Inhibitory protein-protein interactions of the SIRT1 deacetylase are choreographed by post-translational modification

Regulation of SIRT1 activity is vital to energy homeostasis and plays important roles in many diseases. We previously showed that insulin triggers the epigenetic regulator DBC1 to prime SIRT1 for repression by the multifunctional trafficking protein PACS-2. Here, we show that liver DBC1/PACS-2 regulates the diurnal inhibition of SIRT1, which is critically important for insulin-dependent switch in fuel metabolism from fat to glucose oxidation. We present the x-ray structure of the DBC1 S1-like domain that binds SIRT1 and an NMR characterization of how the SIRT1 N-terminal region engages DBC1. This interaction is inhibited by acetylation of K112 of DBC1 and stimulated by the insulin-dependent phosphorylation of human SIRT1 at S162 and S172, catalyzed sequentially by CK2 and GSK3, resulting in the PACS-2-dependent inhibition of nuclear SIRT1 enzymatic activity and translocation of the deacetylase in the cytoplasm. Finally, we discuss how defects in the DBC1/PACS-2-controlled SIRT1 inhibitory pathway are associated with disease, including obesity and non-alcoholic fatty liver disease.

Hepatic ketogenesis regulates lipid homeostasis via ACSL1-mediated fatty acid partitioning

Liver-derived ketone bodies play a crucial role in fasting energy homeostasis by fueling the brain and peripheral tissues. Ketogenesis also acts as a conduit to remove excess acetyl-CoA generated from fatty acid oxidation and protects against diet-induced hepatic steatosis. Surprisingly, no study has examined the role of ketogenesis in fasting-associated hepatocellular lipid metabolism. Ketogenesis is driven by the rate-limiting mitochondrial enzyme 3-hydroxymethylglutaryl CoA synthase (HMGCS2) abundantly expressed in the liver. Here, we show that ketogenic insufficiency via disruption of hepatic HMGCS2 exacerbates liver steatosis in fasted chow and high-fat-fed mice. We found that the hepatic steatosis is driven by increased fatty acid partitioning to the endoplasmic reticulum (ER) for re-esterification via acyl-CoA synthetase long-chain family member 1 (ACSL1). Mechanistically, acetyl-CoA accumulation from impaired hepatic ketogenesis is responsible for the elevated translocation of ACSL1 to the ER. Moreover, we show increased ER-localized ACSL1 and re-esterification of lipids in human NASH displaying impaired hepatic ketogenesis. Finally, we show that L-carnitine, which buffers excess acetyl-CoA, decreases the ER-associated ACSL1 and alleviates hepatic steatosis. Thus, ketogenesis via controlling hepatocellular acetyl-CoA homeostasis regulates lipid partitioning and protects against hepatic steatosis.

Liraglutide Protects Against Diastolic Dysfunction and Improves Ventricular Protein Translation

PURPOSE

Diastolic dysfunction is an increasingly common cardiac pathology linked to heart failure with preserved ejection fraction. Previous studies have implicated glucagon-like peptide 1 (GLP-1) receptor agonists as potential therapies for improving diastolic dysfunction. In this study, we investigate the physiologic and metabolic changes in a mouse model of angiotensin II (AngII)-mediated diastolic dysfunction with and without the GLP-1 receptor agonist liraglutide (Lira).

METHODS

Mice were divided into sham, AngII, or AngII+Lira therapy for 4 weeks. Mice were monitored for cardiac function, weight change, and blood pressure at baseline and after 4 weeks of treatment. After 4 weeks of treatment, tissue was collected for histology, protein analysis, targeted metabolomics, and protein synthesis assays.

RESULTS

AngII treatment causes diastolic dysfunction when compared to sham mice. Lira partially prevents this dysfunction. The improvement in function in Lira mice is associated with dramatic changes in amino acid accumulation in the heart. Lira mice also have improved markers of protein translation by Western blot and increased protein synthesis by puromycin assay, suggesting that increased protein turnover protects against fibrotic remodeling and diastolic dysfunction seen in the AngII cohort. Lira mice also lost lean muscle mass compared to the AngII cohort, raising concerns about peripheral muscle scavenging as a source of the increased amino acids in the heart.

CONCLUSIONS

Lira therapy protects against AngII-mediated diastolic dysfunction, at least in part by promoting amino acid uptake and protein turnover in the heart. Liraglutide therapy is associated with loss of mean muscle mass, and long-term studies are warranted to investigate sarcopenia and frailty with liraglutide therapy in the setting of diastolic disease.

