Involvement of nitric oxide in acute spinal cord injury: an immunocytochemical study using light and electron microscopy in the rat

Nanodelivery of histamine H3 receptor inverse agonist BF-2649 with H3 receptor antagonist and H4 receptor agonist clobenpropit induced neuroprotection is potentiated by antioxidant compound H-290/51 in spinal cord injury

Military personnel are often victims of spinal cord injury resulting in lifetime disability and decrease in quality of life. However, no suitable therapeutic measures are still available to restore functional disability or arresting the pathophysiological progression of disease in victims for leading a better quality of life. Thus, further research in spinal cord injury using novel strategies or combination of available neuroprotective drugs is urgently needed for superior neuroprotection. In this regard, our laboratory is engaged in developing TiO2 nanowired delivery of drugs, antibodies and enzymes in combination to attenuate spinal cord injury induced pathophysiology and functional disability in experimental rodent model. Previous observations show that histamine antagonists or antioxidant compounds when given alone in spinal cord injury are able to induce neuroprotection for short periods after trauma. In this investigation we used a combination of histaminergic drugs with antioxidant compound H-290/51 using their nanowired delivery for neuroprotection in spinal cord injury of longer duration. Our observations show that a combination of H3 receptor inverse agonist BF-2549 with H3 receptor antagonist and H4 receptor agonist clobenpropit induced neuroprotection is potentiated by antioxidant compound H-290/51 in spinal cord injury. These observations suggests that histamine receptors are involved in the pathophysiology of spinal cord injury and induce superior neuroprotection in combination with an inhibitor of lipid peroxidation H-290/51, not reported earlier. The possible mechanisms and significance of our findings in relation to future clinical approaches in spinal cord injury is discussed.

Nanowired delivery of antibodies to tau and neuronal nitric oxide synthase together with cerebrolysin attenuates traumatic brain injury induced exacerbation of brain pathology in Parkinson's disease

Concussive head injury (CHI) is one of the major risk factors for developing Parkinson's disease in later life of military personnel affecting lifetime functional and cognitive disturbances. Till date no suitable therapies are available to attenuate CHI or PD induced brain pathology. Thus, further exploration of novel therapeutic agents are highly warranted using nanomedicine in enhancing the quality of life of veterans or service members of US military. Since PD or CHI induces oxidative stress and perturbs neurotrophic factors regulation associated with phosphorylated tau (p-tau) deposition, a possibility exists that nanodelivery of agents that could enhance neurotrophic factors balance and attenuate oxidative stress could be neuroprotective in nature. In this review, nanowired delivery of cerebrolysin-a balanced composition of several neurotrophic factors and active peptide fragments together with monoclonal antibodies to neuronal nitric oxide synthase (nNOS) with p-tau antibodies was examined in PD following CHI in model experiments. Our results suggest that combined administration of nanowired antibodies to nNOS and p-tau together with cerebrolysin significantly attenuated CHI induced exacerbation of PD brain pathology. This combined treatment also has beneficial effects in CHI or PD alone, not reported earlier.

Nanowired delivery of dl-3-n-butylphthalide with antibodies to alpha synuclein potentiated neuroprotection in Parkinson's disease with emotional stress

Stress is one of the most serious consequences of life leading to several chronic diseases and neurodegeneration. Recent studies show that emotional stress and other kinds of anxiety and depression adversely affects Parkinson's disease symptoms. However, the details of how stress affects Parkinson's disease is still not well known. Traumatic brain injury, stroke, diabetes, post-traumatic stress disorders are well known to modify the disease precipitation, progression and persistence. However, show stress could influence Parkinson's disease is still not well known. The present investigation we examine the role of immobilization stress influencing Parkinson's disease brain pathology in model experiments. In ore previous report we found that mild traumatic brain injury exacerbate Parkinson's disease brain pathology and nanodelivery of dl-3-n-butylphthalide either alone or together with mesenchymal stem cells significantly attenuated Parkinson's disease brain pathology. In this chapter we discuss the role of stress in exacerbating Parkinson's disease pathology and nanowired delivery of dl-3-n-butylphthalide together with monoclonal antibodies to alpha synuclein (ASNC) is able to induce significant neuroprotection. The possible mechanisms of dl-3-n-butylphthalide and ASNC induced neuroprotection and suitable clinical therapeutic strategy is discussed.

The Dark Side of an Essential Amino Acid: L-Arginine in Spinal Cord Injury

L-arginine is a semi-essential amino acid involved in a variety of physiological processes in the central nervous system (CNS). It is essential in the survival and functionality of neuronal cells. Nonetheless, L-arginine also has a dark side; it potentiates neuroinflammation and nitric oxide (NO) production, leading to secondary damage. Therefore, modulating the L-arginine metabolism is challenging because both detrimental and beneficial effects are dependent on this semi-essential amino acid. After spinal cord injury (SCI), L-arginine plays a crucial role in trauma-induced neuroinflammation and regenerative processes via the two key enzymes: nitric oxide synthase (NOS) and arginase (ARG). Studies on L-arginine metabolism using ARG and NOS inhibitors highlighted the conflicting role of this semi-essential amino acid. Similarly, L-arginine supplementation resulted in both negative and positive outcomes after SCI. However, new data indicate that arginine depletion substantially improves spinal cord regeneration after injury. Here, we review the challenging characteristics of L-arginine metabolism as a therapeutic target after SCI.

Co-Administration of Nanowired Monoclonal Antibodies to Inducible Nitric Oxide Synthase and Tumor Necrosis Factor Alpha Together with Antioxidant H-290/51 Reduces SiO2 Nanoparticles-Induced Exacerbation of Pathophysiology of Spinal Cord Trauma

Military personnel are often exposed to silica dust during combat operations across the globe. Exposure to silica dust in US military or service personnel could cause Desert Strom Pneumonitis also referred to as Al Eskan disease causing several organs damage and precipitate autoimmune dysfunction. However, the effects of microfine particles of sand inhalation-induced brain damage on the pathophysiology of traumatic brain or spinal cord injury are not explored. Previously intoxication of silica nanoparticles (50-60 nm size) is shown to exacerbates spinal cord injury induces blood-spinal cord barrier breakdown, edema formation and cellular changes. However, the mechanism of silica nanoparticles-induced cord pathology is still not well known. Spinal cord injury is well known to alter serotonin (5-hydroxytryptamine) metabolism and induce oxidative stress including upregulation of nitric oxide synthase and tumor necrosis factor alpha. This suggests that these agents are involved in the pathophysiology of spinal cord injury. In this review, we examined the effects of combined nanowired delivery of monoclonal antibodies to neuronal nitric oxide synthase (nNOS) together with tumor necrosis factor alpha (TNF-α) antibodies and a potent antioxidant H-290/51 to induce neuroprotection in spinal cord injury associated with silica nanoparticles intoxication. Our results for the first time show that co-administration of nanowired delivery of antibodies to nNOS and TNF-α with H-290/51 significantly attenuated silica nanoparticles-induced exacerbation of spinal cord pathology, not reported earlier.

