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Objective: To study the effect of intermittent hypoxia training (IHT) for dizziness. Design: A single-blind, randomized controlled trial. All participants were recruited from a rehabilitation department in an acute university-affiliated hospital. Intervention: Participants with dizziness were randomly assigned to 2 groups (IHT group and control group). The Dizziness Handicap Inventory, Activities-specific Balance Confidence Scale, and Vertigo Visual Analog Scale were conducted at baseline, end of the fourth week. Results: Among 52 subjects, there were18 males and 34 females, ages 35 to 62 years old (mean [SD] = 46.9 [7.93]). Time length since onset ranged from 12 to 34 months (20.2 [7.15] mo). Dizziness Handicap Inventory, Activities-specific Balance Confidence Scale, Vertigo Visual Analog Scale scores, and attack frequencies of dizziness were improved after IHT intervention in the end of the fourth week. There were significant differences between the IHT group and the control group in the Dizziness Handicap Inventory, Activities-specific Balance Confidence Scale, Vertigo Visual Analog Scale scores, and attack frequencies of dizziness at the end of the fourth week (P Conclusion: IHT could improve dizziness after intervention at the end of the fourth week. IHT could be the effective method for treating dizziness.

The capture of circulating tumor cells (CTCs) is still a challenging application for microfluidic chips, as these cells are rare and hidden in a huge background of blood cells. Here, different microfluidic ceiling designs in regard to their capture efficiency for CTCs in model experiments and more realistic conditions of blood samples spiked with a clinically relevant amount of tumor cells are evaluated. An optimized design for the capture platform that allows highly efficient recovery of CTCs from size-based pre-enriched samples under realistic conditions is obtained. Furthermore, the viability of captured tumor cells as well as single cell recovery for downstream genomic analysis is demonstrated. Additionally, the authors' findings underline the importance of evaluating rational design rules for microfluidic devices based on theoretical models by application-specific experiments.

Objective: To study the effect of therapeutic exercise on knee osteoarthritis after injection of botulinum toxin type A, hyaluronate or saline. Methods: Sixty participants with knee osteoarthritis were randomly assigned to 3 groups: injection of saline (control) (group A), botulinum toxin type A (group B), or hyaluronate (group C). All participants received therapeutic exercise. Western Ontario and McMaster Universities Osteoarthritis Index questionnaire score, visual analogue scale pain scale, and Medical Outcomes Study 36-item Health Survey were conducted at baseline, and at the end of the 4th and 8th weeks. Results: At end of the 4th and 8th weeks, the scores on the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire and visual analogue scale were higher in the control group. There were significant differences in Physical Component Summary-36 and Mental Component Summary-36 scores between the 3 groups (p

The ability to induce osteointegration was introduced to a parylene-C surface via the simple and intuitive process of protein adsorption mediated by hydrophobic interactions. In this way, bone morphogenetic protein (BMP)-2, fibronectin, and platelet-rich plasma (PRP) could be immobilized on parylene-C surfaces. This approach alleviates concerns related to the use of potentially harmful substances in parylene-C modification processes. The adsorbed protein molecules were quantitatively characterized with respect to adsorption efficacy and binding affinity, and the important biological activities of the proteins were also examined using both early and late markers of osteogenetic activity, including alkaline phosphatase expression, calcium mineralization and marker gene expression. Additionally, the adsorbed PRP exhibited potential as a substitute for expensive recombinant growth factors by effectively inducing comparable osteogenetic activity. In addition to the excellent biocompatibility of parylene-C and its ability to coat a wide variety of substrate materials, the modification of parylene-C via protein adsorption provides unlimited possibilities for installing specific biological functions, expanding the potential applications of this material to include various biointerface platforms.

