Essential cellular regulatory elements of oxidative stress in early and late phases of apoptosis in the central nervous system

Impact of Autoimmune Demyelinating Brain Disease Sera on Pericyte Survival

Introduction

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) characterized by demyelination and brain pericyte dysfunction might be involved in MS pathogenesis Our aim was to evaluate whether the factors in serum affect pericyte survival.

Method

C57BL/6 female mice were immunized with myelin oligodendrocyte glycoprotein (MOG) to induce experimental autoimmune encephalomyelitis (EAE). To confirm the animal model, the sera level of anti-MOG antibody in mice and platelet-derived growth factor-BB (PDGF-BB) in patients was measured by ELISA. Human brain vascular pericytes (HBVP) cell lines were incubated with sera of EAE mice and primer progressive MS (PPMS), seconder progressive MS (SPMS) and relapsing-remitting MS (RRMS) patients. The viability of HBVP is measured with Annexin V-FITC/propidium iodide staining with flow cytometry.

Results

Annexin V-FITC/propidium iodide staining with flow cytometry showed increased ratios of early apoptosis and decreased survival following incubation with sera of EAE and progressive MS. Levels of platelet-derived growth factor-BB were identical in serum and cerebrospinal fluids of patients with different forms of MS.

Conclusion

Our results suggest that serum factors might contribute to progressive MS pathogenesis via pericyte dysfunction.

Seizure-Induced Oxidative Stress in Status Epilepticus: Is Antioxidant Beneficial?

Epilepsy is a common neurological disorder which affects patients physically and mentally and causes a real burden for the patient, family and society both medically and economically. Currently, more than one-third of epilepsy patients are still under unsatisfied control, even with new anticonvulsants. Other measures may be added to those with drug-resistant epilepsy. Excessive neuronal synchronization is the hallmark of epileptic activity and prolonged epileptic discharges such as in status epilepticus can lead to various cellular events and result in neuronal damage or death. Unbalanced oxidative status is one of the early cellular events and a critical factor to determine the fate of neurons in epilepsy. To counteract excessive oxidative damage through exogenous antioxidant supplements or induction of endogenous antioxidative capability may be a reasonable approach for current anticonvulsant therapy. In this article, we will introduce the critical roles of oxidative stress and further discuss the potential use of antioxidants in this devastating disease.

Nanoformulated ellagic acid ameliorates pentylenetetrazol-induced experimental epileptic seizures by modulating oxidative stress, inflammatory cytokines and apoptosis in the brains of male mice

The present study evaluated the neuroprotective and antiepileptic efficacy of ellagic acid (EA) encapsulated in calcium-alginate nanoparticles (Ca²⁺-ALG NPs) in pentylenetetrazol (PTZ)-induced seizures in male mice. EA was encapsulated in ALG NPs using a nanospray drying method followed by ionotropic crosslinking with Ca²⁺. Characterization of the developed Ca²⁺-crosslinked EA-ALG NPs showed spherical, high stability NPs; successful loading of EA within crosslinked ALG NPs; and sustained release of EA. Male Swiss albino mice were divided into ten groups as follows; Group I- (control), Group II (50 mg EA /kg) - (EA), Group III polyethylene glycol (PEG), Group IV EA NPs (50 mg/kg) - (EA NP), Group (50 mg/kg alginate) V void V NPs - (void NPs), Group VI: (37.5 PTZ mg/kg) -(PTZ), Group VII: PTZ and EA - (PTZ-EA). Group VIII: animals received PTZ and PEG concurrently (PTZ-PEG). Group IX; animals received PTZ and void NPs concurrently - (PTZ-void). Group X: animals received PTZ and EA NPs concurrently (PTZ-EA NPs). PTZ was used to induce experimental epilepsy. Ca²⁺-ALG NPs prevented seizures throughout the experimental period and had a more prominent effect than free EA did. Ca²⁺-ALG NPs prevented increased glutamate, decreased GABA concentrations and ameliorated increased amyloid-β and homocysteine levels in the serum and brain. Ca²⁺-EA-ALG NPs were superior to free EA in improving increased IL-6 and TNF-α. Ca²⁺-ALG NPs ameliorated PTZ-induced oxidative stress, as evidenced by decreased 4HNE levels and enhanced GSH, GR and GPx levels in the brain. These changes were accompanied by amelioration of apoptosis and its regulating proteins, including Cytochrome C, P53, Bax, Bcl2 and caspase-3 and caspase-9, and protected against DNA damage. Histological examination of the hippocampus confirmed that the neuroprotective effect of Ca²⁺-EA-ALG NPs was superior and more effective than that of free EA.

Platelet Endothelial Cell Adhesion Molecule-1 and Oligodendrogenesis: Significance in Alcohol Use Disorders

Alcoholism is a chronic relapsing disorder with few therapeutic strategies that address the core pathophysiology. Brain tissue loss and oxidative damage are key components of alcoholism, such that reversal of these phenomena may help break the addictive cycle in alcohol use disorder (AUD). The current review focuses on platelet endothelial cell adhesion molecule 1 (PECAM-1), a key modulator of the cerebral endothelial integrity and neuroinflammation, and a targetable transmembrane protein whose interaction within AUD has not been well explored. The current review will elaborate on the function of PECAM-1 in physiology and pathology and infer its contribution in AUD neuropathology. Recent research reveals that oligodendrocytes, whose primary function is myelination of neurons in the brain, are a key component in new learning and adaptation to environmental challenges. The current review briefly introduces the role of oligodendrocytes in healthy physiology and neuropathology. Importantly, we will highlight the recent evidence of dysregulation of oligodendrocytes in the context of AUD and then discuss their potential interaction with PECAM-1 on the cerebral endothelium.

Properties of cells through life and death - an acoustic microscopy investigation

Current methods to evaluate the status of a cell are largely focused on fluorescent identification of molecular biomarkers. The invasive nature of these methods - requiring either fixation, chemical dyes, genetic alteration, or a combination of these - prevents subsequent analysis of samples. In light of this limitation, studies have considered the use of physical markers to differentiate cell stages. Acoustic microscopy is an ultrahigh frequency (>100 MHz) ultrasound technology that can be used to calculate the mechanical and physical properties of biological cells in real-time, thereby evaluating cell stage in live cells without invasive biomarker evaluation. Using acoustic microscopy, MCF-7 human breast adenocarcinoma cells within the G1, G2, and metaphase phases of the proliferative cell cycle, in addition to early and late programmed cell death, were examined. Physical properties calculated include the cell height, sound speed, acoustic impedance, cell density, adiabatic bulk modulus, and the ultrasonic attenuation. A total of 290 cells were measured, 58 from each cell phase, assessed using fluorescent and phase contrast microscopy. Cells actively progressing from G1 to metaphase were marked by a 28% decrease in attenuation, in contrast to the induction of apoptosis from G1, which was marked by a significant 81% increase in attenuation. Furthermore late apoptotic cells separated into 2 distinct groups based on ultrasound attenuation, suggesting that presently-unidentified sub-stages may exist within late apoptosis. A methodology has been implemented for the identification of cell stages without the use of chemical dyes, fixation, or genetic manipulation.

Targeting PRAS40 for multiple diseases

Proline-rich Akt substrate 40kDa (PRAS40) bridges cell signaling between protein kinase B (Akt) and the mammalian target of rapamycin complex 1 (mTORC1). Both Akt and mTORC1 can phosphorylate PRAS40. As a negative regulator of mTORC1, PRAS40 prevents the binding of mTOR to its substrates. The phosphorylation of PRAS40 results in its dissociation from mTORC1 and enhanced mTOR activation. PRAS40 in conjunction with mTORC1 has been closely associated with programmed cell death and is implicated in diabetes mellitus (DM), cardiovascular diseases, cancer, and neurological diseases. Thus, targeting PRAS40 might hold great promise for innovative therapeutic strategies for these diseases.

