COMPARISON OF NEURITE OUTGROWTH WITH NEUROFILAMENT PROTEIN SUBUNIT LEVELS IN NEUROBLASTOMA CELLS FOLLOWING MERCURIC OXIDE EXPOSURE

1. The objectives of the study were to establish that inhibition of neuronal differentiation in culture (assessed by neurite outgrowth) can be used as a broad spectrum in vitro measure of neurotoxicity. 2. To establish whether a rapid measure of neurite outgrowth could be used. Thus the study examined the relationship between the degree of neurite outgrowth assessed directly by image analysis and neurofilament protein subunit levels measured by an ELISA. 3. SKNSH neuroblastoma cells, exposed for up to 6 days to mercuric chloride during initiation and continuation of differentiation, had lower levels of neurofilament proteins than unexposed cells. 4. Preliminary data from parallel examinations of neurite outgrowth assessed by image analysis and neurofilament protein subunit levels assessed by ELISA support a correlation when neurofilament protein levels are decreased by sub-cytotoxic doses of mercuric chloride in SKNSH cells.     

Pyridoxal 5'-phosphate enzymes as targets for therapeutic agents

The vitamin B(6)-derived pyridoxal 5'-phosphate (PLP) is the cofactor of enzymes catalyzing a large variety of chemical reactions mainly involved in amino acid metabolism. These enzymes have been divided in five families and fold types on the basis of evolutionary relationships and protein structural organization. Almost 1.5% of all genes in prokaryotes code for PLP-dependent enzymes, whereas the percentage is substantially lower in eukaryotes. Although about 4% of enzyme-catalyzed reactions catalogued by the Enzyme Commission are PLP-dependent, only a few enzymes are targets of approved drugs and about twenty are recognised as potential targets for drugs or herbicides. PLP-dependent enzymes for which there are already commercially available drugs are DOPA decarboxylase (involved in the Parkinson disease), GABA aminotransferase (epilepsy), serine hydroxymethyltransferase (tumors and malaria), ornithine decarboxylase (African sleeping sickness and, potentially, tumors), alanine racemase (antibacterial agents), and human cytosolic branched-chain aminotransferase (pathological states associated to the GABA/glutamate equilibrium concentrations). Within each family or metabolic pathway, the enzymes for which drugs have been already approved for clinical use are discussed first, reporting the enzyme structure, the catalytic mechanism, the mechanism of enzyme inactivation or modulation by substrate-like or transition state-like drugs, and on-going research for increasing specificity and decreasing side-effects. Then, PLP-dependent enzymes that have been recently characterized and proposed as drug targets are reported. Finally, the relevance of recent genomic analysis of PLP-dependent enzymes for the selection of drug targets is discussed.     

Basal ganglia calcification: a Fahr's disease case report

Idiopathic basal ganglia calcification (IBGC), known as Fahr''s disease, is a rare neurological disorder characterized by metabolic, biochemical, neuroradiological and neuropsychiatric alterations caused by symmetrical and bilateral intracranial calcifications. The disease has, in most cases, an autosomal dominant pattern of inheritance and genetic heterogeneity. Overlap of neuropsychiatric symptoms is common with movement disorders accounted for 55% of the manifestation. Here we present the case of a 58-year-old woman, presenting to the emergency department because of an accidental fall. Her past medical history was unremarkable and she denied any neurological symptoms a part from insomnia and anxiety. Patient was sent to the emergency department to perform a Brain Computed Tomography (CT) exam that showed bilateral symmetrical calcifications in cerebellar white matter, the corpus striatum, the posterior thalami, and the centrum semiovale of both cerebral hemispheres. Beeing a case of IBGC without relevant symptoms, diagnosis was mainly obtained thanks to the characteristics features of CT examination.     

Evaluation of RB gene and cyclin-dependent kinase inhibitors P21 and P27 in pleomorphic xantoastrocytoma

Pleomorphic xantoastrocytoma (PXA) is a rare, circumscribed astrocytic tumor that usually occurs in the superficial cerebral hemispheres in children and young adults. Most patients have a favorable prognosis, but recurrence and malignant transformation have been reported. In diffuse gliomas, approximately one third demonstrate mutations of the RB gene. Low expression level and high activity of p27 are known to constitute an independent prognostic factor in patients with malignant gliomas, while p21 expressions have variable labeling ranges. The molecular and genetic basis for tumorigenesis and progression of PXA are still largely unknown. In this study, 13 PXAs were examined immunohistochemically for pRb, p21, and p27 expression. Nine PXAs expressed homogeneous pRb positivity in the most nuclei of the tumor cells. Four cases showed an abnormal pRb staining pattern. All PXAs were positive for nuclear expression of p21. Diffuse nuclear positivity of p27 was seen in 10 cases, focal in 2, and in 1 case was not present. The cases with focal and negative p27 nuclear expression had few pRb-positive nuclei. The majority of PXAs appear to have preserved pRb, p21, and p27 functions. Additional studies are necessary to investigate whether cases with altered pRb and p27 expressions are associated with increased risk of recurrence or malignant transformation.     

