Childhood liver tumors in Argentina: Incidence trend and survival by treatment center. A report from the national pediatric cancer registry, ROHA network 2000-2015.

BACKGROUND: Information on the epidemiology of pediatric liver tumors in Latin America is limited. PURPOSE: To describe the incidence of liver tumors in a pediatric registry in Argentina according to geographic region, national trends over 16 years, and survival related to stage, age, sex, and care center. METHODS: Newly diagnosed liver tumors cases are registered in the Argentine Pediatric Oncology Hospital Registry (ROHA) with an estimated coverage of 91% of national cases. Age-standardized incidence rate per millon (ASR) was calculated based on the National Vital Statistics Reports. Five-year overall survival (OS) was estimated using the Kaplan-Meier method. The log-rank test was used to compare subgroup survival. RESULTS: Two hundred seven cases of hepatoblastoma (HB) and 73 of hepatocellular carcinoma (HCC) were identified. ASR of liver tumors was 1.8/million (95% confidence Interval [CI], 1.6-2.0) per year. ASR was 1.4 (1.2-1.6) for HB and 0.4 (0.3-0.5) for HCC. For HB, the highest incidence was found in the northwest region including the Altiplano. OS was 60.4% (53.4-66.8) for HB and 36.1% (25.2-47.2) for HCC. Five-year survival rate of children with metastatic HB treated at liver transplant hospitals (LTH) was 54.2% (30.3-73.0) compared to 13.3% (2.2-34.6) for those seen at other hospitals (OH) (P = .02), while for HCC this rate was 46.3% (30.7-60.6) at LTH compared to 17.5% (3.1-41.9) at OH (P = .01). CONCLUSIONS: The incidence rate of pediatric liver tumors was stable over the 16-year study period. Patients may benefit if at treatment initiation they are evaluated jointly with LTH specialists to define treatment strategies.

Does the Presence of Scrapie Affect the Ability of Current Statutory Discriminatory Tests To Detect the Presence of Bovine Spongiform Encephalopathy?

Current European Commission (EC) surveillance regulations require discriminatory testing of all transmissible spongiform encephalopathy (TSE)-positive small ruminant (SR) samples in order to classify them as bovine spongiform encephalopathy (BSE) or non-BSE. This requires a range of tests, including characterization by bioassay in mouse models. Since 2005, naturally occurring BSE has been identified in two goats. It has also been demonstrated that more than one distinct TSE strain can coinfect a single animal in natural field situations. This study assesses the ability of the statutory methods as listed in the regulation to identify BSE in a blinded series of brain samples, in which ovine BSE and distinct isolates of scrapie are mixed at various ratios ranging from 99% to 1%. Additionally, these current statutory tests were compared with a new in vitro discriminatory method, which uses serial protein misfolding cyclic amplification (sPMCA). Western blotting consistently detected 50% BSE within a mixture, but at higher dilutions it had variable success. The enzyme-linked immunosorbent assay (ELISA) method consistently detected BSE only when it was present as 99% of the mixture, with variable success at higher dilutions. Bioassay and sPMCA reported BSE in all samples where it was present, down to 1%. sPMCA also consistently detected the presence of BSE in mixtures at 0.1%. While bioassay is the only validated method that allows comprehensive phenotypic characterization of an unknown TSE isolate, the sPMCA assay appears to offer a fast and cost-effective alternative for the screening of unknown isolates when the purpose of the investigation was solely to determine the presence or absence of BSE.

Commentary: toward an improved understanding of administrative segregation.

The questions raised by O'Keefe et al. challenge us to think clearly about the intent of incarceration generally and the objective of administrative segregation in particular. Our comments address several points: the study's methodology, the context of administrative segregation, several attendant pragmatic concerns linked to its practice, and the challenges of understanding the needs and motivations of individual offenders.

Four BSE cases with an L-BSE molecular profile in cattle from Great Britain.

