A Double Blind, Randomized Cross-Over Trial of Tyrosine Treatment on Cognitive Function and Psychological Parameters in Severe Hospitalized Anorexia Nervosa Patients.

BACKGROUND: Anorexia nervosa (AN) is characterized by self-induced malnutrition, affecting body image, mood, cognition and survival. Tyrosine, an essential amino acid is the precursor of catecholamines. The use of tyrosine to treat AN is based on experiments on diet restricted mice, in which it increased food consumption, improved cognitive function and elevated brain catecholamines. We evaluated the effect of oral tyrosine administration on the cognition and emotional state of patients with AN. We hypothesized that tyrosine may improve cognitive function without changing body weight, thus "kick-start" nutritional rehabilitation. METHODS: 19 female hospitalized patients with chronic AN were supplemented with L-tyrosine (100 mg/kg/day)/ placebo capsules for a three-week period in a double blind, randomized, cross-over study. Participants were evaluated cognitively and psychologically. RESULTS: Tyrosine shortened reaction time and test duration in memory tasks and improved depressive mood. No side effects were noted with the use of tyrosine. CONCLUSIONS: Tyrosine may improve cognitive function and psychological traits associated with AN.

Propagation of damage in the rat brain following sarin exposure: Differential progression of early processes.

Sarin is an irreversible organophosphate cholinesterase inhibitor and a highly toxic warfare agent. Following the overt, dose-dependent signs (e.g. tremor, hyper secretion, seizures, respiratory depression and eventually death), brain damage is often reported. The goal of the present study was to characterize the early histopathological and biochemical events leading to this damage. Rats were exposed to 1LD50 of sarin (80µg/kg, i.m.). Brains were removed at 1, 2, 6, 24 and 48h and processed for analysis. Results showed that TSPO (translocator protein) mRNA increased at 6h post exposure while TSPO receptor density increased only at 24h. In all brain regions tested, bax mRNA decreased 1h post exposure followed by an increase 24h later, with only minor increase in bcl2 mRNA. At this time point a decrease was seen in both anti-apoptotic protein Bcl2 and pro-apoptotic Bax, followed by a time and region specific increase in Bax. An immediate elevation in ERK1/2 activity with no change in JNK may indicate an endogenous "first response" mechanism used to attenuate the forthcoming apoptosis. The time dependent increase in the severity of brain damage included an early bi-phasic activation of astrocytes, a sharp decrease in intact neuronal cells, a time dependent reduction in MAP2 and up to 15% of apoptosis. Thus, neuronal death is mostly due to necrosis and severe astrocytosis. The data suggests that timing of possible treatments should be determined by early events following exposure. For example, the biphasic changes in astrocytes activity indicate a possible beneficial effects of delayed anti-inflammatory intervention.

AF710B, a Novel M1/σ1 Agonist with Therapeutic Efficacy in Animal Models of Alzheimer's Disease.

We previously developed orthosteric M1 muscarinic agonists (e.g. AF102B, AF267B and AF292), which act as cognitive enhancers and potential disease modifiers. We now report on a novel compound, AF710B, a highly potent and selective allosteric M1 muscarinic and σ1 receptor agonist. AF710B exhibits an allosteric agonistic profile on the M1 muscarinic receptor; very low concentrations of AF710B significantly potentiated the binding and efficacy of carbachol on M1 receptors and their downstream effects (p-ERK1/2, p-CREB). AF710B (1-30 µg/kg, p.o.) was a potent and safe cognitive enhancer in rats treated with the M1 antagonist trihexyphenidyl (passive avoidance impairment). These effects of AF710B involve σ1 receptor activation. In agreement with its antiamnesic properties, AF710B (at 30 nM), via activation of M1 and a possible involvement of σ1 receptors, rescued mushroom synapse loss in PS1-KI and APP-KI neuronal cultures, while AF267B (1 µM) was less potent in PS1-KI and ineffective in APP-KI models, respectively. In female 3xTg-AD mice, AF710B (10 µg/kg, i.p./daily/2 months) (i) mitigated cognitive impairments in the Morris water maze; (ii) decreased BACE1, GSK3ß activity, p25/CDK5, neuroinflammation, soluble and insoluble Aß40, Aß42, plaques and tau pathologies. AF710B differs from conventional σ1 and M1 muscarinic (orthosteric, allosteric or bitopic) agonists. These results highlight AF710B as a potential treatment for Alzheimer's disease (e.g. improving cognitive deficits, synaptic loss, amyloid and tau pathologies, and neuroinflammation) with a superior profile over a plethora of other therapeutic strategies.

