Lipase (EC3.1.1.3) from Candida sp. 99-125 was immobilized on chitosan by chemical covalence. Lipase was first immobilized to chitosan beads by activating its hydroxyl groups with carbodiimide followed by cross-linking more lipase to the amino groups with glutaraldehyde. In this article, different factors that influenced the immobilization were investigated, and the optimum conditions were ascertained. Comparative studies of organic solvent and thermal stability between free lipase and immobilized lipase were conducted. Immobilization enhanced the lipase stability against changes of temperature and organic solvent. Immobilization lipase can be reused in the synthesis system of palmitate hexadecyl. Operational stability tests indicated that the immobilized lipase occurs after 16 consecutive batches, the conversion rate remained 85%. Such results revealed good potential for recycling under esterification system.
Candida ; enzymology ; Carbodiimides ; chemistry ; Chitosan ; chemistry ; Cross-Linking Reagents ; Enzyme Stability ; Enzymes, Immobilized ; Lipase ; metabolism ; Palmitates ; chemistry

Ischemia and reperfusion (I/R) injury is a major cause of hepatic failure after liver surgery, but no method could monitor or predict it real-time during surgery. We measured bioelectrical impedance (BEI) and cell viability to assess the usefulness of BEI during I/R in rat liver. A 70% partial liver ischemia model was used. BEI was measured at various frequencies. Adenosine triphosphate (ATP) content, and palmitic acid oxidation rate were measured, and histological changes were observed in order to quantify liver cell viability. BEI changed significantly during ischemia at low frequency. In the ischemia group, BEI increased gradually during 60 min of ischemia and had a tendency to plateau thereafter. The ATP content decreased below 20% of the baseline level. In the I/R group, BEI recovered to near baseline level. After 24 hr of reperfusion, the ATP contents decreased to below 50% in 30, 60 and 120 min of ischemia and the palmitic acid metabolic rates decreased to 91%, 78%, and 74%, respectively, compared with normal liver. BEI may be a good tool for monitoring I/R during liver surgery. The liver is relatively tolerant to ischemia, however after reperfusion, liver cells may be damaged depending upon the duration of ischemia.
Adenosine Triphosphate/metabolism ; Animals ; *Cell Survival ; Electric Impedance ; Energy Metabolism ; Ischemia/*metabolism ; Liver/*metabolism/pathology ; Male ; Palmitates/metabolism ; Rats ; Rats, Sprague-Dawley ; *Reperfusion ; Reperfusion Injury/metabolism/pathology

AIMTo prepare amylopectin anchored dipyridamole (DIP) liposome and to study its tissue distribution in mice.

METHODSThe regular DIP liposomes were prepared by film-scatter method. The amphiphilic O-palmitoyl amylopectin was synthesized and added to modify the surface of liposome. The entrapping efficiency, zeta potential, mean diameter, span of modified and regular liposomes were assayed. The RP-HPLC was used for the determination of DIP concentration in mice tissue.

RESULTSAfter modification, the entrapping efficiency depressed, zeta potential was raised, mean diameter and span had no obvious change. The level of DIP in lung, liver and spleen for regular liposomes were higher than that of injections. Compared with regular liposomes, the modified liposomes increased the DIP level in lung, and decreased the DIP level in liver, spleen, moreover, lengthened the retention time of DIP in lung.

CONCLUSIONThe distribution of modified liposome in mice was markedly changed as compared with regular liposomes and injections. The modified liposomes had obvious lung targeting property.

Amylopectin ; analogs & derivatives ; chemistry ; Animals ; Area Under Curve ; Dipyridamole ; administration & dosage ; chemistry ; pharmacokinetics ; Drug Delivery Systems ; Liposomes ; Lung ; metabolism ; Male ; Mice ; Palmitates ; chemistry ; Particle Size ; Tissue Distribution

