Ernest Barbosa

N‐acetylcysteine prevents endotoxin‐induced degeneration of oligodendrocyte progenitors and hypomyelination in developing rat brain

Periventricular leukomalacia (PVL), the dominant form of brain injury in premature infants, is characterized by diffuse white matter injury and is associated with cerebral palsy (CP). Maternal and placental infections are major causes of prematurity and identifiable etiology of PVL and CP. Here we have evaluated the therapeutic efficacy of N‐acetylcysteine (NAC), a potent antioxidant and precursor of glutathione, to attenuate lipopolysaccharide (LPS)‐induced white matter injury and hypomyelination in the developing rat brain, an animal model of PVL. Intraperitoneal pretreatment of pregnant female rats with NAC (50 mg/kg), 2 hr prior to administration of LPS at embryonic day 18 (E18), attenuated the LPS‐induced expression of inflammatory cytokines such as tumor necrosis factor‐α, interleukin‐1β, and inducible nitric oxide synthase in fetal rat brains. There were significantly reduced numbers of TUNEL+ nuclei coimmunostained for platelet‐derived growth factor‐αR+ [a surface marker for oligodendrocyte progenitor cells (OPCs)] at E20 in the subventricular zone of fetal rat brain in the NAC + LPS group compared with the untreated LPS group. Interestingly, immunostaining for O4 and O1 as markers for late OPCs and immature oligodendrocytes demonstrated fewer O4+ and O1+ cells in the LPS group compared with the NAC + LPS and control groups. Consistent with O4+/O1+ cell counts, the expression of myelin proteins such as myelin basic protein, proteolipid protein, and 2′3′‐cyclic nucleotide phosphodiesterase, including transcription factors such as MyT1 and Gtx, was less in the LPS group at late postnatal days, indicating severe hypomyelination in the developing rat brain when compared with NAC + LPS and control groups. Collectively, these data support the hypothesis that NAC may provide neuroprotection and attenuate the degeneration of OPCs against LPS evoked inflammatory response and white matter injury in developing rat brain. Moreover, these data suggest the possible use of NAC as a treatment for pregnant women with maternal or placental infection as a means of minimizing the risk of PVL and CP.

Attenuation of Acute Inflammatory Response by Atorvastatin After Spinal Cord Injury in Rats

Spinal cord injury (SCI) is a devastating and complex clinical condition involving proinflammatory cytokines and nitric oxide toxicity that produces a predictable pattern of progressive injury entailing neuronal loss, axonal destruction, and demyelination at the site of impact. The involvement of proinflammatory cytokines and inducible nitric oxide synthase (iNOS) in exacerbation of SCI pathology is well documented. We have reported previously the antiinflammatory properties and immunomodulatory activities of statins (3‐hydroxy‐3‐methylglutaryl [HMG]‐CoA reductase inhibitors) in the animal model of multiple sclerosis, experimental allergic encephalitis (EAE). The present study was undertaken to investigate the efficacy of atorvastatin (Lipitor; LP) treatment in attenuating SCI‐induced pathology. Immunohistochemical detection and real‐time PCR analysis showed increased expression of iNOS, tumor necrosis factor α (TNFα) and interleukin 1β (IL‐1β) after SCI. In addition, neuronal apoptosis was detected 24 hr after injury followed by a profound increase in ED1‐positive inflammatory infiltrates, glial fibrillary acidic protein (GFAP)‐positive reactive astrocytes, and oligodendrocyte apoptosis by 1 week after SCI relative to control. LP treatment attenuated the SCI‐induced iNOS, TNFα, and IL‐1β expression. LP also provided protection against SCI‐induced tissue necrosis, neuronal and oligodendrocyte apoptosis, demyelination, and reactive gliosis. Furthermore, rats treated with LP scored much higher on the locomotor rating scale after SCI (19.13 ± 0.53) than did untreated rats (9.04 ± 1.22). This study therefore reports the beneficial effect of atorvastatin for the treatment of SCI‐related pathology and disability.

Post-trauma Lipitor treatment prevents endothelial dysfunction, facilitates neuroprotection, and promotes locomotor recovery following spinal cord injury

We have previously reported neuroprotection in spinal cord injury (SCI) by Lipitor [atorvastatin (AT)]‐pre‐treatment. Though informative, pre‐treatment studies find only limited clinical application as trauma occurrence is unpredictable. Therefore, this study investigates the efficacy of AT treatment post‐SCI. In a rat model of contusion‐SCI resulting in complete hindlimb paralysis, AT treatment (5 mg/kg; gavage) was begun 2, 4, or 6 h post‐SCI followed by a once daily dose thereafter for 6 weeks. While the placebo vehicle (VHC)‐SCI rats showed substantial functional deficit, AT‐SCI animals exhibited significant functional recovery. AT diminished injury‐induced blood–spinal cord barrier (BSCB) dysfunction with significantly reduced infiltration and tumor necrosis factor‐α/interleukin‐1β/inducible nitric oxide synthase expression at site of injury. BSCB protection in AT‐SCI was attributable to attenuated matrix metalloproteinase‐9 (MMP9) expression – a central player in BSCB disruption. Furthermore, endothelial MMP9 expression was found to be RhoA/ROCK pathway‐mediated and regulated by AT through an isoprenoid‐dependent mechanism. Attenuation of these early inflammatory events reduced secondary damage. Significant reduction in axonal degeneration, myelin degradation, gliosis, and neuronal apoptosis with resultant enhancement in tissue sparing was observed in AT‐SCI compared with VHC‐SCI. In summary, this novel report presenting the efficacy of post‐injury AT treatment might be of critical therapeutic value as effective treatments are currently unavailable for SCI.