Is rivastigmine safe as pretreatment against nerve agents poisoning? A pharmacological, physiological and cognitive assessment in healthy young adult volunteers.

Rivastigmine, a reversible cholinesterase inhibitor, approved as a remedy in Alzheimer's disease, was suggested as pretreatment against nerve agents poisoning. We evaluated the pharmacokinetic, pharmacodynamic, physiologic, cognitive and emotional effects of repeated rivastigmine in young healthy male adults, in a double blind, placebo controlled crossover trial. Three groups completed 3 treatment periods: 0, 1.5 and 3mg twice a day, for a total of 5 intakes. Parameters monitored were: vital signs, ECG, laboratory tests, sialometry, visual accommodation, inspiratory peak flow, and cognitive function tests. Adverse reactions were mild. Peak blood levels and peak cholinesterase inhibition increased with repeated intakes, and high variability and non-linear pharmacokinetics were demonstrated. In addition, two cognitive functions were affected (perceptual speed and dynamic tracking). The complicated pharmacological profile and the high inter-personal variability limit the potential use of rivastigmine as pretreatment for war fighters and first responders.

The beneficial effects of doxycycline, an inhibitor of matrix metalloproteinases, on sulfur mustard-induced ocular pathologies depend on the injury stage.

PURPOSE: Sulfur mustard (SM) induces acute ocular lesions, including erosions and inflammation that may be followed by delayed injuries expressed by epithelial defects and neovascularization (NV). Based on the matrix metalloproteinases (MMPs) activity, we evaluated the clinical and biochemical effects of topical treatment with doxycycline, an MMP inhibitor, targeted to the various injury stages. METHODS: Rabbit eyes were exposed to SM vapor. A clinical follow-up was carried out up to 2 months. Tear fluid and cornea samples were collected at different time points for measurements of MMPs activity by zymography. Efficacy of a post-exposure topical doxycycline (2 mg/ml in phosphate buffer saline, ×4/d), targeted to the different phases of the clinical injury, was evaluated. RESULTS: Elevated MMP-9 and MMP-2 activities were found in all corneas during the acute injury and in vascularized corneas during the delayed pathology. In the tear fluid, high MMP-9 activity and negligible MMP-2 activity were found in all the exposed eyes until after the appearance of the delayed pathology symptoms. Prolonged doxycycline treatment reduced MMP-9 activity in the tear fluid. During the acute phase, doxycycline treatment reduced corneal MMP-9 activity and the severity of the injury. Targeting the delayed pathology, doxycycline was clinically efficient only when treatment began before NV appearance. CONCLUSIONS: This in vivo study showed the involvement of MMP-9 and MMP-2 during different phases of the SM-induced ocular injury, and the potential of doxycycline treatment as a post exposure measure for reducing the acute injury and as a preventive therapy for ameliorating the delayed pathology. The tear fluid provided a non-invasive method for continuous follow-up of MMPs activity and revealed additional beneficial aspects of injury and the treatment.

Endothelial cell damage following sulfur mustard exposure in rabbits and its association with the delayed-onset ocular lesions.

