Kynurenine Monooxygenase Expression and Activity in Human Astrocytomas.

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor. The enzyme indoleamine-2,3-dioxygenase (IDO), which participates in the rate-limiting step of tryptophan catabolism through the kynurenine pathway (KP), is associated with poor prognosis in patients with GBM. The metabolites produced after tryptophan oxidation have immunomodulatory properties that can support the immunosuppressor environment. In this study, mRNA expression, protein expression, and activity of the enzyme kynurenine monooxygenase (KMO) were analyzed in GBM cell lines (A172, LN-18, U87, U373) and patient-derived astrocytoma samples. KMO mRNA expression was assessed by real-time RT-qPCR, KMO protein expression was evaluated by flow cytometry and immunofluorescence, and KMO activity was determined by quantifying 3-hydroxykynurenine by HPLC. Heterogenous patterns of both KMO expression and activity were observed among the GBM cell lines, with the A172 cell line showing the highest KMO expression and activity. Higher KMO mRNA expression was observed in glioma samples than in patients diagnosed with only a neurological disease; high KMO mRNA expression was also observed when using samples from patients with GBM in the TCGA program. The KMO protein expression was localized in GFAP+ cells in tumor tissue. These results suggest that KMO is a relevant target to be explored in glioma since it might play a role in supporting tumor metabolism and immune suppression.

Early expression of the receptor for advanced glycation end products in a toxic model produced by 6-hydroxydopamine in the rat striatum.

The receptor for advanced glycation end products (RAGE) is commonly involved in different neurodegenerative and inflammatory disorders. The cellular signaling associated to RAGE activation may occur upon binding to different ligands. In this study we investigated whether the toxic model produced by 6-hydroxydopamine (6-OHDA) in rats comprises early noxious responses related to RAGE-mediated signaling cascades. In order to explore a possible interaction between 6-OHDA and RAGE, affinity parameters of RAGE with 6-OHDA were estimated by different means. The possible binding sites of 6-OHDA with the VC1 homodimer for both rat and human RAGE were also modeled. Our results show that the striatal infusion of 6-OHDA recruits RAGE upregulation, as evidenced by an early expression of the receptor. 6-OHDA was also found to bind the VC1 homodimer, although its affinity was moderate when compared to other ligands. This work contributes to the understanding of the role of RAGE activation for 6-OHDA-induced neurotoxicity.

Biotin deprivation impairs mitochondrial structure and function and has implications for inherited metabolic disorders.

Certain inborn errors of metabolism result from deficiencies in biotin containing enzymes. These disorders are mimicked by dietary absence or insufficiency of biotin, ATP deficit being a major effect,whose responsible mechanisms have not been thoroughly studied. Here we show that in rats and cultured cells it is the result of reduced TCA cycle flow, partly due to deficient anaplerotic biotin-dependent pyruvate carboxylase. This is accompanied by diminished flow through the electron transport chain, augmented by deficient cytochrome c oxidase (complex IV) activity with decreased cytochromes and reduced oxidative phosphorylation. There was also severe mitochondrial damage accompanied by decrease of mitochondria, associated with toxic levels of propionyl CoA as shown by carnitine supplementation studies, which explains the apparently paradoxical mitochondrial diminution in the face of the energy sensor AMPK activation, known to induce mitochondria biogenesis. This idea was supported by experiments on AMPK knockout mouse embryonic fibroblasts (MEFs). The multifactorial ATP deficit also provides a plausible basis for the cardiomyopathy in patients with propionic acidemia, and other diseases.Additionally, systemic inflammation concomitant to the toxic state might explain our findings of enhanced IL-6, STAT3 and HIF-1α, associated with an increase of mitophagic BNIP3 and PINK proteins, which may further increase mitophagy. Together our results imply core mechanisms of energy deficit in several inherited metabolic disorders.

Modeling the interaction between quinolinate and the receptor for advanced glycation end products (RAGE): relevance for early neuropathological processes.

The receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor involved in neurodegenerative and inflammatory disorders. RAGE induces cellular signaling upon binding to a variety of ligands. Evidence suggests that RAGE up-regulation is involved in quinolinate (QUIN)-induced toxicity. We investigated the QUIN-induced toxic events associated with early noxious responses, which might be linked to signaling cascades leading to cell death. The extent of early cellular damage caused by this receptor in the rat striatum was characterized by image processing methods. To document the direct interaction between QUIN and RAGE, we determined the binding constant (Kb) of RAGE (VC1 domain) with QUIN through a fluorescence assay. We modeled possible binding sites of QUIN to the VC1 domain for both rat and human RAGE. QUIN was found to bind at multiple sites to the VC1 dimer, each leading to particular mechanistic scenarios for the signaling evoked by QUIN binding, some of which directly alter RAGE oligomerization. This work contributes to the understanding of the phenomenon of RAGE-QUIN recognition, leading to the modulation of RAGE function.

Dose-dependent antihypertensive determination and toxicological studies of tilianin isolated from Agastache mexicana.

ETHNOPHARMACOLOGICAL RELEVANCE: Agastache mexicana is used in Mexican traditional medicine for the treatment of hypertension, anxiety and related diseases. AIM OF THE STUDY: Current work was developed to establish pharmacological/toxicological parameters of tilianin, a flavone extracted from Agastache mexicana in order to propose it for clinical trials. MATERIALS AND METHODS: Acute and sub-acute toxicology studies in Imprinting Control Region (ICR) mice and median effective dose (ED50) determination in conscious spontaneously hypertensive rats (SHR) were done. RESULTS: A median lethal dose (LD50) of 6624 mg/kg (6201, 7076) in mice and significant antihypertensive effect (ED50=53.51 mg/kg) in SHR were determined. Moreover, sub-acute oral administration of tilianin did not alter body weight, clinical chemistry parameters (alanine amino-transferase, aspartate amino-transferase, total cholesterol, high density lipoprotein, low density lipoprotein, triglycerides, glucose and insulin), and also did not induce any toxic or adverse effects on kidney, heart, liver, and lung functions. CONCLUSIONS: We have shown that tilianin, isolated from Agastache mexicana, was not toxic for rodents. Also, its antihypertensive effect was dose-dependent and ED50 (53.51 mg/kg) calculated was lesser than LD50 determined (6624 mg/kg), which suggest a wide range of pharmacology-toxicology patterns. Results support the hypothesis that tilianin must be investigated and developed for clinical trials as antihypertensive drug.

Specific bacterial genotypes of Mycobacterium tuberculosis cause extensive dissemination and brain infection in an experimental model.

Meningeal tuberculosis is a severe type of extrapulmonary disease, which is thought to begin with respiratory infection, followed by hematogenous dissemination and brain infection. Host genetic susceptibility factors and specific mycobacterial substrains could be involved in its development. From an epidemiological study in Colombia, we selected three Mycobacterium tuberculosis clinical strains isolated from the cerebrospinal fluid (CSF) of patients with meningeal tuberculosis, and used them to infect BALB/c mice through the intratracheal route. These strains showed a distinctive spoligotype pattern. The course of infection in terms of strain virulence (mice survival, bacillary loads in lungs), bacilli dissemination and extrapulmonary infection (bacilli loads in blood, brain, liver, kidney and spleen), and immune responses (cytokine expression determined by real time PCR in brain and lung) was studied and compared with that induced by the laboratory strain H37Rv and other five clinical strains isolated from patients with pulmonary TB. All the clinical isolates from meningeal TB patients disseminated extensively through the hematogenous route infecting the brain, producing inflammation in the cerebral parenchyma and meninges, whereas H37Rv and clinical isolates from pulmonary TB patients showed very limited efficiency to infect the brain. Thus, it seems that mycobacterial strains with a distinctive genotype are able to disseminate extensively after the respiratory infection and infect the brain.

Angiogenesis and expression of estrogen and progesterone receptors as predictive factors for recurrence of meningioma.