Neuroprotective Effects of Nanowired Delivery of Cerebrolysin with Mesenchymal Stem Cells and Monoclonal Antibodies to Neuronal Nitric Oxide Synthase in Brain Pathology Following Alzheimer's Disease Exacerbated by Concussive Head Injury

Concussive head injury (CHI) is one of the major risk factors in developing Alzheimer's disease (AD) in military personnel at later stages of life. Breakdown of the blood-brain barrier (BBB) in CHI leads to extravasation of plasma amyloid beta protein (ΑβP) into the brain fluid compartments precipitating AD brain pathology. Oxidative stress in CHI or AD is likely to enhance production of nitric oxide indicating a role of its synthesizing enzyme neuronal nitric oxide synthase (NOS) in brain pathology. Thus, exploration of the novel roles of nanomedicine in AD or CHI reducing NOS upregulation for neuroprotection are emerging. Recent research shows that stem cells and neurotrophic factors play key roles in CHI-induced aggravation of AD brain pathologies. Previous studies in our laboratory demonstrated that CHI exacerbates AD brain pathology in model experiments. Accordingly, it is quite likely that nanodelivery of NOS antibodies together with cerebrolysin and mesenchymal stem cells (MSCs) will induce superior neuroprotection in AD associated with CHI. In this review, co-administration of TiO2 nanowired cerebrolysin - a balanced composition of several neurotrophic factors and active peptide fragments, together with MSCs and monoclonal antibodies (mAb) to neuronal NOS is investigated for superior neuroprotection following exacerbation of brain pathology in AD exacerbated by CHI based on our own investigations. Our observations show that nanowired delivery of cerebrolysin, MSCs and neuronal NOS in combination induces superior neuroprotective in brain pathology in AD exacerbated by CHI, not reported earlier.

Histamine H3 and H4 receptors modulate Parkinson's disease induced brain pathology. Neuroprotective effects of nanowired BF-2649 and clobenpropit with anti-histamine-antibody therapy

Military personnel deployed in combat operations are highly prone to develop Parkinson's disease (PD) in later lives. PD largely involves dopaminergic pathways with hallmarks of increased alpha synuclein (ASNC), and phosphorylated tau (p-tau) in the cerebrospinal fluid (CSF) precipitating brain pathology. However, increased histaminergic nerve fibers in substantia nigra pars Compacta (SNpc), striatum (STr) and caudate putamen (CP) associated with upregulation of Histamine H3 receptors and downregulation of H4 receptors in human cases of PD is observed in postmortem cases. These findings indicate that modulation of histamine H3 and H4 receptors and/or histaminergic transmission may induce neuroprotection in PD induced brain pathology. In this review effects of a potent histaminergic H3 receptor inverse agonist BF-2549 or clobenpropit (CLBPT) partial histamine H4 agonist with H3 receptor antagonist, in association with monoclonal anti-histamine antibodies (AHmAb) in PD brain pathology is discussed based on our own observations. Our investigation shows that chronic administration of conventional or TiO₂ nanowired BF 2649 (1mg/kg, i.p.) or CLBPT (1mg/kg, i.p.) once daily for 1 week together with nanowired delivery of HAmAb (25μL) significantly thwarted ASNC and p-tau levels in the SNpC and STr and reduced PD induced brain pathology. These observations are the first to show the involvement of histamine receptors in PD and opens new avenues for the development of novel drug strategies in clinical strategies for PD, not reported earlier.

Methamphetamine exacerbates pathophysiology of traumatic brain injury at high altitude. Neuroprotective effects of nanodelivery of a potent antioxidant compound H-290/51

Military personnel are often exposed to high altitude (HA, ca. 4500-5000m) for combat operations associated with neurological dysfunctions. HA is a severe stressful situation and people frequently use methamphetamine (METH) or other psychostimulants to cope stress. Since military personnel are prone to different kinds of traumatic brain injury (TBI), in this review we discuss possible effects of METH on concussive head injury (CHI) at HA based on our own observations. METH exposure at HA exacerbates pathophysiology of CHI as compared to normobaric laboratory environment comparable to sea level. Increased blood-brain barrier (BBB) breakdown, edema formation and reductions in the cerebral blood flow (CBF) following CHI were exacerbated by METH intoxication at HA. Damage to cerebral microvasculature and expression of beta catenin was also exacerbated following CHI in METH treated group at HA. TiO2-nanowired delivery of H-290/51 (150mg/kg, i.p.), a potent chain-breaking antioxidant significantly enhanced CBF and reduced BBB breakdown, edema formation, beta catenin expression and brain pathology in METH exposed rats after CHI at HA. These observations are the first to point out that METH exposure in CHI exacerbated brain pathology at HA and this appears to be related with greater production of oxidative stress induced brain pathology, not reported earlier.

Neuroprotective effects of insulin like growth factor-1 on engineered metal nanoparticles Ag, Cu and Al induced blood-brain barrier breakdown, edema formation, oxidative stress, upregulation of neuronal nitric oxide synthase and brain pathology

Military personnel are vulnerable to environmental or industrial exposure of engineered nanoparticles (NPs) from metals. Long-term exposure of NPs from various sources affect sensory-motor or cognitive brain functions. Thus, a possibility exists that chronic exposure of NPs affect blood-brain barrier (BBB) breakdown and brain pathology by inducing oxidative stress and/or nitric oxide production. This hypothesis was examined in the rat intoxicated with Ag, Cu or Al (50-60nm) nanoparticles (50mg/kg, i.p. once daily) for 7 days. In these NPs treated rats the BBB permeability, brain edema, neuronal nitric oxide synthase (nNOS) immunoreactivity and brain oxidants levels, e.g., myeloperoxidase (MP), malondialdehyde (MD) and glutathione (GT) was examined on the 8th day. Cu and Ag but not Al nanoparticles increased the MP and MD levels by twofold in the brain although, GT showed 50% decline. At this time increase in brain water content and BBB breakdown to protein tracers were seen in areas exhibiting nNOS positive neurons and cell injuries. Pretreatment with insulin like growth factor-1 (IGF-1) in high doses (1μg/kg, i.v. but not 0.5μg/kg daily for 7 days) together with NPs significantly reduced the oxidative stress, nNOS upregulation, BBB breakdown, edema formation and cell injuries. These novel observations demonstrate that (i) NPs depending on their metal constituent (Cu, Ag but not Al) induce oxidative stress and nNOS expression leading to BBB disruption, brain edema and cell damage, and (ii) IGF-1 depending on doses exerts powerful neuroprotection against nanoneurotoxicity, not reported earlier.