BACKGROUND: Pancreatic β-cells elevate insulin production and secretion through a compensatory mechanism to override insulin resistance under metabolic stress conditions. Deficits in β-cell compensatory capacity result in hyperglycemia and type 2 diabetes (T2D). However, the mechanism in the regulation of β-cell compensative capacity remains elusive. Nuclear factor-Y (NF-Y) is critical for pancreatic islets' homeostasis under physiological conditions, but its role in β-cell compensatory response to insulin resistance in obesity is unclear. METHODS: In this study, using obese ( ob/ob ) mice with an absence of NF-Y subunit A (NF-YA) in β-cells ( ob , Nf-ya βKO) as well as rat insulinoma cell line (INS1)-based models, we determined whether NF-Y-mediated apoptosis makes an essential contribution to β-cell compensation upon metabolic stress. RESULTS: Obese animals had markedly augmented NF-Y expression in pancreatic islets. Deletion of β-cell Nf-ya in obese mice worsened glucose intolerance and resulted in β-cell dysfunction, which was attributable to augmented β-cell apoptosis and reactive oxygen species (ROS). Furthermore, primary pancreatic islets from Nf-ya βKO mice were sensitive to palmitate-induced β-cell apoptosis due to mitochondrial impairment and the attenuated antioxidant response, which resulted in the aggravation of phosphorylated c-Jun N-terminal kinase (JNK) and cleaved caspase-3. These detrimental effects were completely relieved by ROS scavenger. Ultimately, forced overexpression of NF-Y in INS1 β-cell line could rescue palmitate-induced β-cell apoptosis, dysfunction, and mitochondrial impairment. CONCLUSION Pancreatic NF-Y might be an essential regulator of β-cell compensation under metabolic stress.
Rats ; Mice ; Animals ; Reactive Oxygen Species/metabolism* ; Diabetes Mellitus, Type 2/metabolism* ; Insulin Resistance ; Insulin ; Insulin-Secreting Cells/metabolism* ; Apoptosis ; Stress, Physiological ; Transcription Factors/metabolism* ; Palmitates/pharmacology* ; Obesity/metabolism*

Heterotrimeric guanine nucleotide binding regulatory proteins (G proteins) transduce extracellular signals into intracellular signals by coupling receptors and effectors. Because most of the G protein-coupled receptors are integral proteins, the G proteins need to have a membrane binding capacity to receive signals from the receptors. The alpha subunit of G protein binds tightly to the cytoplasmic face of the plasma membrane without any membrane spanning domain. Fatty acylation of G alpha with myristic acid or palmitic acid, in addition to the beta gamma subunits, plays an important role in anchoring the G alpha subunit. The reversible and dynamic palmitoylation of the alpha subunit of stimulatory G protein (Gs alpha) has been suggested as essential for its membrane attachment. However, in our previous experiments, Gs alpha deleted in the amino terminus containing palmitoylation site, retained its binding capacity when expressed in COS cells. Thus, to evaluate the role of palmitoylation in Gs alpha membrane binding, we constructed and expressed non-palmitoylated mutants of Gs alpha and analyzed their subcellular distributions in COS-1 cells. We found that non-palmitoylated mutants of Gs alpha, C3S- and G2A/C3S Gs alpha, retained their membrane binding capacities in COS-1 cells, demonstrating that palmitoylation is not essential for membrane binding of Gs alpha in COS-1 cells. We also found that the palmitoylation did not change significantly the distribution of Gs alpha in Triton X-114 partition. These results suggest that the palmitoylation of Gs alpha may produce different effects on membrane binding depending on cell types.
Animal ; Blotting, Western ; COS Cells ; Cell Membrane/metabolism ; Detergents/pharmacology ; G-Protein, Stimulatory Gs/metabolism* ; G-Protein, Stimulatory Gs/genetics ; Immunoblotting ; Isoproterenol/metabolism ; Mutagenesis ; Palmitates/metabolism* ; Polyethylene Glycols/pharmacology ; Rats ; Transfection

BACKGROUNDGlucolipotoxicity might play an important role in the β cell decompensation stage during the development of obesity-associated type 2 diabetes. Tissue inhibitor of metalloproteinase-1 (TIMP-1) inhibits matrix metalloproteinase (MMP) activity and regulates proliferation and apoptosis of a variety of cell types, including pancreatic β-cells. In the present study, we investigated whether TIMP-1 counteracts glucolipotoxicity in the pancreatic β-cell line INS-1.

METHODSINS-1 cells were incubated in normal or high glucose, with or without palmitate (0.4 mmol/L), in the presence of TIMP-1 or MMP inhibitor GM60001. In some experiments, cells were pretreated with phosphatidylinositol-3 (PI-3) kinase inhibitor, LY294002 or wortmannin. The amount of dead INS-1 cells was determined by HO342 and propidium iodide staining. Akt phosphorylation was evaluated by Western blotting analysis to investigate a possible mechanism of TIMP-1's action.