OBJECTIVE: Ocular injuries following exposure to the toxic agent sulfur mustard (SM) are characterized by acute corneal erosions and inflammation of the anterior segment that may be followed by delayed corneal injuries, expressed clinically by neovascularization and epithelial defects. The present study aimed to investigate the effects of SM on corneal endothelium (CE) during the acute and delayed phase in relation to the development of the long-term pathology. METHODS: Rabbit eyes were exposed to SM vapor. A clinical follow-up including pachymetry for measurement of corneal thickness were conducted up to 3 months following exposure. In vivo analysis of corneal endothelium in the central and peripheral cornea was carried out, using a contact specular microscopy. Morphometric analysis of cell area and number of cells was performed, to include the acute and delayed phases. Eyes were taken for histology at different time points following exposure (1 h to 3 months). TUNEL staining (Terminal deoxynucleotidyl transferase dUTP nick end labeling) was conducted for detection of apoptosis during the acute phase. RESULTS: SM induced acute corneal erosions and prolonged anterior segment inflammation. Corneal thickness increased within hours, declined after few days but remained higher compared to baseline value for months after the exposure, indicating a chronic edema. Apoptotic alterations were first observed at 6 h resulting in a significant decline in the number of endothelial cells at 24-48 h following exposure. Healing of the endothelium was relatively fast and at one week the Descemet's membrane was resurfaced, yet, the density and morphology of the cells was often abnormal. Moreover, histological evaluation revealed deformation and enlargement of many cells (polymegathism and pleomorphism), thickening and double layered Descemet's membrane. These changes were more pronounced in corneas displaying delayed pathology. DISCUSSION AND CONCLUSIONS: SM induced apoptotic cell death of endothelial cells that was accompanied by corneal edema. The impaired healing of the endothelium, including the decrease in endothelial cell density was associated with the delayed-onset injuries. Since human corneal endothelium is almost amitotic, endothelium toxicity should be taken into consideration when testing potential treatments against ocular injuries following SM exposure.

Prolonged impairment of corneal innervation after exposure to sulfur mustard and its relation to the development of delayed limbal stem cell deficiency.

PURPOSE: Ocular injuries after exposure to the vesicant sulfur mustard (SM) are characterized by acute corneal erosions and inflammation of the anterior segment that may be followed by delayed limbal stem cell deficiency (LSCD), expressed clinically by corneal neovascularization and epithelial defects. The present study aimed to investigate the involvement of corneal nerves in the development of the delayed LSCD. METHODS: Rabbit eyes were exposed to SM vapor and observed clinically up to 1 month. Morphology and density of corneal nerves were studied in acetylcholinesterase-stained whole-mount corneas at different time points after exposure. Corneal calcitonin gene-related peptide (CGRP) was measured and the relation to clinical symptoms was tested. RESULTS: Degeneration of nerve terminals was observed a few hours after exposure simultaneously with the typical signs of SM ocular toxicity. Although corneal erosions healed within days, the nerves continued to disintegrate under a Wallerian degeneration pattern and their density declined significantly at 1 week in both central and peripheral corneal regions. Sprouting and regenerative nerve fibers were observed later in most of the corneas; however, healing was partial and often abnormal and was correlated with corneal edema. CGRP levels decreased at 24 hours and then increased significantly at 1 to 4 weeks, concomitant with the reinnervation process and development of the late injuries. CONCLUSIONS: The prolonged impairment of corneal nerves, together with chronic inflammation implied by edema, and abnormal increase in CGRP may contribute to a pathological environment for corneal epithelial stem cells, leading to their death and to the development of the SM-induced delayed LSCD.

Magnesium sulfate treatment against sarin poisoning: dissociation between overt convulsions and recorded cortical seizure activity.

