Cerebral blood flow regulation and cognitive performance in hypertension.

We examined the relation between transcranial Doppler (TCD) markers of cerebral blood flow regulation and cognitive performance in hypertension (HT) patients to evaluate the predictive value of these markers for cognitive decline. We assessed dynamic cerebral autoregulation (dCA), vasoreactivity to carbon dioxide, and neurovascular coupling (NVC) in the middle (MCA) and posterior (PCA) cerebral arteries of 52 patients. Neuropsychological evaluation included the Montreal Cognitive Assessment and tests covering attention, executive function, processing speed, and memory. Notably, reduced rate time in the PCA significantly predicted better processing speed (p = 0.003). Furthermore, reduced overshoot systolic cerebral blood velocity in the PCA and reduced phase in the VLF range in the MCA (p = 0.021 and p = 0.017, respectively) significantly predicted better memory. Intriguingly, enhanced dCA in the MCA predicted poorer memory performance, while reduced NVC in the PCA predicted both superior processing speed and memory performance. These findings suggest that HT-induced changes in cerebral hemodynamics impact cognitive performance. Further research should verify these observations and elucidate whether these changes represent adaptive responses or neurovascular inefficiency. TCD markers might provide insights into HT-related cognitive decline.

Role of voltage-dependent calcium channels on the striatal in vivo dopamine release induced by the organophosphorus pesticide glyphosate.

In the present study, we investigated the role of voltage-sensitive calcium channels (VSCCs) on the striatal dopamine release induced by the pesticide glyphosate (GLY) using selective VSCC inhibitors. The dopamine levels were measured by in vivo cerebral microdialysis coupled to HPLC-ED. Nicardipine (L-type VSCC antagonist) or ω-conotoxin MVIIC (non-selective P/Q-type antagonist) had no effect on dopamine release induced by 5 mM GLY. In contrast, flunarizine (T-type antagonist) or ω-conotoxin GVIA (neuronal N-type antagonist) significantly reduced GLY-stimulated dopamine release. These results suggest that GLY-induced dopamine release depends on extracellular calcium and its influx through the T- and N-type VSCCs. These findings were corroborated by molecular docking, which allowed us to establish a correlation between the effect of GLY on blocked VSCC with the observed dopamine release. We propose new molecular targets of GLY in the dorsal striatum, which could have important implications for the assessment of pesticide risks in non-target organisms.

Pediatric Kidney Transplantation-Living or Deceased Donor?

BACKGROUND: Kidney transplantation is ideal for children and adolescents with chronic end-stage renal disease because it offers better growth, development, and quality of life. Donor choice is vitally important in this age group, given the long life expectancy of these patients. METHODS: A retrospective analysis of pediatric patients (<18 years) who underwent kidney transplantation from January 1999 to December/2018 was performed. Short- and long-term outcomes were compared between living and deceased donor transplants. RESULTS: We included 59 pediatric kidney transplant recipients, 12 from a living donor and 47 from a deceased donor. Thirty-six (61.0%) patients were boys, and 5 (8.5%) had a retransplant. There were no differences between groups on sex, race, and weight of the recipient and donor, as well as the age and the etiology of the recipient's primary disease. Most recipients received induction immunosuppression with basiliximab and maintenance with triple therapy, with no differences between groups. Living donor transplants were mostly pre-emptive (58.3% vs 4.3%, P < .001) and had fewer HLA mismatches (≤3: 90.9% vs 13.0%, P < .001), older donors (38.4 vs 24.3 years, P < .001) and shorter hospital stays (8.8 vs 14.1 days, P = .004). There were no statistically significant differences regarding medical-surgical complications and graft or patient survival. However, we found that at 13 years post-transplant 91.7% of the living donor grafts were functioning vs 72.3% of the deceased donor grafts. CONCLUSION: Our experience points out that a living donor graft in pediatric patients is associated with a higher probability of pre-emptive transplant, shorter hospital stay, greater HLA compatibility, and increased graft survival.

