bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Mechanisms Involved in the Etiopathogenesis of Malnutrition‐Modulated Diabetes Mellitus
Authors: KANUNGO A. , SAMAL K. C. , SANJEEVI C. B.
Published: July 2010

Abstract: MMDM patients are typically young at onset with low body mass index, require insulin treatment for glycemic control, have insulin resistance, and do not develop ketosis on withdrawal of insulin. WHO's revised classification in 1999, based on the etiopathogenesis of the disease, identifies only two categories: type 1 diabetes and type 2 diabetes. MMDM could be considered as type 1b diabetes. Genetic and immunological studies were done on MDDM patients (n= 72) from Cuttack and healthy controls to understand and to justify its inclusion in the category of type 1b diabetes. Antibodies (Abs) to tyrosine pyrophosphatase (IA2‐Abs), glutamate decarboxylase 65 (GAD65‐Abs), and other minor markers like ICA12 Abs and tissue transglutaminase Abs (TTG‐Abs) were studied. HLA‐DR and DQ were studied for the genetic markers. Of the MMDM patients 30% were positive for either GAD65 or IA‐2 antibodies, and 14% were positive for ICA12 antibodies. All three antibody markers together accounted for 39% of PDDM patients, as some patients were positive for more than one autoantibody. TTG antibodies (specific for Celiac disease) were present in 14/71 (20%) of MMDM patients compared to 3/122 (2%) controls. All four autoantibodies accounted for 53% of PDDM patients, leaving 47% of patients free of known autoantibodies. The autoantibody‐negative PDDM patients were analyzed for HLA and MICA markers, showing that DR7‐DQ9 and MICA allele 9 are increased in this group compared to healthy controls, which suggests an autoimmune response to an unknown dietary autoantigen. We conclude from our data that an autoimmune mechanism is involved in the etiology of MMDM. In addition, the presence of silent celiac disease seen with MMDM patients, which has not yet been reported, is significant. It is important to note that subclinical celiac disease exists with diabetes mellitus and must be considered in the diagnosis of MMDM.
Fas Stimulation Results in Selective Islet Infiltrate Apoptosis in Situ and Reversal of Diabetes
Authors: DHARNIDHARKA VIKAS R. , PATTEN YANCY VAN , BAHJAT F. RENA , CLARE‐SALZLER MICHAEL
Published: July 2010

Abstract: Breakdown of peripheral T cell regulation due to defective antigen‐activated apoptosis may lead to autoimmunity. In the nonobese diabetic (NOD) mouse model of type 1 diabetes mellitus, we have demonstrated defects in T cell activation and peripheral apoptosis. Stimulation of the Fas pathway by a Fas receptor agonist led to enhanced in vitro apoptosis and in vivo selective apoptosis of islet‐infiltrating lymphocytes. Administration of the Fas agonist immediately after onset of diabetes led to reversal of diabetes in NOD mice. Inducing peripheral T cell apoptosis may be a potential method for reversal of autoimmune diabetes.
Apoptosis of Autoreactive CD8 Lymphocytes as a Potential Mechanism for the Abrogation of Type 1 Diabetes by Islet‐Specific TNF‐α Expression at a Time When the Autoimmune Process Is Already Ongoing
Authors: CHRISTEN URS , VON HERRATH MATTHIAS G.
Published: July 2010

Abstract: The role of TNF‐α in type 1 diabetes pathogenesis is controversial. Using double transgenic mice expressing (i) the glycoprotein (GP) of lymphocytic choriomeningitis virus (LCMV) as an islet self‐antigen and (ii) TNF‐α under control of a tetracycline‐regulated promotor system (tTA) in the pancreatic β cells, we could previously demonstrate a differential effect of TNF‐α on the incidence of type 1 diabetes. Most interestingly, late expression of TNF‐α resulted in a reversion of mice that were already diabetic to a nondiabetic state. Here we provide a model of how experienced autoaggressive CD8 lymphocytes are dying by apoptosis as a result of β cell‐specific TNF‐α expression at a time when the autoimmune process is already ongoing.
The PEVKEK Region of the Pyridoxal Phosphate Binding Domain of GAD65 Expresses a Dominant B Cell Epitope for Type 1 Diabetes Sera
Authors: TONG JONATHAN C. , MYERS MARK A. , MACKAY IAN R. , ZIMMET PAUL Z. , ROWLEY MERRILL J.
Published: July 2010

Abstract: Molecular mimicry between the 65‐kDa isoform of glutamic acid decarboxylase (GAD65) and the protein 2C (P2C) of Coxsackie B4 virus (CBV) may initiate human type 1 diabetes. GAD65 contains a motif that has a 6‐amino acid identity with CBV‐P2C (PEVKEK), whereas the weakly autoantigenic isoform, GAD67, contains PEVKTK. A human‐derived monoclonal antibody (mAb) MICA3 reacts with a surface loop of GAD65 that includes PEVKEK, and mutagenic deletion of this loop was shown to reduce reactivity of GAD with the mAb by 70%. To establish that the PEVKEK motif on GAD65 contains a major epitope for diabetes sera and to identify the amino acids involved, mutants of nucleotides of GAD65 and GAD67 at sites in the PEVKEK motif were created and the expressed proteins used for radioimmunoprecipitation (RIP) tests with sera from patients with type 1 diabetes. A potent mouse mAb (GAD6) to GAD65, and a rabbit polyclonal antibody (AB108) to GAD67, were used to standardize the reactivity of the diabetes sera with the mutant molecules. Of 45 type 1 diabetes sera tested, 30 (67%) had an 80% or greater reduction of reactivity to GAD65Δ258‐270 vs. intact GAD65. Various single‐surface amino acids in the PEVKEK epitope region of GAD65 were mutated, but most molecules carrying these mutations reacted similarly to the parent molecule. However after point mutation of the equivalent motif of GAD67 (PEVKTK to PEVKEK), there was an increase in the reactivity of 12 of 49 (24%) type 1 diabetes sera tested; 7 of 8 sera reactive with GAD67 showed increased reactivity with GAD67T273E, and 5 previously negative sera gained reactivity with GAD67T273E. Thus, the PEVKEK motif on GAD65 contributes to serologic reactivity of type 1 diabetes sera. This favors the hypothesis that CBV infection causes type 1 diabetes by the process of viral mimicry with cross‐reactivity to a critical epitope of GAD65.
Prevalence of ICA‐12 and Other Autoantibodies in North Indian Patients with Early‐Onset Diabetes
Authors: TANDON N. , SHTAUVERE‐BRAMEUS A. , HAGOPIAN W. A. , SANJEEVI C. B.
Published: July 2010

