Biomedical subjects

K Nagashima

Publications and source records attributed to K Nagashima.

At least 127 records · Page 7Linked to original sources

PubMed1999

Loss of A-type lamin expression compromises nuclear envelope integrity leading to muscular dystrophy.

The nuclear lamina is a protein meshwork lining the nucleoplasmic face of the inner nuclear membrane and represents an important determinant of interphase nuclear architecture. Its major components are the A- and B-type lamins. Whereas B-type lamins are found in all mammalian cells, A-type lamin expression is developmentally regulated. In the mouse, A-type lamins do not appear until midway through embryonic development, suggesting that these proteins may be involved in the regulation of terminal differentiation. Here we show that mice lacking A-type lamins develop to term with no overt abnormalities. However, their postnatal growth is severely retarded and is characterized by the appearance of muscular dystrophy. This phenotype is associated with ultrastructural perturbations to the nuclear envelope. These include the mislocalization of emerin, an inner nuclear membrane protein, defects in which are implicated in Emery-Dreifuss muscular dystrophy (EDMD), one of the three major X-linked dystrophies. Mice lacking the A-type lamins exhibit tissue-specific alterations to their nuclear envelope integrity and emerin distribution. In skeletal and cardiac muscles, this is manifest as a dystrophic condition related to EDMD.

Animals↗

PubMed1999

Non-adherent cell-specific expression of DOCK2, a member of the human CDM-family proteins.

Human DOCK180, which was originally identified as a major protein bound to the Crk oncogene product, is an archetype of the CDM family of proteins, including Ced-5 of Caenorhabditis elegans and Mbc of Drosophila melanogaster. After DOCK180, at least three putative human proteins that manifest high amino acid sequence similarity to DOCK180 have been registered in the GenBank/EMBL database. We have designated one of them, KIAA0209, as DOCK2 and characterize here. DOCK2 mRNA was expressed mostly in peripheral blood cells, followed by slight expression in the spleen and thymus, whereas DOCK180 was expressed in all tissues tested except in peripheral blood cells. Immunostaining of human cadaver tissues revealed that the expression of DOCK2 was limited to the lymphocytes and macrophages of various organs. DOCK2 bound to and activated Rac1, as did DOCK180; however, DOCK2 did not bind to CrkII, which transduces signals at focal adhesions. Thus, DOCK180 and DOCK2 are regulators of Rac and function in adherent and non-adherent cells, respectively.

Amino Acid Sequence↗

PubMed1999

Proton Adsorption onto Alumina: Extension of Multisite Complexation (MUSIC) Theory.

The adsorption isotherm of protons onto a commercial gamma-alumina sample was determined in aqueous nitric acid with sodium nitrate as a background electrolyte. Three discrete regions could be discerned in the log-log plots of the proton isotherm determined at the solution pH 5 to 2. The multisite complexation (MUSIC) model was modified to analyze the simultaneous adsorption of protons onto various kinds of surface species. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

PKA-mediated phosphorylation of the human K(ATP) channel: separate roles of Kir6.2 and SUR1 subunit phosphorylation.

ATP-sensitive potassium (K(ATP)) channels play important roles in many cellular functions such as hormone secretion and excitability of muscles and neurons. Classical ATP-sensitive potassium (K(ATP)) channels are heteromultimeric membrane proteins comprising the pore-forming Kir6.2 subunits and the sulfonylurea receptor subunits (SUR1 or SUR2). The molecular mechanism by which hormones and neurotransmitters modulate K(ATP) channels via protein kinase A (PKA) is poorly understood. We mutated the PKA consensus sequences of the human SUR1 and Kir6.2 subunits and tested their phosphorylation capacities in Xenopus oocyte homogenates and in intact cells. We identified the sites responsible for PKA phosphorylation in the C-terminus of Kir6.2 (S372) and SUR1 (S1571). Kir6.2 can be phosphorylated at its PKA phosphorylation site in intact cells after G-protein (Gs)-coupled receptor or direct PKA stimulation. While the phosphorylation of Kir6.2 increases channel activity, the phosphorylation of SUR1 contributes to the basal channel properties by decreasing burst duration, interburst interval and open probability, and also increasing the number of functional channels at the cell surface. Moreover, the effect of PKA could be mimicked by introducing negative charges in the PKA phosphorylation sites. These data demonstrate direct phosphorylation by PKA of the K(ATP) channel, and may explain the mechanism by which Gs-coupled receptors stimulate channel activity. Importantly, they also describe a model of heteromultimeric ion channels in which there are functionally distinct roles of the phosphorylation of the different subunits.

