Erin Carlton

Intraspinal cord delivery of IGF-I mediated by adeno-associated virus 2 is neuroprotective in a rat model of familial ALS.

BACKGROUND Amyotrophic lateral sclerosis (ALS) is a devastating disease that is characterized by the progressive loss of motor neurons. Patients with ALS usually die from respiratory failure due to respiratory muscle paralysis. Consequently, therapies aimed at preserving segmental function of the respiratory motor neurons could extend life for these patients. Insulin-like growth factor-I (IGF-I) is known to be a potent survival factor for motor neurons. In this study we induced high levels of IGF-I expression in the cervical spinal cord of hSOD1(G93A) rats with intraspinal cord (ISC) injections of an adeno-associated virus serotype 2 vector (CERE-130). This approach reduced the extent of motor neuron loss in the treated segments of the spinal cord. However, a corresponding preservation of motor function was observed in male, but not female, hSOD1(G93A) rats. We conclude that ISC injection of CERE-130 has the potential to protect motor neurons and preserve neuromuscular function in ALS.

Management of the patient with medically refractory epilepsy

Epilepsy imposes a significant clinical, epidemiologic and economic burden on societies throughout the world. Despite the development of more than ten new antiepileptic drugs over the past 15 years, approximately a third of patients with epilepsy remain resistant to pharmacotherapy. Individuals who fail to respond, or respond only partially, continue to have incapacitating seizures. Managing patients with medically refractory epilepsy is challenging and requires a structured multidisciplinary approach in specialized clinics. If the problems related to drug resistance could be resolved, even in part, by improving the pharmacokinetic profile of existing drugs, the economic savings would be remarkable and the time required to design drugs that achieve seizure control would be shorter than the discovery of new targets and molecules was required. A promising approach is the use of corticosteroids that may have a dual beneficial effect. Resective brain surgery remains the ultimate and highly successful approach to multiple drug resistance in epileptic patients.

Fusion of the tetanus toxin C fragment binding domain and Bcl-xL for protection of peripheral nerve neurons.

OBJECTIVE Apoptosis has been shown to play an important role in motor neuron (MN) degeneration in both neurodegenerative disease and peripheral neuropathy. Bcl-xL, an antiapoptotic protein, is down-regulated in these etiologies. The carboxyl-terminal domain of the tetanus toxin heavy chain (Hc) has high affinity for axon terminal binding and uptake into motor and dorsal root ganglion (DRG) neurons. We report the development of a fusion protein between Hc and Bcl-xL to enhance uptake of Bcl-xL by MNs as a strategy for inhibiting peripheral neuronal apoptosis. METHODS The genes for Hc, Bcl-xL, and green fluorescent protein were cloned into an Escherichia coli expression system in 2 different arrangements. Fusion proteins were purified through chromatography. Cultured E15 rat spinal cord MNs and DRG cells were used to demonstrate neuron-specific uptake and retrograde transport of the fusion proteins mediated by Hc. Finally, glutamate-induced apoptosis was used as an in vitro model to measure the antiapoptotic effects of the fusion proteins. RESULTS Bcl-xL fusion proteins were found to bind specifically and undergo uptake into cultured rat spinal MNs. The fusion proteins were also taken up by DRG axonal terminals and transported back to the cell bodies in Campenot compartmentalized chambers (Tyler Research Corp., Edmonton, Canada). Finally, fusion protein application improved cell survival and decreased apoptosis in glutamate-mediated excitotoxicity of the SH-SY5Y neuronal cells. CONCLUSION Hc can be applied as a universal carrier for therapeutic cargo delivery specifically to MNs or DRGs. The fusion proteins between Bcl-xL and Hc constructed in this study might bear applications to the treatment of MN disease, neuropathy, or nerve injury through nerve or intramuscular injection.

Trophic activity of Rabies G protein-pseudotyped equine infectious anemia viral vector mediated IGF-I motor neuron gene transfer in vitro

The present study examines gene delivery to cultured motor neurons (MNs) with the Rabies G protein (RabG)-pseudotyped lentiviral equine infectious anemia virus (RabG.EIAV) vector. RabG.EIAV-mediated beta-galactosidase (RabG.EIAV-LacZ) gene expression in cultured MNs plateaus 120 h after infection. The rate and percent of gene expression observed are titer-dependent (P < 0.001). The rat IGF-I cDNA sequence was then cloned into a RabG.EIAV vector (RabG.EIAV-IGF-I) and was shown to induce IGF-I expression in HEK 293 cells. MNs infected with RabG.EIAV-IGF-I demonstrate enhanced survival compared to MNs infected with RabG.EIAV-LacZ virus (P < 0.01). In addition, IGF-I expression in cultured MNs induced profound MN axonal elongation compared to control virus (P < 0.01). The enhanced motor neuron tropism of RabG.EIAV previously demonstrated in vivo, together with the trophic effects of RabG.EIAV-IGF-I MN gene expression may lend this vector to therapeutic application in motor neuron disease.

