[A case of severe respiratory failure due to varicella pneumonia].
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Acyclovir↗
Biomedical subjects
N Sugimoto
Publications and source records attributed to N Sugimoto.
Intergranular bridges in the anterior pituitary cell and their possible involvement in Ca2+-induced granule-granule fusion.
Quick-freeze deep-etch electron microscopy showed the presence of bridge-like structures between adjacent secretory granules in rat anterior pituitary secretory cells. These intergranular bridges were variable in length and thickness. The finest bridges were 7-8 nm in length, while the longest ones were as long as 80 nm. Annexin II, one of the Ca2+-dependent phospholipid-binding proteins, is known to interlink between two membranes and induce aggregation of liposomes and chromaffin granules under the presence of Ca2+. In anterior pituitary cells, annexin II was detected by immunoelectron microscopy at the contact sites of secretory granules with other granules. The anterior pituitary cells treated under the presence of extracellular Ca2+ with Clostridium perfringens enterotoxin which induces Ca2+ influx showed multigranular exocytosis, i.e., multiple fusions of secretory granules with each other and with the plasma membrane. The granule-granule fusion in progress could be captured by the quick-freeze deep-etch technique. The membranes of adjacent secretory granules were partially fused at their contact sites where intergranular strands were no longer seen, while there existed intergranular strands between unfused portions of the granule membranes. From these results, we consider that the intergranular bridges, some of which may be composed of annexin II, are involved in Ca2+-induced granule-granule fusion in anterior pituitary cells.
Animals↗
A novel missense mutation of the tissue-nonspecific alkaline phosphatase gene detected in a patient with hypophosphatasia.
Hypophosphatasia is a rare heritable inborn error of metabolism characterized by abnormal bone mineralization associated with a deficiency of alkaline phosphatase. The clinical expression of hypophosphatasia is highly variable, ranging from death in utero to pathologic fractures first presenting in adulthood. We investigated the tissue-nonspecific alkaline phosphatase (TNSALP) gene from a Japanese female patient with hypophosphatasia. By a quantitative polymerase chain reaction (PCR) method, the amount of TNSALP mRNA appeared to be almost equal to that in normal individuals. Gene analysis clarified that the hypophosphatasia originated from a missense mutation and a nucleotide deletion. The missense mutation, a C--> T transition at position 1041 of cDNA, results in an amino acid change from Leu to Phe at codon 272, which has not yet been reported. The previously reported deletion of T at 1735 causes a frame shift mutation downstream from Leu at codon 503. Family analysis showed that the mutation 1041T and the deletion 1735T had been inherited from the proband's father and mother, respectively. An expression experiment revealed that the mutation 1041T halved the expression of alkaline phosphatase activity. Using homology analysis, the Leu-272 was confirmed to be highly conserved in other mammals.
Adolescent↗
The impairment of flow-mediated vasodilatation in obese men with visceral fat accumulation.
BACKGROUND: Obesity has been reported to be associated with coronary artery disease and other atherosclerotic diseases. Recently, evidence has accumulated indicating that intra-abdominal visceral fat accumulation contributes to atherogenesis; however, the mechanism underlying this remains to be determined. This study was undertaken to elucidate whether intra-abdominal visceral fat accumulation impairs vascular endothelial function in obese men. METHODS AND RESULTS: Thirty-eight obese men (body mass index (BMI) > or = 26.0), aged 19-64 y (mean age 37.6 +/- 1.8 y) and 23 age-matched non-obese subjects were examined. According to the ratio of the maximum thickness of preperitoneal fat to the minimum thickness of subcutaneous fat (Pmax/Smin) obtained by longitudinal ultrasound scanning in the subxiphoid region in obese men, we divided obese subjects into two categories; visceral (Pmax/Smin > or = 1; n=23) and subcutaneous type (Pmax/Smin < 1; n=15). To investigate endothelial function, we performed ultrasound measurement of the brachial artery diameter non-invasively both at rest and during reactive hyperaemia in the muscle distal to the brachial artery which causes endothelium-dependent vasodilatation. The brachial diameter change was also measured after sublingual administration of nitroglycerin, which causes endothelium-independent vasodilatation. Flow-mediated diameter (D) increase (%FMD; deltaD/D x 100), in the subjects with visceral type obesity (3.09 +/- 0.43%) was significantly lower than those of the subjects with subcutaneous type obesity and non-obese subjects (7.90 +/- 0.51%, 8.91 +/- 0.44%, respectively, P < 0.01). The magnitude of endothelium-independent vasodilatation by nitroglycerin was similar in all groups. On multiple regression analysis, the Pmax/Smin showed a significant inverse correlation with %FMD. CONCLUSIONS: The subjects with visceral type obesity, rather than those with the subcutaneous type, are associated with impaired flow-mediated endothelium-dependent vasodilatation of the brachial artery.
