Biomedical subjects

K Sakai

Publications and source records attributed to K Sakai.

At least 289 records · Page 16Linked to original sources

PubMed1999

Effect of different sensitizing doses of antigen in a murine model of atopic asthma.

The dose of antigen is assumed to be one of the important factors in the polarized development of helper T cell subsets, i.e. Th1 or Th2 cells. We investigated the effect of the sensitizing antigen dose in a murine model of atopic asthma, which involved sensitization with ovalbumin (OVA) followed by repeated exposure to OVA aerosols. BALB/c mice were primed with varying doses of OVA (0, 10, 100 and 1000 microg) plus Al(OH)3 on days 0, 7 and 14, and were challenged with OVA aerosols (50 mg/ml for 20 min) on days 15-20. There were striking antigen dose-related differences in OVA-specific antibodies: high IgE and low IgG2a titres were found in mice sensitized at 10 microg, while low IgE and high IgG2a titres were seen at 1000 microg. The sensitizing dose was inversely correlated with the total cell count and the eosinophil count in bronchoalveolar lavage fluid (BALF), as well as with the extent of histological changes such as goblet cell hyperplasia of the bronchial epithelium and cellular infiltration into bronchovascular bundles. Antigen-induced bronchial hyper-responsiveness (BHR) to methacholine was observed with sensitization at 10 microg but not at 1000 microg. Splenic mononuclear cells (SMNC) obtained from mice sensitized at either dose showed proliferation in response to OVA. Production of IL-4 and IL-5 by OVA-stimulated SMNC was inversely correlated with the dose of sensitizing antigen. High-dose sensitization resulted in general suppression of cytokine production by SMNC, including interferon-gamma (IFN-gamma). The BALF levels of IL-4 and IL-5 were increased by low-dose sensitization, whereas IFN-gamma and IL-12 levels were increased by high-dose sensitization. These results suggest that the dose of sensitizing antigen defines the phenotypic changes in the present murine asthma model, presumably by influencing the pattern of cytokine production.

Animals↗

PubMed1999

Differentiation between brewing and non-brewing yeasts using a combination of PCR and RFLP.

In order to differentiate brewing from non-brewing yeasts, a specific polymerase chain reaction (PCR) which targeted the open reading frame of FLO1 was employed. Non-brewing yeasts include 'non-brewing Saccharomyces yeasts' and 'non-Saccharomyces yeasts'. The molecular sizes of the PCR products differed between brewing and non-brewing Saccharomyces yeasts. No FLO1 PCR products were obtained from non-Saccharomyces yeasts. Specific PCR, using oligonucleotide primers that targeted the region between the 5S and 26S rRNA genes, could be used to differentiate brewing yeasts from some non-brewing yeasts. These PCR products were digested with restriction enzymes, Scr FI and Msp I. Different restriction profiles were obtained from brewing and non-brewing yeasts which could not be differentiated using specific PCR of rDNA. These results suggest that it is possible to identify brewing from non-brewing yeasts using specific PCR of FLO1 and rDNA, and detection of restriction fragment polymorphism of rDNA.

Beer↗

PubMed1999

Effects of microdialysis application of monoamines on the EEG and behavioural states in the cat mesopontine tegmentum.