Self-harm during first-episode psychosis

We thank Harvey et al for bringing our attention to the frequency of self-harm during first-episode psychosis.1 Our data (which we are submitting for publication) indicates an even greater concern in this population. A retrospective review of all psychotic patients admitted to a child and adolescent psychiatry unit from 2003 to 2006 showed that out of 1500 cases reviewed, 102 patients below the age of 18 years who were identified with first-episode psychosis between the ages of 8 and 18 carried a diagnosis of psychosis not otherwise specified, schizophreniform disorder or schizoid personality disorder. A total of 32% of patients had a recent history of self-harm (suicide attempt) just prior to their admission for initial psychosis. Contrary to Harvey et al we did not find male gender to be associated with a higher incidence of self-harm and violence against others, but it was associated with high severity of the attempt. Interestingly, 28.43% of our sample who had shown violence against others accessed the legal system first and the mental health system second. Poor insight psychosis may pre-dispose those affected to make wrong choices and end up in the legal system before entering the mental health system. Previous non-psychotic psychiatric history was reported by 74 patients. The most frequent comorbidity was attention-deficit hyperactivity disorder (ADHD) followed by intermittent explosive disorder, separation anxiety, oppositional defiant disorder and emotional instability manifested by depression, explosiveness, or violence against self or others. Labile affect is a key symptom when suspecting an organic brain disorder, as are poor attention and motor abnormalities. When psychosis presents earlier in life, are there more physiological factors at play than presented in the third or fourth decade? Future research is needed to detect any differences that trigger psychosis in childhood v. adulthood. Observations that children are often more disinhibited than adults is consistent with this higher percentage of 32% particularly from in-patient services. Our results are double those identified in adult studies. Major depressive disorder (n=36) and ADHD (n=49) were the two most frequent comorbidities in the group who attempted suicide. Patients with longer duration of untreated psychosis had more severe suicide attempts. Although the number of attempts made by females and males in our sample were similar, females were more likely to repeat an attempt and to use less severe methods, which is consistent with prior reports. Our patients more often carried a historical diagnosis for depression prior to admission for psychosis, which may account for our higher rate of suicidal behaviour prior to admission. Duration of untreated psychosis has been an independent indicator of self-harm.1 Our sample demonstrated an interesting pattern with patients with the highest suicidality having had 7 months or more of untreated psychosis. The immature brain continues to develop into young adulthood when myelination, pruning and other neuronal maturation remain incomplete. It is understandable then that there may be a difference in rates of self-harm with even a higher number of cases in children and adolescents. Male gender, negative symptoms and persecutory delusions are clearly linked to greater treatment delay; this could also explain the increased rate in males. The quality of the initial treatment intervention for the first psychotic episode is critical. Each progressive psychotic episode affects brain development, social and family relationships. Investing efforts in improving the approach to treatment of the first psychotic episode may improve the eventual life outcome. There should be a low threshold for hospitalisation of children with psychosis, since the suicide attempt rate was so high in this population. This further supports the importance of a strong psychosocial plan and close follow-up for both patient and family. Perhaps the most critical factor in the treatment of these children is engaging the family early enough to enhance their understanding of the role of medication in addition to close follow-up and the consequences of inadequate or partial treatment.

Overview of Neural Mechanisms in Developmental Disorders

The development of the mammalian brain is both a highly organized and chaotic process that is nothing short of a miracle. The complexity with which the human brain develops from but a mere plate of ectodermal cells is still not fully understood. Numerous disorders have their etiology seeded in abnormal development during the prenatal and perinatal stages of central nervous system (CNS) development. Various signaling molecules and the precisely orchestrated expression and silencing of neural-specific genes may be disrupted in the CNS development of patients suffering from developmental disorders. In this chapter we present an overview of the normal neural mechanisms of mammalian brain development and how errors in this process contribute to developmental disorders. Developmental disorders are defined as those disorders of the CNS that impair normal functioning and development in early childhood. Developmental pathologies encompass various learning disabilities, dyslexias, dyspraxias, metabolic disorders, and anatomical abnormalities, including those that may result from teratogen exposure. Developmental disorders may affect one specific area of development, or may involve numerous areas as in the case of pervasive developmental disorders. More global developmental disorders result from inherent metabolic abnormalities and more recently described immune mediated mechanisms.

ANTIEPILEPTIC DRUGS | Pathways of Drug Diffusion into the Epileptic Brain

The blood–brain barrier (BBB) protects the brain from harmful substances present in the blood stream, while supplying the brain with the nutrients required for proper functioning. The BBB strictly regulates the penetration of drugs into the brain. Failure of such barrier is often associated with CNS pathologies, including epilepsy. Due to the presence of such complex, yet delicate mechanisms of protection, pharmacological targeting of CNS pathologies is challenging. Introduction of pharmaceutical agents for such ends requires new approaches to drug delivery to outwit vascular barriers. Even though numerous antiepileptic drugs (AEDs) are now available, there have been no major improvements in the reduction of the total number of drug-resistant patients. This lack of progress underscores the nonspecificity of the refractory process itself, suggesting that rather general mechanisms may affect the efficacy of all available AEDs.