Correlation of very long chain fatty acid accumulation and inflammatory disease progression in childhood X-ALD:: implications for potential therapies

This study was designed to understand the role of inflammatory mediators involved in the neurobiology of childhood adrenoleukodystrophy (cALD) by comparing the differential expression of the inflammatory mediators with metabolite very long chain fatty acids that accumulate in this disease. Histopathological examinations indicated extensive demyelination and accumulation of infiltrates in perivascular cuffs in plaque area (PA) and inflammatory area (IA) compared to normal looking area (NLA) of the cALD brain and controls. The PA had excessive accumulation of cholesterol ester (25-30-fold), VLC fatty acids (8-12-fold), and exhaustive depletion of cholesterol (60-70%) and sphingomyelin (50-55%) in comparison to controls. The mRNA expression of cytokines (IL-1alpha, IL-2, IL-3, IL-6, TNF-alpha, and GM-CSF), chemokines (CCL2, -4, -7, -11, -16, -21, -22, CXCL1, CX3CL1, and SDF-2) and iNOS in IA was significantly increased compared to NLA of the cALD and controls determined by gene array, semiquantitative RT-PCR, and immunohistochemistry. These results indicate that accumulation of VLC fatty acid contents in membrane domains associated with signal transduction pathways may trigger the inflammatory process through activation of resident glial cells (microglia and astrocytes) resulting in loss of myelin and oligodendrocytes.

The use of hypothermia: a role in the treatment of neonatal asphyxia?

Perinatal asphyxia remains one of the most devastating neurologic processes. Although the understanding of the pathophysiology after perinatal asphyxia is extensive, there are few therapeutic interventions available to prevent or even mitigate the devastating process that unfolds after injury. The search for a safe and efficacious therapy has prompted scientists and clinicians to consider various promising therapies. One such therapy is therapeutic hypothermia. On the basis of adult, pediatric, and animal research, there is increasing evidence to suggest that therapeutic hypothermia may be an effective intervention to lessen the secondary neuronal injury that ensues after a hypoxic-ischemic insult. In this article the historic and modern-day uses of therapeutic hypothermia are first reviewed. The pathophysiology of neonatal asphyxia is examined next, with emphasis on the changes that occur when therapeutic hypothermia is implemented. Potential side-effects of the therapy in the neonate and the debate over systemic vs selective hypothermia are discussed. Lastly, although hypothermia as a potential treatment modality for neonates with hypoxic-ischemic encephalopathy is supported by numerous studies, the need for well-designed multicenter trials with detailed patient entry criteria and therapeutic conditions is emphasized.

Use of the pediatric symptom checklist in the pediatric neurology population

The purpose of this study was to evaluate the effectiveness of the Pediatric Symptom Checklist (PSC) as a mental health screening instrument in a busy pediatric neurology population in comparison with more lengthy, time-consuming assessment methods. One hundred two children were screened using the PSC. PSC results were compared with scores on the Child Behavior Checklist (CBCL), results from structured interviews, and ratings of adaptive functioning using the Childrens Global Assessment Scale (CGAS). Thirty-nine of the patients (38%) scored 63 or above on the CBCL, indicating psychosocial impairment. Using a cutoff score of 22, the PSC correctly identified 35 of these 39 positive cases (sensitivity 89.7) and 48 of the 63 children with CBCL scores below 63 (specificity 76.2). CGAS scores were significantly negatively correlated with PSC scores (r = -0.60, P < 0.05). The PSC correctly identified 85.9% of children who scored 70 or below on the CGAS. Among the 53 children with psychiatric diagnoses on the basis of the interview, 41 scored above the cutoff of 22 on the PSC. Results suggest that the PSC is an efficient and accurate screen for identification of mental health problems in the pediatric neurology population.

Molecular cloning and sequencing of human palmitoyl-CoA ligase and its tissue specific expression

A complimentary DNA clone encoding the entire human palmitoyl-CoA ligase has been isolated from a liver cDNA library and sequenced in its entirety. The predicted product is a 699 amino acid protein. Southern analysis utilizing the human palmitoyl-CoA ligase gene as a probe revealed varying degrees of similarity amongst various mammalian species. The palmitoyl-CoA ligase gene is highly expressed in liver, heart, skeletal muscle and kidney, and to a lesser extent in brain, lung, placenta and pancreas. The expression of palmitoyl-CoA ligase in various tissue parallels the function of this enzyme in the metabolism of fatty acids in these tissues.

Restoration of phytanic acid oxidation in Refsum disease fibroblasts from patients with mutations in the phytanoyl-CoA hydroxylase gene.

Refsum disease (RD) is biochemically characterized by the excessive accumulation of phytanic acid in tissues and body fluids due to deficiency of phytanoyl‐CoA hydroxylase (PAHX). In this study, we screened three RD patients and identified a novel deletion (88 amino acids), and a missense mutation (Arg275Trp) in the previously reported PAHX cDNA (Jansen et al., 1997; Mihalik et al., 1997). Moreover, transfection of skin fibroblasts from two RD patients with wild‐type PAHX gene restored the activity for α‐oxidation of phytanic acid. Southern analysis on a somatic cell hybrid panel detected the PAHX gene on chromosome 10, corroborating radiation hybrid and homozygosity mapping data (Mihalik et al., 1997; Nadal et al., 1995).