Bovine spongiform encephalopathy (BSE) is a prion disease of cattle which was first observed in Great Britain (GB) in 1986. Throughout the subsequent BSE epidemic, cases identified by passive surveillance have shown consistent histopathological, immunohistochemical, biochemical and biological properties. However, since the start of active surveillance in 2001, across Europe and elsewhere, approximately 67 cases with different biochemical characteristics have been identified by Western blotting (WB). These cases fall into two categories; 'H-type' (H-BSE) or 'L-type' (L-BSE), based on the relatively heavy (H-BSE) or light (L-BSE) mass of the unglycosylated band of the prion protein, as compared with WB against that obtained from classical BSE (C-BSE) cases. Here we report the detection and confirmation of the first four L-BSE cases by active surveillance in GB, two of which were born after the reinforced feed ban of 1996 (BARB cases). These four L-BSE cases were found in relatively old cattle (age range; 11-21 years old) and the carcases did not enter the human food chain or animal feed chains.

Experimental bovine spongiform encephalopathy: detection of PrP(Sc) in the small intestine relative to exposure dose and age.

European regulations for the control of bovine spongiform encephalopathy (BSE) decree destruction of the intestines from slaughtered cattle, therefore producers have been obliged to import beef casings from countries with a negligible BSE risk. This study applies immunohistochemical and biochemical approaches to investigate the occurrence and distribution of disease-associated prion protein (PrP(Sc)) in the duodenum, jejunum and ileum of cattle orally exposed to a 1 g or 100 g dose of a titrated BSE brainstem homogenate. Samples were derived from animals at various times post exposure. Lymphoid follicles were counted and the frequency of affected follicles recorded. No PrP(Sc) was detected in the duodenum or jejunum of animals exposed to a 1 g dose or in the duodenum of animals receiving a 100 g dose. PrP(Sc) was detected in the lymphoid tissue of the ileum of 1/98 (1.0%) animals receiving the 1 g dose and in the jejunum and ileum of 8/58 (13.8%) and 45/99 (45.5%), respectively, of animals receiving the 100 g dose. The frequency of PrP(Sc)- positive follicles was less than 1.5% per case and biochemical tests appeared less sensitive than immunohistochemistry. The probability of detecting lymphoid follicles in the ileum declined with age and for the 100 g exposure the proportion of positive follicles increased, while the proportion of positive animals decreased with age. Detection of PrP(Sc) in intestinal neural tissue was rare. The results suggest that the jejunum and duodenum of BSE-infected cattle contain considerably less BSE infectivity than the ileum, irrespective of exposure dose. In animals receiving the low exposure dose, as in most natural cases of BSE, the rarity of PrP(Sc) detection compared with high-dose exposure, suggests a very low BSE risk from food products containing the jejunum and duodenum of cattle slaughtered for human consumption.

Bovine spongiform encephalopathy: investigation of phenotypic variation among passive surveillance cases.

Bovine spongiform encephalopathy (BSE) is a prion disease of domesticated cattle, first identified in Great Britain (GB) in 1986. The disease has been characterized by histopathological, immunohistochemical, biochemical and biological properties, which have shown a consistent disease phenotype among cases obtained by passive surveillance. With the advent of active surveillance in 2001, immunological tests for detection of the prion protein revealed some cases with different biochemical characteristics and, in certain instances, differences in pathology that have indicated variant phenotypes and the possibility of agent strain variation. This study examines a case set of 523 bovine brains derived from archived material identified through passive surveillance in GB. All cases conformed to the phenotype of classical BSE (BSE-C) by histopathological, immunohistochemical and biochemical approaches. The analyses consolidated an understanding of BSE-C and, by western blotting, confirmed differentiation from the known atypical BSE cases which exhibit higher or lower molecular masses than BSE-C (BSE-H and BSE-L respectively).

Two unusual bovine spongiform encephalopathy cases detected in Great Britain.