Myocardial brain-derived neurotrophic factor regulates cardiac bioenergetics through the transcription factor Yin Yang 1

AIMS

Brain-derived neurotrophic factor (BDNF) is markedly decreased in heart failure patients. Both BDNF and its receptor, tropomyosin-related kinase receptor (TrkB), are expressed in cardiomyocytes; however, the role of myocardial BDNF signalling in cardiac pathophysiology is poorly understood. Here, we investigated the role of BDNF/TrkB signalling in cardiac stress response to exercise and pathological stress.

METHODS AND RESULTS

We found that myocardial BDNF expression was increased in mice with swimming exercise but decreased in a mouse heart failure model and human failing hearts. Cardiac-specific TrkB knockout (cTrkB KO) mice displayed a blunted adaptive cardiac response to exercise, with attenuated upregulation of transcription factor networks controlling mitochondrial biogenesis/metabolism, including peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α). In response to pathological stress (transaortic constriction, TAC), cTrkB KO mice showed an exacerbated heart failure progression. The downregulation of PGC-1α in cTrkB KO mice exposed to exercise or TAC resulted in decreased cardiac energetics. We further unravelled that BDNF induces PGC-1α upregulation and bioenergetics through a novel signalling pathway, the pleiotropic transcription factor Yin Yang 1.

CONCLUSION

Taken together, our findings suggest that myocardial BDNF plays a critical role in regulating cellular energetics in the cardiac stress response.

Abstract P3050: The Adropin-GPR19 Signaling Axis In Diabetic Cardiomyopathy

Background: Diabetic cardiomyopathy (DCM) is a major complication of diabetes and has been recognized as a cause of heart failure independent of other common risk factors for cardiac disease. In DCM, increased free fatty acid availability and decreased myocardial glucose uptake lead to a reliance on fatty acid oxidation for ATP generation. This loss of metabolic flexibility can reduce cardiac plasticity in response to stress. Energetic inefficiency in diabetic hearts may have profound implications for cardiac function under conditions of increased workload, and therefore therapeutic approaches are warranted. Alleviating metabolic inflexibility, by promoting cardiac glucose utilization, has been proposed as a potential strategy to reverse cardiomyopathy in diabetic and obese patients. Adropin is a liver- and brain-secreted peptide hormone shown to regulate fuel metabolism in a number of tissues, including the heart. Adropin levels are significantly reduced in obese and diabetic human subjects, and this decrease is linked to increased adiposity, insulin resistance, and impaired glucose tolerance. Our lab recently showed that adropin treatment restores glucose oxidation activity in vivo by reducing the expression of the mitochondrial acetyltransferase enzyme GCN5L1. The reduction in GCN5L1 abundance altered the acetylation and activity of fuel metabolism enzymes to favor glucose utilization; however, the mechanism that underlies this effect remains unknown. Our data suggests that the class A orphan G-coupled protein receptor, GPR19, acts as a putative cellular receptor for adropin in cardiac cells to regulate mitochondrial bioenergetic output.

Hypothesis: We hypothesize that adropin-GPR19 signaling regulates GCN5L1 expression, which in turn promotes the deacetylation and activity of pyruvate dehydrogenase to restore glucose utilization in the diabetic heart.

Methods: We used a novel whole-body GPR19 knockout mouse to perform a preliminary characterization of the effects of GPR19 depletion on cardiac and whole-body physiology. Using in vivo metabolic approaches, we report that GPR19 KO mice exhibit sex-dependent glucose intolerance, and display markers of altered cardiac energy metabolism.

Conclusions: These findings further define the fundamental role of the adropin-GPR19 signaling pathway in the regulation of metabolic homeostasis, and thus highlight a potential target for therapeutic interventions in DCM.

Intestinal HIF-2α Regulates GLP-1 Secretion via Lipid Sensing in L-Cells

BACKGROUND & AIMS

Compelling evidence shows that glucagon-like peptide-1 (GLP-1) has a profound effect in restoring normoglycemia in type 2 diabetic patients by increasing pancreatic insulin secretion. Although L-cells are the primary source of circulating GLP-1, the current therapies do not target L-cells to increase GLP-1 levels. Our study aimed to determine the molecular underpinnings of GLP-1 secretion as an impetus to identify new interventions to target endogenous L-cells.

