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K Sakai

Publications and source records attributed to K Sakai.

At least 577 records · Page 32Linked to original sources
PubMed1995

Expression of messenger RNA encoding a paraneoplastic cerebellar degeneration-associated antigen in the rat hippocampus.

The PCD17 protein is a paraneoplastic cerebellar degeneration (PCD)-associated neural autoantigen which is recognized by autoantibodies in sera of PCD patients. The localization of the PCD17 mRNA was examined by in situ hybridization histochemistry using a PCD17 cRNA probe. In the cerebellum, the localization of the transcript was in agreement with the distribution of PCD17-immunoreactivity. On the other hand, intense hybridization signals were detected in most of cells in the hippocampus in which notable PCD17-immunoreactivity was undetected. These observations suggest that some negative translational or post-transcriptional mechanisms of the PCD17 mRNA may be involved in neurons of the hippocampus.

Animals↗
PubMed1995

Functional mapping of the human colour centre with echo-planar magnetic resonance imaging.

Clinical studies of cerebral achromatopsia have suggested a colour centre in the human fusiform gyrus. By using functional magnetic resonance imaging, we examined whether the fusiform gyrus shows activity correlated with the perception of colour. We tested three stimulus conditions in which the subject maintained fixation: (i) a circular array of six coloured circles; (ii) the same as (i) except that each circle is equiluminant grey with its colour counterpart; and (iii) the same as (i) plus a clockwise shift of circles to neighbouring positions every 1 s. After termination of the stimulus, the subject perceived an after-image of circles with complementary colours in (i), but not in (iii). In condition (i), we found a focal signal increase in the posterior part of the fusiform gyrus. In condition (ii), the activation in the same locus during the stimulation period was weaker than that in (i). In condition (iii), the signal intensity after termination of the stimulus was weaker than that in (i). The colour effect and after-effect on activation of the fusiform gyrus observed here suggest its critical role in human colour perception.

Brain Mapping↗
PubMed1995

Cloning and expression of cDNA encoding a new type of ascorbate peroxidase from spinach.

A cDNA clone (SAP1) encoding a peroxidase was isolated from a spinach cDNA library using monoclonal antibodies raised against Euglena ascorbate peroxidase. The deduced amino acid sequence of SAP1 had higher homology with the cytosolic ascorbate peroxidases from plant sources than with bacterial peroxidases and classical plant peroxidases. The peroxidase activity of recombinant SAP1 protein expressed in E. coli was 1.6-fold higher with ascorbate than with guaiacol, which was similar to those of endogenous cytosolic ascorbate peroxidases. Here we conclude that SAP1 belongs to a new type of ascorbate peroxidase from spinach.

Amino Acid Sequence↗
PubMed1995

Quantitation of tryptase, chymase, Fc epsilon RI alpha, and Fc epsilon RI gamma mRNAs in human mast cells and basophils by competitive reverse transcription-polymerase chain reaction.

Competitive reverse transcription-PCR assays developed for human tryptase, chymase, Fc epsilon RI alpha, and Fc epsilon RI gamma mRNA molecules were applied to the HMC-1 leukemic mast cell line, the KU812 leukemic basophil cell line, mast cells dispersed from lung and skin, and peripheral blood basophils. Relative amounts of alpha-tryptase and beta-tryptase mRNA were determined by analysis of BseAI digests of PCR products. Tryptase expression was highest in tissue-derived mast cells, lowest in basophils and KU812 cells, and intermediate in HMC-1 cells. beta-Tryptase mRNA predominated in HMC-1 and KU812 cells; mixtures of alpha- and beta-tryptase were found in tissue mast cells; and alpha-tryptase predominated in basophils. Chymase mRNA was more abundant in skin-derived (nearly all of the MCTC type) than lung-derived (variable amounts of MCTC and MCT cells) mast cells. Small amounts of chymase mRNA were detected in HMC-1 cells; none was found in basophils, in KU812 cells, or in the one preparation of 100% MCT cells derived from lung. Comparable amounts of Fc epsilon RI alpha and Fc epsilon RI gamma mRNA molecules were measured in basophils and tissue-derived mast cells, lesser amounts were detected in KU812 cells, and almost none was detected in HMC-1 cells. Thus, steady state levels of the granule and membrane resident molecules examined in our study are transcriptionally regulated in mast cells and basophils.

Base Sequence↗
PubMed1995

Human ribosomal RNA gene cluster: identification of the proximal end containing a novel tandem repeat sequence.