Adipose Tissue↗
Formation of ring-shaped structures on erythrocyte membranes after treatment with botulinolysin, a thiol-activated hemolysin from Clostridium botulinum.
Damage to erythrocyte membranes by botulinolysin (BLY) was studied by electron microscopy, which revealed ring-shaped structures with inner diameters and widths of approximately 32 and 6.7 nm, respectively. BLY bound to membranes at 0 degrees C, but subsequent treatment with glutaraldehyde prevented ring formation during further incubation at 37 degrees C. Zn2+ ions inhibited ring formation but not binding of BLY to membranes.
Bacterial Toxins↗
Human herpesvirus 6 open reading frame U12 encodes a functional beta-chemokine receptor.
Human herpesvirus 6 (HHV- 6), which belongs to the betaherpesvirus subfamily and infects mainly T cells in vitro, causes acute and latent infections. HHV- 6 contains two genes (U12 and U51) that encode putative homologs of cellular G-protein-coupled receptors (GCR), while three other betaherpesviruses, human cytomegalovirus, murine cytomegalovirus, and human herpesvirus 7, have three, one, and two GCR-homologous genes, respectively. The U12 gene is expressed late in infection from a spliced mRNA. The U12 gene was cloned, and the protein was expressed in cells and analyzed for its biological characteristics. U12 functionally encoded a calcium-mobilizing receptor for beta-chemokines such as regulated upon activation, normal T expressed and secreted (RANTES), macrophage inflammatory proteins 1alpha and 1beta (MIP-1alpha and MIP-1beta) and monocyte chemoattractant protein 1 but not for the alpha-chemokine interleukin-8, suggesting that the chemokine selectivity of the U12 product was distinct from that of the known mammalian chemokine receptors. These findings suggested that the product of U12 may play an important role in the pathogenesis of HHV- 6 through transmembrane signaling by binding with beta-chemokines.
Amino Acid Sequence↗
Thermoeffector thresholds and preferred ambient temperatures of the FOK rat.
The FOK is an inbred rat strain with a genotypic adaptation to hot environments. The present study compared the thermoeffector thresholds and preferred ambient temperatures (Tpref) of the FOK rat with those of other rat strains. Male FOK, WKAH, and Donryu rats were used. First, they were loosely restrained and placed individually in a metabolic chamber with an ambient temperature of 26.0 degrees C. Their hypothalamic temperature (T(hy)), tail skin temperature (Tsk), and heat production (M) were measured. After thermal equilibrium had been attained, the rats were gradually warmed and then cooled using an intravenous thermode. The threshold T(hy) values for tail skin vasodilation and cold-induced thermogenesis were defined as the points at which sharp increases in Tsk and M occurred, respectively. The two thresholds of the FOK rat were lower than those of the WKAH and Donryu rats. In a second set of experiments, the FOK and WKAH rats were placed individually in a thermocline. Their intra-abdominal temperatures (T(ab)) were measured by a biotelemetry system, and the rats' Tpref values were estimated with the thermal gradient. Mean T(ab) and Tpref over a 24-h period for the FOK rat were significantly lower than those of the WKAH rat. The results suggest that in the FOK rat the control ranges of autonomic and behavioral thermoregulation are lower than those of the other rat strains examined. This contributes to the maintenance of core temperature at low levels.
Animals↗
Methodology of fever research: why are polyphasic fevers often thought to be biphasic?
