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Y Sakai

Publications and source records attributed to Y Sakai.

At least 415 records · Page 23Linked to original sources
PubMed1996

Regional differences in the pineal gland of the cotton rat, Sigmodon hispidus: light microscopic, electron microscopic, and immunohistochemical observations.

Light microscopic, electron microscopic and immunohistochemical observations of the various portions of the pineal gland of the cotton rat (Sigmodon hispidus) were made. The volume of the proximal half occupied about 30% of the whole organ, and pinealocytes were slightly smaller in size in the proximal portion than elsewhere. The distal and intermediate portions contained few interstitial cells and numerous astrocytes, but the proximal portion lacked interstitial cells and had more abundant astrocytes than elsewhere. Astrocytes, which were immunoreactive for glial fibrillary acidic protein, mainly lined the pericapillary spaces in the distal and intermediate portions, but in the proximal portion these cells often surrounded isolated or groups of pinealocytes. In the distal and intermediate portions, abundant sympathetic fibers and less numerous non-sympathetic, peptidergic fibers were mainly localized in the pericapillary spaces; these fibers were sparsely distributed in the parenchyma close to interstitial cells or astrocytes. In the proximal portion, non-sympathetic fibers were scarce and sympathetic fibers were distributed abundantly and almost exclusively in the parenchyma. Most of the sympathetic fibers were adjacent to astrocytes and, occasionally, made specialized contact with them. Fenestrae in the capillary endothelium were numerous in the distal portion but absent in the proximal portion. Thus, marked differences in structure existed between the distal and proximal portions of the pineal gland of the cotton rat suggesting that both portions are functionally dissimilar. In addition, the present study indicates that the proximal portion of the cotton rat was well developed and showed morphological features similar to the deeply situated pineal glands of other mammals.

Animals↗
PubMed1996

Comparative study of a mutant tissue-type plasminogen activator, YM866, with a tissue-type plasminogen activator in a canine model of femoral arterial thrombosis.

Because tissue-type plasminogen activator (tPA), used to treat myocardial infarction, has several disadvantages thought to be connected with its low half-life, mutants of tPA have been prepared with longer half-lives. We have compared the thrombolytic effect of such a mutant, YM866, with that of tPA in copper-coil-induced femoral arterial thrombosis in dogs. One hour after thrombus formation, YM866 was administered by intravenous bolus injection, while tPA was given by the same method or by 60-min infusion under adequate heparinization. Both agents exhibited dose-dependent thrombolysis without systemic fibrinogenolysis. The recanalization rate and recanalization time of YM866 by bolus at 0.2 mg kg-1 were, however, equivalent to those of tPA by infusion at 0.4 mg kg-1 (total dose), whereas the recanalization rate of tPA by bolus was low (0.4 mg kg-1). No significant difference in reocclusion rate, reocclusion time, or patency status after successful thrombolysis was seen. These results suggest that YM866 administered at a lower dose by intravenous bolus injection exerted a thrombolytic effect equivalent to that of tPA by infusion, and that heparin could not prevent reocclusion after successful thrombolysis even under adequate anticoagulation.

Animals↗
PubMed1996

Bioconversion of 7-Aminocephalosporanic Acid by Intact Rhodotorula glutinis Cells.

When 7-aminocephalosporanic acid (7-ACA) was used as a single carbon source in the enrichment culture medium for screening 7-ACA-degrading microorganisms, pink yeast colonies appeared frequently, and these were identified as Rhodotorula glutinis. These intact R. glutinis cells converted (i) 7-ACA to deacetyl-7-ACA (7-ADACA) and (ii) monochloroacetyl-7-ACA to monochloroacetyl-7-ADACA at sufficiently high levels to be of commercial interest. Acetylation of 7-ADACA to 7-ACA, the reverse reaction of hydrolysis in an organic medium with methyl acetate as an acetyl donor, was also demonstrated.

Journal Article↗
PubMed1996

Isolation and characterization of a novel oxygenase that catalyzes the first step of n-alkane oxidation in Acinetobacter sp. strain M-1.

