Chronic Elevation Research Articles

Chronic Exposure to Palmitate Impairs Insulin Signaling in an Intestinal L-cell Line: A Possible Shift from GLP-1 to Glucagon Production.

Obesity and type 2 diabetes mellitus (T2DM) are characterized by insulin resistance and impaired glucagon-like peptide-1 (GLP-1) secretion/function. Lipotoxicity, a chronic elevation of free fatty acids in the blood, could affect insulin-signaling in many peripheral tissues. To date, the effects of lipotoxicity on the insulin receptor and insulin resistance in the intestinal L-cells need to be elucidated. Moreover, recent observations indicate that L-cells may be able to process not only GLP-1 but also glucagon from proglucagon. The aim of this study was to investigate the effects of chronic palmitate exposure on insulin pathways, GLP-1 secretion and glucagon synthesis in the GLUTag L-cell line. Cells were cultured in the presence/absence of palmitate (0.5 mM) for 24 h to mimic lipotoxicity. Palmitate treatment affected insulin-stimulated GLP-1 secretion, insulin receptor phosphorylation and IRS-1-AKT pathway signaling. In our model lipotoxicity induced extracellular signal-regulated kinase (ERK 44/42) activation both in insulin stimulated and basal conditions and also up-regulated paired box 6 (PAX6) and proglucagon expression (Gcg). Interestingly, palmitate treatment caused an increased glucagon secretion through the up-regulation of prohormone convertase 2. These results indicate that a state of insulin resistance could be responsible for secretory alterations in L-cells through the impairment of insulin-signaling pathways. Our data support the hypothesis that lipotoxicity might contribute to L-cell deregulation.

MTOR signaling mediates effects of common gamma-chain cytokines on T cell proliferation and exhaustion: implications for HIV-1 persistence and cure research.

: Chronic elevation of plasma cytokines is a key feature of HIV infection. The physiological consequences of this response to infection and its role in HIV persistence are not fully understood. Here, we show that common gamma chain (γc)-cytokines induce both proliferation and expression of T cell exhaustion markers in a mammalian target of rapamycin (mTOR)-dependent fashion, suggesting a possible therapeutic target that, if inhibited, could diminish HIV reservoir expansion, persistence, and resistance to immune surveillance.

Rho-Kinase Inhibition Reduces Myofibroblast Differentiation and Proliferation of Scleral Fibroblasts Induced by Transforming Growth Factor β and Experimental Glaucoma.

PurposeWe evaluated prevention of transforming growth factor β (TGFβ)–induced transdifferentiation of cultured scleral fibroblasts to myofibroblasts by rho-associated protein kinase (ROCK) inhibitors. Additionally, we tested whether local delivery of ROCK inhibitors reduced scleral fibroblast proliferation in response to chronic intraocular pressure (IOP) elevation.MethodsPrimary human peripapillary sclera (PPS) fibroblasts were cultured and treated with TGFβ to induce myofibroblast transdifferentiation, as determined by immunoblot assessment of α smooth muscle actin (SMA) levels and collagen gel contraction. Cells were treated with the ROCK inhibitors Y27632, fasudil, and H1152 before TGFβ treatment. ROCK activity in TGFβ-treated fibroblasts and sclera from ocular hypertensive mice was assessed by measuring phosphorylation of the ROCK substrate MYPT1 at Thr696. Fibroblast proliferation following IOP elevation and ROCK inhibitor treatment was assessed by an enzyme-linked immunosorbent (ELISA) assay.ResultsROCK inhibitors H1152 (10μM), Y27632 (10 μM), and fasudil (5μM) reduced SMA expression 72%, 85%, and 68%, respectively. Collagen gel contraction was reduced by 36% (P < 0.001), 27% (P = 0.0003), and 33% (P = 0.0019) following treatment with fasudil (25 μM), Y27632 (10 μM), and H1152 (10μM). ROCK activity induced by TGFβ rose 4.74 ± 1.9 times over control at 4 hours (P = 0.0004) and 2.4 ± 0.47-fold (P = 0.0016) in sclera after IOP elevation. Proliferation of scleral fibroblasts after chronic IOP elevation was reduced 77% by Y27632 (P = 0.001) and 84% by fasudil (P = 0.0049).ConclusionsROCK inhibitors reduce TGFβ-induced myofibroblast transdifferentiation and glaucoma-induced scleral cell proliferation.Translational RelevanceThese findings suggest altered fibroblast activity promoted by ROCK inhibitors could modify scleral biomechanics and be relevant to glaucoma treatment.