Meningiomas are benign tumors, with low rate of recurrence after surgery. The most important factor predicting recurrence is the extent of surgical resection; other factors have been studied with conflicting results. Angiogenesis, an important substratum for growth and spread of neoplasic cells, and the expression of estrogen and progesterone receptors (ER, PR), could play a role in the recurrence of meningioma. We evaluated 42 patients with meningioma diagnosis (confirmed by histopathology) treated exclusively by surgery between January 1995 and December 1999, and compared the recurring and non-recurring groups after a ten-year follow-up period. Recurrence was associated with several factors including vascular density (VD), cell proliferation index (CPI), ER, PR, and cyclin E (CE) tissue expression, as evaluated by immunohistochemistry. Complete surgical resection was achieved in 41% of patients. Recurrence of meningioma was found in 17 patients (40%). Median + or - standard deviation (SD) of recurrence time was 32 + or - 5 months. When recurrence versus no recurrence was compared, mean + or - SD of VD and CPI were 9 + or - 3.6 and 607.6 + or - 233 (40x/10 fields) respectively. Tissue expression was positive for ER, PR, and CE in 28, 62 and 91% of patients, respectively. The sole significant recurrence-associated factors were extent of resection (P = 0.003) and VD (P = 0.004). ER, PR, and CE-tissue expression were not statistically significant. The most important factor associated with meningioma relapse was vascular density, independently of hormonal status and extent of surgical resection. Patients with a high risk of recurrence could benefit from additional treatment.

[Clinical pathological study of craniopharyngioma. Fifteen years at the National Institute of Neurology and Neurosurgery "Manuel Velasco Suárez"]. / Craneofaringioma, estudio clínico-patológico. Quince años del Instituto Nacional de Neurología y Neurocirugía "Manuel Velasco Suárez".

BACKGROUND: Craniopharyngioma is a sellar region benign cyst It's frequency ranges from 1.2% to 4.6% of all brain tumors. OBJECTIVE: To carry out a clinical pathological correlation of craniopharyngioma among adults and describe the tumor's biological characteristics. METHODS: We included 115 craniopharyngiomas; 100 were adamantimomatous and 15 were papillary type. Patient's age range was 15-90 years (mean 52.5 yrs); 54 (47%) were males and 61 (53%) females. The most frequent location was the supraselar region in 49 (42.6%) of cases. Total exeresis was performed in 72 patients (62.6%) and partial exeresis in 43 (37.4%). RESULTS: We noted a recurrence among 50 patients (43%), of which 5/15 were papillary and 45/100 adamantinomatous. The mean patient age for recurrent tumors was 50.46+/-14.13yrs and 48.65+/-11.95 for non recurrent tumors. Thirteen patients died (11.3%). We observed a statistical correlation between recurrence, exeresis (p=0.014), and death (p=0.047). Follow-up was longer among females than males and in suprasellar tumor location, papillary type, external epithelium cysts and laxo stellate reticulum. CONCLUSIONS: However a good prognostic factor in craniopharyngiomas was observed in older female patients with complete exeresis, small tumors, external epithelium cysts, edematous stroma, inflammation, and absence of atypical cell and mitosis.

[Physiopathology of prion diseases]. / Fisiopatología de las enfermedades por priones.

Prion diseases are a group of degenerative disorders characterized by being progressive, fast growing, and fatal, they affect humans and animals. Due to their physiopathogeny, these disorders can be sporadic, genetic, or infectious. Prions are cellular proteins that lack nucleic acids; they are not viruses or microorganisms. Prions induce neuronal death, brain spongiosis, which are a hallmark of these diseases, as well as amyloid prion protein plaque aggregates. Although the causes that favor pathogenic prion proteins remain uncertain, it is possible that conformational changes of the prion protein allow them to create copies of themselves to form aggregates and induce neuronal death. Other theories suggest that quantitative and qualitative changes in the glycosylation pattern induce the pathological prion form. The latter allows to explain some of their interactions and to understand better the conformational changes and the physico-chemical properties of the prion protein. We review some of the first biological functions (as a transporter of Cu2+ ions) that have been described to this molecule. The present review focuses on different aspects of prion diseases aimed at understanding better their physiopathogenic characteristics.