Sarin, a potent organophosphate cholinesterase inhibitor, induces an array of toxic effects including convulsions. Many antidotal treatments contain anticonvulsants to block seizure activity and the ensuing brain damage. Magnesium sulfate (MGS) is used to suppress eclamptic seizures in pregnant women with hypertension and was shown to block kainate-induced convulsions. Magnesium sulfate was evaluated herein as an anticonvulsant against sarin poisoning and its efficacy was compared with the potent anticonvulsants midazolam (MDZ) and caramiphen (CRM). Rats were exposed to a convulsant dose of sarin (96 µg/kg, im) and 1 min later treated with the oxime TMB4 and atropine to increase survival. Five minutes after initiation of convulsions, MGS, CRM, or MDZ were administered. Attenuation of tonic-clonic convulsions was observed following all these treatments. However, radio-telemetric electro-corticography (ECoG) monitoring demonstrated sustained seizure activity in MGS-injected animals while this activity was completely blocked by MDZ and CRM. This disrupted brain activity was associated with marked increase in brain translocator protein levels, a marker for brain damage, measured 1 week following exposure. Additionally, histopathological analyses of MGS-treated group showed typical sarin-induced brain injury excluding the hippocampus that was partially protected. Our results clearly show that MGS demonstrated misleading features as an anticonvulsant against sarin-induced seizures. This stems from the dissociation observed between overt convulsions and seizure activity. Thus, the presence or absence of motor convulsions may be an unreliable indicator in the assessment of clinical status and in directing adequate antidotal treatments following exposure to nerve agents in battle field or terror attacks.

Characterization of acute and long-term pathologies of superficial and deep dermal sulfur mustard skin lesions in the hairless guinea pig model.

Sulfur mustard induces severe acute and prolonged damage to the skin and only partially effective treatments are available. We have previously validated the use of hairless guinea pigs as an experimental model for skin lesions. The present study aimed to characterize a model of a deep dermal lesion and to compare it with the previously described superficial lesion. Clinical evaluation of the lesions was conducted using reflectance colorimetry, trans-epidermal water loss and wound area measurements. Prostaglandin E(2) content, matrix metalloproteinase-2 and 9 activity, and histopathology were conducted up to 4 weeks post-exposure. Sulfur mustard skin injury, including erythema and edema, impairment of skin barrier and wounds developed in a dose-dependent manner. Prostaglandin E(2) content and matrix metalloproteinase-2 and 9 activities were elevated during the wound development and the healing process. Histological evaluation revealed severe damage to the epidermis and deep dermis and vesications. At 4 weeks postexposure, healing was not completed: significantly impaired stratum corneum, absence of hair follicles, and epidermal hyperplasia were observed. These results confirm the use of the superficial and deep dermal skin injuries in the hairless guinea pigs as suitable models that can be utilized for the investigation of the pathological processes of acute as well as long-term injuries. These models will be further used to develop treatments to improve the healing process and prevent skin damage and long-term effects.

Efficacy assessment of various anticholinergic agents against topical sarin-induced miosis and visual impairment in rats.

Eye exposure to the organophosphorus (OP) irreversible acetylcholinesterase inhibitor sarin results in long-term miosis and reduction in visual function. Anticholinergic drugs, such as atropine or homatropine, which are used topically in order to counter these effects may produce mydriasis and partial cycloplegia, which may worsen visual performance. This study was aimed to test the efficacy of short-acting anticholinergic drugs against sarin-induced miosis and visual impairment, which will minimally insult vision. Long-Evans rats, exposed topically to various sarin doses from 0 to 10 µg, showed a dose-dependent miosis, which returned to pre-exposure levels within 24-48 h. Tropicamide treatment rapidly widened the miotic effect to a different extent depending on time following treatment and dosage given. Cyclopentolate, however, showed a delayed response that finally widened the pupils in a dose-dependent manner. Atropine treatment showed a rapid widening of the pinpoint pupils exceeding baseline level finally causing mydriasis. Light reflex test showed that the contraction ability of the iris following atropine treatment was impaired, as opposed to the use of tropicamide which facilitated the iris contraction, similar to control. Finally, tropicamide and atropine treatments ameliorated the visual impairment, as opposed to cyclopentolate, which worsened visual performance. Considering that tropicamide treatment against sarin exposure did not cause mydriasis nor did it impair the iris contraction flexibility as a response to light, the use of this drug should be taken into consideration as a first-choice topical treatment against OP intoxication.