A Retrospective Review of the Diagnostic Rate of Liver Biopsy in Abnormal Liver Tests with Non-Diagnostic Serology and Biochemistry

Abnormal liver function tests, defined as values greater than 2 standard deviations above the upper limits of normal, are noted to be present in up to 7.9% of the population in the United States. In about 69% of patients, they are unexplained by current standard serology or biochemistry markers investigating common viral, autoimmune, hereditary etiologies or inborn errors of metabolism [1, 2].Liver biopsy is considered the most accurate means of grading and staging of liver disease. However, there remains some controversy over whether or not it provides overall significant information in terms of establishing an etiology which would then be used to tailor patient management. [3] Moreover, there is the established possibility of sampling error and accompanying procedure complications during liver biopsy, albeit small [3, 4]. A number of studies have suggested that a high percentage of marker negative liver biopsies had fatty infiltration of the liver with varying degrees of inflammation, with mixed reports on whether there is an association with elements of the metabolic syndrome (obesity, diabetes, dyslipidemia) and improvement with reversal of this syndrome [5, 6, 7, 8]. Several other studies have also reported significant progressive liver disease and even cirrhosis in otherwise asymptomatic patients, who were biopsied with seemingly minor chronic elevations of liver enzymes. These findings subsequently significantly impacted the patient’s care [6, 9,10]. However, these were older studies where some biochemical markers were not excluded, and had conflicting conclusions with regards to the diagnostic rate of liver biopsies. [6, 8]. With rapidly advancing imaging technology and biochemical laboratory techniques, the current study seeks to re-evaluate the utility of liver biopsy. Specifically in patients with abnormal liver tests who have had non-diagnostic biochemical or radiographic workup, the rate at which liver biopsy provides a specific diagnosis that can lead to a change to management will be studied. Keywords: Liver biopsy; Metabolic syndrome; Fatty liver disease;

Hypertonie intraoculaire retardée liée aux injections intra-vitréennes répétées d’anti-VEGF : des cas nécessitant une chirurgie filtrante

We report cases of delayed, sustained elevated intraocular pressure (IOP) associated with repeated intravitreal anti-VEGF injections (IVI), which ultimately resulted in the need for filtering surgery. Two of the three cases demonstrated severe IOP elevation despite maximal medical treatment following unilateral IVI and required urgent filtering surgery. Optic nerve involvement was severe in all three cases. These intravitreal injections were performed for exudative age-related macular degeneration (AMD), and the patients did not show any sign of glaucoma or ocular hypertension prior to the initiation of treatment. Elevated IOP secondary to intravitreal steroids is a well-known side effect, as is immediate transient IOP elevation associated with anti-VEGF injection. Late, sustained IOP elevation after repeated injections of anti-VEGF, described approximately ten years ago, is often underestimated. Its incidence is estimated between 2.1% and 13% according to studies and increases with the number of IVI (cumulative effect). The pathophysiologic process is becoming increasingly understood, and several risk factors for this chronic IOP elevation have been identified. Most often, it is a moderate IOP elevation for which topical monotherapy is sufficient, or sometimes two, three or four medications or even selective laser trabeculoplasty (SLT). However, filtering surgery may rarely be required. Our findings illustrate a little-described phenomenon: a sudden, severe, late IOP elevation in response to anti-VEGF by an "overflow" effect, requiring urgent filtering surgery.