Neurotoxic effects of exposure to glyphosate in rat striatum: Effects and mechanisms of action on dopaminergic neurotransmission.

The main objective of this study was to evaluate the effects and possible mechanisms of action of glyphosate and a glyphosate-based herbicide (GBH) on dopaminergic neurotransmission in the rat striatum. Acute exposure to glyphosate or GBH, administered by systemic (75 or 150 mg/kg, i.p.) or intrastriatal (1, 5, or 10 mM for 1 h) routes, produced significant concentration-dependent increases in dopamine release measured in vivo by cerebral microdialysis coupled to HPLC with electrochemical detection. Systemic administration of glyphosate also significantly impaired motor control and decreased striatal acetylcholinesterase activity and antioxidant capacity. At least two mechanisms can be proposed to explain the glyphosate-induced increases in extracellular dopamine levels: increased exocytotic dopamine release from synaptic vesicles or inhibition of dopamine transporter (DAT). Thus, we investigated the effects of intrastriatal administration of glyphosate (5 mM) in animals pretreated with tetrodotoxin (TTX) or reserpine. It was observed that TTX (10 or 20 µM) had no significant effect on glyphosate-induced dopamine release, while reserpine (10 mg/kg i.p) partially but significantly reduced the dopamine release. When glyphosate was coinfused with nomifensine (50 µM), the increase in dopamine levels was significantly higher than that observed with glyphosate or nomifensine alone. So, two possible hypotheses could explain this additive effect: both glyphosate and nomifensine act through different mechanisms at the dopaminergic terminals to increase dopamine levels; or both nomifensine and glyphosate act on DAT, with glyphosate simultaneously inhibiting reuptake and stimulating dopamine release by reversing the DAT function. Future research is needed to determine the effects of this pesticide at environmentally relevant doses.

An annotated checklist and distribution of earthworms from Venezuela (Megadrili: Crassiclitellata).

An earthworm checklist has produced 78 nominal taxa (species/subspecies) of earthworm reported to date in Venezuela. The list of nominal taxa was obtained through literature review and the distribution maps were plotted by ecoregion. The 78 species/subspecies are divided into 24 genera and 6 families. Native earthworm species were more widely distributed than peregrine and exotic and are more associated with the conserved areas. Exotic species had been collected mainly in the north of the country in areas with at least some disturbance history. The peregrine species P. corethrurus is also widely distributed but with a preference for disturbed areas or related to its native natural grassland condition near the Guayana's shield. This is the first accurate assessment of Venezuela's earthworm species and subspecies in the last 14 years.

Additions to earthworms (Annelida, Crassiclitellata) from Aragua and Miranda states, Venezuela.

Two new species of the earthworm genus Pontoscolex found in San Casimiro County, northern Venezuela are described. Because of some morphological variability, and to improve the previous description, we redescribe Onychochaeta windlei and Rhinodrilus fuenzalidae collected at La Cortada settlement, Miranda state. Pontoscolex (Mesoscolex) juanae sp. n. and Pontoscolex (Nulloscolex) hugoi subgen. n., sp. n have three pairs of tiny calciferous glands in 7th to 9th segments, with a simple tubular structure similar to that of the genus Onychochaeta; however, testes and funnels are enclosed in sacs in the 11th segment similar to the Pontoscolex. We also report the occurrences of Pontoscolex (Pontoscolex) corethrurus Müller, 1857, Metaphire houlleti (Perrier, 1872), Perionyx excavatus Perrier, 1872, Dichogaster bolaui (Michaelsen, 1891), and Eisenia fetida (Savigny, 1826).

Role of voltage-sensitive Ca2+ channels in the in vivo dopamine release induced by the organophosphorus pesticide glufosinate ammonium in rat striatum.

