Search

Clear-air turbulence (CAT) has a large impact on the aviation sector. Our current understanding of how CAT may increase with climate change in future is largely based on simulations from CMIP3 and CMIP5 global climate models (GCMs). However, these models have now been superseded by high-resolution CMIP6 GCMs, which for the first time have grid lengths at which individual turbulence patches may start to be resolved. Here we use a multi-model approach to quantify projected moderate CAT changes over the North Atlantic using CMIP6 models. The influence of the model resolution on CAT projections is analysed. Twenty-one CAT diagnostics are used, in order to represent uncertainties in CAT production mechanisms. Each diagnostic responds differently in time, but the majority display an increase in moderate CAT between 1950 and 2050. Although winter is historically the most turbulent season, there is strong multi-model agreement that autumn and summer will have the greatest overall relative increase in CAT frequency. By 2050, summers are projected to become as turbulent as 1950 winters and autumns. The global-mean seasonal near-surface temperature is used as a comparative metric. For every 1 °C of global near-surface warming, autumn, winter, spring, and summer are projected to have an average of 14%, 9%, 9%, and 14% more moderate CAT, respectively. Our results confirm that the aviation sector should prepare for a more turbulent future.

BACKGROUND Children with neurodevelopmental disorders have a high risk of sleep disturbances, with insomnia being the most common sleep disorder (i.e., chronic and frequent difficulties with going and staying asleep). Insomnia adversely affects the well-being of these children and their caregivers. Pediatric sleep experts recommend behavioral interventions as the first-line treatment option for children. Better Nights, Better Days for Children with Neurodevelopmental Disorders (BNBD-NDD) is a five-session eHealth behavioural intervention delivered to parents to improve outcomes (e.g., Pediatric Quality of Life Inventory) for their children (4-12 years) with insomnia and who have a diagnosis of mild-to-moderate attention-deficit/hyperactivity disorder, autism spectrum disorder, cerebral palsy, and/or fetal alcohol spectrum disorder. If effective, BNBD-NDD can be a scalable intervention that provides value to an underserved population. OBJECTIVE This protocol outlines an economic evaluation conducted alongside the BNBD-NDD randomized controlled trial (RCT) that aims to assess its costs and effectiveness compared to usual care. METHODS The BNBD-NDD RCT evaluates the impacts of the intervention on children’s sleep and quality of life, as well as parent daytime functioning and psychosocial health. Parent participants were randomized to the BNBD-NDD treatment or to usual care. The economic evaluation assesses outcomes at baseline and 8 months later, which include the Pediatric Quality of Life Inventory (PedsQL) as the primary measure. Quality of life outcomes facilitates the comparison of competing interventions across different populations and medical conditions. Cost items include the BNBD-NDD intervention and parent-reported utilization of private and publicly funded resources for their children’s insomnia. The economic evaluation involves a reference-case cost-effectiveness analysis to examine the incremental cost of BNBD-NDD per unit(s) gain in the PedsQL from the family payer perspective and a cost-consequence analysis from a societal perspective. These analyses will be conducted over an 8-month time horizon. RESULTS The BNBD-NDD RCT data collection commenced in June 2019 and ended in April 2022. The RCT data are currently being analyzed, and data relevant to the economic analysis will be analyzed concurrently. CONCLUSIONS To our knowledge, this will be the first economic evaluation of an eHealth intervention for insomnia in children with neurodevelopmental disorders. This evaluation's findings can inform users and stakeholders regarding the costs and benefits of BNBD-NDD. CLINICALTRIAL ClinicalTrial.gov ID NCT02694003