The peri-locus coeruleus alpha (peri-LCalpha) of the mediodorsal pontine tegmentum contains cholinergic and non-cholinergic neurons, and is critically implicated in the regulation of both wakefulness and paradoxical sleep (PS). The peri-LCalpha receives dense monoaminergic (adrenergic, noradrenergic, serotonergic, dopaminergic and histaminergic) afferent projections, but little is known about their exact roles in the control of sleep-wake cycles. We have therefore examined the in vivo effects of microdialysis application of monoamines to the peri-LCalpha and adjacent cholinergic and non-cholinergic tegmental structures on behavioural states and the electroencephalogram (EEG) in freely moving cats. Norepinephrine, epinephrine and dopamine selectively inhibited PS and induced PS without atonia when applied to the caudal part of the peri-LCalpha, which mainly contains non-cholinergic descending neurons, whereas histamine and serotonin had no effect at this site. In the rostral part of the peri-LCalpha and the adjacent X area (nucleus tegmenti pedunculopontinus, pars compacta), which contain many ascending cholinergic neurons, norepinephrine and epinephrine suppressed PS with a significant increase in waking and a decrease in slow-wave sleep, as expressed by a marked decrease in the power of the cortical and hippocampal delta (0.5-2.5 Hz) and cortical alpha (8-14 Hz) bands, and an increase in the cortical gamma (30-60 Hz) band. At these sites, histamine had similar waking and EEG-desynchronizing effects, but never suppressed PS, while dopamine and serotonin had no effect. These findings indicate a special importance of the adrenergic, noradrenergic and dopaminergic systems in the inhibitory or permissive mechanisms of PS, and of the adrenergic, noradrenergic and histaminergic systems in the control of behavioural and EEG arousal.

Animals↗

PubMed1999

An MR image of spinal cord sarcoidosis.

We present a case of spinal cord sarcoidosis with a unique magnetic resonance imaging (MRI) finding. MRI of the cervical spine revealed an unusual lesion of low signal intensity on T2-weighted image at the core of the lesion surrounded by high signal intensity. T1-weighted gadolinium enhanced image showed a high signal at the core lesion. Low signal intensity on T2-weighted image in the case was suggested to be due to hemosiderin deposition. Steroid therapy dramatically improved clinical symptoms with a marked reduction of peripheral T2 high intensity area and the core lesion size detected by gadolinium enhancement.

Aged↗

PubMed1999

Age-related changes in alpha-tocopherol dynamics with relation to lipid hydroperoxide content and fluidity of rat erythrocyte membrane.

Age-related changes in alpha-tocopherol dynamics in plasma and erythrocyte membranes of 10- to 120-week-old rats were investigated by high-performance liquid chromatography (HPLC) with redox detection mode. Furthermore, changes in lipid hydroperoxide content and fluidity of erythrocyte membrane with age were assessed using chemiluminescence-HPLC and Fourier transform infrared spectrophotometer, respectively. A slight increase in the alpha-tocopherolquinone/alpha-tocopherol ratio in erythrocyte membrane and a decrease in the alpha-tocopherol in erythrocyte membrane/alpha-tocopherol in plasma ratio were observed. A significant increase in lipid hydroperoxide content and a marked decrease in the fluidity of erythrocyte membrane were seen with age. These findings suggest that alpha-tocopherol uptake in erythrocyte membrane declines, and utilization rate of alpha-tocopherol in erythrocyte membrane increases age-dependently. These changes, which enhanced lipid peroxidation and consequently reduced membrane fluidity, may be caused by the impairment of this transfer mechanism.

Aging↗

PubMed1999

Human parathyroid hormone (1-34) transiently increases the excretion of lysosomal enzymes into urine and the size of renal lysosomes.

It has been reported that the urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG), a lysosomal enzyme, transiently increases in human after treatment with human parathyroid hormone (hPTH)(1-34). We report here that hPTH(1-34) caused transient changes in the size and density of rat renal lysosomes following urinary excretion of NAG and other lysosomal enzymes tested. Percoll density gradient centrifugation revealed that hPTH(1-34) slightly but significantly increased the fraction of high density lysosomes (around 1.12 g/ml) 5-10 min after the treatment with hPTH(1-34), with a concomitant decrease in the fraction of intermediate density lysosomes (1.07-1.08 g/ml). On electron micrographs, some lysosomes in proximal tubules but not in distal tubules showed a change in morphology from circular to oval, and became enlarged and electron-dense 5-10 min after the treatment with hPTH(1-34). These responses to hPTH(1-34) were also reversible and transient. NAG excreted in urine after treatment with hPTH(1-34) had the molecular mass of a mature form in lysosomes and/or endosomes and was not a prepro-and/or pro-form of the enzyme. Thus, the changes in the density and size of renal lysosomes appear to be associated with the exocytosis of lysosomal enzymes by hPTH(1-34).