Bovine spongiform encephalopathy (BSE) was first identified in Great Britain (GB) in 1986 and was subsequently detected in many other countries, worldwide. A decade after the start of the bovine epidemic, the first cases of new variant Creutzfeldt-Jakob disease (vCJD) in humans were linked to probable ingestion of BSE infected tissue, highlighting a new zoonotic disease. An abnormal protease-resistant protein (PrP(res)) in a diseased subject, derived from a post-translational change of a normal host cellular membrane protein (PrP(c)), is a reliable disease marker for the whole group of neurodegenerative transmissible spongiform encephalopathies (TSEs). Immunology-based techniques, such as Western immunoblotting, have previously indicated that BSE cases all give a uniform molecular profile for PrP(res). Periodic lesion profiling of the spongiform change throughout different brain regions of infected mice and cattle has also indicated a single agent for BSE. However, in 2001 rapid testing for PrP(res) was introduced for the active surveillance of ruminants within Europe, and approximately 40 BSE cases have now been recognized that differ in their molecular profiles from those typically found. These unusual BSE cases have been detected in several European countries, and in Japan and the USA. At present, the cases appear as two distinct types based on the molecular mass (Mm) of the unglycosylated PrP(res) protein band relative to that of classical BSE. One type is of a higher Mm (H-type) and the other shows a lower Mm (L-type). Transmission studies in mice have shown that both H-type and L-type BSE have biological characteristics that are different from those of the classical BSE agent. This study describes the prion protein (PRNP) genotype and molecular profiles of the first two cases of H-type BSE detected in GB in comparison with those obtained for classical BSE, scrapie in sheep from GB and a control H-type BSE case from France.

A disattenuated correlation estimate when variables are measured with error: illustration estimating cross-platform correlations.

Previous cross-platform reproducibility studies have compared consistency of intensities as well as consistency of fold changes across different platforms using Pearson's correlation coefficient. In this study, we propose the use of measurement error models for estimating gene-specific correlations. Additionally, gene-specific reliability estimates are shown to be useful in prioritizing clones for sequence verification rather than selecting clones using a simple random sample. The proposed 'disattenuated' correlation may prove useful in a wide variety of studies when both X and Y are measured with error, such as in confirmation studies of microarray gene expression values, wherein more reliable laboratory assays such as real-time polymerase chain reaction are used.

Estimating the temporal relationship between PrPSc detection and incubation period in experimental bovine spongiform encephalopathy of cattle.

This study examines tissues from sequential-kill, time-course pathogenesis studies to refine estimates of the age at which disease-specific PrP (PrP(Sc)) can first be detected in the central nervous system (CNS) and related peripheral nervous system ganglia of cattle incubating bovine spongiform encephalopathy (BSE). Such estimates are important for risk assessments of the age at which these tissues should be removed from cattle at slaughter to prevent human and animal exposure to BSE infection. Tissues were examined from cattle dosed orally with 100 or 1 g BSE-infected brain. Incubation period data for the doses were obtained from attack rate and the sequential-kill studies. A statistical model, fitted by maximum likelihood, accounted for the differences in the lognormal incubation period and the logistic probability of infection between different dose groups. Initial detection of PrP(Sc) during incubation was invariably in the brainstem and the earliest was at 30 and 44 months post-exposure for the 100 g- and 1 g-dosed sequential-kill study groups, respectively. The point at which PrP(Sc) in 50 % of the animals would be detected by immunohistochemistry applied to medulla-obex was estimated at 9.6 and 1.7 months before clinical onset for the 100 g- and 1 g-dosed cattle, respectively, with a low probability of detection in any of the tissues examined at more than 12 months before clinical onset. PrP(Sc) was detected inconsistently in dorsal root ganglia, concurrent with or after detection in CNS, and not at all in certain sympathetic nervous system ganglia.

Transportation of prion protein across the intestinal mucosa of scrapie-susceptible and scrapie-resistant sheep.