Mental health problems are prevalent in autistic youth, but the underpinning mechanisms are not well explored. In neurotypical youth, stressful life events are an established risk factor for mental health problems. This study tested longitudinal bidirectional associations between family-level stressful life events and mental health problems and whether these were moderated by cognitive flexibility, in a cohort of autistic children ( N = 247). Family-stressful life events, assessed using the parent-reported Family Inventory of Life Events and Changes, and mental health problems, assessed using the teacher-reported Child Behavior Checklist Internalizing and Externalizing Symptoms subscales, were measured at multiple points between 7 and 11 years. Analyses showed no significant pathways from internalizing or externalizing symptoms to family-stressful life events or from family-stressful life events to internalizing or externalizing symptoms. There was some evidence of moderation by cognitive flexibility; the family-stressful life events to internalizing symptoms pathway was non-significant in the group with typical shifting ability but significant in the group with clinically significant shifting problems. Information about family-level stressful life event exposure and cognitive flexibility may be helpful in identifying autistic youth who may be at higher risk of developing mental health problems. Established risk factors for mental health problems in neurotypical populations are relevant for understanding mental health in autistic youth. Lay abstract Experiencing stressful life events, such as a parent having had serious illness, parental divorce, bullying and victimization, is known to increase risk for mental health difficulties in neurotypical children. However, few studies have looked at whether stressful life events have a similar impact in autistic youth and if any individual characteristics may moderate the impact of said life events. In this study, we tested whether in autistic children aged 7–11 years, exposure to family-level stressful life events predicted later mental health symptoms (and vice versa). We also tested whether associations between stressful life events and mental health symptoms differed depending on the child’s level of cognitive flexibility. We found stressful life events only predicted internalizing symptoms (such as anxiety and depression) in children with clinically significant difficulties in cognitive flexibility (as rated by their parents). Mental health symptoms did not predict future exposure to stressful life events. Results suggest that information about exposure to stressful life events and cognitive inflexibility may be helpful in identifying autistic children who may be at risk of developing anxiety and depression symptoms.

This session will provide ‘an introduction to mitigating solutions’ such as carbon sources and sinks, heat sources and sinks, and reducing our individual carbon footprints.

Analyzing the mutational load of driver mutations in melanoma could provide valuable information regarding its progression. We aimed at analyzing the heterogeneity of mutational load of BRAF V600E in biopsies of melanoma patients of different stages, and investigating its potential as a prognosis factor. Mutational load of BRAF V600E was analyzed by digital PCR in 78 biopsies of melanoma patients of different stages and 10 nevi. The BRAF V600E load was compared among biopsies of different stages. Results showed a great variability in the load of V600E (0%-81%). Interestingly, we observed a significant difference in the load of V600E between the early and late melanoma stages, in the sense of an inverse correlation between BRAF V600E mutational load and melanoma progression. In addition, a machine learning approach showed that the mutational load of BRAF V600E could be a good predictor of metastasis in stage II patients. Our results suggest that BRAF V600E is a promising biomarker of prognosis in stage II patients. This research was supported by the Basque Government (grants ELKARTEK-KK2016-036 and KK2017-041 to MDB, grant IT1138-16 to SA and predoctoral fellowship PRE_2014_1_419 to AS), and by the University of the Basque Country (UPV/EHU) (grant GIU17/066). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Background: Copy Number Variants (CNVs) contribute to a large fraction of genetic diversity and some of them have been reported to offer an evolutionary advantage.Aim: To identify CNVs in pigmentary loci that could contribute to human skin pigmentation diversity.Subjects and methods: This study assessed the existence of CNVs in every exon of candidate genes: TYR, TYRP1, DCT, MC1R and SLC24A5, using the Multiplex Amplifiable Probe Hybridization technique (MAPH). This study analysed a total of 99 DNA samples of unrelated individuals from different populations. Validation and further analysis in a larger Spanish sample were performed by RT-qPCR.Results: Five CNVs were identified by MAPH: DCT exons 4 and 8, TYR exon 1 and SLC24A5 exons 1 and 4. Real-time quantitative PCR (RT-qPCR) confirmed the CNV in exon 1 of SLC24A5. This study further analysed the 5′ promoter region of SLC24A5 and found another CNV in this region. However, no association was found between the CNV and the degree of pigmentation.Conclusion: Although the functional role of these structural variants in pigmentation should be the subject of future work, the results emphasize the need to consider all classes of variation (both SNPs and CNVs) when exploring the genetics of skin pigmentation.