Acetylglucosaminidase↗

PubMed1999

Functional role of arg-gly-asp (RGD)-binding sites on beta1 integrin in embryo implantation using mouse blastocysts and human decidua.

Amino acid residues 140-164 of integrin beta1 comprise an Arg-Gly-Asp (RGD) cross-linking region. The present study was undertaken to study the role of the RGD cross-linking region of integrin beta1 subunit in embryo implantation. Decidual cells attached to fibronectin (FN)-coated dishes. A peptide corresponding to integrin beta1[140-164] (DDL; DYPIDLYYLMDLSYSMKDDLENVKS) inhibited decidual cell attachment to FN-coated dishes in a dose-dependent manner. A variant integrin peptide in which Asp 157 and Asp 158 were replaced by Ala (AAL; DYPIDLYYLMDLSYSMKAALENVKS) did not affect decidual cell attachment to FN. Inhibition by DDL peptide was reversed by prior treatment with an RGD-containing peptide but not by prior treatment with an RGE-containing peptide. Mouse blastocysts became attached to cultured human decidual cells after embryos hatched from the zona pellucida. The majority of hatched blastocysts attached to human decidual cells within 24 h of culture. Blastocysts that attached to decidual cells exhibited extensive outgrowth after 48 h. Treatment of decidual cells with synthetic peptides did not affect the rates of hatching and attachment of blastocysts. The outgrowth of embryos on decidual cells was inhibited by DDL peptide in a dose-dependent manner, but not by AAL peptide. These findings suggest that integrin beta1[140-164] on decidual cells may be important in embryonic development and differentiation following attachment.

Amino Acid Sequence↗

PubMed1999

Vascularized fibular graft after excision of giant cell tumor of the distal radius. A case report.

Although hemiarthroplasty of the wrist using vascularized proximal fibula has been described often, long term results with documentation of results are insufficient. A case of giant cell tumor of the distal radius with remarkable extraskeletal extension is reported. Vascularized fibula including its proximal head was used to replace the defect created after en bloc resection of the tumor. There was no deterioration in radiographic findings or function of the new joint at the time of the 10-year followup. Satisfactory range of motion of the wrist and the forearm was maintained. There was no instability in the joint, and grip strength measured 65% of the opposite side. Postoperative magnetic resonance imaging showed survival of the whole graft, including the subchondral portion. In addition to thorough revascularization of the graft, appropriate soft tissue reconstruction using dynamic tendon transfer contributed to the success. When these requirements are fulfilled, the graft can provide a functional and durable result. Although this is a single experience, the authors recommend wrist arthroplasty, rather than arthrodesis, in carefully selected patients.

Adult↗

PubMed1999

Adenovirus-mediated gene transfer of glial cell line-derived neurotrophic factor prevents ischemic brain injury after transient middle cerebral artery occlusion in rats.

To examine a possible protective effect of exogenous glial cell line-derived neurotrophic factor (GDNF) gene expression against ischemic brain injury, a replication-defective adenoviral vector containing GDNF gene (Ad-GDNF) was directly injected into the cerebral cortex at 1 day before 90 minutes of transient middle cerebral artery occlusion (MCAO) in rats. 2,3,5-Triphenyltetrazolium chloride staining showed that infarct volume of the Ad-GDNF-injected group at 24 hours after the transient MCAO was significantly smaller than that of vehicle- or Ad-LacZ-treated group. Enzyme-linked immunosorbent assay (ELISA) for immunoreactive GDNF demonstrated that GDNF gene products in the Ad-GDNF-injected group were higher than those of vehicle-treated group at 24 hours after transient MCAO. Immunoreactive GDNF staining was obviously detected in the cortex around the needle track just before or 24 hours after MCAO in the Ad-GDNF group, whereas no or slight GDNF staining was detected in the vehicle group. The numbers of TUNEL, immunoreactive caspase-3, and cytochrome c-positive neurons induced in the ipsilateral cerebral cortex at 24 hours after transient MCAO were markedly reduced by the Ad-GDNF group. These results suggest that the successful exogenous GDNF gene transfer ameliorates ischemic brain injury after transient MCAO in association with the reduction of apoptotic signals.

