Bezafibrate improves bacterial lipopolysaccharide-induced dyslipidemia and anorexia in rats

Bacterial endotoxin/lipopolysaccharide (LPS)-induced cachexia is characterized by weight loss, anorexia, and a disturbance in lipid metabolism, namely, hypertriacylglycerolemia. The aim of this study in rats with acute endotoxicity induced by an injection of LPS was to investigate whether bezafibrate, a ligand for peroxisome proliferator-activated receptor alpha and a lipoprotein lipase (LPL) activator, improved cachectic conditions, including impaired lipid metabolism. Short-term administration of LPS in the rats resulted in impairment of triacylglycerol clearance in plasma after the intake of fresh cream. In addition, LPS increased whole-body energy expenditure, reduced fasting body weight and caused anorexia in the rats. Bezafibrate treatment resulted in significant improvements in LPS-induced dyslipidemia and anorexia, but had no effect on energy expenditure, respiratory quotient, or fasting body weight in the endotoxic rats. Administration of LPS was also associated with a decrease in the level of messenger RNA (mRNA) expression for LPL in white adipose tissue and skeletal muscle and an increase in the mRNA levels for uncoupling protein 3 in skeletal muscle. Bezafibrate treatment reversed the decline in LPL mRNA levels in white adipose tissue but not in the skeletal muscle tissue of the rats. The enhanced uncoupling protein 3 mRNA level in the endotoxic rats was not affected by bezafibrate treatment. Plasma concentration of leptin was increased by short-term LPS treatment. Bezafibrate decreased the level of plasma leptin significantly without affecting the level of leptin mRNA expression. These results suggest that bezafibrate may be an effective drug not only for impaired triacylglycerol metabolism, but also for anorexia in cachectic states induced by bacterial infections.

Modulation of pathogenicity with norepinephrine related to the type III secretion system of Vibrio parahaemolyticus

BACKGROUND

Norepinephrine (NE) controls the functions of the gastrointestinal tract, but its role in the pathogenicity of enteropathogens is not clear. We examined the effect of NE on the pathogenicity of Vibrio parahaemolyticus with regard to its type III secretion systems (TTSSs).

METHODS

To evaluate the effect of NE on pathogenicity of V. parahaemolyticus, we examined the cytotoxic activity to Caco-2 cells and enterotoxicity by use of the rat ileal loop model. It has been reported that TTSS1 causes cytotoxicity and that TTSS2 causes enterotoxicity in the animal ileal loop model.

RESULTS

Our results showed that, although NE alone did not affect the viability of Caco-2 cells, NE stimulated the cytotoxic activity of V. parahaemolyticus. Furthermore, NE increased the transcription of the TTSS1-related genes vscQ and vscU. These results indicate that NE regulates V. parahaemolyticus cytotoxic activity. The enterotoxicity of V. parahaemolyticus was increased by NE through interaction with alpha (1)-adrenergic receptors. These results indicate that alpha (1)-adrenergic receptors on the intestinal epithelium appear to interact with V. parahaemolyticus enterotoxicity.

CONCLUSIONS

The present findings suggest that enteric NE may modulate V. parahaemolyticus pathogenicity.

APS-mediated ubiquitination of the insulin receptor enhances its internalization, but does not induce its degradation

APS, a tyrosine kinase adaptor protein with pleckstrin homology and Src homology 2 domains, is rapidly and strongly tyrosine-phosphorylated by insulin receptor kinase upon insulin stimulation. We have previously shown that APS knockout mice have increased insulin sensitivity, and that this enhancement is possibly due to increased insulin-response on adipose tissues. However, the function of APS in insulin signaling has so far been controversial. Here, we report that APS enhanced ligand-dependent multi-ubiquitination of the insulin receptor (IR) in CHO cells overexpressing the IR. APS-mediated ubiquitination of the IR induced enhancement of the IR internalization, but did not affect the IR degradation. This finding shows one of the pleiotropic functions of APS in insulin signaling.

