bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolation at physiological temperature of detergent-resistant membranes with properties expected of lipid rafts: the influence of buffer composition
Authors: Chen Xi , Jen Angela , Warley Alice , Lawrence M. Jayne , Quinn Peter J. , Morris Roger J. 
Published: October 2008

The failure of most non-ionic detergents to release patches of DRM (detergent-resistant membrane) at 37 °C undermines the claim that DRMs consist of lipid nanodomains that exist in an Lo (liquid ordered) phase on the living cell surface. In the present study, we have shown that inclusion of cations (Mg2+, K+) to mimic the intracellular environment stabilizes membranes during solubilization sufficiently to allow the isolation of DRMs at 37 °C, using either Triton X-100 or Brij 96. These DRMs are sensitive to chelation of cholesterol, maintain outside-out orientation of membrane glycoproteins, have prolonged (18 h) stability at 37 °C, and are vesicles or sheets up to 150–200 nm diameter. DRMs containing GPI (glycosylphosphatidylinositol)-anchored proteins PrP (prion protein) and Thy-1 can be separated by immunoaffinity isolation, in keeping with their separate organization and trafficking on the neuronal surface. Thy-1, but not PrP, DRMs are associated with actin. EM (electron microscopy) immunohistochemistry shows most PrP, and some Thy-1, to be clustered on DRMs, again maintaining their organization on the neuronal surface. For DRMs labelled for either protein, the bulk of the surface of the DRM is not labelled, indicating that the GPI-anchored protein is a minor component of its lipid domain. These 37 °C DRMs thus have properties expected of raft membrane, yet pose more questions about how proteins are organized within these nanodomains.
Oleoyl-oestrone inhibits lipogenic, but maintains thermogenic, gene expression of brown adipose tissue in overweight rats
Authors: Romero María del Mar , Fernández-López José A. , Esteve Montserrat , Alemany Marià 
Published: October 2008

In the present study we intended to determine how BAT (brown adipose tissue) maintained thermogenesis under treatment with OE (oleoyl-oestrone), a powerful slimming hormone that sheds off body lipid but maintains the metabolic rate. Overweight male rats were subjected to daily gavages of 10 nmol/g of OE or vehicle (control) for 10 days. A PF (pair-fed) vehicle-receiving group was used to discount the effects attributable to energy availability limitation. Interscapular BAT mass, lipid, DNA, mRNA and the RT-PCR (real-time PCR) expression of lipid and energy metabolism genes for enzymes and regulatory proteins were measured. BAT mass and lipid were decreased in OE and PF, with the latter showing a marked reduction in tissue mRNA. Maintenance of perilipin gene expression in PF and OE rats despite the loss of lipid suggests the preservation of the vacuolar interactive surface, a critical factor for thermogenic responsiveness. OE and, to a lesser extent, PF maintained the expression of genes controlling lipolysis and fatty acid oxidation, but markedly decreased the expression of those genes involved in lipogenic and acyl-glycerol synthesis. OE did not affect UCP1 (uncoupling protein 1) (decreased in PF), β3 adrenergic receptors or hormone-sensitive lipase gene mRNAs, which may translate in maintaining a full thermogenic system potential. OE rats were able to maintain a less energetically stressed BAT (probably through glucose utilization) than PF rats. These changes were not paralleled in PF rats, in which lower thermogenesis and glucose preservation resulted in a heavier toll on internal fat stores. Thus the mechanism of action of OE is more complex and tissue-specific than previously assumed.
Life, death and burial: multifaceted impact of autophagy
Authors: Galluzzi Lorenzo , Morselli Eugenia , Vicencio José Miguel , Kepp Oliver , Joza Nicholas , Tajeddine Nicolas , Kroemer Guido 
Published: October 2008