To determine the mechanisms of intestinal transport of infection, and early pathogenesis, of sheep scrapie, isolated gut-loops were inoculated to ensure that significant concentrations of scrapie agent would come into direct contact with the relevant ileal structures (epithelial, lymphoreticular, and nervous). Gut loops were inoculated with a scrapie brain pool homogenate or normal brain or sucrose solution. After surgery, animals were necropsied at time points ranging from 15 min to 1 month and at clinical end point. Inoculum-associated prion protein (PrP) was detected by immunohistochemistry in villous lacteals and in sub-mucosal lymphatics from 15 min to 3.5 h post-challenge. It was also detected in association with dendritic-like cells in the draining lymph nodes at up to 24 h post-challenge. Replication of infection, as demonstrated by the accumulation of disease-associated forms of PrP in Peyer's patches, was detected at 30 days and sheep developed clinical signs of scrapie at 18-22 months post-challenge. These results indicate discrepancies between the routes of transportation of PrP from the inoculum and sites of de novo-generated disease-associated PrP subsequent to scrapie agent replication. When samples of homogenized inoculum were incubated with alimentary tract fluids in vitro, only trace amounts of protease-resistant PrP could be detected by western blotting, suggesting that the majority of both normal and abnormal PrP within the inoculum is readily digested by alimentary fluids.

Postmortem diagnosis of preclinical and clinical scrapie in sheep by the detection of disease-associated PrP in their rectal mucosa.

Samples of tissue from the central nervous system (cns), the lymphoreticular system (lrs) and the rectal mucosa of a large number of scrapie-exposed sheep, with and without signs of clinical disease, were examined immunohistochemically for evidence of disease-associated prion protein (PrP(d)). The rectal mucosa has received almost no attention so far in scrapie diagnosis, despite its abundant rectoanal mucosa-associated lymphoid tissue, and its accessibility. The scrapie-confirmed cases included 244 with clinical disease, of which 237 (97.1 per cent) were positive in the rectal mucosa, and 121 apparently healthy sheep, of which 104 (86 per cent) were positive in the rectal mucosa. PrP(d) was detected in 86.4 to 91.5 per cent of the other lrs tissues of the healthy sheep examined and in 77.7 per cent of their cns tissues. The stage of infection, therefore, affected the probability of a positive result in the rectal mucosa, whereas the breed, PrP genotype, age and sex had little or no independent effect. Accumulations of PrP(d) were observed in the rectal mucosa and other lrs tissues of vrq/arr sheep with preclinical and clinical scrapie, albeit with a lower frequency and magnitude than in sheep of other PrP genotypes. Western immunoblotting analyses of samples of rectal mucosa gave the characteristic PrP glycoprofile, with a sensitivity similar to that of immunohistochemistry.

Preliminary observations on the experimental transmission of scrapie to elk (Cervus elaphus nelsoni) by intracerebral inoculation.

To determine the transmissibility of scrapie to Rocky Mountain elk (Cervus elaphus nelsoni), six elk calves were inoculated intracerebrally with brain suspension from sheep naturally affected with scrapie. One elk developed a brain abscess and was euthanatized at 7 weeks postinoculation (PI), and two others died at 6 and 15 months PI because of physical injuries. At 25 and 35 months PI, two other elk died after brief terminal neurologic episodes. Necropsy of these revealed moderate weight loss but no other gross lesions. Microscopically, characteristic lesions of spongiform encephalopathy were seen throughout the brains and the spinal cords, and in both cases these tissues were positive for PrP(res) by immunohistochemistry. Brains of both animals were positive for PrP(res) by western blot and for scrapie-associated fibrils (SAFs) by negative stain electron microscopy. PrP(res) and SAFs were not detected in the three elk that died or were euthanatized because of coincidental causes. Over 3.5 years after initiation of this experiment, the one remaining inoculated elk and two uninoculated (control) elk are alive and apparently healthy. These preliminary findings demonstrate that 1) sheep scrapie agent can be transmitted to elk by intracerebral inoculation; 2) the infection can result in severe, widely distributed spongiform change and accumulations of PrP(res) in the central nervous system (CNS); and 3) based on the examination of a limited number of CNS sections from two cases, this condition cannot be distinguished from chronic wasting disease with currently available diagnostic techniques.