This study explains why the recently described triphasic lipopolysaccharide (LPS) fevers have been repeatedly mistaken for biphasic fevers. Experiments were performed in loosely restrained male Wistar rats with a catheter implanted into the right jugular vein. Each animal was injected with Escherichia coli LPS, and its colonic (Tc) and tail skin temperatures were monitored. The results are presented as time graphs and phase-plane plots; in the latter case the rate of change of Tc is plotted against Tc. At an ambient temperature (Ta) of 30.0 degrees C, the response to the 10 microg/kg dose of LPS was triphasic, as is obvious from time graphs of Tc (3 peaks), time graphs of effector activity (3 waves of tail skin vasoconstriction), and phase-plane plots (3 complete loops). When the Ta was below neutral (22.0 degrees C) or the LPS dose was higher (100 or 1,000 microg/kg), the time graph of Tc did not allow for the reliable detection of all three febrile phases, but the phase-plane plot and time graph of effector activity clearly revealed the triphasic pattern. In a separate experiment, LPS (10 microg/kg) or saline was injected via one of two different procedures: in the first group the injection was performed through the jugular catheter, from outside the experimental chamber; in the second group the same nonstressing injection was combined with opening the chamber and pricking the animal in its lower abdomen with a needle. In the first group the febrile response was obviously triphasic, and none of the phases was due to the procedure of injection per se (injection of saline did not affect Tc). In the second group the fever similarly consisted of three Tc rises, but it might have been readily mistaken for biphasic because the first rise was indistinguishable from stress hyperthermia occurring in the saline-injected (and needle-pricked) controls. We conclude that several methodological factors (dose of LPS, procedure of its injection, and Ta) have contributed, although each in a different way, to the common misbelief that there are only two febrile phases.
Activity Cycles↗
Signaling the brain in systemic inflammation: which vagal branch is involved in fever genesis?
Recent evidence has suggested a role of abdominal vagal afferents in the pathogenesis of the febrile response. The abdominal vagus consists of five main branches (viz., the anterior and posterior celiac branches, anterior and posterior gastric branches, and hepatic branch). The branch responsible for transducing a pyrogenic signal from the periphery to the brain has not as yet been identified. In the present study, we address this issue by testing the febrile responsiveness of male Wistar rats subjected to one of four selective vagotomies: celiac (CBV), gastric (GBV), hepatic (HBV), or sham (SV). In the case of CBV, GBV, and HBV, only the particular vagal branch(es) was cut; for SV, all branches were left intact. After the postsurgical recovery (26-29 days), the rats had a catheter implanted into the jugular vein. On days 29-32, their colonic temperature (Tc) responses to a low dose (1 microg/kg) of Escherichia coli lipopolysaccharide (LPS) were studied. Three days later, the animals were subjected to a 24-h food and water deprivation, and the effectiveness of the four vagotomies to induce gastric food retention, pancreatic hypertrophy, and impairment of the portorenal osmotic reflex was assessed by weighing the stomach and pancreas and measuring the specific gravity of bladder urine, respectively. Stomach mass, pancreas mass, and urine density successfully separated the four experimental groups into four distinct clusters, thus confirming that each type of vagotomy had a different effect on the indexes measured. The Tc responses of SV, CBV, and GBV rats to LPS did not differ and were characterized by a latency of approximately 40 min and a maximal rise of 0.7 +/- 0.1, 0.6 +/- 0.1, and 0.9 +/- 0.2 degrees C, respectively. The fever response of the HBV rats was different; practically no Tc rise occurred (0.1 +/- 0.2 degrees C). The HBV appeared to be the only selective abdominal vagotomy affecting the febrile responsiveness. We conclude, therefore, that the hepatic vagus plays an important role in the transduction of a pyrogenic signal from the periphery to the brain.
Animals↗
Pasteurella multocida toxin and Bordetella bronchiseptica dermonecrotizing toxin elicit similar effects on cultured cells by different mechanisms.
