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Biomedical subjects

S Miyata

Publications and source records attributed to S Miyata.

At least 91 records · Page 5Linked to original sources
PubMed1999

Low phagocytic activity of resident peritoneal macrophages in diabetic mice: relevance to the formation of advanced glycation end products.

Formation of advanced glycation end products (AGEs) is accelerated in diabetic subjects along with hyperglycemia. Although several lines of evidence indicate that AGEs stimulate macrophages to secrete several cytokines and growth factors, little is known about the effect of AGEs on the primary function of macrophages, such as phagocytosis. On the other hand, impairment of the phagocytic function of monocytes/macrophages is suggested to contribute to the low resistance to infection in diabetic subjects. In the present study, we examined the effect of AGEs on the phagocytic function of macrophages. Using flow cytometric analysis of mouse resident peritoneal macrophages, we showed that AGEs suppress phagocytosis of fluorescent microspheres by cultured macrophages. In addition, experiments using streptozotocin-induced diabetic mice demonstrated a significant decrease in the phagocytic activity of resident peritoneal macrophages 12 weeks after induction of diabetes compared with age-matched control mice. The phagocytic activity of peritoneal macrophages correlated inversely with AGE content in the adjacent peritoneal tissue. Furthermore, reduced phagocytic activity of macrophages was associated with a reduction in intracellular ATP content. Because phagocytosis is an important component of the defense system, suppression of such activity by AGEs may explain, at least in part, the increased susceptibility of diabetic patients to infection.

Adenosine Triphosphate↗
PubMed1999

[Postoperative recurrent laryngeal nerve palsy following a transesophageal echocardiography].

The postoperative recurrent laryngeal nerve palsy (RLNP) following transesophageal echocardiography (TEE) was retrospectively evaluated in 175 adult patients after cardiac surgery. The incidence of RLNP was not significantly different between TEE group and non TEE group, but the incidence in female TEE group was higher than that in female non TEE group. The mechanism of RLNP following TEE as well as the insertion of nasogastric tube may be compression injuries of the branches of the posterior division of the recurrent laryngeal nerves. The incidence of RLNP in female TEE group was higher because of the narrow female larynx. TEE is a useful monitor during cardiac surgery, but we must be careful about RLNP following TEE.

Aged↗
PubMed1999

The alteration of nasal resistance before and after local exposure to heated aerosol in perennial allergic rhinitis.

To determine the patho-physiological effects of heated vapour to the normal or allergic nasal mucosa, we measured the nasal resistance before and after a 10 min. exposure of hyperthermal (43.0 degrees C) aerosol to the nasal mucosa in normal subjects and perennial allergic rhinitis patients. In the allergic patients the mean nasal resistances after hyperthermal stimulation were significantly higher than those resistances without stimulation, both in expiration or inspiration. No significant differences of nasal resistances in normal individuals during the whole schedule with and without heated aerosol stimulation were found on expiration or inspiration. The local heated aerosol exposure increases the nasal resistance in nasal allergic patients while in normal subjects no changes were found, and the reaction may have arisen from a non-specific hypersensitivity of the susceptible allergic nasal mucosa.

Administration, Inhalation↗
PubMed1999

Shear-dependent functions of the interaction between soluble von Willebrand factor and platelet glycoprotein Ib in mural thrombus formation on a collagen surface.

Recent flow studies have clearly established the function of von Willebrand factor (vWF) in initial platelet adhesion, in which the interaction of surface-immobilized vWF with platelet glycoprotein (GP) Ib, particularly at high shear rates, leads to the transient capture of flowing platelets onto the surface. This interaction is thought to trigger activation of platelet GP IIb/IIIa, leading to irreversible platelet adhesion and subsequent mural thrombus growth. The role of vWF-GP Ib interaction in secondary thrombus growth remains to be clarified, however. In this study, time-course images of the thrombus formation process were obtained using a whole blood flow system that allows real-time visualization of fluorescence-labeled platelet thrombus formation. The system employs a collagen-coated surface in a parallel plate flow chamber mounted on an epifluorescence microscope, which is then subjected to computer-assisted image analysis. In perfusion of blood preincubated with anti-vWF antibody NMC-4, which blocks the vWF-GP Ib interaction in solution, neither primary platelet adhesion nor subsequent thrombus growth on a collagen surface was detected at high shear rates (> or = 1210/s). In addition, even under experimental conditions in which initial platelet adhesion normally occurred, NMC-4-treated blood perfusion showed an apparent defect of secondary thrombus growth at the same high shear rates. The overall process of thrombus formation at low shear rates (< or = 340/s) was not affected by specific blockers of the vWF-GP Ib interaction. These findings indicate that, in addition to the interaction of surface-immobilized vWF with GP Ib in platelet adhesion, the interaction of soluble vWF with GP Ib is required for secondary thrombus growth selectively at high shear rates.