Abstract: This study attempts to assess the prevalence of various autoantibodies in early‐onset diabetics in northern India, with emphasis on antibodies against glutamic acid decarboxylase (GAD65), IA‐2, ICA‐12, 21‐hydroxylase (21‐OH), and tissue transglutaminase (TTG). GAD65 and IA‐2 antibodies were found to be present in approximately 26% of cases of type 1 diabetes. A subset of patients clinically diagnosed to have MMDM appears to have an autoimmune etiology, with more than 20% showing serpositivity for IA‐2 antibodies. Antibodies against ICA‐12 were prevalent in both type 1 diabetes and MMDM. Approximately one of seven patients with type 1 diabetes showed erological evidence of celiac disease.
BCG Vaccination and GAD65 and IA‐2 Autoantibodies in Autoimmune Diabetes in Southern India
Authors: SANJEEVI C. B. , DAS ASHOK K. , SHTAUVERE‐BRAMEUS A.
Published: July 2010

Abstract: This paper reports a study to determine whether BCG vaccination is associated with an increase or decrease in GAD65 and I‐A2 autoantibodies in cases of IDDM and NIDDM in southern India. It is concluded that BCG vaccination has an immunomodulatory role in these diseases.
ICA12 Autoantibodies Are Associated with Non‐DR3/Non‐DR4 in Patients with Latent Autoimmune Diabetes in Adults from Northern India
Authors: GUPTA M. , TANDON N. , SHTAUVERE‐BRAMEUS A. , SANJEEVI C. B.
Published: July 2010

Abstract: Associations of HLA‐DR3/DQ2 with GAD65 and DR4 with IA‐2 antibodies in insulin‐dependent diabetes mellitus (IDDM) and DR3/DQ2 with GAD65 antibodies in latent autoimmune diabetes in adult (LADA) patients are known. The aim of the present study was to look for association of HLA DR and DQ with GAD65, IA2 and ICA12 antibodies in IDDM (n= 97), LADA (n= 32), and malnutrition‐modulated diabetes mellitus (MMDM) (n= 22) patients from northern India. HLA genotyping was done by the PCR‐SSO method. Antibodies to GAD65, IA‐2, and ICA‐12 were assayed by radioimmunoassay using 35S‐labeled recombinant human GAD65, IA2, and ICA12 using the in vitro transcription‐translation method. We found DR3 (29% vs. 11%) and DQ2 (36% vs. 14%) were increased in GAD65 antibody‐positive compared to GAD65 antibody‐negative IDDM patients (P > 0.05). ICA 12 antibodies were increased in either DR3 or DR4 (84% vs. 69%) positives compared to non‐DR3/DR4 IDDM patients (P > 0.05). However in LADA patients, ICA12 was increased in non‐DR3/DR4 patients compared to DR3‐ or DR4‐positive patients (P < 0.05). In conclusion, in LADA patients, ICA 12 is associated with non‐DR3/DR4 patients. No association between HLA and autoantibodies was seen in MMDM patients.
A Comparative Study of the Knowledge, Beliefs, and Practices of Diabetic Patients Cared for at a Teaching Hospital (Free Service) and Those Cared for by Private Practitioners (Paid Service)
Authors: SIVAGNANAM G. , NAMASIVAYAM K. , RAJASEKARAN M. , THIRUMALAIKOLUNDUSUBRAMANIAN P. , RAVINDRANATH C.
Published: July 2010

Abstract: The aim of this study was to determine and compare the knowledge, beliefs, and practices of diabetics receiving free medical care and those paying for medical care in Tamilnadu, India. A questionnaire was administered to elicit diabetic patients' knowledge regarding diet, exercise, adverse effects, habits, and other matters; their beliefs about diabetes; and their practices regarding diet, medication, and self‐monitoring. The results showed a large gap between knowledge and action in both groups and a need for increased efforts toward patient education regarding diabetes.
Electron Transfer Through Bridging Molecular Structures
Authors: MAYOR M. , BÜSCHEL M. , FROMM K. M. , LEHN J.‐M. , DAUB J.
Published: July 2010

Abstract: Pairs of reducible pentakis(thiophenyl)benzene subunits are linked by different molecular structures as model compounds for reducible molecular‐wire‐type synthons showing varying electron‐transfer ability as a function of the bridging structures, consisting of either para‐divinylbenzene, bis‐hydrazone, or diacetylene. Their electron‐transfer ability from one reducible subunit to the other was investigated by electrochemical and spectroelectrochemical methods. In the case of the bis‐hydrazone bridge and the diacetylene bridge, the solid‐state structures support the experimental findings. While the para‐divinylbenzene bridge completely isolates the reducible subunits (class I system) the diacetylene bridge electronically connects the two reducible structures (class III system), demonstrating its potential application as a “molecular wire.” The bis‐hydrazone linked dimer displays electronic communication only to a small extend, which was only observed in the spectroelectrochemical investigation. The diacetylene connection as active electron‐transfer linker together with poly(thiophenyl)benzene as reducible subunits was used to design more complex molecular architectures. Linear rodlike struktures did allow adjustment of the length of these type of molecular wires and investigation of the extent of electron mobility. Cyclic structures addressed the possibility of moving electrons on a bent molecular wire.
Charging Effects, Forces, and Conduction in Molecular Wire Systems
Authors: EMBERLY ELDON G. , KIRCZENOW GEORGE
Published: July 2010