Multifunctional biomaterial surfaces can be created by controlling the competing adsorption of multiple proteins. To demonstrate this concept, bone morphogenetic protein 2 (BMP-2) and fibronectin were adsorbed to the hydrophobic surface of polychloro-para-xylylene. The resulting adsorption properties on the surface depended on the dimensional and steric characteristics of the selected protein molecule, the degree of denaturation of the adsorbed proteins, the associated adsorption of interphase water molecules within the protein layers, and the aggregation of proteins in a planar direction with respect to the adsorbent surface. Additionally, a defined surface composition was formed by the competing adsorption of multiple proteins, and this surface composition was directly linked to the composition of the protein mixture in the solution phase. Although the mechanism of this complex competing adsorption process is not fully understood, the adsorbed proteins were irreversibly adsorbed and were unaffected by the further adsorption of homologous or heterologous proteins. Moreover, synergistic biological activities, including cell osteogenesis and proliferation independently and specifically induced by BMP-2 or fibronectin, were observed on the modified surface, and these biological activities were positively correlated with the surface composition of the multiple adsorbed proteins. These results provide insights and important design parameters for prospective biomaterials and biointerfaces for (multi)functional modifications. The ability to control protein/interface properties will be beneficial for the processing of biomaterials for clinical applications and industrial products.

Obesity is an unconstrained worldwide epidemic. Unraveling molecular controls in adipose tissue development holds promise to treat obesity or diabetes. Although numerous immortalized adipogenic cell lines have been established, adipose-derived stem cells from the stromal vascular fraction of subcutaneous white adipose tissues provide a reliable cellular system ex vivo much closer to adipose development in vivo. Pig adipose-derived stem cells (pADSC) are isolated from 7- to 9-day old piglets. The dorsal white fat depot of porcine subcutaneous adipose tissues is sliced, minced and collagenase digested. These pADSC exhibit strong potential to differentiate into adipocytes. Moreover, the pADSC also possess multipotency, assessed by selective stem cell markers, to differentiate into various mesenchymal cell types including adipocytes, osteocytes, and chondrocytes. These pADSC can be used for clarification of molecular switches in regulating classical adipocyte differentiation or in direction to other mesenchymal cell types of mesodermal origin. Furthermore, extended lineages into cells of ectodermal and endodermal origin have recently been achieved. Therefore, pADSC derived in this protocol provide an abundant and assessable source of adult mesenchymal stem cells with full multipotency for studying adipose development and application to tissue engineering of regenerative medicine.

Subjects with type 1 diabetes mellitus (T1DM) eventually develop insulin resistance and other features of T2DM such as cardiovascular disorders. The exact mechanism has been not been completely understood. In this study, we tested the hypothesis that excessive or inappropriate exposure to insulin is a primary mediator of insulin resistance in T1DM. We found that continuous exposure of mice with non-obese diabetes to insulin detemir, which is similar to some current conventional treatment of human T1DM, induced severe insulin resistance, whereas untreated hyperglycemia for the same amount of time (2 weeks) did not cause obvious insulin resistance. Insulin resistance was accompanied by decreased mitochondrial production as evaluated by mitochondrial DNA and levels of transcripts and proteins of mitochondrion-associated genes, increased ectopic fat accumulation in liver and skeletal muscle (gastrocnemius) evaluated by measurements of triglyceride content, and elevated oxidative stress detected by the GSH/GSSG ratio. Prolonged exposure of cultured hepatocytes to insulin induced significant insulin resistance, whereas the same length of exposure to a high level of glucose (33 mm) did not cause obvious insulin resistance. Furthermore, our results showed that prolonged exposure to insulin caused oxidative stress, and blockade of mitochondrion-derived oxidative stress by overexpression of manganese-superoxide dismutase prevented insulin resistance induced by the prolonged exposure to insulin. Together, our results show that excessive exposure to insulin is a primary inducer of insulin resistance in T1DM in mice.

Insulin is the central regulator of metabolism and is necessary for storing energy as fat efficiently. Mitochondria are primary sites of energy consumption of most cells. Increased plasma insulin level and mitochondrial dysfunction are features of insulin resistance. The exact role of insulin in regulation of mitochondrial production and function remains unestablished. In this study, we observed that mitochondrial production in liver and skeletal muscle gastrocnemius was increased in mice with insulin deficiency (streptozotocin-induced type 1 diabetes). In contrast, prolonged exposure (24 h) of isolated hepatocytes to insulin decreased mitochondrial mass, mitochondrial DNA (mtDNA), intracellular ATP content, and cellular O2 consumption. Transcript levels of genes associated with mitochondrial production and β oxidation were decreased, whereas those of lipogenic genes were increased by the prolonged exposure to insulin. Insulin-induced changes in mtDNA, mitochondrial mass, intracellular ATP content, and transcripts of mitochondrion-associated genes were prevented by blockade of Akt activation with the phosphatidylinositol 3-kinase inhibitor LY294002. Conversely, levels of mtDNA, intracellular ATP content, and expression of mitochondrion-associated genes were decreased by overexpression of the constitutively active Akt. Finally, insulin suppression of mtDNA, ATP production, and expression of mitochondrion-related genes was largely prevented by inhibition of cyclic nucleotide phosphodiesterase with isobutylmethylxanthine. Together, our results show prolonged exposure of isolated hepatocytes to insulin suppresses mitochondrial production and function through the classical Akt-dependent insulin signaling pathway.

