamine in the hypothalamus induced by alpha-fluoromethylhistidine, a suicide inhibitor of the histamine synthesizing enzyme histidine decarboxylase (HDC), attenuated the suppressive effect of IL-1 beta on food intake, facilitated the inhibitory effect on water intake, and enhanced its thermogenic effect. Simultaneously IL-1 beta increased activity of HDC and histamine-N-methyltransferase (HMT), a neuronal histamine catabolizing enzyme. Pretreatment with indomethacin completely blocked those increases in turnover of neuronal histamine induced by IL-1 beta. Hypothalamic prostaglandin E2 (PGE2) activated by peripheral IL-1 beta, but not peripheral PGE2, increased both activities of HDC and HMT. Ginsenoside Rg1, a major component of panax ginseng, modulated the suppressive effects of IL-1 beta on ingestive behavior, resulting in a lowering of body temperature. The findings suggest that the effects of IL-1 beta on ingestive behavior and thermogenesis may be modulated by dynamics of hypothalamic neuronal histamine through activation of hypothalamic PGE2 which is elevated by peripheral IL-1 beta.

Adaptation, Physiological↗
PubMed1995

Histaminergic control of mucosal repair in the small intestine.

The aim of the present paper was to summarize histamine-mediated repair of rat intestinal mucosa. To evaluate intestinal repair, we examined lipid transport (an index of intestinal mucosal function) after 15 minutes occlusion of the superior mesenteric artery. Rats were pretreated with alpha-fluoromethylhistidine (a suicide inhibitor of histidine decarboxylase, a synthesizing enzyme of histamine), H1-receptor antagonist (chlorpheniramine maleate), H2-antagonist (cimetidine), or H3-antagonist (thioperamide) before ischemia-reperfusion (I/R). Lipid transport to rat mesenteric lymph decreased significantly 24 hours after I/R in all groups tested compared to sham-treated rats. Lipid transport was restored 48 hours after I/R in the vehicle-pretreated control group. Lipid transport was not restored to the control level 48 hours after I/R in rats pretreated with H1-antagonist and a suicide inhibitor of histidine decarboxylase. In contrast, intestinal function was restored to the control level 48 hours after I/R in rats pretreated with H2- and H3-antagonists. These results support our previous findings that newly formed histamine after I/R plays an important role in mucosal recovery through H1-receptors.

Animals↗
PubMed1995

Surgical treatment of renal cell carcinoma metastases: prognostic significance.

Between January 1980 and March 1993, 166 patients with renal cell carcinoma were treated at Nagoya University Hospital. Among them 16 (9.6%) underwent surgical removal of 21 metastatic lesions: 12 patients had distant metastases at diagnosis and the other 4 demonstrated new distant metastases during their clinical course after nephrectomy. The metastatic lesions involved the brain in 6 patients, bone in 4, lung in 2, contralateral adrenal glands in 2, soft tissues in 2, lymph nodes in 2, pleura in 1, pancreas in 1, and contralateral renal pelvis in 1. All of the 16 patients underwent nephrectomy and 15 of them (93%) received interferon-alpha therapy. Patients with lesions which were completely resected had significantly longer survival than those with lesions which were palliatively treated and those with metastatic lesions at other sites (p = 0.02). Improvement of performance status was observed in 5 of 6 (83%) patients undergoing palliative surgical treatment. The present study suggests that surgical removal of metastatic lesions prolongs survival in a limited number of renal cell carcinoma patients and that it improves performance status in those symptoms related to metastasis.

Bone Neoplasms↗
PubMed1995

Gender differences of disturbed hemostasis related to fasting insulin level in healthy very elderly Japanese aged > or = 75 years.

We investigated the relationship between fasting insulin level and various hemostatic factors, including fibrinolytic factors (active plasminogen activator inhibitor-1 (PAI-1), tissue type plasminogen activator (tPA)-PAI-1 complex, plasmin-alpha 2-plasmin inhibitor (PIC), and D-dimer), coagulation factors (activated factor VII, factor VII coagulant activity and antigen, factor VIII, factor X, and fibrinogen), coagulation inhibitors (antithrombin III, heparin cofactor II, and protein C), and an acute phase marker (sialic acid) in 102 healthy individuals aged > or = 75 years (46 men and 56 women). Active PAI-1 levels had a significant negative correlation with PIC levels (r = -0.342, P = 0.0006), indicating that PAI-1 influences in vivo fibrinolytic activity in the very elderly. Gender differences were found in the relationship between insulin and hemostatic abnormalities, with the insulin level being positively correlated with coagulation factors in men (factor VIII activity: r = 0.422, P < 0.01; factor VII activity: r = 0.386, P < 0.01) and with hypofibrinolysis in women (active PAI-1: r = 0.549, P < 0.0001). Insulin levels were positively correlated with the levels of factor VII antigen and factor VII activity in men (P < 0.01), but there was no correlation with activated factor VII levels. The fasting insulin level was also correlated with the levels of heparin cofactor II and sialic acid in men (P < 0.05). However, other hemostatic factors were not related to the insulin level in either sex.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Ginsenoside Rg1 modulates ingestive behavior and thermal response induced by interleukin-1 beta in rats.

Effects of ginsenoside Rg1 (Rg1), a major component of panax ginseng, on changes in ingestive behavior and rectal temperature induced by interleukin-1 beta (IL-1 beta) were investigated in rats. Intraperitoneal (ip) injection of IL-1 beta suppressed food and water intake and elevated rectal temperature. The suppressive effect of IL-1 beta on water intake was converted to an increase when 4.0 mM Rg1 was continuously infused into the third cerebroventricle (ICV) at a rate of 0.966 microliters/h. The elevation of rectal temperature induced by IL-1 beta was attenuated by ICV infusion of Rg1. The feeding suppression caused by IL-1 beta was unaffected by ICV infusion of Rg1. These results suggest that sustained ICV infusion of Rg1 may modulate the effects of IL-1 beta on ingestive behaviors, i.e., increase in water intake and sustained decrease in food intake, resulting in a lowering of body temperature.

Animals↗