Delayed loss of corneal epithelial stem cells in a chemical injury model associated with limbal stem cell deficiency in rabbits.

PURPOSE: Ocular injuries following exposure to the chemical agent sulfur mustard (SM) are characterized by acute corneal erosions and inflammation of the anterior segment that may be followed by delayed Partial Limbal Stem Cell Deficiency (LSCD), expressed clinically by corneal neovascularization and epithelial defects. LSCD may derive from direct destruction of limbal stem cells or indirectly from altered limbal stromal niche. The aim of this study was to investigate the mechanism underlying LSCD in SM injuries, focusing on the effects of the chemical on limbal epithelium. METHODS: Rabbit eyes were exposed to SM vapor and were observed by slit lamp examinations and pachymetry. Eyes were taken for histological and molecular biology evaluations at different time points (4 h-4 weeks), to include acute and delayed injuries. Epithelial stem cells were identified by ABCG2, p63 and by in vivo BrdU labeling for slow cycling cells. RESULTS: Limbal stem cells were not damaged during the acute phase following SM exposure, in contrast to the severe injury of the central corneal epithelium. On the contrary, limbal epithelium became activated, responding to corneal insult with a wound healing process, as shown by histology and by transient elevation of the stem cells markers. Simultaneously, inflammation was taking place in the limbal stroma lasting for weeks. A gradual loss of stem cells was observed later-on (2-4 weeks), associated with typical symptoms of LSCD. CONCLUSIONS: LSCD associated with SM ocular toxicity was not derived from a direct cytotoxic effect on the epithelial stem cells, but apparently from pathological events at the limbal stroma, that produced an abnormal microenvironment for the stem cells, triggering their gradual death. The results, and in particular the absence of a primary damage to the epithelial stem cells, indicate the presence of a therapeutic window for intervention to avoid the development of the delayed LSCD.

Lipopolysaccharide induced protection against sulfur mustard cytotoxicity in RAW264.7 cells through generation of TNF-alpha.

Sulfur mustard (HD), a very potent alkylating agent and lipopolysacchride (LPS), are both well characterized inflammatory factors. We have found that concomitant exposure of murine macrophage cells (RAW264.7) to LPS and HD induced protection against HD induced cytotoxicity. Both HD and LPS induce release of inflammatory markers in RAW264.7 cells. However, there are marked differences in the repertoire of inflammatory factors released by the two toxins: While exposure to HD, induced a dose-dependant death of these cells, no significant change in survival rate was observed following LPS (1-100 ng/ml) exposure. Additionally, LPS elicited a robust nitric oxide (NO) and TNF-alpha secretion whereas HD was practically ineffective. Both toxins increased PGE(2) secretion in a concentration dependent manner. Treatment of HD-exposed RAW264.7 cells with anti-inflammatory drugs such as dexamethazone (5 muM), voltaren (diclofenac) (8 muM) or doxycycline (5 muM), decreased the release of cytokines but had no effect on cell viability. Simultaneous application of LPS (100 ng/ml) and HD (20-100 muM) resulted in an amelioration of HD cytotoxicity. Adding the NO generator S-nitrosoglutathione (GSNO) or inhibiting NO production using L-N(G)-monomethyl Arginine, had no effect on cell viability. Moreover, addition of PGE(2) (20 ng/ml) failed to induce any changes in cell viability under basal or HD-induced toxicity. In contrast, TNF-alpha (20 ng/ml) provided remarkable protection against HD-induced cell death. These findings strongly suggest that LPS exerts its protective action against HD toxicity through the generation of TNF-alpha and may provide better understanding of the mechanism of cytoprotection.

Gastro intestinal tracking and gastric emptying of solid dosage forms in rats using X-ray imaging.