The primary purpose of this study was to examine the underlying factor structure of the Parenting Stress Index-Short Form (PSI-SF) in a large cohort of parents of young children with autism spectrum disorder (ASD). A secondary goal was to examine relationships between PSI-SF factors and autism severity, child behavior problems, and parental mental health variables that have been shown to be related to parental stress in previous research. A confirmatory factor analysis (CFA) was used to examine the three-factor structure described in the PSI-SF manual [Abidin, 1995]: parental distress, parent-child dysfunctional interaction, and difficult child. Results of the CFA indicated that the three-factor structure was unacceptable when applied to the study sample. Thus, an exploratory factor analysis was conducted and suggested a six-factor model as the best alternative for the PSI-SF index. Spearman's correlations revealed significant positive correlations with moderate to large effect sizes between the revised PSI-SF factors and autism severity, externalizing and internalizing child behaviors, and an index of parent mental health. The revised factors represent more narrowly defined aspects of the three original subscales of the PSI-SF and might prove to be advantageous in both research and clinical applications. Autism Res 2011,4:336-346. © 2011 International Society for Autism Research, Wiley Periodicals, Inc.

Background/Aim:TP53 is an efficient central node in a signal transduction network that responds to minimize cancer. However, over 50% of tumors show some mutation in TP53. Thus, one might argue that this single central node network lacks robustness. Therefore, we wanted to investigate if natural selection has played a role in shaping the genomic region containing TP53. Methods: We have analyzed the HapMap data for evidence of selection using FST pairwise comparisons and the extended haplotype homozygosity test on a 200-kb region encompassing TP53. We have also resequenced 4 kb upstream TP53 in Europeans (including melanoma patients), Asians, Australian Aborigines and Africans. Results: Genetic hitchhiking by a linked, positively selected allele at the nearby gene WDR79 may be partly responsible for the sequence diversity profile of TP53. It can help explain why the TP53 Arg72 allele is the major allele in Europeans even when the alternative allele, 72Pro, has been reported to offer an increased longevity after disease. Conclusions: Despite the important role of TP53, a complex interplay with other evolutionary forces, which are extrinsic to TP53 function, may have driven the genetic diversity pattern of this locus, and, as a consequence, its structure and function.

Summary Background/Purpose The response to the damage provoked by exposure to UV radiation is mediated by melanocytes and a network of paracrine factors produced by keratinocytes, and it varies among individuals of different geographical origin and skin colour. The mechanisms underlying this differential response, however, have not been completely elucidated. Methods We characterized the differential behaviour of melanocytes (proliferation and differentiation/melanogenesis) from both dark- and light-skinned individuals in response to ultraviolet B (UVB) irradiation, cultured with and without keratinocyte-conditioned medium (KCM). ELISA assays and real-time quantitative PCR were used to assess the production of keratinocyte-derived factors. Results After UVB irradiation, dark melanocytes showed a decreased proliferation consistent with the highly differentiated state inferred by the increased dendricity of the cells and higher levels of melanogenic genes expression, whereas light melanocytes showed an increase in proliferation in accord with a less differentiated state and decreased melanogenesis levels. KCM induced melanogenesis in dark melanocytes after UVB irradiation, but not in light-pigmented melanocytes. Conclusion Proliferation and differentiation are coordinated in response to UVB. A lower proliferative rate and a higher differentiation state in dark melanocytes could account for more effective photoprotective mechanisms that would prevent from cell damage against UVB irradiation.

A search was made of the literature on behaviour in early treated phenylketonuria (PKU). Some 34 publications were selected for systematic review in order to answer the following questions: (1) does behaviour in early treated subjects with PKU differ from that in the general population?, (2) if so, do the differences show any consistent pattern?, matter in real life?, relate to intellectual status, phenylalanine (Phe) control or social factors? and (3) can behavioural problems be precipitated or reversed by changes in Phe control?. Eleven reports based on four studies of >20 subjects provided the most useful data. There was good evidence of differences between subjects with PKU and their unaffected peers in behaviour and perception of self. The pattern of results was consistent across nations and age groups (higher scores on emotional/neurotic items and lower scores on anti-social/aggressive items) and suggested that subjects with PKU are more prone to depression, anxiety, phobic tendencies, isolation from their peers and a less “masculine” self image. Features of attention deficit hyperactivity disorder and associations between behaviour problems and both lower IQ and a worse quality of Phe control were well documented in several studies.

A comprehensive gene expression analysis of human melanocytes was performed assessing the transcriptional profile of dark melanocytes (DM) and light melanocytes (LM) at basal conditions and after UV-B irradiation at different time points (6, 12 and 24h), and in culture with different keratinocyte-conditioned media (KCM+ and KCM−). The data, previously published in [1], have been deposited in NCBI's Gene Expression Omnibus (GEO accession number: GSE70280).