Neuroprotective effect of hydrogen sulfide on acute cauda equina injury in rats

BACKGROUND

Hydrogen sulfide (H2S), as a novel gaseous messenger molecule, plays an important role in signal transduction and biological modulation.

PURPOSE

In the present study the effect of H2S after compression injury of cauda equina was studied.

STUDY DESIGN

The setting of this study is the laboratory investigation.

METHODS

A total of 162 rats were randomly allocated into three groups: sham group, compression group, and H2S group. Cauda equina compression (CEC) injury in rats was induced by implanting silicone gels (10×1×1 mm) into the epidural spaces L5 and L6; laminectomy was performed at the L4 level of the vertebra in the sham-operated group. The experimental group was treated with sodium hydrosulfide intraperitoneally (20 µmol/kg body weight), whereas the compression and sham groups received equal volumes of physiological saline. Levels of malonaldehyde (MDA) and glutathione (GSH) were determined immediately before CEC surgery, 12 h, 24 h, 48 h, and 72 h after CEC surgery. Furthermore, hematoxylin and eosin (H&E) staining and terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick-end labeling (TUNEL) assay were performed 48 h after CEC.

RESULTS

Hematoxylin and eosin staining showed that myelin sheath and the cauda equina fibers in the compression group were less compact and highly degenerated compared with the sham group, and that H2S treatment could improve the status. Terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick-end labeling staining exhibited that decreased number of TUNEL positive cells was found in the H2S group than in the compression group. The level of MDA was increased in the sham and H2S groups compared with the compression group (p<.05, p<.01), whereas the level of GSH was decreased (p<.05, p<.01).

CONCLUSIONS

With the above data, we conclude that H2S could reduce the oxidative stress and has neuroprotective effect in acute cauda equina syndrome.

Activated microglia cause reversible apoptosis of pheochromocytoma cells, inducing their cell death by phagocytosis

Some apoptotic processes, such as phosphatidylserine exposure, are potentially reversible and do not necessarily lead to cell death. However, phosphatidylserine exposure can induce phagocytosis of a cell, resulting in cell death by phagocytosis: phagoptosis. Phagoptosis of neurons by microglia might contribute to neuropathology, whereas phagoptosis of tumour cells by macrophages might limit cancer. Here, we examined the mechanisms by which BV-2 microglia killed co-cultured pheochromocytoma (PC12) cells that were either undifferentiated or differentiated into neuronal cells. We found that microglia activated by lipopolysaccharide rapidly phagocytosed PC12 cells. Activated microglia caused reversible phosphatidylserine exposure on and reversible caspase activation in PC12 cells, and caspase inhibition prevented phosphatidylserine exposur and decreased subsequent phagocytosis. Nitric oxide was necessary and sufficient to induce the reversible phosphatidylserine exposure and phagocytosis. The PC12 cells were not dead at the time they were phagocytised, and inhibition of their phagocytosis left viable cells. Cell loss was inhibited by blocking phagocytosis mediated by phosphatidylserine, MFG-E8, vitronectin receptors or P2Y6 receptors. Thus, activated microglia can induce reversible apoptosis of target cells, which is insufficient to cause apoptotic cell death, but sufficient to induce their phagocytosis and therefore cell death by phagoptosis.

The effect of regular exercise on antioxidant enzyme activities and lipid peroxidation levels in both hippocampi after occluding one carotid in rat

Regular exercise has beneficial effects on cerebrovascular diseases; however, its biochemical mechanisms are not fully known. The purpose of this study was to determine antioxidant enzyme activities and lipid peroxidation of both hippocampi after applying exercise followed by occluding one common carotid. Wistar rats were divided into four groups of control, exercise, hypoperfusion and exercise-hypoperfusion (exe-hypo). In the exercise and exe-hypo groups, the rats were forced to run on a treadmill for 1 h a day for 2 months. The right common carotid of the animals in the (exe-hypo) group was occluded after the cessation of exercise. Surgery without occlusion of the carotid was applied on the control (without exercise) and exercise groups. All animals were sacrificed 1 and 24 h after surgery. The levels of malondialdehyde (MDA) and antioxidant enzyme activities in the hippocampi were measured. A significant interaction was observed between the exercise and hypoperfusion in both hippocampi (p<0.05). In comparison with the control group, there was significant elevation of catalase activity in the right and left hippocampus of the hypo group at 24 h (p<0.0001). Regarding the differences between the hemispheres, there was a significant increase in MDA and decrease in catalase activity in the left hippocampus in hypoperfusion group, but the exercise in the exe-hypo group succeeded in abolishing these alterations which were caused by hypoperfusion, This study shows that exercise pre-conditioning prevents some alterations in brain oxidant-antioxidant status which are induced by cerebral hypoperfusion. Further studies are needed in order to clarify the mechanism of exercise.

The regulatory T cell effector soluble fibrinogen-like protein 2 induces tubular epithelial cell apoptosis in renal transplantation

Acute rejection (AR) hinders renal allograft survival. Tubular epithelial cell (TEC) apoptosis contributes to premature graft loss in AR, while the mechanism remains unclear. Soluble fibrinogen-like protein 2 (sFGL2), a novel effector of regulatory T cells (Treg), induces apoptosis to mediate tissue injury. We previously found that serum sFGL2 significantly increased in renal allograft rejection patients. In this study, the role of sFGL2 in AR was further investigated both in vivo and in vitro. The serum level of sFGL2 and the percentage of CD4(+)CD25(+)Foxp3(+) Treg in the peripheral blood were measured in renal allograft recipients with AR or stable renal function (n = 30 per group). The human TEC was stimulated with sFGL2, tumor necrosis factor (TNF)-α, or phosphate buffered saline and investigated for apoptosis in vitro. Apoptosis-associated genes expression in TEC was further assessed. Approval for this study was obtained from the Ethics Committee of Fudan University. Our results showed that the serum level of sFGL2, correlated with Treg in the peripheral blood, was significantly increased in the AR patients. In vitro, sFGL2 remarkably induced TEC apoptosis, with a significant up-regulation of proapoptotic genes, including CASP-3, CASP-8, CASP-9, CASP-10, TRADD, TNFSF10, FADD, FAS, FASLG, BAK1, BAD, BAX, and NF-KB1. However, no significant changes were observed in the expression of antiapoptotic genes, including CARD-18, NAIP, BCL2, IKBKB, and TBK1. Therefore, sFGL2, an effector of Treg, induces TEC apoptosis. Our study suggests that sFGL2 is a potential mediator in the pathogenesis of allograft rejection and provides novel insights into the role of Treg in AR.

Zinc promotes the death of hypoxic astrocytes by upregulating hypoxia-induced hypoxia-inducible factor-1alpha expression via poly(ADP-ribose) polymerase-1

AIM

Pathological release of excess zinc ions has been implicated in ischemic brain cell death. However, the underlying mechanisms remain to be elucidated. In stroke, ischemia-induced zinc release and hypoxia-inducible factor-1 (HIF-1) accumulation concurrently occur in the ischemic tissue. The present study tests the hypothesis that the presence of high intracellular zinc concentration is a major cause of modifications to PARP-1 and HIF-1α during hypoxia, which significantly contributes to cell death during ischemia.

