Increased incidence of choroid plexus carcinoma due to the germline TP53 R337H mutation in southern Brazil

Background

Choroid plexus carcinomas (CPC) are rare tumors predominantly found in children. Given the high frequency of the germline R337H mutation in the TP53 gene in southern Brazil, we have evaluated the frequency of the R337H mutation in families with CPC in children.

Methodology/Principal Findings

The present series included 29 patients that were admitted to the same institution from 1992 to 2010, including 22 children with CPC (0.08–13.6 years of age at diagnosis) and 7 children with papilloma of the choroid plexus (Pp; 0.5–9.8 years of age). Surgical resection was possible in 28 children. Blood and/or tumor DNA was extracted and analyzed using PCR-RFLP and results were confirmed by sequencing 240 bp of the TP53 exon 10. The patients, all parents, and some relatives submitted samples for blood DNA analysis. In addition, we have also examined the presence of the mutation in DNA from paraffin-embedded tumor samples to evaluate loss of heterozygosity. We found 63.3% (14/22) of the CPC patients positive for the germline R337H mutation; CPC samples were either heterozygous (n = 7), lost only the wild-type (n = 4), or only the R337H copy (n = 2). One CPC sample was not available. All Pp cases (7/7, 100%) were negative for R337H. Cure (>5 years survival free of disease) was observed in 18.1% of the CPC cases with the R337H mutation (2/11), 71.4% of the Pp (5/7), and 25% of CPC cases negative for the R337H mutation (2/8). Family history of cancer (with 2 or more cancer cases) was exclusively identified on the parental side segregating the R337H mutation, and 50% (7/14) of them were compatible with Li-Fraumeni-like syndrome.

Significance

Our results show for the first time that the R337H TP53 mutation is responsible for 63% of the CPC cases in children, suggesting a higher incidence of CPC in southern Brazil.     

Inactivation of hepatocyte protein kinase C by carbon tetrachloride: involvement of drug's metabolic activation and prooxidant effect

The involvement of CCl4 biotransformation mechanism in decreasing the Protein Kinase C activity has been analyzed in hepatocytes isolated from phenobarbital-pretreated rats. A significant inhibition (55%) and an almost total disappearance (87%) of the enzyme activity were observed at 15 min and at 30 min incubation with CCl4, respectively. Cell preincubation with Trolox or desferrioxamine allowed a marked whilst not complete protection of both cytosolic and particulate Protein Kinase C activity. These results show that the CCl4 reactive metabolites play a primary role in hepatocyte Protein Kinase C impairment and suggest that besides lipid peroxidation other mechanisms -possibly a derangement of Ca2+ homeostasis- may be involved in this process.     

Neuropathological findings processed by artificial neural networks (ANNs) can perfectly distinguish Alzheimer's patients from controls in the Nun Study

Background  

Many reports have described that there are fewer differences in AD brain neuropathologic lesions between AD patients and control subjects aged 80 years and older, as compared with the considerable differences between younger persons with AD and controls. In fact some investigators have suggested that since neurofibrillary tangles (NFT) can be identified in the brains of non-demented elderly subjects they should be considered as a consequence of the aging process. At present, there are no universally accepted neuropathological criteria which can mathematically differentiate AD from healthy brain in the oldest old.     

Nucleotide Phosphohydrolase in Purified Vaccinia Virus

Purified infectious vaccinia virus has been shown to contain an enzyme or enzymes that remove the terminal phosphate group from adenosine triphosphate (ATP), guanosine triphosphate (GTP), uridine triphosphate (UTP), and cytidine triphosphate (CTP). The K(m) for ATP of this enzyme is 5.5 x 10(-4)m, and the relative rates of the reaction with ATP, GTP, UTP, and CTP are 1.00, 0.34, 0.15, and 0.29, respectively. The virus enzyme does not react with any of the diphosphates. The rate of the reaction is proportional to the amount of virus added and is linear for 130 min. The virus nucleotide phosphohydrolase activity is greatly stimulated by Mg(++) and very slightly stimulated by Ca(++). The small residual activity observed in the absence of divalent cations is completely inhibited by ethylenediaminetetraacetic acid. Neither Na(+) nor K(+) ions, nor any mixture of these, was found to stimulate the reaction significantly, and ouabain, at 10(-4)m, inhibited the reaction by only 27%. The response of the vaccinia enzyme to mono- and divalent cations and to ouabain indicates that the vaccinia enzyme has different properties from those associated with microsomes and mitochondria.     

Mutation induction in Chinese hamster lung V79 cells by five alk-2-enals produced by lipid peroxidation

Five alk-2-enals--pent-2-enal, hex-2-enal, hept-2-enal, oct-2-enal and non-2-enal--produced by lipid peroxidation were tested for mutagenic activity in V79 Chinese hamster cells. At concentrations ranging from 0.003 to 0.3 mM all 5 alk-2-enals induced a dose-dependent increase in the frequency of 6-thioguanine-resistant mutants, and their mutagenic potency was found to increase with the length of the carbon chain. In contrast, only hept-2-enal produced a statistically significant increase in the number of mutations to ouabain resistance.     

Evolution of Hypervariable Region 1 of Hepatitis C Virus in Primary Infection

The hypervariable region 1 (HVR-1) of the putative envelope encoding E2 region of hepatitis C virus (HCV) RNA was analyzed in sequential samples from three patients with acute type C hepatitis infected from different sources to address (i) the dynamics of intrahost HCV variability during the primary infection and (ii) the role of host selective pressure in driving viral genetic evolution. HVR-1 sequences from 20 clones per each point in time were analyzed after amplification, cloning, and purification of plasmid DNA from single colonies of transformed cells. The intrasample evolutionary analysis (nonsynonymous mutations per nonsynonymous site [K_a], synonymous mutations per synonymous site [K_s], K_a/K_s ratio, and genetic distances [gd]) documented low gd in early samples (ranging from 2.11 to 7.79%) and a further decrease after seroconversion (from 0 to 4.80%), suggesting that primary HCV infection is an oligoclonal event, and found different levels and dynamics of host pressure in the three cases. The intersample analysis (pairwise comparisons of intrapatient sequences; rK_a, rK_s, rK_a/rK_s ratio, and gd) confirmed the individual features of HCV genetic evolution in the three subjects and pointed to the relative contribution of either neutral evolution or selective forces in driving viral variability, documenting that adaptation of HCV for persistence in vivo follows different routes, probably representing the molecular counterpart of the viral fitness for individual environments.