Nanodelivery of oxiracetam enhances memory, functional recovery and induces neuroprotection following concussive head injury

Military personnel are the most susceptible to concussive head injury (CHI) caused by explosion, blast or missile or blunt head trauma. Mild to moderate CHI could induce lifetime functional and cognitive disturbances causing significant decrease in quality of life. Severe CHI leads to instant death and lifetime paralysis. Thus, further exploration of novel therapeutic agents or new features of known pharmacological agents are needed to enhance quality of life of CHI victims. Previous reports from our laboratory showed that mild CHI induced by weight drop technique causing an impact of 0.224N results in profound progressive functional deficit, memory impairment and brain pathology from 5h after trauma that continued over several weeks of injury. In this investigation we report that TiO2 nanowired delivery of oxiracetam (50mg/kg, i.p.) daily for 5 days after CHI resulted in significant improvement of functional deficit on the 8th day. This was observed using Rota Rod treadmill, memory improvement assessed by the time spent in finding hidden platform under water. The motor function improvement is seen in oxiracetam treated CHI group by placing forepaw on an inclined mesh walking and foot print analysis for stride length and distance between hind feet. TiO2-nanowired oxiracetam also induced marked improvements in the cerebral blood flow, reduction in the BBB breakdown and edema formation as well as neuroprotection of neuronal, glial and myelin damages caused by CHI at light and electron microscopy on the 7th day after 5 days TiO2 oxiracetam treatment. Adverse biochemical events such as upregulation of CSF nitrite and nitrate, IL-6, TNF-a and p-Tau are also reduced significantly in oxiracetam treated CHI group. On the other hand post treatment of 100mg/kg dose of normal oxiracetam in identical conditions after CHI is needed to show slight but significant neuroprotection together with mild recovery of memory function and functional deficits on the 8th day. These observations are the first to point out that nanowired delivery of oxiracetam has superior neuroprotective ability in CHI. These results indicate a promising clinical future of TiO2 oxiracetam in treating CHI patients for better quality of life and neurorehabilitation, not reported earlier.

Nanodelivery of traditional Chinese Gingko Biloba extract EGb-761 and bilobalide BN-52021 induces superior neuroprotective effects on pathophysiology of heat stroke

Military personnel often exposed to high summer heat are vulnerable to heat stroke (HS) resulting in abnormal brain function and mental anomalies. There are reasons to believe that leakage of the blood-brain barrier (BBB) due to hyperthermia and development of brain edema could result in brain pathology. Thus, exploration of suitable therapeutic strategies is needed to induce neuroprotection in HS. Extracts of Gingko Biloba (EGb-761) is traditionally used in a variety of mental disorders in Chinese traditional medicine since ages. In this chapter, effects of TiO2 nanowired EGb-761 and BN-52021 delivery to treat brain pathologies in HS is discussed based on our own investigations. We observed that TiO2 nanowired delivery of EGb-761 or TiO2 BN-52021 is able to attenuate more that 80% reduction in the brain pathology in HS as compared to conventional drug delivery. The functional outcome after HS is also significantly improved by nanowired delivery of EGb-761 and BN-52021. These observations are the first to suggest that nanowired delivery of EGb-761 and BN-52021 has superior therapeutic effects in HS not reported earlier. The clinical significance in relation to the military medicine is discussed.

Topical application of CNTF, GDNF and BDNF in combination attenuates blood-spinal cord barrier permeability, edema formation, hemeoxygenase-2 upregulation, and cord pathology

Spinal cord injury (SCI) is one of the leading causes of disability in Military personnel for which no suitable therapeutic strategies are available till today. Thus, exploration of novel therapeutic measures is highly needed to enhance the quality of life of SCI victims. Previously, topical application of BDNF and GDNF in combination over the injured spinal cord after 90min induced marked neuroprotection. In present investigation, we added CNTF in combination with BDNF and/or GDNF treatment to examine weather the triple combination applied over the traumatic cord after 90 or 120min could thwart cord pathology. Since neurotrophins attenuate nitric oxide (NO) production in SCI, the role of carbon monoxide (CO) production that is similar to NO in inducing cell injury was explored using immunohistochemistry of the constitutive isoform of enzyme hemeoxygenase-2 (HO-2). SCI inflicted over the right dorsal horn of the T10-11 segments by making an incision of 2mm deep and 5mm long upregulated the HO-2 immunostaining in the T9 and T12 segments after 5h injury. These perifocal segments are associated with breakdown of the blood-spinal cord barrier (BSCB), edema development and cell injuries. Topical application of CNTF with BDNF and GDNF in combination (10ng each) after 90 and 120min over the injured spinal cord significantly attenuated the BSCB breakdown, edema formation, cell injury and overexpression of HO-2. These observations are the first to show that CNTF with BDNF and GDNF induced superior neuroprotection in SCI probably by downregulation of CO production, not reported earlier.

Diabetes exacerbates brain pathology following a focal blast brain injury: New role of a multimodal drug cerebrolysin and nanomedicine

Blast brain injury (bBI) is a combination of several forces of pressure, rotation, penetration of sharp objects and chemical exposure causing laceration, perforation and tissue losses in the brain. The bBI is quite prevalent in military personnel during combat operations. However, no suitable therapeutic strategies are available so far to minimize bBI pathology. Combat stress induces profound cardiovascular and endocrine dysfunction leading to psychosomatic disorders including diabetes mellitus (DM). This is still unclear whether brain pathology in bBI could exacerbate in DM. In present review influence of DM on pathophysiology of bBI is discussed based on our own investigations. In addition, treatment with cerebrolysin (a multimodal drug comprising neurotrophic factors and active peptide fragments) or H-290/51 (a chain-breaking antioxidant) using nanowired delivery of for superior neuroprotection on brain pathology in bBI in DM is explored. Our observations are the first to show that pathophysiology of bBI is exacerbated in DM and TiO₂-nanowired delivery of cerebrolysin induces profound neuroprotection in bBI in DM, not reported earlier. The clinical significance of our findings with regard to military medicine is discussed.

Concussive head injury exacerbates neuropathology of sleep deprivation: Superior neuroprotection by co-administration of TiO2-nanowired cerebrolysin, alpha-melanocyte-stimulating hormone, and mesenchymal stem cells

Sleep deprivation (SD) is common in military personnel engaged in combat operations leading to brain dysfunction. Military personnel during acute or chronic SD often prone to traumatic brain injury (TBI) indicating the possibility of further exacerbating brain pathology. Several lines of evidence suggest that in both TBI and SD alpha-melanocyte-stimulating hormone (α-MSH) and brain-derived neurotrophic factor (BDNF) levels decreases in plasma and brain. Thus, a possibility exists that exogenous supplement of α-MSH and/or BDNF induces neuroprotection in SD compounded with TBI. In addition, mesenchymal stem cells (MSCs) are very portent in inducing neuroprotection in TBI. We examined the effects of concussive head injury (CHI) in SD on brain pathology. Furthermore, possible neuroprotective effects of α-MSH, MSCs and neurotrophic factors treatment were explored in a rat model of SD and CHI. Rats subjected to 48h SD with CHI exhibited higher leakage of BBB to Evans blue and radioiodine compared to identical SD or CHI alone. Brain pathology was also exacerbated in SD with CHI group as compared to SD or CHI alone together with a significant reduction in α-MSH and BDNF levels in plasma and brain and enhanced level of tumor necrosis factor-alpha (TNF-α). Exogenous administration of α-MSH (250μg/kg) together with MSCs (1×10⁶) and cerebrolysin (a balanced composition of several neurotrophic factors and active peptide fragments) (5mL/kg) significantly induced neuroprotection in SD with CHI. Interestingly, TiO₂ nanowired delivery of α-MSH (100μg), MSCs, and cerebrolysin (2.5mL/kg) induced enhanced neuroprotection with higher levels of α-MSH and BDNF and decreased the TNF-α in SD with CHI. These observations are the first to show that TiO₂ nanowired administration of α-MSH, MSCs and cerebrolysin induces superior neuroprotection following SD in CHI, not reported earlier. The clinical significance of our findings in light of the current literature is discussed.