Abstract: Recently, experiments have shown that effects arising from charging and conformational changes in a molecular wire due to an applied voltage bias can have a significant influence on the transport characteristics of the system. We introduce a tractable theoretical approach based on Landauer theory and total energy methods that treats transport nonlinearities, conformational changes, and charging effects in molecular wires in a unified way. We apply this approach to molecular wires consisting of short chain molecules with different electronic and structural properties bonded to metal contacts. We find that the nonlinear conductance characteristics of these systems are remarkably similar and can be understood in terms of a single physical mechanism. We predict that negative differential resistance should occur at high bias in such molecular wires due to the combined effects of charging and conformational changes on their electronic structure.
Molecular Wire‐Nanotube Interfacial Effects on Electron Transport
Authors: FAGAS GIORGOS , CUNIBERTI GIANAURELIO , RICHTER KLAUS
Published: July 2010

Abstract: We discuss the conductance of a molecular bridge between mesoscopic electrodes supporting low‐dimensional transport and bearing an internal structure. As an example for such nanoelectrodes we assume semi‐infinite (carbon) nanotubes. In the Landauer scattering matrix approach, we show that the conductance of this hybrid is very sensitive to the geometry of the contact, unlike the usual behavior in the presence of bulk electrodes.
From Castration‐Induced Apoptosis of Prostatic Epithelium to the Use of Apoptotic Genes in the Treatment of Prostate Cancer
Authors: ZHANG YE , NAN BICHENG , YU JIANG , SNABBOON TITHI , ANDRIANI FRANCESCA , MARCELLI MARCO
Published: July 2010

Abstract: Current knowledge of the mechanisms regulating androgen‐ablation‐induced apoptosis is reviewed, and our efforts to develop a system in which genes of the apoptotic pathway are used to induce therapeutic apoptosis in experimental models of prostate cancer are described.
p53 and Anti‐p53 Antibodies as Possible Markers of a Switch Towards a Neoplastic Phenotype in Patients Infected by Helicobacter pylori
Authors: LOSI E. , MOLINARI A. M. , GAZZERRO P. , DE LUNA L. ORTEGA , FERA M. T. , CARBONE M. , CATANIA M. R. , HASTY D. L. , ROSSANO F.
Published: July 2010

Abstract: Helicobacter pylori is a definite carcinogen whose mechanism of action is still unknown. The aim of this work was (1) to determine the presence of p53 protein and related antibodies in patients affected by various gastric pathologies and chronically infected with H. pylori, and (2) to try to discover a test to be used as a marker of a possible switch towards a neoplastic phenotype.
Current Understanding of Food Allergy
Authors: BURKS WESLEY
Published: July 2010

Abstract: IgE‐mediated hypersensitivity reactions account for the majority of well‐documented food allergy reactions, but non‐IgE‐mediated immune mechanisms do cause some hypersensitivity disorders. A variety of gastrointestinal, cutaneous, respiratory, and generalized symptoms and syndromes have been associated with IgE‐mediated food allergy. The diagnostic approach to adverse food reactions begins with a careful medical history and physical examination. Laboratory studies may then be used appropriately in the evaluation. Once the diagnosis of food allergy is established, the only proven therapy is the strict elimination of the food from the patient's diet. Studies in both children and adults indicate that symptomatic reactivity to food allergens is often lost over time, except possibly reactions to peanuts, tree nuts, and seafood.
Phosphomannose Isomerase, a Novel Plant Selection System
Authors: PRIVALLE LAURA S.
Published: July 2010

Abstract: Phosphomannose isomerase (PMI), an enzyme not present in many plants, catalyzes the reversible interconversion of mannose 6‐phosphate and fructose 6‐phosphate. Plant cells lacking this enzyme are incapable of surviving on synthetic medium containing mannose. Thus PMI/mannose selection has utility in the identification of transformed plant cells. As part of the safety assessment transgenic plants undergo before commercialization, PMI has been evaluated for its potential allergenicity. Purified PMI protein was readily digestible in a simulated gastric environment. PMI has no sequence homology to known allergens, does not contain multiple disulfide bonds, and has no N‐glycosylation consensus sequences. No detectable changes in glycoprotein profiles were detected in PMI‐transformed plants as compared to nontransgenic controls. These results indicate that PMI lacks many of the attributes associated with known oral allergens.
The Dog as a Model for Food Allergy
Authors: BUCHANAN BOB B. , FRICK OSCAR L.
Published: July 2010

Abstract: Research during the past decade has shown the dog to be an excellent model for human food allergies. Humans and dogs share many of the same allergies to foods. Furthermore, the dog model shows clinical symptoms typical of humans, that is, both experience vomiting and diarrhea. Present results suggest that the dog may provide a means to test genetically modified foods for unsuspected allergens.
Neurokinin Receptors Modulate the Neurochemical Actions of Cocaine
Authors: NOAILLES P.‐A. H. , ANGULO J. A.
Published: July 2010

