Stanley F. Fernandez

Morphine Exacerbates HIV-1 Viral Protein gp120 Induced Modulation of Chemokine Gene Expression in U373 Astrocytoma Cells

HIV-1 affects microglia and astroglia, which subsequently contributes to the neurodegenerative changes. Viral proteins cause neurotoxicity by direct action on the CNS cells or by activating glial cells to cause the release of cytokines, chemokines or neurotoxic substances. Opioid abuse has been postulated as a cofactor in the immunopathogenesis of human immunodeficiency virus (HIV) infection and AIDS. HIV-induced pathogenesis is exacerbated by opiate abuse and that the synergistic neurotoxicity is a direct effect of opiates on the CNS. Chemokines and their receptors have been implicated in the pathogenesis of neuroAIDS. Herein we describe the effects of morphine and/or gp120 on the expression of the genes for the beta-chemokine MIP-1beta and its receptors CCR3 and CCR5 by the U373 cells which are a human brain-derived astrocytoma/glioblastoma cell line. Our results indicate that treatment of U373 cells with morphine significantly downregulated the gene expression of the beta chemokine, MIP-1 beta, while reciprocally upregulating the expression of its specific receptors, CCR3 and CCR5 suggesting that the capacity of mu-opioids to increase HIV-1 co-receptor expression may promote viral binding, trafficking of HIV-1-infected cells, and enhanced disease progression. Additionally, opiates can enhance the cytotoxicity of HIV-1 viral protein gp120 via mechanisms that involve intracellular calcium modulation resulting in direct actions on astroglia, making them an important cellular target for HIV-opiate interactions.

Tight Junction Regulation by Morphine and HIV-1 Tat Modulates Blood–Brain Barrier Permeability

Human immunodeficiency virus (HIV)-1 patients who abuse opiates are at a greater risk of developing neurological complications of AIDS. Alterations in blood–brain barrier (BBB) integrity are associated with cytoskeletal disorganization and disruption of tight junction (TJ) integrity. We hypothesize that opiates in combination with HIV-1 viral proteins can modulate TJ expression in primary brain microvascular endothelial cells (BMVEC), thereby compromising BBB integrity and exacerbating HIV-1 neuropathogenesis. We investigated the effect of morphine and/or tat on the expression of TJ proteins ZO-1, JAM-2, Occludin and P-glycoprotein and the functional effects of TJ modulation in BMVEC. Morphine and/or tat, via the activation of pro-inflammatory cytokines, intracellular Ca2+ release, and activation of myosin light chain kinase, modulated TJ expression resulting in decreased transendothelial electric resistance and enhanced transendothelial migration across the BBB. These studies may lead to the development of novel anti-HIV-1 therapeutics that target specific TJ proteins, thus preventing TJ disruption in opiate using HIV-1 patients.

Modulation of Angiotensin II Responses in Sympathetic Neurons by Cytosolic Calcium

Abstract—Both stimulatory and suppressive responses of the sympathetic nervous system to angiotensin II (AII) have been reported in intact animals. To elucidate possible cellular mechanisms, we studied AII-induced changes in cytosolic Ca2+ ([Ca2+]i) in primary cultures of rat stellate ganglion neurons. Two different patterns of [Ca2+]i responses to AII were observed: dose-dependent increases in [Ca2+]i in cells with intrinsically low baseline [Ca2+]i (n=64) and dose-dependent suppression of [Ca2+]i in neurons with intrinsically higher baseline [Ca2+]i (n=46). Individual neurons could express both response patterns to AII. In neurons with low basal [Ca2+]i, superfusion with Ca2+ ionophore (ionomycin) increased [Ca2+]i and reversed the initial AII-induced stimulatory pattern. L-type Ca2+ channel antagonism (nifedipine) in neurons with high baseline [Ca2+]i lowered [Ca2+]i and reversed the initial AII-induced suppressive response. Both stimulatory and suppressive responses were abolished by AT1 receptor antagonism (losartan). AII-induced stimulatory responses were blocked by IP3 receptor antagonism (2-APB) and by thapsigargin. AII-induced suppression of neuronal [Ca2+]i was blunted when Na-Ca exchange was impaired. We conclude that [Ca2+]i acts as a switch for AII-mediated stimulatory and suppressive responses in individual sympathetic neurons. AT1 receptor-mediated neuronal stimulation and suppression may allow local homeostatic adaptation to meet complex systemic needs.