In the Finnerty pathway for n-alkane, oxidation in Acinetobacter sp., n-alkanes are postulated to be attacked by a dioxygenase and the product, n-alkyl hydroperoxide, is further metabolized to the corresponding aldehyde via the peroxy acid [W. R. Finnerty, P. 184-188, in A. H. Applewhite (ed.), Proceedings of the World Conference on Biotechnology for the Fats and Oil Industry, 1988]. However, no biochemical evidence regarding the first-step reaction is available. In this study, we found a novel n-alkane-oxidizing enzyme that requires only molecular oxygen, i.e., not NAD(P)H, in our isolate, Acinetobacter sp. strain M-1, and purified it to apparent homogeneity by gel electrophoresis. The purified enzyme is a homodimeric protein with a molecular mass of 134 kDa, contains 1 mol of flavin adenine dinucleotide per mol of subunit, and requires CU2+ for its activity. The enzyme uses n-alkanes ranging in length from 10 to 30 carbon atoms and is also active toward n-alkenes (C12 to C20) and some aromatic compounds with substituted alkyl groups but not toward a branched alkane, alcohol, or aldehyde. Transient accumulation of n-alkyl hydroperoxide was detected in the course of the reaction, and no oxygen radical scavengers affected the enzyme activity. From these properties, the enzyme is most probably a dioxygenase that catalyzes the introduction of two atoms of oxygen to the substrate, leading to the formation of the corresponding n-alkyl hydroperoxide. The enzymatic evidence strongly supports the existence of an n-alkane oxidation pathway, which is initiated by a dioxygenase reaction, in Acinetobacter spp.

Acinetobacter↗
PubMed1996

Serum tumor necrosis factor in mesangial IgA glomerulonephritis with macroscopic hematuria in children.

Tumor necrosis factor (TNF)-alpha and interferon (INF)-gamma levels were measured in the sera obtained from 29 patients with IgA glomerulonephritis (IgA GN), 8 patients with minimal change nephrotic syndrome (MCNS) and 12 patients with upper respiratory tract infection (URI) without renal diseases in children. The serum TNF-alpha level of IgA GN was 123.0 +/- 175.4 pg/ml, MCNS was 4.9 +/- 4.0 pg/ml and URI was 10.5 +/- 4.5 pg/ml respectively. The serum TNF-alpha level of IgA GN was significantly higher than those of MCNS and URI. The serum TNF-alpha level of URI was on the high trend compared with that of MCNS, but was not statistically significant. Although the TNF-alpha level was related to mesangial cell proliferation in patients with IgA GN, it was unrelated to the grade of mesangial matrix expansion and magnitude of proteinuria. In 17 patients with IgA GN having macroscopic hematuria, the serum TNF-alpha level was 190.5 +/- 201.6 pg/ml, and in other IgA GN patients with microscopic hematuria it was 37.4 +/- 75.7 pg/ml. The serum TNF-alpha level of IgA GN with macroscopic hematuria was significantly higher than that with microscopic hematuria. In 6 patients with IgA GN with macroscopic hematuria, the serum TNF-alpha level was significantly decreased after macroscopic hematuria disappeared. The mean serum IFN-gamma level of IgA GN was 0.3 +/- 0.6 IU/ml, and MCNS was not detectable. Although the serum IFN-gamma level was related to mesangial cell proliferation in patients with IgA GN, it was unrelated to magnitude of proteinuria, the grade of mesangial matrix expansion and also the presence or absence of macroscopic hematuria. We suggest that macroscopic hematuria of IgA GN was closely related to the serum TNF-alpha level.

Adolescent↗
PubMed1996

Characteristics of anti-HCV antibody-positive patients with hepatocellular carcinoma on chronic hemodialysis: recommendation of periodic ultrasonography for early detection.

We analyzed 10 patients (male:female 9:1, mean age 64.2 years) who developed hepatocellular carcinoma during the observation period of 2 years among 2,164 chronic hemodialysis patients in 23 dialysis centers. Among them, 409 patients were positive for serum anti-HCV antibodies (19%). They were all positive for serum anti-HCV antibodies but negative for HBs antigen. None of the anti-HCV antibody-negative patients developed hepatocellular carcinoma during this period. Although liver function tests of the patients were almost normal, pathological examination of the liver revealed chronic active hepatitis or cirrhosis. Periodic ultrasonographic examination is necessary for early detection of hepatocellular carcinoma in chronic hemodialysis patients with positive anti-HCV antibodies even if liver function tests are within normal ranges.

Aged↗
PubMed1996

Regulation of corticotropin-releasing factor receptor messenger ribonucleic acid in rat anterior pituitary.