Abstract:The psychostimulant cocaine is an indirect agonist that increases synaptic dopamine (DA) by binding with high affinity to the DA transporter (DAT) and blocking the active transport of synaptic DA back into the terminal. The resulting increase in extracellular DA alters postsynaptic activity in the circuitry of the basal ganglia. This study examines the role of neurokinin receptors on cocaine‐evoked DA overflow in the striatum. Male Sprague‐Dawley rats (n= 8) were treated with cocaine (10 mg/kg body weight i.p.) acutely or chronically. The pattern of DA release was assessed usingin vivomicrodialysis. In separate experiments two different neurokinin‐1 (NK‐1) receptor antagonists (d‐Arg1, d‐Pro2, d‐Trp7,9, Leu11, or L‐733,060) were perfused via the microdialysis probe for one hour in awake and freely moving animals that were subsequently injected i.p. with cocaine. Throughout the procedure, DA release was monitored at 1/2‐hour intervals at a flow rate of 1 μl/min. In the groups of rats preperfused with NK‐1 antagonists into the striatum, the cocaine‐evoked release of DA was significantly reduced. This result suggests a significant role for the NK‐1 receptor in the striatal response to acute and chronic cocaine administration.
Abused Inhalants and Central Reward Pathways
Authors: RIEGEL ARTHUR C. , FRENCH EDWARD D.
Published: July 2010

Abstract:Inhalant abuse remains a significant health problem among the younger segment of society. In fact, the use of inhalants in this population trails only that of nicotine, alcohol, and marijuana. Toluene is a common ingredient in many of the substances sought out for inhalation abuse, apparently for its euphorigenic and hallucinogenic effects. Because drugs of abuse share the common property of altering the activity of mesolimbic dopamine neurons, it is reasonable to suspect that toluene‐induced changes in this CNS pathway may underlie its abuse potential. Here we will providein vivoandin vitroelectrophysiological data and behavioral evidence linking toluene exposure in rats to activation of mesolimbic dopamine neurons. Exposure of rats to 11,000 ppm of inhaled toluene produced time‐dependent activation of dopamine neurons within the midbrain ventral tegmental area (VTA). In the rat brain slice preparation, perfusion with toluene (23‐822 μM) also evoked an increase in activity of both dopamine and nondopamine neurons within the VTA. These excitatory effects could not be found in adjacent non‐VTA nuclei, nor were they sensitive to the glutamate antagonists CGS19755 or CNQX. In behavioral studies, systemic administration of toluene produced a dose‐dependent locomotor hyperactivity that was attenuated by either pretreatment with the D2 dopamine receptor antagonist remoxipride or by 6‐hydroxydopamine lesions of the nucleus accumbens. These findings show that toluene can activate dopamine neurons within the mesolimbic reward pathway, an effect that may underlie the abuse potential of inhaled substances containing toluene.
Effects of Chronic Maternal Ethanol Exposure on Hippocampal and Striatal Morphology in Offspring
Authors: RAMOS ALBERTO JAVIER , EVRARD SERGIO GUSTAVO , TAGLIAFERRO PATRICIA , TRICÁRICO MARÍA VICTORIA , BRUSCO ALICIA
Published: July 2010

Abstract: Astrocytes and serotoninergic neurons play a role in central nervous system (CNS) development, probably through serotonin (5HT) stimulation of the glial 5HT1A receptor. Activation of 5HT1A receptors causes the release of S‐100β, a glial derived growth factor. In vitro, astrocytes are profoundly altered by chronic maternal ethanol exposure (CMEE). CMEE is also associated with reduced 5HT brain levels and abnormal development of the serotoninergic system. In the present study we analyzed the hippocampal and striatal serotoninergic innervation and astroglial cells in the offspring of CMEE mothers. Female Wistar rats were orally exposed to ethanol 6.6% (v/v) ad libitum for 6 weeks before breeding and during gestation. After parturition, rat mothers continued receiving ethanol until pups reached 21 days old. The control group received water ad libitum. Rat offspring brains were processed by immunocytochemistry using antibodies directed to GFAP, serotonin transporter (5HTT), or S‐100β protein. Hippocampus and striatum were studied by computer‐assisted image analysis. Cell area of GFAP+ astrocytes, surface of 5HTT+ fibers per area unit, and relative optical density (ROD) of S‐100β+ astrocytes were measured and statistically processed. Our results show that astroglial GFAP was increased (astrocytes were hypertrophied) and 5HTT+ fibers were increased in both the hippocampal CA‐1 area and the striatum. On the other hand, S‐100β ROD was increased only in the hippocampal CA‐1 area but not in the striatum. The different response of the studied regions is an interesting result considering evidence of a close 5HT/astroglial relation during CNS development. These differences could be due to different gradients of development in the studied areas and/or different responses of those areas to the effect of maternal ethanol exposure since the first stages of embryonic development.
Nicotine Reduces the Secretion of Alzheimer's β‐Amyloid Precursor Protein Containing β‐Amyloid Peptide in the Rat without Altering Synaptic Proteins
Authors: LAHIRI D. K. , UTSUKI T. , CHEN D. , FARLOW M. R. , SHOAIB M. , INGRAM D. K. , GREIG N. H.
Published: July 2010