Antibodies, Monoclonal↗
PubMed1998

Novel alternative splicing in the 5' exon of the neurotrophin-3 gene.

The neurotrophin-3 (NT-3) gene has previously been reported to consist of three exons including two 5' short untranslated exons and a 3' long exon encoding the entire protein, and to give rise to two classes of transcripts by alternative splicing of the 5' exons to the 3' coding exon. In the present study, we demonstrated the presence of at least four new classes of transcripts of the NT-3 gene, in addition to the two known transcripts. The present finding proposes the further complexity of the regulational mechanism for NT-3 expression.

Alternative Splicing↗
PubMed1998

Characterization of genes for two-component phosphorelay mediators with a single HPt domain in Arabidopsis thaliana.

Three cDNAs that encode two-component phosphorelay-mediator-like proteins were cloned from Arabidopsis thaliana. Putative proteins (ATHP1-3) contain an HPt (Histidine-containing Phospho transfer)-like domain with a conserved histidine and some invariant residues that are involved in phosphorelay. Growth retardation of YPD1-disrupted yeast cells was reversed with ATHPs, which indicates that ATHPs function as phosphorelay mediators in yeast cells. The ATHP genes are expressed more in roots than in other tissues, similar to the expression of genes for a sensor histidine kinase, ATHK1, and response regulators ATRR1-4. These results suggest that ATHPs function as two-component phosphorelay mediators between sensor histidine kinase and response regulators in Arabidopsis.

Amino Acid Sequence↗
PubMed1998

Mucin gene (MUC 2 and MUC 5AC) upregulation by Gram-positive and Gram-negative bacteria.

Bacterial infection of the lung is associated with mucin overproduction. In partial explanation of this phenomenon, we recently reported that supernatant from the Gram-negative organism Pseudomonas (P.) aeruginosa contained an activity that upregulated transcription of the MUC 2 mucin gene [J.-D. Li, A. Dohrman, M. Gallup, S. Miyata, J. Gum, Y. Kim, J. Nadel, A. Prince, C. Basbaum, Transcriptional activation of mucin by P. aeruginosa lipopolysaccharide in the pathogenesis of cystic fibrosis lung disease, Proc. Natl. Acad. Sci. U.S.A., 94 (1997) 967-972]. The purpose of the present study was to determine whether mucin genes other than MUC 2 are so regulated and whether Gram-positive organisms also contain mucin stimulatory activity. Results from in situ hybridization and RNase protection assays showed that P. aeruginosa upregulates MUC 5AC as well as MUC 2 in both bronchial explants and cultured airway epithelial cells. The upregulation of both genes by P. aeruginosa can be mimicked by lipopolysaccharide (LPS) and can be blocked by the tyrosine kinase inhibitor genistein. In addition, both genes are upregulated by a variety of Gram-positive as well as Gram-negative organisms showing the same rank order of potency. These data indicate the existence of a general mechanism by which epithelial cells respond to the presence of bacteria by increasing mucin synthesis.

Bronchi↗
PubMed1998

Gene expression of neurotrophins and their receptors in cultured rat vascular smooth muscle cells.

Most previous researches on neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) have focused on the nervous system, because their receptors are widely distributed in neuronal tissues. Recently, however, the participation of neurotrophins in inflammation and atherosclerosis has been proposed. Therefore, the gene expression of neurotrophins is now an urgent issue is to be investigated in nonneuronal tissues. Here, we evaluated the gene expression of neurotrophins and their receptors in rat cultured vascular smooth muscle cells (VSMCs) by the reverse transcriptase-polymerase chain reaction method. The transcripts of NGF, NT-3, and TrkC (high-affinity receptor for NT-3), and two BDNF alternative spliced transcript variants with exons 3 and 4 were clearly detected in VSMCs cultured under conventional culture conditions. The upregulation of mRNA levels for NGF, two BDNF variants with exons 1 and 2, low-affinity neurotrophin receptor, and high-affinity receptors, TrkA (for NGF) and TrkB (for BDNF), was observed in response to the treatment with serum and phorbol-ester following the serum-starvation. In contrast, the expression of NT-3 and TrkC genes was downregulated under these conditions. Co-expression of these factors and their receptors and the characteristic regulation of their gene transcriptions suggest that these factors play crucial roles in the function of VSMCs through an autocrine mechanism.