Macroautophagy, often referred to as autophagy, designates the process by which portions of the cytoplasm, intracellular organelles and long-lived proteins are engulfed in double-membraned vacuoles (autophagosomes) and sent for lysosomal degradation. Basal levels of autophagy contribute to the maintenance of intracellular homoeostasis by ensuring the turnover of supernumerary, aged and/or damaged components. Under conditions of starvation, the autophagic pathway operates to supply cells with metabolic substrates, and hence represents an important pro-survival mechanism. Moreover, autophagy is required for normal development and for the protective response to intracellular pathogens. Conversely, uncontrolled autophagy is associated with a particular type of cell death (termed autophagic, or type II) that is characterized by the massive accumulation of autophagosomes. Regulators of apoptosis (e.g. Bcl-2 family members) also modulate autophagy, suggesting an intimate cross-talk between these two degradative pathways. It is still unclear whether autophagic vacuolization has a causative role in cell death or whether it represents the ultimate attempt of cells to cope with lethal stress. For a multicellular organism, autophagic cell death might well represent a pro-survival mechanism, by providing metabolic supplies during whole-body nutrient deprivation. Alternatively, type II cell death might contribute to the disposal of cell corpses when heterophagy is deficient. Here, we briefly review the roles of autophagy in cell death and its avoidance.
Glucolipotoxicity of the pancreatic β-cell: myth or reality?
Authors: Poitout Vincent 
Published: October 2008

The glucolipotoxicity hypothesis postulates that chronically elevated levels of glucose and fatty acids adversely affect pancreatic β-cell function and thereby contribute to the deterioration of insulin secretion in Type 2 diabetes. Whereas ample experimental evidence in in vitro systems supports the glucolipotoxicity hypothesis, the contribution of this phenomenon to β-cell dysfunction in human Type 2 diabetes has been questioned. The reasons for this controversy include: differences between in vitro systems and in vivo situations; time-dependent effects of fatty acids on insulin secretion (acutely stimulatory and chronically inhibitory); and the ill-defined use of the suffix ‘-toxicity’. In vitro, prolonged exposure of insulin-secreting cells or isolated islets to concomitantly elevated levels of fatty acids and glucose impairs insulin secretion, inhibits insulin gene expression and, under certain circumstances, induces β-cell death by apoptosis. Recent studies in our laboratory have shown that cyclical and alternate infusions of glucose and Intralipid in rats impair insulin gene expression, providing evidence that inhibition of the insulin gene under glucolipotoxic conditions is an early defect that might indeed contribute to β-cell failure in Type 2 diabetes, although this hypothesis remains to be tested in humans.
The diverse roles of protein kinase C in pancreatic β-cell function
Authors: Biden Trevor J. , Schmitz-Peiffer Carsten , Burchfield James G. , Gurisik Ebru , Cantley James , Mitchell Christopher J. , Carpenter Lee 
Published: October 2008

Members of the serine/threonine PKC (protein kinase C) family perform diverse functions in multiple cell types. All members of the family are activated in signalling cascades triggered by occupation of cell surface receptors, but the cPKC (conventional PKC) and nPKC (novel PKC) isoforms are also responsive to fatty acid metabolites. PKC isoforms are involved in various aspects of pancreatic β-cell function, including cell proliferation, differentiation and death, as well as regulation of secretion in response to glucose and muscarinic receptor agonists. Recently, the nPKC isoform, PKCϵ, has also been implicated in the loss of insulin secretory responsiveness that underpins the development of Type 2 diabetes.
The sensitivity of pancreatic β-cells to mitochondrial injuries triggered by lipotoxicity and oxidative stress
Authors: Li Ning , Frigerio Francesca , Maechler Pierre 
Published: October 2008

Pancreatic β-cells are essential for the maintenance of glucose homoeostasis, and dysfunction of these insulin-secreting cells results in the development of diabetes. In the course of events leading from obesity to Type 2 diabetes, several mechanisms are currently envisaged. Among them, lipids and oxidative stress are considered as toxic candidates for the β-cell. The cellular link between fatty acids and ROS (reactive oxygen species) is essentially the mitochondrion, a key organelle for the control of insulin secretion. Mitochondria are the main source of ROS and are also the primary target of oxidative attacks. The present review presents the current knowledge of lipotoxicity related to oxidative stress in the context of mitochondrial function in the β-cell.
Regulation and consequences of differential gene expression in diabetic kidney disease
Authors: Murphy Madeline , Crean John , Brazil Derek P. , Sadlier Denise , Martin Finian , Godson Catherine 
Published: October 2008