Adrenalectomy (ADX) leads to a decrease in the number of CRF-binding sites in the rat anterior pituitary (AP). However, the molecular mechanisms of CRF receptor (CRF-R) regulation are unknown. In the present study, we analyzed the effects of ADX on pituitary CRF-R1 messenger RNA (mRNA) levels in vivo and the direct effects of CRF, arginine vasopressin (AVP), and glucocorticoid, the levels of which are altered by ADX, on CRF-R1 mRNA levels in vitro. The mRNA level was determined by Northern blot analysis using a rat brain CRF-R1 complementary RNA probe. The CRF-R1 level in AP fell to 20% of the sham level 1 day after ADX and returned to the sham level after 14 days. In cultured rat AP cells, treatment with CRF, AVP, and dexamethasone led to significant reductions in CRF-R1 mRNA, with maximal inhibition to 32%, 22%, and 37% of control levels, respectively. The time course of CRF-R1 mRNA reduction varied depending on the drug, with effects detectable as early as 1 h after treatment. These findings indicate that elevated portal CRF and AVP levels may contribute to the decrease in CRF-R1 mRNA soon after ADX. A decrease in mRNA levels, in turn, may lead to a decrease in CRF-R1 protein on corticotrophs.

Adrenalectomy↗
PubMed1996

Major role of 3',5'-cyclic adenosine monophosphate-dependent protein kinase A pathway in corticotropin-releasing factor gene expression in the rat hypothalamus in vivo.

To assess whether the cAMP-dependent protein kinase-A and/or the diacylglycerol-dependent protein kinase C (PKC) pathways play important roles in the activation of CRF neurons in vivo under physiological conditions, we tested the effect of microinjection of 8-bromo-cAMP (8-Br-cAMP) or 12-O-tetradecanoyl phorbol 13-acetate (TPA) into both paraventricular nuclei (PVN) of the hypothalamus in conscious rats. Both 8-Br-cAMP and TPA increased plasma ACTH concentrations and the POMC messenger RNA (mRNA) concentrations in the anterior pituitary. While injection of 8-Br-cAMP also increased CRF mRNA concentrations in hypothalamic tissue containing the PVN, TPA injection had no effect on CRF mRNA concentrations there. During insulin-induced hypoglycemia, which stimulates CRF gene expression and release, c-fos and c-jun mRNA increases in the hypothalamic tissue preceded the increase in the CRF mRNA level after insulin-induced hypoglycemia. Antisense oligodeoxyribonucleotides (oligos) directed against c-fos, c-jun, or the cAMP response element binding protein (CREB) mRNA were injected into both PVN before insulin-induced hypoglycemia to assess whether activator protein-1 or CREB mediates transcriptional activation of CRF during hypoglycemia. Only antisense oligo against CREB mRNA reduced the CRF mRNA level after insulin-induced hypoglycemia. These results suggest that protein kinase A may transduce intracellular signals in CRF neurons under physiological conditions and raises the possibility that CREB may be involved in stress-induced CRF gene expression.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Triterpene saponins from Abrus cantoniensis (Leguminosae). II. Characterization of six new saponins having a branched-chain sugar.

The chemical structures of abrisaponins So1 (1), So2 (2), D2 (3), D3 (4), F (5) and SB (6), six of twenty-three saponins from Abri Herba, the whole plants of Abrus cantoniensis (Leguminosae), were investigated. They were elucidated to be 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-[O-beta-D-glucopyranosyl-(1-->3)]-beta-D-galactopyranosyl-(1 --> 2)-beta-D-glucuronopyranosyl [sequence: see text] (designated as beta-abritetraosyl) sophoradiol (1), 3-O-beta-abritetraosyl sophoradiol 22-O-beta-D-xylopyranoside (2), 3-O-beta-abritetraosyl abrisapogenol D (3), O-beta-abritetraosyl abrisapogenol D 22-O-beta-D-glucopyranoside (4), 3-O-beta-abritetraosyl abrisapogenol F (5) and 3-O-beta-abritetraosyl soyasapogenol B (6), respectively.

Fabaceae↗
PubMed1996

Production of fructosyl lysine oxidase from Fusarium oxysporum S-1F4 on autoclave-browned medium.

In Fusarium oxysporum S-1F4, fructosyl lysine oxidase (FLOD) was induced with N epsilon-fructosyl N alpha-Z-lysine (epsilon-FL), which is a model compound of a glycated protein, and the induction was inhibited by the addition of cycloheximide in the growing cells. FLOD formation was greatly enhanced in an autoclave-browned medium containing glucose and L-lysine. Some Amadori compounds formed from glucose and L-lysine during autoclaving were assumed to induce the enzyme. After optimization of the culture conditions, FLOD produced in the browned medium was comparable to that in the medium with epsilon-FL.