METHODS

Primary cortical astrocytes and C8-D1A cells were exposed to different concentrations of zinc chloride. Cell death rate and protein expression of HIF-1 and Poly(ADP-ribose) polymerase (PARP)-1 were examined after 3-h hypoxic treatment.

RESULTS

Although 3-h hypoxia or 100 μM of zinc alone did not induce noticeable cytotoxicity, their combination led to a dramatic increase in astrocytic cell death in a zinc-concentration-dependent manner. Exposure of astrocytes to hypoxia for 3 h remarkably increased the levels of intracellular zinc and HIF-1α protein, which was further augmented by added exogenous zinc. Notably, HIF-1α knockdown blocked zinc-induced astrocyte death. Moreover, knockdown of PARP-1, another important protein in the response of hypoxia, attenuated the overexpression of HIF-1α and reduced the cell death rate.

CONCLUSIONS

Our studies show that zinc promotes hypoxic cell death through overexpression of the hypoxia response factor HIF-1α via the cell fate determine factor PARP-1 modification, which provides a novel mechanism for zinc-mediated ischemic brain injury.

Experimental studies of erythropoietin protection following traumatic brain injury in rats

This study aimed to explore the effect of erythropoietin (EPO) on brain tissue after traumatic brain injury in rats. Animals were divided into sham, control and EPO groups. The model was constructed using the improved Feeney’s free falling weight traumatic brain injury model. The brain water content and the number of the apoptotic monocyte chemotactic protein-1⁺ (MCP-1⁺) and CD68⁺ cells were monitored at 12, 48 and 120 h post-trauma. The water content was lower in the EPO group at each time point compared to the control group. The number of apoptotic MCP-1⁺ and CD68⁺ cells surrounding the traumatic brain injury lesion was less in the EPO group compared to these values in the control group. In conclusion, following traumatic brain injury, EPO significantly decreased the number of apoptotic cells, the expression of MCP-1, the infiltration of CD68⁺ cells as well as brain edema to protect the brain.

Beneficial effects of sulindac in focal cerebral ischemia: a positive role in Wnt/β-catenin pathway

BACKGROUND

Accumulated evidences have established that inflammatory damage plays an important role in cerebral ischemic pathogenesis and may represent a target for treatment. Sulindac is well known as a nonsteroidal anti-inflammatory drug. However, little is known regarding the effect of sulindac in acute cerebral ischemia. Here, we designed this study to investigate the potential protective effects of sulindac in focal cerebral ischemia and the mechanisms underlying in vivo.

METHODS

Focal cerebral ischemia was induced in male Sprague-Dawley rats by permanent middle cerebral artery occlusion (pMCAO). Sulindac was administrated at dose of 4, 10, or 20mg/kg at 30 min before the operation. Neurological deficit scores, brain water content and infarct volumes were measured at 24h after pMCAO. Immunohistochemistry, western blot and reverse transcription-polymerase chain reaction were used for examining the mediators involved in Wnt/β-catenin signaling pathway, including the positive regulators dishevelled (Dvl) and β-catenin, the negative regulators adenomatous polyposis coli (APC), and P-β-catenin, as well as the downstream targets Bcl-2, Bax and claudin-5.

RESULTS

Compared with Vehicle group, 20mg/kg sulindac reduced neurological deficits, brain water content and infarct volumes. The same dose of sulindac upregulated the expression of Dvl, β-catenin, Bcl2 and claudin-5, and downregulated APC, P-β-catenin and Bax compared with Vehicle group.

CONCLUSIONS

These results showed that sulindac had a significant beneficial effect in cerebral ischemia; this effect may be correlated with the activation of the Wnt/β-catenin signaling.

Novel avenues of drug discovery and biomarkers for diabetes mellitus

Globally, developed nations spend a significant amount of their resources on health care initiatives that poorly translate into increased population life expectancy. As an example, the United States devotes 16% of its gross domestic product to health care, the highest level in the world, but falls behind other nations that enjoy greater individual life expectancy. These observations point to the need for pioneering avenues of drug discovery to increase life span with controlled costs. In particular, innovative drug development for metabolic disorders such as diabetes mellitus becomes increasingly critical given that the number of diabetic people will increase exponentially over the next 20 years. This article discusses the elucidation and targeting of novel cellular pathways that are intimately tied to oxidative stress in diabetes mellitus for new treatment strategies. Pathways that involve wingless, β-nicotinamide adenine dinucleotide (NAD(+)) precursors, and cytokines govern complex biological pathways that determine both cell survival and longevity during diabetes mellitus and its complications. Furthermore, the role of these entities as biomarkers for disease can further enhance their utility irrespective of their treatment potential. Greater understanding of the intricacies of these unique cellular mechanisms will shape future drug discovery for diabetes mellitus to provide focused clinical care with limited or absent long-term complications.

Therapeutic promise and principles: metabotropic glutamate receptors

For a number of disease entities, oxidative stress becomes a significant factor in the etiology and progression of cell dysfunction and injury. Therapeutic strategies that can identify novel signal transduction pathways to ameliorate the toxic effects of oxidative stress may lead to new avenues of treatment for a spectrum of disorders that include diabetes, Alzheimer's disease, Parkinson's disease and immune system dysfunction. In this respect, metabotropic glutamate receptors (mGluRs) may offer exciting prospects for several disorders since these receptors can limit or prevent apoptotic cell injury as well as impact upon cellular development and function. Yet the role of mGluRs is complex in nature and may require specific mGluR modulation for a particular disease entity to maximize clinical efficacy and limit potential disability. Here we discuss the potential clinical translation of mGluRs and highlight the role of novel signal transduction pathways in the metabotropic glutamate system that may be vital for the clinical utility of mGluRs.

A fork in the path: Developing therapeutic inroads with FoxO proteins

Advances in clinical care for disorders involving any system of the body necessitates novel therapeutic strategies that can focus upon the modulation of cellular proliferation, metabolism, inflammation and longevity. In this respect, members of the mammalian forkhead transcription factors of the O class (FoxOs) that include FoxO1, FoxO3, FoxO4 and FoxO6 are increasingly being recognized as exciting prospects for multiple disorders. These transcription factors govern development, proliferation, survival and longevity during multiple cellular environments that can involve oxidative stress. Furthermore, these transcription factors are closely integrated with several novel signal transduction pathways, such as erythropoietin and Wnt proteins, that may influence the ability of FoxOs to act as a “double-edge sword” to sometimes promote cell survival, but at other times lead to cell injury. Here we discuss the fascinating but complex role of FoxOs during cellular injury and oxidative stress, progenitor cell development, fertility, angiogenesis, cardiovascular function, cellular metabolism and diabetes, cell longevity, immune surveillance and cancer.

Underlying mechanism for suppression of vascular smooth muscle cells by green tea polyphenol EGCG released from biodegradable polymers for stent application

Epigallocatechin-3-O-gallate (EGCG), the predominant catechin from tea, is known to exert a variety of cardiovascular beneficial effects by affecting the activity of receptor and signal transduction kinases. In this study, we investigated the suppressive effects of EGCG released from biodegradable poly(L-lactide-co-ε-caprolactone, PLCL) films on the proliferation, cell cycle progression and matrix metalloproteinase-2 (MMP-2) expression of vascular smooth muscle cells (VSMCs). The involvement of phosphorylated Akt (pAkt) and nuclear factor-κB (pNF-κB) as well as the internalization of EGCG into VSMCs was also examined as underlying mechanisms for EGCG-mediated VSMC inhibition. The proliferation of canine aortic SMCs (CASMCs) on EGCG-releasing PLCL (E-PLCL) was significantly inhibited. The culture of CASMCs on E-PLCL resulted in induction of cell cycle arrest at G(0)/G(1) phase and inactivation of pAkt, leading to subsequent apoptosis. Active MMP-2 expression was directly lowered by EGCG released from E-PLCL and indirectly inhibited by the EGCG-mediated suppression of pNF-κB. We also observed the incorporation of fluorescein isothiocyanate-conjugated EGCG into the cytoplasm of CASMCs and its further nuclear translocation, which could lead to the interruption of the exogenous signals directed to genes responsible for cellular responses of CASMCs. Taken together, the attenuated responses of VSMCs to E-PLCL were shown to be mediated through the suppression of pNF-κB, pAkt and each subsequent target genes or proteins by EGCG incorporated into the cells.