Protein kinase inhibitors in traumatic brain injury and repair: New roles of nanomedicine

Traumatic brain injury (TBI) causes physical injury to the cell membranes of neurons, glial and axons causing the release of several neurochemicals including glutamate and cytokines altering cell-signaling pathways. Upregulation of mitogen associated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) occurs that is largely responsible for cell death. The pharmacological blockade of these pathways results in cell survival. In this review role of several protein kinase inhibitors on TBI induced oxidative stress, blood-brain barrier breakdown, brain edema formation, and resulting brain pathology is discussed in the light of current literature.

Detection of local and remote cellular damage caused by spinal cord and peripheral nerve injury using a heat shock signaling reporter system

Spinal cord and peripheral nerve injury results in extensive damage to the locally injured cells as well as distant cells that are functionally connected to them. Both primary and secondary damage can cause a broad range of clinical abnormalities, including neuropathic pain and cognitive and memory dysfunction. However, the mechanisms underlying these abnormalities remain unclear, awaiting new methods to identify affected cells to enable examination of their molecular, cellular and physiological characteristics. Here, we report that both primary and secondary damage to cells in mouse models of spinal cord and peripheral nerve injury can be detected in vivo using a novel fluorescent reporter system based on the immediate stress response via activation of Heat Shock Factor 1. We also provide evidence for altered electrophysiological properties of reporter-positive secondarily-injured neurons. The comprehensive identification of injured, but surviving cells located both close and at distant locations from the injury site in vivo will provide a way to study their pathophysiology and possibly prevention of their further deterioration.

Withania somniferaphytochemicals confer neuroprotection by selective inhibition of nNos: Anin silicostudy to search potent and selective inhibitors for human nNOS

Neuronal nitric oxide synthase (nNOS or NOS1) is an important therapeutic target for the treatment of various neurological diseases. A major challenge faced in the design of nNOS inhibitors emphasizes on potency in humans and selectivity over other NOS isoforms — eNOS and iNOS. The present structural-based in silico study was carried out to search potent and selective inhibitor for human nNOS from a set of 40 Withania somnifera phytochemicals structure. Ten phytochemicals appear as dual-selective inhibitors of nNOS over both iNOS and eNOS. Here we report five potent and selective human nNOS inhibitors, namely, Chlorogenic Acid, Withanolide B, Withacnistin Pelletierine, and Calystegine B2 based on their selectivity, binding energy and nNOS active site residues interaction profile. These phytochemicals have nNOS selectivity higher than 4-methyl-6-(2-(5-(3-(methylamino)propyl)pyridin-3-yl)-ethyl)pyridin-2-amine inhibitor and have potential as an oral neurotherapeutic agent to combat neurological disorders mediated by nNOS activation.

Low-Level Laser Irradiation Improves Motor Recovery After Contusive Spinal Cord Injury in Rats

This study investigated the therapeutic effects of low-level laser irradiation (LLLI) on the recovery of motor function and its underlying mechanisms in rats with spinal cord injury (SCI). The spinal cord was contused at the T11 level using a New York University impactor. Thirty-eight rats were randomly divided into four groups: LLLI with 0.08 J, 0.4 J, 0.8 J, and sham. We transcutaneously applied at the lesion site of the spinal contusive rats 5 min after injury and then daily for 21 days. The Basso, Beattie and Bresnahan (BBB) locomotor scale and combined behavioral score (CBS) were used to evaluate motor function. The spinal segments of rostral and caudal from the lesion site, the epicenter, and L4-5 were collected from normal and the all groups at 7 days after SCI. The expression of tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) was compared across groups in all regions. In the present study, LLLI with 0.4 J and 0.8 J led to a significant improvement in motor function compared to sham LLLI, which significantly decreased TNF-α expression at the lesion epicenter and reduced iNOS expression in the caudal segment for all LLLI groups and in the L4-5 segments for the 0.4 J and 0.8 J groups when compared to sham LLLI group. Our results demonstrate that transcutaneous LLLI modulate inflammatory mediators to enhance motor function recovery after SCI. Thus, LLLI in acute phase after SCI might have therapeutic potential for neuroprotection and restoration of motor function following SCI.

Cytokine and Growth Factor Activation In Vivo and In Vitro after Spinal Cord Injury

Spinal cord injury results in a life-disrupting series of deleterious interconnected mechanisms encompassed by the primary and secondary injury. These events are mediated by the upregulation of genes with roles in inflammation, transcription, and signaling proteins. In particular, cytokines and growth factors are signaling proteins that have important roles in the pathophysiology of SCI. The balance between the proinflammatory and anti-inflammatory effects of these molecules plays a critical role in the progression and outcome of the lesion. The excessive inflammatory Th1 and Th17 phenotypes observed after SCI tilt the scale towards a proinflammatory environment, which exacerbates the deleterious mechanisms present after the injury. These mechanisms include the disruption of the spinal cord blood barrier, edema and ion imbalance, in particular intracellular calcium and sodium concentrations, glutamate excitotoxicity, free radicals, and the inflammatory response contributing to the neurodegenerative process which is characterized by demyelination and apoptosis of neuronal tissue.

Baclofen or nNOS inhibitor affect molecular and behavioral alterations evoked by traumatic spinal cord injury in rat spinal cord

BACKGROUND CONTEXT

The loss of descending control after spinal cord injury (SCI) and incessant stimulation of Ia monosynaptic pathway, carrying proprioceptive impulses from the muscles and tendons into the spinal cord, evoke exaggerated α-motoneuron activity leading to increased reflex response. Previous results from our laboratory have shown that Ia monosynaptic pathway is nitrergic.

PURPOSE

The aim of this study was to find out whether nitric oxide produced by neuronal nitric oxide synthase (nNOS) plays a role in setting the excitability of α-motoneurons after thoracic spinal cord transection.

STUDY DESIGN

We tested the hypothesis that the inhibition of nNOS in α-motoneurons after SCI could have a neuroprotective effect on reflex response.

METHODS

Rats underwent spinal cord transection at Th10 level followed by 7, 10, and 14 days of survival. The animals were treated with Baclofen (a gamma aminobutyric acid B receptor agonist, 3 μg/two times per day/intrathecally) applied for 3 days from the seventh day after transection; N-nitro-l-arginine (NNLA) (nNOS blocator) applied for the first 3 days after injury (20 mg/kg per day, intramuscularly); NNLA and Baclofen; or NNLA (60 mg/kg/day, single dose) applied on the 10th day after transection. We detected the changes in the level of nNOS protein, nNOS messenger RNA, and nNOS immunoreactivity. To investigate the reflex response to heat-induced stimulus, tail-flick test was monitored in treated animals up to 16 days after SCI.