Elevated resting blood pressure augments autonomic imbalance in posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) is characterized by increased sympathetic nervous system (SNS) activity, blunted parasympathetic nervous system (PNS) activity, and impaired baroreflex sensitivity (BRS), which contribute to accelerated cardiovascular disease. Patients with PTSD also have chronic stress-related elevations in resting blood pressure (BP), often in the prehypertensive range; yet, it is unclear if elevated resting blood pressure (ERBP) augments these autonomic derangements in PTSD. We hypothesized that compared with normotensive PTSD (N-PTSD), those with ERBP (E-PTSD) have further increased SNS, decreased PNS activity, and impaired BRS at rest and exaggerated SNS reactivity, PNS withdrawal, and pressor responses during stress. In 16 E-PTSD and 17 matched N-PTSD, we measured continuous BP, ECG, muscle sympathetic nerve activity (MSNA), and heart rate variability (HRV) markers reflecting cardiac PNS activity [standard deviation of R-R intervals (SDNN), root mean square of differences in successive R-R intervals (RMSSD), and high frequency power (HF)] during 5 min of rest and 3 min of mental arithmetic. Resting MSNA ( P = 0.943), sympathetic BRS ( P = 0.189), and cardiovagal BRS ( P = 0.332) were similar between groups. However, baseline SDNN (56 ± 6 vs. 78 ± 8 ms, P = 0.019), RMSSD (39 ± 6 vs. 63 ± 9 ms, P = 0.018), and HF (378 ± 103 vs. 693 ± 92 ms2, P = 0.015) were lower in E-PTSD versus N-PTSD. During mental stress, the systolic blood pressure response ( P = 0.011) was augmented in E-PTSD. Although MSNA reactivity was not different ( P > 0.05), the E-PTSD group had an exaggerated reduction in HRV during mental stress ( P < 0.05). PTSD with ERBP have attenuated resting cardiac PNS activity, coupled with exaggerated BP reactivity and PNS withdrawal during stress.

Approach to the Liver Biopsy in the Patient With Chronic Low-Level Aminotransferase Elevations.

Pathologists sometimes encounter a liver biopsy from an asymptomatic patient with unexplained low-level parenchymal liver enzyme elevations. These biopsies often have minor histologic changes but are otherwise almost entirely normal. This can lead to the quandary of whether or not the features are clinically meaningful and how one must formulate a diagnosis from the possibly nonspecific findings of a near-normal biopsy. The following discussion focuses on the histologic changes that can be seen in these biopsies and the practical issues involved in making a diagnosis that provides useful information to the clinician. The literature and textbooks addressing the histologic and clinical features of these cases are reviewed with an emphasis on the clinical implications of finding nonspecific histologic alterations in these patients.

Transcriptional Regulation of Lipophorin Receptors Supports Neuronal Adaptation to Chronic Elevations of Activity

SUMMARYActivity-dependent modifications strongly influence neural development. However, molecular programs underlying their context and circuit-specific effects are not well understood. To study global transcriptional changes associated with chronic elevation of synaptic activity, we performed cell-type-specific transcriptome profiling of Drosophila ventral lateral neurons (LNvs) in the developing visual circuit and identified activity-modified transcripts that are enriched in neuron morphogenesis, circadian regulation, and lipid metabolism and trafficking. Using bioinformatics and genetic analyses, we validated activity-induced isoform-specific upregulation of Drosophila lipophorin receptors LpR1 and LpR2, the homologs of mammalian low-density lipoprotein receptor (LDLR) family proteins. Furthermore, our morphological and physiological studies uncovered critical functions of neuronal lipophorin receptors (LpRs) in maintaining the structural and functional integrities in neurons challenged by chronic elevations of activity. Together, our findings identify LpRs as molecular targets for activity-dependent transcriptional regulation and reveal the functional significance of cell-type-specific regulation of neuronal lipid uptake in experience-dependent plasticity and adaptive responses.