Mammalian target of rapamycin: hitting the bull's-eye for neurological disorders

The mammalian target of rapamycin (mTOR) and its associated cell signaling pathways have garnered significant attention for their roles in cell biology and oncology. Interestingly,the explosion of information in this field has linked mTOR to neurological diseases with promising initial studies. mTOR, a 289 kDa serine/threonine protein kinase, plays an important role in cell growth and proliferation and is activated through phosphorylation in response to growth factors, mitogens and hormones. Growth factors, amino acids, cellular nutrients and oxygen deficiency can downregulate mTOR activity. The function of mTOR signaling is mediated primarily through two mTOR complexes: mTORC1 and mTORC2. mTORC1 initiates cap-dependent protein translation, a rate-limiting step of protein synthesis, through the phosphorylation of the targets eukaryotic initiation factor 4E-binding protein 1 (4EBP1) and p70 ribosomal S6 kinase (p70S6K). In contrast, mTORC2 regulates development of the cytoskeleton and also controls cell survival. Although closely tied to tumorigenesis, mTOR and the downstream signaling pathways are significantly involved in the central nervous system (CNS) with synaptic plasticity, memory retention, neuroendocrine regulation associated with food intake and puberty and modulation of neuronal repair following injury. The signaling pathways of mTOR also are believed to be a significant component in a number of neurological diseases, such as Alzheimer disease, Parkinson disease and Huntington disease, tuberous sclerosis, neurofibromatosis, fragile X syndrome, epilepsy, traumatic brain injury and ischemic stroke. Here we describe the role of mTOR in the CNS and illustrate the potential for new strategies directed against neurological disorders.

Roles of zinc and metallothionein-3 in oxidative stress-induced lysosomal dysfunction, cell death, and autophagy in neurons and astrocytes

Zinc dyshomeostasis has been recognized as an important mechanism for cell death in acute brain injury. An increase in the level of free or histochemically reactive zinc in astrocytes and neurons is considered one of the major causes of death of these cells in ischemia and trauma. Although zinc dyshomeostasis can lead to cell death via diverse routes, the major pathway appears to involve oxidative stress.

Recently, we found that a rise of zinc in autophagic vacuoles, including autolysosomes, is a prerequisite for lysosomal membrane permeabilization and cell death in cultured brain cells exposed to oxidative stress conditions. The source of zinc in this process is likely redox-sensitive zinc-binding proteins such as metallothioneins, which release zinc under oxidative conditions. Of the metallothioneins, metallothionein-3 is especially enriched in the central nervous system, but its physiologic role in this tissue is not well established. Like other metallothioneins, metallothionein-3 may function as metal detoxicant, but is also known to inhibit neurite outgrowth and, sometimes, promote neuronal death, likely by serving as a source of toxic zinc release. In addition, metallothionein-3 regulates lysosomal functions. In the absence of metallothionein-3, there are changes in lysosome-associated membrane protein-1 and -2, and reductions in certain lysosomal enzymes that result in decreased autophagic flux. This may have dual effects on cell survival. In acute oxidative injury, zinc dyshomeostasis and lysosomal membrane permeabilization are diminished in metallothionein-3 null cells, resulting in less cell death. But over the longer term, diminished lysosomal function may lead to the accumulation of abnormal proteins and cause cytotoxicity.

The roles of zinc and metallothionein-3 in autophagy and/or lysosomal function have just begun to be investigated. In light of evidence that autophagy and lysosomes may play significant roles in the pathogenesis of various neurological diseases, further insight into the contribution of zinc dynamics and metallothionein-3 function may help provide ways to effectively regulate these processes in brain cells.

Activation of bone remodeling after fatigue: differential response to linear microcracks and diffuse damage

Recent experiments point to two predominant forms of fatigue microdamage in bone: linear microcracks (tens to a few hundred microns in length) and "diffuse damage" (patches of diffuse stain uptake in fatigued bone comprised of clusters of sublamellar-sized cracks). The physiological relevance of diffuse damage in activating bone remodeling is not known. In this study microdamage amount and type were varied to assess whether linear or diffuse microdamage has similar effects on the activation of intracortical resorption. Activation of resorption was correlated to the number of linear microcracks (Cr.Dn) in the bone (R(2)=0.60, p<0.01). In contrast, there was no activation of resorption in response to diffuse microdamage alone. Furthermore, there was no significant change in osteocyte viability in response to diffuse microdamage, suggesting that osteocyte apoptosis, which is known to activate remodeling at typical linear microcracks in bone, does not result from sublamellar damage. These findings indicate that inability of diffuse microdamage to activate resorption may be due to lack of a focal injury response. Finally, we found that duration of loading does not affect the remodeling response. In conclusion, our data indicate that osteocytes activate resorption in response to linear microcracks but not diffuse microdamage, perhaps due to lack of a focal injury-induced apoptotic response.

Diabetes mellitus: channeling care through cellular discovery

Diabetes mellitus (DM) impacts a significant portion of the world's population and care for this disorder places an economic burden on the gross domestic product for any particular country. Furthermore, both Type 1 and Type 2 DM are becoming increasingly prevalent and there is increased incidence of impaired glucose tolerance in the young. The complications of DM are protean and can involve multiple systems throughout the body that are susceptible to the detrimental effects of oxidative stress and apoptotic cell injury. For these reasons, innovative strategies are necessary for the implementation of new treatments for DM that are generated through the further understanding of cellular pathways that govern the pathological consequences of DM. In particular, both the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD(+)), nicotinamide, and the growth factor erythropoietin offer novel platforms for drug discovery that involve cellular metabolic homeostasis and inflammatory cell control. Interestingly, these agents and their tightly associated pathways that consist of cell cycle regulation, protein kinase B, forkhead transcription factors, and Wnt signaling also function in a broader sense as biomarkers for disease onset and progression.

Effect of osmotic shock and urea on phosphatidylserine scrambling in thrombocyte cell membranes

Blood passing the renal medulla enters a strongly hypertonic environment challenging functional properties and survival of blood cells. In erythrocytes, exposure to hyperosmotic shock stimulates Ca(2+) entry and ceramide formation with subsequent cell membrane scrambling, an effect partially reversed by high concentrations of Cl(-) or urea. Cell membrane scrambling with phosphatidylserine exposure is part of the procoagulant phenotype of platelets. Coagulation in the hypertonic renal medulla would jeopardize blood flow in the vasa recta. The present study thus explored whether hypertonic environment and urea modify phosphatidylserine exposure of human platelets. FACS analysis was employed to estimate cytosolic Ca(2+) activity with Fluo3 fluorescence, ceramide formation, P-selectin, and glycoprotein IIb/IIIa activation with fluorescent antibodies and phosphatidylserine exposure with annexin V-binding. The spontaneous platelet aggregation was measured by impedance aggregometry. Hyperosmotic shock (addition of 500 mM sucrose or 250 mM NaCl) significantly enhanced cytosolic Ca(2+) activity, ceramide formation, phosphatidylserine exposure, platelet degranulation, and aggregability. Addition of 500 mM urea to isotonic saline did not significantly modify cytosolic Ca(2+) activity, ceramide abundance, or annexin V-binding but significantly blunted the respective effects of hypertonic shock following addition of 500 mM sucrose. In isotonic solutions, both ceramide (20 microM) and Ca(2+) ionophore ionomycin (0.5 microM) increased annexin V-binding, effects again significantly blunted by 500 mM urea. Moreover, oxidative stress by addition of 0.5 mM peroxynitrite increased cytosolic Ca(2+) activity and triggered annexin V-binding, effects again blunted in the presence of 500 mM urea. The observations reveal that hyperosmotic shock and oxidative stress trigger a procoagulant platelet phenotype, an effect blunted by the presence of high urea concentrations.

