Sudha S. Shankar

High nitric oxide production in autistic disorder: a possible role for interferon-γ

BACKGROUND Neuroimmune regulation abnormalities have been implicated in the pathophysiology of autistic disorder. Nitric oxide (NO) is involved in immune reactivity and is known to affect brain neurodevelopmental processes. Recent evidence indicates that NO, and cytokines involved in NO production, may be high in children with autism. The purpose of this study was to verify that plasma NO is high in children with autism and determine whether this elevation is related to plasma levels of cytokines involved in NO production. METHODS The metabolites of NO, nitrite, and nitrate (NOx), along with the cytokines interferon-gamma (IFN-gamma), tumor necrosis factor-alpha, and interleukin-1beta, were measured in plasma of 29 children with autism (mean age +/- SD = 6.1 +/- 2.8 years) and 27 age- and gender-matched healthy comparison subjects using commercially available assay kits. RESULTS Plasma levels of NOx were significantly higher in the autistic subjects (p =.006); plasma levels of the cytokines did not differ between groups. NOx and IFN-gamma levels were positively correlated in the autistic subjects (r =.51; p =.005). CONCLUSIONS These results confirm that plasma NO is high in some children with autism and suggest that this elevation may be related to IFN-gamma activity.

Clinical aspects of endothelial dysfunction associated with human immunodeficiency virus infection and antiretroviral agents

Endothelial dysfunction is a critical initial step of atherogenesis that subsequently contributes to the progression and clinical manifestations of atherosclerosis. The use of human immunodeficiency virus type 1 (HIV-1) protease inhibitor (PI) agents has been associated with increased cardiovascular events and worsening of multiple coronary heart disease risk factors including dyslipidemia, insulin resistance, and endothelial dysfunction. Endothelial dysfunction may be caused by HIV infection itself as well as treatment-related effects of the antiretroviral agents used to treat HIV. The available evidence suggests that Pls may induce endothelial dysfunction via their effects on both lipid and glucose metabolism. Studies in healthy subjects confirm a role for reduced endothelial nitric oxide production in the endothelial dysfunction associated with the PI indinavir. Further work is needed to determine the relative tendencies of other antiretroviral agents to induce endothelial dysfunction, the physiologic mechanisms involved, and the contribution of the metabolic and body shape changes associated with HIV treatment-related lipodystrophy, and to establish effective interventions for endothelial dysfunction in HIV-infected patients.

Treating Postprandial Hyperglycemia Does Not Appear to Delay Progression of Early Type 2 Diabetes The Early Diabetes Intervention Program

OBJECTIVE—Postprandial hyperglycemia characterizes early type 2 diabetes. We investigated whether ameliorating postprandial hyperglycemia with acarbose would prevent or delay progression of diabetes, defined as progression to frank fasting hyperglycemia, in subjects with early diabetes (fasting plasma glucose [FPG] <140 mg/dl and 2-h plasma glucose ≥200 mg/dl). RESEARCH DESIGN AND METHODS—Two hundred nineteen subjects with early diabetes were randomly assigned to 100 mg acarbose t.i.d. or identical placebo and followed for 5 years or until they reached the primary outcome (two consecutive quarterly FPG measurements of ≥140 mg/dl). Secondary outcomes included measures of glycemia (meal tolerance tests, HbA1c, annual oral glucose tolerance tests [OGTTs]), measures of insulin resistance (homeostasis model assessment [HOMA] of insulin resistance and insulin sensitivity index from hyperglycemic clamps), and secondary measures of β-cell function (HOMA-β, early- and late-phase insulin secretion, and proinsulin-to-insulin ratio). RESULTS—Acarbose significantly reduced postprandial hyperglycemia. However, there was no difference in the cumulative rate of frank fasting hyperglycemia (29% with acarbose and 34% with placebo; P = 0.65 for survival analysis). There were no significant differences between groups in OGTT values, measures of insulin resistance, or secondary measures of β-cell function. In a post hoc analysis of subjects with initial FPG <126 mg/dl, acarbose reduced the rate of development of FPG ≥126 mg/dl (27 vs. 50%; P = 0.04). CONCLUSIONS—Ameliorating postprandial hyperglycemia did not appear to delay progression of early type 2 diabetes. Factors other than postprandial hyperglycemia may be greater determinants of progression of diabetes. Alternatively, once FPG exceeds 126 mg/dl, β-cell failure may no longer be remediable.