NO-1886, a lipoprotein lipase activator, attenuates vascular smooth muscle contraction in rat aorta

The chemical compound [4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester (NO-1886) is a lipoprotein lipase activator having beneficial effects on both diabetes control and the cardiovascular system. Preventing accumulation of lipids in the cell wall, in addition to improving insulin actions on vasculature, may indirectly contribute to the reducing effect of NO-1886 on vascular resistance. However, the direct effect of NO-1886 on vascular resistance, i.e., whether NO-1886 directly modulates the function of vascular endothelium and/or smooth muscle cells has not been investigated. In this study we therefore investigated the direct effect of NO-1886 on vascular contractility using rat aortic rings and cultured smooth muscle cell-line A10. The results show that administration of NO-1886 attenuated aortic contraction induced by phenylephrine and/or a high K(+) environment, in both the presence and absence of aortic endothelium. 1-(5-Chloronaphthalene-1-sulfonyl)homopiperazine hydrochloride (ML-9), a myosin light chain kinase (MLCK) inhibitor, blocked this inhibitory effect of NO-1886, whereas inhibitors of other signaling molecules such as calmodulin, protein kinase C and Rho-kinase had no effect. The vasorelaxant effect of NO-1886 was blocked in the absence of extracellular Ca(2+), or in the presence of the Ca(2+) channel inhibitor, verapamil. NO-1886 attenuated smooth muscle contraction induced by the cumulative addition of CaCl(2). In A10 cells, NO-1886 inhibited the membrane depolarization-induced initial peak of [Ca(2+)](i) in the presence of extracellular Ca(2+). This inhibition did not occur in the absence of extracellular Ca(2+). Taken together these results demonstrate that NO-1886 attenuates smooth muscle contraction and causes vasorelaxation by an extracellular Ca(2+)- and MLCK-dependent mechanism.

Monoamine oxidase A activity and norepinephrine level in hippocampus determine hyperwheel running in SPORTS rats

An understanding of neurological mechanisms for wheel running by rodents, especially with high exercise activity, would be applicable to a strategy for promotion of exercise motivation in humans. One of several brain regions that are candidates for the regulation of physical exercise is the hippocampus. Here we examined the running activity of Spontaneously-Running-Tokushima-Shikoku (SPORTS) rat, a new animal model for high levels of wheel-running activity, and its relation with the hippocampal norepinephrine (NE) system including the levels of NE, adrenergic receptors, and degradation enzymes for monoamines. In the hippocampus of SPORTS rats, the level of NE in extracellular fluid was augmented, whereas the level in the homogenate of the whole tissue was decreased even for sedentary conditions. Elevated extracellular NE caused downregulation of alpha(2)-adrenergic receptors in the hippocampus of SPORTS rats. Local administration of alpha(2)-adrenergic receptor antagonist yohimbine, but not of alpha(2)-agonist clonidine, into the hippocampus suppressed high running activity in SPORTS rats. The protein expression and the activity levels of monoamine oxidase A (MAOA), a critical enzyme for the degradation of NE, were decreased in the hippocampus of SPORTS rats to increase extracellular NE level. Thus, inhibition of oxidase activity in normal Wistar rats markedly increased wheel-running activity. These results indicate that decreased MAOA activity, elevation of extracellular NE, and alpha(2)-adrenergic receptors in the hippocampus determine the neural basis of the psychological regulation of exercise behavior in SPORTS rats.

Angiotensin II activates intermediate-conductance Ca2+-activated K+ channels in arterial smooth muscle cells

Angiostensin II (Ang II) regulates the migration and proliferation of vascular smooth muscle cells. Recent studies indicate that intermediate-conductance Ca2+ -activated K+ (IKca) channels have an important role in cell migration and proliferation. It is not known, however, whether the action of Ang II is linked to IKca channel regulation. Here, we investigated the modulation of IKca channels by Ang II in artery smooth muscle cells. Functional IKca channel expression in cultured embryonic rat aorta smooth muscle (A10) cells was studied using the patch-clamp technique. These cells predominantly express IKca channels. In contrast, large-conductance Ca2+ -activated K+ (BKca) currents were rarely observed in excised patches. Ang II increased the IKca current in a contration-dependent manner. Losartan (1.0 microM), an AT1 selective antagonist, abolished the activation of IKca channels by Ang II. Pretreatment with 100 microM myristoylated protein kinase C inhibitor peptide 20-28 or 10 microM GF109203X completely abolished the AngII-induced activation of IKca currents, whereas the action of Ang II was not prevented in the presence of 100 microM Rp-cyclic 3', 5'-hydrogen phosphotiate adenosine triethylammonium, a protein kinase A inhibitor, or 1.0 microM KT-5823, a protein kinase G inhibitor. A membrane permeant analogue of diacylglycerol 1, 2-dioctanoyl-sn-glycerol (10 microM) induced the activation of IKca currents. These data suggest that Ang II activates IKca channels through the activation of protein kinase C, and the AT1 receptor is involved in the regulation of these channels.