Elevated soluble IL-2 receptor (sIL-2R) and IL-6 serum concentrations have been reported as adverse prognostic factors in several types of cancer. In order to determine whether these factors are predictive of metastatic progression in melanoma, sIL-2R and IL-6 levels were measured in sera from 172 patients with melanoma and 60 in healthy controls. Mean sIL-2R values were significantly higher in the patients than in normal controls and the highest values were observed in those that developed metastasis during follow-up. However, no correlation was found with the stage of the disease. Serum IL-6 levels were found to be correlated with age and sex, but not correlated with sIL-2R levels. Statistical analysis was based on logistic and Cox regression models. The factors considered were age, sex, stage, disease-free interval and serum sIL-2R and IL-6 levels. The analysis showed that only the sIL-2R value is significantly linked to metastatic progression. This finding suggests that high serum levels of sIL-2R could be a predictive factor of metastatic progression in malignant melanoma.

In humans, the geographical apportionment of the coding diversity of the pigmentary locus melanocortin-1 receptor (MC1R) is, unusually, higher in Eurasians than in Africans. This atypical observation has been interpreted as the result of purifying selection due to functional constraint on MC1R in high UV-B radiation environments. By analyzing 3,142 human MC1R alleles from different regions of Spain in the context of additional haplotypic information from the 1000 Genomes (1000G) Project data, we show that purifying selection is also strong in southern Europe, but not so in northern Europe. Furthermore, we show that purifying and positive selection act simultaneously on MC1R. Thus, at least in Spain, regions at opposite ends of the incident UV-B radiation distribution show significantly different frequencies for the melanoma-risk allele V60L (a mutation also associated to red hair and fair skin and even blonde hair), with higher frequency of V60L at those regions of lower incident UV-B radiation. Besides, using the 1000G south European data, we show that the V60L haplogroup is also characterized by an extended haplotype homozygosity (EHH) pattern indicative of positive selection. We, thus, provide evidence for an adaptive value of human skin depigmentation in Europe and illustrate how an adaptive process can simultaneously help to maintain a disease-risk allele. In addition, our data support the hypothesis proposed by Jablonski and Chaplin (Human skin pigmentation as an adaptation to UVB radiation. Proc Natl Acad Sci U S A. 2010;107:8962-8968), which posits that habitation of middle latitudes involved the evolution of partially depigmented phenotypes that are still capable of suitable tanning. This works was supported by the former Spanish Ministerio de Ciencia e Innovación, project CGL2008-04066/BOS to S.A.; by the Dpt. Educacion, Universidades e Investigación of the Basque Government, project IT542-10; by program UFI11/09 by the University of the Basque Country, by "Programa de Investigacion Cientifica de la Universidad de La Laguna" (boc-a- 2010-255-7177), and by grants from the Health Institute “Carlos III” (FIS PI08/1383, FIS PI11/00623) to C.F. and co-financed by the European Regional Development Funds, “A way of making Europe” from the European Union. M.P.Y. was supported by a postdoctoral fellowship from Fundación Ramón Areces. We thank the Spanish Banco Nacional de AND (BNADN) (http://www.bancoadn.org/) for providing us with DNA samples from all over Spain. We also thank the Spanish Agencia Estatal de Meteorología (AEMET) (http://www.aemet.es/) for kindly providing us with the UV-B radiation data.

In this study, we analyzed interleukin-2 (IL-2) and IL-2 receptor (IL-2R) expression in murine B16F10 melanoma and studied the effect of recombinant IL-2 (rIL-2) on the proliferation of these cells. Flow cytometry analysis revealed the presence of the IL-2R alpha subunit in B16F10 melanoma, with a mean positivity rate of 30%. Using confocal microscopy, the expression of this chain could be visualized on the surface of B16F10 cells and in intracellular compartments when the cells were permeabilized with ethanol. In addition to the alpha subunit, the IL-2R beta subunit was also expressed in B16F10 cells as shown by reverse transcription and polymerase chain reaction analysis. The functionality of the IL-2R on B16F10 cells was shown by the fact that cell proliferation increased dose-dependently with the addition of rIL-2 to the culture medium. We also detected expression of the IL-2 gene in B16F10 cells. In Northern blot assays, a typical band of 0.9 kb corresponding to IL-2 mRNA was observed, although supernatants from B16F10 cultures had no detectable IL-2 activity. Furthermore, the addition of neutralizing antibody (anti-IL-2) to cell cultures had no effect on cell proliferation. From these results, we concluded that an IL-2 signalling system is present in murine B16F10 melanoma cells and that IL-2 favors B16F10 cell proliferation, suggesting a role for this cytokine in the tumoral activity of these cells.