ATP-Binding Cassette Transporters↗

PubMed1999

Activation of the ERK/MAPK pathway by an isoform of rap1GAP associated with G alpha(i)

Many receptors for neuropeptides and hormones are coupled with the heterotrimeric G(i) protein, which activates the p42/44 mitogen-activated protein kinase (ERK/MAPK) cascade through both the alpha- and betagamma-subunits of G(i). The betagamma-subunit activates the ERK/MAPK cascade through tyrosine kinase. Constitutively active G(alpha)i2 (gip2) isolated from adrenal and ovarian tumours transforms Rat-1 fibroblasts and also activates the ERK/MAPK cascade by an unknown mechanism. The ERK/MAPK pathway is activated by Ras, and is inhibited when the low-molecular-mass GTP-binding protein Rap1 antagonizes Ras function. Here we show that a novel isoform of Rapl GTPase-activating protein, called rap1GAPII, binds specifically to the alpha-subunits of the G(i) family of heterotrimeric G-proteins. Stimulation of the G(i)-coupled m2-muscarinic receptor translocates rap1GAPII from the cytosol to the membrane and decreases the amount of GTP-bound Rap1. This decrease in GTP-bound Rap1 activates ERK/MAPK. Thus, the alpha-subunit of G(i) activates the Ras-ERK/MAPK mitogenic pathway by membrane recruitment of rap1GAPII and reduction of GTP-bound Rap1.

3T3 Cells↗

PubMed1999

Adsorption of Sodium n-Decylbenzenesulfonate onto Alumina: Relationships between Macro- and Microscopic Behavior.

The adsorption of isomer-free sodium n-decylbenzenesulfonate-d4 onto a commercial gamma-alumina sample was investigated in an aqueous solution. The prototype anionic surfactant and positively charged mineral oxide gave a characteristic sinusoidal adsorption isotherm with four discrete regions in the log equilibrium concentration-log adsorption amount plots. Deuterium NMR was applied to probe the molecular motion of the deuterated surfactant adsorbed on the surface. The results were not consistent with either the reverse orientation model or the bilayer model. An intermediate model between the two models was thus proposed for describing a partial occupation of the outer layer of the surfactant aggregates formed in a low concentration range. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Pertussis toxin-sensitive signal controls the trafficking of thymocytes across the corticomedullary junction in the thymus.

We investigated a role of chemokines in thymocyte trafficking. Genes encoding stromal cell-derived factor-1 and its receptor CXCR4 were detected in the cortex by in situ hybridization. Early immigrant cells did not express CXCR4, whereas their descendant CD44+CD25+CD4-CD8- cells did. CXCR4 expression was down-modulated when CD4+CD8+ double-positive cells became CD4+CD8- or CD4-CD8+ single-positive (SP) cells. Positively selected CD69+CD3intermediate cells gained CCR4, of which ligand, thymus activation-regulated chemokine, was expressed in the medulla. At the next developmental stage, CD69-CD3high cells lost CCR4 but gained CCR7. These results suggest that thymocytes use different chemokines along with their development. Blockade of chemokine receptor-mediated signaling by pertussis toxin perturbed the normal distribution of SP cells and resulted in the accumulation of SP cells in the cortex. Thus, a pertussis toxin-sensitive event controls the trafficking of SP cells across the corticomedullary junction.

Animals↗

PubMed1999

Analysis of human lymphotropic T-cell virus type II-like particle production by recombinant baculovirus-infected insect cells.

The molecular processes involved in retrovirus assembly and budding formation remain poorly understood. The gag-pro-pol genes of human lymphotropic T-cell virus type II (HTLV-II) are translated into Gag, Gag-Pro, or Gag-Pro-Pol by frameshift events. In the present study, we investigated the roles of the gag, pro, and pol regions of HTLV-II in viral particle formation using recombinant baculoviruses. In this study we could successfully produce mature HTLV-II viral particles containing core structures using a construct expressing the entire gag-pro-pol region. We also investigated the role of the pol region in particle formation. Deletion of the pol region affects viral particle assembly or release very little, indicating that the gag-pro region is sufficient for viral particle formation and maturation. Expression of the Gag proteins alone or Gag proteins with inactivated viral proteases (Pro) resulted in the formation of viral particles; however, these particles did not contain core structures. These results suggest the intracellular expression of Gag with Pro of HTLV-II is essential for the production of mature virus particles, whereas that of Pol is not.