Emerging medical treatment for angina pectoris

Importance of the field: Despite improved mortality and morbidity in the treatment of coronary artery disease, a significant proportion of patients will continue to experience recurrent angina pectoris. Areas covered in this review: Anti-anginal therapy has long been dominated by the use of β-blockers, Ca2+ channel blockers and nitrates. Most recently, ranolazine was introduced as a new anti-anginal class. This review article presents current and novel anti-anginal strategies under development. A discussion of their molecular mechanisms that may complement traditional therapies is presented. Medline and PubMed scientific search tools were primarily used to identify relevant literature dating from 1970 to 2008. What the reader will gain: This review provides a summary of both traditional and emerging therapeutic approaches to angina pectoris management. A discussion on the mechanism of action and clinical efficacy of ranolazine, trimetazidine, nicorandil, ivabradine, fasudil and growth factor gene therapy as anti-anginal agents is provided. Take home message: The need for multiple approaches cannot be over-emphasized. Availability of various modalities would strongly enhance the ability to meet the needs of a heterogeneous patient population. Patients with recurrent angina pectoris most likely will require multi-drug regimen where different mechanisms may complement each other and result in a more efficacious strategy.

Hibernating Myocardium Results in Partial Sympathetic Denervation and Nerve Sprouting

Hibernating myocardium due to chronic repetitive ischemia is associated with regional sympathetic nerve dysfunction and spontaneous arrhythmic death in the absence of infarction. Although inhomogeneity in regional sympathetic innervation is an acknowledged substrate for sudden death, the mechanism(s) responsible for these abnormalities in viable, dysfunctional myocardium (i.e., neural stunning vs. sympathetic denervation) and their association with nerve sprouting are unknown. Accordingly, markers of sympathetic nerve function and nerve sprouting were assessed in subendocardial tissue collected from chronically instrumented pigs with hibernating myocardium (n = 18) as well as sham-instrumented controls (n = 7). Hibernating myocardium exhibited evidence of partial sympathetic denervation compared with the normally perfused region and sham controls, with corresponding regional reductions in tyrosine hydroxylase protein (-32%, P < 0.001), norepinephrine uptake transport protein (-25%, P = 0.01), and tissue norepinephrine content (-45%, P < 0.001). Partial denervation induced nerve sprouting with regional increases in nerve growth factor precursor protein (31%, P = 0.01) and growth associated protein-43 (38%, P < 0.05). All of the changes in sympathetic nerve markers were similar in animals that developed sudden death (n = 9) compared with electively terminated pigs with hibernating myocardium (n = 9). In conclusion, sympathetic nerve dysfunction in hibernating myocardium is most consistent with partial sympathetic denervation and is associated with regional nerve sprouting. The extent of sympathetic remodeling is similar in animals that develop sudden death compared with survivors; this suggests that sympathetic remodeling in hibernating myocardium is not an independent trigger for sudden death. Nevertheless, sympathetic remodeling likely contributes to electrical instability in combination with other factors.

Takotsubo Cardiomyopathy Following Initial Chemotherapy Presenting with Syncope and Cardiogenic Shock - a Case Report and Literature Review

Takotsubo cardiomyopathy (TC) is an uncommon acute syndrome that mimics ST-segment elevation myocardial infarction. It is characterized by dynamic electrocardiographic changes associated with transient, severe left ventricular wall motion abnormalities not attributable to obstructive epicardial coronary disease in a pattern that involves the mid and apical segments of the heart in all coronary distributions. It is typically felt to be precipitated by emotional or physical stress and more common in elderly women than men. Here we report a case of TC presenting as syncope and cardiogenic shock five days following an initial course of chemo-immunotherapy that included treatment with liposomal doxorubicin and with clinical and imaging features consistent with TC.

Mechanisms of Angiotensin II–Mediated Decreases in Intraneuronal Ca2+ in Calcium-Loaded Stellate Ganglion Neurons

Our laboratory has reported previously that angiotensin II, type-1 (AT1) receptor stimulation in isolated stellate ganglion neurons decreases intraneuronal calcium concentration ([Ca2+]i) acutely if baseline [Ca2+]i is high and increases [Ca2+]i if baseline [Ca2+]i is low. Part of the angiotensin II (Ang II) effect in high Ca2+ neurons is mediated through stimulation of Na+–Ca2+ exchange. Current experiments were conducted to identify additional steps in the signaling pathways. In Ca2+-loaded neurons, Ang II–induced decreases in [Ca2+]i were attenuated by phospholipase C inhibition (U73122) or nitric oxide (NO) synthase inhibition (l-NMMA) and were mimicked by the cGMP analogue 8-Br-cGMP. Protein kinase C (PKC) inhibition (bisindolylmaleimide I or Go6976) and protein kinase G (PKG) inhibition (KT5823) partially blocked Ang II–mediated decreases in [Ca2+]i, but complete blockade of Ang II effects was obtained with combined PKC and PKG inhibition. Modulation of inositol triphosphate (IP3)-inducible ER Ca2+ release by [Ca2+]i was investigated using furaptra, an ER-retaining dye. IP3-mediated ER Ca2+ release in &bgr;-escin–permeabilized neurons was measured after clamping of [Ca2+]i from 50 nM to 800 nM. Maximal ER Ca2+ release was observed at ≈200 nM [Ca2+]i, with noted blunting of release at higher [Ca2+]i. Steady-state mRNA transcript and protein levels revealed that the principal IP3R isoform expressed was IP3R-II. These results suggest that Ca2+ loading in stellate ganglion neurons promotes Ang II-mediated decreases in [Ca2+]i via PKC and NO/cGMP/PKG pathways and inhibits IP3R-II–mediated ER Ca2+ release.