Fisiopatología de las enfermedades por priones / Physiopathology of prion diseases

Las enfermedades por priones, son trastornos neurodegenerativos progresivos rápidos e invariablemente fatales que afectan tanto a seres humanos como a animales. Tienen formas de presentación esporádica, genética e infecciosa. Los priones son proteínas celulares. No contienen ácidos nucleicos y no son virus o microorganismos. En todos los casos, provocan muerte neuronal, espongiosis común del cerebro, que caracteriza a estas enfermedades, así como agregación de la proteína amiloide prión en forma de placa. La teoría más importante hasta el momento, es la que trata de explicar el cambio de conformación de la proteína prión para producir copias de sí misma y para su agregación y la muerte de las neuronas. Sin embargo, nuevas formas de explicación toman auge actualmente. Una de las más importantes se basa en entender el contenido y cambio de la glicosilación de la proteína prión patológica. Esto permite explicar algunas de sus interacciones, para entender el cambio de conformación y las propiedades físico-químicas de la proteína. Así como algunas de las primeras funciones biológicas (como transportador de iones Cu++2) descritas para esta molécula. En esta revisión abordamos todos los tópicos importantes acerca de estas patologías por demás fascinantes.

Prion diseases are a group of degenerative disorders characterized by being progressive, fast growing, and fatal, they affect humans and animals. Due to their physiopathogeny, these disorders can be sporadic, genetic, or infectious. Prions are cellular proteins that lack nucleic acids; they are not viruses or microorganisms. Prions induce neuronal death, brain spongiosis, which are a hallmark of these diseases, as well as amyloid prion protein plaque aggregates. Although the causes that favor pathogenic prion proteins remain uncertain, it is possible that conformational changes of the prion protein allow them to create copies of themselves to form aggregates and induce neuronal death. Other theories suggest that quantitative and qualitative changes in the glycosylation pattern induce the pathological prion form. The latter allows to explain some of their interactions and to understand better the conformational changes and the physico-chemical properties of the prion protein. We review some of the first biological functions (as a transporter of Cu2+ ions) that have been described to this molecule. The present review focuses on different aspects of prion diseases aimed at understanding better their physiopathogenic characteristics.

EGP-314 is expressed differentially in three brain zones at an early time in an experimentally induced ischemia rat model.

Gene expression in frontal, occipital, and hippocampal regions of rat brains at 15 min of ischemic injury was studied in a rat model by producing focal cerebral ischemia through middle cerebral artery (MCA) occlusion without reperfusion. Catalase, epithelial glycoprotein (EGP-314), cytochrome C oxidase-subunit 1, ribosomal L31 protein, and ceruloplasmin were found to be differentially expressed. Specific primers were designed to study this newly reported brain EGP-314, a cellular adhesion molecule involved in cell-cell and cell-extracellular matrix interactions and related with cytoskeletal organization, differentiation, and proliferation. In the frontal and occipital lobes, EGP-314 expression was low in control and ischemic conditions and increased in sham injured conditions, whereas in the hippocampal region its expression was induced only by ischemia. In situ hybridization and immunohistochemistry revealed that EGP-314 mRNA and the protein were present in the ischemic hippocampus pyramidal neurons. DNA fragmentation was demonstrated by TUNEL and LM-PCR analysis in hippocampus region. TUNEL positive pyramidal neurons were observed at 15 min of ischemia. DNA ladder was found at 12 and 15 min of ischemia.

Coexpression of hepatocyte growth factor/scatter factor (HGF/SF) and its receptor cMET predict recurrence of meningiomas.

Hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, the cMET tyrosine kinase participate in cancer invasion, angiogenesis and metastasis in a wide variety of neoplastic cells. Meningioma is a bening tumour, however, it has a high rate of recurrence after surgery; the most important factor to predict relapse is the extent of surgical resection, several other potentially predictive factors have been studied with poor results. We examined by immunohistochemistry the expression of HGF/SF and its cMET receptor in a group of patients with benign meningioma with or without recurrence (n = 17 and n = 25, respectively), after a minimal follow-up of least 6 years. Expression and coexpression of HGF/SF and cMET were compared with cell proliferation index, vascular density and clinical outcome. Coexpression of HGF/SF and cMET in meningiomas had a significant association with cell proliferation index and with recurrence (P < 0.037). Determination of HGF and cMET coexpression in meningiomas could be used as a predictor of recurrence.