DN (diabetic nephropathy) is the leading cause of end-stage renal disease worldwide and develops in 25–40% of patients with Type 1 or Type 2 diabetes mellitus. Elevated blood glucose over long periods together with glomerular hypertension leads to progressive glomerulosclerosis and tubulointerstitial fibrosis in susceptible individuals. Central to the pathology of DN are cytokines and growth factors such as TGF-β (transforming growth factor β) superfamily members, including BMPs (bone morphogenetic protein) and TGF-β1, which play key roles in fibrogenic responses of the kidney, including podocyte loss, mesangial cell hypertrophy, matrix accumulation and tubulointerstitial fibrosis. Many of these responses can be mimicked in in vitro models of cells cultured in high glucose. We have applied differential gene expression technologies to identify novel genes expressed in in vitro and in vivo models of DN and, importantly, in human renal tissue. By mining these datasets and probing the regulation of expression and actions of specific molecules, we have identified novel roles for molecules such as Gremlin, IHG-1 (induced in high glucose-1) and CTGF (connective tissue growth factor) in DN and potential regulators of their bioactions.
Lack of TXNIP protects β-cells against glucotoxicity
Authors: Shalev Anath 
Published: October 2008

Glucotoxicity plays a major role in pancreatic β-cell apoptosis and diabetes progression, but the factors involved have remained largely unknown. Our recent studies have identified TXNIP (thioredoxin-interacting protein) as a novel pro-apoptotic β-cell factor that is induced by glucose, suggesting that TXNIP may play a role in β-cell glucotoxicity. Incubation of INS-1 β-cells and isolated primary mouse and human islets at high glucose levels led to a significant increase in TXNIP as well as in apoptosis. Very similar results were obtained in vivo in islets of diabetic mice. To determine whether TXNIP plays a causative role in glucotoxic β-cell death, we used TXNIP-deficient islets of HcB-19 mice harbouring a natural nonsense mutation in the TXNIP gene. We incubated islets of HcB-19 and C3H control mice at low and high glucose levels and assessed them for TXNIP expression and apoptosis. Interestingly, whereas in C3H islets, high glucose levels led again to significant elevation of TXNIP and apoptosis levels as measured by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) and cleaved caspase 3, no increase in apoptosis was observed in TXNIP-deficient HcB-19 islets, indicating that TXNIP is required for β-cell death caused by glucotoxicity. Thus inhibition of TXNIP protects against glucotoxic β-cell apoptosis and therefore may represent a novel therapeutic approach to halt diabetes progression.
A structural analysis of the transient interaction between the cytochrome bc1 complex and its substrate cytochrome c
Authors: Nyola Ajeeta , Hunte Carola 
Published: October 2008

In cellular respiration, cytochrome c transfers electrons from the cytochrome bc1 complex to cytochrome c oxidase by transiently binding to the membrane proteins. The first X-ray structure of the yeast cytochrome bc1 complex with bound cytochrome c revealed the general architecture of the electron-transfer complex. The interface of the complex is small. The haem moieties are centrally located in a mainly non-polar contact site, which includes a cation–π interaction and is surrounded by complementary charged residues. Only one cytochrome c1-docking site of the dimeric complex is occupied with cytochrome c. The recent 1.9 Å (1 Å=0.1 nm) resolution structure of the complex showed that the interface is highly hydrated. With cytochrome c bound, a higher number of interfacial water molecules are present on the cytochrome c1 interface, whereas its protein surface is not affected. Remarkably, the dimer structure is slightly asymmetric. Univalent cytochrome c binding coincides with conformational changes of the Rieske head domain and subunit QCR6p. Pronounced hydration and a mobility mismatch at the interface with disordered charged residues on the cytochrome c side are favourable for transient binding. Comparison with a new structure of the complex with bound isoform-2 cytochrome c led to the definition of a core interface, which refers to four common interaction pairs including the cation–π interaction. They encircle the haem groups and are surrounded by variable interactions. The core interface may be a feature to gain specificity for formation of the reactive complex. The consistency in the binding interaction despite differences in primary sequence, redox state and crystal contacts, together with crystallization at physiological ionic strength, clearly suggest that the structures show the native bound state of the electron-transfer complex.
Rhodobacter sphaeroides haem protein: a novel cytochrome with nitric oxide dioxygenase activity
Authors: Li Bor-Ran , Anderson J.L. Ross , Mowat Christopher G. , Miles Caroline S. , Reid Graeme A. , Chapman Stephen K. 
Published: October 2008