Pore formation of thermostable direct hemolysin secreted from Vibrio parahaemolyticus in lipid bilayers

Vibrio parahaemolyticus secretes thermostable direct hemolysin (TDH), a major virulence factor. Earlier studies report that TDH is a pore-forming toxin. However, the characteristics of pores formed by TDH in the lipid bilayer, which is permeable to small ions, remain to be elucidated. Ion channel-like activities were observed in lipid bilayers containing TDH. Three types of conductance were identified. All the channels displayed relatively low ion selectivity, and similar ion permeability. The Cl- channel inhibitors, DIDS, glybenclamide, and NPPB, did not affect the channel activity of pores formed by TDH. R7, a mutant toxin of TDH, also forms pores with channel-like activity in lipid bilayers. The ion permeability of these channels is similar to that of TDH. R7 binds cultured cells and liposomes to a lower extent, compared to TDH. R7 does not display significant hemolytic activity and cell cytotoxicity, possibly owing to the difficulty of insertion into lipid membranes. Once R7 is assembled within lipid membranes, it may assume the same structure as TDH. The authors propose that the single glycine at position 62, substituted with serine in the R7 mutant toxin, plays an important role in TDH insertion into the lipid bilayer.

Haemolysin produced by Vibrio mimicus activates two Cl- secretory pathways in cultured intestinal-like Caco-2 cells

Haemolysin (VMH) is a virulent factor produced by Vibrio mimicus, a human pathogen that causes diarrhoea. As intestinal epithelial cells are the primary targets of haemolysin, we investigated its effects on ion transport in human colonic epithelial Caco-2 cells. VMH increased the cellular short circuit current (Isc), used to estimated ion fluxes, and 125I efflux of the cells. The VMH-induced increases in Isc and 125I efflux were suppressed by depleting Ca2+ from the medium or by pretreating the cells with BAPTA-AM or by Rp-adenosin 3',5'-cyclic monophosphorothioate triethylammonium salt (Rp-cAMPS). The Cl- channel inhibitors 4,4'-disothiocyanatostibene-2,2'-disulfonic acid (DIDS), glybenclamide, and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) suppressed the VMH-induced increases in Isc and 125I efflux. Moreover, VMH increased the intracellular concentrations of Ca2+ and cAMP. Thus, VMH stimulates Caco-2 cells to secrete Cl- by activating both Ca2+ -dependent and cAMP-dependent Cl- secretion mechanisms. VMH forms ion-permeable pores in the lipid bilayer that are non-selectively permeable to small ions. However, the ion permeability of these pores was not inhibited by glybenclamide and DIDS, and VMH did not change the cell membrane potential. These observations indicate that the pores formed on the cell membrane by VMH are unlikely to be involved in VMH-induced Cl- secretion. Notably, VMH stimulated fluid accumulation in the iliac loop test that was fully suppressed by a combination of DIDS and glybenclamide. Thus, Ca2+-dependent and cAMP-dependent Cl- secretion may be important therapeutic targets with regard to the diarrhoea that is induced by Vibrio mimicus.