Alternative Splicing↗
PubMed1998

Metabolic mapping of the brain in pregnant, parturient and lactating rats using fos immunohistochemistry.

The present study was designed to investigate Fos-positive neurons of the female rat brain at various reproductive states in order to analyze the metabolic map connected with pregnancy, parturition and lactation. The number of Fos-positive neurons in each brain nucleus was analyzed with a quantitative immunohistochemical method in virgin, pregnant, parturient, lactating and arrested lactating rats. In parturient rats, a significant number of Fos-positive neurons was observed as compared to virgin or pregnant females in the following brain regions; the bed nucleus of the stria terminalis (BST), lateral septal nucleus (LS), medial preoptic area (MPA), periventricular hypothalamic nucleus (Pe), parvocellular paraventricular hypothalamic nucleus (PaPVN), magnocellular paraventricular hypothalamic nucleus (MaPVN), supraoptic nucleus (SON), paraventricular thalamic nucleus (PV), anterior hypothalamic area (AHA), lateral hypothalamic area (LH), amygdaloid nucleus (AM), supramammillary nucleus (SuM), substantia nigra (SN), central grey (CG), microcellular tegmental nucleus (MiTg), subparafascicular thalamic nucleus (SPF), posterior hypothalamic area (PH), dorsal raphe nucleus (DR), locus coeruleus (LC), dorsal parabrachial nucleus (DPB), nucleus of solitary tract (Sol), and ventrolateral medulla (VLM). Significant differences were found in the number of Fos-positive neurons between parturient and lactating females, although localization of Fos-positive neurons in lactating females was quite similar to parturient ones. Between parturient and lactating rats: (1) In the MPA, PaPVN, AHA, arcuate hypothalamic nucleus (Arc), ventromedial hypothalamic nucleus (VMH), MLT, and Ge, the number of Fos-positive neurons of lactating females were significantly higher than those of parturient ones; (2) In the LS, Pe, PV, LH, AM, SuM, CG, MiTg, SPF, PH, DR, LC, and VLM, there was no significant differences in the number of Fos-positive neurons; (3) In the BST, MaPVN, SON, SN, DPB and Sol, the number of Fos-positive neurons of lactating rats were significantly lower than those of parturient ones. These different patterns of Fos expression among many brain regions may be owing to the functional differences in each region. Fos expression in lactating rats was apparently induced by suckling stimulation because the removal of their litters immediately after parturition completely eliminated expression of Fos protein in each nucleus. These results suggest that the localization of Fos-positive neurons in a number of neural populations throughout the brain may be revealing the neural circuits in response to parturition or lactation.

Animals↗
PubMed1998

Colocalization of calretinin and calbindin-D28k with oxytocin and vasopressin in rat supraoptic nucleus neurons: a quantitative study.

Recent electrophysiological experiments, in which purified calbindin-D28k (calbindin) and calretinin antibodies were diffused into these neurons, showed that Ca2+-dependent membrane potentials and firing patterns were profoundly and predictably affected by Ca2+-binding proteins (CaBPs). The present study used quantitative analyses of a dual-labeling immunofluorescence method to investigate the colocalization of the CaBPs, calbindin and calretinin in oxytocin (OT)- and (VP)-containing neurons of the supraoptic nucleus. Analyses of tissue immunostained with two different dilutions of each CaBP antibody used, revealed that 84% and 72% of the OT neurons were positive for calbindin immunoreactivity (-ir) at the higher and lower antibody concentrations, respectively. 52% and 50% of OT neurons were positive for calretinin-ir; thus, many OT neurons express both calbindin and calretinin. In contrast, only 25% and 18% of VP neurons showed calbindin-ir, and they were virtually devoid of calretinin-ir. These results provide evidence that CaBP expression in OT neurons is both greater and more diverse than in VP neurons, and are consistent with the hypothesis that Ca2+ buffering capacity contributes to the control of intrinsic firing patterns.

