Unsupervised machine learning models reveal predictive clinical markers of glioblastoma patient survival using white blood cell counts prior to initiating chemoradiation

Background

Glioblastoma is a malignant brain tumor requiring careful clinical monitoring even after primary management. Personalized medicine has suggested the use of various molecular biomarkers as predictors of patient prognosis or factors utilized for clinical decision-making. However, the accessibility of such molecular testing poses a constraint for various institutes requiring identification of low-cost predictive biomarkers to ensure equitable care.

Methods

We collected retrospective data from patients seen at Ohio State University, University of Mississippi, Barretos Cancer Hospital (Brazil), and FLENI (Argentina) who were managed for glioblastoma-amounting to 581 patient records documented using REDCap. Patients were evaluated using an unsupervised machine learning approach comprised of dimensionality reduction and eigenvector analysis to visualize the inter-relationship of collected clinical features.

Results

We discovered that the serum white blood cell (WBC) count of a patient during baseline planning for treatment was predictive of overall survival with an over 6-month median survival difference between the upper and lower quartiles of WBC count. By utilizing an objective PD-L1 immunohistochemistry quantification algorithm, we were further able to identify an increase in PD-L1 expression in glioblastoma patients with high serum WBC counts.

Conclusions

These findings suggest that in a subset of glioblastoma patients the incorporation of WBC count and PD-L1 expression in the brain tumor biopsy as simple biomarkers predicting glioblastoma patient survival. Moreover, machine learning models allow the distillation of complex clinical data sets to uncover novel and meaningful clinical relationships.

Unsupervised machine learning models reveal predictive markers of glioblastoma patient survival using white blood cell counts prior to initiating chemoradiation

Purpose

Glioblastoma is a malignant brain tumor requiring careful clinical monitoring even after primary management. Personalized medicine has suggested use of various molecular biomarkers as predictors of patient prognosis or factors utilized for clinical decision making. However, the accessibility of such molecular testing poses a constraint for various institutes requiring identification of low-cost predictive biomarkers to ensure equitable care.

Methods

We collected retrospective data from patients seen at Ohio State University, University of Mississippi, Barretos Cancer Hospital (Brazil), and FLENI (Argentina) who were managed for glioblastoma-amounting to nearly 600 patient records documented using REDCap. Patients were evaluated using an unsupervised machine learning approach comprised of dimensionality reduction and eigenvector analysis to visualize the inter-relationship of collected clinical features.

Results

We discovered that white blood cell count of a patient during baseline planning for treatment was predictive of overall survival with an over 6-month median survival difference between the upper and lower quartiles of white blood cell count. By utilizing an objective PDL-1 immunohistochemistry quantification algorithm, we were further able to identify an increase in PDL-1 expression in glioblastoma patients with high white blood cell counts.

Conclusion

These findings suggest that in a subset of glioblastoma patients the incorporation of white blood cell count and PDL-1 expression in the brain tumor biopsy as simple biomarkers predicting glioblastoma patient survival. Moreover, use of machine learning models allows us to visualize complex clinical datasets to uncover novel clinical relationships.

Information theory approaches to improve glioma diagnostic workflows in surgical neuropathology

Aims

Resource‐strained healthcare ecosystems often struggle with the adoption of the World Health Organization (WHO) recommendations for the classification of central nervous system (CNS) tumors. The generation of robust clinical diagnostic aids and the advancement of simple solutions to inform investment strategies in surgical neuropathology would improve patient care in these settings.

Methods

We used simple information theory calculations on a brain cancer simulation model and real‐world data sets to compare contributions of clinical, histologic, immunohistochemical, and molecular information. An image noise assay was generated to compare the efficiencies of different image segmentation methods in H&E and Olig2 stained images obtained from digital slides. An auto‐adjustable image analysis workflow was generated and compared with neuropathologists for p53 positivity quantification. Finally, the density of extracted features of the nuclei, p53 positivity quantification, and combined ATRX/age feature was used to generate a predictive model for 1p/19q codeletion in IDH‐mutant tumors.