HIGH SENSITIVITY TROPONIN AND BRAIN-TYPE NATRIURETIC PEPTIDE FLUCTUATION DURING HEMODIALYSIS AND THEIR POTENTIAL CLINICAL APPLICATION ON CARDIOVASCULAR PROGNOSIS

Chronic elevation of high sensitivity troponin (hs-cTnT) and Brain-type natriuretic peptide (Nt-pro-BNP) in end-stage renal disease is associated with worse cardiovascular outcomes, including in hemodialysis (HD) setting. Studies have attempted to correlate variation of those biomarkers over time to cardiovascular prognosis but little is known about how HD parameters acutely influence those biomarkers. To determine the relationship between Nt-pro-BNP and hs-cTnT with HD parameters, 50 participants that were on HD for at least a month were enrolled on the HD ward at our institution. Exclusion criteria were designed to exclude any potential alternative source of hs-cTnT and Nt-pro-BNP elevation (eg. recent myocardial infarction or heart failure, Ejection fraction < 40% (…) ). Among those approached, eight patients were excluded. Six consecutive serum samples were analysed for hs-cTnT and Nt-pro-BNP before and after HD. Hs-cTnT and Nt-pro-BNP percentage decrease after HD were individually analysed in respect with HD weight reduction percentage, ultrafiltration rate, Kt/V (HD adequacy parameter) presence of diastolic dysfunction, indexed left ventricular mass, peri-dialysis hypotension, blood filtration rate and with the other biomarker. Linear regression analysis was used in a fixed-effect model for multivariate assessment and pearson coefficient was calculated for association between the variation of the two biomarkers. Mean decrease after dialysis for hs-cTnT was 38,3% ± 3,9% and for Nt-pro-BNP was 56,1% ± 3,5%. Pearson’s correlation coefficient was of 0,646 (p<0.001) between the decrease of Hs-cTnT and Nt-pro-BNP. Nt-pro-BNP percentage fluctuated with a R2 coefficient of 0,53 with our model. Standardised significant β coefficient were the following: troponin percentage decrease: 0,570 (p<0,001), ultrafiltration rate: -0,558 (p=0,001), weight decrease percentage: 0,399 (p=0,020). Mean absolute and average changes of the two biomarkers following each HD session is shown in table 1. Hs-cTnT and Nt-pro-BNP are diminished after HD in a manner that is reproducible for the same patient and their change is interrelated. Factors that decrease Nt-pro-BNP are higher quantity of fluid removal during HD and lower ultrafiltration rates. Since elevated levels of those biomarkers correlate with increased mortality, strategies to decrease their level by adjusting hemodialysis parameters (increasing fluid removal and lowering ultrafiltration rate) could be evaluated in further studies to improve cardiovascular prognosis in patients undergoing HD.

Stargazin Dephosphorylation Mediates Homeostatic Synaptic Downscaling of Excitatory Synapses.

Synaptic scaling is a form of homeostatic plasticity that is critical for maintaining neuronal activity within a dynamic range, and which alters synaptic strength through changes in postsynaptic AMPA-type glutamate receptors. Homeostatic scaling down of excitatory synapses has been shown to occur during sleep, and to contribute to synapse remodeling and memory consolidation, but the underlying mechanisms are only partially known. Here, we report that synaptic downscaling in cortical neurons is accompanied by dephosphorylation of the transmembrane AMPA receptor regulatory protein stargazin, and by an increase in its cell surface mobility. The changes in stargazin surface diffusion were paralleled by an increase in the mobility of GluA1-containing AMPA receptors at synaptic sites. In addition, stargazin dephosphorylation was required for the downregulation of surface levels of GluA1-containing AMPA receptors promoted by chronic elevation of neuronal activity, specifically by mediating the interaction with the adaptor proteins AP-2 and AP-3A. Disruption of the stargazin-AP-3A interaction was sufficient to prevent the decrease in cell surface GluA1-AMPA receptor levels associated with chronically enhanced synaptic activity, suggesting that scaling down is accomplished through decreased AMPA receptor recycling and enhanced lysosomal degradation. Thus, synaptic downscaling is associated with both increased stargazin and AMPA receptor cell surface diffusion, as well as with stargazin-mediated AMPA receptor endocytosis and lysosomal degradation.