METHODS

We used genetic mouse models of intestine-specific overexpression of hypoxia-inducible factor (HIF)-1α and HIF-2α (Vhl^ΔIE), conditional overexpression of intestinal HIF-2α (Hif-2α^{LSL;Vilin-Cre/ERT2}), and intestine-specific HIF-2α knockout mice (Hif-2α^ΔIE) to show that HIF signaling, especially HIF-2α, regulates GLP-1 secretion.

RESULTS

Our data show that intestinal HIF signaling improved glucose homeostasis in a GLP-1-dependent manner. Intestinal HIF potentiated GLP-1 secretion via the lipid sensor G-protein-coupled receptor (GPR)40 enriched in L-cells. We show that HIF-2α regulates GPR40 in L-cells and potentiates fatty acid-induced GLP-1 secretion via extracellular regulated kinase (ERK). Using a genetic model of intestine-specific overexpression of HIF-2α, we show that HIF-2α is sufficient to increase GLP-1 levels and attenuate diet-induced metabolic perturbations such as visceral adiposity, glucose intolerance, and hepatic steatosis. Lastly, we show that intestinal HIF-2α signaling acts as a priming mechanism crucial for postprandial lipid-mediated GLP-1 secretion. Thus, disruption of intestinal HIF-2α decreases GLP-1 secretion.

CONCLUSIONS

In summary, we show that intestinal HIF signaling, particularly HIF-2α, regulates the lipid sensor GPR40, which is crucial for the lipid-mediated GLP-1 secretion, and suggest that HIF-2α is a potential target to induce endogenous GLP-1 secretion.

Pleiotropic adipose Treg subsets, defined by Atf3 expression, modulate adipocyte energy expenditure and weight loss

Chronic obesity occurs when there is imbalance between caloric intake and energy expenditure. It is now clear that immune cells, through their communication with adipocytes, can drive or suppress adipocyte energy expenditure, thus regulating weight gain and obesity. Adipose tissue resident regulatory T cells (aTregs) are a dominant, unique CD4+ T cell population in the adipose tissue depots of mice and humans. Here we show that the transcription factor Activating Transcription Factor 3 (Atf3), defines a population of aTregs that secrete opioid-like peptides called Methionine-Enkephalins (Met-Enk). We show that aTreg-derived Met-Enk increases adipocyte function and energy expenditure by upregulating Uncoupling Protein 1 (Ucp-1) and other genes associated with adipocyte thermogenesis. Loss of Atf3 expression in aTregs, resulted in loss of Met-Enk expressing aTregs and conversely, resulted in increased Interelukin-10 (IL-10)-secreting aTregs. Physiologically, Atf3+ aTregs are required to maintain metabolic homeostasis and loss of Atf3+ aTregs increased insulin resistance in mice. Taken together, our data reveal that distinct aTreg populations with unique gene expression and cytokine secretion profiles, work together to modulate adipocyte function and energy expenditure.

Tregs facilitate obesity and insulin resistance via a Blimp-1-IL-10 axis

Adipose-resident Tregs protect against systemic inflammation and metabolic disease by limiting expansion of pro-inflammatory cells, preserving insulin sensitivity and maintaining glucose tolerance. Although their basic markers and roles have been studied, less is known about the transcriptional machinery regulating their differentiation and function.

B lymphocyte-induced maturation protein-1 (Blimp-1) is a transcriptional regulator known to be involved in development, polarization, and maintenance of various immune cells including CD4+ T cells. Using Blimp-1 reporter mice, we discovered that Blimp-1 is constitutively expressed in a subset of visceral adipose tissue (VAT) Tregs, and that Blimp-1+ VAT Tregs are phenotypically distinct from their Blimp-1-counterparts. We also found that Treg-specific Blimp-1 deletion led to altered differentiation and function of VAT and inguinal adipose tissue Tregs. Surprisingly, during diet-induced obesity, Blimp-1 Treg deficient mice gained less weight, had reduced body fat percentage, and exhibited improved insulin sensitivity compared to wild type mice. Furthermore, this was accompanied by upregulation of thermogenic genes such as Ucp1, Prdm16 and Dio2 in inguinal adipose tissue, and increased overall fatty acid oxidation. It has previously been shown that IL-10 can induce thermogenesis. Therefore, we repeated these experiments utilizing mice with Treg-specific deletion of IL-10 and found that they phenocopied the Blimp-1 Treg deficient mice. Based on these results, we hypothesize that cross-talk between Tregs and adipocytes via a Blimp-1-IL-10 axis suppresses thermogenesis, and that absence of Blimp-1+ Tregs is metabolically protective during diet-induced obesity.