Molecular cloning of a murine glycerol-3-phosphate acyltransferase-like protein 1 (xGPAT1)

A novel murine glycerol-3-phosphate acyltransferase-like protein 1 (named xGPAT1) has been cloned. The mouse xGPAT1 gene is located on mouse Chromosome 2, spans >19 kb, and consists of at least 23 exons. The protein is 32% identical and 72% similar to mouse mitochondrial GPAT (mtGPAT) on the amino acid level. Sequencing analysis confirmed that xGPAT1 has a 2403-bp open reading frame (ORF) that encodes an 801-amino acid protein with an estimated molecular mass of 89.1 kDa. A hydropathy plot of the deduced xGPAT1 protein showed a high degree of similarity with that of the mtGPAT protein. Using 5'-rapid amplification of cDNA ends, two alternate, untranslated exon 1 (1a and b) isoforms were obtained, generating variants xGPAT1-v1 and xGPAT1-v2. xGPAT1-v1 is expressed in mouse heart, liver, spleen, kidney and murine inner medullary collecting duct 3 (mIMCD3) cells, while xGPAT1-v2 is expressed in mouse liver, spleen, kidney, white and brown adipose tissues and 3T3-L1 pre- and post-adipocytes. xGPAT1 was distributed in the membrane fraction and showed GPAT activity when epitope-tagged xGPAT1 was expressed in Chinese hamster ovary (CHO)-K1 cells.

Ginsenoside Re, a main phytosterol of Panax ginseng, activates cardiac potassium channels via a nongenomic pathway of sex hormones

Ginseng root is one of the most popular herbs throughout the world and is believed to be a panacea and to promote longevity. It has been used as a medicine to protect against cardiac ischemia, a major cause of death in the West. We have previously demonstrated that ginsenoside Re, a main phytosterol of Panax ginseng, inhibits Ca(2+) accumulation in mitochondria during cardiac ischemia/reperfusion, which is attributable to nitric oxide (NO)-induced Ca(2+) channel inhibition and K(+) channel activation in cardiac myocytes. In this study, we provide compelling evidence that ginsenoside Re activates endothelial NO synthase (eNOS) to release NO, resulting in activation of the slowly activating delayed rectifier K(+) current. The eNOS activation occurs via a nongenomic pathway of each of androgen receptor, estrogen receptor-alpha, and progesterone receptor, in which c-Src, phosphoinositide 3-kinase, Akt, and eNOS are sequentially activated. However, ginsenoside Re does not stimulate proliferation of androgen-responsive LNCaP cells and estrogen-responsive MCF-7 cells, implying that ginsenoside Re does not activate a genomic pathway of sex hormone receptors. Fluorescence resonance energy transfer experiments with a probe, SCCoR (single cell coactivator recruitment), indicate that the lack of genomic action is attributable to failure of coactivator recruitment. Thus, ginsenoside Re acts as a specific agonist for the nongenomic pathway of sex steroid receptors, and NO released from activated eNOS underlies cardiac K(+) channel activation and protection against ischemia-reperfusion injury.

Effect of TRB3 on insulin and nutrient-stimulated hepatic p70 S6 kinase activity

Insulin and nutrients activate hepatic p70 S6 kinase (S6K1) to regulate protein synthesis. Paradoxically, activation of S6K1 also leads to the development of insulin resistance. In this study, we investigated the effect of TRB3, which acts as an endogenous inhibitor of Akt, on S6K1 activity in vitro and in vivo. In cultured cells, overexpression of TRB3 completely inhibited insulin-stimulated S6K1 activation by mammalian target of rapamycin, whereas knockdown of endogenous TRB3 increased both basal and insulin-stimulated activity. In C57BL/6 mice, adenoviral overexpression of TRB3 inhibited insulin-stimulated activation of hepatic S6K1. In contrast, overexpression of TRB3 did not inhibit nutrient-stimulated S6K1 activity. We also investigated the effect of starvation, feeding, or insulin treatment on TRB3 levels and S6K1 activity in the liver of C57BL/6 and db/db mice. Both insulin and feeding activate S6K1 in db/db mice, but only insulin activates in the C57BL/6 strain. TRB3 levels were 3.5-fold higher in db/db mice than C57BL/6 mice and were unresponsive to feeding or insulin, whereas both treatments reduced TRB3 in C57BL/6 mice. Akt was activated by insulin alone in the C57BL/6 strain and but not in db/db mice. Both insulin and feeding activated mammalian target of rapamycin similarly in these mice; however, feeding was unable to activate the downstream target S6K1 in C57BL/6 mice. These results suggest that the nutrient excess in the hyperphagic, hyperinsulinemic db/db mouse primes the hepatocyte to respond to nutrients resulting in elevated S6K1 activity. The combination of elevated TRB3 and constitutive S6K1 activity results in decreased insulin signaling via the IRS-1/phosphatidylinositol 3-kinase/Akt pathway.

