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Biomedical subjects

J Sakai

Publications and source records attributed to J Sakai.

At least 91 records · Page 5Linked to original sources
PubMed1997

Angiosarcoma of the heart presenting as fatal pulmonary hemorrhage.

A 47-year-old man died from fatal pulmonary hemorrhage. Cardiac angiosarcoma with lung metastases was found at postmortem examination. His chest radiograph showed bilateral, diffuse nodular infiltrates without cardiomegaly. No cardiac signs and symptoms were observed. The clinical outcome was rapidly fatal. Angiosarcoma of the heart should be suspected in patients with hemoptysis and nodular chest radiograph abnormalities, even in the absence of cardiac signs and symptoms.

Fatal Outcome↗
PubMed1997

DISTRIBUTION OF SOMATOSTATIN RECEPTOR TYPE 3 IN THE RAT: IMMUNOHISTOCHEMICAL STUDY.

Somatostatin receptor type 3 (SSTR-3) was identified immunohistochemically in the rat tissues using specific anti-SSTR-3 serum which was raised in New Zealand white rabbits immunized with a conjugate of synthetic SSTR-3 peptide (28-41) with bovine serum albumin. Immunohistochemical analysis was performed by avidin-biotin complex method. SSTR-3 immunoreactivity was visualized in the central nervous system, anterior pituitary, gastric and duodenal mucosa, Auerbach's and Meissner's nervous branch of gastrointestinal tract, adrenal medulla, testis and pancreas. Significant staining was detected in neural perikarya, axons and dendrites. When using antiserum preincubated with synthetic SSTR-3 peptide (28-41) or rat anterior pituitary homogenate which contains SSTR-3 peptide, no significant stain of the anterior pituitary or neurons in the hypothalamus was detected. These findings suggest that SSTR-3 is widely distributed and that this method is valuable in studying the distribution of SSTR-3 in rats.

Journal Article↗
PubMed1997

Organ distribution of iodide transporter (symporter) in the rat: immunohistochemical study.

Iodide transporter/symporter (NIS) was identified immunohistochemically in rat tissues using specific antipeptide serum. Anti-NIS serum was raised in New Zealand white rabbits immunized with a conjugate of synthetic NIS peptide (39-53) with bovine serum albumin. Immunohistochemical analysis was performed by avidine-biotin complex method. NIS immunoreactivity was visualized in the thyroid gland, gastric and small intestine mucosa, anterior pituitary, adrenal medulla, pancreatic islets, kidney, chorioid plexus and several brain and spinal cord nuclei. When using antiserum preincubated with synthetic NIS peptide (39-53) or rat thyroid homogenate containing NIS, no significant stain of the thyroid gland was detected. These findings suggest that NIS is widely distributed and that the method used is suitable for studying the distribution of NIS in rats.

Journal Article↗
PubMed1997

[A study of 44 patients with Kirisawa type uveitis].

We studied 50 eyes of 44 patients with acute retinal necrosis, Kirisawa type uveitis (KU), in order to examine clinical symptoms, pathogenic viruses, clinical grading, therapy and prognosis for this disease. Varicella-zoster virus (VZV) was the pathogenic organism in 37 eyes of 31 patients, while herpes simplex virus (HSV) was responsible in 13 eyes of 13 patients. There were more elderly patients in the VZV-KU group than in the HSV-KU group. In addition, mutton fat keratic precipitates and retinal exudates were more common in VZV-KU than in HSV-KU. We divided KU eyes into 3 clinical grades: severe, serious, and mild. Using statistical analysis, we found that the VZV-KU group had a significantly greater number of severe and serious cases than the HSV-KU group. Furthermore, some HLA antigens were found to be statistically more common in the VZV-KU group, although no associations were found in the HSV-KU group. 32% of VZV-KU and 67% of HSV-KU eyes had a final visual acuity (fVA) of greater than 0.5. When eyes with an fVA of greater than 0.1 were compared to eyes with an fVA of less than 0.1, we found that combined therapy using acyclovir, interferon beta, and prednisolone was especially effective for VZV-KU, although no significant difference was found for HSV-KU. Thus, it is essential to determine the pathogenic virus causing KU, in order to understand the disease pathogenesis as well as to select appropriate treatment.

