Lymphangiogenesis: implications for diagnosis, treatment, and prognosis in patients with melanoma.

Disease course in melanoma often cannot be accurately predicted by means of the prognostic factors usually considered in patients with melanoma; therefore, new factors are clearly needed. Increasingly robust scientific evidence shows that tumor lymph vessels play a key role in melanoma that metastasizes by lymphatic and hematogenous pathways. We review current knowledge and examine the implications of lymphangiogenesis in the diagnosis, treatment, and prognosis of patients with melanoma.

Recurrent Aphthous Stomatitis. / Aftosis oral recidivante.

Recurrent aphthous stomatitis is a chronic inflammatory disease of the oral mucosa. It is characterized by painful mouth ulcers that cannot be explained by an underlying disease. Recurrent oral mucosal ulcers require a proper differential diagnosis to rule out other possible causes before recurrent aphthous stomatitis is diagnosed. The condition is common, with prevalence rates ranging from 5 to 60% in different series. Its pathogenesis is unknown, but multiple factors are considered to play a part. There are no standardized treatments for this condition and none of the treatments are curative. The goal of any treatment should be to alleviate pain, reduce the duration of ulcers, and prevent recurrence.

Organic matter geochemical signatures (TOC, TN, C/N ratio, δ13C and δ15N) of surface sediment from lakes distributed along a climatological gradient on the western side of the southern Andes.

Paleolimnological studies in western South America, where meteorological stations are scarce, are critical to obtain more realistic and reliable regional reconstructions of past climate and environmental changes, including vegetation and water budget variability. However, climate and environmental geochemical indicators must be tested before they can be applied with confidence. Here we present a survey of lacustrine surface sediment (core top, 0 to ~1cm) biogeochemical proxies (total organic carbon [TOC], total nitrogen [TN], carbon/nitrogen ratio [C/N ratio] and bulk organic δ13C and total δ15N) from a suite of 72 lakes spanning the transition from a Mediterranean climate with a patchwork of cultivated vegetation, pastureland, and conifers in central Chile to a rainy temperate climate dominated by broadleaf deciduous and evergreen forest further south. Sedimentary data are compared to the latitudinal and orographic climatic trends of the region based on the climatology (precipitation and temperature) produced with Climate Forecast System Reanalysis (CFSR) data and the modern Southern Hemisphere Westerly Winds (SWW) location. The geochemical data show inflection points at ~42°S latitude and ~1500m elevation that are likely related to the northern limit of influence of the SWW and elevation of the snow line, respectively. Overall the organic proxies were able to mimic climatic trends (Mean Annual Precipitation [MAP] and temperature [MAT]), indicating that they are a useful tool to be included in paleoclimatological reconstruction of the region.

Nicotinamide adenine dinucleotides mimic adenosine inhibition on synaptic transmission by decreasing glutamate release in rat hippocampal slices.

To assess the possible inhibitory action of nicotinamide adenine dinucleotides on the synaptic release of glutamate, electrophysiological and biochemical experiments were performed on rat hippocampal slices. Perfusion of adenosine, beta-nicotinamide adenine dinucleotide (NAD) or beta-nicotinamide adenine dinucleotide phosphate (NADP), reversibly inhibited the field excitatory postsynaptic potentials (fEPSP). Dose-response curves for their inhibitory action showed that these three substances had a similar potency in the range of concentrations from 0.1 microM to 100 microM. NADP and adenosine (100 microM) halved the K(+)-induced release of endogenous glutamate and aspartate, leaving gamma-amino-butyric acid (GABA) levels unchanged. 3-Isobutyl-1-methylxanthine (IBMX) 200 microM, an antagonist of the P1-purinoreceptors, antagonized the depressant effects of these coenzymes on both fEPSP and also on amino acid release. Based on these results we propose that nicotinamide adenine dinucleotides, similar to adenosine, inhibit excitatory synaptic transmission in the rat hippocampus by decreasing glutamate release from synaptic terminals.

Anion exchanger AE1 as a candidate pathway for taurine transport in rat erythrocytes.

Taurine has been shown to act as an osmolyte during the regulatory volume decrease process in a variety of cell types. The nature of the taurine efflux carrier is thought to consist of a diffusional pathway with pharmacological properties similar to a chloride channel or through an anion exchanger. We propose that taurine is a substrate of the anion exchanger AE1, also called band 3. Experiments were performed in rat-erythrocytes, which express large amounts of band 3. Taurine uptake and efflux transport experiments were determined in the presence of inhibitors of anion carriers and chloride channels. Both taurine uptake and efflux were inhibited by band 3 inhibitors 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS), niflumic acid, or furosemide. Moreover, DIDS competes with taurine at a common binding site in the uptake process. Specific inhibitors of the electroneutral cotransport as well as inhibitors of the chloride channels were ineffective in blocking taurine transport. Thus we suggest that band 3 may be the protein responsible for taurine transport in rat erythrocytes.

Glutamate and antimitotic agents induce differentiation, p53 activation, and apoptosis in rodent neostriatal cell lines immortalized with the tsA58 allele of SV40 large T antigen.