The aim of this research was to study the gastrointestinal transit and gastric emptying of non-disintegrating solid dosage forms in rats using X-ray imaging. Commercial gelatin minicapsules were filled with barium sulfate and enterically coated using Eudragit S100. The capsules were administered orally to rats followed by a solution of iodine based contrast agent iopromide. Images were obtained using a standard X-ray camera and digital film processing. Capsules were followed through the GI tract from the stomach to the small intestine, cecum and large intestine and the capsule location could be easily identified. Gastric emptying of different sized capsules was studied. The effect of fasting and time of administration on gastric retention was also studied. It was found that shortened capsules of 3.5 and 4.8mm length were emptied from the stomach whereas the commercial length 7.18mm capsules were retained. Surprisingly, 2.5h post administration more rats retained the capsules in the stomach in the fasted state than in the fed state. We found that X-ray imaging can be used for simple visualization and localization of solid dosage forms in rats in the fed state using shortened commercial minicapsules on rats.

Ocular injuries following sulfur mustard exposure--pathological mechanism and potential therapy.

Sulfur mustard (SM) is a potent vesicant, known for its ability to cause incapacitation and prolonged injuries to the eyes, skin and respiratory system. The toxic ocular events following sulfur mustard exposure are characterized by several stages: photophobia starting a few hours after exposure, an acute injury phase characterized by inflammation of the anterior segment and corneal erosions and a delayed phase appearing following a clinically silent period (years in human). The late injury appeared in part of the exposed eyes, expressed by epithelial defects and corneal neovascularization (NV), that lead to vision deficits and even blindness. During the last years we have characterized the temporal development of ocular lesions following SM vapor exposure in rabbits and have shown the existence of two sub-populations of corneas, those exhibiting delayed ocular lesions (clinically impaired) and those exhibiting only minor injuries if at all (clinically non-impaired). The aim of the present study was to investigate the pathological mechanism underlying the delayed injury by focusing on the unique characteristics of each sub-population and to test the efficacy of potential treatments. Clinically impaired corneas were characterized by chronic inflammation, increased matrix metalloproteinase (MMP) activity, poor innervation and limbal damage. Moreover, using impression cytology and histology, we identified the delayed lesions as typical for an ocular surface disorder under the category of limbal epithelial stem cell deficiency (LSCD). These results point to therapeutic directions, using anti-inflammatory drugs, MMPs inhibitors, neurotrophic factors and amniotic membrane transplantation. Topical anti-inflammatory drugs, either steroid (Dexamycin, DEX) or non-steroidal anti-infllammatory drug (NSAID, Voltaren Ophtha) were found to be beneficial in ameliorating the initial inflammatory response and in postponing the development of corneal NV, when given during the first week after exposure. When DEX was administered as a symptomatic treatment against NV, a significant regression in the angiogenic process was observed, however, the effect was temporal and blood vessels reappeared after therapy ceased. Chronic administration (8 weeks) of the MMP inhibitor Doxycycline was also effective in attenuation of the acute and delayed injury. Preliminary results, using amniotic membrane transplantation revealed some decrease of corneal edema with no effect on corneal NV. It is suggested that the chronic inflammation and prolonged impairment of corneal innervation are playing a role in the pathogenesis of the delayed LSCD following SM exposure by creating a pathological microenvironment to limbal epithelial stem cells, thus, leading to their slow death and to a second cascade of pathological events eventually resulting in severe long-term injuries. As of today, only topical anti-inflammatory drugs reached the criteria of an applicable efficient post-exposure ocular treatment for SM injuries. Further studies are required to investigate the effects of SM on epithelial stem cells and their involvement in the pathogenesis of the long-term injuries.

Efficacy of antidotal treatment against sarin poisoning: the superiority of benactyzine and caramiphen.