Adult↗
PubMed1997

[Inhibition of experimental autoimmune uveoretinitis by transforming growth factor-beta 1 in B10. A mice].

Experimental autoimmune uveoretinitis (EAU) in mice, an organ specific autoimmune disease, has been investigated as an animal model for human endogenous uveitis. In this study, we report on the immunosuppressive effect of transforming growth factor-beta 1 (TGF-beta 1) on the development of EAU in mice. Inhibition by TGF-beta 1 of proliferation of interphotoreceptor retinoid-binding protein (IRBP)-specific T cell lines in B10.A mice against IRBP antigen was dose-dependent. However, when spleen cells used as the antigen presenting cell were first cultured with TGF-beta 1, this anti-proliferation effect was abolished. When IRBP-immunized mice were injected intraperitoneally with TGF-beta 1, dose-dependent suppression of EAU was obtained. The proliferation response of lymph node cells from TGF-beta 1 injected mice with IRBP-induced EAU was suppressed compared with phosphate buffered saline (PBS)-injected mice. These findings suggest that TGF-beta 1 may be a cytokine that plays a role in suppressing IRBP induced EAU in mice.

Animals↗
PubMed1996

Sterol-regulated release of SREBP-2 from cell membranes requires two sequential cleavages, one within a transmembrane segment.

Sterol regulatory element binding proteins (SREBPs) are transcription factors attached to the endoplasmic reticulum. The NH2-segment, which activates transcription, is connected to membranes by a hairpin anchor formed by two transmembrane sequences and a short lumenal loop. Using H-Ras-SREBP-2 fusion proteins, we show that the NH2-segment is released from membranes by two sequential cleavages. The first, regulated by sterols, occurs in the lumenal loop. The second, not regulated by sterols, occurs within the first transmembrane domain. The liberated NH2-segment enters the nucleus and activates genes controlling cholesterol synthesis and uptake. Certain mutant Chinese hamster ovary cells are auxotrophic for cholesterol because they fail to carry out the second cleavage; the NH2-segment remains membrane-bound and transcription is not activated.

Amino Acid Sequence↗
PubMed1996

Regulated cleavage of sterol regulatory element binding proteins requires sequences on both sides of the endoplasmic reticulum membrane.

Sterol regulatory element binding proteins (SREBP-1 and SREBP-2) are attached to the endoplasmic reticulum (ER) and nuclear envelope by a hairpin domain consisting of two transmembrane regions connected by a short lumenal loop of approximately 30 hydrophilic amino acids. In sterol-depleted cells, a protease cleaves the protein in the region of the first transmembrane domain, releasing an NH2-terminal fragment of approximately 500 amino acids that activates transcription of genes encoding the low density lipoprotein receptor and enzymes of cholesterol synthesis. In sterol-overloaded cells, proteolysis does not occur, and transcription is repressed. Through mutational analysis in transfected cells, we identify two segments of SREBPs that are required for proteolysis, one on either side of the ER membrane. An arginine in the lumenal loop is essential. A tetrapeptide sequence (DRSR) on the cytosolic face adjacent to the first transmembrane domain is also required for maximal cleavage. Both of these elements are conserved in the human and hamster versions of SREBP-1 and SREBP-2. Sterol-mediated suppression of cleavage of SREBP-1 was found to be dependent on the extreme COOH-terminal region (residue 1034 to the COOH terminus), which exists in two forms as a result of alternative splicing. The form encoded by the "a" class exons (exons 18a and 19a) undergoes sterol-regulated cleavage. The form encoded by the "c" class exons (18c and 19c) is cleaved less efficiently and is not suppressed by sterols. These studies were made possible through use of a vector that achieves low level expression of epitope-tagged SREBPs under control of the relatively weak thymidine kinase promoter from herpes simplex virus. In contrast to SREBPs overproduced by high level expression vectors, the SREBPs produced at low levels were subject to the same regulated cleavage pattern as the endogenous SREBPs. These results indicate that sterol-regulated proteolysis of SREBPs is a complex process, requiring sequences on both sides of the ER membrane.