The proinflammatory cytokine interleukin (IL)-6 has been proposed to be one of the mediators that link obesity-derived chronic inflammation with insulin resistance. Signaling through the mammalian target of rapamycin (mTOR) has been found to impact insulin sensitivity under various pathological conditions, through serine phosphorylation and inhibition of insulin receptor substrate by the downstream effector of mTOR, ribosomal S6 kinase 1 (S6K1). However, an involvement of mTOR in IL-6-induced insulin resistance has not yet been reported. Here we show that rapamycin, the inhibitor of mTOR signaling, rescues insulin signaling and glycogen synthesis from IL-6 inhibition in HepG2 hepatocarcinoma cells as well as in mouse primary hepatocytes. IL-6 activates S6K1 in these cells, but unexpectedly, S6K1 is not involved in IL-6 inhibition of insulin signaling, since the effect of IL-6 persists in cells with drastically reduced S6K1 levels induced by RNA interference, suggesting that the function of mTOR signaling is through a mechanism different from the prevailing model of S6K1 phosphorylation of insulin receptor substrate-1. Interestingly, we find that the phosphorylation of STAT3 on Ser(727) and STAT3 transcriptional activity are regulated by mTOR upon IL-6 stimulation and that STAT3 is required for IL-6 inhibition of insulin signaling. Furthermore, IL-6-induced SOCS3 expression is inhibited by rapamycin, and ectopic expression of SOCS3 blocks the ability of rapamycin to enhance insulin sensitivity in the presence of IL-6. Taken together, we propose that mTOR plays a key role in IL-6-induced hepatic insulin resistance by regulating STAT3 activation and subsequent SOCS3 expression.

Human neutrophil peptides (HNP) kill microorganisms but also modulate immune responses through upregulation of the chemokine IL-8 by activation of the nucleotide P2Y(6) receptor. However, the intracellular signaling mechanisms remain yet to be determined. Human lung epithelial cells (A549) and monocytes (U937) were stimulated with HNP in the absence and presence of the specific kinase inhibitors for Src, extracellular signal-regulated kinase-1 and -2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), c-Jun-N-terminal kinases (JNK), and Akt. HNP induced a rapid phosphorylation of the kinases in both cell types associated with a dose-dependent, selective production of IL-8 among 10 cytokines assayed. The HNP-induced IL-8 production was blocked by the Src tyrosine kinase inhibitor PP2, MEK1/2 inhibitor U0126, and the phosphatidylinositol 3 kinase (PI3K) inhibitor LY294002, but not by the JNK inhibitor SP600125 in both cell types. Treatment with the p38 inhibitor SB203580 attenuated the HNP-induced IL-8 production only in monocytes. Blockade of Src kinase blunted HNP-induced phosphorylation of the ERK1/2 and Akt but not p38 in monocytes. In contrast, Src inhibition had no effect on phosphorylation of the other kinases in the lung epithelial cells. We conclude that the activation of ERK1/2 and PI3K/Akt pathways is required for HNP-induced IL-8 release which occurs in a Src-independent manner in lung epithelial cells, while is Src-dependent in monocytes.