The possible role of voltage-sensitive calcium channels (VSCC) activation in the glufosinate ammonium (GLA)-induced dopamine release was investigated using selective VSCC blockers and the dopamine levels were measured by HPLC from samples obtained by in vivo cerebral microdialysis. While pretreatment with 10 µM flunarizine (T-type VSCC antagonist) or nicardipine (L-type VSCC antagonist) had no statistically significant effect on dopamine release induced by 10 mM GLA, pretreatment with 100 µM of both antagonists, or 20 µM ω-conotoxin MVIIC (non-selective P/Q-type VSCC antagonist) significantly decreased the GLA-induced dopamine release over 72.2%, 73%, and 70.2%, respectively. Administration of the specific antagonist of neuronal N-type VSCCs, the ω-conotoxin GVIA (20 µM), produced an almost complete blockade of in vivo dopamine release induced by GLA. These results show that GLA-induced dopamine release could be produced by the activation of a wide range of striatal VSCC located at the synaptic terminals and axons of striatal dopaminergic neurons, especially N-type VSCC.

Could salt intake directly affect the cerebral microvasculature in hypertension?

OBJECTIVES: Excess dietary salt and chronic kidney disease (CKD) are acknowledged stroke risk factors. The development of small vessel disease, similarly affecting the cerebral and renal microvasculatures, may be an important mechanistic link underlying this interaction. Therefore, we aimed to evaluate if the dietary salt intake and markers of CKD (estimated glomerular filtration rate, albuminuria) relate to transcranial Doppler (TCD) markers of cerebral small vessel disease (CSVD) in hypertensive patients. MATERIALS AND METHODS: Fifty-six hypertensive patients (57% with diabetes) underwent TCD monitoring in the middle (MCA) and posterior (PCA) cerebral arteries for evaluating neurovascular coupling (NVC), dynamic cerebral autoregulation (dCA), and vasoreactivity to carbon dioxide (VRCO2). We investigated the relation between renal parameters and TCD studies using Pearson's correlation coefficient and linear regression analyses. RESULTS: There were no associations between dCA, VRCO2, NVC, and renal function tests. However, there was a negative association between the daily salt intake and the natural frequency during visual stimulation (r2=0.101, ß=-0.340, p=0.035), indicative of increased rigidity of the cerebral resistance vessels that react to cognitive activation. CONCLUSIONS: In this cross-sectional study, we found an association between excess dietary salt consumption and CSVD in hypertensive patients. Future research is needed to evaluate whether the natural frequency could be an early, non-invasive, surrogate marker for microvascular dysfunction in hypertension.

Toxic Effects of Glyphosate on the Nervous System: A Systematic Review.

Glyphosate, a non-selective systemic biocide with broad-spectrum activity, is the most widely used herbicide in the world. It can persist in the environment for days or months, and its intensive and large-scale use can constitute a major environmental and health problem. In this systematic review, we investigate the current state of our knowledge related to the effects of this pesticide on the nervous system of various animal species and humans. The information provided indicates that exposure to glyphosate or its commercial formulations induces several neurotoxic effects. It has been shown that exposure to this pesticide during the early stages of life can seriously affect normal cell development by deregulating some of the signaling pathways involved in this process, leading to alterations in differentiation, neuronal growth, and myelination. Glyphosate also seems to exert a significant toxic effect on neurotransmission and to induce oxidative stress, neuroinflammation and mitochondrial dysfunction, processes that lead to neuronal death due to autophagy, necrosis, or apoptosis, as well as the appearance of behavioral and motor disorders. The doses of glyphosate that produce these neurotoxic effects vary widely but are lower than the limits set by regulatory agencies. Although there are important discrepancies between the analyzed findings, it is unequivocal that exposure to glyphosate produces important alterations in the structure and function of the nervous system of humans, rodents, fish, and invertebrates.

Systematic Review of Calcium Channels and Intracellular Calcium Signaling: Relevance to Pesticide Neurotoxicity.