Rhodobacter sphaeroides produces a novel cytochrome, designated as SHP (sphaeroides haem protein), that is unusual in having asparagine as a redox-labile haem ligand. The gene encoding SHP is contained within an operon that also encodes a DHC (dihaem cytochrome c) and a membrane-associated cytochrome b. DHC and SHP have been shown to have high affinity for each other at low ionic strength (Kd=0.2 μM), and DHC is able to reduce SHP very rapidly. The reduced form of the protein, SHP2+ (reduced or ferrous SHP), has high affinity for both oxygen and nitric oxide (NO). It has been shown that the oxyferrous form, SHP2+–O2 (oxygen-bound form of SHP), reacts rapidly with NO to produce nitrate, whereas SHP2+–NO (the NO-bound form of SHP) will react with superoxide with the same product formed. It is therefore possible that SHP functions physiologically as a nitric oxide dioxygenase, protecting the organism against NO poisoning, and we propose a possible mechanism for this process.
Next-generation sequencing: applications beyond genomes
Authors: Marguerat Samuel , Wilhelm Brian T. , Bähler Jürg 
Published: October 2008

The development of DNA sequencing more than 30 years ago has profoundly impacted biological research. In the last couple of years, remarkable technological innovations have emerged that allow the direct and cost-effective sequencing of complex samples at unprecedented scale and speed. These next-generation technologies make it feasible to sequence not only static genomes, but also entire transcriptomes expressed under different conditions. These and other powerful applications of next-generation sequencing are rapidly revolutionizing the way genomic studies are carried out. Below, we provide a snapshot of these exciting new approaches to understanding the properties and functions of genomes. Given that sequencing-based assays may increasingly supersede microarray-based assays, we also compare and contrast data obtained from these distinct approaches.
Hyperbaric oxygen activates discoidin domain receptor 2 via tumour necrosis factor-α and the p38 MAPK pathway to increase vascular smooth muscle cell migration through matrix metalloproteinase 2
Authors: Shyu Kou-Gi , Wang Bao-Wei , Chang Hang 
Published: October 2008

DDR2 (discoidin domain receptor 2) regulates collagen turnover mediated by SMCs (smooth muscle cells) in atherosclerosis. HBO (hyperbaric oxygen) has been used in medical practice; however, the molecular mechanism of the beneficial effects of HBO is poorly understood. Furthermore, the effect of HBO on DDR2 has not been reported previously. In the present study, we investigated the cellular and molecular mechanisms of DDR2 regulation by HBO in VSMCs (vascular SMCs). Cells were exposed to 2.5 ATA (atmosphere absolute) of oxygen in a hyperbaric chamber. DDR2 protein (3.63-fold) and mRNA (2.34-fold) expression were significantly increased after exposure to 2.5 ATA HBO for 1 h. Addition of SB203580 and p38 MAPK (mitogen-activated protein kinase) siRNA (small interfering RNA) 30 min before HBO inhibited the induction of DDR2 protein. HBO also significantly increased DNA–protein binding activity of Myc/Max. Addition of SB203580 and an anti-TNF-α (tumour necrosis factor-α) monoclonal antibody 30 min before HBO abolished the DNA–protein binding activity induced by HBO. HBO significantly increased the secretion of TNF-α from cultured VSMCs. Exogenous addition of TNF-α significantly increased DDR2 protein expression, whereas anti-TNF-α and anti-(TNF-α receptor) antibodies blocked the induction of DDR2 protein expression. HBO significantly increased VSMC migration and proliferation, whereas DDR2 siRNA inhibited the migration induced by HBO. HBO increased activated MMP2 (matrix metalloproteinase 2) protein expression, and DDR2 siRNA abolished the induction of activated MMP2 expression induced by HBO. In conclusion, HBO activates DDR2 expression in cultured rat VSMCs. HBO-induced DDR2 is mediated by TNF-α and at least in part through the p38 MAPK and Myc pathways.
Effects of pravastatin on functional capacity in patients with chronic obstructive pulmonary disease and pulmonary hypertension
Authors: Lee Tsung-Ming , Chen Chien-Chang , Shen Hsiu-Nien , Chang Nen-Chung 
Published: October 2008