The human tumorous imaginal disc 1 (TID1) proteins including TID1(L) and TID1(S), members of the DnaJ domain protein family, are involved in multiple intracellular signaling pathways such as apoptosis induction, cell proliferation, and survival. Here we report that TID1 associates with the Trk receptor tyrosine kinases and regulates nerve growth factor (NGF)-induced neurite outgrowth in PC12-derived nnr5 cells. Binding assays and transfection studies showed that the carboxyl-terminal end of TID1 (residues 224-429) bound to Trk at the activation loop (Tyr(P)(683)-Tyr(684)(P)(684) in rat TrkA) and that TID1 was tyrosine phosphorylated by Trk both in yeast and in transfected cells. Moreover endogenous TID1 was also tyrosine phosphorylated by and co-immunoprecipitated with Trk in neurotrophin-stimulated primary rat hippocampal neurons. Overexpression studies showed that both TID1(L) and TID1(S) significantly facilitated NGF-induced neurite outgrowth in TrkA-expressing nnr5 cells possibly through a mechanism involving increased activation of mitogen-activated protein kinase. Consistently knockdown of endogenous TID1, mediated with specific short hairpin RNA, significantly reduced NGF-induced neurite growth in nnr5-TrkA cells. These data provide the first evidence that TID1 is a novel intracellular adaptor that interacts with the Trk receptor tyrosine kinases in an activity-dependent manner to facilitate Trk-dependent intracellular signaling.

The human beta1-adrenoceptor (beta1AR) and beta2-adrenoceptor (beta2AR) couple to Gs-proteins to activate adenylyl cyclase (AC). There are differences in desensitization between the beta2AR and the originally cloned Gly389-beta1AR, but with respect to ternary complex formation, constitutive activity, and AC activation the picture is unclear. To learn more about the similarities and differences between the beta1AR and beta2AR, we analyzed coupling of the Gly389-beta1AR to the G(s(alpha)) splice variants Gs(alpha)L and Gs(alpha)S using beta1AR-Gs(alpha) fusion proteins expressed in Sf9 cells and compared the data with previously published data on beta2AR-Gs(alpha) fusion proteins (Seifert et al., J Biol Chem 1998;273:5109-16). Fusion ensures defined receptor/G-protein stoichiometry and efficient coupling. The agonist (-)-isoproterenol stabilized the ternary complex at beta1AR-Gs(alpha)S, beta1AR-Gs(alpha)L, beta2AR-Gs(alpha)S, and beta2AR-Gs(alpha)L with similar efficiency. beta1AR-Gs(alpha)L but not beta1AR-Gs(alpha)S showed the hallmarks of constitutive activity as assessed by increased potencies and efficacies of partial agonists and AC activation by the agonist-free receptor. Similar differences were observed previously for beta2AR-Gs(alpha)S and beta2AR-Gs(alpha)L. beta1AR-Gs(alpha)S and beta2AR-Gs(alpha)S were similarly efficient at activating AC, but beta1AR-Gs(alpha)L was approximately 4-fold more efficient at activating AC than beta2AR-Gs(alpha)L. Our data show that (i) the beta1AR and beta2AR are similarly efficient at stabilizing the ternary complex with Gs(alpha) splice variants, (ii) Gs(alpha)L confers constitutive activity to the beta1AR and beta2AR, and (iii) the beta1AR coupled to Gs(alpha)L is more efficient at activating AC than the beta2AR coupled to Gs(alpha)L. These data help us understand some of the discrepancies regarding similarities and differences between the beta1AR and beta2AR.

More than 10 G protein-coupled receptors (GPCRs) have been reported to act as coreceptors for entry of human and simian immunodeficiency viruses (HIV and SIV). We investigated the utilization of six GPCRs as coreceptors by T-cell-line-adapted HIV-2 strains (CBL-20, CBL-21, CBL-23, GH-1, ROD, and SBL6669) and SIV strains (SIVagmTYO-1, SIVmac251, and SIVmndGB-1). NP-2/CD4 cells were transduced with CCR3, CCR5, CCR8, CXCR4, GPR1, or APJ, and examined for susceptibilities to cell-free HIV/SIV. HIV-2 strains were grouped into two types by their coreceptor usage. The first group, CBL-20 and CBL-21, used CXCR4 exclusively; the other four strains used a few or all of the six coreceptors. These strains could further infect CD4-negative NP-2/CXCR4 or NP-2/CCR5 cells in the presence (all strains) or absence (SBL6669 and ROD strains) of soluble CD4. SIVagm and SIVmnd infected NP-2/CD4/GPR1 cells. The coreceptors CCR3, CCR8, GPR1, and APJ did not mediate the CD4-independent infection. Although HIV-2ROD and SIVmnd infected both NP-2/CD4/CXCR4 and NP-2/CD4/CCR5 cells, only CXCR4 and CCR5, respectively, were used in CD4-independent infection. Binding of virions to CD4-negative cells occurred at 4°C. These findings suggest that there may be a correlation between the promiscuous use of coreceptors by HIV-2/SIV strains and their ability to infect CD4-negative cells.