Abstract:Alzheimer's disease (AD) is characterized by cerebrovascular deposition of the amyloid β‐peptide (Aβ), which is derived from a larger β‐amyloid precursor protein (βAPP). Altered metabolism of βAPP, resulting in increased Aβ production, appears central in the neuropathology of AD. The processing of the holoprotein βAPP by different “secretase” enzymes results in three major carboxyl‐truncated species. One species, which results from the cleavage of βAPP by γ‐secretase, is secreted into the cerebrospinal fluid (CSF) and is called sAPPγ as it contains an intact Aβ domain. Moreover, AD is characterized by cholinergic dysfunction and the loss of synaptic proteins. Reports of an inverse relation between nicotine intake, due to cigarette smoking, and the incidence of AD prompted us to investigate the effects of nicotine on βAPP processing and synaptic proteins in rats and in cell culture. Nicotine, 1 and 8 mg/kg/day, doses commensurate with cigarette smoking, and a higher but well tolerated dose, respectively, was administered over 14 days to rats. Levels of sAPP in the CSF sample were evaluated by Western blot analysis. The higher dose significantly increased levels of total sAPP; however, both doses significantly reduced sAPPγ, which contains the amyloidogenic portion of Aβ. These actions were blocked by nicotinic receptor antagonism. Nicotinic antagonists alone had no effect on either total sAPP or sAPPγ levels in CSF. Nicotine did not significantly change the intracellular levels of total βAPP in rat brain extracts, which is consistent with neuronal cell culture data. Similarly, levels of vesicular protein, such as synaptophysin, and presynaptic terminal protein SNAP‐25 were unaffected by nicotine treatment bothin vivoand in cell culture experiments. Taken together, these results suggest that nicotine modifies βAPP processing away from the formation of potentially amyloidogenic products, without altering the levels of synaptic proteins, and that this can potentially offer therapeutic potential for Alzheimer's disease.
Striatal Postsynaptic Ultrastructural Alterations Following Methylenedioxymethamphetamine Administration
Authors: FORNAI F. , GESI M. , LENZI P. , FERRUCCI M. , PELLEGRINI A. , RUGGIERI S. , CASINI A. , PAPARELLI A.
Published: July 2010

Abstract:Amphetamine derivatives, such as methamphetamine (METH) and 3,4‐methylenedioxymethamphetamine (MDMA), act as monoaminergic neurotoxins in the central nervous system. Although there are slight differences in their mechanism of action, these compounds share a final common pathway, which involves dopamine release and oxidative stress. Apart from striatal toxicity involving monoamine axons, no previous report evidenced any alteration at the striatal level concerning postsynaptic sites. Given the potential toxicity for extracellular dopamine at the striatal level, and the hypothesis for neurotoxic effects of dopamine on striatal medium‐sized neurons in Huntington's disease, we evaluated at an ultrastructural level the effects of MDMA on intrinsic striatal neurons of the mouse. In this study, administering MDMA, we noted ultrastructural alterations of striatal postsynaptic GABAergic cells consisting of neuronal inclusions shaped as whorls of concentric membranes. These whorls stained for ubiquitin but not for synuclein and represent the first morphologic correlate of striatal postsynaptic effects induced by MDMA.
Identification of Susceptibility Genes for Complex Metabolic Diseases
Authors: BOGARDUS CLIFTON , BAIER LESLIE , PERMANA PASKA , PROCHAZKA MICHAL , WOLFORD JOHANNA , HANSON ROBERT
Published: July 2010

Abstract: There are few successful attempts to identify genes for common, non‐Mendelian diseases such as diabetes, hyperlipidemia, hypertension, etc. Such common disorders are typically both metabolically and genetically complex and the genetic technologies to identify their underlying susceptibility genes are still in their infancy. Nonetheless, genetic strategies have emerged that, when the technologies are fully developed, should allow similar success rates as for Mendelian diseases.
Desaturation and Elongation of Fatty Acids and Insulin Action
Authors: VESSBY B. , GUSTAFSSON I‐B. , TENGBLAD S. , BOBERG M. , ANDERSSON A.
Published: July 2010

Abstract: Insulin resistance is characterized by specific changes of the composition of fatty acids in the serum lipids and in the skeletal muscle membranes. Impaired insulin sensitivity is associated with high proportions of palmitic (16:0) acid and low levels of linoleic (18:2 n‐6) acid in serum. In addition, there are apparent changes of the fatty acid desaturase activities, suggesting an increased activity of the Δ9 and Δ6 desaturases and a decreased activity of the Δ5 desaturase. The activity of the fatty acid desaturases is regulated by long‐chain polyunsaturated fatty acids and insulin and is probably also dependent on the degree of physical activity. A high ratio between arachidonic (20:4 n‐6) and dihomo‐gamma linolenic (20:3 n‐6) acid, as a measure of Δ5 desaturase activity, in the skeletal muscle phospholipids has been related to good insulin sensitivity. Available knowledge seems to indicate that the degree of saturation of the body lipids, and especially the proportion of palmitic acid in the lipid membranes, may be critical for insulin sensitivity. The strong relationships between the Δ5 desaturase activity, a high content of long‐chain polyunsaturated fatty acids in the skeletal muscle, and insulin sensitivity may be due to parallel effects of diet and/or physical activity on the fatty acid composition and on insulin sensitivity.
The Sphingomyelin‐Signaling Pathway in Skeletal Muscles and Its Role in Regulation of Glucose Uptake
Authors: GÖRSKI JAN , DOBRZYN AGNIESZKA , ZENDZIAN‐PIOTROWSKA MALGORZATA
Published: July 2010

Abstract: Sphingomyelin has been shown to be a source of bioactive compounds. This sphingolipid is located mostly in the outer layer of the plasma membrane and in the membranes of organelles. Sphingomyelin located in the plasma membrane is hydrolyzed into ceramide and phosphorylcholine. Ceramide is the principal second messenger in the sphingomyelin transmembrane signaling pathway. Products of ceramide metabolism, namely, sphingosine, sphingosine‐1‐phosphate, and ceramide‐1‐phosphate, also exert broad biological effects. The major effects of ceramide are induction of differentiation, inhibition of proliferation, regulation of inflammatory processes, and induction of apoptosis. There is also convincing evidence that ceramide counteracts insulin‐stimulated glucose uptake. Ceramides are also present in skeletal muscles. We investigated ceramide metabolism in different skeletal muscle types of the rat at rest and after prolonged exercise of moderate intensity. Exercise reduced the total content of ceramide fatty acids and changed their composition in each muscle type. These data indicate that the sphingomyelin‐signaling pathway functions in skeletal muscles and that its activity is downregulated during prolonged exercise. The content of ceramide in the muscles was inversely related to 2‐deoxyglucose uptake by the muscles. This indicates that ceramide may be involved in regulation of glucose uptake by skeletal muscles in vivo.
Perinatal Supply and Metabolism of Long‐Chain Polyunsaturated Fatty Acids
Authors: LARQUE ELVIRA , DEMMELMAIR HANS , KOLETZKO BERTHOLD
Published: July 2010