Endogenous Glucose Production in Critical Illness

Regulation of endogenous glucose production (EGP) by hormonal, neuronal, and metabolic signaling pathways contributes to the maintenance of euglycemia under normal physiologic conditions. EGP is defined by the generation of glucose from substrates through glycogenolysis and gluconeogenesis, usually in fasted states, for local and systemic use. Abnormal increases in EGP are noted in patients with diabetes mellitus type 2, and elevated EGP may also impact the pathogenesis of nonalcoholic fatty liver disease and congestive heart failure. In this narrative review, we performed a literature search in PubMed to identify recently published English language articles characterizing EGP in critical illness. Evidence from preclinical and clinical studies demonstrates that critical illness can disrupt EGP through multiple mechanisms including increased systemic inflammation, counterregulatory hormone and catecholamine release, alterations in the hypothalamic-pituitary axis, insulin resistance, lactic acidosis, and iatrogenic insults such as vasopressors and glucocorticoids administered as part of clinical care. EGP contributes to hyperglycemia in critical illness when abnormally elevated and to hypoglycemia when abnormally depressed, each of which has been independently associated with increased mortality. Increased EGP may also promote protein catabolism that could worsen critical illness myopathy and impede recovery. Better understanding of the mechanisms and factors contributing to dysregulated EGP in critical illness may help in the development of therapeutic strategies that promote euglycemia, reduce intensive care unit-associated catabolism, and improve patient outcomes.

Sustained mitochondrial biogenesis is essential to maintain caloric restriction-induced beige adipocytes

BACKGROUND

Caloric restriction (CR) delays the onset of metabolic and age-related disorders. Recent studies have demonstrated that formation of beige adipocytes induced by CR is strongly associated with extracellular remodeling in adipose tissue, decrease in adipose tissue inflammation, and improved systemic metabolic homeostasis. However, beige adipocytes rapidly transition to white upon CR withdrawal through unclear mechanisms.

MATERIALS AND METHODS

Six-week old C57BL6 mice were fed with 40% CR chow diet for 6 weeks. Subsequently, one group of mice was switched back to ad libitum chow diet, which was continued for additional 2 weeks. Adipose tissues were assessed histologically and biochemically for beige adipocytes.

RESULTS

Beige adipocytes induced by CR rapidly transition to white adipocytes when CR is withdrawn independent of parkin-mediated mitophagy. We demonstrate that the involution of mitochondria during CR withdrawal is strongly linked with a decrease in mitochondrial biogenesis. We further demonstrate that beige-to-white fat transition upon β3-AR agonist-withdrawal could be attenuated by CR, partly via maintenance of mitochondrial biogenesis.

CONCLUSION

In the model of CR, our study highlights the dominant role of mitochondrial biogenesis in the maintenance of beige adipocytes. We propose that loss of beige adipocytes upon β3-AR agonist withdrawal could be attenuated by CR.

Blimp-1 in adipose resident Tregs controls adipocyte beiging and obesity

Visceral adipose tissue regulatory T cells (VAT Tregs) protect against systemic inflammation and metabolic disease by limiting expansion of pro-inflammatory Th1 cells and M1 macrophages, and by preserving insulin sensitivity and glucose tolerance. Although their basic markers and roles have been studied, less is known about the transcriptional machinery regulating their differentiation and function.

B lymphocyte-induced maturation protein-1 (Blimp-1) is a transcriptional regulator known to be involved in the development, polarization, and maintenance of various immune cells including CD4+ T cells. Using Blimp-1 reporter mice, we discovered that Blimp-1 is constitutively expressed in a subset of VAT Tregs compared to lymphoid Tregs, and that Blimp-1+ VAT Tregs are phenotypically distinct from their Blimp-1− counterparts. Blimp-1 is not required for VAT Treg development, however Treg-specific deletion of Blimp-1 led to unique changes in VAT Treg markers in lean versus obese adipose tissue. In addition, Blimp-1 knockout mice fed high fat diet had fewer adipose-resident NK cells and increased CD8 T cells. Surprisingly, loss of Blimp-1+ Tregs led to less adipose tissue IL-10, increased expression of thermogenic genes, reduced body fat, decreased weight, and improved insulin sensitivity. Based on these data, we hypothesize that Blimp-1+ Treg dependent IL-10 production suppresses adipocyte beiging, and that loss of these cells results in increased thermogenesis, greater weight loss and improved insulin sensitivity in obese mice.