Autism spectrum disorder (ASD) is characterized by notable phenotypic heterogeneity, which is often viewed as an obstacle to the study of its etiology, diagnosis, treatment, and prognosis. On the basis of empirical evidence, instead of three binary categories, the upcoming edition of the DSM 5 will use two dimensions - social communication deficits (SCD) and fixated interests and repetitive behaviors (FIRB) - for the ASD diagnostic criteria. Building on this proposed DSM 5 model, it would be useful to consider whether empirical data on the SCD and FIRB dimensions can be used within the novel methodological framework of Factor Mixture Modeling (FMM) to stratify children with ASD into more homogeneous subgroups.The study sample consisted of 391 newly diagnosed children (mean age 38.3 months; 330 males) with ASD. To derive subgroups, data from the Autism Diagnostic Interview-Revised indexing SCD and FIRB were used in FMM; FMM allows the examination of continuous dimensions and latent classes (i.e., categories) using both factor analysis (FA) and latent class analysis (LCA) as part of a single analytic framework.Competing LCA, FA, and FMM models were fit to the data. On the basis of a set of goodness-of-fit criteria, a 'two-factor/three-class' factor mixture model provided the overall best fit to the data. This model describes ASD using three subgroups/classes (Class 1: 34%, Class 2: 10%, Class 3: 56% of the sample) based on differential severity gradients on the SCD and FIRB symptom dimensions. In addition to having different symptom severity levels, children from these subgroups were diagnosed at different ages and were functioning at different adaptive, language, and cognitive levels.Study findings suggest that the two symptom dimensions of SCD and FIRB proposed for the DSM 5 can be used in FMM to stratify children with ASD empirically into three relatively homogeneous subgroups.

Maintaining B16F10 tumor cells in stirring culture for 48 h leads to an increase in lung and liver colonizing capacity in comparison with cells in adherent culture. Parallel to the increased metastatic capacity, we have observed a decrease in the proliferative rate of tumor cells (as the percentage of proliferating cell nuclear antigen-positive cells) and an increase in the population of tumor cells expressing Ia antigen. These results are not exclusive to B16F10 cells, since the same results were obtained when we analyzed 3LL cells maintained in identical culture conditions. In all the tumor lines tested, we found an association between the nonproliferating and the Ia-positive cell populations. We induced Ia expression by treating B16F10 cells in adherent culture with the lectin concanavalin A and again, coincident with an increase in metastatic capacity, we found the same association between the two parameters analyzed--nonproliferating state and Ia antigen expression. In addition, it was found that B16F10 cells induce lymphocytic proliferation, and a direct relationship was established between the number of Ia+ cells and lymphocytic proliferation.

Maximizing measurement accuracy is an important aim in child development assessment and research. Parents are essential informants in the diagnostic process, and past research suggests that certain parental characteristics may influence how they report information about their children. This has not been studied in autism spectrum disorders (ASD) to date. We aimed, therefore, to investigate the possible effect that maternal depression might have on a mother's reports of her child's ASD behaviors. Using structural equation modeling, we disaggregated shared from unique variation in the association between latent variable measures of maternal depression and ASD behaviors.Data were obtained from a study of preschoolers aged 2-4 newly diagnosed with ASD (n = 214). Information from a parent questionnaire, a semi-structured parent interview, and a semi-structured observational assessment was used to develop a latent variable measure of child ASD behaviors. Mothers reported on their own depression symptoms. We first modeled the covariance between maternal depression and child ASD behavior. Then, to quantify unique variation, we added covariance terms between maternal depression and the residual variation associated with the individual measures of child ASD behaviors.The model demonstrated excellent fit to the underlying data. Maternal self-report of depression symptoms exhibited a significant association with the unique variance of the questionnaire report but not with the latent variable measure of child ASD behavior. A gradient pattern of association was demonstrated between maternal depression and the unique variance of the ASD measures: most strongly for the maternal questionnaire report, more weakly for the maternal semi-structured interview, and to a trivial extent for the observational interview.Parental depression may influence reporting of ASD behaviors in preschoolers. Shared method effects may also contribute to bias. This finding highlights the importance of obtaining multimethod reports of child ASD symptoms.