Abstract: The long‐chain polyunsaturated fatty acids, arachidonic (AA) and docosahexaenoic acid (DHA), are essential structural lipid components of biomembranes. During pregnancy, long‐chain polyunsaturated fatty acids (LC‐PUFA) are preferentially transferred from mother to fetus across the placenta. This placental transfer is mediated by specific fatty acid binding and transfer proteins. After birth, preterm and full‐term babies are capable of converting linoleic and α‐linolenic acids into AA and DHA, respectively, as demonstrated by studies using stable isotopes, but the activity of this endogenous LC‐PUFA synthesis is very low. Breast milk provides preformed LC‐PUFA, and breast‐fed infants have higher LC‐PUFA levels in plasma and tissue phospholipids than infants fed conventional formulas. Supplementation of formulas with different sources of LC‐PUFA can normalize LC‐PUFA status in the recipient infants relative to reference groups fed human milk. Some, but not all, randomized, double‐masked placebo‐controlled clinical trials in preterm and healthy full‐term infants demonstrated benefits of formula supplementation with DHA and AA for development of visual acuity up to 1 year of age and of complex neural and cognitive functions. From the available data, we conclude that LC‐PUFA are conditionally essential substrates during early life that are related to the quality of growth and development. Therefore, a dietary supply during pregnancy, lactation, and early childhood that avoids the occurrence of LC‐PUFA depletion is desirable, as was recently recommended by an expert consensus workshop of the Child Health Foundation.
Energy Transfer in Acute Diabetic Rat Hearts
Authors: ZIEGELHÖFFER A. , RAVINGEROVÁ T. , WACZULÍKOVÁ I. , CÁRSKY J. , NECKÁR J. , ZIEGELHÖFFER‐MIHALOVICOVÁ B. , STYK J.
Published: July 2010

Abstract:Objectives—Hearts of rats with diabetes mellitus (DM) are characterized by energy demands exceeding their energy production, but they might also exhibit decreased vulnerability to ischemia and calcium overload. This indicates adaptation in cardiac energetics (CE), where energy transport is not rate‐limiting.Aim—This study was designed to elucidate the functional significance of the DM‐induced adaptation in CE by investigating the formation of mitochondrial contact sites (MiCS), facilitating the Ca‐dependent/high‐capacity energy transfer from mitochondria, in conjunction with testing the ischemic tolerance (IT) of hearts.Methods—After 1 week of streptozotocin‐induced DM (45 mg/kg iv), the hearts of male diabetic and age‐matched control rats (C) were isolated and Langendorff‐perfused with either 1.6 or 2.2 mmol/L of CaCl2. MiCS formation was assessed by cytochemical detection of mCPK octamers and was quantified stereologically as MiCS to mitochondrial surface ratio (SS). IT was evaluated in anesthetized open‐chest animals subjected to 30‐min occlusion of the LAD coronary artery followed by 4‐h reperfusion, by monitoring ischemic arrhythmias and by measuring the size of infarction (tetrazolium double staining).Results—In C hearts, increasing Ca2+induced both positive inotropic response (dP/dtincrease from 2270 ± 220 to 2955 ± 229,p< 0.01) and elevated MiCS formation (SSincrease from 0.070 ± 0.011 to 0.123 ± 0.012,p< 0.01). In DM hearts, basic MiCS formation was already comparable with that induced by elevated Ca2+in C hearts and could not be further stimulated by Ca2+. In C, ventricular tachycardia represented 55.4% of the total arrhythmias and occurred in 90% of the animals. In DM rats, the arrhythmia profile was similar to that in C, and the incidence of tachyarrhythmias and their severity were not enhanced (arrhythmia score: 3.18 ± 0.4 vs. 3.30 ± 0.3 in C). The infarct size normalized to the size of area at risk was smaller in the DM than in C hearts (52.3 ± 5.8% vs. 69.2 ± 2.2%, respectively;p< 0.05).Conclusions—Ca‐signaling represents the link between energy delivery from mitochondria (via MiCS) and energy requirements of the heart. In DM hearts, energy transport via MiCS is elevated to the maximum value. This contributes to increased resistance of DM hearts to irreversible cell damage.
Ion Channel—like Properties of the Na+/K+Pump
Authors: ARTIGAS PABLO , GADSBY DAVID C.
Published: July 2010