Slc20a1/Pit1 and Slc20a2/Pit2 are essential for normal skeletal myofiber function and survival

Low blood phosphate (Pi) reduces muscle function in hypophosphatemic disorders. Which Pi transporters are required and whether hormonal changes due to hypophosphatemia contribute to muscle function is unknown. To address these questions we generated a series of conditional knockout mice lacking one or both house-keeping Pi transporters Pit1 and Pit2 in skeletal muscle (sm), using the postnatally expressed human skeletal actin-cre. Simultaneous conditional deletion of both transporters caused skeletal muscle atrophy, resulting in death by postnatal day P13. smPit1-/-, smPit2-/- and three allele mutants are fertile and have normal body weights, suggesting a high degree of redundance for the two transporters in skeletal muscle. However, these mice show a gene-dose dependent reduction in running activity also seen in another hypophosphatemic model (Hyp mice). In contrast to Hyp mice, grip strength is preserved. Further evaluation of the mechanism shows reduced ERK1/2 activation and stimulation of AMP kinase in skeletal muscle from smPit1-/-; smPit2-/- mice consistent with energy-stress. Similarly, C2C12 myoblasts show a reduced oxygen consumption rate mediated by Pi transport-dependent and ERK1/2-dependent metabolic Pi sensing pathways. In conclusion, we here show that Pit1 and Pit2 are essential for normal myofiber function and survival, insights which may improve management of hypophosphatemic myopathy.

Te-based chalcogenide materials for selector applications

The implementation of dense, one-selector one-resistor (1S1R), resistive switching memory arrays, can be achieved with an appropriate selector for correct information storage and retrieval. Ovonic threshold switches (OTS) based on chalcogenide materials are a strong candidate, but their low thermal stability is one of the key factors that prevents rapid adoption by emerging resistive switching memory technologies. A previously developed map for phase change materials is expanded and improved for OTS materials. Selected materials from different areas of the map, belonging to binary Ge-Te and Si-Te systems, are explored. Several routes, including Si doping and reduction of Te amount, are used to increase the crystallization temperature. Selector devices, with areas as small as 55 × 55 nm2, were electrically assessed. Sub-threshold conduction models, based on Poole-Frenkel conduction mechanism, are applied to fresh samples in order to extract as-processed material parameters, such as trap height and density of defects, tailoring of which could be an important element for designing a suitable OTS material. Finally, a glass transition temperature estimation model is applied to Te-based materials in order to predict materials that might have the required thermal stability. A lower average number of p-electrons is correlated with a good thermal stability.

Prevention of diet-induced hepatic steatosis and hepatic insulin resistance by second generation antisense oligonucleotides targeted to the longevity gene mIndy (Slc13a5)

Reducing the expression of the Indy (I'm Not Dead Yet) gene in lower organisms extends life span by mechanisms resembling caloric restriction. Similarly, deletion of the mammalian homolog, mIndy (Slc13a5), encoding for a plasma membrane tricarboxylate transporter, protects from aging- and diet-induced adiposity and insulin resistance in mice. The organ specific contribution to this phenotype is unknown. We examined the impact of selective inducible hepatic knockdown of mIndy on whole body lipid and glucose metabolism using 2′-O-methoxyethyl chimeric anti-sense oligonucleotides (ASOs) in high-fat fed rats. 4-week treatment with 2′-O-methoxyethyl chimeric ASO reduced mIndy mRNA expression by 91% (P<0.001) compared to control ASO. Besides similar body weights between both groups, mIndy-ASO treatment lead to a 74% reduction in fasting plasma insulin concentrations as well as a 35% reduction in plasma triglycerides. Moreover, hepatic triglyceride content was significantly reduced by the knockdown of mIndy, likely mediating a trend to decreased basal rates of endogenous glucose production as well as an increased suppression of hepatic glucose production by 25% during a hyperinsulinemic-euglycemic clamp. Together, these data suggest that inducible liver-selective reduction of mIndy in rats is able to ameliorate hepatic steatosis and insulin resistance, conditions occurring with high calorie diets and during aging.