Results

Information theory calculations can be performed on open access platforms and provide significant insight into linear and nonlinear associations between diagnostic biomarkers. Age, p53, and ATRX status have significant information for the diagnosis of IDH‐mutant tumors. The predictive models may facilitate the reduction of false‐positive 1p/19q codeletion by fluorescence in situ hybridization (FISH) testing.

Conclusions

We posit that this approach provides an improvement on the cIMPACT‐NOW workflow recommendations for IDH‐mutant tumors and a framework for future resource and testing allocation.

Accelerated epigenetic aging in adults with Down Syndrome in the Argentine population

BACKGROUND

Life expectancy of individuals with Down Syndrome (DS) is currently 60 years. From age 40 they have an increased risk of dementia and almost all of them have histopathological features of Alzheimer's disease (AD) in their brains. Also, it is known that the ε4 allele of the APOE gene and the R47H variant of TREM2 increase the risk of AD. DS is also associated with a group of clinical manifestations of accelerated aging. DNA methylation-based biomarkers of ageing (epigenetic clocks) can be assessed by different models. It is known that DNA methylation age (DNAm) has a positive correlation with chronological age in disomic individuals while DS subjects exhibit an age acceleration effect in blood and brain.

METHOD

We determined the DNAm age of a cohort of seven participants with chromosome 21 trisomy (confirmed by G-banding karyotyping). Median age was 49 years. Their cognitive status was assessed by clinical and neuropsychological evaluations. AD risk variants in APOE and TREM2 were analyzed by RFLP-PCR. DNAm age was assessed in peripheral blood leukocytes, using the Illumina 850K platform. We used the Horvath's epigenetic clock, based on the DNAm levels of 353 specific CpG sites.

RESULT

Five participants exhibited the ε3/ε3 genotype in APOE and two of them the ε3/ε4 genotype. We did not observe the R47H risk variant in TREM2 in this group. Five participants showed a significant biological age acceleration and one participant's DNAm age was similar to his chronological age. Of note, one participant showed a deceleration in the DNAm age. This participant also had multiple myeloma. It is known that the DNA methylation profile of multiple myeloma cells differs from normal plasma cells. On the other hand, we did not find a trend towards a greater presence of the risk allele ε4 or cognitive impairment in participants with a significant DNAm age acceleration.

CONCLUSION

The majority participants presented an acceleration in their biological age, but this fact was not correlated with a greater presence of the risk allele ε4 or cognitive impairment. This is the first dataset of DNA methylation ages of a cohort of people with Down Syndrome in Latin America.

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 Alzheimer's 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 Alzheimer's 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-Alzheimer's 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 Alzheimer's 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 group's model. Finally, the one-year conversion rate to dementia was 20% in the MCI cohort.

Abstract WP141: Genetic Polymorphisms Influence Carotid Atherosclerosis

Introduction: Genetic susceptibility affects atherosclerosis in humans. Polymorphisms of genes of angiotensin-converting enzyme (ACE), lipoprotein APOE (APOE), IL1 receptor antagonist (IL1Ra) and myeloperoxidase (MPO) are associated with several components of atherosclerotic disease. We evaluated allelic and genotypic frequencies and their association with age at presentation, vascular risk factors, and presence of symptoms in subjects with carotid atherosclerosis.

Methods: We studied Argentine patients with severe carotid atherosclerosis and controls from the general population. Age, vascular risk factors and presence of neurological symptoms were recorded. DNA was obtained from peripheral blood and PCR or PCR-RFLP were used to typify ACE, APOE, IL1Ra, and MPO genes. Allelic and genotypic frequencies were compared and genotypic susceptibility variants were established. Chi-square and good fit test were applied for differences between expected and observed frequencies.

Results: There were 137 patients, 36 women and 101 men, aged 67±8 years. Symptomatic subjects younger than 60 years had higher frequency of the alleles ACE-DD, associated to vasoconstriction, endothelial proliferation, oxidation, and apoptosis (p<0.01); IL1RN-12/22, associated to inflammation and apoptosis (p<0.01); and MPO*GA/AA, associated to less oxidative response and proatherogenic (p<0.05). Subjects older than 60 years had a genetic profile similar to the general population without atherosclerosis, with similar prevalence of ACE-ID/II, IL1RN-11, and MPO-GG and a higher frequency of APOE23, 24 and 34m. Independent associations of ACE*D and IL1RN*2 with dyslipidemia and of MPO-GA and APOE-34 with hypertension were observed.