Abstract:Ion pumps and exchangers are considered to be different from ion channels for two principal reasons. Ion pumps move ionsagainst, whereas ion channels allow ions to movewith, the electrochemical potential gradient, and pumps transport ions relatively slowly, ∼102s−1, whereas channels conduct ions rapidly, ∼107s−1. However, the latter high rate refers only to the open pore, and yet all ion channels contain at least one gate. Not surprisingly, the conformational changes associated with channel gating occur with kinetics similar to those of ion pumping. Indeed, ion pumps may be viewed as ion channels with two gates, one external to, and the other internal to, the ion binding cavity. The simple operational rule for such a pump is that the two gates should never be open simultaneously; otherwise, the pump would become a channel and conduct dissipative fluxes several orders of magnitude larger than, and in the opposite direction to, the active transport fluxes. Analyses of Na+ion movements mediated by the Na+/K+pump under various conditions have suggested that in at least one, short‐lived, conformation of the pump, an ion‐channel‐like structure, closed at its intracellular end, connects the extracellular solution with the ion binding sites deep in the protein core. Here we use the marine toxin, palytoxin, to act on Na+/K+pumps in outside‐out patches excised from cardiac myocytes and so transform the pumps into nonselective cation channels which we study using macroscopic, and single‐channel, recording. We find that gating of the palytoxin‐induced channels is regulated by the pump's natural ligands. Thus, external K+congeners tend to close, and external Na+tends to open, an extracellular gate, whereas ATP acts from the cytoplasmic solution to open an intracellular gate. These gating influences echo the normal ion occlusion and deocclusion reactions that first entrap two extracellular K+ions within the interior of the pump (between the two gates) and then release them to the cytoplasmic side in a step accelerated by ATP. These results offer the promise of being able to examine ion occlusion and deocclusion steps at the microscopic level in single Na+/K+pump molecules.
Sodium‐Calcium Exchange Stoichiometry
Authors: KANG TONG MOOK , STECIUK MARK , HILGEMANN DONALD WILLIAM
Published: July 2010

Abstract: The stoichiometry of cardiac sodium‐calcium exchange is of profound importance to understanding its physiological function, and recent work challenges a simple 3‐to‐1 stoichiometry. We present a refined 3‐to‐1 exchange model that can explain recently measured reversal potentials that are close to those expected for a 4‐to‐1 exchanger. The model assumes that 1 calcium and 1 sodium ion can be transported by the exchanger, albeit more slowly than 3 sodium ions or 1 calcium ion. In this model, currents and calcium fluxes reverse at different potentials; resting free calcium would always be higher than expected for a perfect 3‐to‐1 exchange process. To test models such as this, we have developed new methods to study ion transport processes in giant membrane patches independent of, or in parallel with, current measurements. Briefly, ion‐selective electrodes or fluorescent ion indicators are used to detect concentration changes in the pipette, close to the membrane, upon activation of transport activity. Preliminary results are presented.
NCX1 Surface Expression
Authors: RAHAMIMOFF HANNAH , REN XIAOYAN , KIMCHI‐SARFATY CHAVA , AMBUDKAR SURESH , KASIR JUDITH
Published: July 2010

Abstract:The rat Na+/Ca2+exchanger isoforms of the NCX1 gene have 14 cysteine residues. Each of these cysteines can be mutated individually to alanine or serine without loss of functional expression in transfected HEK293 cells. Yet sequential exchange starting from the amino terminal end of three or more cysteines results in reduced transport activity and surface expression. As more and more cysteines are replaced, transport activity and surface expression decrease in parallel, and the cysteineless mutant exhibits only traces of Na+/Ca2+exchange activity and surface expression. No significant differences are detected in the amount of total cell exchanger protein between the wild‐type exchanger and its functional or nonfunctional cysteine mutants. Reduced surface expression of the Na+/Ca2+exchanger NCX1 is also observed when HEK293 cells expressing the transporter are treated with cyclosporin A (CsA) or with PSC833. The reductions in transport activity and surface expression are concentration dependent and parallel. No reduction is obtained in the total amount of exchanger protein by CsA or PSC833 treatment, suggesting that the effects of these drugs on NCX1 expression are posttranslational. FK506 and rapamycin treatment of HEK293 cells expressing rat NCX1 isoforms has no effect on transport activity, surface expression, or the total amount of exchanger protein in the transfected cells.
Potassium‐Dependent Sodium‐Calcium Exchange through the Eye of the Fly
Authors: WEBEL R. , HAUG‐COLLET K. , PEARSON B. , SZERENCSEI R. T. , WINKFEIN R. J. , SCHNETKAMP P. P.M. , COLLEY N. J.
Published: July 2010

Abstract: In this review, we describe the characterization of a Drosophila sodium/calcium‐potassium exchanger, Nckx30C. Sodium/calcium (‐potassium) exchangers (NCX and NCKX) are required for the rapid removal of calcium in excitable cells. The deduced protein topology for NCKX30C is similar to that of mammalian NCKX, with 5 hydrophobic domains in the amino terminus separated from 6 at the carboxy‐terminal end by a large intracellular loop. NCKX30C functions as a potassium‐dependent sodium‐calcium exchanger and is expressed in adult neurons and during ventral nerve cord development in the embryo. Nckx30C is expressed in a dorsal/ventral pattern in the eye‐antennal disc, suggesting that large fluxes of calcium may be occurring during imaginal disc development in the larvae. NCKX30C may play a critical role in modulating calcium during development as well as in the removal of calcium and maintenance of calcium homeostasis in adults.
Na/Ca Exchange in Heart Failure
Authors: POGWIZD STEVEN M. , BERS DONALD M.
Published: July 2010

Abstract: Congestive heart failure (HF) is characterized by contractile dysfunction and a high incidence of sudden death from nonreentrant ventricular arrhythmias, both of which involve altered intracellular calcium handling. The focus of this article is on the critical role of the Na/Ca exchanger. We demonstrate that upregulation of Na/Ca exchanger unloads the sarcoplasmic reticulum (SR), leading to contractile dysfunction. At the same time, Na/Ca exchanger underlies the arrhythmogenic transient inward current (Iti) in HF. Preserved β‐adrenergic responsiveness in HF plays a crucial role in increasing SR Ca load, leading to SR Ca release and activation of Iti. In addition, decreased IK1 (inward rectifier) current in HF destabilizes resting membrane potential (Em) and further enhances arrhythmogenesis mediated by the upregulated Na/Ca exchanger. We thus propose a new paradigm in which upregulated Na/Ca exchanger in HF plays a dual role in underlying both the contractile dysfunction and arrhythmogenesis in the failing heart. Therapeutic approaches to the treatment of HF will need to balance increasing SR Ca load with the arrhythmogenic effects of SR Ca overload that involve activation of Iti carried by Na/Ca exchanger.
Ramazzini Foundation Cancer Program
Authors: SOFFRITTI MORANDO , BELPOGGI FIORELLA , MINARDI FRANCO , MALTONI CESARE
Published: July 2010