Nanoscopic structural rearrangements of the Cu-filament in conductive-bridge memories

The electrochemical reactions triggering resistive switching in conductive-bridge resistive random access memory (CBRAM) are spatially confined in few tens of nm(3). The formation and dissolution of nanoscopic Cu-filaments rely on the displacement of ions in such confined volume, and it is driven by the electric field induced ion migration and nanoscaled redox reactions. The stochastic nature of these fundamental processes leads to a large variability of the device performance. In this work, a combination of two- and three-dimensional scanning probe microscopy (SPM) techniques are used to study the conductive filament (CF) formation, rupture and its nanoscopic structural rearrangements. The high spatial confinement of our approach enables to locally induce RS in a confined area and image it in 3D. A conical shape of the CF is consistently observed, indicating that the ion migration is the rate limiting step in the filament formation when using high quality dielectrics as switching layers. The sub-10 nm electrical contact size of the AFM tip is used to study the filament's dissolution and detect the hopping conduction of Cu during the CF rupture. We consistently observe a tunnel gap formation associated with the tip-induced filament reset. Finally, aiming to match the fundamental understanding with the integrated device operations, we apply scalpel SPM to failed memory cells and directly observe the appearance of filament multiplicity as a major source of failures and variability in CBRAM.

Switching mechanism in two-terminal vanadium dioxide devices

Two-terminal thin film VO2 devices show an abrupt decrease of resistance when the current or voltage applied exceeds a threshold value. This phenomenon is often described as a field-induced metal-insulator transition. We fabricate nano-scale devices with different electrode separations down to 100 nm and study how the dc switching voltage and current depend on device size and temperature. Our observations are consistent with a Joule heating mechanism governing the switching. Pulsed measurements show a switching time to the high resistance state of the order of one hundred nanoseconds, consistent with heat dissipation time. In spite of the Joule heating mechanism which is expected to induce device degradation, devices can be switched for more than 10(10) cycles making VO2 a promising material for nanoelectronic applications.

Cyclin D1-Cdk4 controls glucose metabolism independently of cell cycle progression

Insulin constitutes a major evolutionarily conserved hormonal axis for maintaining glucose homeostasis^1-3; dysregulation of this axis causes diabetes^2,4. PGC-1α links insulin signaling to the expression of glucose and lipid metabolic genes^5-7. GCN5 acetylates PGC-1α and suppresses its transcriptional activity, whereas SIRT1 deacetylates and activates PGC-1α^8,9. Although insulin is a mitogenic signal in proliferative cells^10,11, whether components of the cell cycle machinery contribute to insulin’s metabolic action is poorly understood. Herein, we report that insulin activates cyclin D1-CDK4, which, in turn, increases GCN5 acetyltransferase activity and suppresses hepatic glucose production independently of cell cycle progression. Through a cell-based high throughput chemical screen, we identified a CDK4 inhibitor that potently decreases PGC-1α acetylation. Insulin/GSK3β signaling induces cyclin D1 protein stability via sequestering cyclin D1 in the nucleus. In parallel, dietary amino acids increase hepatic cyclin D1 mRNA transcripts. Activated cyclin D1-CDK4 kinase phosphorylates and activates GCN5, which then acetylates and inhibits PGC-1α activity on gluconeogenic genes. Loss of hepatic cyclin D1 results in increased gluconeogenesis and hyperglycemia. In diabetic models, cyclin D1-CDK4 is chronically elevated and refractory to fasting/feeding transitions; nevertheless further activation of this kinase normalizes glycemia. Our findings show that insulin uses components of the cell cycle machinery in post-mitotic cells to control glucose homeostasis independently of cell division.

Transport spectroscopy of a single dopant in a gated silicon nanowire

We report on spectroscopy of a single dopant atom in silicon by resonant tunneling between source and drain of a gated nanowire etched from silicon on insulator. The electronic states of this dopant isolated in the channel appear as resonances in the low temperature conductance at energies below the conduction band edge. We observe the two possible charge states successively occupied by spin-up and spin-down electrons under magnetic field. The first resonance is consistent with the binding energy of the neutral D0 state of an arsenic donor. The second resonance shows a reduced charging energy due to the electrostatic coupling of the charged D- state with electrodes. Excited states and Zeeman splitting under magnetic field present large energies potentially useful to build atomic scale devices.