l‐Carnitine May Attenuate Free Fatty Acid‐Induced Endothelial Dysfunction

Abstract: We have recently shown that elevated levels of free fatty acid (FFA) seen in insulin‐resistant obese subjects are associated with endothelial dysfunction. l‐Carnitine, which is required for mitochondrial FFA transport/oxidation, has been reported to improve vascular function in subjects with diabetes and heart disease. Here, we tested the hypothesis that l‐carnitine attenuates FFA‐induced endothelial dysfunction. We studied leg blood flow (LBF) responses and leg vascular resistance (LVR) to graded intrafemoral artery infusions of the endothelium‐dependent vasodilator, methacholine chloride (MCh). A group (n= 7) of normal lean subjects was studied under basal conditions (saline), after 2 h of FFA elevation (FFA), and then after 2 h of superimposing l‐carnitine on FFA elevation. FFA elevation caused the maximal LBF increment in response to MCh to decrease from 0.388 ± 0.08 to 0.212 ± 0.071 L/min (P= 0.05). Similarly, FFA blunted the maximum decrease in LVR in response to MCh from −315 ± 41 U to −105 ± 46 U (P= 0.05). The superimposed l‐carnitine restored the LBF increment in response to MCh to 0.488 ± 0.088 L/min (P= 0.05 vs. FFA) and the maximum fall in LVR to −287 ± 75 U (P= 0.05 vs. FFA), indicating that l‐carnitine elevation may attenuate FFA‐induced endothelial dysfunction. In conclusion, our data suggest that increasing l‐carnitine levels may improve FFA‐induced and obesity‐associated endothelial dysfunction. This improved endothelial function may delay or prevent the development of excess cardiovascular disease.

Changes in thrombolytic and inflammatory markers after initiation of indinavir- or amprenavir-based antiretroviral therapy

HIV-infected subjects who have lipodystrophy and insulin resistance on prolonged antiretroviral therapy have elevated levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAl-1) antigens, markers of impaired thrombolysis that are associated with hyperinsulinemia and increased cardiovascular risk. We studied HIV-infected, protease inhibitor (PI)-naive adults treated with indinavir (n=11) or amprenavir (n=14) plus two nucleoside reverse transcriptase inhibitors enrolled in two independent prospective trials. Antiretroviral and immune responses were similar in both studies. Over 8 wk, indinavir was associated with decreased insulin sensitivity, whereas amprenavir was not. Levels of tPA antigen declined by approx 25% with both treatments (p<0.05 for each); levels of PAl-1 antigen did not change. Levels of the inflammatory marker soluble tumor necrosis factor-alpha receptor II (sTNFr2) correlated positively with tPA antigen (r=0.33, p=0.02), and mean (±SD) plasma concentrations of sTNFr also declined with treatment (4.44±1.11 ng/mL pretherapy, 3.75±1.21 posttherapy, p=0.007). Short-term improvement in a marker of impaired thrombolysis and increased vascular risk can occur during PI-based antiretroviral therapy, perhaps as a consequence of improvement in HIV-related inflammation. This improvement occurred independent of development of insulin resistance, which occurred only with indivinavir.

An LC-MRM method for measuring intestinal triglyceride assembly using an oral stable isotope-labeled fat challenge.

AIM A traditional oral fatty acid challenge assesses absorption of triacylglycerol (TG) into the periphery through the intestines, but cannot distinguish the composition or source of fatty acid in the TG. Stable isotope-labeled tracers combined with LC-MRM can be used to identify and distinguish TG synthesized with dietary and stored fatty acids. RESULTS Concentrations of three abundant TGs (52:2, 54:3 and 54:4) were monitored for incorporation of one or two (2)H11-oleate molecules per TG. This method was subjected to routine assay validation and meets typical requirements for an assay to be used to support clinical studies. CONCLUSION Calculations for the fractional appearance rate of TG in plasma are presented along with the intracellular enterocyte precursor pool for 12 study participants.