Taenia crassiceps cysticercosis in mice does not increase the carcinogenic effect of methyl-nitrosourea.

An association between brain cysticercosis and malignant neoplasms in humans has recently been reported. To explore the possibility of a potentiating effect of cysticercosis on carcinogenesis mice infected with Taenia crassiceps cysticerci were exposed to the carcinogenic substance methyl-nitrosourea; 35% of them developed lymphoma, in contrast with 50% of control non-infected animals exposed to MNU. In this experimental model of cysticercosis we did not find a potentiating effect of peritoneal cysticercosis on the carcinogenicity of MNU.

Hepatocyte growth factor is associated with poor prognosis of malignant gliomas and is a predictor for recurrence of meningioma.

BACKGROUND: Hepatocyte growth factor (HGF) is a cytokine that participates in multiple cell functions; it promotes proliferation, motility, and morphogenesis of epithelial cells. Some malignant tumors, such as breast carcinoma, bronchogenic carcinoma, and multiple myeloma, overexpress it and its receptor. Hepatocyte growth factor is also present in normal astrocytes; therefore, it is important to investigate whether HGF participates in the pathophysiology of malignant gliomas and other brain tumors. Intratumoral concentration of HGF in human intracranial neoplasms was measured and correlated with prognosis, tumor recurrence, vasogenic edema, cell proliferation index, and vascular density. METHODS: Hepatocyte growth factor concentration was measured in 62 intracranial tumors, including 16 anaplasic astrocytomas (AA), 16 glioblastoma multiformes (GM), 11 meningiomas, 9 hypophyseal adenomas, 7 oligodendrogliomas, and 3 cordomas, and in 4 samples of nonneoplastic brain tissue. The following parameters were correlated with HGF values: survival and tumor recurrence, cell proliferation index and vascular density as determined by immunohistopathologic analysis, and peritumoral edema as seen by magnetic resonance imaging. RESULTS: Hepatocyte growth factor concentration (pg/mL) was significantly higher in malignant gliomas (AA and GM) than in adenomas, oligodendrogliomas, and nonneoplastic brain tissue, but it was similar to that of meningiomas. Mean survival of patients with AA was 16.5 +/- 3.6 months and for patients with GM 12.3 +/- 1.3 months. Hepatocyte growth factor concentration was higher in GM than in AA (15,844 +/- 2504 vs. 7499 +/- 1703, P = 0.0375) and was correlated with the cell proliferation index and with poor prognosis. Likewise, mean tumoral concentration of HGF was higher in meningiomas that relapsed than in those without recurrence (22,887 +/- 6489 vs. 2090 +/- 497, P = 0.008). CONCLUSIONS: Intratumoral concentration of HGF in gliomas is associated with malignancy and poor prognosis. High HGF is also found in meningiomas and is related with long term recurrence. The current findings suggest that the routine measurement of HGF may be used as a predictive factor for planning therapeutic strategies in both malignant gliomas and meningiomas. The potential use of HGF inhibitors or antagonists for therapy of these tumors should be explored.

Antiproliferative effect of thalidomide alone and combined with carmustine against C6 rat glioma.

Thalidomide could have therapeutic applications in neoplasms and in other diseases, particularly those of autoimmune origin. The objective of this study was to investigate the effect of various doses of thalidomide on the growth of C6 glioma in rats, and to determine its effects on parameters of cell proliferation and angiogenesis. Additionally, we investigated a potential enhancement of the antitumoral action of thalidomide when combined with a low dose of the antineoplastic carmustine. C6 glioma cells were implanted subcutaneously in Wistar rats. A highly malignant glioma developed in 80% of animals. When the tumour reached 2.0 cm diameter thalidomide was administered at doses of 100, 200 or 400 mg/kg/day. When given at a dose of 400 mg/kg/day thalidomide significantly reduced the tumour volume, the mitotic index and cell proliferation but not the vascular density. The combination of thalidomide plus carmustine increased the inhibitory effect on tumoral growth. Our results indicate that thalidomide is effective against malignant glioma; apparently by an antiproliferative effect, rather than by inhibition of angiogenesis; when combined with carmustine it could increase the response of glioma to antineoplastic treatment.