Animals↗

PubMed1999

Wernicke encephalopathy-like symptoms as an early manifestation of Creutzfeldt-Jakob disease in a chronic alcoholic.

A case of Creutzfeldt-Jakob disease (CJD) with presenting Wernicke encephalopathy (WE)-like symptoms and severe insomnia is presented. An 80-year-old alcoholic man with a 6 month history of tremors, ataxia, memory loss and confabulation, developed profound insomnia, confusion, and delirium with vivid hallucinations. Polysomnography revealed a marked reduction of sleep time, with central-type sleep apnea. Neither myoclonus nor periodic synchronous discharge (PSD) was observed. An autopsy revealed diffuse spongiform changes and astrocytosis throughout the cerebral gray matter, with severe involvement of the mammillary bodies and thalamus. Prion protein (PrP) immunostaining was positive in kuru plaques in the cerebellum, PrP polymorphism at codon 129 was heterozygous Met/Val, and proteinase K resistant PrP (PrP(res)) was demonstrated by Western blotting. The lack of necrotizing lesions in the mammillary bodies, thalamus, and periaqueductal gray matter could rule out WE. The data suggest that the present case of CJD is consistent with PrP(res) type 2 (CJD M/V 2), but was unique in the lack of some typical CJD signs and the presence of signs of WE and sleep abnormalities.

Aged↗

PubMed1999

Augmented expression of macrophage migration inhibitory factor (MIF) in the telencephalon of the developing rat brain.

Macrophage migration inhibitory factor (MIF) has been characterized as a proinflammatory cytokine, hormone, and immunomodulator. We previously demonstrated the distribution of MIF in the adult rat brain and revealed its expression in neurons as well as glial cells. In this study, we investigated the localization of MIF in the developing rat brain from embryonic day (ED) 13 to ED19, and after birth from postnatal day (PD) 1 to PD28 using both immunohistochemistry and in situ hybridization. On ED16, the signals of MIF mRNA were high in the ventricular, subventricular, and intermediate zones of the telencephalon, in which 'neuropoietic' progenitor cells proliferate and migrate from the ventricular zone to the superficial layer in the cerebral cortex. The mRNA expression was detected throughout the postnatal period, and intense signals of the transcript were seen in the ventricle and in layers I, II and III of the cerebral cortex at PD5. Similarly, positive staining of MIF protein was seen in the ventricular zone by immunohistochemical analysis, although the positively stained area appeared to be smaller than the mRNA expression. Taken together, these results suggest that the increase in MIF mRNA in the developing brain reflects the growth and maturation of neurons and glial cells.

Animals↗

PubMed1999

Transitional-cell carcinoma of the bladder in an adolescent.

We report a rare case of transitional-cell carcinoma of the bladder in an 18-year-old girl with intermittent hematuria. The tumor was diagnosed through the cystogram phase of the excretory urogram and bladder ultrasound. Transurethral resection (TUR) of the tumor was performed. As most tumors are low-grade and low-stage and are associated with an excellent prognosis, endoscopic TUR is the preferred therapeutic measure. However, recurrence as well as death have been reported in this age group. These patients should be followed carefully, similar to adult patients.

Adolescent↗

PubMed1999

Adult Leigh syndrome with mitochondrial DNA mutation at 8993.

Adult onset Leigh syndrome with a nucleotide (nt) 8993 mutation in mitochondrial (mt) DNA is reported. A 43-year-old woman with a 6-year-history of insulin-resistant diabetes mellitus developed muscular weakness, intractable nausea and vomiting, and anemia. These were followed vertigo, blindness, and deafness with nystagmus. Magnetic resonance imaging (MRI) revealed abnormal high intensities in the bilateral medial regions of the thalamus and periaqueductal gray matters. Autopsy disclosed well-demarcated necrotizing lesions with prominent capillaries in the areas detected by MRI, which were sufficiently diagnostic for Leigh syndrome. MtDNA analysis performed on DNAs extracted from formalin-fixed tissues including liver, heart, brain, muscle, kidney and pancreas showed a T-->G mutation at nt 8993. This is the first case of adult Leigh syndrome demonstrating on mtDNA mutations.