RESULTS

Our data indicate that Baclofen therapy is more effective than the combined treatment with NNLA and Baclofen therapy. The single dose of NNLA (60 mg/kg) applied on the 10th day after SCI or Baclofen therapy reduced nNOS expression in α-motoneurons and suppressed symptoms of increased reflex activity.

CONCLUSIONS

The results clearly show that increased nNOS expression in α-motoneurons after SCI may be pharmacologically modifiable with Baclofen or bolus dose of nNOS blocker.

Neuroprotection and its molecular mechanism following spinal cord injury

Acute spinal cord injury initiates a complex cascade of molecular events termed ‘secondary injury’, which leads to progressive degeneration ranging from early neuronal apoptosis at the lesion site to delayed degeneration of intact white matter tracts, and, ultimately, expansion of the initial injury. These secondary injury processes include, but are not limited to, inflammation, free radical-induced cell death, glutamate excitotoxicity, phospholipase A₂ activation, and induction of extrinsic and intrinsic apoptotic pathways, which are important targets in developing neuroprotective strategies for treatment of spinal cord injury. Recently, a number of studies have shown promising results on neuroprotection and recovery of function in rodent models of spinal cord injury using treatments that target secondary injury processes including inflammation, phospholipase A₂ activation, and manipulation of the PTEN-Akt/mTOR signaling pathway. The present review outlines our ongoing research on the molecular mechanisms of neuroprotection in experimental spinal cord injury and briefly summarizes our earlier findings on the therapeutic potential of pharmacological treatments in spinal cord injury.

Size- and age-dependent neurotoxicity of engineered metal nanoparticles in rats

Earlier we showed that chronic administration of engineered nanoparticles (NPs) from metals, e.g., Cu, Ag, or Al (50-60 nm, 50 mg/kg, i.p. daily for 1 week) alter blood-brain barrier (BBB) disruption and induce brain pathology in adult rats (age 18 to 22 weeks). However, effects of size-dependent neurotoxicity of NPs in vivo are still largely unknown. In present investigation, we examined the effects of different size ranges of the above-engineered NPs on brain pathology in rats. Furthermore, the fact that age is also an important factor in brain pathology was also investigated in our rat model. Our results showed that small-sized NPs induced the most pronounced BBB breakdown (EBA +480 to 680 %; radioiodine +850 to 1025 %), brain edema formation (+4 to 6 %) and neuronal injuries (+30 to 40 %), glial fibrillary acidic protein upregulation (+40 to 56 % increase), and myelin vesiculation (+30 to 35 % damage) in young animals as compared to controls. Interestingly, the oldest animals (30 to 35 weeks of age) also showed massive brain pathology as compared to young adults (18 to 20 weeks old). The Ag and Cu exhibited greater brain damage compared with Al NPs in all age groups regardless of their size. This suggests that apart from the size, the composition of NPs is also important in neurotoxicity. The very young and elderly age groups exhibited greater neurotoxicity to NPs suggests that children and elderly are more vulnerable to NPs-induced brain damage. The NPs-induced brain damage correlated well with the upregulation of neuronal nitric oxide synthase activity in the brain indicating that NPs-induced neurotoxicity may be mediated via increased production of nitric oxide, not reported earlier.

Conduction failure following spinal cord injury: functional and anatomical changes from acute to chronic stages

In the majority of spinal cord injuries (SCIs), some axonal projections remain intact. We examined the functional status of these surviving axons since they represent a prime therapeutic target. Using a novel electrophysiological preparation, adapted from techniques used to study primary demyelination, we quantified conduction failure across a SCI and studied conduction changes over time in adult rats with a moderate severity spinal contusion (150 kdyn; Infinite Horizon impactor). By recording antidromically activated single units from teased dorsal root filaments, we demonstrate complete conduction block in ascending dorsal column axons acutely (1-7 d) after injury, followed by a period of restored conduction over the subacute phase (2-4 weeks), with no further improvements in conduction at chronic stages (3-6 months). By cooling the lesion site, additional conducting fibers could be recruited, thus revealing a population of axons that are viable but unable to conduct under normal physiological conditions. Importantly, this phenomenon is still apparent at the most chronic (6 month) time point. The time course of conduction changes corresponded with changes in behavioral function, and ultrastructural analysis of dorsal column axons revealed extensive demyelination during the period of conduction block, followed by progressive remyelination. A proportion of dorsal column axons remained chronically demyelinated, suggesting that these are the axons recruited with the cooling paradigm. Thus, using a clinically relevant SCI model, we have identified a population of axons present at chronic injury stages that are intact but fail to conduct and are therefore a prime target for therapeutic strategies to restore function.

Monoclonal antibodies as novel neurotherapeutic agents in CNS injury and repair

Central nervous system (CNS) injury is a complex in which numerous neurochemicals and other vasoactive agents actively contribute towards the development of posttraumatic brain pathology and/or repair mechanisms. A focal trauma to the brain or spinal cord releases several endogenous neurodestructive agents within the CNS, resulting in adverse cellular reactions. Our laboratory is engaged in identifying these endogenous neurodestructive signals in the CNS following injury caused by trauma or hyperthermia. Our observations show that serotonin (5-HT), dynorphin A (Dyn A 1-17), nitric oxide synthase (NOS), and tumor necrosis factor-α (TNF-α) could be potential neurodestructive signals in the CNS injury. Thus, neutralization of these agents using monoclonal antibodies directed against 5-HT, NOS, Dyn A (1-17), and TNF-α in vivo will result in marked neuroprotection and enhance neurorepair after trauma. In addition, a suitable combination of monoclonal antibodies, for example, NOS and TNF-α, when applied 60-90 min after trauma, is capable to enhance neuroprotective ability and thwart cell and tissue injury after spinal cord insult. Taken together, our novel observations suggest a potential use of monoclonal antibodies as suitable therapeutic agents in CNS injuries to achieve neuroprotection and/or neurorepair.

Nanowired drug delivery for neuroprotection in central nervous system injuries: modulation by environmental temperature, intoxication of nanoparticles, and comorbidity factors

Recent developments in nanomedicine resulted in targeted drug delivery of active compounds into the central nervous system (CNS) either through encapsulated material or attached to nanowires. Nanodrug delivery by any means is supposed to enhance neuroprotection due to rapid accumulation of drugs within the target area and a slow metabolism of the compound. These two factors enhance neuroprotection than the conventions drug delivery. However, this is still uncertain whether nanodrug delivery could alter the pharmacokinetics of compounds making it more effective or just longer exposure of the compound for extended period of time is primarily responsible for enhanced effects of the drugs. Our laboratory is engaged in understanding of the nanodrug delivery using TiO(2) nanowires in CNS injuries models, for example, spinal cord injury (SCI), hyperthermia and/or intoxication of nanoparticles with or without other comorbidity factors, that is, diabetes or hypertension in rat models. Our observations suggest that nanowired drug delivery is effective under normal situation of SCI and hyperthermia as evidenced by significant reduction in the blood-brain barrier (BBB) breakdown, brain edema formation, cognitive disturbances, neuronal damages, and brain pathologies. However, when the pathophysiology of these CNS injuries is aggravated by nanoparticles intoxication or comorbidity factors, adjustment in dosage of nanodrug delivery is needed. This indicates that further research in nanomedicine is needed to explore suitable strategies in achieving greater neuroprotection in CNS injury in combination with nanoparticles intoxication or other comorbidity factors for better clinical practices.