Occurrence and distribution of infection-specific PrP in tissues of clinical scrapie cases and cull sheep from scrapie-affected farms in Shetland.

The prion protein (PrP) genotypes of all cull sheep originating from four scrapie-affected farms in Shetland in 1998-1999 were determined and a representative sample of the different genotypes was selected for necropsy. Samples of brain and selected viscera were removed from 159 such sheep aged 2-11 years. These samples were examined immunohistochemically and by Western blotting for infection-specific forms of PrP. None of the sheep bearing the following genotypes showed any evidence of PrP accumulation in brain, intestine, selected lymph nodes or the cranial mesenteric ganglia: ARQ/ARQ (n = 41), ARQ/ARH (n = 12), ARH/ARH (n = 2), ARQ/ARR (n = 24), ARR/ARR (n= 2). In five of 71 sheep bearing a single VRQ allele, PrP accumulation was detected immunohistochemically in viscera or brain, or both. These results suggested that only a small proportion of susceptible sheep showed evidence of infection (accumulation of PrP) on the farms studied, and that even sheep of the most susceptible genotype (VRQ/VRQ) did not invariably develop disease in an infected environment. Furthermore, there was no evidence that, in sheep of semi-resistant or fully resistant genotypes, infection could be sequestered within the lymphoreticular system or peripheral nervous system and thereby provide a possible "carrier" source of infection. Rather, the data suggested that some sheep, possibly because they had been exposed to a relatively low infective dose, became infected and accumulated the infective agent over a protracted pre-clinical phase of the disease. Such sheep might be potentially infective for many years. In two VRQ/ARR genotype sheep, PrP was confined to the brain. Infection-specific PrP was also confined to the brain in two of 24 clinical cases of VRQ/ARQ scrapie. Thus, direct neuroinvasion, apparently without a prior phase of replication in the lymphoreticular system, occurred in a proportion of VRQ/ARQ sheep. Possibly it may occur in all sheep of the VRQ/ARR genotype. The factors responsible for direct neuroinvasion are not understood. However, it cannot be attributed to genotype alone.

Evaluation of the effects of controlled autolysis on the immunodetection of PrP(Sc) by immunoblotting and immunohistochemistry from natural cases of scrapie and BSE.

Seventeen clinically suspect scrapie sheep, and twelve suspected BSE-affected cattle were confirmed using routine histopathological examination by the detection of characteristic spongiform change in the medulla brain region taken at the level of the obex. Three sheep and four cows acquired as controls showed no spongiform change. Five aliquots of brain tissue from each of four brain regions were taken (cerebellum, medulla, frontal cerebral cortex and occipital cerebral cortex) from each of the 36 animals. One aliquot was frozen at -70 degrees C, the others were subjected to one of four autolysis regimes at 3 or 7 days at 25 degrees C or 37 degrees C. All samples were tested by Western immunoblotting for detection of PrP(Sc) using the Prionics - Check test (Prionics AG, Zurich, Switzerland). Further samples of medulla from 15 suspect scrapie cases, 10 healthy sheep, 13 suspect BSE cows and 5 healthy cows, were taken adjacent to the obex, and subjected to autolysis at 37 degrees C for 6, 12, 24 and 48 hours before being fixed in 10 per cent formal saline and subsequently examined by a routine immunohistochemical technique for detection of PrP(Sc) protein. The abnormal protein could not be detected in any of the control animals by either technique. PrP(Sc) could be detected by Western immunoblotting in at least one brain area from all the positive animals after autolysis for 7 days at 37 degrees C. The protein could be detected by immunohistochemistry in all cases which were positive by histopathological examination using all autolysis conditions. From the results of this study it is concluded that autolysis does not significantly compromise the diagnosis of scrapie or BSE by either of these diagnostic methods.