Efficacy of glimepiride on insulin resistance, adipocytokines, and atherosclerosis

BACKGROUND

Plasma adiponectin levels increase after the administration of glimepiride. This unique effects would also be expected to improve other adipocytokines and have anti-atherosclerotic action in patients with metabolic syndrome.

METHODS

Thirty-four patients with type 2 diabetes mellitus who were administrated glibenclamide were randomly divided into two groups. In 20 patients glibenclamide was changed to glimepiride (GP group), and the administration of glibenclamide (GB group) was continued in 14 patients. Twelve patients receiving insulin therapy (INS group) were enrolled for comparison. The levels of plasma adiponectin, high sensitive-CRP, TNF-alpha, interleukin-6, homeostasis model assessment-insulin resistance (HOMA-IR), brachial-ankle pulse wave velocity (baPWV) and augmentation index (AI) were measured before and 28 weeks after the therapy.

RESULTS

HOMA-IR in the GP group was significantly decreased compared to the GB group. Plasma adiponectin levels were significantly increased in the GP group but not in the other groups. TNF-alpha, interleukin-6 and high sensitive-CRP levels were significantly decreased in the GP group, but not in the other groups. The baPWV and AI levels did not change in either the GB or the INS group, but were significantly decreased in the GP group.

CONCLUSIONS

Glimepiride appears to improve insulin resistance and atherosclerotic disorders.

Relationship between adhesion molecules with hs-CRP and changes therein after ARB (Valsartan) administration in patients with obstructive sleep apnea syndrome

It has been reported that a relationship exists between obstructive sleep apnea syndrome (OSAS) and cardiovascular and cerebrovascular diseases. To address this issue, we evaluated whether OSAS is associated with adhesion molecules and inflammatory signs, important indicators of atherosclerosis. Levels of high-sensitivity CRP (hs-CRP) and intercellular adhesion molecule-1 (ICAM-1) were measured in 30 patients with ischemic heart disease, confirmed by coronary arteriography (IHD group). Twenty healthy volunteers without sleep apnea were used as controls (Group N). Sleeping respiratory information was collected using a portable sleep polygraph, together on information about oronasal flow, tracheal sound, chest respiration, and percutaneous oxygen saturation (SpO2) to obtain the apnea-hypopnea index (AHI). In the IHD group, 9 (30%) of the 30 patients showed evidence of OSAS [IHD(AHI> or = 40) group] and 21 did not [IHD(AHI<40) group]. The levels of hs-CRP and ICAM-1 were significantly higher in the IHD group than in the N group (p<0.01). Moreover, the levels of hs-CRP and ICAM-1 were significantly higher in the IHD(AHI > or = 40) group than in the IHD(AHI<40) group (p<0.01). However, after the administration of valsartan, angiotensin II receptor antagonists (ARB) to both IHD groups, the levels of hs-CRP and ICAM-1 decreased significantly in both groups. Moreover, a multivariate analysis revealed that the levels of hs-CRP and ICAM-1 were associated with the severity of sleep apnea. These findings suggest that, in OSAS the levels of hs-CRP and ICAM-1 are decreased and that the administration of ARB decreases the risk of atherosclerosis.

123I-metaiodo-benzylguanidine myocardial scintigraphy in the Brugada-type ECG

The degree of ST-segment elevation and amplitude of J waves, which may change in patients with the Brugada-type electrocardiogram (ECG) over time, are influenced by autonomic nervous activity and the administration of antiarrhythmic drugs. In the present study, we evaluated whether the shape of ST-segment elevation in patients with a Brugada-type ECG might alter the parameters of an 123I-MIBG myocardial scintigraphy and body surface signal-averaged ECG (SAECG). The subjects consisted of 12 patients with a Brugada-type ECG and 15 healthy volunteers (N group). The patients with a Brugada-type ECG were classified into the following 2 groups based on the type of ST-segment elevation: 6 patients with the coved type ST-segment elevation (C group), and 6 patients with the saddle-back type ST-segment elevation (S group). Planar and SPECT images were obtained 15 minutes (early images) and 3 hours (delayed images) after the administration of 123I-MIBG, respectively. In addition, the washout rate (% WR) of 123I-MIBG was obtained in a bull's eye map of the SPECT image. There were no significant differences in the early H/M ratio between the C and S groups. In the C group, however, there were some patients who showed a decreased accumulation or defect of 123I-MIBG in the planar and SPECT images. Furthermore, in contrast to the N and S groups, the C group showed a decreased delayed H/M ratio and increased % WR. SAECG did not show any significant differences between the S and C groups. These results of the present study suggest that the shape of ST-segment elevation may be associated with myocardial autonomic nervous function. In addition, the electric heterogeneity of the action potential in the right ventricular epicardial myocardium, which is frequently influenced by autonomic nervous activity, is closely associated with the development of Brugada syndrome.