Oxidative stress and dysregulation of NAD(P)H oxidase and antioxidant enzymes in diet-induced metabolic syndrome

Previously, we have demonstrated that chronic consumption of a high-fat, high-refined sugar (HFS) diet results in metabolic syndrome which is marked by obesity, insulin resistance, hyperlipidemia, and hypertension in Fischer rats. Metabolic syndrome in this model is associated with oxidative stress, avid nitric oxide (NO) inactivation by reactive oxygen species (ROS), diminished NO bioavailability, and dysregulation of NO synthase isotypes. Although occurrence of oxidative stress and its impact on NO metabolism are well established, the molecular source(s) of ROS in this model is unknown. In an attempt to explore this issue, we measured protein expressions of the key ROS-producing enzyme, NAD(P)H oxidase, and the main antioxidant enzymes, superoxide dismutase (CuZn SOD and Mn SOD), catalase, glutathione peroxidase (GPX), and heme oxygenase-2 (HO-2), in the kidney and aorta of Fischer rats fed an HFS or low-fat, complex-carbohydrate diet for 7 months. In addition, plasma lipid peroxidation product (malondialdehyde) as well as endothelium-dependent and -independent vasorelaxation (aorta rings) was determined. The results showed a significant upregulation of gp91(phox) subunit of NAD(P)H oxidase and downregulations of SOD isoforms, GPX, and HO-2 in the kidney and aorta of the HFS-fed animals. This was associated with increased plasma malondialdehyde concentration and impaired vasodilatory response to acetylcholine, but not the NO donor, Na nitroprusside. The latter findings confirm the presence of oxidative stress and endothelial dysfunction in the HFS-fed rats. Oxidative stress and endothelial dysfunction in the diet-induced metabolic syndrome are accompanied by upregulation of NAD(P)H oxidase, pointing to increased ROS production capacity, and downregulation of SOD isoforms, GPX, and HO-2, the key enzymes in the antioxidant defense system.

A high-fat, refined-carbohydrate diet induces endothelial dysfunction and oxidant/antioxidant imbalance and depresses NOS protein expression

We tested whether consumption of a high-fat, high-sucrose (HFS) diet can affect endothelium-dependent relaxation, whether this precedes the development of diet-induced hypertension previously noted in this model, and whether it is mediated, in part, by changes in nitric oxide synthase (NOS) and/or NOS regulatory proteins. Female Fischer rats were fed either a HFS diet or standard low-fat, complex-carbohydrate chow starting at 2 mo of age for 7 mo. Vasoconstrictive response to KCl and phenylephrine was similar in both groups. Vasorelaxation to acetylcholine was significantly impaired in the HFS animals, and there were no differences in relaxation to sodium nitroprusside, suggesting that the endothelial dysfunction is due, at least in part, to nitric oxide deficiency. HFS consumption decreased protein expression of endothelial NOS in aorta, renal, and heart tissues, neuronal NOS in kidney, heart, aorta, and brain, and inducible NOS in heart and aorta. Caveolin-1 and soluble guanylate cyclase protein expression did not change, but AKT protein expression decreased in heart and aorta and increased in kidney tissue. Consumption of HFS diet raised brain carbonyl content and plasma hydrogen peroxide concentration and diminished plasma total antioxidant capacity. Because blood pressure, which is known to eventually rise in this model, was not as yet significantly elevated, the present data suggest that endothelial dysfunction precedes the onset of diet-induced hypertension. The lack of a quantitative change in caveolin-1 and soluble guanylate cyclase protein content indicates that alteration in these proteins is not responsible for the endothelial dysfunction. Thus nitric oxide deficiency combined with antioxidant/oxidant imbalance, appears to be a primary factor in the development of endothelial dysfunction in this model.

Synthesis of polyhydroxyindolizidines from 5,6-dihydro-2H-pyran-2-one

(1aR,5aR,5bS,6S,7S)-6,7-Di-tert-butoxy-5-oxo-pyrrolidino[1,2-b]isoxazolidino[4,5-c]tetrahydropyran (8) prepared by (1,3)-dipolar cycloaddition of the cyclic nitrone 6 derived from tartaric acid to 5,6-dihydro-2H-pyran-2-one (7) was transformed into indolizidine 11 via a sequence of reactions involving methanolysis of the lactone ring, intramolecular alkylation of the nitrogen atom promoted by a carbontetrabromide-triphenylphosphine mixture and hydrogenolysis of the N single bond O bond. Decarboxylation of 11 provided known 7-hydroxylentiginosine derivative 14, whereas oxidative decarboxylation gave indolizidine 15 structurally related to castanospermine.