PH (pulmonary hypertension) often complicates the disease course of patients with COPD (chronic obstructive pulmonary disease) and is an indication of a worse prognosis. In the present study, we assessed whether pravastatin administration was effective in improving PH and exercise capacity in COPD patients with PH, and whether the pulmonary protection was mediated by inhibiting ET-1 (endothelin-1) production. In a double-blind parallel design, 53 COPD patients with PH were randomly assigned to receive either placebo or pravastatin (40 mg/day) over a period of 6 months at a medical centre. Baseline characteristics were similar in both groups. The exercise time remained stable throughout the study in the placebo group. After 6 months, the exercise time significantly increased 52% from 660±352 to 1006±316 s (P&lt;0.0001) in pravastatin-treated patients. With pravastatin, echocardiographically derived systolic PAP (pulmonary artery pressure) decreased significantly from 47±8 to 40±6 mmHg. There was significant improvement in the Borg dyspnoea score after administering pravastatin. Despite unchanged plasma ET-1 levels throughout the study, urinary excretion of the peptide was decreased and significantly correlated with an improvement in exercise time in pravastatin-treated patients (r=−0.47, P=0.01). In conclusion, pravastatin significantly improved exercise tolerance, and decreased PH and dyspnoea during exercise in COPD patients with PH, probably by inhibiting ET-1 synthesis.
IGF-I/IGFBP-3 ratio: a mechanistic insight into the metabolic syndrome
Authors: Sierra-Johnson Justo , Romero-Corral Abel , Somers Virend K. , Lopez-Jimenez Francisco , Mälarstig Anders , Brismar Kerstin , Hamsten Anders , Fisher Rachel M. , Hellénius Mai-Lis 
Published: October 2008

Recent reports suggest that IGF (insulin-like growth factor)-I and IGFBP-3 (IGF-binding protein-3) have independent and opposing mechanistic effects on insulin. The aim of the present study was to assess the relationship between the IGF-I/IGFBP-3 ratio and the metabolic syndrome. We examined 3281 subjects (1463 men and 1818 women, aged 20–49 years), otherwise healthy adults, who participated in NHANES III (Third National Health and Nutrition Examination Survey), which has released measurements of IGF-I and IGFBP-3. Insulin resistance was estimated using the computer HOMA2 (homoeostatic model assessment 2) model. The updated ATP-III (Adult Treatment Panel III) definition of the metabolic syndrome was used. We applied adjusted logistic and linear regression models. After adjusting for age and race, men and women in the lowest quartile of the IGF-I/IGFBP-3 ratio were 3-fold more likely to meet the ATP-III definition of the metabolic syndrome and twice as likely to be insulin-resistant. Mean values of the IGF-I/IGFBP-3 ratio decreased significantly as the number of metabolic syndrome components increased (P&lt;0.0001, as determined by ANOVA). The area under the ROC (receiver operating characteristic) curve for detecting insulin resistance using the IGF-I/IGFBP-3 ratio was 0.760, significantly improving upon either protein alone (P=0.01). In conclusion, the IGF-I/IGFBP-3 ratio is significantly associated with the metabolic syndrome. Calculating the ratio of these two proteins may provide insight into the metabolic syndrome clustering phenomenon.
Sex differences in psychological effects of exercise
Authors: Hülya Aşçı F. 
Published: October 2008

The purpose of this study was to investigate sex differences in psychological effects of exercise on university students. University students (73 female and 65 male) were randomly assigned to experimental and control groups by equating sex in each group. The experimental group participated in step dance sessions of 50 min per day, 3 days per week for 10 weeks with 60–80% of their heart rate reserves. Throughout the 10‐week period, the lecture control group was told not to participate in any organized or structured exercise and participated in a lecture that was about the physiological and psychological benefits of exercise. Self‐concept, belief in external control, and trait anxiety of the groups were measured before and after the exercise program. A significant improvement in the psychological variables after the exercise program and more improvement for female exercise participants were expected. Analysis revealed no significant initial differences in self‐concept, belief in external control, and trait anxiety between the two groups or between males and females, other than family and moral/ethical self. Repeated measures analysis of variance revealed that exercise led to less belief in external control and significant improvement in physical self and identity dimensions of self‐concept for the experimental group compared to the control group. However, there was no significant difference in trait anxiety between the two groups after exercise (p>.05). Analysis also revealed that changes in belief in external control, trait anxiety, and self‐concept did not differ with regard to sex. Males and females showed no difference in their improvement on trait anxiety, belief in external control, and most dimensions of self‐concept during the 10 weeks. Only changes in personal and physical self throughout 10‐week period were different for males and females. Exerciser males improved their personal self and physical self scores more than female exercisers and male and female nonexercisers throughout the 10‐week period (p<.05).