Extended-release niacin/laropiprant lipid-altering consistency across patient subgroups

BACKGROUND

In patients with primary hypercholesterolemia or mixed dyslipidemia, extended-release niacin/laropiprant (ERN/LRPT) improves key lipid parameters associated with increased atherosclerotic coronary heart disease (CHD) risk.

AIM

This analysis examined data from four Phase III, randomised, double-blind trials to determine the consistency of ERN/LRPT's lipid-altering efficacy among subgroups of patients.

METHODS

Data from four Phase III, randomised, double-blind trials of ERN/LRPT were analysed to determine the consistency of ERN/LRPT's lipid-altering efficacy among subgroups of gender, race (white, non-white), region (US, ex-US), baseline age (<65, ≥65 years), use of statin therapy, CHD risk status (low, multiple, high) and type of hyperlipidemia (primary hypercholesterolemia, mixed dyslipidemia), as well as across baseline low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) levels. End-points included the per cent change from baseline in LDL-C, HDL-C and TG levels. Consistency of the treatment effects on LDL-C, HDL-C and TG across subgroups was evaluated by examining treatment difference estimates with 95% confidence intervals.

RESULTS

  Treatment with ERN/LRPT significantly improved LDL-C, HDL-C and TG levels compared with placebo/active comparator in each study cohort. These effects were generally consistent across all examined subgroups.

CONCLUSION

Extended-release niacin/laropiprant represents an effective therapeutic option for the treatment of dyslipidemia across a range of patient types.

Bisphosphonates induce senescence in normal human oral keratinocytes

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) commonly occurs in individuals receiving bisphosphonates (BPs) with clinical manifestations of the exposed necrotic bone. Although defective wound healing of soft tissue is frequently, if not always, observed in BRONJ, the effects of BPs on oral soft tissue or cells remain unknown. To investigate the effects of BPs on cells of oral mucosal tissue, we studied the effect of pamidronate (PAM), one of the BPs most commonly administered to cancer patients, on the phenotypes of normal human oral keratinocytes (NHOK) and fibroblasts (NHOF). When exposed to PAM at 10 µM, NHOK, not NHOF, underwent senescence: NHOK overexpressed senescence-associated β-galactosidase (SA-β-Gal), p16INK4A, IL-6, and IL-8. When exposed to a higher level (50 µM) of PAM, NHOK maintained senescent phenotypes, but NHOF underwent apoptosis. PAM-induced senescence in NHOK is mediated, in part, via geranylgeranylation of the mevalonate pathway. Our in vitro 3D oral mucosal tissue construction studies further demonstrated that PAM induced senescence and impaired re-epithelialization of oral mucosa. Analysis of these data indicates that premature senescence of oral mucosal cells and subsequent defective soft-tissue wound healing might be partly responsible for the development of BRONJ in individuals receiving PAM or other BPs.

Optimization of handling and refrigerated storage of guppy Poecilia reticulata sperm

Sperm collection methods and the effect of osmolality, ions, sugar, temperature, pH and dilution ratio on sperm motility were investigated in guppies Poecilia reticulata. The present study revealed that the sperm was motile in a wide range of osmolalities (200-470 mOsm kg(-1)) either in Hanks balanced-salt solution (HBSS) or in non-electrolyte solutions such as glucose or sucrose. Sperm collected from crushing testes yielded lower motility and shorter motility duration than samples collected without crushing but gentle disruption. Dilution ratios within the range of 1:50 to 1:500 of sperm to HBSS had minimal effect on sperm motility during extended refrigerated storage. Examination of storage temperature showed that refrigerated storage at 4 degrees C was superior to room temperature (25 degrees C). Sperm was found to tolerate a wide range of pH from 5.6 to 7.8, but motility was affected negatively by pH values >7.8.

