Horacio Martinetto

Adenylate cyclase activity in Cyanobacteria: activation by Ca2+-calmodulin and a calmodulin-like activity

An adenylate cyclase activity was partially characterized in the cyanobacterium Anabaena sp. The enzyme activity is found in soluble cell fractions and shows an apparent molecular weight of about 183,400. This adenylate cyclase is activated by Ca2+ and bovine brain or spinach calmodulin and it is inhibited by EGTA and some phenothiazine derivatives. Furthermore, Anabaena sp. extracts contain a calmodulin-like activity which stimulates bovine brain cyclic AMP phosphodiesterase and the Anabaena adenylate cyclase. EGTA and phenothiazine derivatives block the cyanobacterial modulator effect.

Factors from Trypanosoma cruzi Interacting with AP-1 Sequences

Interaction between factors from Trypanosoma cruzi extracts and AP‐1 sequences was studied by electrophoretic mobility shift assays. Using a double‐stranded probe carrying the AP‐1 sequence from the SV40 promoter, three specific complexes designated A, B, and C were detected. Complexes A and C were formed when using single‐stranded probes. The relative amount of complex B, specific for double‐stranded DNA, increased as a function of probe length. Complexes were stabilized by cross‐linking with UVC irradiation and resolved on denaturing SDS‐PAGE. Complex A generated bands of 60‐ and 39 kDa; complex B produced two bands of 46‐ and 43 kDa; and complex C generated one band of 43 kDa. The AP‐I binding activity was much higher in purified nuclear preparations than in soluble fractions, and was detected in crude extracts from the three forms of the parasite. The binding signal, however, was much stronger in amastigote and trypomastigote than in the epimastigote forms. Specific binding was increased by oxidative stress. Antibodies raised against peptides corresponding to conserved domains of mammalian c‐Jun and c‐Fos detected bands of 40‐ and 60 kDa, respectively, in a nuclear epimastigote preparation.

The NSL chromatin-modifying complex subunit KANSL2 regulates cancer stem-like properties in glioblastoma that contribute to tumorigenesis

KANSL2 is an integral subunit of the nonspecific lethal (NSL) chromatin-modifying complex that contributes to epigenetic programs in embryonic stem cells. In this study, we report a role for KANSL2 in regulation of stemness in glioblastoma (GBM), which is characterized by heterogeneous tumor stem-like cells associated with therapy resistance and disease relapse. KANSL2 expression is upregulated in cancer cells, mainly at perivascular regions of tumors. RNAi-mediated silencing of KANSL2 in GBM cells impairs their tumorigenic capacity in mouse xenograft models. In clinical specimens, we found that expression levels of KANSL2 correlate with stemness markers in GBM stem-like cell populations. Mechanistic investigations showed that KANSL2 regulates cell self-renewal, which correlates with effects on expression of the stemness transcription factor POU5F1. RNAi-mediated silencing of POU5F1 reduced KANSL2 levels, linking these two genes to stemness control in GBM cells. Together, our findings indicate that KANSL2 acts to regulate the stem cell population in GBM, defining it as a candidate GBM biomarker for clinical use. Cancer Res; 76(18); 5383-94. ©2016 AACR.

Evaluation of Cerebrospinal Fluid Neurofilament Light Chain as a Routine Biomarker in a Memory Clinic

Systematic evaluation of biomarkers in representative populations is needed to validate their clinical utility. In this work, we assessed the diagnostic performance of cerebrospinal fluid (CSF) neurofilament light chain (NfL) in a neurocognitive clinical setting. A total of 51 patients with different cognitive clinical syndromes and 11 cognitively normal individuals were evaluated in a memory clinic in Argentina. Clinical conditions included mild cognitive impairment (MCI, n = 12), dementia of Alzheimers type (DAT, n = 14), behavioral variant frontotemporal dementia (bvFTD, n = 13), and primary progressive aphasia (logopenic [n = 6], semantic [n = 2], and nonfluent [n = 4]). We quantified CSF NfL and core Alzheimers disease biomarkers using commercially available ELISA kits. Cortical thickness was analyzed on brain magnetic resonance imaging scans from 10 controls and 10 patients. CSF NfL was significantly increased in MCI, FTD, and DAT patients compared with controls (Kruskal-Wallis, p < .0001). Interestingly, receiver operating characteristic curve analysis showed the highest area under the curve (AUC) value when analyzing control versus bvFTD patients (AUC = 0.9441). Also, we observed a marginally significant correlation between NfL levels and left orbitofrontal cortex thickness in a small group of patients with FTD. Overall, our results further support CSF NfL as a promising biomarker in the diagnostic workup of bvFTD.

Argentina-Alzheimer's disease neuroimaging initiative (Arg-ADNI): neuropsychological evolution profile after one-year follow up

The Argentina-Alzheimers disease neuroimaging initiative (Arg-ADNI) study is a longitudinal prospective cohort of 50 participants at a single institution in Buenos Aires, Argentina. Longitudinal assessments on a neuropsychological test battery were performed on 15 controls, 24 mild cognitive impairment (MCI) patients and 12 Alzheimers disease (AD) dementia patients. In our study population, there was a high prevalence of positive AD biomarkers in the AD group, 92.3% (12/13); and a low prevalence in the normal controls, 20%; almost half (48%) of the patients diagnosed with MCI had positive amyloid detection. After a one year, the significant differences found at baseline on neuropsychological testing were similar at the follow-up assessment even though the AD group had significantly altered its functional performance (FAQ and CDR). The exception was semantic fluency, which showed greater impairment between the AD group and MCI and normal controls respectively. For these tests, the addition of AD biomarkers as a variable did not significantly alter the variations previously found for the established clinical groups model. Finally, the one-year conversion rate to dementia was 20% in the MCI cohort.

CORTICAL THICKNESS FOLLOW-UP AFTER ONE YEAR IN ADNI-ARGENTINA COHORT

P1-451 CORTICALTHICKNESS FOLLOW-UP AFTER ONE YEAR IN ADNI-ARGENTINA COHORT Ismael Luis Calandri, Ignacio Demey, Patricio Alexis Chrem Mendez, Gabriela Cohen, Maria Julieta Russo, Ezequiel Surace, Horacio Martinetto, Federico Nahas, Maria Eugenia Martin, Paula Harris, Jorge Campos, Gustavo Sevlever, Silvia Vazquez, Allegri F. Ricardo, Ra ul Carrea Institute for Neurological Research (FLENI), Buenos Aires, Argentina; Hospital Brit anico de Buenos Aires, Buenos Aires, Argentina; Ra ul Carrea Institute for Neurological Research (FLENI), Buenos Aires, Argentina. Contact e-mail: ismaelcalandri@gmail.com