Adult↗

PubMed1999

Allelic variations of the D2 dopamine receptor gene in children with idiopathic short stature.

The D2 dopamine receptor (DRD2) plays a major role in growth hormone (GH) secretion. Recent reports indicate that Taq I A DRD2 gene alleles (A1 and A2) are related to the function of DRD2. Idiopathic short stature (ISS) is defined as short stature without accompanying malnutrition, chronic disease, and endocrinological disorders. However, some reports suggest that ISS is associated with a mild disturbance of GH secretion. In this study, we examined the notion that allelic variants of the DRD2 are associated with ISS. We studied 55 children with ISS aged 8.4 (SD 2.9) years; (group I) and 104 age-matched children of normal stature (group II). Informed consent was obtained from each child's parent or guardian. Genomic DNAs were extracted from peripheral mononuclear cells and amplified by polymerase chain reaction (PCR). The PCR products were digested by Taq1 and resolved by electrophoresis. The frequency of the A1 allel was significantly higher in group I (0.42) than in group II (0.26). The insulin-like growth factor (IGF)-I ratio (the ratio of the individual level to the normal mean value according to age at our laboratory center) was significantly lower in group I than in group II. When group I was subdivided into group A (with the A1 allele) and group B (with only the A2 allele), group A had a significantly lower peak GH response to the l-dopa test, lower levels of IGF-I, and retarded bone maturation. These findings indicate that polymorphism of the DRD2 gene may be one genetic factor that affects body height in childhood, acting through the hypothalamus (GH-releasing hormone)--pituitary (GH)--IGF-I axis.

Alleles↗

PubMed1999

Neuroprotective effects of a dihydropyridine derivative, 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarbox ylic acid methyl 6-(5-phenyl-3-pyrazolyloxy)hexyl ester (CV-159), on rat ischemic brain injury.

CV-159, 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylic++ + acid methyl 6-(5-phenyl-3-pyrazolyloxy)hexyl ester, is a dihydropyridine derivative that blocks the L-type Ca2+ channel and inhibits the calmodulin (CaM)-dependent pathway. In this study, we examined the effects of CV-159 on rat ischemic brain injury. CV-159 (5 and 10 mg/kg, p.o.) gave significant protection against delayed neuronal death in the hippocampal CA1 region after 15-min transient forebrain ischemia. In contrast, the Ca2+ antagonists nicardipine (1 and 10 mg/kg, p.o.) and nifedipine (1 mg/kg, i.p.) and the CaM antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7, 500 ng, i.c.v.) had no effect on this hippocampal neuronal death. CV-159 also diminished the size of the brain infarct after permanent middle cerebral artery (MCA) occlusion, although physiological variables, including regional cerebral blood flow, were not affected. The increase in the water content of the infarcted cortex induced by MCA occlusion was significantly reduced by CV-159. On the other hand, neither nicardipine nor nifedipine affected the brain infarct size, volume or increased water content induced by MCA occlusion, as previously reported (A. Sauter and M. Rudin, Am. J. Hypertens. 4 121S-127S, 1991). These findings indicate that Ca2+ antagonists, such as nicardipine and nifedipine, and W-7 have no effect on rat ischemic brain injury. The results suggest that CV-159 protects against ischemic brain injury. This might be mediated by both blocking the L-type Ca2+ channel and inhibiting CaM-dependent function via Ca2+/CaM binding at a different binding site from that of W-7 to CaM (H. Umekawa, K. Yamakawa, K. Nunoki, N. Taira, T. Tanaka, and H. Hidaka, Biochem. Pharmacol. 37 3377-3381, 1988).

Animals↗

PubMed1999

Glial cell line-derived neurotrophic factor protects against delayed neuronal death after transient forebrain ischemia in rats.