NADPH-d and Fos reactivity in the rat spinal cord following experimental spinal cord injury and embryonic neural stem cell transplantation

AIMS

The aim of this study is to determine the role of nitric oxide (NO) in neuropathic pain and the effect of embryonic neural stem cell (ENSC) transplantation on NO content in rat spinal cord neurons following spinal cord injury (SCI).

MAIN METHODS

Ninety adult male Sprague-Dawley rats were divided into 3 groups (n=30, each): control (laminectomy), SCI (hemisection at T12-T13 segments) and SCI+ENSC. Each group was further divided into sub-groups (n=5 each) based on the treatment substance (L-NAME, 75 mg/kg/i.p.; L-arginine, 225 mg/kg/i.p.; physiological saline, SF) and duration (2h for acute and 28 days for chronic groups). Pain was assessed by tail flick and Randall-Selitto tests. Fos immunohistochemistry and NADPH-d histochemistry were performed in segments 2 cm rostral and caudal to SCI.

KEY FINDINGS

Tail-flick latency time increased in both acute and chronic L-NAME groups and increased in acute and decreased in chronic L-arginine groups. The number of Fos (+) neurons decreased in acute and chronic L-NAME and decreased in acute L-arginine groups. Following ENSC, Fos (+) neurons did not change in acute L-NAME but decreased in the chronic L-NAME groups, and decreased in both acute and chronic L-arginine groups. NADPH-d (+) neurons decreased in acute L-NAME and increased in L-arginine groups with and without ENSC transplantation.

SIGNIFICANCE

This study confirms the role of NO in neuropathic pain and shows an improvement following ENSC transplantation in the acute phase, observed as a decrease in Fos(+) and NADPH-d (+) neurons in spinal cord segments rostral and caudal to injury.

Expression of heat shock protein (HSP 72 kDa) during acute methamphetamine intoxication depends on brain hyperthermia: neurotoxicity or neuroprotection?

In the present study, light and electron microscopy were used to examine heat shock protein (HSP 72 kD) expression during acute methamphetamine (METH) intoxication in rats and evaluate its relationships with brain temperature and alterations in a number of other histochemical and morphological parameters. Freely moving rats received METH at the same dose (9 mg/kg, sc) but at different ambient temperatures (23 and 29°C), showing a wide range of brain temperature elevations (37.6-42.5°C); brains were taken for histochemical and morphological evaluations at peak of brain temperature increase. We found that acute METH intoxication induces massive and wide-spread HSP expression in neural and glial cells examined in detail in the cortex, hippocampus, thalamus, and hypothalamus. In each of these structures, the number of HSP-positive cells tightly correlated with brain temperature elevation. The changes in HSP immunoreactivity were also tightly related to alterations in permeability of the blood-brain barrier, acute glial activation, and brain edema assessed by albumin and GFAP immunoreactivity and measuring tissue water content, respectively. While robust and generalized HSP production normally appears to be the part of an adaptive brain response associated with METH-induced metabolic activation, activation of this protective mechanism has its natural limits and could not counteract the damaging effects of oxidative stress, high temperature, and edema--the leading factors of METH-induced neurotoxicity.

Early microvascular reactions and blood-spinal cord barrier disruption are instrumental in pathophysiology of spinal cord injury and repair: novel therapeutic strategies including nanowired drug delivery to enhance neuroprotection

Spinal cord injury (SCI) is a devastating disease that leads to permanent disability of victims for which no suitable therapeutic intervention has been achieved so far. Thus, exploration of novel therapeutic agents and nano-drug delivery to enhance neuroprotection after SCI is the need of the hour. Previous research on SCI is largely focused to improve neurological manifestations of the disease while ignoring spinal cord pathological changes. Recent studies from our laboratory have shown that pathological recovery of SCI appears to be well correlated with the improvement of sensory motor functions. Thus, efforts should be made to reduce or minimize spinal cord cell pathology to achieve functional and cellular recovery to enhance the quality of lives of the victims. While treating spinal cord disease, recovery of both neuronal and non-neuronal cells, e.g., endothelia and glial cells are also necessary to maintain a healthy spinal cord function after trauma. This review focuses effects of novel therapeutic strategies on the role of spinal cord microvascular reactions and endothelia cell functions, i.e., blood-spinal cord barrier (BSCB) in SCI and repair mechanisms. Thus, new therapeutic approach to minimize spinal cord pathology after trauma using antibodies to various neurotransmitters and/or drug delivery to the cord directly by topical application to maintain strong localized effects on the injured cells are discussed. In addition, the use of nanowired drugs to affect remote areas of the cord after their application on the injured spinal cord in thwarting the injury process rapidly and to enhance the neuroprotective effects of the parent compounds are also described in the light of current knowledge and our own investigations. It appears that local treatment with new therapeutic agents and nanowired drugs after SCI are needed to enhance neurorepair leading to improved spinal cord cellular functions and the sensory motor performances.

Role of mitogen-activated protein kinases in the mechanism of oxidant-induced cell swelling in cultured astrocytes

Cytotoxic brain edema, usually a consequence of astrocyte swelling, is an important complication of stroke, traumatic brain injury, hepatic encephalopathy, and other neurological disorders. Although mechanisms underlying astrocyte swelling are not fully understood, oxidative stress (OS) has generally been considered an important factor in its pathogenesis. To better understand the mechanism(s) by which OS causes cell swelling, we examined the potential involvement of mitogen-activated protein kinases (MAPKs) in this process. Cultures exposed to theoxidant H(2)O(2) (10, 25, 50 microM) for different time periods (1-24 hr) significantly increased cell swelling in a triphasic manner. Swelling was initially observed at 10 min (peaking at 30 min), which was followed by cell shrinkage at 1 hr. A subsequent increase in cell volume occurred at approximately 6 hr, and the rise lasted for at least 24 hr. Cultures exposed to H(2)O(2) caused the activation of MAPKs (ERK1/2, JNK and p38-MAPK), whereas inhibition of MAPKs diminished cell swelling induced by 10 and 25 microM H(2)O(2). These findings suggest that activation of MAPKs is an important factor in the mediation of astrocyte swelling following oxidative stress.

A combination of tumor necrosis factor-alpha and neuronal nitric oxide synthase antibodies applied topically over the traumatized spinal cord enhances neuroprotection and functional recovery in the rat

The possibility that neutralization of nitric oxide synthase and tumor necrosis factor alpha (TNF-alpha) in the cord using their antiserum will induce neuroprotection and improve functional outcome following spinal cord injury (SCI) was examined in a rat model. The SCI was induced in rats by a unilateral incision of the right dorsal horn at the T10-11 segments under equithesin anesthesia. TNF-alpha and/or neuronal nitric oxide synthase (nNOS) antibodies were applied over the traumatized spinal cord at 10-90 minutes after injury and functional recovery and cord pathophysiology were examined at five hours. Topical application of TNF-alpha antiserum at 10 min followed by NOS antiserum at 20 min after SCI significantly improved functional recovery and attenuated blood-spinal cord barrier (BSCB) disturbances, edema formation, and cord pathology. These neuroprotective effects were also seen when the NOS antiserum was applied 10 min after injury followed by TNF-alpha antiserum at 30 min after trauma. However, when TNF-alpha antiserum was applied 1 h after injury and NOS antiserum was given either before or after TNF-alpha antiserum, no neuroprotective effects were observed. Interestingly, neuronal injury was tightly correlated with nNOS expression in the cord in antibody treated groups. These novel observations suggest that early blockade of TNF-alpha and nNOS expression within 20-30 min after SCI is beneficial in nature. This indicates that TNF-alpha and nitric oxide play synergistic roles in the pathophysiology of SCI and combined antibodies therapy has added neuroprotective values in spinal trauma.