The orphan G protein-coupled receptor APJ has been shown to be a coreceptor for human and simian immunodeficiency virus (HIV and SIV) strains. We have determined that some HIV and SIV strains use APJ as a coreceptor to infect the brain-derived NP-2/CD4 cells. Because apelin is an endogenous ligand for the APJ receptor, we examined the inhibitory effects of apelin peptides on HIV infection, and found that the apelin peptides inhibit the entry of some HIV-1 and HIV-2 into the NP-2/CD4 cells expressing APJ. The inhibitory efficiency has been found to be in the order of apelin-36>apelin-17>apelin-13>apelin-12.

More than 10 G protein-coupled receptors (GPCRs) have been shown to act as coreceptors for infection of human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIV). We have isolated HIV-1 variants infectious to primary brain-derived CD4-positive cells (BT-3 and BT-20/N) and U87/CD4 glioma cells that are resistant to T-cell line-tropic (T-tropic), macrophage-tropic (M-tropic), and T- and M-tropic (dualtropic) (X4, R5, and R5X4) HIV-1 strains. These primary brain-derived cells were also highly susceptible to HIV-2 ROD , HIV-2 SBL6669 , and SIV mndGB-1 . A factor or coreceptor that determines the susceptibility of these brain-derived cells to these HIV and SIV strains has not been fully identified. To identify this coreceptor, we examined amino acid sequences of all known HIV and SIV coreceptors and noticed that tyrosine residues are well conserved in their extracellular amino-terminal domains. By this criterion, we selected 18 GPCRs as candidates of coreceptors for HIV and SIV strains infectious to these brain-derived cells. mRNA expression of an orphan GPCR, RDC1, was detected in the brain-derived cells, the C8166 T-cell line, and peripheral blood lymphocytes, all of which are susceptible to HIV-1 variants, but not in macrophages, which are resistant to them. When a CD4-expressing cell line, NP-2/CD4, which shows strict resistance to infection not only with HIV-1 but also with HIV-2 or SIV, was transduced with the RDC1 gene, the cells became highly susceptible to HIV-2 and SIV mnd strains but to neither M- nor T-tropic HIV-1 strains. The cells also acquired a low susceptibility to the HIV-1 variants. These findings indicate that RDC1 is a novel coreceptor for several HIV-1, HIV-2, and SIV strains which infect brain-derived cells.

The purpose of this study was to determine whether contrast-enhanced sonography can be used to differentiate histopathologic grades of hepatocellular carcinoma.This study included 54 patients with hepatocellular carcinomas. All patients underwent fundamental and contrast-enhanced sonographic examinations. Auto-tracking contrast quantification software was used to determine the contrast arrival time, time to peak, peak intensity, contrast-enhanced time, wash-out time, enhancement slope, and clearance slope of the lesions. All lesions were confirmed by surgery. The hepatocellular carcinoma lesions were divided into 2 groups according to the World Health Organization grading system: group 1 (well-differentiated hepatocellular carcinomas) and group 2 (moderately to poorly differentiated carcinomas). The enhancement parameters between the groups were compared using a Student t test.Fourteen of 20 well-differentiated lesions showed a "fast-in, slow-out" enhancement pattern, whereas 6 showed a "fast-in, fast-out" pattern. Thirty-three of 34 moderately to poorly differentiated lesions showed a fast-in, fast-out pattern, whereas only 1 showed a fast-in, slow-out pattern. The differences in the time to peak, contrast-enhanced time, wash-out time, enhancement slope, and clearance slope between the groups were statistically significant (P.05), whereas the differences in the arrival time and peak intensity were not significant (P.05).The contrast patterns of well-differentiated and moderately to poorly differentiated hepatocellular carcinomas were quite different on contrast-enhanced sonography. The time to peak, contrast-enhanced time, and wash-out time of the well-differentiated hepatocellular carcinomas were longer than those of the moderately to poorly differentiated carcinomas, whereas the enhancement slope and clearance slope of the well-differentiated lesions were lower those that of the moderately to poorly differentiated lesions.