Analysis of Variance↗
PubMed1998

cDNA cloning of a novel trypsin inhibitor with similarity to pathogenesis-related proteins, and its frequent expression in human brain cancer cells.

A novel trypsin inhibitor (P25TI) with an apparent molecular size of 25 kDa has previously been purified from the culture medium of human glioblastoma cells. In this study, the cDNA encoding P25TI was isolated by the polymerase chain reaction (PCR) screening system, and its complete amino acid sequence was determined. The cDNA consisted of 1440 nucleotides and encoded a sequence of 258 amino acids. The deduced structure of P25TI seemed to consist of a putative signal peptide sequence (residues 1-25), a propeptide sequence (26-60) and a mature protein (residues 61-258). The P25TI sequence has no homology to other proteinase inhibitors, but has similarity to insect venom allergens, mammalian testis-specific proteins and plant pathogenesis-related proteins. P25TI mRNA was frequently expressed in human neuroblastoma and glioblastoma cell lines. Although Northern blotting analysis failed to detect P25TI mRNA in various human tissues, PCR analysis showed its expression in the brain, placenta and lymphocytes.

Amino Acid Sequence↗
PubMed1998

Transcription of plastid-derived tRNA genes in rice mitochondria.

Previous investigations located nine of the genes for rice tRNAs on plastid (pt)-derived sequences in mitochondrial DNA. In the present study, we examined whether these genes were also transcribed in rice mitochondria. Northern-blot hybridization revealed that seven of these genes (trnC, trnF, trnH, trnM, trnN, trnS and trnW) are transcribed and are precisely processed to mature tRNAs. One of the other two genes (trnP) is transcribed but cannot be processed efficiently, while the other (trnR), which has 100% identity to the original plastid tRNAArg gene, is not transcribed in rice mitochondria. These results suggest that seven of the nine pt-derived tRNAs may be utilized for the biosynthesis of protein in plant mitochondria.

DNA Probes↗
PubMed1998

Expression of trypsin by epithelial cells of various tissues, leukocytes, and neurons in human and mouse.

It has long been believed that trypsin is normally synthesized only in the pancreas. In the present study, expression of trypsin in human and mouse nonpancreatic tissues was examined. Northern blot analysis of normal human tissues indicated that the trypsin gene is expressed at high levels in the pancreas and spleen and considerably in the small intestine. However, in situ hybridization and immunohistochemistry demonstrated that trypsin is widely expressed in epithelial cells of the skin, esophagus, stomach, small intestine, lung, kidney, liver, and extrahepatic bile duct, as well as splenic and neuronal cells. In the spleen, trypsin message was detected in macrophages, monocytes, and lymphocytes in the white pulp. In the brain, it was detected in the nerve cells of the hippocampus and cerebral cortex. Analysis by gelatin zymography confirmed the presence of a latent or an active form of trypsin in various normal mouse tissues. Reverse transcription-polymerase chain reaction analysis also confirmed the expression of trypsin genes in the spleen, liver, kidney, and brain of normal mice. Such a broad distribution of trypsin suggests its general roles in the maintenance of normal epithelial cell functions, the immune defense system, and the central nervous system.

Animals↗
PubMed1998

Different effect of oxytocin on membrane potential of supraoptic oxytocin neurons in virgin female and male rats in vitro.

The effects of oxytocin on membrane potential were investigated in the supraoptic nucleus (SON) neurons of rats using whole-cell patch-clamp technique. SON neurons were electrophysiologically identified as oxytocin (OT) or vasopressin (VP) neurons. Application of OT (1 x 10[-7] M) hyperpolarized membrane potentials of OT neurons in virgin female rats but depolarized membrane potentials of putative OT neurons in male rats. The membrane conductance of SON neurons were increased by treatment of OT in both sexes, suggesting that OT increased the opening of channels on SON neurons. The reversal potential of OT neurons in virgin female rats and putative OT neurons in male rats under OT effective conditions were -66 +/- 1 mV (n = 4) and -46 +/- 2 mV (n = 5), respectively. These data suggest that OT released within the SON suppresses the activity of OT neurons in virgin female rats while it excites putative OT neurons in male rats.