Adenoviruses, Human↗

PubMed1999

Myocardial distribution and biotransformation in vitro and in vivo of nicorandil in rats, with special reference to mitochondria.

This study reports subcellular localization of nicorandil in the myocardium and metabolism in mitochondria after oral dosing of 3 mg/kg nicorandil to rats. In the in vitro experiments, nicorandil, which was incubated with tissue homogenates (liver, kidney, heart, and small intestine), was metabolized to its denitrated compound, SG-86, and unknown substances. In the absence of a NADPH-generating system in the heart, the metabolic activity existed only in the mitochondrial fraction, but not in cytosolic and microsomal fractions. In the presence of the system, the activity in the mitochondrial fraction became much higher. To examine subcellular distribution of nicorandil in the myocardium, [14C]nicorandil was orally given to rats. Fifteen minutes after oral dosing of 3 mg/kg [14C]nicorandil, of which myocardial concentration reached a peak, nicorandil and SG-86 were found in mitochondrial fractions as well as in cytosolic and microsomal ones of the heart. Electron-microscopic autoradiograms, 15 min after oral dosing of 3 mg/kg [3H]nicorandil to rats, also showed the existence of the silver grains (showing radioactivity) in mitochondria of the heart. We conclude that nicorandil given orally is distributed in mitochondria of the heart, being partly transformed into SG-86, and that the myocardial mitochondria may be a potential site of action of nicorandil, an opener of KATP channels, which have been demonstrated to be present in this subcellular particle.

Animals↗

PubMed1999

A highly pathogenic simian/human immunodeficiency virus with genetic changes in cynomolgus monkey.

A highly pathogenic simian/human immunodeficiency virus (SHIV), designated C2/1, was obtained by serum passages in cynomolgus monkeys of p-SHIV, an SHIV strain that contains the env gene of pathogenic human immunodeficiency virus type 1 89.6. CD4+ lymphocyte depletion was induced within 1 week of the SHIV-C2/1 infection in peripheral blood as well as in various lymphoid organs in all the animals tested, with symptoms of diarrhoea and no increase in body weight, followed by intense viraemia. Serum antibody against Env protein was detected from 4 weeks after the virus infection, while the anti-Gag antibody response was absent in the SHIV-C2/1-infected animals. In contrast, both anti-Gag and anti-Env antibody responses were present in animals infected with p-SHIV or the non-pathogenic SHIV-MN. Sequencing of the env gene of isolates of SHIV-C strains showed conserved amino acid changes in the Env C2 and V3 regions that included changes to negatively charged amino acids, in the cytoplasmic region of gp41 that included a 42 amino acid deletion, and in the Nef protein. The pathogenic SHIV-C2/1-monkey model suggests that virus-specific pathogenicity in SHIV infection may be associated with the absence of anti-Gag antibody responses in animals and may be caused by genetic changes during serum passage in vivo.

Amino Acid Sequence↗

PubMed1999

Nicorandil, its denitrated metabolite, SG-86 and naturally occurring vasodilators synergistically interact on adenosine-induced vasodepression in rats: special reference to adrenomedullin.