The effect of aminoguanidine on compression spinal cord injury in rats

The current study was performed to investigate the effect of aminoguanidine (AG) on spinal cord injury (SCI) in rat. AG (75, 150 and 300mg/kg, i.p. respectively ) was administered to rats immediately following SCI. It was found that AG (150mg/kg) significantly reduced spinal cord water content and improved motor function, however, AG at the doses of 75 and 300mg/kg had no effect. Compared to SCI group without treatment, AG at the dosage of 150mg/kg induced a reduction in the permeability of blood-spinal cord barrier (BSCB) after injury 48h (from 59.8+/-5.5microl/g to 39.8+/-3.8microl/g), a 38% decrease of Malondialdehyde (MDA) values and a 1-fold increase of the Glutathione (GSH) levels at 12h after SCI. And the expression of inducible nitric oxide synthase (iNOS) protein reached a peak at 24h after injury, which was significantly attenuated by treatment with AG (150mg/kg). In addition, the expression of AQP4 protein was down-regulated by the treatment of AG (150mg/kg) at 24h after SCI, and the changes still lasted at 48h after injury. Our results indicated that AG could induce spinal cord edema clearance and improve motor function, which could be correlated with antioxidative property, the down-regulation of iNOS and AQP4 protein expression after SCI.

The Italian wall lizard (Podarcis sicula) as a bioindicator of oil field activity

The aim of this study was to develop and to validate a methodology based on biomarker responses and residue analysis on the terrestrial lizard Podarcis sicula to assess the ecotoxicological effects associated with on-shore oil extraction. The oil treatment plant investigated is located in Val d'Agri (southern Italy). Italian wall lizards were sampled on four stations along a transect determined on the basis of prevailing winds downwind of the oil plant. Cytochrome P450 1A1 activities (EROD and BPMO), AChE activity, PAH bile metabolites and contaminant levels (PAHs and trace elements) were measured. Major results in the evaluation of toxicological impact of oil field activity in the Italian wall lizards were obtained for Cd, Hg, total and carcinogenic PAH levels, and PAH metabolites in bile. Results obtained validate, for the first time, P. sicula as a terrestrial bioindicator for the assessment of the toxicological impact of on-shore extraction activity.

Mitigation of peroxynitrite-mediated nitric oxide (NO) toxicity as a mechanism of induced adaptive NO resistance in the CNS

During CNS injury and diseases, nitric oxide (NO) is released at a high flux rate leading to formation of peroxynitrite (ONOO(*)) and other reactive nitrogenous species, which nitrate tyrosines of proteins to form 3-nitrotyrosine (3NY), leading to cell death. Previously, we have found that motor neurons exposed to low levels of NO become resistant to subsequent cytotoxic NO challenge; an effect dubbed induced adaptive resistance (IAR). Here, we report IAR mitigates, not only cell death, but 3NY formation in response to cytotoxic NO. Addition of an NO scavenger before NO challenge duplicates IAR, implicating reactive nitrogenous species in cell death. Addition of uric acid (a peroxynitrite scavenger) before cytotoxic NO challenge, duplicates IAR, implicating peroxynitrite, with subsequent 3NY formation, in cell death, and abrogation of this pathway as a mechanism of IAR. IAR is dependent on the heme-metabolizing enzyme, heme oxygenase-1 (HO1), as indicated by the elimination of IAR by a specific HO1 inhibitor, and by the finding that neurons isolated from HO1 null mice have increased NO sensitivity with concomitant increased 3NY formation. This data indicate that IAR is an HO1-dependent mechanism that prevents peroxynitrite-mediated NO toxicity in motor neurons, thereby elucidating therapeutic targets for the mitigation of CNS disease and injury.

New perspectives for the treatment options in spinal cord injury

Spinal cord injury (SCI) is a serious clinical disorder that leads to lifetime disability for which no suitable therapeutic agents are available so far. Further research is needed to understand the basic mechanisms of spinal cord pathology that results in permanent disability and poses a heavy burden on our society. In the past, a lot of effort was placed on improving functional outcome with the help of various therapeutic agents, however less attention has been paid on the development and propagation of spinal cord pathology over time. Thus, it is still unclear whether improvement of functional outcome is related to spinal cord pathology or vice versa. Few drugs are able to influence functional outcome without having any improvement on cord pathology. Some drugs, however, can lessen cord pathology but fail to influence the functional outcome. The goal of future treatment options for SCI is therefore to find suitable new drugs or a combination of existing drugs and to use various cellular transplants, neurotrophic factors, myelin-inhibiting factors, tissue engineering and nano-drug delivery to improve both the functional and the pathological outcome in the inured patient. This review deals with the key aspects of the latest treatments for SCI and suggests some possible future therapeutic measures to enhance healthcare in clinical situations.

Drug delivery to the spinal cord tagged with nanowire enhances neuroprotective efficacy and functional recovery following trauma to the rat spinal cord

The possibility that drugs attached to innocuous nanowires enhance their delivery within the central nervous system (CNS) and thereby increase their therapeutic efficacy was examined in a rat model of spinal cord injury (SCI). Three compounds--AP173 (SCI-1), AP713 (SCI-2), and AP364 (SCI-5) (Acure Pharma, Uppsala, Sweden)--were tagged with TiO(2)-based nanowires using standard procedure. Normal compounds were used for comparison. SCI was produced by making a longitudinal incision into the right dorsal horn of the T10-T11 segments under Equithesin anesthesia. The compounds, either alone or tagged with nanowires, were applied topically within 5 to 10 min after SCI. In these rats, behavioral outcome, blood-spinal cord barrier (BSCB) permeability, edema formation, and cell injury were examined at 5 h after injury. Topical application of normal compounds in high quantity (10 microg in 20 microL) attenuated behavioral dysfunction (3 h after trauma), edema formation, and cell injury, as well as reducing BSCB permeability to Evans blue albumin and (131)I. These beneficial effects are most pronounced with AP713 (SCI-2) treatment. Interestingly, when these compounds were administered in identical conditions after tagging with nanowires, their beneficial effects on functional recovery and spinal cord pathology were further enhanced. However, topical administration of nanowires alone did not influence trauma-induced spinal cord pathology or motor functions. Taken together, our results, probably for the first time, indicate that drug delivery and therapeutic efficacy are enhanced when the compounds are administered with nanowires.