Amino Acids↗
PubMed1996

Serum dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEA-S) in Alzheimer's disease and in cerebrovascular dementia.

A decreased concentration of dehydroepiandrosterone sulfate (DHEA-S) in patients with Alzheimer's disease (AD) has been reported but is still controversial. In the present study, serum concentrations of DHEA and DHEA-S were determined in 19 patients with AD, 21 patients with cerebrovascular dementia (CVD) and 45 age- and gender matched elderly control individuals from the Japanese community at large. Serum concentration of DHEA among controls, patients with AD and patients with CVD did not significantly differ from one another. However, patients with AD and patients with CVD were found to have lower concentration of serum DHEA-S and a lower DHEA-S/DHEA ration compared to normal control individuals. No significant difference was observed in the concentration of serum DHEA-S or the DHEA-S/DHEA ratio between patients with AD and those with CVD. These results suggest that reduced concentrations of serum DHEA-S may not be unique to AD, but instead reflect a common phenomenon in dementing diseases. However, since serum concentration of DHEA in these patients remained unchanged, the significance of DHEA in dementia remains unclear.

Aged↗
PubMed1996

Expression of sterol carrier protein 2 (SCP2) in human adrenocortical tissue.

Sterol carrier protein 2 (SCP2) has been implicated in adrenal steroidogenesis by in vitro studies. In order to clarify the clinical significance of SCP2 in human steroidogenesis, we investigated the expression of SCP2 mRNA in various types of adrenocortical tissue and one testis and examined the correlation between the amounts of SCP2 and other values such as the free cholesterol content and the cholesterol side-chain cleavage (SCC) activity in the tissue mitochondria. The types of adrenocortical tissue examined included adrenocortical carcinomas (N = 3), adrenocortical adenomas from patients with Conn's syndrome (N = 3) and from patients with Cushing's syndrome (N = 3), non-functioning adrenocortical adenomas (N = 2) and normal adrenal glands (N = 2). Northern blot hybridization predominantly revealed a 1.8-kb SCP2 mRNA in all tissue specimens examined. The mRNA concentrations of SCP2 in two out of three adrenocortical carcinomas were relatively lower than those in other types of tissue. No other special tendency was observed regarding the mRNA expression levels in various tissue specimens. The mRNA concentrations of SCP2 correlated significantly with mitochondrial contents of free cholesterol (r = 0.67, p < 0.01), but was not correlated with the SCC activities in mitochondria measured by an in vitro enzyme assay. The mitochondrial SCC activities, however, were correlated significantly with the protein levels of mitochondrial P-450 scc determined by a Western blot analysis (r = 0.79, p < 0.01). The significant positive correlation between mRNA concentrations of SCP2 and the mitochondrial content of free cholesterol suggests that the central role of SCP2 in human steroidogenic tissues may be in part a translocation of cytoplasmic free cholesterol to the mitochondria, as demonstrated previously by in vitro studies.

Actins↗
PubMed1996

Alteration of contractile properties to serotonin in gastric fundus smooth muscle isolated from streptozotocin (STZ)-induced diabetic rats.

Contractile responses to serotonin (5-HT) of fundic smooth muscle strips isolated from both control and streptozotocin (STZ)-induced diabetic rats were investigated. Contrary to carbachol (CCh) which causes contractile hyperactivity in DM, 5-HT response tended to decrease in DM compared to that of the control. Pindolol (10(-5)M) increased the value of EC50 of the concentration-response to 5-HT about 2.5 times in both the control and DM. After treatment with pindolol, the maximal tension to 5-HT in DM significantly decreased compared to that of the control. Pindolol showed no effect on the contractile response to CCh. Pindolol significantly inhibited the relaxation caused by isoproterenol in DM more than in the control. Mianserin (10(-5) M) increased the EC50 of the response to 5-HT about 2-2.5 times in both groups, but did not cause a significant difference between the control and DM. The Ca(2+)-induced contraction caused hyperreactivity in DM in the presence of 10(-6) M CCh, but that in DM was not significantly different from the control in the presence of 10(-6) M 5-HT. Pretreatment of phorbol 12-myristate 13-acetate (PMA, 10(-5) M) significantly attenuated the response to 5-HT in the control, but not in DM. Results suggest that the contractile response to 5-HT in DM is related to the altered Ca2+ signal transduction system via disturbed protein kinase C (PKC) activity, and that there are alterations of receptor characteristics and of the density in 5-HT receptor subtypes, especially 5-HT1A, during DM development.