Abstract: The Ramazzini Foundation research program was started over thirty years ago. The features of this program are: (1) systematic and integrated project design; (2) consistency over time; (3) homogeneity of approach: key members of the team remain unchanged; and (4) choice to work on new frontiers of scientific research. The program centers mainly on three projects: Project 1: experimental carcinogenicity bioassays; Project 2: experimental anticarcinogenesis assays to identify factors and active principles (compounds) capable of opposing the onset of tumors while being suitable for preventive/chemopreventive intervention; Project 3: epidemiological studies, both descriptive and analytical, on tumor incidence and mortality in persons professionally and environmentally exposed to industrial carcinogenic risks. The project involving experimental carcinogenicity bioassays for the identification of exogenous carcinogens (environmental and industrial above all) began in 1966. This project has included 398 experimental bioassays on 200 compounds/agents using some 148,000 animals monitored until their spontaneous death. Among the studies already concluded, 47 agents have shown “clear evidence” of carcinogenicity. The results have demonstrated for the first time that (1) vinyl chloride can cause liver angiosarcoma as well as other tumors; (2) benzene is carcinogenic in experimental animals for various tissues and organs; (3) formaldehyde may produce lymphomas and leukemias; and (4) methyl‐tert‐butyl ether (MTBE), the most common oxygenated additive used in gasolines, can cause lymphomas/leukemias. Many of the results achieved have led to the introduction of norms and measures of primary prevention.
Results of Long‐Term Carcinogenicity Bioassay on Vinyl Acetate Monomer in Sprague‐Dawley Rats
Authors: MINARDI FRANCO , BELPOGGI FIORELLA , SOFFRITTI MORANDO , CILIBERTI ADRIANO , LAURIOLA MICHELINA , CATTIN ELISA , MALTONI CESARE
Published: July 2010

Abstract: Vinyl acetate monomer (VAM) was administered in drinking water supplied ad libitum at doses of 5,000, 1,000, and 0 ppm (v/v) to 17‐week‐old Sprague‐Dawley rats (breeders) and to 12‐day embryos (offspring). Treatment lasted for 104 weeks; thereafter, animals were kept under control conditions until spontaneous death. VAM was found to cause an increase in total malignant tumors and in carcinomas and/or precursor lesions of the oral cavity, lips, tongue, esophagus, and forestomach. Based on these data, VAM must be considered a multipotent carcinogen.
Asbestos Fibers Contributing to the Induction of Human Malignant Mesothelioma
Authors: SUZUKI YASUNOSUKE , YUEN STEVEN R.
Published: July 2010

Abstract: To elucidate the features of the asbestos fibers contributing to the induction of human malignant mesothelioma, we used high‐resolution analytical electron microscopy to determine the type, number, and dimensions of asbestos fibers in lung and mesothelial tissues in 168 cases of mesothelioma. Results: 1. Asbestos fibers were present in almost all of the lung and mesothelial tissues from the mesothelioma cases. 2. The most common types of asbestos fibers in lung were either an admixture of chrysotile with amphiboles, amphibole alone, and occasionally chrysotile alone. In mesothelial tissues, most asbestos fibers were chrysotile. 3. In lung, amosite fibers were greatest in number followed by chrysotile, crocidolite, tremolite/actinolite, and anthophyllite. In mesothelial tissues, chrysotile fibers were 30.3 times more common than amphiboles. 4. In some mesothelioma cases, the only asbestos fibers detected in either lung or mesothelial tissue were chrysotile fibers. 5. The average number of asbestos fibers in both lung and mesothelial tissues was two orders of magnitude greater than the number found in the general population. 6. The majority of asbestos fibers in lung and mesothelial tissues were shorter than 5 μm in length. Conclusions: 1) Fiber analysis of both lung and mesothelial tissues must be done to determine the types of asbestos fibers associated with the induction of human malignant mesothelioma; 2) short, thin asbestos fibers should be included in the list of fiber types contributing to the induction of human malignant mesothelioma; 3) Results support the induction of human malignant mesothelioma by chrysotile.
Sex‐Related Influences on the Neurobiology of Emotionally Influenced Memory
Authors: CAHILL LARRY
Published: July 2010

Abstract: In a recent report, the National Academy of Sciences concluded that ‘Sex matters. Sex, that is, being male or female, is an important basic human variable that should be considered when designing and analyzing studies in all areas and at all levels of biomedical and health‐related research.’1 Recent findings from my laboratory concerning neural mechanisms of emotionally influenced memory further support this conclusion. This article first provides a brief, general overview of sex‐related influences on brain and cognition. Upon this background, recent findings from my laboratory and others are described, demonstrating sex‐related influences on neural mechanisms underlying emotionally influenced, explicit recall of emotionally arousing events. Both the hemispheric involvement of the human amygdala in memory for emotionally arousing events and the impairing effect of β‐adrenergic blockade on memory for emotional events exhibit pronounced sex‐related differences. We interpret both of these effects in the context of evidence indicating hemispheric specialization in the processing of global/wholistic versus local/fine detail aspects of a situation. The more general conclusion that we draw from these investigations is that theories of the neurobiology of emotion and memory must begin to account for the seemingly substantial influences of sex.