RESULTSTIMP-1 protected INS-1 cells from glucolipotoxicity independent of MMP inhibition. TIMP-1 stimulated Akt phosphorylation. Inhibition of the PI-3 kinase pathway abolished the survival effect of TIMP-1.

CONCLUSIONTIMP-1 may counteract glucolipotoxicity induced β-cell death via a PI-3 kinase pathway.

Animals ; Cell Line ; Glucose ; pharmacology ; Insulin-Secreting Cells ; drug effects ; metabolism ; Palmitates ; pharmacology ; Phosphatidylinositol 3-Kinases ; Phosphorylation ; drug effects ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Signal Transduction ; Tissue Inhibitor of Metalloproteinase-1 ; pharmacology

The saturated free fatty acid (FFA), palmitate, could induce apoptosis in various cell types, but little is known about its effects on human umbilical cord-derived mesenchymal stem cells (hUC-MSCs). Here, we investigated whether palmitate induced apoptosis and endoplasmic reticulum (ER) stress in hUC-MSCs. hUC-MSCs were stained by labeled antibodies and identified by flow cytometry. After administration with palmitate, apoptotic cell was assessed by flow cytometry using the Annexin V-FITC/7-AAD apoptosis detection kit. Relative spliced XBP1 levels were analyzed using semi-quantitative RT-PCR. The mRNA of BiP, GRP94, ATF4 and CHOP were analyzed by real-time PCR. Relative BiP and CHOP protein were analyzed using Western blot analysis. The results showed that hUC-MSCs were homogeneously positive for MSC markers; palmitate increased apoptosis of hUC-MSCs and activated XBP1 splicing, BiP, GRP94, ATF4 and CHOP transcription. These findings suggest that palmitate induces apoptosis and ER stress in hUC-MSCs.
Activating Transcription Factor 4 ; metabolism ; Apoptosis ; DNA-Binding Proteins ; metabolism ; Endoplasmic Reticulum Stress ; Heat-Shock Proteins ; metabolism ; Humans ; Membrane Glycoproteins ; metabolism ; Mesenchymal Stromal Cells ; cytology ; drug effects ; Palmitates ; pharmacology ; Regulatory Factor X Transcription Factors ; Transcription Factor CHOP ; metabolism ; Transcription Factors ; metabolism ; Umbilical Cord ; cytology ; X-Box Binding Protein 1

OBJECTIVETo study the effect of palmitate on toll-like receptor 4 (TLR4) expression and signaling in vascular endothelial cells.

METHODSPig iliac endothelial cells (PIECs) were incubated with palmitate. TLR4 gene expression levels were measured by quantitative real-time PCR, and TLR4 and IκBα protein expressions by Western blotting. The expression levels of TLR4 protein on the surface of PIECs were quantified using flow cytometry. ELISA was employed to detect tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) concentrations in the cell medium.

RESULTSPalmitate treatment significantly increased TLR4 mRNA and protein expression levels in PIECs compared with those in the control cells (4.73∓0.61 vs 1.25∓0.90, P<0.05; 5.79∓0.05 vs 4.07∓0.31, P<0.05). The expression levels of TLR4 on the cell surface significantly increased (38.070∓3.907 vs 29.390∓1.072, P<0.05), while IκBα protein level was significantly lowered in PIECs after palmitate treatment as compared with those in the control cells (2.04∓0.22 vs 3.98∓0.18, P<0.05). Palmitate treatment significantly elevated TNF-α (2.52∓0.30 vs 1.38∓0.26, P<0.05) and IL-6 (IL-6: 3.28∓0.32 vs 1.44∓0.28, P<0.05) concentrations in the cell culture medium.

CONCLUSIONPalmitate can enhance TLR4 expression and signaling in porcine vascular endothelial cells.

Animals ; Blotting, Western ; Endothelial Cells ; drug effects ; metabolism ; I-kappa B Proteins ; metabolism ; Interleukin-6 ; metabolism ; NF-KappaB Inhibitor alpha ; Palmitates ; pharmacology ; RNA, Messenger ; Real-Time Polymerase Chain Reaction ; Signal Transduction ; Swine ; Toll-Like Receptor 4 ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo investigate the attenuating effect of curcumin, an anti-inflammatory compound derived from dietary spice turmeric (Curcuma longa) on the pro-inflammatory insulin-resistant state in 3T3-L1 adipocytes.