The NeuroDevNet Autism Spectrum Disorder Demonstration Project interfaces at many levels with the network's research themes and priorities. Our interdisciplinary team aims to improve understanding of genetic factors underlying vulnerability to autism spectrum disorders (ASDs) to develop better diagnostic strategies and, ultimately, to pinpoint molecular pathways relevant to developing biologically based treatments. Linking our existing longitudinal ASD cohorts with both genetics and neuroimaging studies will provide, for the first time, integrated data on how the genetic variation influences brain and behavioral development in ASD. Importantly, as our science progresses and we translate this information to the health care system, we will also educate policy makers, media, and business, so an informed society is prepared to capitalize on new genomic advances and effectively integrate these into health services for the broader community. We believe that this research has the potential to transform assessment and care for individuals with ASD.

Students often have an oversimplified view of biological facts, which may hinder subsequent understanding when conceptual complexity gives rise to cognitive conflicts. To avoid this situation here, we present a PBL approach for the analysis of Ehlers-Danlos syndrome (EDS), which integrates a variety of topics in cell biology, genetics, and molecular biology, and it is used to illustrate the inherent complexities in some classical biological concepts. Students of two different courses analyze phenotypic, cellular, and molecular characteristics of EDS. Effect of mutations on collagen synthesis on collagen genes' expression and regulation or on connective tissues is reviewed and discussed. Information retrieval is used to develop students' skills in web-based molecular biology tools. Student interest and motivation is increased with the development of diagnostic protocols for a tissue biopsy and for an EDS causing mutation. Expected learning outcomes after completion of the project are also presented.

Problem Based Learning (PBL) makes use of real-life scenarios to stimulate students' prior knowledge and to provide a meaningful context that is also related to the student's future professional work. In this article, Paternity testing is presented using a PBL approach that involves a combination of classroom, laboratory, and out-of-class activities: in relation to a fictitious newborn found on the Campus, students design a PCR based protocol to determine their own genotype for two markers. Pooled class genotypes serve to calculate allelic frequencies and to assess Hardy-Weinberg equilibrium. Individual results are also evaluated for possible paternity. The goals of the activity and how each step in the process relates to learning outcomes are presented. Classroom discussions, group discussions, tutorial sessions, wiki sites, laboratory activities, and individual reports sum up the situations, in which the students' process of learning and learning outcomes can be evaluated.

This study examined the phenotypic overlap between core diagnostic features and emotional/behavioral problems in a sample of 335 preschool children with autism spectrum disorder (ASD). Results from principal component analysis (2 components; 49.70% variance explained) suggested substantial phenotypic overlap between core diagnostic features and emotional/behavioral problems. Component I, Emotional Behavioral Repetitive Problems, was independent of the children's intellectual, adaptive functioning, and structural language abilities. Component II, Social Communication Deficits, was negatively related to the children's intellectual, adaptive functioning, and structural language abilities. Both components were positively related to parental stress. This exploratory study contributes to our understanding of the ASD phenotype and provides further support for including emotional/behavioral problems as part of the clinical characterization of children with ASD.

Following the intrasplenic injection of B16F10 melanoma cells into mice, at first single cells, and later multicellular tumor foci were observed at different times in the liver. Cell numbers and tumor volumes were determined over the next 12 days, by confocal microscopy of thick liver sections. Fifteen minutes after injection, approximately 20% of the melanoma cells were identified in the liver microvasculature; after 48 hr, only 0.68% of these retained morphologic integrity; by 5 days only 0.13% of the originally detected cells incorporated BUdR; and, by 12 days, these subsequently grew into tumor nodules. Tumor volume changes with time were not exponential and, following a non-replicative period during the first 2½ days, the volume doubling times increased from approximately 8 to 39 hr at 12 days. BUdR incorporation indicated that this was probably due to a diminishing proliferative fraction in the cancer-cell population. When animals were killed at 12 days, tumor foci were centered on the liver sinusoids and appeared to represent expansive growth of arrested cells, with no evidence of parenchymal invasion by migrating cancer cells, in spite of the absence of a subendothelial basement membrane. Our direct observations indicate that, in this model system, the post-delivery phase of hepatic colonization is characterized by high levels of inefficiency with respect to cancer-cell survival, growth and extravasation. © 1992 Wiley-Liss, Inc.