Glial cell line-derived neurotrophic factor, a member of the transforming growth factor-beta superfamily, is a potent neurotrophic factor, which has a variety of biological activities that affect several types of neurons in both the central and peripheral nervous systems. In this study, we examined the effects of glial cell line-derived neurotrophic factor on delayed neuronal death in the hippocampal CA1 region of rats after transient forebrain ischemia. In the control rats pretreated with the vehicle, transient forebrain ischemia-induced delayed neuronal death in the hippocampal CA1 region was observed seven days after reperfusion. Pretreatment with glial cell line-derived neurotrophic factor (1.0 microg), which was directly microinjected into the right hippocampal CA1 region, gave significant protection against the delayed hippocampal neuronal death. On the contralateral side of the hippocampus, which was not injected with glial cell line-derived neurotrophic factor, delayed neuronal death similar to that seen in vehicle-treated control animals was observed. Intracerebroventricular glial cell line-derived neurotrophic factor (2.5 microg) injection also protected against delayed neuronal death. In addition, pretreatment with glial cell line-derived neurotrophic factor gave significant protection against apoptotic cell death induced by brain ischemia in the hippocampal CA1 region, as determined by in situ staining for DNA fragmentation. These findings suggest that glial cell line-derived neurotrophic factor plays an important role in delayed neuronal death induced by brain ischemia.

Animals↗

PubMed1999

A method for detection of a cytokine and its mRNA in the central nervous system of the developing rat.

We report here an effective and concise method to determine the localization of macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, and its mRNA in the central nervous system of pre- and postnatal rats. This method allows for double staining to demonstrate localization of different molecules on the same tissue specimen at the levels of mRNA and proteins by in situ hybridization and immunohistochemistry, respectively. Additionally, the present method gives results more quickly than the conventional isotopic techniques. By use of this method, we carried out immunohistochemistry with an anti-rat MIF polyclonal antibody and demonstrated positive staining using the avidin-biotin complex method (ABC method). To detect its mRNA, we performed nonradioactive in situ hybridization using a digoxigenin (DIG)-labeled RNA probe prepared from a full length fragment of rat MIF cDNA. MIF was strongly expressed in the telencephalon on embryonic day 16. Non-radioactive in situ hybridization with a DIG-labeled RNA probe as well as the immunohistochemistry described here could be applicable to characterize localization of mRNA and proteins of different molecules on the same tissue specimen.

Animals↗

PubMed1999

Dysplastic gangliocytoma (Lhermitte-Duclos disease) associated with Cowden disease: report of a case and review of the literature for the genetic relationship between the two diseases.

We report a case of dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease, LDD). The patient also had cutaneous and mucosal hamartomas, adenomatous goiter, bilateral breast tumors, and gastrointestinal polyposis, indicating the diagnosis of Cowden disease (CD), the familial hamartoma syndrome. This was a rare sporadic case without any family history of CD, though CD is considered to be an autosomal dominant hereditary disease. Based on a thorough review of the previously reported cases, it is reasonable to consider that CD is inherited in autosomal dominant fashion through a CD gene (PTEN) containing a germline mutation, and that the occurrence of LDD is predicted on an additional somatic hit on the remaining normal CD allele or another unknown gene.

Adult↗

PubMed1999

An automatic monitor of formaldehyde in air by a monitoring tape method.

An automatic monitor has been developed for measuring formaldehyde in air using a sensitive tape for formaldehyde. It is based on the color change of the tape on reaction with formaldehyde. The porous cellulose tape, containing silica gel as an absorbent and impregnated with the processing solution containing hydroxylamine sulfate, Methyl Yellow (pH indicator; pH 2.9-4.0, red-yellow), glycerin and methanol, was found to be a highly sensitive means of detecting formaldehyde and maintains a stable sensitivity. When the tape was exposed to a sample of air containing formaldehyde, the color of the tape changed from yellow to red. The degree of color change was proportional to the concentration of formaldehyde at a constant sampling time and flow rate, and it could be recorded by measuring the intensity of reflected light (555 nm). The tape could be used to detect down to 0.08 ppm (World Health Organization standard) of formaldehyde with a sampling time of 30 min and a flow rate of 100 mL min-1. Reproducibility tests showed that the relative standard deviation of response (n = 10) was 3.8% for 0.1 ppm formaldehyde. The monitor is simple, specific, capable of unattended operation and is recommended for both laboratory and field operation.

Air Pollution, Indoor↗