Late and sustained intraocular pressure elevation related to intravitreal anti-VEGF injections: Cases requiring filtering surgery

We report cases of delayed, sustained elevated intraocular pressure (IOP) associated with repeated intravitreal anti-VEGF injections (IVI), which ultimately resulted in the need for filtering surgery. Two of the three cases demonstrated severe IOP elevation despite maximal medical treatment following unilateral IVI and required urgent filtering surgery. Optic nerve involvement was severe in all three cases. These intravitreal injections were performed for exudative age-related macular degeneration (AMD), and the patients did not show any sign of glaucoma or ocular hypertension prior to the initiation of treatment. Elevated IOP secondary to intravitreal steroids is a well-known side effect, as is immediate transient IOP elevation associated with anti-VEGF injection. Late, sustained IOP elevation after repeated injections of anti-VEGF, described approximately ten years ago, is often underestimated. Its incidence is estimated between 2.1 % and 13 % according to studies and increases with the number of IVI (cumulative effect). The pathophysiologic process is becoming increasingly understood, and several risk factors for this chronic IOP elevation have been identified. Most often, it is a moderate IOP elevation for which topical monotherapy is sufficient, or sometimes two, three or four medications or even selective laser trabeculoplasty (SLT). However, filtering surgery may rarely be required. Our findings illustrate a little-described phenomenon: a sudden, severe, late IOP elevation in response to anti-VEGF by an "overflow" effect, requiring urgent filtering surgery.

Epilepsy-predictive magnetic resonance imaging changes following experimental febrile status epilepticus: Are they translatable to the clinic?

A subset of children with febrile status epilepticus (FSE) are at risk for development of temporal lobe epilepsy later in life. We sought a noninvasive predictive marker of those at risk that can be identified soon after FSE, within a clinically realistic timeframe. Longitudinal T2 -weighted magnetic resonance imaging (T2 WI MRI) of rat pups at several time points after experimental FSE (eFSE) was performed on a high-field scanner followed by long-term continuous electroencephalography. In parallel, T2 WI MRI scans were performed on a 3.0-T clinical scanner. Finally, chronic T2 WI MRI signal changes were examined in rats that experienced eFSE and were imaged months later in adulthood. Epilepsy-predicting T2 changes, previously observed at 2hours after eFSE, persisted for at least 6hours, enabling translation to the clinic. Repeated scans, creating MRI trajectories of T2 relaxation times following eFSE, provided improved prediction of epileptogenesis compared with a single MRI scan. Predictive signal changes centered on limbic structures, such as the basolateral and medial amygdala. T2 WI MRI changes, originally described on high-field scanners, can also be measured on clinical MRI scanners. Chronically elevated T2 relaxation times in hippocampus were observed months after eFSE in rats, as noted for post-FSE changes in children. Early T2 WI MRI changes after eFSE provide a strong predictive measure of epileptogenesis following eFSE, on both high-field and clinical MRI scanners. Importantly, the extension of the acute signal changes to at least 6hours after the FSE enables its inclusion in clinical studies. Chronic elevations of T2 relaxation times within the hippocampal formation and related structures are common to human and rodent FSE, suggesting that similar processes are involved across species.

Type 2 Diabetes Mellitus Risk Level, Cardiovascular Diseases Risk Level, and Quality of Work Life among University Staffs; Correlational study

Type 2 diabetes mellitus and cardiovascular diseases are two of the most serious health problems produce wide negative impacts in Indonesia. Both diseases shares similar risks factors and may affect individual’s health status and quality of work (QoWL). Unfortunately, there is no evidence reported the chronic diseases risk level and their correlation with QoWL among university staffs in Indonesia. This correlational study aimed to identify the risk level of Type 2 diabetes mellitus (T2DM) and cardiovascular diseases and it correlation with the QoWL among university staffs. As many as 125 university staffs from one of public university in West Java – Indonesia were recruited randomly and asked to complete Finnish Diabetes Risk-Assessment form, The Jakarta Cardiovascular Scale, and quality of work life (QoWL) Evaluation Scale. The collected data were analyzed using descriptive and Pearson Correlation test. Results showed that nearly half of respondents had chronic diseases risk elevation; T2DM (40.39) and cardiovascular diseases (49%). Additionally, more than half of them (52.40%) perceived that their QoWL was less satisfied. It was found there was a significant relationship between T2DM risk level and cardiovascular diseases risk (r = 0.513; p=0.00); however, there was no significant correlation, neither between T2DM risk level (p=0.54) nore cardiovascular disease risk level (p = 0.19) with QoWL. To summarize, the university staffs are vulnerable for developing chronic diseases and have less satisfied QoWL. Therefore, it is important for the university to develop policy or program that enhances the employees’ opportunity in managing the risk and improving their health status and QoWL.