Human ribosomal RNA genes (rDNA) are arranged as tandem repeat clusters on the short arms of five pairs of acrocentric chromosomes. We have demonstrated that a majority of the rDNA clusters are detected as 3-Mb DNA fragments when released from human genomic DNA by EcoRV digestion. This indicated the absence of the EcoRV restriction site within the rDNA clusters. We then screened for rDNA-positive cosmid clones using a chromosome 22-specific cosmid library that was constructed from MboI partial digests of the flow-sorted chromosomes. Three hundred twenty rDNA-positive clones negative for the previously reported distal flanking sequence (pACR1) were chosen and subjected to EcoRV digestion. Seven clones susceptible to EcoRV were further characterized as candidate clones that might have been derived from the junctions of the 3-Mb rDNA cluster. We identified one clone containing part of the rDNA unit sequence and a novel flanking sequence. Detailed analysis of this unique clone revealed that the coding region of the last rRNA gene located at the proximal end of the cluster is interrupted with a novel sequence of approximately 147 bp that is tandemly repeated and is connected with an intervening 68-bp unique sequence. This junction sequence was readily amplified from chromosomes 21 and 15 as well as 22 using the polymerase chain reaction. Fluorescence in situ hybridization further indicated that the approximately 147-bp sequence repeat is commonly distributed among all the acrocentric short arms.

Animals↗
PubMed1995

Tissue-specific suppression of aortic fatty-acid-binding protein in streptozotocin-induced diabetic rats.

Fatty-acid-binding protein (FABP) expressed in rat aorta has been shown to be homologous to heart FABP (H-FABP) but its precise primary structure, cellular localization and function are not known. To establish the nucleotide identity between heart and aorta FABP, we performed an RNase protection assay with antisense RNA of rat H-FABP. The results demonstrate that the primary nucleotide sequence of aortic FABP is identical to that of rat H-FABP. In situ hybridization analysis revealed that aortic H-FABP mRNA is present in both smooth muscle cells and endothelial cells. In order to explore the function of aortic H-FABP, we examined whether a quantitative change in aortic H-FABP occurred in diabetes mellitus, since this pathological state has been shown to cause abnormalities in fatty acid metabolism. Northern blot analysis revealed that the level of aortic H-FABP mRNA was markedly decreased in rats made diabetic by streptozotocin treatment. The suppression of the mRNA level paralleled that of the protein level, as assessed by Western blot analysis. In distinct contrast, no major changes in the H-FABP mRNA level were observed in any other tissues examined, including heart, kidney and skeletal muscle, suggesting that this decrease is highly tissue-specific. The suppression of the aortic H-FABP in streptozotocin-diabetic rats was abolished by insulin supplementation. Taken together, these results suggest that the expression of the H-FABP gene in aorta may be specifically and dramatically suppressed in streptozotocin-diabetic rats, and that this suppression appears to be regulated by insulin.

Animals↗
PubMed1995

Concurrent radiotherapy and chemotherapy with protracted continuous infusion of 5-fluorouracil in inoperable esophageal squamous cell carcinoma.

PURPOSE: The feasibility of a concurrent chemoradiotherapeutic protocol for patients with inoperable esophageal squamous cell carcinoma was tested. METHODS AND MATERIALS: Concurrent chemoradiotherapy using protracted low-dose continuous infusions of five-fluorouracil (5-FU; 250-300 mg/m2/24 h) and standard external beam irradiation was given to 28 patients with inoperable esophageal squamous cell carcinoma between November 1991 and June 1993. RESULTS: For 25 patients receiving a total dose of > or = 60 Gy and concurrent 5-FU infusion for more than 5 weeks, the complete response rate was 52%. Local progression-free rate in this chemoradiotherapy group was significantly higher than the historical controls treated by radiotherapy alone (p < 0.05). A multivariate analysis revealed the treatment scheme (concomitant chemoradiotherapy vs. radiotherapy alone) to be a significant factor in local control (p < 0.01). Swallowing pain (39%), anorexia (39%), and nausea (32%) were the most frequent early reactions. Serious late radiation complications have not been observed. CONCLUSION: The concurrent chemoradiotherapy using protracted low-dose continuous infusion of 5-FU and standard radiotherapy is an effective and safe method to obtain a local control in inoperable esophageal squamous cell carcinoma.