Conclusions: Subjects with carotid atherosclerosis are genetically different from the general population. Carriers of certain gene variants were predominant among atherosclerotic subjects, suggesting susceptibility, and others were more prevalent in controls, suggesting protection. Some polymorphisms and their combinations are associated with occurrence of symptomatic disease at an earlier age. The genetic profile of older patients does not substantially differ from the general population.

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.

Analysis of C9orf72 in patients with frontotemporal dementia and amyotrophic lateral sclerosis from Argentina

Pathologic expansion of the G4C2 repeat in C9orf72 is the main genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). To evaluate the frequency of the G4C2 expansion in a Latin American cohort of FTD and ALS patients, we used a 2-step genotyping strategy. For FTD, we observed an overall expansion frequency of 18.2% (6 of 33 unrelated cases). Moreover, the C9orf72 expansion accounted for 37.5% of all familial FTD cases (6 of 16 families). The expansion frequency in sporadic ALS cases was 2% (1 of 47 unrelated patients), whereas we observed the expansion in 1 of 3 families with a positive history for ALS. Overall, the expansion frequency in our FTD group was similar to that reported for patients in Europe and North America, whereas the frequency in our sporadic ALS group was significantly lower. To our knowledge, this is the first report on the frequency of the C9orf72 expansion in a Latin American population.

Specific Preferences in Lineage Choice and Phenotypic Plasticity of Glioma Stem Cells Under BMP4 and Noggin Influence

Although BMP4-induced differentiation of glioma stem cells (GSCs) is well recognized, details of the cellular responses triggered by this morphogen are still poorly defined. In this study, we established several GSC-enriched cell lines (GSC-ECLs) from high-grade gliomas. The expansion of these cells as adherent monolayers, and not as floating neurospheres, enabled a thorough study of the phenotypic changes that occurred during their differentiation. Herein, we evaluated GSC-ECLs' behavior toward differentiating conditions by depriving them of growth factors and/or by adding BMP4 at different concentrations. After analyzing cellular morphology, proliferation and lineage marker expression, we determined that GSC-ECLs have distinct preferences in lineage choice, where some of them showed an astrocyte fate commitment and others a neuronal one. We found that this election seems to be dictated by the expression pattern of BMP signaling components present in each GSC-ECL. Additionally, treatment of GSC-ECLs with the BMP antagonist, Noggin, also led to evident phenotypic changes. Interestingly, under certain conditions, some GSC-ECLs adopted an unexpected smooth muscle-like phenotype. As a whole, our findings illustrate the wide differentiation potential of GSCs, highlighting their molecular complexity and paving a way to facilitate personalized differentiating therapies.

Correlation between EGFR amplification and the expression of microRNA-200c in primary glioblastoma multiforme

Extensive infiltration of the surrounding healthy brain tissue is a critical feature in glioblastoma. Several miRNAs have been related to gliomagenesis, some of them related with the EGFR pathway. We have evaluated whole-genome miRNA expression profiling associated with different EGFR amplification patterns, studied by fluorescence in situ hybridization in tissue microarrays, of 30 cases of primary glioblastoma multiforme, whose clinicopathological and immunohistochemical features have also been analyzed. MicroRNA-200c showed a very significant difference between tumors having or not EGFR amplification. This microRNA plays an important role in epithelial-mesenchymal transition, but its implication in the behavior of glioblastoma is largely unknown. With respect to EGFR status our cases were categorized into three groups: high level EGFR amplification, low level EGFR amplification, and no EGFR amplification. Our results showed that microRNA-200c and E-cadherin expression are down-regulated, while ZEB1 is up-regulated, when tumors showed a high level of EGFR amplification. Conversely, ZEB1 mRNA expression levels were significantly lower in the group of tumors without EGFR amplification. Tumors with a low level of EGFR amplification showed ZEB1 expression levels comparable to those detected in the group with a high level of amplification. In this study we provide what is to our knowledge the first report of association between microRNA-200c and EGFR amplification in glioblastomas.