To investigate synergistic effects among nicorandil, its main metabolite, SG-86 and endogenous vasodilators such as adrenomedullin (ADM), vasoactive intestinal polypeptide (VIP) and calcitonin gene-related peptide (CGRP), the effects of ADM, VIP and CGRP as well as nicorandil and SG-86 alone, and their low-dose combination were examined on adenosine-induced vasodepression in anesthetized rats. Single bolus i.v. injections of adenosine (3-100 micrograms/kg) caused a dose-dependent reduction of arterial blood pressure, accompanied by slight decreases (except for 100 micrograms/kg) in heart rate. i.v. infusion of nicorandil (10 micrograms/kg/min), SG-86 (100 micrograms/kg/min) ADM (1 ng/kg/min), VIP (30 ng/kg/min) or CGRP (1 ng/kg/min) alone, or the low-dose combination of either nicorandil (1 microgram/kg/min), and SG-86 (10 micrograms/kg/min) or either nicorandil or SG-86 and endogenous vasodilators, significantly potentiated the vasodepression produced by bolus i.v. adenosine, but not that by bolus i.v. acetylcholine (0.1 microgram/kg). The observed enhancement did not occur in the presence of glibenclamide (20 mg/kg i.v.). The present results indicate that nicorandil, SG-86 and endogenous vasodilators reciprocally interact, partly in link with KATP channels in vascular smooth muscle.

Adenosine↗

PubMed1999

A novel case of a sporadic desmoid tumour with mutation of the beta catenin gene.

A 42 year old man without familial adenomatous polyposis had recurrent desmoid tumours in the left subclavicular site. Histological examination showed a typical desmoid tumour. Molecular analysis was performed in genomic DNA from this tumour, using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and direct sequencing methods. No mutation could be detected in the entire coding sequence of the APC gene, nor in H-ras, K-ras, N-ras, or p53 genes. On seeking a mutation of the beta catenin gene (CTNNB1), an activating mutation from ACC (Thr) to GCC (Ala) at codon 41 was found. Immunohistochemical staining showed that accumulated beta catenin protein was predominantly localised in the nuclei of desmoid cells. This is the first example of a sporadic desmoid tumour in which a mutation of the beta catenin gene was revealed.

Adult↗

PubMed1999

Effects of local inactivation of monkey medial frontal cortex in learning of sequential procedures.

To examine the role of the medial frontal cortex, supplementary motor area (SMA), and pre-SMA in the acquisition and control of sequential movements, we locally injected muscimol into 43 sites in the medial frontal cortex while monkeys (n = 2) performed a sequential button-press task. In this task, the monkey had to press two of 16 (4 x 4 matrix) buttons illuminated simultaneously in a predetermined order. A total of five pairs were presented in a fixed order for completion of a trial. To clarify the differential contribution of the medial frontal cortex for new acquisition and control of sequential movements, we used novel and learned sequences (that had been learned after extensive practice). We found that the number of errors increased for novel sequences, but not for learned sequences, after pre-SMA inactivations. A similar, but insignificant, trend was observed after SMA injections. The reaction time of button presses for both novel and learned sequences was prolonged by inactivations of both SMA and pre-SMA, with a trend for the effect to be larger for SMA inactivations. These findings suggest that the medial frontal cortex, especially pre-SMA, is related to the acquisition, rather than the storage or execution, of the correct order of button presses.

Animals↗

PubMed1999

A novel synthetic anti-acute pancreatitis agent, IS-741.

A novel synthetic drug, IS-741, inhibited cell adhesion in vitro and neutrophil in vivo. Thus, IS-741 inhibited the magnification of pancreatic lesion as well as progression to multiple organ failure in acute pancreatitis models. Furthermore, IS-741 at identical plasma concentrations equally improved the survival rates in animals of various species with severe acute pancreatitis. Based on these observations, it was considered that IS-741 inhibited tissue destruction by neutrophil after inhibiting neutrophil infiltration into the pancreas or other important organs in acute pancreatitis. It was also considered that IS-741 demonstrated various anti-acute pancreatitis effects by interrupting a vicious cycle of inflammation. Therefore, IS-741 is expected to become a useful drug for treating acute pancreatitis and multiple organ failure in clinical settings.

Acute Disease↗

PubMed1999

Synthesis and swelling-deswelling kinetics of poly(N-isopropylacrylamide) hydrogels grafted with LCST modulated polymers.