Serum Uric Acid Elevation is Associated to Arterial Stiffness in Hypertensive Patients with Metabolic Disturbances.

Chronic serum uric acid elevation (SUA) is known to be induced by dyslipidemia, hypertension, inflammation, and insulin resistance. Therefore, it has been associated with higher risk for coronary artery disease and cardiovascular mortality. Also, increased levels of SUA have been associated with regional arterial stiffness, assessed by pulse wave velocity (PWV). To evaluate the relationships of PWV, SUA and different metabolic parameters in essential hypertensive patients. We evaluated 445 essential hypertensive patients, by measuring office blood pressure (BP), weight, height, and waist circumference. In each patient, blood samples were drawn for biochemical evaluations and 24h urine collection. Body Mass Index (BMI) and Glomerular Filtration Rate (GFR) were calculated. Carotid-Femoral PWV and Left Ventricular Mass Index (LVMI) were measured in all patients. All subjects (n=402), 242 males (55±0.9 yrs.; BMI: 28.9±0.3 Kg/m2) and 160 females (58±1 yrs.; BMI: 28.1±0.4 Kg/m2) had normal renal function. PWV values showed a significant association with SUA (p<0.001), Systolic BP (p<0.025) and LVMI (p<0.05). SUA showed a significant association, p<0.025: with BMI, Waist Circumference, and HDL-C; p<0.05: with Glycaemia at 120 min, Insulin at 120 min, TG, and LVMI; and p<0.001: with serum Creatinine. Backward Stepwise Regression showed that PWV could be predicted from SUA (p<0.001) and Systolic BP (p<0.05). BMI, Waist Circumference, DBP and HR did not significantly add to the ability of the equation to predict PWV. In this population of essential hypertensive patients, SUA was associated to increased arterial stiffness and to components of the Metabolic Syndrome. These results raise the possibility that a new approach to the role of SUA, linked to cardiovascular stratification, and a most appropriate treatment might be considered.

Chronic in vivo angiotensin II administration differentially modulates the slow delayed rectifier channels in atrial and ventricular myocytes

In the heart, slow delayed rectifier channels provide outward currents (IKs) for action potential (AP) repolarization in a region- and context-dependent manner. In diseased hearts, chronic elevation of angiotensin II (Ang II) may remodel IKs in a region-dependent manner, contributing to atrial and ventricular arrhythmias of different mechanisms. The purpose of this study was to study whether/how chronic invivo Ang II administration remodels IKs in atrial and ventricular myocytes. We used the guinea pig (GP) model whose myocytes express robust IKs. GPs were implanted with minipumps containing Ang II or vehicle. Treatment continued for 4-6 weeks. We used patch clamp, immunofluorescence/confocal microscopy, and immunoblots to evaluate changes in IKs function and to explore the underlying mechanisms. We confirmed the pathologic state of the heart after chronic Ang II treatment. IKs density was increased in atrial myocytes but decreased in ventricular myocytes in Ang II- vs vehicle-treated animals. The former was correlated with an increase in KCNQ1/KCNE1 colocalization in myocyte periphery, whereas thelatter was correlated with a decrease in KCNQ1 protein level. Interestingly, these changes in IKs were not translated into expected alterations in AP duration or plateau voltage, indicating that other currents were involved. In atrial myocytes from Ang II-treated animals, the L-type Ca channel current was increased, contributing to AP plateau elevation and AP duration prolongation. IKs is differentially modulated by chronic invivo AngII administration between atrial and ventricular myocytes. Other currents remodeled by Ang II treatment also contribute to changes in action potentials.