Aged↗
PubMed1995

Sprouting of dopaminergic fibers from spared mesencephalic dopamine neurons in the unilateral partial lesioned rat.

A unilateral partially lesioned rat model of Parkinson's disease was developed following selective lesioning of the dopamine neurons of the substantia nigra pars compacta by stereotactic injection of the neurotoxin 6-hydroxydopamine. In this animal model the dopamine neurons of the ventral tegmental area and medial substantia nigra are spared. The neuronal loss in such partial lesioned models mimics more closely that seen in human mid-stage parkinsonism. Cografts of adrenal medullary cells and sciatic nerve to the partially lesioned striatum induced a sprouting response in grafted animals that was confirmed by immunocytochemical staining with antibodies to tyrosine hydroxylase (TH) and by quantification of the high affinity dopamine uptake complex using [3H]GBR 12935 binding. Enhanced TH fiber immunostaining was evident even in the presence of poor cograft survival. The origin of the TH-like immunostained fibers in the striatum was determined using Lucifer yellow retrograde axonal transport. Following discrete tracer injections into the striatum adjacent to a cograft, neurons in the medial substantia nigra and ventral tegmental area (areas A9 and A10, respectively) were labeled with Lucifer yellow. These labelled neurons displayed a morphology characteristic of dopamine neurons and, in double-labelling experiments, also immunostained for TH. These results support the utility of unilateral partially lesioned rat models of Parkinson's disease for studies investigating a host sprouting or upregulation response and confirm that the immunostained striatal fibers originate from spared dopamine neurons in the ventromedial midbrain.

Animals↗
PubMed1995

Kainate receptors: a novel mechanism in paradoxical (REM) sleep generation.

Application of kainate to the peri-locus coeruleus alpha (peri-LC alpha) resulted in a marked increase in paradoxical sleep (PS). This effect was completely blocked by specific non-NMDA receptor antagonists, but not by selective NMDA receptor antagonists. Kainate was 10 times more potent than AMPA, and their site of action was confined to the peri-LC alpha. This study is the first to show that excitatory amino acids play an important role in PS generation via the activation of kainate receptors which are located in the peri-LC alpha of the mediodorsal pontine tegmentum.

Animals↗
PubMed1995

One-stage treatment of infected bone defects of the tibia with skin loss by free vascularized osteocutaneous grafts.

Twenty-six patients who had an infected nonunion or segmental defect of the tibia with skin loss were treated in one stage with debridement and a free vascularized osteocutaneous fibula or iliac graft. Successful control of infection, closure of skin defects, and incorporation of bone union were achieved in all patients except one. In an average follow-up of 39 months, no recurrence of infection was seen. There were four stress fractures of the grafted fibula; these healed within 2 months with cast immobilization. Graft hypertrophy was common in the fibula grafts, but it took 1 1/2 years for hypertrophy of the graft to be strong enough to remove external supports without stress fracture or an additional cancellous bone graft. The use of a one-stage free vascularized osteocutaneous graft for the management of infected bone defects of the tibia with skin loss is effective because extensive debridement can remove all devitalized and infected tissue and can increase vascularity in the region of infection and osseous defect to enhance antibiotic delivery.

Adult↗
PubMed1995

Functional mapping of the human somatosensory cortex with echo-planar MRI.

The somatotopical organization of the human somatosensory cortex was analyzed with echo-planar imaging at 1.5 Tesla, utilizing deoxyhemoglobin as an endogenous contrast medium. Scrubbing stimulation at a frequency of 3 Hz was applied to one of three cutaneous areas: toes, fingertips, and tongue tip. Parasagittal echo-planar slices were obtained every 2 s. We found focal bands of increased signal intensity (4% on average) during the stimulation, with a rise time of 2-6 s. These activated bands were located on the contralateral postcentral gyrus. The cortical responses from the three stimulation sites were anatomically distinct and organized medially-to-laterally in the order of toes, fingertips, and tongue tip.

Adult↗
PubMed1995

Adhesion molecules on intermediate TCR cells. II. Hepatoprotective effects of hyaluronic acid on acute liver injury.