Heat acclimation provides sustained improvement in functional recovery and attenuates apoptosis after traumatic brain injury

Heat acclimation (HA) offers functional neuroprotection in mice after traumatic brain injury (TBI). This study further characterizes endogenous neuroprotection acquired by HA (34+/-1 degrees C, 30 d) after TBI. We establish here the ability of HA to induce sustained functional benefits and to reduce activation of apoptotic pathways. Neurobehavioral recovery, assessed by the Neurological Severity Score, was greater in HA mice up to 8 days after injury as compared with normothermic controls (P<0.05) and lesion volume was also smaller in the HA group (P<0.05). Reduced apoptotic cell death in HA mice was confirmed using caspase-3 activity measurements and immunohistochemistry. To investigate the underlying molecular pathways, expression levels of intrinsic apoptotic pathway-related proteins were examined. HA mice displayed higher mitochondrial levels of antiapoptotic Bcl-xL, accompanied by lower proapoptotic Bad levels and decreased cytochrome c release, suggesting a higher apoptotic threshold. Taken together with our previous reports, indicating increased Akt phosphorylation and antioxidative capacity, alongside with reduced tumor necrosis alpha levels after TBI in HA animals, the current results support the involvement of an antiapoptotic effect in HA-induced neuroprotection. Current results warrant further study as TBI-induced apoptosis may persist over weeks after injury, possibly providing a target for belated therapeutic intervention.

Oxidative stress: Biomarkers and novel therapeutic pathways

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO) and members of the mammalian forkhead transcription factors of the O class (FoxOs) may offer the greatest promise for new treatment regimens since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. However, biological outcome with EPO and FoxOs may sometimes be both unexpected and undesirable that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as complicated role EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.

Oxidative injury triggers autophagy in astrocytes: the role of endogenous zinc

We have recently demonstrated that the accumulation of labile zinc in lysosomes during oxidative stress causes lysosomal membrane permeabilization (LMP) in cultured hippocampal neurons. Since autophagy involves fusion of autophagic vacuoles (AVs) with lysosomes, zinc accumulation may start in AVs. In the present study, we examined the role of endogenous zinc in H2O2-induced autophagy and cell death in mouse astrocyte cultures. Live-cell confocal imaging of astrocytes transfected with GFP-LC3 revealed that the number of AVs positive for LC3 (microtubule-associated protein 1 light chain 3) increased following exposure to H2O2 or ferrous chloride (FeCl2). Staining of RFP-LC3-transfected astrocytes with FluoZin-3 indicated that the levels of labile zinc increased in AVs as well as in the cytosol and nuclei. The majority of AVs were double-stained with LysoTracker, indicating that they were fused with lysosomes. Chelation of zinc with tetrakis [2-pyridylmethyl]ethylenediamine (TPEN) decreased the number of AVs in H2O2-treated astrocytes, whereas exposure to zinc increased their number, suggesting that dysregulation of zinc homeostasis is mechanistically linked to autophagy. Unexpectedly, inhibition of autophagy blocked the rise in labile zinc levels. Astrocytic death induced by H2O2) was ccompanied by LMP. Autophagy inhibitors (3-methyladenine, bafilomycin-1) or TPEN attenuated LMP and cell death in astrocytes. These results support the possibility that endogenous zinc plays a key role in autophagy under oxidative stress in astrocytes, and suggest that autophagy is a necessary preceding event for LMP and cell death in oxidative injury.

New strategies for Alzheimer's disease and cognitive impairment

Approximately five million people suffer with Alzheimer's disease (AD) and more than twenty-four million people are diagnosed with AD, pre-senile dementia, and other disorders of cognitive loss worldwide. Furthermore, the annual cost per patient with AD can approach $200,000 with an annual population aggregate cost of $100 billion. Yet, complete therapeutic prevention or reversal of neurovascular injury during AD and cognitive loss is not achievable despite the current understanding of the cellular pathways that modulate nervous system injury during these disorders. As a result, identification of novel therapeutic targets for the treatment of neurovascular injury would be extremely beneficial to reduce or eliminate disability from diseases that lead to cognitive loss or impairment. Here we describe the capacity of intrinsic cellular mechanisms for the novel pathways of erythropoietin and forkhead transcription factors that may offer not only new strategies for disorders such as AD and cognitive loss, but also function as biomarkers for disease onset and progression.

Erythropoietin, forkhead proteins, and oxidative injury: biomarkers and biology

Oxidative stress significantly impacts multiple cellular pathways that can lead to the initiation and progression of varied disorders throughout the body. It therefore becomes imperative to elucidate the components and function of novel therapeutic strategies against oxidative stress to further clinical diagnosis and care. In particular, both the growth factor and cytokine erythropoietin (EPO), and members of the mammalian forkhead transcription factors of the O class (FoxOs), may offer the greatest promise for new treatment regimens, since these agents and the cellular pathways they oversee cover a range of critical functions that directly influence progenitor cell development, cell survival and degeneration, metabolism, immune function, and cancer cell invasion. Furthermore, both EPO and FoxOs function not only as therapeutic targets, but also as biomarkers of disease onset and progression, since their cellular pathways are closely linked and overlap with several unique signal transduction pathways. Yet, EPO and FoxOs may sometimes have unexpected and undesirable effects that can raise caution for these agents and warrant further investigations. Here we present the exciting as well as the complex role that EPO and FoxOs possess to uncover the benefits as well as the risks of these agents for cell biology and clinical care in processes that range from stem cell development to uncontrolled cellular proliferation.

The vitamin nicotinamide: translating nutrition into clinical care

Nicotinamide, the amide form of vitamin B(3) (niacin), is changed to its mononucleotide compound with the enzyme nicotinic acide/nicotinamide adenylyltransferase, and participates in the cellular energy metabolism that directly impacts normal physiology. However, nicotinamide also influences oxidative stress and modulates multiple pathways tied to both cellular survival and death. During disorders that include immune system dysfunction, diabetes, and aging-related diseases, nicotinamide is a robust cytoprotectant that blocks cellular inflammatory cell activation, early apoptotic phosphatidylserine exposure, and late nuclear DNA degradation. Nicotinamide relies upon unique cellular pathways that involve forkhead transcription factors, sirtuins, protein kinase B (Akt), Bad, caspases, and poly (ADP-ribose) polymerase that may offer a fine line with determining cellular longevity, cell survival, and unwanted cancer progression. If one is cognizant of the these considerations, it becomes evident that nicotinamide holds great potential for multiple disease entities, but the development of new therapeutic strategies rests heavily upon the elucidation of the novel cellular pathways that nicotinamide closely governs.