Chronic d-serine supplementation impairs insulin secretion

ObjectiveThe metabolic role of d-serine, a non-proteinogenic NMDA receptor co-agonist, is poorly understood. Conversely, inhibition of pancreatic NMDA receptors as well as loss of the d-serine producing enzyme serine racemase have been shown to modulate insulin secretion. Thus, we aim to study the impact of chronic and acute d-serine supplementation on insulin secretion and other parameters of glucose homeostasis. MethodsWe apply MALDI FT-ICR mass spectrometry imaging, NMR based metabolomics, 16s rRNA gene sequencing of gut microbiota in combination with a detailed physiological characterization to unravel the metabolic action of d-serine in mice acutely and chronically treated with 1% d-serine in drinking water in combination with either chow or high fat diet feeding. Moreover, we identify SNPs in SRR, the enzyme converting L-to d-serine and two subunits of the NMDA receptor to associate with insulin secretion in humans, based on the analysis of 2760 non-diabetic Caucasian individuals. ResultsWe show that chronic elevation of d-serine results in reduced high fat diet intake. In addition, d-serine leads to diet-independent hyperglycemia due to blunted insulin secretion from pancreatic beta cells. Inhibition of alpha 2-adrenergic receptors rapidly restores glycemia and glucose tolerance in d-serine supplemented mice. Moreover, we show that single nucleotide polymorphisms (SNPs) in SRR as well as in individual NMDAR subunits are associated with insulin secretion in humans. ConclusionThus, we identify a novel role of d-serine in regulating systemic glucose metabolism through modulating insulin secretion.

Contribution of autophagy to ocular hypertension and neurodegeneration in the DBA/2J spontaneous glaucoma mouse model

Glaucoma is a progressive optic neuropathy characterized by axonal degeneration and retinal ganglion cells loss. Several factors have been postulated to play a role in glaucoma, elevated intraocular pressure (IOP) being the best well-known causative factor. The mechanisms leading to ocular hypertension and glaucoma are still not fully understood. An increasing number of evidence indicates a role of autophagy in the pathophysiological process of ocular hypertension and glaucoma. However, while all of the studies agree that autophagy is induced in RGCs in response to injury, autophagy was found to either protect or promote cell death depending on the experimental model used. In order to gain more insight into both, the role of autophagy in the pathogenesis of glaucoma and the effect of chronic IOP elevation in the autophagy pathway, we have investigated here for the first time autophagy in the iridocorneal angle region, retinal ganglion cell bodies, and ON axons in the spontaneous ocular hypertensive DBA/2J mouse glaucoma model and in the transgenic DBA/2J::GFP-LC3 mice, generated in our laboratory. Our results indicate decreased autophagic flux in the outflow pathway cells in the DBA/2J mice, characterized by increased levels of LC3-II and p62 together with a decrease in the lysosomal marker LAMP1, evaluated by western blot and immunofluorescence. Elevated presence of autophagic vacuoles in the DBA/2J and, in particular, in the DBA/2J::GFP-LC3 mice was also observed. Expression of the GFP-LC3 transgene was associated to higher cumulative IOP in the DBA/2J background. In addition to higher elevation in IOP, DBA/2J::GFP-LC3 were characterized by further RGCs and exacerbated axonal degeneration compared to DBA/2J. This was accompanied by the notable high presence of autophagic figures within degenerating axons. These results strongly suggest overactivation of autophagy as a potential cellular mechanism leading to ON degeneration in the chronic hypertensive DBA/2J mice.

Erythropoietin stimulates fibroblast growth factor 23 (FGF23) in mice and men.

Fibroblast growth factor 23 (FGF23) is a major endocrine regulator of phosphate and 1,25 (OH)2 vitamin D3 metabolism and is mainly produced by osteocytes. Its production is upregulated by a variety of factors including 1,25 (OH)2 vitamin D3, high dietary phosphate intake, and parathyroid hormone (PTH). Recently, iron deficiency and hypoxia have been suggested as additional regulators of FGF23 and a role of erythropoietin (EPO) was shown. However, the regulation of FGF23 by EPO and the impact on phosphate and 1,25(OH)2 vitamin D3 are not completely understood. Here, we demonstrate that acute administration of recombinant human EPO (rhEPO) to healthy humans increases the C-terminal fragment of FGF23 (C-terminal FGF23) but not intact FGF23 (iFGF23). In mice, rhEPO stimulates acutely (24h) C-terminal FGF23 but iFGF23 only after 4days without effects on PTH and plasma phosphate. 1,25 (OH)2 D3 levels and αklotho expression in the kidney decrease after 4days. rhEPO induced FGF23 mRNA in bone marrow but not in bone, with increased staining of FGF23 in CD71+ erythroid precursors in bone marrow. Chronic elevation of EPO in transgenic mice increases iFGF23. Finally, acute injections of recombinant FGF23 reduced renal EPO mRNA expression. Our data demonstrate stimulation of FGF23 levels in mice which impacts mostly on 1,25 (OH)2 vitamin D3 levels and metabolism. In humans, EPO is mostly associated with the C-terminal fragment of FGF23; in mice, EPO has a time-dependent effect on both FGF23 forms. EPO and FGF23 may form a feedback loop controlling and linking erythropoiesis and mineral metabolism.