Alternative Splicing↗
PubMed1996

Defective anion transport and marked spherocytosis with membrane instability caused by hereditary total deficiency of red cell band 3 in cattle due to a nonsense mutation.

We studied bovine subjects that exhibited a moderate uncompensated anemia with hereditary spherocytosis inherited in an autosomal incompletely dominant mode and retarded growth. Based on the results of SDS-PAGE, immunoblotting, and electron microscopic analysis by the freeze fracture method, we show here that the proband red cells lacked the band 3 protein completely. Sequence analysis of the proband band 3 cDNA and genomic DNA showed a C --> T substitution resulting in a nonsense mutation (CGA --> TGA; Arg --> Stop) at the position corresponding to codon 646 in human red cell band 3 cDNA. The proband red cells were deficient in spectrin, ankyrin, actin, and protein 4.2, resulting in a distorted and disrupted membrane skeletal network with decreased density. Therefore, the proband red cell membranes were extremely unstable and showed the loss of surface area in several distinct ways such as invagination, vesiculation, and extrusion of microvesicles, leading to the formation of spherocytes. Total deficiency of band 3 also resulted in defective Cl-/HCO3- exchange, causing mild acidosis with decreases in the HCO3- concentration and total CO2 in the proband blood. Our results demonstrate that band 3 indeed contributes to red cell membrane stability, CO2 transport, and acid-base homeostasis, but is not always essential to the survival of this mammal.

Animals↗
PubMed1996

Human apolipoprotein E receptor 2. A novel lipoprotein receptor of the low density lipoprotein receptor family predominantly expressed in brain.

Isolation and characterization of a human cDNA demonstrated a novel lipoprotein receptor designated apolipoprotein E receptor 2 (apoER2). The new receptor consists of five functional domains resembling the low density lipoprotein (LDL) and very low density lipoprotein (VLDL) receptors. LDL receptor deficient Chinese hamster ovary cells expressing human apoER2 bound apoE rich beta-migrating VLDL with high affinity and internalized. LDL was bound with much lower affinity to these cells. The 4.5- and 8.5-kb mRNAs for the receptor were most highly expressed in human brain and placenta. In rabbit tissues, multiple species of the mRNA with 4, 4.5, 5.5, 8.5, and 11 kb were detected most intensely in brain and testis and, to a much lesser extent, in ovary, but were undetectable in other tissues. In rat adrenal pheochromocytoma PC12 cells, the receptor mRNA was induced by treatment of the cells with nerve growth factor. The receptor transcripts were detectable most intensely in the cerebellar cortex, choroid plexus, ependyma, hippocampus, olfactory bulb and, to a much lesser extent, in the cerebral cortex as revealed by in situ hybridization histochemistry. In the cerebellar cortex, the receptor transcripts were densely deposited in Purkinje cell somata.

Amino Acid Sequence↗
PubMed1996

Cleavage of sterol regulatory element binding proteins (SREBPs) by CPP32 during apoptosis.

Cellular cholesterol homeostasis is controlled by sterol-regulated proteolysis of membrane-bound transcription factors called sterol-regulatory element binding proteins (SREBPs). CPP32, a cysteine protease, was shown previously to cleave SREBP-1 and SREBP-2 in vitro at an aspartic acid between the basic helix-loop-helix leucine zipper domain and the first trans-membrane domain, liberating a transcriptionally active fragment. Here, we show that CPP32 exists in an inactive 32 kDa form in Chinese hamster ovary (CHO) cells. When apoptosis was induced with the protein kinase inhibitor staurosporine, CPP32 was cleaved to subunits of 20 and 10 kDa to form the active protease. Under these conditions membrane-bound SREBP-1 and SREBP-2 were both cleaved, and the transcriptionally active N-terminal fragments were found in nuclear extracts. Similar results were obtained in human U937 cells induced to undergo apoptosis by anti-Fas and etoposide. The apoptosis-induced cleavage of SREBPs was not suppressed by sterols, indicating that apoptosis-induced cleavage and sterol-regulated cleavage are mediated by different proteases. CHO cells expressing a mutant SREBP-2 with an Asp--> Ala mutation at the CPP32 cleavage site showed sterol-regulated cleavage but no apoptosis-induced cleavage. These data are consistent with the emerging concept that CPP32 is a central mediator in apoptosis. They also indicate that SREBPs, like poly (ADP) ribose polymerase, are cleaved by CPP32 during programmed cell death.