Pesticides of different chemical classes exert their toxic effects on the nervous system by acting on the different regulatory mechanisms of calcium (Ca2+) homeostasis. Pesticides have been shown to alter Ca2+ homeostasis, mainly by increasing its intracellular concentration above physiological levels. The pesticide-induced Ca2+ overload occurs through two main mechanisms: the entry of Ca2+ from the extracellular medium through the different types of Ca2+ channels present in the plasma membrane or its release into the cytoplasm from intracellular stocks, mainly from the endoplasmic reticulum. It has also been observed that intracellular increases in the Ca2+ concentrations are maintained over time, because pesticides inhibit the enzymes involved in reducing its levels. Thus, the alteration of Ca2+ levels can lead to the activation of various signaling pathways that generate oxidative stress, neuroinflammation and, finally, neuronal death. In this review, we also discuss some proposed strategies to counteract the detrimental effects of pesticides on Ca2+ homeostasis.

Neurovascular Coupling Is Impaired in Hypertensive and Diabetic Subjects Without Symptomatic Cerebrovascular Disease.

The mechanistic link between hypertension, diabetes and cerebral small vessel disease (CSVD) is still poorly understood. We hypothesized that hypertension and diabetes could impair cerebrovascular regulation prior to irreversibly established cerebrovascular disease. In this study, 52 hypertensive patients [54% males; age 64 ± 11 years; 58% with comorbid diabetes mellitus (DM)] without symptomatic cerebrovascular disease underwent transcranial Doppler (TCD) monitoring in the middle (MCA) and posterior (PCA) cerebral arteries, to assess vasoreactivity to carbon dioxide (VRCO2) and neurovascular coupling (NVC). 1.5T magnetic resonance imaging was also performed and white matter hyperintensity volume was automatically segmented from FLAIR sequences. TCD data from 17 healthy controls were obtained for comparison (47% males; age 60 ± 16 years). Hypertensive patients showed significant impairment of NVC in the PCA, with reduced increment in cerebral blood flow velocity during visual stimulation (22.4 ± 9.2 vs. 31.6 ± 5.7, p < 0.001), as well as disturbed NVC time-varying properties, with slower response (lower rate time: 0.00 ± 0.02 vs. 0.03 ± 6.81, p = 0.001), and reduced system oscillation (reduced natural frequency: 0.18 ± 0.08 vs. 0.22 ± 0.06, p < 0.001), when compared to controls. VRCO2 remained relatively preserved in MCA and PCA. These results were worse in hypertensive diabetic patients, with lower natural frequency (p = 0.043) than non-diabetic patients. White matter disease burden did not predict worse NVC. These findings suggest that hypertensive diabetic patients may have a precocious impairment of NVC, already occurring without symptomatic CSVD. Future research is warranted to evaluate whether NVC assessment could be useful as an early, non-invasive, surrogate marker for CSVD.

Neurotoxic Effects of Neonicotinoids on Mammals: What Is There beyond the Activation of Nicotinic Acetylcholine Receptors?-A Systematic Review.

Neonicotinoids are a class of insecticides that exert their effect through a specific action on neuronal nicotinic acetylcholine receptors (nAChRs). The success of these insecticides is due to this mechanism of action, since they act as potent agonists of insect nAChRs, presenting low affinity for vertebrate nAChRs, which reduces potential toxic risk and increases safety for non-target species. However, although neonicotinoids are considered safe, their presence in the environment could increase the risk of exposure and toxicity. On the other hand, although neonicotinoids have low affinity for mammalian nAChRs, the large quantity, variety, and ubiquity of these receptors, combined with its diversity of functions, raises the question of what effects these insecticides can produce in non-target species. In the present systematic review, we investigate the available evidence on the biochemical and behavioral effects of neonicotinoids on the mammalian nervous system. In general, exposure to neonicotinoids at an early age alters the correct neuronal development, with decreases in neurogenesis and alterations in migration, and induces neuroinflammation. In adulthood, neonicotinoids induce neurobehavioral toxicity, these effects being associated with their modulating action on nAChRs, with consequent neurochemical alterations. These alterations include decreased expression of nAChRs, modifications in acetylcholinesterase activity, and significant changes in the function of the nigrostriatal dopaminergic system. All these effects can lead to the activation of a series of intracellular signaling pathways that generate oxidative stress, neuroinflammation and, finally, neuronal death. Neonicotinoid-induced changes in nAChR function could be responsible for most of the effects observed in the different studies.