Evaluation of episodes of sleep apnea in patients with liver cirrhosis

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) has been reported to be a new complication of liver cirrhosis with ascites. This fact prompted a study of episodes of sleep apnea as a function of the severity of cirrhosis.

METHODS

Forty eight patients with type C liver cirrhosis were divided according to the Child-Pugh score into 3 groups: Group A (16 patients with grade A cirrhosis), Group B (16 patients with grade B cirrhosis), and Group C (16 patients with grade C cirrhosis). Portable sleep polygraphs (Fuji RC, Inc. Tokyo, Japan) were attached to the subjects, and oronasal respiration, tracheal sounds, respiratory movements of the chest, and percutaneous arterial oxygen saturation continuously were recorded. A decrease in the mean airflow to 50% or less was defined as hypopnea, and the number per hour of episodes of apnea and hypopnea per hour lasting 10 seconds or longer (AHI) was counted. A Holter ECG was also recorded, and spectral heart rate variability during sleep was analyzed by measuring low frequency power (0.04-0.15 Hz, LF power), high frequency power (0.15-0.40 Hz, HF power), the ratio of LF power to HF power (LF/HF ratio), and very low frequency power (0.008-0.04 Hz, VLF power). The difference in QT interval between the lead CM5 and the lead CM1 (QTc dispersion) was also examined.

RESULTS

AHI was significantly higher in Group C than in Groups A and B (p<0.05). In Group C, 6 patients with 20 times or more AHI per hour, obstructive sleep apnea, in which respiratory chest movements occur but oronasal respiration decreases or disappears, was observed. Spectral analyses of heart rate variability showed a decrease in HF power without sleep apnea, but increases in HF power and VLF power were observed during sleep apnea. The QTc dispersion increased during episodes of sleep apnea.

CONCLUSIONS

As the stage of liver cirrhosis advanced, sleep apnea appeared, and changes in autonomic nervous activities were observed. Furthermore, QTc dispersion was increased during episodes of sleep apnea, presumably increasing the risk of ventricular arrhythmia.

Aeromonas sobria hemolysin causes diarrhea by increasing secretion of HCO3−

Aeromonas sobria hemolysin (ASH) is one of the major virulence factors produced by A. sobria, a causative agent of diarrhea in humans. We investigated the effects of ASH on anion transport in human colonic epithelial cells. ASH increased short circuit currents across the intestinal epithelia, which were suppressed by anion channel antagonists, such as carbonic anhydrase inhibitors, and by the removal of external HCO3-. Iliac fluid accumulation was also inhibited by carbonic anhydrase inhibitors. The results suggest that ASH activates HCO3- secretion, whose level correlates with the severity of diarrhea.

Exposure to music in the perinatal period enhances learning performance and alters BDNF/TrkB signaling in mice as adults

Music has been suggested to have a beneficial effect on various types of performance in humans. However, the physiological and molecular mechanism of this effect remains unclear. We examined the effect of music exposure during the perinatal period on learning behavior in adult mice, and measured the levels of brain-derived neurotrophic factor (BDNF) and its receptor, tyrosine kinase receptor B (TrkB), which play critical roles in synaptic plasticity. In addition, we measured the levels of 3-phosphoinositide-dependent protein kinase-1 (PDK1) and mitogen-activated protein kinase (MAPK), downstream targets of two main pathways in BDNF/TrkB signaling. Music-exposed mice completed a maze learning task with fewer errors than the white noise-exposed mice and had lower levels of BDNF and higher levels of TrkB and PDK1 in the cortex. MAPK levels were unchanged. Furthermore, TrkB and PDK1 protein levels in the cortex showed a significant negative correlation with the number of errors on the maze. These results suggest that perinatal exposure of mice to music has an influence on BDNF/TrkB signaling and its intracellular signaling pathway targets, including PDK1, and thus may induce improved learning and memory functions.