Animals↗
PubMed1996

Cyclic Cushing's disease in long-term remission with a daily low dose of bromocriptine.

A 56-year-old male patient with cyclic Cushing's disease remained in a state of remission for more than one year with a relatively low dose of bromocriptine (2.5-3.75 mg/day). It has been reported that bromocriptine treatment for cyclic Cushing's disease induces only a transient remission; in the most effective cases, a relatively high dose (40 mg/day) was necessary. In the hypercortisolemic state, plasma adrenocorticotropic hormone (ACTH) and serum cortisol were not suppressed by dexamethasone and did not respond to corticotropin-releasing factor (CRF). An antehypophysectomy was not effective, even though the resected tissue contained ACTH-positive microadenomas. The present observations thus indicate the effectiveness of bromocriptine for some patients with this rare disorder.

Adenoma↗
PubMed1996

[Sedation with flunitarazepam at magnetic resonance imaging in the elderly patients with dementia].

Magnetic resonance imaging (MRI) of the brain is useful in diagnosing senile dementia, but to avoid the creation of artifacts the patient should be kept immobile. We studied the effects of pretreatment with flunitrazepam, a sleep inducer of the benzodiazepine class, as a sedative prior to imaging. The subjects consisted of 108 patients with senile dementia admitted to the Dementia Ward of Kyoto Higashiyama Geriatric Hospital. Their ages ranged from 64-95 years (mean, 81) and the mean body weights of the 76 women and 32 men were 36 and 47 kg, respectively. Immediately before undergoing MRI the patients were given a slow intravenous injection of flunitrazepam (2 mg/ml diluted in 19 ml of saline). Immediately before the patients fell asleep, administration was discontinued and the dose was noted: mean 0.008 mg/kg. In all patients sleep induction and sedation were achieved. No adverse reactions such as apnea were observed. The flunitrazepam dose in our study was much lower than that in previous reports on adults. As body weights of the elderly are also lower than those of younger adults, the optimum dose of flunitrazepam for the elderly may be much lower. Intravenous flunitrazepam may be a useful and safe premedication for MRI in elderly patients with dementia. To avoid serious adverse reactions the dose should be minimized by: 1) determining body weight before MRI, 2) administering diluted flunitrazepam, and 3) discontinuing the drug before the patient falls asleep.

Aged↗
PubMed1996

Permanent occlusion of bilateral internal carotid arteries produces cognitive deficits in two learning behavior tasks.

We investigated the effects of permanent bilateral occlusion of the internal carotid arteries (2ICAO) on the learning and memory performances in rats to evaluate the permanent 2ICAO rats as a model for vascular dementia. The learning and memory performance was tested by a step-through passive avoidance task and an 8-arm radial maze task. Permanent 2ICAO decreased cerebral blood flows in the cortex and hippocampus by 46.3 +/- 3.3 and 21.1 +/- 4.6%, respectively, when measured at 15 min after occlusion. In the passive avoidance task, the 2ICAO rats showed no impairment of learning or of memory retention when tested 1 h after learning trial, while they showed a shorter latency than sham-operated rats when tested 24 h after learning trial. In the radial maze learning task, the non-pretrained 2ICAO rats showed impairment. The pretrained 2ICAO rats had no deficit in the radial maze retention task but they showed impaired performance when a 3-min delay was interposed in the task. These results suggest that permanent 2ICAO is a useful animal model for studying vascular dementia.

Animals↗
PubMed1996

[Influence of recirculation type blood cardioplegia on perfusion pressure in open heart surgery].

Infusion blood cardioplegia often decreases the perfusion pressure during open heart surgery. The blood level of bradykinin (BK) was measured in both the cardiopulmonary bypass (CPB) and blood cardioplegia circuit. Infusion cardioplegia with recirculation type circuit increased the BK level of cardioplegia and the perfusion pressure decreased abruptly with the increase BK level in the CPB circuit. In the case of single pass type circuit the BK level was not increased either in cardioplegia or CPB and perfusion pressure was not decreased. We concluded that the single pass type of cardioplegia circuit is superior to the recirculation type because of less production of BK.

Aged↗