PDGFRA Amplification is Common in Pediatric and Adult High‐Grade Astrocytomas and Identifies a Poor Prognostic Group in IDH1 Mutant Glioblastoma

High‐grade astrocytomas (HGAs), corresponding to World Health Organization grades III (anaplastic astrocytoma) and IV (glioblastoma; GBM), are biologically aggressive, and their molecular classification is increasingly relevant to clinical management. PDGFRA amplification is common in HGAs, although its prognostic significance remains unclear. Using fluorescence in situ hybridization (FISH), the most sensitive technique for detecting PDGFRA copy number gains, we determined PDGFRA amplification status in 123 pediatric and 263 adult HGAs. A range of PDGFRA FISH patterns were identified and cases were scored as non‐amplified (normal and polysomy) or amplified (low‐level and high‐level). PDGFRA amplification was frequent in pediatric (29.3%) and adult (20.9%) tumors. Amplification was not prognostic in pediatric HGAs. In adult tumors diagnosed initially as GBM, the presence of combined PDGFRA amplification and isocitrate dehydrogenase 1 (IDH1)^R132H mutation was a significant independent prognostic factor (P = 0.01). In HGAs, PDGFRA amplification is common and can manifest as high‐level and focal or low‐level amplifications. Our data indicate that the latter is more prevalent than previously reported with copy number averaging techniques. To our knowledge, this is the largest survey of PDGFRA status in adult and pediatric HGAs and suggests PDGFRA amplification increases with grade and is associated with a less favorable prognosis in IDH1 mutant de novo GBMs.     

Diffuse ganglioneuromatosis and plexiform neurofibroma of the urinary bladder: report of a pediatric example and literature review

As an initial manifestation of neurofibromatosis type 1, isolated neurofibroma of the urinary bladder occurs only rarely in the first 2 decades of life. We report a case of a 6-year-old African-American girl who presented in this manner and was found to have a plexiform neurofibroma as well as diffuse ganglioneuromatosis of the urinary bladder. We describe the clinical presentation, diagnostic procedures, and pathologic features encountered. In addition, we review the literature with respect to etiology, current treatment strategies, and the issue of surveillance for this complex lesion occurring in the pediatric population. Neurofibroma of the bladder should be considered in the differential diagnosis of painless hematuria in childhood. Its presentation in such patients warrants a complete evaluation to establish the diagnosis of neurofibromatosis type 1 and begin long-term surveillance for its associated manifestations. At present, there are no established criteria for the treatment of this rare lesion.     

Adenosine A2A receptor activation stimulates collagen production in sclerodermic dermal fibroblasts either directly and through a cross-talk with the cannabinoid system

Systemic sclerosis (SSc) is a connective tissue disease characterised by exaggerated collagen deposition in the skin and visceral organs. Adenosine A2A receptor stimulation (A2Ar) promotes dermal fibrosis, while the cannabinoid system modulates fibrogenesis in vitro and in animal models of SSc. Moreover, evidence in central nervous system suggests that A2A and cannabinoid (CB1) receptors may physically and functionally interact. On this basis, we investigated A2Ar expression and function in modulating collagen biosynthesis from SSc dermal fibroblasts and analysed the cross-talk with cannabinoid receptors. In sclerodermic cells, A2Ar expression (RT-PCR, Western blotting) was evaluated together with the effects of A2A agonists and/or antagonists on collagen biosynthesis (EIA, Western blotting). Putative physical and functional interactions between the A2A and cannabinoid receptors were respectively assessed by co-immuno-precipitation and co-incubating the cells with the unselective cannabinoid agonist WIN55,212-2, and the selective A2A antagonist ZM-241385. In SSc fibroblasts, (1) the A2Ar is overexpressed and its occupancy with the selective agonist CGS-21680 increases collagen production, myofibroblast trans-differentiation, and ERK-1/2 phosphorylation; (2) the A2Ar forms an heteromer with the cannabinoid CB1 receptor; and (3) unselective cannabinoid receptor stimulation with a per se ineffective dose of WIN55,212-2, results in a marked anti-fibrotic effect after A2Ar blockage. In conclusion, A2Ar stimulation induces a pro-fibrotic phenotype in SSc dermal fibroblasts, either directly, and indirectly, by activating the CB1 cannabinoid receptor. These findings increase our knowledge of the pathophysiology of sclerodermic fibrosis also further suggesting a new therapeutic approach to the disease.