Gerstmann-Sträussler-Scheinker syndrome with variable phenotype in a new kindred with PRNP-P102L mutation

Gerstmann-Sträussler-Scheinker syndrome (GSS) is a dominantly inherited disorder belonging to the group of transmissible human spongiform encephalopathies or prion diseases. Several families affected by GSS with patients carrying mutations in the prion protein gene have been described worldwide. We report clinical, genealogical, neuropathology and molecular study results from two members of the first Argentine kindred affected by GSS. Both family members presented a frontotemporal-like syndrome, one with and the other without ataxia, with different lesions on neuropathology. A Pro to Leu point mutation at codon 102 (P102L) of the prion protein gene was detected in one of the subjects studied. The pathogenic basis of phenotypic variability observed in this family remains unclear, but resembles that observed in other P102L GSS patients from the same family.

Creutzfeldt-Jakob disease surveillance in Argentina, 1997-2008

BACKGROUND

Epidemiological data on Creutzfeldt-Jakob disease (CJD) from Latin America are limited. We present a comprehensive epidemiological survey on CJD patients in Argentina based on systematic surveillance between 1997 and 2008.

METHODS

A CJD Surveillance Referral Center (SRC) was established in Argentina in 1997; previously a Neuropathology Referral Center was used from 1983 to 1996. All suspected cases referred to the SRC were classified using established criteria on the basis of information derived from the following: clinical data form, EEG, MRI (both for central review), cerebrospinal fluid (CSF) for protein 14-3-3 Western blot (WB), autopsy or biopsy material for neuropathology, prion protein (PrP) immunohistochemistry and PrP WB, as well as blood for DNA studies (when brain tissue was not available).

RESULTS

Of the 517 patients referred to the SRC between 1997 and 2008, 211 (40.8%) had CJD or other transmissible spongiform encephalopathies (TSEs) (definite or probable). Possible cases totaled 14.5%, while cases with no WHO criteria accounted for 16.4%. Non-CJD cases excluded by biopsy/autopsy or during follow-up corresponded to 28.2% of the 517 referrals. Main differential diagnoses included neurodegenerative diseases such as Alzheimer's disease, frontotemporal dementia, vascular, metabolic or viral encephalopathy, and Hashimoto's disease. Five percent of referred patients ultimately recovered. Eighty-three percent of TSE cases were sporadic CJD; 17% were genetic, mainly E200K (15.6%); the remaining 1.4% included an octarepeat insertion and two Gerstmann-Sträussler-Scheinker cases (P102L). Seventy-four of 100 definite cases had frozen tissue available for molecular subtyping (PrP(Sc)/codon 129). CSF protein 14-3-3 WB sensitivity was 72.3% and specificity was 92.1%. Clinical diagnostic criteria for probable CJD when compared to definite diagnosis by neuropathology showed 71.3% sensitivity, 86.2% specificity, 94.4% positive predictive value and 48% negative predictive value. Country incidence increased over time and reached 0.85 cases per million in 2008, with the highest rate detected in the city of Buenos Aires (1.8). Districts with 6% of the total population have never reported suspected cases.

CONCLUSION

In spite of an increase in incidence observed over time, the difference between Buenos Aires city, where the incidence is comparable to that of smaller European countries with higher population density, and the incidence observed in the rest of the country suggests underreporting in nonmetropolitan areas, probably due to a lack of access to specialized medical facilities. CSF WB sensitivity results for protein 14-3-3 were probably linked to the fact that testing was not routinely repeated during the course of the disease, when earlier test results had been negative. The spectrum of molecular CJD subtypes observed did not differ from other countries in Europe. No iatrogenic or variant CJD cases were identified. The sensitivity and negative predictive value of clinical diagnostic criteria for probable CJD (which includes EEG and/or CSF protein 14-3-3 levels) may have been resulted from confirmed cases not meeting probable criteria before autopsy, due to a lack of ancillary tests such as EEG and/or CSF 14-3-3 WB, or because negative tests were not repeated during follow-up.