Mixed Meal and Intravenous L-Arginine Tests Both Stimulate Incretin Release Across Glucose Tolerance in Man: Lack of Correlation with β Cell Function

BACKGROUND The aims of this study were to 1. define the responses of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), glucagon, and peptide YY (PYY) to an oral meal and to intravenous L-arginine; and 2. examine correlation of enteroendocrine hormones with insulin secretion. We hypothesized a relationship between circulating incretin concentrations and insulin secretion. METHODS Subjects with normal glucose tolerance (NGT, n = 23), prediabetes (PDM, n = 17), or with type 2 diabetes (T2DM, n = 22) were studied twice, following a mixed test meal (470 kCal) (mixed meal tolerance test [MMTT]) or intravenous L-arginine (arginine maximal stimulation test [AST], 5 g). GLP-1 (total and active), PYY, GIP, glucagon, and β cell function were measured before and following each stimulus. RESULTS Baseline enteroendocrine hormones differed across the glucose tolerance (GT) spectrum, T2DM generally >NGT and PDM. In response to MMTT, total and active GLP-1, GIP, glucagon, and PYY increased in all populations. The incremental area-under-the-curve (0-120 min) of analytes like total GLP-1 were often higher in T2DM compared with NGT and PDM (35-51%; P < 0.05). At baseline glucose, L-arginine increased total and active GLP-1 and glucagon concentrations in all GT populations (all P < 0.05). As expected, the MMTT and AST provoked differential glucose, insulin, and C-peptide responses across GT populations. Baseline or stimulated enteroendocrine hormone concentrations did not consistently correlate with either measure of β cell function. CONCLUSIONS/INTERPRETATION Both MMTT and AST resulted in insulin and enteroendocrine hormone responses across GT populations without consistent correlation between release of incretins and insulin, which is in line with other published research. If a defect is in the enteroendocrine/β cell axis, it is probably reduced response to rather than diminished secretion of enteroendocrine hormones.

INFLAMMATION IS INCREASED IN NON-CALCIFIED / MIXED LEFT MAIN CORONARY PLAQUES AND IS MODIFIABLE BY STATINS: A MULTI-CENTER PET-CT STUDY

Non-calcified or mixed coronary plaques without dense calcification (NCP/MP) are associated with increased atherothrombosis risk. Here we tested the hypothesis that atorvastatin (atorva) results in a reduction in left main (LM) inflammation within NCP/MP. Adults with risk factors for or with

Acute Insulin Response and β-Cell Compensation in Normal Subjects Treated With Olanzapine or Risperidone for 2 Weeks Response to Jindal

We recently reported that short-term treatment with olanzapine or risperidone did not impair acute insulin response or β-cell compensation in healthy subjects (1). Dr. Jindal (2) has cited some possible inconsistencies between our study and other reports, which we would like to address. First, Dr. Jindal notes that our conclusions contrast with those of Ader et al. (3) and points to differences in antipsychotic doses as one possible reason. However, the final olanzapine dose in our study (10 mg/day) is consistent with the package inserts target dose for patients with schizophrenia and also appears to be consistent with common prescribing practices for the treatment of schizophrenia at the time our …

64 FOUR WEEKS OF INDINAVIR DOES NOT ALTER ADIPOGENIC TRANSCRIPTION FACTORS IN HEALTHY HIV-NEGATIVE SUBJECTS.

Introduction and Purpose HIV-infected patients on antiretroviral therapy have been reported to develop a lipodystrophy syndrome. Both HIV-1 protease inhibitors, as well as nucleoside analogue reverse transcriptase inhibitors, have been implicated. However, it is unclear if this is a direct drug effect or a result of an interaction between the drug and the underlying HIV infection. In order to dissect out the direct role of drug alone in this process, we studied the in vivo effect of a single protease inhibitor, indinavir, on the key adipogenic transcription factors C/EBPa, SREBP1c, and PPARg. Methods We obtained abdominal subcutaneous adipose tissue samples from seven HIV-negative subjects at baseline and after 4 weeks of daily oral indinavir at 800 mg three times a day. Adipocytes were obtained by collagenase digestion, and total RNA was isolated by standard methods. Expression of C/EBPa, SREBP1c, and PPARg mRNA was quantitated by real time reverse transcription normalized to expression of b-actin using the delta Ct method. Results The subjects had a mean age of 36 ± 3 years, with a mean BMI of 29.5 ± 9 kg/m2. There was no change in BMI or waist-to-hip ratio after 4 weeks of indinavir. Indinavir treatment had no effect on expression of C/EBPa (304.0 ± 32.3 vs 359. 2 ± 43.4), SREBP1c (82.0 ± 14.0 vs 104.9 ± 34.0), or PPARg (350.7 ± 54.0 vs 351.0 ± 48.8 relative units). Conclusions Four weeks of the protease inhibitor indinavir does not alter adipogenic transcription factors in healthy HIV-negative subjects. Our findings indicate that indinavir does not appear to have a direct role in the development of lipodystrophy, suggesting that the lipodystrophy is likely either due to an interaction between drug and disease or attributable to antiretroviral agents other than indinavir.