Cetoacidosis diabética euglucémica, un diagnóstico difícil de identificar / Euglicemic diabetic ketoacidosis, an easily missed diagnosis

Diabetic ketoacidosis is a serious and potentially life-threatening acute complication of diabetes mellitus. SGLT-2 inhibitors are recommended as first-line therapy in patients unable to tolerate metformin or as second-line agents after metformin. Their use is increasing as new data show, besides improving glycemic control, weight loss, blood pressure reduction, and beneficial cardiovascular and reno-protective effects. Euglycemic diabetic ketoacidosis is a rare but potential complication of SGLT-2 inhibitors. Physicians including internists, intensivists and emergency physicians should all be aware as this diagnosis can easily be missed in the absence of evident hyperglycemia. We report a case of 61-year-old male admitted in the emergency room because of altered mental status, associated with holocranial headache. He had medical history of type 2 diabetes and had recently started a SLGT-2 inhibitor. Arterial blood gases showed a severe high anion gap uncompensated metabolic acidosis. Blood and urine ketones were high with normal serum glucose levels. The diagnosis of euglycemic ketoacidosis due to SLGT-2 inhibitor was made. (AU)

Função endotelial e perfil lipídico de pessoas com esquizofrenia participantes de um programa de emprego apoiado / Endothelial function and lipid profile of individuals with schizophrenia participating in a supported employment program

Introdução: Pessoas com esquizofrenia habitualmente têm um funcionamento social empobrecido e são sedentárias. A participação social, especialmente a inclusão no universo do trabalho, pode interferir positivamente na vida dessas pessoas, reduzindo o sedentarismo e melhorando sua saúde. Objetivo: Avaliar o perfil lipídico e os marcadores da função endotelial de pessoas com esquizofrenia participantes de um programa de emprego apoiado. Método: Pesquisa quantitativa do tipo quase-experimental que avaliou um grupo de 14 sujeitos com esquizofrenia participantes de um programa de inclusão laboral. Os sujeitos foram avaliados antes de ingressarem no programa (momento 1) e um ano depois (momento 2). Foram dosados: colesterol total e frações, triglicerídeos, nitritos e nitratos séricos (marcadores da função endotelial). Os dados foram analisados com o auxílio do software SPSS 20. Resultados: As frações de colesterol high density lipoprotein (HDL-C) e low density lipoprotein (LDL-C) sofreram modificações significativas após o período de um ano de inserção no mercado de trabalho. O HDL aumentou de 82,30 para 98,60 mg/dL (p<0,01). Já o LDL apresentou uma redução de 54,50 para 44,45 mg/dL (p<0,02). Os triglicerídeos e o colesterol total mantiveram-se estáveis. Com relação aos nitritos e nitratos, houve diminuição significativa de 15,20 para 14,48 µmol (p<0,01). Discussão: A participação no programa de emprego apoiado pode ter influenciado positivamente no perfil lipídico dos sujeitos e em sua função endotelial. Além disso, os nitritos também têm sido apontados como mediadores do processo inflamatório neural e sua diminuição está associada à melhora no prognóstico de doenças crônicas como a esquizofrenia