PO-063 Pre-diagnostic unconjugated bilirubin levels and colorectal cancer risk in the european prospective investigation into cancer and nutrition (EPIC)

IntroductionUnconjugated Bilirubin (UCB), the end product of heme catabolism, is a powerful antioxidant. A mild chronic elevation of circulating UCB, known as Gilbert’s Syndrome (GS), is a relatively common condition affecting 5%–10% (depending on ethnicity and gender) of the adult population. Individuals with endogenously elevated UCB appear to be at lower risk of developing certain diseases where oxidative stress has been implicated in the disease process, such as cancer.Material and methodsWe investigated the association between pre-diagnostic plasma UCB concentrations and risk of colorectal cancer (CRC) development in a case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, a multicenter prospective study carried out in 23 centres from 10 European countries including 5 19 978 participants.Plasma UCB was measured by High Performance Liquid Chromatography (HPLC) in 1387 cases and 1387 controls matched on age, centre, follow-up time, time of blood collection, fasting status and menopausal status in women.Odds ratios (OR) and 95% confidence intervals (CI) for CRC risk were estimated using multivariable conditional logistic regression models stratified by sex, which were adjusted for potential confounders. UCB was Log2- transformed when used as a continuous variable to improve linearity.Results and discussionsIn a multivariable model that included potential confounding factors, higher Log2- transformed UCB, corresponding to a doubling of UCB concentration, was associated with increased CRC risk in men (OR=1.27; 95% CI: 1.05,1.52; p=0.01) whereas an inverse association with CRC risk was observed in women (OR=0.83; 95% CI: 0.70,0.99; p=0.04).ConclusionThese results suggest that higher levels of circulating UCB may confer protection against CRC in women but may elevate risk in men. Additional studies are necessary to confirm these findings and to further investigate potential underlying mechanisms for the role of circulating UCB in CRC development.

A murine glaucoma model induced by rapid in vivo photopolymerization of hyaluronic acid glycidyl methacrylate.

Glaucoma is an optic neuropathy commonly associated with elevated intraocular pressure (IOP) resulting in progressive loss of retinal ganglion cells (RGCs) and optic nerve degeneration, leading to blindness. New therapeutic approaches that better preserve the visual field by promoting survival and health of RGCs are highly needed since RGC death occurs despite good IOP control in glaucoma patients. We have developed a novel approach to reliably induce chronic IOP elevation in mouse using a photopolymerizable biomatrix, hyaluronic acid glycidyl methacrylate. This is achieved by rapid in vivo crosslinking of the biomatrix at the iridocorneal angle by a flash of ultraviolet A (UVA) light to impede the aqueous outflow pathway with a controllable manner. Sustained IOP elevation was induced after a single manipulation and was maintained at ~45% above baseline for >4 weeks. Significant thinning of the inner retina and ~35% reduction in RGCs and axons was noted within one month of IOP elevation. Optic nerve degeneration showed positive correlation with cumulative IOP elevation. Activation of astrocytes and microglia appeared to be an early event in response to IOP elevation preceding detectable RGC and axon loss. Attenuated glial reactivity was noted at later stage where significant RGC/axon loss had occurred suggesting astrocytes and microglia may play different roles over the course of glaucomatous degeneration. This novel murine glaucoma model is reproducible and displays cellular changes that recapitulate several pathophysiological features of glaucoma.