Antibodies to serotonin attenuate closed head injury induced blood brain barrier disruption and brain pathology

Closed head injury (CHI) often results in profound brain swelling and instant death of the victims due to compression of the vital centers. However, the neurochemical basis of edema formation in CHI is still obscure. Previous studies from our laboratory show that blockade of serotonin synthesis prior to CHI in a rat model attenuates brain edema, indicating a prominent role for serotonin in head injury. Thus, neutralization of endogenous serotonin activity and/or blocking of its receptors will induce neuroprotection in CHI. Since serotonin has more than 14 receptors and selective serotonin antagonists are still not available, we used serotonin antiserum to neutralize its in vivo effects before or after CHI in a rat model. CHI was produced by an impact of 0.224 N on the right parietal skull bone under Equithesin anesthesia by dropping a weight of 114.6 g from a height of 20 cm through a guide tube. This concussive brain injury resulted in blood-brain barrier (BBB) disruption, brain edema formation, and volume swelling at 5 h that were most pronounced in the contralateral cerebral hemisphere. The plasma and brain serotonin levels were increased several-fold at this time. Intracerebroventricular administration of serotonin antiserum (1:20, monoclonal) into the left lateral cerebral ventricle (30 microL in PBS) 30 min before or 30 min (but not 60 min) after CHI significantly attenuated BBB disruption, brain edema formation, volume swelling, and brain pathology. The plasma and brain serotonin levels continued to remain high. These observations are the first to suggest that antiserum to serotonin when administered into the CSF during the early phase of CHI are capable of inducing neuroprotection.

Nitric oxide in the injured spinal cord: synthases cross-talk, oxidative stress and inflammation

Nitric oxide (NO) is a unique informational molecule involved in a variety of physiological processes in the central nervous system (SNS). It has been demonstrated that it can exert both protective and detrimental effects in several diseases states of the CNS, including spinal cord injury (SCI). The effects of NO on the spinal cord depend on several factors such as: concentration of produced NO, activity of different synthase isoforms, cellular source of production and time of release. Basically, it has been shown that low NO concentrations may play a role in physiologic processes, whereas large amounts of NO may be detrimental by increasing oxidative stress. However, this does not explain all the discrepancies evidenced studying the effects of NO in SCI models. The analysis of the different synthase isoforms, of their temporal profile of activation and cellular source has shed light on this topic. Two post-injury time intervals can be defined with reference to the NO production: immediately after injury and several hours-to-days later. The initial immediate peak of NO production after injury is due to the up-regulation of the neuronal NO synthase (nNOS) in resident spinal cord cells. The late peak is due primarily to the activity of inducible NOS (nNOS) produced by inflammatory infiltrating cells. High NO levels produced by up-regulated nNOS and iNOS are neurotoxic; the down-regulation of nNOS corresponds temporally to the expression of iNOS. On the bases of the evidence, therapeutic approaches should be aimed: (1) to reduce the NO-elicited damage by inhibition of specific synthases according to the temporal profile of activation; (2) by maintaining physiologic amount of NO to keep the induction of iNOS.

Contusive spinal cord injury evokes localized changes in NADPH-d activity but extensive changes in Fos-like immunoreactivity in the rat

The histological detection of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d), a marker for nitric oxide-producing cells, was used to evaluate ongoing changes in the neural biochemistry of the rat spinal cord 1 week following contusive spinal cord injury (SCI). In addition, the immunohistochemical detection of the immediate-early gene c-fos was used to identify basal patterns of neural activity at this time. The numbers and laminar locations of NADPH-d- and c-fos-positive cells were examined in spinal segments adjacent to the site of injury (T12-S3) as well as those distant from the injury (C3-C5) in both SCI and un-injured rats. Our data show that contusive SCI results in a significant reduction in NADPH-d labelling in the superficial dorsal horn, and a significant increase in NADPH-d expression in small bipolar neurons and large motoneurons in the ventral horn at the site of the injury. In spinal segments distant to the injury site (C3-C5), NADPH-d activity did not differ from that of uninjured controls. Furthermore, significant reductions in the levels of c-fos expression were observed in SCI rats, in spinal segments both at and distant to the site of injury for all spinal laminae. The only exception was a dramatic increase observed in the sacral parasympathetic nucleus. These data suggest that increased NADPH-d expression is related to conditions specific to the site of injury, whereas the changes in c-fos expression probably indicate more global changes in neuronal activity following SCI.

Spinal cord decompression sickness associated with scuba diving: correlation of immediate and delayed magnetic resonance imaging findings with severity of neurologic impairment—a report on 3 cases

BACKGROUND

There are few reports detailing an association between immediate and delayed changes in MR imaging findings and severity of neurologic impairment in patients with spinal cord DCS. We report on the cases of 3 patients diagnosed with spinal cord DCS presenting with severe neurologic symptoms after scuba diving.

CASE DESCRIPTION

Of 175 patients with DCS referred to the Tokyo Metropolitan Ebara Hospital Department of Neurosurgery, 3 were determined by MR imaging and neurologic examination to have a spinal cord injury. Hyperbaric oxygen, methylprednisolone, and rehabilitation therapies were applied to these patients. We examined whether the severity of the patients' neurologic dysfunction, classified according to Fränkel's grade, was associated with the extent of abnormal signals depicted by spinal MR imaging in these patients at the acute phase and monthly follow-up points. T2-weighted MR imaging performed within 24 hours of the onset of the patients' neurologic symptoms revealed signals of increased intensity located predominantly in the dorsolateral regions, involving spinal segments 1 through 4, and a neurologic examination upon admission revealed severe sensory and motor dysfunction (Fränkel's grade A) in all 3 patients. The abnormal signals on MR images at 1 month postinjury were markedly decreased in size as compared with those at the acute phase. However, neurologic function showed minimal or no improvement (Fränkel's grade A or B).

CONCLUSION

In patients with spinal cord DCS, the improvement in MR imaging findings was not associated with improved clinical status. This discrepancy suggests that intricate pathophysiologic changes, reversible and persistent damage subsequent to initial cord injuries (ie, edematous and neurotoxic lesions), underlie the disease and affect the clinical course.

N-BENZYLOXYCARBONYL-VAL-ALA-ASP-FLUOROMETHYLKETONE REDUCES SEVERITY OF EXPERIMENTAL SPINAL CORD INJURY

The aim of this study was to investigate the effects of N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketones (z-VAD-fmk) on the degree of experimental spinal cord trauma induced by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy. Spinal cord injury in mice resulted in severe trauma characterized by edema, neutrophil infiltration, production of a range of inflammatory mediators, tissue damage, and apoptosis. Treatment of the mice with z-VAD-fmk, a potent broad specific caspase inhibitor, significantly reduced the degree of (1) spinal cord inflammation and tissue injury (histological score), (2) neutrophil infiltration (myeloperoxidase activity), (3) nitrotyrosine formation, and (4) apoptosis (TUNEL staining and Bax and Bcl-2 expression). In a separate set of experiments, z-VAD-fmk significantly ameliorated the recovery of limb function (evaluated by motor recovery score). Taken together, our results clearly demonstrate that treatment with z-VAD-fmk reduces the development of inflammation and tissue injury associated with spinal cord trauma.