Investigation of porcine endogenous retrovirus in the conservation population of Ningxiang pig

Porcine endogenous retrovirus (PERV) varies between pig breeds. Screening and analysis of PERV in putative pig breeds may provide basic parameters to evaluate the biological safety of xenotransplantation from pigs to humans. In this study, PERV was investigated among the conservation population of the Ningxiang pig. The result revealed that the genotype of PERV distribution was subtype A, 100%; subtype B, 100%; and subtype C, 100%. The env sequences of PERV-A and -B showed 11 clones detected by KpnI and MboI digestion, indicating that there existed multiple variants of PERV-A and -B in the Ningxiang pig. Reverse transcriptase polymerase chain reaction results showed that PERV had transcriptional activity in these individuals. In addition, PERV A/C recombinant was detected in most individuals of Ningxiang pig. Because PERV A/C recombinants increase the potential infectious risk, the breed may not be a proper donor for xenotransplantation.

Oxidative Stress and Apoptosis of Human Brain Microvascular Endothelial Cells Induced by Free Fatty Acids

Damage to endothelial cells is a key event in the pathogenesis of atherosclerosis and vascular disease. This study aimed to determine whether free fatty acids (FFAs) induced oxidative stress and apoptosis in human brain microvascular endothelial cells (HBMVECs) in vitro and, if so, which signalling pathway mediated these effects. After culture in different concentrations of FFAs for 24-72 h, cell viability/proliferation was determined using a cell counting kit, apoptosis was detected by measuring caspase-3 activity and by using annexin V-conjugated fluorescein isothiocyanate/propidium iodide staining, and oxidative stress was evaluated by measuring the levels of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). The HBMVECs exposed to FFAs showed significantly decreased cell proliferation, increased apoptosis and ROS levels, and decreased MMP. In conclusion, the results showed that high levels of FFAs induced oxidative stress, which damaged HBMVECs and resulted in apoptosis.

Hepatocyte inflammation model for cytotoxicity research: fructose or glycolaldehyde as a source of endogenous toxins

Insulin resistance and hepatotoxicity induced in high fructose fed rats may involve fructose derived endogenous toxins formed by inflammation. Thus fructose was seventy-fold more toxic if hepatocytes were exposed to non-toxic levels of hydrogen peroxide (H(2)O(2)) released by inflammatory cells. This was prevented by iron (Fe) chelators, hydroxyl radical scavengers, and increased by Fe, copper (Cu) or catalase inhibition. Fructose or glyceraldehyde/dihydroxyacetone metabolites were oxidized by Fenton radicals to glyoxal. Glyoxal (15 microM) cytotoxicity was increased about 200-fold by H(2)O(2). Glycolaldehyde was enzymically formed from glyceraldehyde, the fructokinase/aldolase B product of fructose. Glycolaldehyde cytotoxicity was increased 20-fold by H(2)O(2). The oxidative stress cytotoxicity induced was attributed to the Fenton oxidation of glycolaldehyde forming glycolaldehyde radicals and glyoxal, since cytotoxicity was prevented by aminoguanidine (glyoxal trap) or Fenton inhibitors. Glyoxal was also the Fenton product responsible for glycolaldehyde protein carbonylation as carbonylation was prevented by aminoguanidine or Fenton inhibitors.

Over-expression of SOCS-3 gene promotes IL-10 production by JEG-3 trophoblast cells

Suppressor of cytokine signaling-3 (SOCS-3) plays an important role in negative regulation of inflammatory response. Evidence has shown that SOCS-3 and IL-10 expressions were significantly reduced in placental trophoblasts from preeclampsia. IL-10 is an anti-inflammatory cytokine. In this study, we sought to determine if enhance SOCS-3 expression could affect IL-10 production in placental trophoblasts. Placental JEG-3 cells were used. Over-expression of SOCS-3 was generated by transfection of JEG-3 cells with a green fluorescent protein (GFP) tagged SOCS-3 gene, SOCS-3/ZsGreen1, by siPORT lipid transfection. Cells transfected with ZsGreen1 vector only was used as control. Our results showed that IL-6 production was reduced in cells over-expressed with SOCS-3. Moreover, SOCS-3 transfected cells produced more IL-10 when stimulated with IL-6. The increased IL-10 production by JEG-3 cells was in a dose-dependent manner, p<0.05. Our data suggested that enhanced SOCS-3 gene expression could promote IL-10 production by placental trophoblast cells, suggesting that SOCS-3 may play an important role in regulation of cytokine induced anti-inflammatory response in placental trophoblasts.