Vitamin K prevents oxidative cell death by inhibiting activation of 12-lipoxygenase in developing oligodendrocytes

Oxidative mechanisms of injury are important in many neurological disorders. Developing oligodendrocytes (pre-OLs) are particularly sensitive to oxidative stress-mediated injury. We previously demonstrated a novel function of phylloquinone (vitamin K(1)) and menaquinone 4 (MK-4; a major form of vitamin K2) in protecting pre-OLs and immature neurons against glutathione depletion-induced oxidative damage (Li et al. [ 2003] J. Neurosci. 23:5816-5826). Here we report that vitamin K at nanomolar concentrations prevents arachidonic acid-induced oxidative injury to pre-OLs through blocking the activation of 12-lipoxygenase (12-LOX). Arachidonic acid metabolism is a potential source for reactive oxygen species (ROS) generation during ischemia and reperfusion. Exposure of pre-OLs to arachidonic acid resulted in oxidative cell death in a concentration-dependent manner. Administration of vitamin K (K(1) and MK-4) completely prevented the toxicity. Consistent with our previous findings, inhibitors of 12-LOX abolished ROS production and cell death, indicating that activation of 12-LOX is a key event in arachidonic acid-induced pre-OL death. Vitamin K(1) and MK-4 significantly blocked 12-LOX activation and prevented ROS accumulation in pre-OLs challenged with arachidonic acid. However, vitamin K itself did not directly inhibit 12-LOX enzymatic activity when assayed with purified 12-LOX in vitro. These results suggest that vitamin K, or likely its metabolites, acts upstream of activation of 12-LOX in pre-OLs. In summary, our data indicate that vitamin K prevents oxidative cell death by blocking activation of 12-LOX and ROS generation.

A "FOXO" in sight: targeting Foxo proteins from conception to cancer

The successful treatment for multiple disease entities can rest heavily upon the ability to elucidate the intricate relationships that govern cellular proliferation, metabolism, survival, and inflammation. Here we discuss the therapeutic potential of the mammalian forkhead transcription factors predominantly in the O class, FoxO1, FoxO3, FoxO4, and FoxO6, which play a significant role during normal cellular function as well as during progressive disease. These transcription factors are integrated with several signal transduction pathways, such as Wnt proteins, that can regulate a broad array of cellular process that include stem cell proliferation, aging, and malignancy. FoxO transcription factors are attractive considerations for strategies directed against human cancer in light of their pro-apoptotic effects and ability to lead to cell cycle arrest. Yet, FoxO proteins can be associated with infertility, cellular degeneration, and unchecked cellular proliferation. As our knowledge continues to develop for this novel family of proteins, potential clinical applications for the FoxO family should heighten our ability to limit disease progression without clinical compromise.

The forkhead transcription factor FOXO3a controls microglial inflammatory activation and eventual apoptotic injury through caspase 3

Memory loss and cognitive failure are increasingly being identified as potential risks with the recognized increase in life expectancy of the general population. As a result, the development of novel therapeutic strategies for disorders such as Alzheimer's disease have garnered increased attention. The etiologies that can lead to Alzheimer's disease are extremely varied, but a number of therapeutic options are directed against amyloid-beta peptide and inflammatory cell regulation to prevent or halt progressive cognitive loss. In particular, inflammatory microglial cells may have disparate functions that in some scenarios lead to disability through the removal of functional neurovascular cells and in other circumstances foster tissue repair. Given the significance microglial cells hold for neurodegenerative disorders, we therefore examined the function that amyloid (Abeta(1-42)) has upon the microglial cell line EOC 2 and identified a novel role for the forkhead transcription factor FoxO3a and caspase 3. Here we show that Abeta(1-42) leads to progressive injury and apoptotic cell loss in microglial cells that involves both early phosphatidylserine (PS) externalization and late genomic DNA fragmentation over a 24 hour course. Prior to these injury programs, Abeta(1-42) results in the activation and proliferation of microglia as demonstrated by increased proliferating cell nuclear antigen (PCNA) expression and bromodeoxyuridine (BrdU) uptake. Both apoptotic injury as well as the prior activation and proliferation of microglial cells relies upon the presence of FoxO3a, since specific gene silencing of FoxO3a promotes microglial cell protection and prevents the early activation and proliferation of these cells. Furthermore, Abeta(1-42) exposure maintained FoxO3a in an unphosphorylated "active" state and facilitated the cellular trafficking of FoxO3a from the cytoplasm to the cell nucleus to potentially lead to "pro-apoptotic" programs by this transcription factor. One apoptotic program in particular appears to involve the activation of caspase 3, since loss of FoxO3a through gene silencing prevents the induction of caspase 3 activity by Abeta(1-42).

Alternative medicine and Alzheimer disease

BACKGROUND

Complimentary and alternative medicine has an extensive worldwide history and is commonly used by older patients. A number of different alternative medicines are used by patients having Alzheimer disease. It is both desirable and expected for clinicians to be acquainted with these medications.

REVIEW SUMMARY

This paper discusses the available clinical trial evidence regarding 8 agents commonly used by people having Alzheimer disease. We provide an overview of the history and basic scientific evidence available for each agent, followed by a critical analysis of the evidence available from clinical trials, including the number of participants, trial duration, and specific outcomes evaluated.

CONCLUSION

Although many of these compounds have been associated with interesting basic science, none has shown clear clinical benefit to date. Data available for some, such as Ginkgo biloba, curcumin, and huperzine A, suggest that further evaluation is warranted. Familiarity with this literature will allow clinicians to provide meaningful recommendations to patients who wish to use these agents.

Osteocyte apoptosis controls activation of intracortical resorption in response to bone fatigue

Osteocyte apoptosis is spatially and temporally linked to bone fatigue-induced microdamage and to subsequent intracortical remodeling. Specifically, osteocytes surrounding fatigue microcracks in bone undergo apoptosis, and those regions containing apoptotic osteocytes co-localize exactly with areas subsequently resorbed by osteoclasts. Here we tested the hypothesis that osteocyte apoptosis is a key controlling step in the activation and/or targeting of osteoclastic resorption after bone fatigue. We carried out in vivo fatigue loading of ulna from 4- to 5-mo-old Sprague-Dawley rats treated with an apoptosis inhibitor (the pan-caspase inhibitor Q-VD-OPh) or with vehicle. Intracortical bone remodeling and osteocyte apoptosis were quantitatively assessed by standard histomorphometric techniques on day 14 after fatigue. Continuous exposure to Q-VD-OPh completely blocked both fatigue-induced apoptosis and the activation of osteoclastic resorption, whereas short-term caspase inhibition during only the first 2 days after fatigue resulted in >50% reductions in both osteocyte apoptosis and bone resorption. These results (1) show that osteocyte apoptosis is necessary to initiate intracortical bone remodeling in response to fatigue microdamage, (2) indicate a possible dose-response relationship between the two processes, and (3) suggest that early apoptotic events after fatigue-induced microdamage may play a substantial role in determining the subsequent course of tissue remodeling.

FoxO proteins: cunning concepts and considerations for the cardiovascular system

Dysfunction in the cardiovascular system can lead to the progression of a number of disease entities that can involve cancer, diabetes, cardiac ischaemia, neurodegeneration and immune system dysfunction. In order for new therapeutic avenues to overcome some of the limitations of present clinical treatments for these disorders, future investigations must focus upon novel cellular processes that control cellular development, proliferation, metabolism and inflammation. In this respect, members of the mammalian forkhead transcription factors of the O class (FoxOs) have increasingly become recognized as important and exciting targets for disorders of the cardiovascular system. In the present review, we describe the role of these transcription factors in the cardiovascular system during processes that involve angiogenesis, cardiovascular development, hypertension, cellular metabolism, oxidative stress, stem cell proliferation, immune system regulation and cancer. Current knowledge of FoxO protein function combined with future studies should continue to lay the foundation for the successful translation of these transcription factors into novel and robust clinical therapies.