The tsA58 allele of SV40 large T antigen has the ability to immortalize cells, which is thought to be due, in part, to binding of p53 protein by T antigen at 33 degrees C. At the nonpermissive temperature (39.5 degrees C), it is thought that p53 is released, inducing growth arrest, vulnerability to apoptosis, and loss of the immortal phenotype. In cell lines derived from the rat neostriatum immortalized with tsA58, the toxic agents Adriamycin, cytosine arabinoside, and glutamate induced apoptosis and increased p53 activity and differentiation. The apoptosis and p53-inducing effects of the drugs were not greater at 39.5 degrees C compared to 33 degrees C, suggesting that p53 is not effectively blocked even at 33 degrees C. Growth arrest was not induced under most treatment conditions despite p53 induction. On the other hand, process extension was enhanced at 39.5 degrees C compared to 33 degrees C. Therefore, these cell lines are temperature sensitive with respect to differentiation, but not growth regulation or apoptosis.

N18-RE-105 cells: differentiation and activation of p53 in response to glutamate and adriamycin is blocked by SV40 large T antigen tsA58.

Process extension was induced in cells of the N18-RE-105 neuroblastoma-retinal hybrid line by toxic agents, including glutamate and the p53-inducing anticancer agents adriamycin and etoposide. Both adriamycin and glutamate activated p53 as measured by a plasmid transfection assay. It was therefore hypothesized that SV40 large T antigen, which binds p53, would interfere with cellular differentiation. To test this hypothesis, the temperature-sensitive form of SV40 large T was transduced into N18-RE-105 cells by retroviral infection. SV40 large T-infected cells became de-differentiated, grew in tightly-packed colonies, lost expression of neurofilament, and lost the ability to differentiate in response to glutamate and adriamycin. The de-differentiating effect of SV40 large T antigen may be due to binding and inactivation of cellular proteins, such as p53, p107, p130, p300, and retinoblastoma protein, which are important in cellular growth and differentiation. It is suggested that p53 may play a role in cellular differentiation, perhaps under unusual circumstances involving stress or cytotoxicity.

Taurine release evoked by NMDA receptor activation is largely dependent on calcium mobilization from intracellular stores.

It is known that the activation of N-methyl-D-aspartate (NMDA) receptors leads to an increase in extracellular taurine concentration in different brain regions. The mechanism that mediates this effect is not totally understood. In this study, rat hippocampal slices were used to determine the dependence of NMDA-induced taurine release on extracellular calcium and/or on calcium mobilization from intracellular stores. NMDA was administered through a microdialysis probe inserted into the slice, at the level of CA1 stratum radiatum, which was also used to collect amino acids from the extracellular space. Field potentials evoked by stimulation of the Schaffer collaterals and recorded in the stratum pyramidale of CA1 were used as a control of NMDA receptor activation. NMDA induced a marked increase in extracellular taurine levels and a decrease in field potential amplitude, and both effects were suppressed in the presence of MK-801, a blocker of the NMDA receptor-linked channel. Dantrolene, an inhibitor of calcium release from intracellular stores, partially inhibited the extracellular taurine increase, while 2-nitro-4-carboxyphenyl-N,N-diphenyl carbamate (NCDC), an inhibitor of phosphatidylinositol-specific phospholipase C activation, had no effect. Removal of extracellular calcium diminished, but did not abolish, the extracellular taurine increase caused by NMDA. The remaining taurine response was totally suppressed by dantrolene, and also by NCDC. These results demonstrate that the release of taurine induced by NMDA receptor activation is triggered by the increase in cytoplasmic calcium concentration. We suggest that, under physiological conditions, calcium influx provides the signal for NMDA-induced taurine release, which is amplified by calcium-dependent calcium mobilization from intracellular stores.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro properties of a newly established medulloblastoma cell line, MCD-1.

Medulloblastomas are poorly differentiated brain tumors believed to arise from primitive pleuripotential stem cells, and tend to express mixed neuronal and glial properties. In the present study, we examined immunohistochemical and neurotransmitter phenotypic properties in a newly established medulloblastoma cell line, MCD-1. MCD-1 cells were immortal, not contact-inhibited, but did not grow in soft agar. Immunohistochemical studies showed positive staining for neurofilament protein (NF), neuron-specific enolase (NSE), synaptophysin, MAP 2, tau, NCAM 180, vimentin, and S-100 protein. The cells expressed specific uptake of glutamate, serotonin, and choline, but not GABA or dopamine. A significant increase in process extension was seen in response to agents that enhance intracellular cyclic AMP, especially 3-isobutyl-1-methylxanthine (IBMX). Process formation induced by IBMX was associated with a decrease in cell proliferation as evidenced by a reduction in numbers of cells incorporating 5-bromo-2-deoxyuridine (BrdU). No increase in process extension was observed following exposure to NGF or retinoic acid. MCD-1 cells were shown to produce transforming growth factor beta (TGF beta), and were immunopositive for mutant p53. Transfection assays with the PG13-Luc reporter plasmid, which contains a p53-responsive enhancer element and a luciferase reporter gene, suggested MCD-1 cells are deficient in wild-type p53 and do not activate p53 on treatment with the anticancer agent adriamycin. The MCD-1 cell line is suggested to represent an abnormally differentiated cell type, which has some properties consistent with a multipotent neuronal phenotype while retaining some properties of immature cells of a glial lineage. The MCD-1 cell line can be used to provide a model of a medulloblastoma cell line that is resistant to growth-controlling and anticancer agents.