Comparative metabolic profiling of paediatric ependymoma, medulloblastoma and pilocytic astrocytoma

Brain tumours are the most common solid tumours in children and a major cause of childhood mortality. The most common paediatric brain tumours include ependymomas, cerebellar astrocytomas and medulloblastomas. These brain tumours are highly heterogeneous regarding their histology, prognosis and therapeutic response. Subtle biochemical changes can be detected in intact tissues by High-Resolution Proton Magnetic Angle Spinning Spectroscopy (HR-MAS) revealing the status of tumour microheterogeneity and metabolic alterations before they are morphologically detectable. In this study, we present metabolic profiles by HR-MAS of 20 intact tissue samples from paediatric brain tumours. Tumour types include ependymoma, medulloblastoma and pilocytic astrocytoma. The metabolic characterization of paediatric brain tumour tissue by HR-MAS spectroscopy provided differential patterns for these tumours. The metabolic composition of the tumour tissue was highly consistent with previous in vivo and ex vivo studies. Some resonances detected in this work and not previously observed by in vivo spectroscopy also show potential in determining tumour type and grade (fatty acids, phenylalanine, glutamate). Overall, this work suggests that the additional information obtained by NMR metabolic profiling applied to tissue from paediatric brain tumours may be useful for assessing tumour grade and determining optimum treatment strategies.

Loss of heterozygosity at 1p-19q induces a global change in oligodendroglial tumor gene expression

Oligodendroglial tumors presenting loss of heterozygosity (LOH) at 1p and 19q have been shown to be sensitive to chemotherapy, thus making 1p-19q status testing a key aspect in oligodendroglioma diagnosis and prognosis. Twenty-nine tumor samples (19 oligodendrogliomas, 10 oligoastrocytomas) were analyzed in order to obtain a molecular profile identifying those bearing 1p-19q LOH. Other genomic anomalies usually present in gliomas, such as EGFR amplification, CDKN2A/ARF deletion, 10q LOH and TP53 mutation, were also studied. Tumors with 1p-19q LOH overexpressed genes related to neurogenesis. Genes linked to immune response, proliferation and inflammation were overexpressed in the group with intact 1p-19q; this group could in turn be further divided in two subgroups: one overexpressing genes involved in immune response and inflammation that did not show major genetic aberrations other than the TP53 mutation and EGFR trisomy in a few cases, and another overexpressing genes related to immune response and proliferation that had a predominance of samples carrying several anomalies and presenting worse outcomes. This molecular signature was validated by analyzing a set of ten tumor samples (three oligodendrogliomas, seven oligoastrocytomas); all ten samples were correctly assigned. LOH at 1p-19q results in haploinsufficiency and copy number reduction of several genes, including NOTCH 2; this phenomenon produces a global change in gene expression inducing a pro-neural status that results in restrictions to cell migration and proliferation. Tumors without LOH at 1p-19q exhibit the opposite characteristics, explaining their more aggressive behavior.

Seminested Polymerase Chain Reaction (PCR) for Detecting Helicobacter pylori DNA in Carotid Atheromas

A polymerase chain reaction (PCR) method for the detection of the glmM gene, selected as Helicobacter pylori target sequence, was improved. While performing pathogenicity island cagA gene detection to discriminate pathogenic strains in atherosclerotic carotid samples, several cagA-positive but glmM-negative samples were found. Polymorphisms present in the region amplified in the nested PCR reaction could explain this result; primers were therefore designed to perform a seminested reaction; this modification optimized sensitivity while maintaining specificity. A real-time PCR for Helicobacter DNA detection was also setup. The combination of all 4 PCR reactions detected 83% of H. pylori DNA-positive samples in atherosclerotic carotid tissue, 64% of which were cagA gene positive.

Phosphorylation of c-Fos by members of the p38 MAPK family. Role in the AP-1 response to UV light