METHODSGlucose uptake rate was determined with the [3H] 2-deoxyglucose uptake method. Expressions of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured by quantitative RT-PCR analysis and ELISA. Nuclear transcription factor kappaB p65 (NF-kappa p65) and mitogen-activated protein kinase (MAPKs) were detected by Western blot assay.

RESULTSThe basal glucose uptake was not altered, and curcumin increased the insulin-stimulated glucose uptake in 3T3-L1 cells. Curcumin suppressed the transcription and secretion of TNF-alpha and IL-6 induced by palmitate in a concentration-dependent manner. Palmitate induced nuclear translocation of NF-kappaB. The activities of Jun NH2-terminal kinase (JNK), extracellular signal-regulated kinase1/2 (ERK1/2) and p38MAPK decreased in the presence of curcumin. Moreover, pretreatment with SP600125 (inhibitor of JNK) instead of PD98059 or SB203580 (inhibitor of ERK1/2 or p38MAPK, respectively) decreased the up-regulation of TNF-alpha induced by palmitate.

CONCLUSIONCurcumin reverses palmitate-induced insulin resistance state in 3T3-L1 adipocytes through the NF-kappaB and JNK pathway.

3T3-L1 Cells ; Animals ; Anthracenes ; pharmacology ; Anti-Inflammatory Agents, Non-Steroidal ; pharmacology ; Curcumin ; pharmacology ; Glucose ; metabolism ; Insulin ; pharmacology ; Insulin Resistance ; Interleukin-6 ; genetics ; metabolism ; JNK Mitogen-Activated Protein Kinases ; metabolism ; MAP Kinase Signaling System ; Mice ; NF-kappa B ; metabolism ; Palmitates ; pharmacology ; Protein Kinase Inhibitors ; pharmacology ; Tumor Necrosis Factor-alpha ; genetics ; metabolism ; Up-Regulation

Hepatocytes act as a reservoir for the human immunodeficiency viruses (HIV) and are responsible for its continual dissemination in the peripheral circulation. For this reason, galactosylated liposomes (GalLs) containing home-made [(2-lactoylamido) ethylamino] formic acid cholesterol ester (CH-ED-LA ) as a homing device were prepared to study the biodistribution of the liposomal azidothymidine palmitate (AZTP) in mice. Four liposomes of the present study, soybean phosphatidylcholine (SPC)/cholesterol(CH)/CH-ED-LA (80 : 10: 10, 10% GalLs), SPC/CH/CH-ED-LA (80 : 15:5, 5% GalLs), SPC/CH/CH-ED-LA (80 : 17 : 3, 3% GallLs) and SPC/CH (80 : 20, CL) incorporated AZTP were prepared by ethanol-injection method followed by ultrasonic-dispersion and characterized by entrapped efficiency which was more than 95% and their mean diameter was less than 100 nm, respectively. The effects of the addition upon the liposomal membrane potential and AZTP content were also unseen. The distributions of AZT in various organs were determinated by reversed phase HPLC after intravenous administration via tail vein in mice, at a dose of 15.85 mg x kg(-1) AZT solution and 30 mg x kg(-1) AZTP (at equimolar doses) in CL or GalLs, respectively. Compared to AZT control solution, the half-life of AZT in each group of AZTP liposomes increased significantly (P < 0.05). In addition, the concentration-averaged overall drug targeting efficiency (r(e)) of the liver presented by AZTP CL and GalLs containing 3% , 5% , 10% (mol/mol) CH-ED-LA increased 1.32 and 1.48, 2.13, 1.50 times as that of AZT solution, respectively. These results indicate that liposomes containing such novel galactosylated lipid, CH-ED-LA, had remarkably improved the targetability of AZTP to liver, and are anticipated to be a potential candidate for liver targeting delivery carriers.
Animals ; Anti-HIV Agents ; administration & dosage ; pharmacokinetics ; Cholesterol ; analogs & derivatives ; chemistry ; Drug Carriers ; Drug Compounding ; Drug Delivery Systems ; Female ; Injections, Intravenous ; Liposomes ; chemistry ; Liver ; metabolism ; Male ; Mice ; Palmitates ; administration & dosage ; pharmacokinetics ; Particle Size ; Random Allocation ; Tissue Distribution ; Zidovudine ; administration & dosage ; pharmacokinetics