We compared the effects of Pasteurella multocida toxin (PMT) with Bordetella bronchiseptica dermonecrotizing toxin (DNT) at a cellular level under same conditions. Both PMT and DNT cause actin stress fiber formation in MC3T3-E1 cells which is known to be regulated by the small GTP-binding protein Rho. DNT induced mobility shifts of Rho on SDS-polyacrylamide gel electrophoresis, indicating direct modification as reported elsewhere. In contrast, no alternations in the electrophoretic mobility of Rho were found in lysates from PMT-treated cells. PMT but not DNT increased the intracellular level of inositol phosphates, indicating the elevation of phospholipase C (PLC) activity in the PMT-treated cells. These results indicate that PMT does not have Rho as a target but activates PLC. The formation of actin stress fiber by PMT seems to be stimulated through the indirect activation of Rho, which resides downstream of PLC, PMT and DNT seem to elicit similar toxic effects, at least in part, through the activation of Rho.
3T3 Cells↗
Changes in core temperature and thermoeffector thresholds in exercise-trained rats.
Spontaneous running in a running wheel has emerged as an alternative method of exercise in small animals. The present study investigated how exercise training with a running wheel affects core temperature level and thermoeffector thresholds in rats. Female rats were allowed to run freely in the wheel for 6 months. Sedentary controls did not exercise during the same period. After the exercise training period, they were loosely restrained and their threshold core temperatures for tail skin vasodilation and cold-induced thermogenesis were determined by warming or cooling the animals by use of a chronically implanted intravenous thermode. Resting and threshold core temperatures of the exercise-trained rats were higher than those of the sedentary controls. The results suggest that in rat, exercise training with a running wheel shifts threshold temperatures for heat loss and heat production to high levels, which may result in a rise in core temperature level.
Animals↗
[Neutrophil-endothelial cell interactions in gastrointestinal diseases].
The adherence of neutrophils to the endothelium is a crucial early event in the inflammatory and immunological reaction. Neutrophil-endothelial cell interactions are known to be mediated by adhesion molecules that are expressed on each cell. Among the adhesion molecules expressed on leukocytes, the CD11/CD18 integrin family plays a major role in the adhesion and transendothelial migration of neutrophils. The two most extensively characterized endothelial cell adhesion molecules are intercellular adhesion molecule-1 and E-selectin. These adhesion molecules are involved in the pathogenesis of several digestive diseases such as Helicobacter pylori, non steroidal anti inflammatory drug- or stress-induced gastric mucosal injury, inflammatory bowel diseases.
Anti-Inflammatory Agents, Non-Steroidal↗
Clostridium perfringens enterotoxin utilizes two structurally related membrane proteins as functional receptors in vivo.
Human and mouse cDNAs showing homology to the Clostridium perfringens enterotoxin (CPE) receptor gene (CPE-R) from Vero cells (DDBJ/EMBL/GenBankTM accession no. D88492) (Katahira, J., Inoue, N., Horiguchi, Y., Matsuda, M., and Sugimoto, N. (1997) J. Cell Biol. 136, 1239-1247) were cloned. They were classified into two groups, the Vero cell CPE receptor homologues and rat androgen withdrawal apoptosis protein (RVP1; accession no. M74067) homologues, based on the similarities of primary amino acid sequences. L929 cells that were originally insensitive to CPE became sensitive to CPE on their transfection with cDNAs encoding either the CPE receptor or RVP1 homologues, indicating that these gene products are not only structurally similar but also functionally active as receptors for CPE. By binding assay, the human RVP1 homologue showed differences in affinity and capacity of binding from those of the human CPE receptor. Northern blot analysis showed that mouse homologues of the CPE receptor and RVP1 are expressed abundantly in mouse small intestine. The expression of CPE-R mRNA in the small intestine was restricted to cryptic enterocytes, indicating that the CPE receptor is expressed in intestinal epithelial cells. These results are consistent with reports that CPE binds to the small intestinal cells via two different kinds of receptors. High levels of expression of CPE-R and/or RVP1 mRNA were also detected in other organs, including the lungs, liver, and kidneys, but only low levels were expressed in heart and skeletal muscles. These results indicate that CPE uses structurally related cellular proteins as functional receptors in vivo and that organs that have not so far been recognized as CPE-sensitive have the potential to be targets of CPE.