Coherence and polarization of light propagating through scattering media and biological tissues

The degree of polarization of light propagating through scattering media was measured as a function of the sample thickness in a Mach-Zehnder interferometer at a wavelength of lambda = 633 nm. For polystyrene microspheres of diameters 200, 430, and 940 nm, depolarization began to appear for thicknesses larger than 23, 19, and 15 scattering mean free paths (SMFP's), respectively, where the coherently detected scattered component dominates the ballistic component. For large particles (940 nm) the initial polarization survived partially in the scattering regime and progressively vanished up to the detection limit of our setup. This phenomenon was similarly observed in diluted blood from 12.5 to 280 SMFP's. Beyond this thickness the fluctuating parallel and crossed components of polarization became random. A dual-channel interferometer allowed us to detect simultaneously the low-frequency fluctuations of both polarized components through a few millimeters in liver tissue.

[The evaluation of endometrial invasion of cervical Ib grade carcinoma]

Depth and extension of infiltration into uterine corpus with regard to 5 years survival in 33 patients in which Wertheim-Meigs surgery was done due to cervical cancer stage Ib is estimated in this paper. Endometrial stromal invasion or depth invasion less than 1/2 of myometrium at the site of internal ostium were of similar (91.7% > 5 years survival time) as an invasion confined solely to uterine cervix (86.9% > 5 years survival). Invasion of more than 1/2 of myometrium was associated with poor prognosis (46.7% 5-years survival). Bad prognosis (16.6% 5-year survival time) in patients with deep and extensive of uterine corpus and fundus should be tied to massive infiltration increased hematogenous and lymphatic dissemination. None of patients with deep and extensive invasion, lymph nodes metastases and uterine vasa embolies did survive 5 years period of time. These patients need individual postoperative adjuvant therapy.

[Vascular invasion and prognostic factors in cervical Ib grade cancer without metastases in lymph nodes]

We were looking for presence, severity and extension of the invasion of vessels, with regard to the prognosis in 275 patient with infiltration limited only to uterine cervix (Ib), in which Wertheim-Meigs surgery was performed. It was found invasion of many vessels- in outside of the cervix is associated with poor prognosis, no matter weather the local lymph nodes are metastatic or not and no matter what the size of the neoplastic infiltration is. Patient with severe and extensive vascular invasion require further postoperative treatment.

[Cervical cancer Ib associated with pregnancy]

An analysis of symptoms, diagnostic methods, intra- and postoperative complications in 17 pregnant patients in which Wertheim-Meigs operation was done due to stage Ib cervical cancer, is presented in this report. The most common symptoms were contact bleeding and spotting (58.8%) as well as pathologic vaginal discharge (29.4%). 3 patient did not have any symptoms in their history. No bleeding occurred in patients in whom probatory specimen was taken from their cervix. Small 7-12 days spotting appeared in 2 out of 3 patients following diagnostic conisation, done in case of ca in situ or microinvasive cancer. Pregnancy as a such was never a cause of intraoperative difficulties or complications. Mean blood transfusion was 1250 ml, this is 150 ml more than in nonpregnant patients. Most frequent postoperative complication was retentio urinare (47%). 5-year survival rate of pregnant patients (82.3%) was worse than in nonpregnant patients (96.2%) in the same age group and in comparable expansion of cancer in stage Ib in postoperative histological evaluation.

[Cervical cancer and pregnancy: prognostic value of immunological response in nodes and cancer stroma]

Immune response in the stroma of cancer and in regional lymph nodes with regard to 5-years survival rate in 17 pregnant patients in which Wertheim-Meigs operation due to Ib cervical cancer was done, is assessed in this paper. Activation and hyperplasia of T and B dependent layers of lymph nodes as well as infiltration by monocyte-macrophage and lympho-plasmatic mature, immunocompetent cells are related to good prognosis and these are most frequent in patients with small invasion. Lack of immune response in lymph nodes, its poor expression, hemolymphatic transformation, adiposis of nodes or their fibrosis was found in 5 patients; 3 of them died within 5 years. Scare monocyte-macrophage infiltrations and low-differentiated lymphocytes prevailed in the stroma of cancer. Inactive answer in nodes and in stroma was found in 8 out of 12 patients who had deeper infiltration than 0.5 cm. Immunologic response in nodes and in stroma should be assessed as a routine method for all prognostic purposes. Patients with inactive immunologic response should be qualified for further treatment.