Animals↗
PubMed1998

Infant cold exposure changes Fos expression to acute cold stimulation in adult hypothalamic brain regions.

It is known that cold exposure as an infant results in a permanent cold tolerance which is accompanied by a reduced rate of colonic temperature decline and increased metabolic heat production to cold stimulation. The present study was aimed to elucidate the central mechanism of cold tolerance of adult rats with cold exposure as infants. Newborn infants were exposed to cold ambient (4 degrees C) daily for 2 weeks, and when they were 15-weeks old, Fos expression to acute cold stimulation (10 degrees C) in whole brain regions was investigated using quantitative immunohistochemistry. Acute cold stimulation induced a significant increase of Fos-positive neurons in many nuclei of whole brain areas in adult rats both with and without cold exposure as infants. However, the number of Fos-positive neurons was significantly less in the rats with cold exposure than without cold exposure as infants, particularly in the hypothalamic nuclei such as the lateral septal nucleus (LS), preoptic area (POA), parvocellular paraventricular nucleus (pPVN0, ventromedial hypothalamic nucleus (VMH) and supramammillary nucleus (SuM). However, there was no significant difference in the number of Fos-positive neurons in the extra-hypothalamic regions between the rats with and without cold exposure as infants. These results suggest that the central mechanism of cold tolerance with cold exposure as infants is due to metabolic changes of the hypothalamic brain regions.

Animals↗
PubMed1998

Comparison of the expression of two immediate early gene proteins, FosB and Fos in the rat preoptic area, hypothalamus and brainstem during pregnancy, parturition and lactation.

Medial preoptic area (MPA), supraoptic nucleus (SON), magnocellular (MaPVN) and parvocellular (PaPVN) paraventricular hypothalamic nuclei, and mesencephalic lateral tegmentum (MLT) are involved in maternal behavior, parturition and lactation. This study investigated the FosB and Fos immunoreactivity in these regions of virgin, pregnant, parturient, lactating, and lactating-arrested rats. The patterns of FosB and Fos expression were compared between the sections taken from the same animals. Quantitative immunohistochemistry revealed a significant increase in the numbers of FosB-positive neurons in the MPA, SON, MaPVN, and MLT of parturient and lactating females as compared with pregnant or virgin animals. In lactating rats, the numbers of FosB-positive neurons in the MPA, PaPVN, and MLT were increased, but the numbers in the SON and MaPVN were decreased as compared with parturient females. Many Fos-positive neurons were also seen in parturient and lactating rats, and the patterns of Fos expression in each region were quite similar to those of FosB. Moreover, double-labeling immunohistochemistry revealed that: (1) many FosB-positive nuclei were observed in oxytocin and vasopressin neurons of the SON and PVN in parturient rats; (2) within FosB-positive neurons, 89.5% in the MPA, 86.8% in the MLT of parturient rats, and 92% in the MPA and 90.8% in the MLT of lactating animals were also Fos-positive. Only a small number of FosB and Fos-positive neurons were seen in females that were killed in the early stage of parturition. Removal of the litters immediately after parturition completely eliminated FosB and Fos expression in each region in the dams. Taken together, the present results suggest that FosB expression is co-involved with Fos in the neural activation during parturition and lactation in rats.

Animals↗
PubMed1998

Stimulation of cellular growth and adhesion to fibronectin and vitronectin in culture and tumorigenicity in nude mice by overexpression of trypsinogen in human gastric cancer cells.

It has previously been reported that the trypsinogen gene is expressed in various human cancers. To investigate the possible role of trypsin in tumor malignancy, trypsinogen-1 cDNA was introduced into the human gastric carcinoma cell line MKN-1. The overexpression of trypsinogen-1 in MKN-1 cells stimulated cellular growth and adhesion to fibronectin and vitronectin when the trypsinogen activator enterokinase was added into the culture. Enterokinase treatment of the conditioned medium of the MKN-1 transfectants partially converted the proforms of gelatinases B and A to their apparent active forms. When the MKN-1 transfectants expressing trypsinogen-1 were intraperitoneally transplanted into nude mice, the mice frequently produced tumors in the colon, spleen and liver. However, the mice implanted with control MKN-1 cells produced no tumors. These results strongly suggest that tumor-derived trypsin contributes to the disseminated growth of some types of cancer cells including gastric cancer.

Adenocarcinoma↗