Sarin, a potent cholinesterase inhibitor, induces an array of toxic effects including convulsions and behavioral impairments. We report here on the protection provided by post-exposure antidotal treatments against a lethal dose of sarin (1.2xLD50) by scopolamine, benactyzine, trihexyphenidyl or caramiphen, administered 5, 10 or 20 min after the initiation of convulsions. A mixture of the oxime TMB4 and atropine (TA) was injected 1 min following poisoning a paradigm that may represent a scenario reminiscent of a terror incident. Surviving TA-treated rats exhibited marked tonic-clonic convulsions, weight loss, poor clinical status and abnormal cognitive performance as assessed by the Morris water maze. Additionally, a dramatic increase in the density of peripheral benzodiazepine receptors (PBRs), a faithful marker for neuronal damage, was noted. Animals treated 5 min after the development of toxic signs with benactyzine, trihexyphenidyl or caramiphen demonstrated control levels of PBR values, whereas scopolamine produced binding densities significantly above basal levels. Examined at the 10-min time point, scopolamine and trihexyphenidyl afforded no protection against brain damage and did not differ from TA-injected rats. All four drugs failed to significantly prevent the alterations when applied 20 min after onset of convulsions. Assessment of learning processes yielded similar results, where caramiphen exibited some protection at the 20-min time point. Our results show that caramiphen and benactyzine, agents with combined anticholinergic and antiglutamatergic pharmacological profiles, offer considerable shielding against sarin, even when their administration is delayed.

Neuroprotective effects of the Ras inhibitor S-trans-trans-farnesylthiosalicylic acid, measured by diffusion-weighted imaging after traumatic brain injury in rats.

Ras proteins play a role in receptor-mediated signaling pathways and are activated after traumatic brain injury. S-trans-trans-farnesylthiosalicylic acid (FTS), a synthetic Ras inhibitor, acts primarily on the active, GTP-bound form of Ras and was shown to improve neurobehavioral outcome after closed head injury (CHI) in mice. To gain a better understanding of the neuroprotective mechanism of FTS, we used diffusion-weighted imaging (DWI) in a rat model of CHI. Apparent diffusion coefficients (ADC) and transverse relaxation times (T2) were measured in injured rat brains after treatment with vehicle or FTS (5 mg/kg). Neuroprotection by FTS was also assessed in terms of the neurological severity score. One week after injury, significantly better recovery was observed in the FTS-treated rats than in the controls (p = 0.0191). T2 analysis of the magnetic resonance images revealed no differences between the two groups. In contrast, they differed significantly in ADC, particularly at 24 h post-CHI (p < 0.05): in the vehicle-treated rats ADC had decreased to approximately 26% below baseline, whereas it had increased to about 10% above baseline in the FTS-treated rats. As the magnitude of ADC reduction is strongly linked to blood perfusion deficit, these results suggest that the neuroprotective mechanism of FTS might be related to an improvement in cerebral perfusion. We propose that FTS, which is currently being tested in humans for anti-cancer indications, should also be considered as a new strategy for the management of head injury.

Monitoring drug-induced neurodegeneration by imaging of peripheral benzodiazepine receptors.

Several drugs of abuse are known to produce an array of deleterious effects, including alterations in neuronal circuitry and, ultimately, neuronal degeneration. For instance, methamphetamine was shown to induce substantial nigrostriatal dopaminergic terminal damage, including an increase in glial fibrillary acidic protein, a marker for astrocyte proliferation. Nevertheless, there was almost no attempt to define neurodegeneration by measuring the abundance of reactive microglia. In fact, some investigators fail to differentiate between astrocytes and microglia and claim glial fibrillary acidic protein to be a marker for gliosis. To date, there are numerous methods designed to assess brain neuropathologies resulting from a wide arsenal of insults. Regardless of the cause of neuronal damage, reactive glial cells always appear at and around the site of degeneration. These cells are distinguished by the exceptional abundance of peripheral benzodiazepine receptors (PBRs; omicron3 sites), particularly as compared to surrounding neurons. Measuring the binding of specific ligands to these PBRs (for example, [3H]PK 11195) offers a unique indirect marker for reliable impairment estimation in the central nervous system. Moreover, the availability of agents such as [11C]PK 11195 paved the road to in vivo animal and human brain positron emission tomography scanning, demonstrating inflammation-like processes in several diseases. Additionally, the measurement of increased binding of PBR ligands provides a faithful indicator for the behavioral and cognitive deficits accompanying neuronal injury.