Exposure to sources of UV radiation, such as sunlight, induces a number of cellular alterations that are highly dependent on its ability to affect gene expression. Among them, the rapid activation of genes coding for two subfamilies of proto-oncoproteins, Fos and Jun, which constitute the AP-1 transcription factor, plays a key role in the subsequent regulation of expression of genes involved in DNA repair, cell proliferation, cell cycle arrest, death by apoptosis, and tissue and extracellular matrix remodeling proteases. Besides being regulated at the transcriptional level, Jun and Fos transcriptional activities are also regulated by phosphorylation as a result of the activation of intracellular signaling cascades. In this regard, the phosphorylation of c-Jun by UV-induced JNK has been readily documented, whereas a role for Fos proteins in UV-mediated responses and the identification of Fos-activating kinases has remained elusive. Here we identify p38 MAPKs as proteins that can associate with c-Fos and phosphorylate its transactivation domain both in vitro and in vivo. This phosphorylation is transduced into changes in its transcriptional ability as p38-activated c-Fos enhances AP1-driven gene expression. Our findings indicate that as a consequence of the activation of stress pathways induced by UV light, endogenous c-Fos becomes a substrate of p38 MAPKs and, for the first time, provide evidence that support a critical role for p38 MAPKs in mediating stress-induced c-Fos phosphorylation and gene transcription activation. Using a specific pharmacological inhibitor for p38alpha and -beta, we found that most likely these two isoforms mediate UV-induced c-Fos phosphorylation in vivo. Thus, these newly described pathways act concomitantly with the activation of c-Jun by JNK/MAPKs, thereby contributing to the complexity of AP1-driven gene transcription regulation.

[Creutzfeldt-Jakob encephalopathy with mutation E200K. Report of a "sporadic" case]

INTRODUCTION

Creutzfeldt Jakob disease (CJD) has the highest incidence of the whole group of transmissible spongiform encephalopathies or prion diseases, which have the unique feature among all pathologies, to be able to appear as infectious/iatrogenic, sporadic or hereditary, being common to all, the deposition of an abnormal prion protein (PrPSc,CJres) in the central nervous system. More than 20 mutations of the gene (PRNP) that encodes the prion protein have been described. We here report a case of CJD(E200K) refered as probable 'sporadic' according to WHO.

METHODS

clinical, pathologic, and molecular features of the disease were characterized using EEG, neuropathology, prionprotein (PrP) Western blot and gene (PRNP) analysis.

RESULTS

The patient developed visual hallucinations, myoclonus, memory loss, tremor, disbasia and generalized convulsives seizures dying six months after onset. On neuropathologic examination, spongiform changes were observed and PrP immunopositivity detected. Western blot analysis showed the presence of proteinaseK (PK)-resistant PrP (PrPres) with the nonglycosylatedisoform of approximately 21 kd, and DNA restriction fragment length polymorphism (RFLP) analysis showed the E200K mutation.

DISCUSSION

The PRNP(E200K) mutation is the most frequent cause of the hereditary-familial CJD (fCJD). Clusters of this variety have been described in Chileans, Slovaks from Orava, Jews Israelies of Libyan origin, and Japanese. There was no available data of affected relatives of the patient which have suggested he was fCJD, but due to his Chilean origin PRNP studies were carried out. In fact the clinical and pathology of this familial form, with remarkable exceptions, resembles sporadic cases but has a greater incidence, in these groups than sporadic in the general population.

CONCLUSION

This patient, although clinically reported as probable 'sporadic', after molecular characterization resulted a CJD(E200K) probably belonging to the Chilean cluster.

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-1 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.

Partial characterization of guanylyl cyclase activity in calf thyroid

The aim of the present study was to perform the partial characterization of the enzyme guanylyl cyclase (GC) in bovine thyroid. The results obtained showed the presence of two types of GC: one is soluble and comprises around 79% of total activity, while the other is particulate. Treatment with 1% Triton X-100 increased both activities. When the kinetics of the enzyme was analyzed, using the complex MnGTP as a substrate, the results showed a Michaelis type kinetics for the soluble enzyme, with a Km of 0.037 mM, whereas the particulate GC showed a positive allosteric behavior with a S0.5 of 0.214 mM and a Hill coefficient of 1.9, indicating that the enzyme has at least two binding sites for the substrate. When the influence of different Mn2+ concentrations was studied, a positive allosteric behavior for the soluble GC was found, with a S0.5 of 1.2 mM and a Hill coefficient of 2.2. The kinetics of the particulate enzyme under similar conditions was of Michaelis type, with a Km of 0.752 mM. Although the enzyme is highly dependent on Mn2+, it was of interest to investigate the possible effects of other divalent cations, such as Ca2+ and Mg2+. The replacement of Mn2+ for Mg2+ caused a complete disappearance of the particulate enzyme activity, while the soluble activity decreased by 85%. Addition of Ca2+ had no effect on either GC. However, with suboptimum. concentrations of Mn2+, high Ca2+ concentration caused an increase in soluble activity, but it comprised only 20% of maximum activity with optimum Mn2+ concentrations. With the particulate enzyme a slight but significant inhibition was observed.

