Cell imaging and morphology: application to studies of inherited purine metabolic disorders

Cytoprotective effect of Valeriana officinalis extract on an in vitro experimental model of Parkinson disease

Parkinson's disease (PD) is one of the most important neurodegenerative worldwide disorders. The potential cytoprotective effects of aqueous extract of Valeriana officinalis on rotenone-induced apoptosis in human neuroblastoma SH-SY5Y cells were demonstrated. The cytotoxicity, cell viability and analysis of cellular morphology were performed by MTT-tetrazole (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and phase contrast microscopy, respectively. Significant changes in the cellular morphology, and condensation of the cell body could be observed when cells were treated with 300 nM rotenone for 48 h. Three different concentrations of Valeriana officinalis extract were used (0.049, 0.098 and 0.195 mg/mL). These extracts brought about an increase of 7.0 +/- 1.3%, 14.5 +/- 1.3% and 14.5 +/- 3.2% in cell viability. Our results indicated that neuroprotector action of the Valeriana officinalis extract provides support for later studies as they help understanding this drug for the development of cytoprotective various therapies in PD.

A human neuronal tissue culture model for Lesch-Nyhan disease

Mutations in the gene encoding the purine salvage enzyme, hypoxanthine-guanine phosphoribosyltransferase (HPRT) cause Lesch-Nyhan disease, a neurodevelopmental disorder characterized by cognitive, neurological, and behavioral abnormalities. Despite detailed knowledge of the enzyme's function, the key pathophysiological changes that accompany loss of purine recycling are unclear. To facilitate delineating the consequences of HPRT deficiency, four independent HPRT-deficient sublines of the human dopaminergic neuroblastoma, SK-N-BE(2) M17, were isolated by targeted mutagenesis with triple helix-forming oligonucleotides. As a group, these HPRT-deficient cells showed several significant abnormalities: (i) impaired purine recycling with accumulation of hypoxanthine, guanine, and xanthine, (ii) reduced guanylate energy charge and GTP:GDP ratio, but normal adenylate energy charge and no changes in any adenine nucleotide ratios, (iii) increased levels of UTP and NADP+, (iv) reduced DOPA decarboxylase, but normal monoamines, and (v) reduction in cell soma size. These cells combine the analytical power of multiple lines and a human, neuronal origin to provide an important tool to investigate the pathophysiology of HPRT deficiency.

Altered membrane NTPase activity in Lesch-Nyhan disease fibroblasts: comparison with HPRT knockout mice and HPRT-deficient cell lines

Lesch-Nyhan disease (LND) is a rare disorder caused by a defect of an enzyme in the purine salvage pathway, hypoxanthine phosphoribosyl transferase (HPRT). It is still unknown how the metabolic defect translates into the complex neuropsychiatric phenotype characterized by self-injurious behavior, dystonia and mental retardation. There are abnormalities in purine and pyrimidine nucleotide content in HPRT-deficient cells. We hypothesized that altered nucleotide concentrations in HPRT deficiency change G-protein-mediated signal transduction. Therefore, our original study aim was to examine the high-affinity GTPase activity of G-proteins in membranes from primary human skin and immortalized mouse skin fibroblasts, rat B103 neuroblastoma cells and mouse Neuro-2a neuroblastoma cells. Unexpectedly, in membranes from human fibroblasts, B103- and Neuro-2a cells, V(max) of low-affinity nucleoside 5'-triphosphatase (NTPase) activities was decreased up to 7-fold in HPRT deficiency. In contrast, in membranes from mouse fibroblasts, HPRT deficiency increased NTPase activity up to 4-fold. The various systems analyzed differed from each other in terms of K(m) values for NTPs, absolute V(max) values and K(i) values for nucleoside 5'-[beta,gamma-imido]triphosphates. Our data show that altered membrane NTPase activity is a biochemical hallmark of HPRT deficiency, but species and cell-type differences have to be considered. Thus, future studies on biochemical changes in LND should be conducted in parallel in several HPRT-deficient systems.

Imaging system for visualization and numerical analysis of cancer at stomach and skin tissues

Digital imaging of cancerous cells is instrumental not only in determining the characteristic of the cancer but also monitoring the progress of the disease in the follow up of the patient and adapting the treatment, accordingly. Therefore, we have developed an imaging system to display and layout the characteristics of normal and cancerous cells in an automated way. Image processing techniques are performed on the digitized images of stomach and skin tissues, in order to derive the number of cells, area of an individual cell, and average area of the cells in a certain size of an image window.

Hypoxanthine-guanine phosphoribosyltransferase-deficiency produces aberrant neurite outgrowth of rodent neuroblastoma used to model the neurological disorder Lesch Nyhan syndrome

Lesch Nyhan syndrome (LNS) manifests in bizarre and horrific neurological symptoms, the primary cause being a deficiency of the purine salvage enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGPRT). How and why this enzyme deficiency leads to abnormal brain development is unknown. To investigate this phenomenon the present study was designed to examine if the growth of two HGPRT-deficient neuroblastomas, mouse N2aTG and rat B103-4C was different with respect to their corresponding control cell lines, N2a and B103. Data is provided showing that compared to control cell lines, HGPRT-deficient cells proliferated less and exhibited greater morphological complexity. If these abnormalities occur during neurogenesis of human HGPRT-deficient brain neurones, they could profoundly influence central nervous system development and thus, may form the aetiological basis for the symptoms of LNS.

Abnormal development of hypoxanthine-guanine phosphoribosyltransferase-deficient CNS neuroblastoma

Lesch-Nyhan syndrome encompasses a host of neurological symptoms, caused by a deficiency of the purine salvage enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGPRT). How the absence of this enzymes activity affects development of the nervous system is unknown. In this study, we examined the ability of N2aTG, a HGPRT-deficient neuroblastoma and its HGPRT-positive counterpart to proliferate and differentiate at various densities. In summary, N2aTG cells proliferated less and differentiated more than N2a cells, with the former cells exhibiting enhanced sensitivity to the effects of low-density culture. Given the homogeneity of this neuroblastoma cell line and its use in studies of neuronal development, the present study indicates that N2aTG cells may prove a suitable in vitro model for the study of non-dopaminergic neuronal development in Lesch-Nyhan syndrome.