Background: The social function of individuals with schizophrenia is usually poor and this population exhibits a sedentary lifestyle. Social participation, inclusion in the world of work in particular, might favorably interfere with the lives of these individuals by reducing sedentarism and improving their state of health. Objective: To analyze the lipid profile and endothelial function markers among individuals with schizophrenia enrolled in a supported employment program. Methods: Quantitative quasi-experimental study conducted with 14 individuals with schizophrenia enrolled in a labor inclusion program. Participants were assessed before enrolment (time-point 1) and one year later (time-point 2). Total cholesterol and fractions, triglycerides, serum nitrates and nitrites (endothelial function markers) were measured. The data were analyzed with software SPSS 20. Results: The high-density lipoprotein (HDL) and low-density lipoprotein (LDL) levels exhibited significant changes one year after inclusion in the labor market. HDL increased from 82.30 to 98.60 mg/dL (p<0.01) and LDL decreased from 54.50 to 44.45 mg/dL (p<0.02). The triglyceride and total cholesterol levels remained stable. The nitrate and nitrite level exhibited significant reduction from 15.20 to 14.48 µMol (p<0.01). Conclusion: Participation in the supported employment program might have favorably influenced the participants' lipid profile and endothelial function. Nitrites have been described as mediators in the neural inflammatory process, and reduction of their levels is associated with better prognosis of chronic diseases such as schizophrenia.

Malformaciones congénitas pulmonares diagnosticadas en un periodo de 10 años / Congenital Pulmonary Malformations Diagnosed Over a Period of 10 Years

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Endothelial function and lipid profile of individuals with schizophrenia participating in a supported employment program.

BACKGROUND: The social function of individuals with schizophrenia is usually poor and this population exhibits a sedentary lifestyle. Social participation, inclusion in the world of work in particular, might favorably interfere with the lives of these individuals by reducing sedentarism and improving their state of health. OBJECTIVE: To analyze the lipid profile and endothelial function markers among individuals with schizophrenia enrolled in a supported employment program. METHODS: Quantitative quasi-experimental study conducted with 14 individuals with schizophrenia enrolled in a labor inclusion program. Participants were assessed before enrolment (time-point 1) and one year later (time-point 2). Total cholesterol and fractions, triglycerides, serum nitrates and nitrites (endothelial function markers) were measured. The data were analyzed with software SPSS 20. RESULTS: The high-density lipoprotein (HDL) and low-density lipoprotein (LDL) levels exhibited significant changes one year after inclusion in the labor market. HDL increased from 82.30 to 98.60 mg/dL (p<0.01) and LDL decreased from 54.50 to 44.45 mg/dL (p<0.02). The triglyceride and total cholesterol levels remained stable. The nitrate and nitrite level exhibited significant reduction from 15.20 to 14.48 µMol (p<0.01). CONCLUSION: Participation in the supported employment program might have favorably influenced the participants' lipid profile and endothelial function. Nitrites have been described as mediators in the neural inflammatory process, and reduction of their levels is associated with better prognosis of chronic diseases such as schizophrenia.

INTRODUÇÃO: Pessoas com esquizofrenia habitualmente têm um funcionamento social empobrecido e são sedentárias. A participação social, especialmente a inclusão no universo do trabalho, pode interferir positivamente na vida dessas pessoas, reduzindo o sedentarismo e melhorando sua saúde. OBJETIVO: Avaliar o perfil lipídico e os marcadores da função endotelial de pessoas com esquizofrenia participantes de um programa de emprego apoiado. MÉTODO: Pesquisa quantitativa do tipo quase-experimental que avaliou um grupo de 14 sujeitos com esquizofrenia participantes de um programa de inclusão laboral. Os sujeitos foram avaliados antes de ingressarem no programa (momento 1) e um ano depois (momento 2). Foram dosados: colesterol total e frações, triglicerídeos, nitritos e nitratos séricos (marcadores da função endotelial). Os dados foram analisados com o auxílio do software SPSS 20. RESULTADOS: As frações de colesterol high density lipoprotein (HDL-C) e low density lipoprotein (LDL-C) sofreram modificações significativas após o período de um ano de inserção no mercado de trabalho. O HDL aumentou de 82,30 para 98,60 mg/dL (p<0,01). Já o LDL apresentou uma redução de 54,50 para 44,45 mg/dL (p<0,02). Os triglicerídeos e o colesterol total mantiveram-se estáveis. Com relação aos nitritos e nitratos, houve diminuição significativa de 15,20 para 14,48 µmol (p<0,01). DISCUSSÃO: A participação no programa de emprego apoiado pode ter influenciado positivamente no perfil lipídico dos sujeitos e em sua função endotelial. Além disso, os nitritos também têm sido apontados como mediadores do processo inflamatório neural e sua diminuição está associada à melhora no prognóstico de doenças crônicas como a esquizofrenia.