Prognostic Significance of Imaging Myocardial Sympathetic Innervation.

There has been a longstanding interest in understanding whether the presence of inhomogeneity in myocardial sympathetic innervation can predict patients at risk of sudden cardiac arrest from lethal ventricular arrhythmias. The advent of radiolabeled norepinephrine analogs has allowed this to be imaged in patients with ischemic and non-ischemic cardiomyopathy using single, photon emission computed tomography (SPECT) and positron emission tomography (PET). Several observational studies have demonstrated that globally elevated myocardial sympathetic tone (as reflected by reduced myocardial norepinephrine analog uptake) can predict composite cardiac end-points including total cardiovascular mortality. More recent studies have indicated that quantifying the extent of regional denervation can predict the risk of lethal ventricular arrhythmias and sudden cardiac death. This review will summarize our current understanding of the prognostic significance of altered myocardial sympathetic innervation.

Low pH Environmental Stress Inhibits LPS and LTA-Stimulated Proinflammatory Cytokine Production in Rat Alveolar Macrophages

Gastric aspiration increases the risks for developing secondary bacterial pneumonia. Cytokine elaboration through pathogen recognition receptors (PRRs) is an important mechanism in initiating innate immune host response. Effects of low pH stress, a critical component of aspiration pathogenesis, on the PRR pathways were examined, specifically toll-like receptor-2 (TLR2) and TLR4, using isolated rat alveolar macrophages (aMØs). We assessed the ability of aMØs after brief exposure to acidified saline to elaborate proinflammatory cytokines in response to lipopolysaccharide (LPS) and lipoteichoic acid (LTA) stimulation, known ligands of TLR4 and TLR2, respectively. Low pH stress reduced LPS- and LTA-mediated cytokine release (CINC-1, MIP-2, TNF-α, MCP-1, and IFN-β). LPS and LTA increased intracellular Ca2+ concentrations while Ca2+ chelation by BAPTA decreased LPS- and LTA-mediated cytokine responses. BAPTA blocked the effects of low pH stress on most of LPS-stimulated cytokines but not of LTA-stimulated responses. In vivo mouse model demonstrates suppressed E. coli and S. pneumoniae clearance following acid aspiration. In conclusion, low pH stress inhibits antibacterial cytokine response of aMØs due to impaired TLR2 (MyD88 pathway) and TLR4 signaling (MyD88 and TRIF pathways). The role of Ca2+ in low pH stress-induced signaling is complex but appears to be distinct between LPS- and LTA-mediated responses.

Strategies in Stable Ischemic Heart Disease: Lessons from the COURAGE and BARI-2D Trials

There is a continuing debate regarding the most effective strategy for treating stable ischemic heart disease (SIHD). Conflicting data have emerged from several small, randomized controlled trials and meta-analyses regarding the benefits of early revascularization in SIHD. Two recent multicenter, randomized trials, the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial and the Bypass Angioplasty Revascularization Investigation in Type 2 Diabetes (BARI-2D) trial, compared two management strategies in SIHD—an initial conservative approach with optimal medical therapy (OMT) versus a strategy of early revascularization in combination with OMT. COURAGE randomized SIHD patients who were candidates for percutaneous coronary intervention (PCI) to either a strategy of early PCI in combination with OMT or OMT alone, whereas BARI-2D randomized diabetic patients with coronary artery disease to either early revascularization (PCI or coronary artery bypass surgery [CABG]) versus OMT. This review examines the principal findings of these trials, with discussion of their strengths, limitations, and applicability to the general population. The results support the hypothesis that in patients with SIHD, early revascularization with PCI in combination with OMT is not superior to OMT alone in reducing mortality and other major cardiovascular events. Subset analysis from BARI-2D did suggest that early CABG, although it did not reduce mortality, significantly reduced the rate of nonfatal myocardial infarction compared with an initial OMT approach. Based on these data, the majority of patients with SIHD should be managed initially with medical therapy, a strategy that is also the most cost effective. Revascularization can be considered for patients with severe or refractory symptoms despite a trial of medical therapy. For diabetic patients who have extensive coronary artery disease, early revascularization with CABG may be reasonable.