Characterization of early plasma concentrations of midazolam in pigs after administration by an autoinjector.

The treatment of organophosphate-induced poisoning is based mainly on atropine and an oxime. Prompt anticonvulsive intervention is usually also required to terminate the ensuing seizure activity and to prevent delayed permanent brain damage. Midazolam, a water-soluble benzodiazepine agonist, has the advantage of rapid absorption following intramuscular administration. In mass casualty situations, the availability of an autoinjector, filled with midazolam, might be a further advantage. In the present study, the plasma pharmacokinetics of midazolam after administration by an autoinjector was compared with conventional intramuscular (i.m.) administration in two groups of four pigs each. During the first 15 min after injection, significantly higher plasma concentrations of midazolam were detected following autoinjector administration, compared with the i.m. injection. The physiological reflection of the accelerated midazolam absorption was a marked reduction in the time interval required for muscle relaxation, induced by midazolam. It is concluded that a midazolam autoinjector might be helpful in the mass casualty scenario following organophosphate poisoning.

M1 muscarinic agonists can modulate some of the hallmarks in Alzheimer's disease: implications in future therapy.

M1 muscarinic receptors (M1 mAChRs) play a role in an apparent linkage of three major hallmarks of Alzheimer's disease (AD): beta-amyloid (Abeta) peptide; tau hyperphosphorylation and paired helical filaments (PHFs); and loss of cholinergic function conducive to cognitive impairments. We evaluated the M1 muscarinic agonists AF102B (Cevimeline, EVOXAC trade mark : prescribed for Sjøgren's syndrome), AF150(S), and AF267B on some of these hallmarks of AD. Activation of M1 mAChRs with these agonists leads, inter alia, to enhanced secretion of amyloid precursor protein (alpha-APP), (via alpha-secretase activation), to decreased Abeta (via gamma-secretase inhibition), and to inhibition of Abeta- and/or oxidative stress-induced cell death. In several animal models mimicking different aspects of AD, these drugs restored cognitive impairments, and in select cases induced a decrease in brain Abeta elevation, with a high safety margin, following po administration. Notably, in mice with small hippocampi, unlike rivastigmine and nicotine, AF150(S) and AF267B restored cognitive impairments also on escape latency in a Morris water maze paradigm, in reversal learning. Studies from other labs showed that AF102B and talsaclidine (another M1 agonist) decreased cerbrospinal fluid (CSF) Abeta in AD patients following chronic treatment, being the first reported drugs with such a profile. The clinical significance of these studies remains to be elucidated, yet based on in vivo (rabbits) and in vitro studies (cell cultures), our M1 agonists can decrease brain Abeta, owing to a novel and dual complementary effect (e.g., inhibition of gamma-secretase and activation of alpha-secretase). Remarkably, although M1 agonists can decrease CSF Abeta in AD patients, an increased AD-type pathology in Parkinson's disease was recently been associated with chronic antimuscarinic treatment. In another aspect, these agonists decreased tau hyperphosphorylation in vitro and in vivo. Notably, nicotinic agonists or cholinesterase inhibitors increased tau hyperphosphorylation. In summary, the M1 agonists tested are effective on cognition and behavior and show unique disease-modifying properties owing to beneficial effects on major hallmarks of AD. This may place such drugs in the first line of modern AD therapies (e.g., beta- or gamma-secretase inhibitors, vaccines against Abeta, statins, and inhibitors of tau hyperphosphorylation).