The "O" class: crafting clinical care with FoxO transcription factors

Forkhead Transcription Factors: Vital Elements in Biology and Medicine provides a unique platform for the presentation of novel work and new insights into the vital role that forkhead transcription factors play in both cellular physiology as well as clinical medicine. Internationally recognized investigators provide their insights and perspectives for a number of forkhead genes and proteins that may have the greatest impact for the development of new strategies for a broad array of disorders that can involve aging, cancer, cardiac function, neurovascular integrity, fertility, stem cell differentiation, cellular metabolism, and immune system regulation. Yet, the work clearly sets a precedent for the necessity to understand the cellular and molecular function of forkhead proteins since this family of transcription factors can limit as well as foster disease progression depending upon the cellular environment. With this in mind, our concluding chapter for Forkhead Transcription Factors: Vital Elements in Biology andMedicine offers to highlight both the diversity and complexity of the forkhead transcription family by focusing upon the mammalian forkhead transcription factors of the O class (FoxOs) that include FoxO1, FoxO3, FoxO4, and FoxO6. FoxO proteins are increasingly considered to represent unique cellular targets that can control numerous processes such as angiogenesis, cardiovascular development, vascular tone, oxidative stress, stem cell proliferation, fertility, and immune surveillance. Furthermore, FoxO transcription factors are exciting considerations for disorders such as cancer in light of their pro-apoptotic and inhibitory cell cycle effects as well as diabetes mellitus given the close association FoxOs hold with cellular metabolism. In addition, these transcription factors are closely integrated with several novel signal transduction pathways, such as erythropoietin and Wnt proteins, that may influence the ability of FoxOs to lead to cell survival or cell injury. Further understanding of both the function and intricate nature of the forkhead transcription factor family, and in particular the FoxO proteins, should allow selective regulation of cellular development or cellular demise for the generation of successful future clinical strategies and patient well-being.

Clever cancer strategies with FoxO transcription factors

Given that cancer and related disorders affect a wide spectrum of the world's population, and in most cases are progressive in nature, it is essential that future care must overcome the present limitations of existing therapies in the absence of toxic side effects. Mammalian forkhead transcription factors of the O class (FoxOs) may fill this niche since these proteins are increasingly considered to represent unique cellular targets directed against human cancer in light of their pro-apoptotic effects and ability to lead to cell cycle arrest. Yet, FoxOs also can significantly affect normal cell survival and longevity, requiring new treatments for neoplastic growth to modulate novel pathways that integrate cell proliferation, metabolism, inflammation and survival. In this respect, members of the FoxO family are extremely compelling to consider since these transcription factors have emerged as versatile proteins that can control angiogenesis, stem cell proliferation, cell adhesion and autoimmune disease. Further elucidation of FoxO protein function during neoplastic growth should continue to lay the foundation for the successful translation of these transcription factors into novel and robust clinical therapies for cancer.

Erythropoietin: elucidating new cellular targets that broaden therapeutic strategies

Given that erythropoietin (EPO) is no longer believed to have exclusive biological activity in the hematopoietic system, EPO is now considered to have applicability in a variety of nervous system disorders that can overlap with vascular disease, metabolic impairments, and immune system function. As a result, EPO may offer efficacy for a broad number of disorders that involve Alzheimer's disease, cardiac insufficiency, stroke, trauma, and diabetic complications. During a number of clinical conditions, EPO is robust and can prevent metabolic compromise, neuronal and vascular degeneration, and inflammatory cell activation. Yet, use of EPO is not without its considerations especially in light of frequent concerns that may compromise clinical care. Recent work has elucidated a number of novel cellular pathways governed by EPO that can open new avenues to avert deleterious effects of this agent and offer previously unrecognized perspectives for therapeutic strategies. Obtaining greater insight into the role of EPO in the nervous system and elucidating its unique cellular pathways may provide greater cellular viability not only in the nervous system but also throughout the body.

Erythropoietin and oxidative stress

Unmitigated oxidative stress can lead to diminished cellular longevity, accelerated aging, and accumulated toxic effects for an organism. Current investigations further suggest the significant disadvantages that can occur with cellular oxidative stress that can lead to clinical disability in a number of disorders, such as myocardial infarction, dementia, stroke, and diabetes. New therapeutic strategies are therefore sought that can be directed toward ameliorating the toxic effects of oxidative stress. Here we discuss the exciting potential of the growth factor and cytokine erythropoietin for the treatment of diseases such as cardiac ischemia, vascular injury, neurodegeneration, and diabetes through the modulation of cellular oxidative stress. Erythropoietin controls a variety of signal transduction pathways during oxidative stress that can involve Janus-tyrosine kinase 2, protein kinase B, signal transducer and activator of transcription pathways, Wnt proteins, mammalian forkhead transcription factors, caspases, and nuclear factor kappaB. Yet, the biological effects of erythropoietin may not always be beneficial and may be poor tolerated in a number of clinical scenarios, necessitating further basic and clinical investigations that emphasize the elucidation of the signal transduction pathways controlled by erythropoietin to direct both successful and safe clinical care.

Triple play: promoting neurovascular longevity with nicotinamide, WNT, and erythropoietin in diabetes mellitus

Oxidative stress is a principal pathway for the dysfunction and ultimate destruction of cells in the neuronal and vascular systems for several disease entities, not promoting the ravages of oxidative stress to any less of a degree than diabetes mellitus. Diabetes mellitus is increasing in incidence as a result of changes in human behavior that relate to diet and daily exercise and is predicted to affect almost 400 million individuals worldwide in another two decades. Furthermore, both type 1 and type 2 diabetes mellitus can lead to significant disability in the nervous and cardiovascular systems, such as cognitive loss and cardiac insufficiency. As a result, innovative strategies that directly target oxidative stress to preserve neuronal and vascular longevity could offer viable therapeutic options to diabetic patients in addition to more conventional treatments that are designed to control serum glucose levels. Here we discuss the novel application of nicotinamide, Wnt signaling, and erythropoietin that modulate cellular oxidative stress and offer significant promise for the prevention of diabetic complications in the nervous and vascular systems. Essential to this process is the precise focus upon diverse as well as common cellular pathways governed by nicotinamide, Wnt signaling, and erythropoietin to outline not only the potential benefits, but also the challenges and possible detriments of these therapies. In this way, new avenues of investigation can hopefully bypass toxic complications, or at the very least, avoid contraindications that may limit care and offer both safe and robust clinical treatment for patients.

The Wnt signaling pathway: aging gracefully as a protectionist?

No longer considered to be exclusive to cellular developmental pathways, the Wnt family of secreted cysteine-rich glycosylated proteins has emerged as versatile targets for a variety of conditions that involve cardiovascular disease, aging, cancer, diabetes, neurodegeneration, and inflammation. In particular, modulation of Wnt signaling may fill a critical void for the treatment of disorders that impact upon both cellular survival and cellular longevity. Yet, in some scenarios, Wnt signaling can become the catalyst for disease development or promote cell senescence that can compromise clinical utility. This double edge sword in regards to the role of Wnt and its signaling pathways highlights the critical need to further elucidate the cellular mechanisms governed by Wnt in conjunction with the development of robust pharmacological ligands that may open new avenues for disease treatment. Here we discuss the influence of the Wnt pathway during cell survival, metabolism, and aging in order for one to gain a greater insight for the novel role of Wnt signaling as well as exemplify its unique cellular pathways that influence both normal physiology and disease.