Amino Acid Sequence↗
Bordetella bronchiseptica dermonecrotizing toxin induces reorganization of actin stress fibers through deamidation of Gln-63 of the GTP-binding protein Rho.
Bordetella dermonecrotizing toxin causes assembly of actin stress fibers and focal adhesions in some cultured cells and induces mobility shifts of the small GTP-binding protein Rho on electrophoresis. We attempted to clarify the molecular basis of the toxin action on Rho. Analysis of the amino acid sequence of toxin-treated RhoA revealed the deamidation of Gln-63 to Glu. The substitution of Glu for Gln-63 of RhoA by site-directed mutagenesis caused a mobility shift on electrophoresis, which was indistinguishable from that of the toxin-treated RhoA. Neither mutant RhoA-bearing Glu-63 nor toxin-treated RhoA significantly differed from untreated wild type RhoA in guanosine 5'-[gamma-thio]triphosphate binding activity but both showed a 10-fold reduction in GTP hydrolysis activity relative to untreated RhoA. C3H10T1/2 cells transfected with cDNA of the mutant RhoA bearing Glu-63 showed extensive formation of actin stress fibers similar to the toxin-treated cells. These results indicate that the toxin catalyzes deamidation of Gln-63 of Rho and renders it constitutively active, leading to formation of actin stress fibers.
Actins↗
Role of Nd3+ and Pb2+ on the RNA cleavage reaction by a small ribozyme.
Leadzyme is a ribozyme that requires Pb2+. We have previously shown that the addition of Nd3+ in the presence of Pb2+ increased significantly the yield of the RNA cleavage reaction by a leadzyme, although other rare earth ions or divalent ions except Pb2+ did not promote the reaction [Sugimoto, N., & Ohmichi, T. (1996) FEBS Lett. 393, 97-100]. To investigate the combined effects of Nd3+ and Pb2+ on the binding and cleavage steps of a leadzyme, CUGGGAGUCC, with a substrate, GGACCGAGCCAG, kinetics for the leadzyme reaction have been measured at various concentration ratios of Nd3+ and Pb2+. At low concentration ratios of Nd3+ under a constant total concentration of metal ions, Nd3+ increased the stability of the complex between the leadzyme and the substrate. In contrast, at high concentration ratios of Nd3+, the addition of Nd3+ decreased the stability of the complex. The rate constant of the cleavage step was maximized when the ratio of Nd3+ to Pb2+ was 1:1. These results suggest that the complex between the leadzyme and the substrate has binding sites for Nd3+ ion that influence complex stability and catalyze directly the cleavage reaction. On the basis of the results, we propose a two-metal-ion mechanism in which Pb2+ and Nd3+ play the roles of base and acid catalyst, respectively.
Binding Sites↗
Molecular cloning and functional characterization of the receptor for Clostridium perfringens enterotoxin.
A cDNA encoding the Clostridium perfringens enterotoxin receptor gene (CPE-R) was cloned from an expression library of enterotoxin-sensitive Vero cells. The nucleotide sequence of CPE-R showed that the enterotoxin receptor consists of 209 amino acids with a calculated molecular mass of 22,029 D. This receptor is highly hydrophobic, contains four putative transmembrane segments, and has significant similarity to the rat androgen withdrawal apoptosis protein RVP1 and the mouse oligodendrocyte specific protein, the functions of which are unknown. The expression of CPE-R was detected in the enterotoxin-sensitive Vero, Hep3B, and Intestine 407 cell lines, but not in the enterotoxin-insensitive K562 and JY cell lines. The CPE-R gene product expressed in enterotoxin-resistant L929 cells bound to enterotoxin specifically and directly and with high affinity and rendered the cells sensitive to the toxin, indicating that the cloned receptor is functional. Results showed that enterotoxin could not assemble into a complex with a defined structure unless it interacted with the receptor. From these results, it is proposed that the enterotoxin receptor is required for both target cell recognition and pore formation in the cell membrane.
Amino Acid Sequence↗
Heat loss responses to acute heat loads in the FOK rat.
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Animals↗
Preferred ambient temperature and threshold temperatures for thermoregulation in the FOK rat.
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Animals↗