The role of the IRE1α-X-box-binding protein 1 (XBP1) pathway in the insulin-mediated hepatic lipogenic program and associated mechanisms were investigated in this study. We observed that phosphorylation of IRE1α (an upstream activator of XBP1) and splicing (activation) of XBP1 were elevated in the liver of the C57BL/6 mice with insulin resistance/hyperinsulinemia induced by high-fat diet. Treatment of nonobese diabetic mice with insulin activated hepatic XBP1. In cultured primary mouse hepatocytes, prolonged exposure to insulin induced IRE1α phosphorylation and XBP1 splicing significantly in the presence of insulin resistance. Overexpression of the activated XBP1 elevated the promoter activities of the sterol regulatory element-binding protein (SREBP)-1c and fatty acid synthase (FAS) genes. Knockdown of either the IRE1α or XBP1 gene by small interfering RNA prevented the insulin-stimulated promoter activities of both SREBP-1 and FAS genes. In investigating the associated mechanisms, we found a direct interaction between XBP1 and SREBP-1 promoter detected by the chromatin immunoprecipitation assays. Furthermore, the XBP1-mediated stimulation of the FAS promoter was eliminated by knocking down the SREBP-1c gene (Srebf1). Finally, we observed that insulin activation of the IRE1α-XBP1 pathway was prevented by inhibition of mammalian target of rapamycin-dependent protein synthesis. In conclusion, our results show that the IRE1α-XBP1-mediated unfolded protein response pathway is an integrated part of the insulin-induced hepatic lipogenic program and functions at an increased basal level in the presence of insulin resistance and hyperinsulinemia. Besides, the insulin-mediated protein synthesis is tightly connected with the insulin-mediated lipogenic program.

Autophagy is essential for maintaining both survival and health of cells. Autophagy is normally suppressed by amino acids and insulin. It is unclear what happens to the autophagy activity in the presence of insulin resistance and hyperinsulinemia. In this study, we examined the autophagy activity in the presence of insulin resistance and hyperinsulinemia and the associated mechanism. Insulin resistance and hyperinsulinemia were induced in mice by a high fat diet, followed by measurements of autophagy markers. Our results show that autophagy was suppressed in the livers of mice with insulin resistance and hyperinsulinemia. Transcript levels of some key autophagy genes were also suppressed in the presence of insulin resistance and hyperinsulinemia. Conversely, autophagy activity was increased in the livers of mice with streptozotocin-induced insulin deficiency. Levels of vps34, atg12, and gabarapl1 transcripts were elevated in the livers of mice with insulin deficiency. To study the mechanism, autophagy was induced by nutrient deprivation or glucagon in cultured hepatocytes in the presence or absence of insulin. Autophagy activity and transcript levels of vps34, atg12, and gabarapl1 genes were reduced by insulin. The effect of insulin was largely prevented by overexpression of the constitutive nuclear form of FoxO1. Importantly, autophagy of mitochondria (mitophagy) in cultured cells was suppressed by insulin in the presence of insulin resistance. Together, our results show that autophagy activity and expression of some key autophagy genes were suppressed in the presence of insulin resistance and hyperinsulinemia. Insulin suppression of autophagy involves FoxO1-mediated transcription of key autophagy genes.

In this study, we tested the hypothesis that human neutrophil α-defensins (HNPs) inhibit hepatic glucose production through a signaling pathway distinct from insulin. The effect of HNP-1 on fasting blood glucose levels and the expression of hepatic gluconeogenic genes was first examined. Using hyperinsulinemic-euglycemic clamps, we determined the effect of HNP-1 on endogenous glucose production, hepatic expression of key gluconeogenic genes and glucose uptake in skeletal muscle in Zucker diabetic fatty rats. In isolated primary hepatocytes, we studied the effect of HNP-1 and -2 on glucose production, expression of gluconeogenic genes, and phosphorylation of Akt, c-Src, and FoxO1. Our results show that HNP-1 reduced blood glucose levels of both normal mice and Zucker diabetic fatty rats predominantly through suppression of hepatic glucose production. HNPs inhibited glycogenolysis and gluconeogenesis in isolated hepatocytes. HNPs also suppressed expression of key gluconeogenic genes including phosphoenoylpyruvate carboxyl kinase and glucose-6-phosphatase. To investigate the mechanism, we found that HNPs stimulated phosphorylation of Akt and FoxO1 without activating IRS1. Nevertheless, HNPs activated c-Src. Blockade of c-Src activity with either a chemical inhibitor PP2 or an alternative inhibitor CSK prevented the inhibitory effect of HNPs on gluconeogenesis. Together, our results support the hypothesis that HNPs can suppress hepatic glucose production through an intracellular mechanism distinct from the classical insulin signaling pathway.