The liver is a major organ wherein extrathymic T cells and NK cells exist in mice. Due to their unique properties, i.e., extrathymic T cells are TCR (or CD3)-intermediate+ IL-2R beta+ (herein termed intermediate TCR cells) and NK cells are TCR(-)IL-2R beta+, they are easily distinguished from the other lymphocyte subsets by using mAbs in conjunction with immunofluorescence tests. They were recently found to express a higher level of CD44 antigen, which is a ligand for hyaluronic acid, than that of another T cell subset (i.e., thymus-derived T cells or bright TCR cells). Since an intravenous administration of hyaluronic acid was also found to reduce the number of intermediate TCR cells and NK cells in the liver, we examined whether hyaluronic acid had a hepatoprotective effect on acute liver injury. Such injury was induced by LPS injection in mice pretreated with Propionibacterium acnes 1 week earlier. When a single dose of hyaluronic acid was given to these mice 12 hr before LPS injection, a prominent hepatoprotective effect was observed in terms of decreases of mortality (up to 50%), lymphocyte infiltration of the liver, serum transaminase levels, and tissue damage. At this time, liver mononuclear cells isolated from the treated mice showed decreased levels of cytokine production such as TNF and IL-1. These results reveal that intermediate TCR cells and NK cells in the liver actually adhere the sinusoid walls by means of an interaction of CD44 molecules and hyaluronic acid even in the case of acute liver injury. It suggests a possible therapeutic effect of the administration of hyaluronic acid in acute liver injury by eliminating the effector cells and cytokine-producing cells from the liver.

Adjuvants, Immunologic↗
PubMed1995

Increases in cortical neuropeptide Y and somatostatin concentrations following haloperidol-depot treatment in rats.

The concentrations of neuropeptide Y (NPY) and somatostatin (SS) have been said to be altered in the brain and cerebrospinal fluid of schizophrenic patients. This alteration could result from the neuroleptic treatment. Therefore, it is of interest to evaluate effects of long-term treatment with neuroleptics on the peptide concentrations in the brain. Haloperidol (HPD) is one of the most frequently used neuroleptics for the treatment of schizophrenia. We determined regional brain levels of NPY and SS following HPD administration in the rat. A single intraperitoneal injection of HPD, at a dose of 1 mg/kg, did not affect peptide levels in the brain regions studied. Four weeks after an intramuscular deposit injection of HPD decanoate, 50 mg/kg, NPY concentrations were increased in a number of areas of the cerebral cortex. SS content was also significantly increased in the lateral prefrontal cortex and anterior cingulate cortex. Both peptide levels were decreased in the striatum. These results suggest that the reduction found in these peptides' levels in the cerebral cortex of the brain from schizophrenic patients may not be the consequence of HPD treatment and that these peptides' levels might be increased in the cerebral cortex of the brain of schizophrenic patients following the treatment with HPD.

Animals↗
PubMed1995

Induction of anti-Purkinje cell antibodies in vivo by immunizing with a recombinant 52-kDa paraneoplastic cerebellar degeneration-associated protein.

We immunized five different strains of mice with the recombinant human PCD17 protein, which is recognized by anti-Purkinje cell antibodies in the sera of patients with paraneoplastic cerebellar degeneration, and explored whether or not antibodies against cerebellar Purkinje cells could be induced in vivo. Autoantibodies against the cytoplasmic protein of Purkinje cells and other neurons were raised in all the strains of mice. These antisera stained the cytoplasm of cytoplasm of the Purkinje cell in a coarse, granular pattern, but spared the nucleus. The antisera did not stain cerebellar granular cells. This pattern of immunostaining seen with the mouse antisera is similar to that seen with the human PCD sera, but more widespread cells in the central nervous system were stained with these antisera. The titers of the induced antibodies were comparable to or even higher than those of humans. The deposition of IgG was also demonstrated in the cytoplasm of Purkinje cells in the immunized mice. In spite of the generation of anti-Purkinje cell antibodies in vivo, neither clinical nor pathological changes consistent with cerebellar degeneration were detected 1 year following the first immunization.

Animals↗
PubMed1995

Effect of decerebration on blood pressure during paradoxical sleep in cats.

We investigated the effects of decerebration on long-term variations in arterial blood pressure during paradoxical sleep (PS) in cats. In normal cats, the blood pressure decreased during the transition from slow wave sleep to PS and maintained its lower level throughout PS for several days after surgery. After this early postoperative stage, however, the arterial hypotension was replaced by tonic and phasic rises in blood pressure during PS. Such long-term changes in blood pressure were completely abolished when the brain stem was transected at the ponto-mesencephalic junction, and the cats consistently exhibited a sustained fall in blood pressure throughout the survival periods of 1 month or more.

Animals↗