"Sly as a FOXO": new paths with Forkhead signaling in the brain

The Forkhead transcription factor FOXO3a has emerged as a versatile target for diseases that impact upon neuronal survival, vascular integrity, immune function, and cellular metabolism. Enthusiasm is high to fill a critical treatment void through FOXO3a signaling for several neurodegenerative disorders that include aging, neuromuscular disease, systemic lupus erythematosus, stroke, and diabetic complications. Here we discuss the influence of FOXO3a upon cell survival and longevity, the intricate signal transduction pathways of FOXO3a, insights into present disease models, and the potential clinical translation of FOXO3a signaling into novel therapeutic strategies.

Delayed neurotrophin treatment following deafness rescues spiral ganglion cells from death and promotes regrowth of auditory nerve peripheral processes: effects of brain-derived neurotrophic factor and fibroblast growth factor

The extent to which neurotrophic factors are able to not only rescue the auditory nerve from deafferentation-induced degeneration but also promote process regrowth is of basic and clinical interest, as regrowth may enhance the therapeutic efficacy of cochlear prostheses. The use of neurotrophic factors is also relevant to interventions to promote regrowth and repair at other sites of nerve trauma. Therefore, auditory nerve survival and peripheral process regrowth were assessed in the guinea pig cochlea following chronic infusion of BDNF + FGF(1) into scala tympani, with treatment initiated 4 days, 3 weeks, or 6 weeks after deafferentation from deafening. Survival of auditory nerve somata (spiral ganglion neurons) was assessed from midmodiolar sections. Peripheral process regrowth was assessed using pan-Trk immunostaining to selectively label afferent fibers. Significantly enhanced survival was seen in each of the treatment groups compared to controls receiving artificial perilymph. A large increase in peripheral processes was found with BDNF + FGF(1) treatment after a 3-week delay compared to the artificial perilymph controls and a smaller enhancement after a 6-week delay. Neurotrophic factor treatment therefore has the potential to improve the benefits of cochlear implants by maintaining a larger excitable population of neurons and inducing neural regrowth.

The Src homology 2 domain tyrosine phosphatases SHP-1 and SHP-2: diversified control of cell growth, inflammation, and injury

Interest in the diverse biology of protein tyrosine phosphatases that are encoded by more than 100 genes in the human genome continues to grow at an accelerated pace. In particular, two cytoplasmic protein tyrosine phosphatases composed of two Src homology 2 (SH2) NH2-terminal domains and a C-terminal protein-tyrosine phosphatase domain referred to as SHP-1 and SHP-2 are known to govern a host of cellular functions. SHP-1 and SHP-2 modulate progenitor cell development, cellular growth, tissue inflammation, and cellular chemotaxis, but more recently the role of SHP-1 and SHP-2 to directly control cell survival involving oxidative stress pathways has come to light. SHP-1 and SHP-2 are fundamental for the function of several growth factor and metabolic pathways yielding far reaching implications for disease pathways and disorders such as diabetes, neurodegeneration, and cancer. Although SHP-1 and SHP-2 can employ similar or parallel cellular pathways, these proteins also clearly exert opposing effects upon downstream cellular cascades that affect early and late apoptotic programs. SHP-1 and SHP-2 modulate cellular signals that involve phosphatidylinositol 3-kinase, Akt, Janus kinase 2, signal transducer and activator of transcription proteins, mitogen-activating protein kinases, extracellular signal-related kinases, c-Jun-amino terminal kinases, and nuclear factor-kappaB. Our progressive understanding of the impact of SHP-1 and SHP-2 upon multiple cellular environments and organ systems should continue to facilitate the targeted development of treatments for a variety of disease entities.

Involvement of Ca2+- and cyclic adenosine monophosphate-mediated signaling pathways in photodynamic injury of isolated crayfish neuron and satellite glial cells

To investigate the mechanisms of oxidative injury of neurons and glia, we studied the photodynamic effect on isolated stretch receptor that consists of only two sensory neurons enwrapped by satellite glial cells. Photodynamic therapy (PDT), a potent inducer of oxidative stress, is a prospective method for destruction of brain tumors. PDT induced functional inactivation and necrosis of neurons, necrosis, apoptosis, and proliferation of glial cells. The roles of calmodulin, calmodulin-dependent kinase II, phospholipase C, protein kinases A and C, and phosphodiesterase in these processes were studied by using their inhibitors: fluphenazine, KN-93, D-609, H89, staurosporine, and papaverine, respectively. PDT-induced firing abolishment was enhanced by H89 or papaverine, whereas staurosporine acted oppositely. Fluphenazine or KN-93 reduced necrosis of neurons and glial cells. H89 enhanced necrosis of neurons, whereas staurosporine enhanced necrosis of glial cells. Inhibition of protein kinases A and C enhanced PDT-induced glial apoptosis. Photodynamic gliosis was prevented by KN-93 or staurosporine. These data indicate possible involvement of calmodulin and calmodulin-dependent kinase II in photoinduced necrosis of neurons and glia. Protein kinase C could protect glial cells from necrosis and apoptosis and participate in photoinduced gliosis and loss of neuronal activity. Protein kinase A maintained neuronal firing and protected neurons from photoinduced necrosis and glial cells from apoptosis. Phosphodiesterase reduced necrosis of photosensitized neurons and glia. Thus, Ca(2+)- and cAMP-mediated signaling pathways were involved in photooxidative injury of neurons and glia. Their pharmacological modulation may differently change the efficacy of photodynamic injury of neurons and glial cells.

Oxidative stress biology and cell injury during type 1 and type 2 diabetes mellitus

Diabetes mellitus (DM) affects approximately 170 million individuals worldwide and is expected to alter the lives of at least 366 million individuals within a future span of 25 years. Of even greater concern is the premise that these projections are underestimated since they assume obesity levels will remain constant. Type 1 insulin-dependent DM accounts for only 5-10 percent of all diabetics but represents a highly significant health concern, since this disorder begins early in life and leads to long-term complications. In contrast, Type 2 DM is recognized as the etiology of over 80 percent of all diabetics and is dramatically increasing in incidence as a result of changes in human behavior and increased body mass index. Yet, the pathological consequences of these disorders that involve the both the neuronal and vascular systems are intimately linked through the pathways that mediate oxidative stress. Here we highlight some of the relevant oxidative pathways that determine insulin resistance through reactive oxygen species, mitochondrial dysfunction, uncoupling proteins, and endoplasmic reticulum stress. These pathways are ultimately linked to protein kinase B (Akt) and the insulin signaling pathways that determine the initial onset of glucose intolerance and the subsequent course to apoptotic cell injury. Through the elucidation of these targets, improvement in current strategies as well as the development of future clinical applications can move forward for both the prevention and treatment of Type 1 and Type 2 DM.

Mechanisms of noise-induced hearing loss indicate multiple methods of prevention

Recent research has shown the essential role of reduced blood flow and free radical formation in the cochlea in noise-induced hearing loss (NIHL). The amount, distribution, and time course of free radical formation have been defined, including a clinically significant late formation 7-10 days following noise exposure, and one mechanism underlying noise-induced reduction in cochlear blood flow has finally been identified. These new insights have led to the formulation of new hypotheses regarding the molecular mechanisms of NIHL; and, from these, we have identified interventions that prevent NIHL, even with treatment onset delayed up to 3 days post-noise. It is essential to now assess the additive effects of agents intervening at different points in the cell death pathway to optimize treatment efficacy. Finding safe and effective interventions that attenuate NIHL will provide a compelling scientific rationale to justify human trials to eliminate this single major cause of acquired hearing loss.