Alkaloids↗
PubMed1996

Positive association between a DNA sequence variant in the serotonin 2A receptor gene and schizophrenia.

Sixty-two patients with schizophrenia and 96 normal controls were investigated for genetic association with restriction fragment length polymorphisms (RFLPs) in the serotonin receptor genes. A positive association between the serotonin 2A receptor gene (HTR2A) and schizophrenia was found, but not between schizophrenia and the serotonin 1A receptor gene. The positive association we report here would suggest that the DNA region with susceptibility to schizophrenia lies in the HTR2A on the long arm of chromosomes 13.

Adult↗
PubMed1996

Characterization of the actin cross-linking properties of the scruin-calmodulin complex from the acrosomal process of Limulus sperm.

During activation of the Limulus sperm acrosomal process, actin filaments undergo a change in twist that is linked with the conversion from a coiled to a straight scruin-actin bundle. Since scruin had not been purified, its identity as an actin-binding protein has not been demonstrated. Using HECAMEG (methyl-6-O-(N-heptyl-carbamoyl)-alpha-D-glucopyranoside) detergent extraction in concert with high calcium, we purified native scruin and identified it as an equimolar complex with calmodulin. 125I-Calmodulin overlays and calmodulin-Sepharose indicate that scruin binds calmodulin in calcium but not in EGTA. Overlay experiments also map the calmodulin binding site between the putative N- and C-terminal beta-propeller domains within residues 425-446. Immunofluorescence microscopy reveals that calmodulin colocalizes with scruin and actin in the coiled bundle. Although scruin binds calmodulin, pelleting assays and electron microscopy show that the scruin cross-links F-actin into bundles independently of calcium. Based on our biochemical and structural studies, we suggest a model to explain how scruin controls a change in twist of actin filaments during the acrosome reaction. We predict that calcium subtly alters scruin conformation through its calmodulin subunit and the conformation change in scruin causes a shift in the relative positions of the scruin-bound actin subunits.

Acrosome↗
PubMed1996

Two classes of Tn10 transposase mutants that suppress mutations in the Tn10 terminal inverted repeat.

Tn10 transposition requires IS10 transposase and essential sequences at the two ends of the element. Mutations in terminal basepairs 6-13 confer particularly strong transposition defects. We describe here the identification of transposase mutations that suppress the transposition defects of such terminus mutations. These mutations are named "SEM" for suppression of ends mutations. All of the SEM mutations suppress more than a single terminus mutation and thus are not simple alterations of transposase/end recognition specificity. The mutations identified fall into two classes on the basis of genetic tests, location within the protein and nature of the amino acid substitution. Class I mutations, which are somewhat allele specific, appear to define a small structural and functional domain of transposase in which hydrophobic interactions are important at an intermediate stage of the transposition reaction, after an effective interaction between the ends but before transposon excision. Class II mutations, which are more general in their effects, occur at a single residue in a small noncritical amino-terminal proteolytic domain of transposase and exert their affects by altering a charge interaction; these mutations may affect act early in the reaction, before or during establishment of an effective interaction between the ends.

Codon↗
PubMed1996

Peptide-mediated suppression of experimental autoimmune uveoretinitis in mice: development of a peptide vaccine.