Phosphoproteome analysis reveals a critical role for hedgehog signalling in osteoblast morphological transitions.

The reciprocal and adaptive interactions between cells and substrates governing morphological transitions in the osteoblast compartment remain largely obscure. Here we show that osteoblast cultured in basement membrane matrix (Matrigel™) exhibits significant morphological changes after ten days of culture, and we decided to exploit this situation to investigate the molecular mechanisms responsible for guiding osteoblast morphological transitions. As almost all aspects of cellular physiology are under control of kinases, we generated more or less comprehensive cellular kinome profiles employing PepChip peptide arrays that contain over 1000 consensus substrates of kinase peptide. The results obtained were used to construct interactomes, and these revealed an important role for FoxO in mediating morphological changes of osteoblast, which was validated by Western blot technology when FoxO was significantly up-expressed in response to Matrigel™. As FoxO is a critical protein in canonical hedgehog signalling, we decided to explore the possible involvement of hedgehog signalling during osteoblast morphological changes. It appeared that osteoblast culture in Matrigel™ stimulates release of a substantial amounts Shh while concomitantly inducing upregulation of the expression of the bona fide hedgehog target genes Gli-1 and Patched. Functional confirmation of the relevance of these results for osteoblast morphological transitions came from experiments in which Shh hedgehog signalling was inhibited using the well-established pathway inhibitor cyclopamine (Cyc). In the presence of Cyc, culture of osteoblasts in Matrigel™ is not capable of inducing morphological changes but appears to provoke a proliferative response as evident from the upregulation of Cyclin D3 and cdk4. The most straightforward interpretation of our results is that hedgehog signalling is both necessary and sufficient for membrane matrix-based morphological transitions.

Characteristics of sulfasalazine-induced cytotoxicity in C6 rat glioma cells.

Glioblastoma is the most aggressive primary brain tumor. Surgical resection, radiotherapy and temozolomide (TMZ), an alkylating agent, is the standard of care. Glioma cells may synthetize the antioxidant glutathione by importing cystine through a cystine/glutamate antiporter, which is inhibited by sulfasalazine (SAS). C6 rat glioma cells are largely used in in vitro and in vivo models for developing new glioblastoma treatment strategies. We treated C6 cells with 25µM TMZ and/or 0.25mM or 0.5mM SAS for 1, 3 or 5days and evaluated viability, apoptosis, total glutathione levels and metalloproteinase MMP2 and MMP9 activities. TMZ treatment slightly reduced cell viability by 9.5% compared with vehicle treatment (0.1% dimethyl sulfoxide) only after 5days. In addition, TMZ did not modify apoptosis, glutathione content or MMP2/MMP9 activities. The 0.25mM SAS treatment reduced cell viability by 31.1% and 19.4% after the first and third days, respectively. This effect was not sustained after the fifth day of treatment. In contrast, 0.5mM SAS caused a reduction in cell viability by nearly 100%, total glutathione depletion and apoptosis induction. Moreover, the effect of 0.5mM SAS was greater than that of TMZ in terms of cell viability reduction, total glutathione depletion and apoptosis induction. MMP9 activity was reduced by 40% after 5days of 25µM TMZ and 0.5mM SAS co-administration. Considering previous data from our group, we verified that the cellular viability results differed between rat and human cells; C6 cells were more vulnerable to 0.5mM SAS than human A172 and T98G glioblastoma lineages. We propose that C6 cells may not be appropriate for studying human glioblastoma and that the results obtained using these cells should be interpreted with caution.