Multicellular stalk-like structures in Saccharomyces cerevisiae

Stalk formation is a novel pattern of multicellular organization. Yeast cells which survive UV irradiation form colonies that grow vertically to form very long (0.5 to 3.0 cm) and thin (0.5 to 4 mm in diameter) multicellular structures. We describe the conditions required to obtain these stalk-like structures reproducibly in large numbers. Yeast mutants, mutated for control of cell polarity, developmental processes, UV response, and signal transduction cascades were tested and found capable of forming stalk-like structures. We suggest a model that explains the mechanism of stalk formation by mechanical environmental forces. We show that other microorganisms (Candida albicans, Schizosaccharomyces pombe, and Escherichia coli) also form stalks, suggesting that the ability to produce stalks may be a general property of microorganisms. Diploid yeast stalks sporulate at an elevated frequency, raising the possibility that the physiological role of stalks might be disseminating spores.

Identification of a dual specificity kinase that activates the Jun kinases and p38-Mpk2

One Ras-dependent protein kinase cascade leading from growth factor receptors to the ERK (extracellular signal-regulated kinases) subgroup of mitogen-activated protein kinases (MAPKs) is dependent on the protein kinase Raf-1, which activates the MEK (MAPK or ERK kinase) dual specificity kinases. A second protein kinase cascade leading to activation of the Jun kinases (JNKs) is dependent on MEKK (MEK kinase). A dual-specificity kinase that activates JNK, named JNKK, was identified that functions between MEKK and JNK. JNKK activated the JNKs but did not activate the ERKs and was unresponsive to Raf-1 in transfected HeLa cells. JNKK also activated another MAPK, p38 (Mpk2; the mammalian homolog of HOG1 from yeast), whose activity is regulated similarly to that of the JNKs.

The UV response involving the Ras signaling pathway and AP-1 transcription factors is conserved between yeast and mammals

UV irradiation of mammalian cells activates AP-1 through a Ras-dependent pathway, independently of DNA damage. We show that the yeast S. cerevisiae has a remarkably similar UV response involving the AP-1 factor Gcn4, which is distinct from the DNA damage response. Transcriptional activation of HIS3 and HIS4 by Gcn4 is triggered by UV irradiation in a Ras-dependent fashion. Moreover, resistance of yeast to UV irradiation is correlated with the level of Ras activity and Gcn4 function. Like mammalian cells in which activated Ras leads to increased c-Jun synthesis and phosphorylation, the effects in yeast involve increased translation of GCN4 mRNA and a posttranslational event. However, this effect on GCN4 translation is different from the response to amino acid or purine starvation. Therefore, a UV signaling pathway involving Ras and AP-1 is an ancient and universal mechanism involved in protection against damage to cellular components other than DNA.

Characterization of a Gi-protein from Trypanosoma cruzi epimastigote membranes

A guanosine 5'-[gamma-[35S]thio]triphosphate-binding activity was detergent-extracted from Trypanosoma cruzi membranes. This binding activity was co-eluted from gel-filtration columns with a factor which, in a heterologous reconstitution system, blocks glucagon stimulation of adenylate cyclase activity in liver membranes. ADP-ribosylation of these membranes by pertussis toxin eliminated this blocking capacity. Incubation of T. cruzi membranes with activated pertussis toxin and [adenylate-32P]NAD+ led to the incorporation of radioactivity into a labelled product with an apparent M(r) of approx. 43,000. Crude membranes were electrophoresed on SDS/polyacrylamide gels and analysed, by Western blotting, with GA/1 anti-alpha common, AS/7 anti-alpha t, anti-alpha i1 and anti-alpha i2 polyclonal antibodies. These procedures led to the identification of a specific polypeptide band of about 43 kDa. Another polypeptide reacting with the SW/1 anti-beta antibody, of about 30 kDa, was also detected in the membrane fraction.