p38 mitogen-activated protein kinase (p38) is a member of MAP kinase family. Its wide-spectrum roles in the control of energy metabolism have been indicated in numerous studies. p38 participates in the energy metabolism in all major tissues/organs involved in the control of energy metabolism, including adipose tissue, skeletal muscles, islet cells, and liver. In white adipose tissue, p38 plays an important role in adipose differentiation and glucose uptake although it is still inconclusive whether this role of p38 is stimulatory or inhibitory. The stimulatory role of p38 in transcription of the uncoupling protein 1 (UCP1) gene in brown adipose tissue is relatively clear. A fundamental role for p38 in the differentiation of skeletal muscles and mitochondrial biogenesis in skeletal muscles is rather definitive although the role of p38 in glucose uptake of skeletal muscles remains controversial. In islet cells, p38 appears to be involved in beta-cell apoptosis. p38 has been indicated in the control of preproinsulin gene transcription, but remains controversial. However, it seems clear that p38 does not play a significant role in insulin secretion. In the liver, p38 plays a central role in hepatic glucose and lipid metabolism. Activation of p38 participates in the processes to increase blood glucose levels through reducing glycogen synthesis and increasing hepatic gluconeogenesis. p38 appears to prevent fat storage by inhibiting hepatic lipogenesis and promoting fatty acid oxidation in the liver. Additionally, p38 may play a critical role in cholesterol metabolism by regulating expression of the LDLR gene and bile metabolism. p38 does not only participate in various physiological and pathophysiological processes in cardiomyocytes, but also is heavily involved in the development of atherosclerotic lessions through its influences on monocytes/macrophages, vascular endothelial cells, and vascular smooth muscle cells.

Twelve G protein-coupled receptors, including chemokine receptors, act as coreceptors and determinants for the cell tropisms of human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIV). We isolated HIV-1 variants from T-cell-line (T)- and macrophage (M)-tropic (i.e., dualtropic) (R5-R3-X4) HIV-1 strains and also produced six HIV-1 mutants carrying single-point amino acid substitutions at the tip of the V3 region of the Env protein of HIV-1. These variants and three mutants infected brain-derived CD4-positive cells that are resistant to M-, T-, or dualtropic (R5, X4, or R5-X4) HIV-1 strains. However, a factor that determines this cell tropism has not been identified. This study shows that primary brain-derived fibroblast-like cell strains, BT-3 and BT-20/N, as well as a CD4-transduced glioma cell line, U87/CD4, which were susceptible to these HIV-1 variants and mutants and the HIV-2 ROD strain, expressed mRNA of an orphan G protein-coupled receptor (GPCR), GPR1. When a CD4-positive cell line which was strictly resistant to infection with diverse HIV-1 and HIV-2 strains was transduced with GPR1, the cell line became susceptible to these HIV-1 variants and mutants and to an HIV-2 strain but not to T- or dualtropic HIV-1 strains, and numerous syncytia formed after infection. These results indicate that GPR1 functions as a coreceptor for the HIV-1 variants and mutants and for the HIV-2 ROD strain in vitro.

Tryptase TL2 purified from MOLT-4 human T cells binds to the envelope protein of human immunodeficiency virus type 1 (HIV 1). Tryptase TL2 and CD26 antigen are supposed to play roles in HIV-1 entry into cells. Although CD4 is a principal receptor for HIV-1, brain cells expressing the CD4 antigen are not permissive to HIV-1 strains infectious to monocyte or T-cell lines. We examined whether the non-permissiveness of the brain-derived cells to standard HIV-1 strains could be explained by a lack of tryptase TL2 or CD26. Western blots showed that the amounts of tryptase TL2 expressed in cell lysates prepared from the brain-derived cells were similar to those prepared from various cells susceptible to HIV-1 strains. Furthermore, flow cytometry revealed the presence of the CD26 antigen on the cell surface of many types of cells. The resistance of the brain-derived cells to standard HIV-1 strains is not due to a lack of tryptase TL2 or CD26.