Experimental autoimmune uveoretinitis (EAU) is an animal model of antigen-specific, Th cell-mediated, organ-specific autoimmune disease. EAU is induced by immunization of B10.A mice with interphotoreceptor retinoid-binding protein (IRBP). Pre-treatment with synthetic peptide 518-529 derived from IRBP prevented IRBP-mediated EAU. This was accompanied by augmentation of the IRBP-specific IgG1 antibody (Th2) response and down-regulation of the IRBP-specific IgG2a (Th1) response. Consistent with this is the observation that two of two T cell lines established from p518-529-primed mice produced Th2-type cytokines (IL-4 and IL-10), whereas three of three T cell lines obtained from IRBP-primed mice produced Th1-type cytokines (IL-2 and IFN-gamma). Together this suggests the possibility that p518-529 priming causes a shift from a Th1-to a Th2-dominated immune response, thereby playing a pivotal role in the prevention of IRBP-mediated EAU. Furthermore, co-transfer of cells from a CD4+ p518-529-specific T cell line prevented the development of EAU after adoptive transfer of spleen cells from mice with EAU into normal mice. These findings contribute to our understanding of the mechanism of EAU, particularly with respect to the down-regulation of Th1-initiated inflammation, and may prove valuable for designing a peptide vaccine for EAU in the future.

Adoptive Transfer↗
PubMed1996

The fractional inhibitory concentration index of antimicrobial agents for bacteria and Mycoplasma isolated from the nasal swabs of cattle with respiratory diseases.

We investigated the effect of thiamphenicol plus lincomycin (TP + LCM) and thiamphenicol plus tylosin (TP + TS) combinations using checker board method on the growth of Pasteurella (P.) multocida, P. haemolytica and Mycoplasma (M.) bovis by calculating the fractional inhibitory concentration index (FIC index). The results showed that the FIC indexes of the TP + LCM combination for P. multocida, P. haemolytica and M. bovis were 0.36 +/- 0.10, 0.72 +/- 0.09 and 0.81 +/- 0.18, respectively. The FIC indexes of the TP + TS combination for P. multocida, P. haemolytica, and M. bovis were 0.79 +/- 0.20, 0.66 +/- 0.11 and 0.32 +/- 0.14, respectively. Thus, these combinations are assumed to have a more synergistic or additive effect on bacteria growth than a single antimicrobial agent.

Animals↗
PubMed1996

Effect of a combination of antimicrobial agents for the treatment of respiratory disease in cattle.

Clinical effect of the administration of thiamphenicol (TP) and tylosin (TS) on bovine respiratory disease was investigated. Group I (n = 64) were administered TP (10 mg/kg) and TS (4 mg/kg), group II (n = 26) were given TP (5 mg/kg) and TS (2 mg/kg). For the control, TP group (n = 25) were given 20 mg/kg of TP and ampicillin group (n = 23) were given 10 mg/kg of ampicillin. As a result, improvement of clinical findings was more rapid and the cure rate was significantly higher in group I compared to those in the other 3 groups. These results showed that a combination therapy with minimal basic doses of TP and TS is very effective for some respiratory diseases in cattle.

Animals↗
PubMed1996

Distribution of somatostatin receptor type 2 in the rat: immunohistochemical study.

Somatostatin receptor type 2 (SSTR-2) was identified immunohistochemically in the rat tissues using specific antipeptide antiserum raised in New Zealand white rabbits immunized with a conjugate of synthetic SSTR-2 peptide (31-41) with bovine serum albumin. Immunohistochemical analysis was performed by avidin-biotin complex method. SSTR-2 immunoreactivity was visualized in the central nervous system and anterior pituitary thus supporting previous investigations of SSTR-2 distribution using in vitro autoradiographic ligand binding. Significant stain was detected in neural perikarya, axons and dendrites as well as in many cells of retina, adrenal medulla, gastric and duodenal mucosa, Auerbach's nervous branch and Meíssner's nervous branch of the stomach, small intestine and colon. When using antiserum preincubated with synthetic SSTR-2 peptide (31- 41) or rat anterior pituitary homogenate which contains SSTR-2 peptide, no significant stain of the anterior pituitary or neurons in the hypothalamus was detected. These findings suggest that SSTR-2 is widely distributed and that the method used is valuable in studying the distribution of SSTR-2 in rats.

Journal Article↗