Two types of thermo-responsive hydrogels are synthesized to obtain comb-type grafted gels with different lower critical solution temperatures (LCSTs) between graft chains and cross-linked backbone networks: these are poly(N-isopropylacrylamide) (PIPAAm) cross-linked hydrogels grafted with poly(N-isopropylacryl amide-co-N,N-dimethylacrylamide) (poly(IPAAm-co-DMAAm)) maintaining a freely mobile end and poly(IPAAm-co-DMAAm) cross-linked hydrogels grafted with PIPAAm chains. The effect of graft chain hydrophilic/hydrophobic balance as well as its mobility on deswelling kinetics of these grafted gels are investigated through the polymer LCST modulation and external temperature changes. The deswelling rate of poly(IPAAm-co-DMAAm)-grafted PIPAAm gel increases with increasing in temperature. This gel shows a discontinuous increase of the deswelling rate when the temperature is applied from below to above the graft chain LCST (37 degrees C). The deswelling rate of PIPAAm-grafted poly(IPAAm-co-DMAAm) gel increases continuously when the temperature is applied from below to above the graft chain LCST (31 degrees C). Due to the strong hydrophilicity of backbone network, the hydrophobic aggregation force weak. In contrast to the graft-type gels, normal-type poly(IPAAm-co-DMAAm) cross-linked gel without graft chains demonstrates the discontinuous decrease for the deswelling rate when the temperature is applied from below to above the polymer LCST (36 degrees C), entrapping water inside the gel due to the formation of an impermeable dense skin layer at the gel surface. These gel deswelling mechanisms are discussed in terms of gel structures.

Absorption↗

PubMed1999

Synthesis and structure-activity relationship of a new series of potent angiotensin II receptor antagonists: pyrazolo[1,5-a]pyrimidine derivatives.

We have already reported 7-oxo-4,7-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylic acid derivatives, which are potent in vitro angiotensin II (AII) antagonists, but have no oral antihypertensive activity. Removal of the carboxylic acid and replacement of the heteroaromatic system afforded potent in vitro antagonists. Removal of the carbonyl oxygen and changing the position of the biphenyltetrazole substituent were critical to the display of oral activity. To improve the in vitro and oral activities, modifications were made of the substituents at the 3- and 5-positions of the pyrazolo[1,5-a]pyrimidine. Structure-activity studies showed the methyl substituent at the 3-position to be essential for potent in vivo activity. We present the design, syntheses, and biological data of a series of pyrazolo[1,5-a]pyrimidine derivatives, which are orally active AII receptor antagonists.

Angiotensin II↗

PubMed1999

Effects of nicorandil on experimentally induced gastric ulcers in rats: a possible role of K(ATP) channels.

The anti-ulcer effects of nicorandil [N-(2-hydroxyethyl)nicotinamide nitrate ester] were examined on water-immersion plus restraint stress-induced and aspirin-induced gastric ulcers in rats, compared with those of cimetidine. Nicorandil (3 and 10 mg/kg) given orally to rats dose-dependently inhibited the development of acid-related damage (water-immersion- and aspirin-induced gastric lesions) in the models. Cimetidine (50 mg/kg, p.o.) also had anti-ulcer effects in the same models. However, in the presence of glibenclamide (20 mg/kg, i.v.), an antagonist of K(ATP) channels, nicorandil did not inhibit the formation of gastric lesions. Nicorandil (10 mg/kg) given intraduodenally (i.d.), like cimetidine (50 mg/kg), significantly reduced the volume of the gastric content, total acidity and total acid output in the pylorus ligation model. Glibenclamide reversed the changes caused by i.d. nicorandil. I.v. infusion of nicorandil (20 microg/kg per min) significantly increased gastric mucosal blood flow, without affecting blood pressure and heart rate, but the increase in the blood flow was not observed after i.v. treatment with glibenclamide (20 mg/kg). These results indicate that nicorandil administered orally to rats produces the anti-ulcer effect by reducing the aggressive factors and by enhancing the defensive process in the mucosa through its K(ATP)-channel-opening property.

Adenosine Triphosphate↗