Sarpogrelate hydrochloride, an antagonist of 5-hydroxytryptamine receptor, improves skin flap survival and suppresses thrombus formation in injured microvessels of rabbits

The authors carried out two studies to examine the effects of the 5-hydroxytryptamine receptor antagonist, sarpogrelate hydrochloride (SH), on flap necrosis. The first study measured survival rates and included histologic examination of random-pattern skin flaps in rabbits. The second study assessed the time to complete obstruction of blood flow with the artificial thrombus formation method, and the time for leukocytes to adhere to the endothelium of microvessels in a rabbit-ear chamber. The treatment groups were injected with SH. The survival rates of skin flaps in the SH-treated group were increased significantly. Histologic examination of vessels in the control group revealed that vessels in the deep dermis were obstructed completely by thrombi, whereas such vessels were not obstructed in the SH-treated group. Thrombus formation time and leukocyte adhesion time in the SH-treated group were prolonged and decreased, respectively. Thus, SH maintained flap circulation and promoted flap survival by preventing thrombus formation.

Human airway trypsin-like protease stimulates human bronchial fibroblast proliferation in a protease-activated receptor-2-dependent pathway

Human airway trypsin-like protease (HAT) was isolated from airway secretions and localized to bronchial epithelial cells by immunohistochemistry. In the present study, we examined whether HAT could stimulate DNA synthesis and proliferation of primary human bronchial fibroblasts (HBF). HAT significantly stimulated the proliferation of HBF by 20–55%, a level similar to that of the mitogenic activity of lung mast cell tryptase (MCT). HAT also stimulated the incorporation of [3H]thymidine in HBF, and this HAT-induced DNA synthesis was abolished by leupeptin. Protease-activated receptor-2 (PAR-2) mRNA was expressed and localized to the cell surface in HBF. PAR-2 activating peptide (AP) also enhanced DNA synthesis, and both HAT and PAR-2 AP induced receptor internalization, similar to the response to trypsin. Pretreatment of HBF with anti-PAR-2 antibody significantly suppressed both HAT and PAR-2 AP-induced DNA synthesis. In addition, HAT and PAR-2 AP induced intracellular Ca2+mobilization in HBF. The HAT-induced increase in Ca2+was desensitized by pretreatment with trypsin or PAR-2 AP. U0126, a specific MAPK inhibitor, completely inhibited HAT-induced DNA synthesis as well as HAT-induced phosphorylation of MAPK. The effect of HAT and MCT together was additive, whereas the effect of HAT and insulin together on HBF DNA synthesis was synergistic. These results indicate that HAT stimulates fibroblast proliferation in bronchial airways through a PAR-2-dependent MEK-MAPK mediated pathway and that HAT is linked to airway processes involving fibroblasts.

Effects of thrombus suction therapy on myocardial blood flow disorders in males with acute inferior myocardial infarction