Altered interleukin-6 receptor, IL-6R and gp130, production and expression and decreased SOCS-3 expression in placentas from women with pre-eclampsia

Interleukin-6 (IL-6) and its receptor complex, IL-6 receptor (IL-6R) and gp130, are critical in induction of suppressor of cytokine signalling-3 (SOCS-3) protein, a negative cytokine regulator and anti-inflammatory mediator, in a biological system. Increased inflammatory response is believed to contribute to the placental dysfunction in pre-eclampsia (PE). However, it is not known if altered IL-6 receptor signalling and decreased SOCS-3 expression occur in placentas from PE. To study this, we examined IL-6, soluble IL-6R (sIL-6R) and soluble gp130 (sgp130) production by villous tissue from normal and PE placentas. Hypoxia effects on IL-6, sIL-6R and sgp130 production was determined. IL-6R, gp130 and SOCS-3 expression were determined by immunohistochemical staining and by Western blot. Our results showed that under normoxic conditions (21% O(2)), villous tissue from PE placentas produced relative more sgp130, but significantly less IL-6 and sIL-6R (p<0.01) than normal placental tissue. The ratio of sgp130/sIL-6R release was significantly higher by PE placentas than normal placentas, p<0.01. Under hypoxic conditions (2% O(2)), IL-6 production was significantly reduced by both normal (p<0.01) and PE (p<0.05) placental tissue. Hypoxia promoted sgp130 release by normal, but not by PE, placental tissue. Reduced IL-6R and SOCS-3 immunostaining and expression were found in PE placentas. We concluded that increased ratio of sgp130/sIL-6R production and/or reduced sIL-6R production combined with down-regulation of IL-6R and SOCS-3 expression in trophoblasts may lead to less cytokine inhibitory activity in PE placentas, which may account for the increased placental inflammatory response in PE.

Fructose and carbonyl metabolites as endogenous toxins

Dietary fructose consumption is one of the environmental factors contributing to the development of obesity and a fatty liver (hepatic steatosis). A two-hit hypothesis has been proposed for progression of hepatic steatosis to the more serious non-alcoholic steatosis (NASH), with the first hit being hepatic steatosis, and the second hit being inflammation and associated oxidative stress caused by reactive oxygen species (ROS) formation. As well, fructose-fed rats develop insulin resistance and serum levels of methylglyoxal, a glycolytic metabolite, are increased. Previously we reported that glyoxal-induced hepatocyte cytotoxicity could be attributed to mitochondrial toxicity as mitochondrial membrane potential was decreased and cytotoxicity was increased several orders of magnitude by low non-cytotoxic doses of H(2)O(2) (hepatocyte inflammation model). In this study, we have assessed the toxicity of fructose towards hepatocytes and investigated the molecular cytotoxic mechanisms involved. Fructose itself was only toxic at 1.5M, whereas 12 mM caused 50% cell death in 2h if the hepatocytes were exposed to a non-cytotoxic dose of H(2)O(2) continuously generated by glucose and glucose oxidase. The cytotoxic mechanism involved oxidative stress as ROS and H(2)O(2) formation preceded cytotoxicity, and cytotoxicity was prevented by radical scavengers, lipid antioxidants and ROS scavengers. It is proposed that the highly potent Fenton derived ROS catalyse the oxidation of fructose and particularly its carbonyl metabolites glycolaldehyde, dihydroxyacetone, glyceraldehyde. The carbon radicals and glyoxal formed compromise the cell's resistance to H(2)O(2).