TP53 is an efficient central node in a signal transduction network that responds to minimize cancer. However, over 50% of tumors show some mutation in TP53. Thus, one might argue that this single central node network lacks robustness. Therefore, we wanted to investigate if natural selection has played a role in shaping the genomic region containing TP53.We have analyzed the HapMap data for evidence of selection using F(ST) pairwise comparisons and the extended haplotype homozygosity test on a 200-kb region encompassing TP53. We have also resequenced 4 kb upstream TP53 in Europeans (including melanoma patients), Asians, Australian Aborigines and Africans.Genetic hitchhiking by a linked, positively selected allele at the nearby gene WDR79 may be partly responsible for the sequence diversity profile of TP53. It can help explain why the TP53 Arg72 allele is the major allele in Europeans even when the alternative allele, 72Pro, has been reported to offer an increased longevity after disease.Despite the important role of TP53, a complex interplay with other evolutionary forces, which are extrinsic to TP53 function, may have driven the genetic diversity pattern of this locus, and, as a consequence, its structure and function.

We had previously shown that murine B16F10 melanoma cells express the receptor for IL-2, transcribe the gene for IL-2 and respond to its factor by increasing their proliferation. In the present work we have investigated the effect of in vitro IL-2 treatment on the metastatic ability of B16F10 cells. In vivo experiments showed that the metastatic colonization of the liver was notably higher after intrasplenic inoculation of IL-2-treated cells. However, no change was observed when cells were intravenously inoculated. In vitro, cells became more resistant to NK lysis although the cytometric analysis of class 1 MHC molecules revealed a decrease in H-2Kb expression. In contrast IL-2 induced a two fold increment in the expression of la antigen. On the other hand slot-blot analysis showed that IL-2 gene expression could be upregulated, however no free IL-2 was released into the culture medium of B16F10 cells. We conclude that IL-2 increases the ability of B16F10 cells to metastase to the liver. The increase in the resistance to NK activity and in la antigen expression could be involved in the mechanisms underlying this effect.

Fluorescent probes were used to detect BUdR-labelled B16F10 and M5076 cancer cells delivered to the livers of mice via intrasplenic injection. In liver sections stained for succinic dehydrogenase, which permits the periportal, acinar zone 1 to be distinguished from the pericentral zone 3, counts were made of the zonal distribution of fluorescent, intact cancer cells and, by default, the numbers of "lost" cells. Very few intact cancer cells leave the liver from the single bolus of the intrasplenic injection, and even fewer of these generate pulmonary lesions; therefore, within the time limits of these experiments, the liver is virtually a closed system. A dynamic view of intrahepatic cancer-cell traffic with respect to zones 1 (periportal) and 3 (pericentral) was obtained from static measurements of cell densities at different times after intrasplenic injection, by means of Markov chain probability analysis. This indicated that, during the first hour after arrival in zone 1 of the liver sinusoids, there is a 10% probability of a B16F10 cell remaining intact in zone 1, an 89% probability of cell death in zone 1 and only a 1% probability of the cell passing into zone 3. During the same period, there is a 77% probability of an M5076 cell remaining intact in zone 1, a 21% probability of death, and a 2% probability of relocation to zone 3. In both cell types, very few cells were lost from zone 3. Further proportional death in zone 1 diminished over the next 23 hr, concomitant with an increased proportion of cell death in zone 3. Our results indicate that, although there is considerable variation between the 2 cell types studied here, most (B16) or many (M5076) of these cancer cells entering the liver via the portal vein die within 1 hr in zone 1 of liver lobules. In addition, very few of the cells delivered to zone 1 travel along the sinusoids to zone 3, and few of these reach the lungs in a viable state.