Several studies have reported that the use of a distal protection device decreases the incidence of slow-flow and/or no-reflow in patients with myocardial infarctions. In the present study, we investigated the influence of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter on coronary microcirculation disorders in patients with acute myocardial infarction using the natriuretic polypeptide (ANP), the brain natriuretic peptide (BNP), and (99m)Tc-tetrofosmin myocardial scintigraphy (TF). The group consisted of a 77 patients with initial inferior myocardial infarction who had undergone emergency coronary angioplasty. The patients were randomly divided into: Group D (n=28), in which a direct stent alone was inserted, Group R/T (n=25), in which a stent was inserted after RESCUE system or a Thrombuster system was performed, and Group P (n=24), in which a stent was inserted after thrombus suction using a PercuSurge GuardWire catheter. Patients with coronary slow-flow/no-reflow were 3, 2 and 0 cases in Group D, Group R / T and Group P, respectively. In the present study, patients with good-reflow were enrolled in order to investigate the coronary microcirculation disorder in patients with visually similar coronary blood flow obtained in coronary angiography after percutaneous coronary reperfusion therapy. TF myocardial scintigraphy was performed 10+/-3 days after admission. Bull's eye images were divided into 8 sections, and each section was evaluated in 4 grades. The grade of each segment was regarded as the defect score. The results were compared with the database prepared based on bull's eye maps from 50 healthy adults in our hospital, and count areas of -2 x SD (standard deviation) or less were calculated as the extent score (%), reflecting the area in which myocardial blood flow was decreased. The extent and severity scores in Groups P and R/T were significantly lower than those in Group D. Coronary angiography at the chronic stage (6 months after surgery) showed the patency of the responsible vascular lesion in all patients. However, the ANP, BNP, cardiac index, and pulmonary capillary wedge pressure (PCWP) were significantly improved in Groups R/T and P, compared to Group D (p<0.01). These results suggest that the use of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter system in patients with acute inferior wall infarction improves coronary microcirculation disorders and acute- to chronic-phase cardiac function.

Relationships between thermic effect of food, insulin resistance and autonomic nervous activity

BACKGROUND

The thermic effect of food (TEF) is higher in lean than in obese human subjects.

OBJECTIVE

Relationships between TEF and insulin resistance during meals, from the point of view of autonomic nervous activity, were evaluated.

METHODS

Autonomic nervous activity was evaluated in 20 young adults using the spectral analysis of heart rate variability from one hour before to two hours after a meal. Heart rate data were analyzed based on low frequency components (LF power, 0.04-0.15 Hz), high frequency components (HF power, 0.15-0.40 Hz), and LF/HF ratios. Energy expenditure and the TEF were measured 30 min after a meal. Homeostasis model of insulin resistance index (HOMA-IR) was also measured.

RESULTS

The LF/HF ratio was significantly increased 30 min after a meal (p<0.05). No correlation between LF power and HF power with TEF was found, but the LF/HF ratio was significantly and positively correlated with TEF (r=+0.56, p<0.05). Moreover, a significant negative correlation was found between the HOMA-IR and TEF (r=-0.601, p<0.05).

CONCLUSIONS

The findings suggest that a reduction in insulin sensitivity induces a poor response of sympathetic nervous activity in the postprandial phase and a reduction in postprandial energy expenditure.

Nateglinide with glibenclamide examination using the respiratory quotient (RQ)

PURPOSE

The respiratory quotient (RQ) is useful for evaluating glucose and lipid metabolism in vivo. We previously reported that the RQ value, even after fasting, was high in diabetics being treated with sulphonylurea (SU), which might explain the accumulation of fat, leading to weight gain in such individuals. In the present study, we measured the RQ in type II diabetic patients who were being treated with a rapid-onset/short-duration insulinotropic agent, nateglinide, and compared it with those being treated with SU.

METHODS

A glucose tolerance test was performed in 20 patients with type II diabetes mellitus treated with nateglinide and in 14 patients treated with SU, and the RQ was simultaneously measured.

RESULTS

The RQ values in the patients treated with nateglinide, were similar to those in healthy adults, but was lower than in those treated with SU. No weight gain was observed in patients treated with nateglinide.

CONCLUSION

A significant weight gain was reported in subjects treated with SU, accompanied by an increase in RQ. However, weight gain was less frequent in diabetics treated with nateglinide.

Antidepressant Effect of Extracts from Ginkgo biloba Leaves in Behavioral Models

Extracts of Ginkgo biloba (EGB) are a complex product prepared from green leaves of the Ginkgo biloba tree. In the present study, the antidepressant effect of EGB was examined using two behavioral models, the forced swimming test (FST) in rats and tail suspension test (TST) in mice. EGB significantly reduced immobility time in the FST at a dosage of 10 and 50 mg/kg body weight after repeated oral treatment for 14 d, although no change of motor dysfunction was observed with the same dosage in the open field test. These results indicate that EGB might possess an antidepressant activity. In addition, EGB markedly shortened immobility time in the TST after acute inter-peritoneal treatment at a dosage of 50 and 100 mg/kg body weight. The present study clearly demonstrated that EGB exerts an antidepressant effect in these two behavioral models.