Control of Parasitophorous Vacuole Expansion by LYST/Beige Restricts the Intracellular Growth of Leishmania amazonensis

The intracellular protozoan Leishmania replicates in parasitophorous vacuoles (PV) that share many features with late endosomes/lysosomes. L. amazonensis PVs expand markedly during infections, but the impact of PV size on parasite intracellular survival is still unknown. Here we show that host cells infected with L. amazonensis upregulate transcription of LYST/Beige, which was previously shown to regulate lysosome size. Mutations in LYST/Beige caused further PV expansion and enhanced L. amazonensis replication. In contrast, LYST/Beige overexpression led to small PVs that did not sustain parasite growth. Treatment of LYST/Beige over-expressing cells with vacuolin-1 reversed this phenotype, expanding PVs and promoting parasite growth. The opposite was seen with E-64d, which reduced PV size in LYST-Beige mutant cells and inhibited L. amazonensis replication. Enlarged PVs appear to protect parasites from oxidative damage, since inhibition of nitric oxide synthase had no effect on L. amazonensis viability within large PVs, but enhanced their growth within LYST/Beige-induced small PVs. Thus, the upregulation of LYST/Beige in infected cells functions as a host innate response to limit parasite growth, by reducing PV volume and inhibiting intracellular survival

Empirical Bayesian Mixture Models for Medical Image Translation

Automatically generating one medical imaging modality from another is known as medical image translation, and has numerous interesting applications. This paper presents an interpretable generative modelling approach to medical image translation. By allowing a common model for group-wise normalisation and segmentation of brain scans to handle missing data, the model allows for predicting entirely missing modalities from one, or a few, MR contrasts. Furthermore, the model can be trained on a fairly small number of subjects. The proposed model is validated on three clinically relevant scenarios. Results appear promising and show that a principled, probabilistic model of the relationship between multi-channel signal intensities can be used to infer missing modalities -- both MR contrasts and CT images.Comment: Accepted to the Simulation and Synthesis in Medical Imaging (SASHIMI) workshop at MICCAI 201

Predicting the response to sorafenib in hepatocellular carcinoma: where is the evidence for phosphorylated extracellular signaling-regulated kinase (pERK)?

The approval of sorafenib and active development of many other molecularly targeted agents in hepatocellular carcinoma (HCC) have presented a challenge to understand the mechanism of action of sorafenib and identify predictive biomarkers to select patients more likely to benefit from sorafenib. The preclinical study by Zhang and celleagues published this month in BMC Medicine provides preliminary evidence that baseline phosphorylated extracellular signaling-regulated kinase (pERK) may be a relevant marker to reflect the level of constitutive activation of the RAF/mitogen-activated protein kinase kinase (MEK)/ERK signaling pathway and has the potential value in predicting response to sorafenib. The clinical data from the initial single arm phase II study and preliminary report from the randomized phase III study also suggest the correlation of baseline archived tumor pERK levels and time to tumor progression in HCC patients. Whether baseline pERK will prove to be a useful predictive biomarker of response and clinical benefits for sorafenib in HCC will need to be validated in future large prospective studies

inVestIgating the pSychologIcal and ecONomic impAct of cataRact surgerY in Vietnam: The VISIONARY observational study protocol

<p>Abstract</p> <p>Background</p> <p>Visual impairment caused by cataracts not only affects an individual's quality of life but can also have a profound impact on other important psychological factors and on the economic circumstances of individuals and their households. Cataract surgery is an effective intervention to restore vision and is also associated with other positive consequences including improvements in quality of life, economic and psychological outcomes. While there has been an increase in the number and quality of cataract surgeries performed in Vietnam, the programs currently in place are still unable to meet the existing demand and need for surgery. Data on both the cost-effectiveness of cataract surgery and the economic and psychological impact of untreated cataract in this setting is lacking.</p> <p>Methods/Design</p> <p>This study, investigating the psychological and economic impact of cataract surgery in Vietnam (VISIONARY), will recruit and interview a sample of adults (18 years or over) who are referred for cataract surgery by one of the following sites and their outreach programs: Hue Eye Hospital; Thai Binh Eye Hospital; Binh Dinh Department of Health Eye Hospital and the Vinh Long Department of Health Social Disease Centre. All participants (those who have cataract surgery and those who do not have surgery) will be followed up at six and 12 months.</p> <p>Discussion</p> <p>This study is designed to examine the impact of low vision on household economic circumstances and psychological outcomes as well as to investigate the effectiveness and cost-effectiveness of cataract surgery in Vietnam. It will help to inform international and national non-government organisations working in the country and local policy-makers on priorities for further investment in eye-health services in this setting and their relevance to broader economic development goals.</p

Organic-Inorganic Nanostructure Architecture via Directly Capping Fullerenes onto Quantum Dots

A new form of fullerene-capped CdSe nanoparticles (PCBA-capped CdSe NPs), using carboxylate ligands with [60] fullerene capping groups that provides an effective synthetic methodology to attach fullerenes noncovalently to CdSe, is presented for usage in nanotechnology and photoelectric fields. Interestingly, either the internal charge transfer or the energy transfer in the hybrid material contributes to photoluminescence (PL) quenching of the CdSe moieties.open2

Active Chromatin Marks Are Retained on X Chromosomes Lacking Gene or Repeat Silencing Despite XIST/Xist Expression in Somatic Cell Hybrids

X-chromosome inactivation occurs early in mammalian development and results in the inactive X chromosome acquiring numerous hallmarks of heterochromatin. While XIST is a key player in the inactivation process, the method of action of this ncRNA is yet to be determined.To assess which features of heterochromatin may be directly recruited by the expression and localization of the XIST RNA we have analyzed a mouse/human somatic cell hybrid in which expression of human and mouse XIST/Xist has been induced from the active X by demethylation. Such hybrids had previously been demonstrated to disconnect XIST/Xist expression from gene silencing and we confirm maintenance of X-linked gene expression, even close to the Xist locus, despite the localized expression of mouse Xist.Loss of the active chromatin marks H3 acetylation and H3 lysine 4 methylation was not observed upon XIST/Xist expression, nor was there a gain of DNA methylation; thus these marks of facultative heterochromatin are not solely dependent upon Xist expression. Cot-1 holes, regions of depleted RNA hybridization with a Cot-1 probe, were observed upon Xist expression; however, these were at reduced frequency and intensity in these somatic cells. Domains of human Cot-1 transcription were observed corresponding to the human chromosomes in the somatic cell hybrids. The Cot-1 domain of the X was not reduced with the expression of XIST, which fails to localize to the human X chromosome in a mouse somatic cell background. The human inactive X in a mouse/human hybrid cell also shows delocalized XIST expression and an ongoing Cot-1 domain, despite X-linked gene silencing. These results are consistent with recent reports separating Cot-1 silencing from genic silencing, but also demonstrate repetitive element expression from an otherwise silent X chromosome in these hybrid cells

Regional variation in hospitalization for stroke among Asians/Pacific Islanders in the United States: a nationwide retrospective cohort study

BACKGROUND: In Asia, stroke incidence varies dramatically from country to country. Little is known about stroke incidence in Asians/Pacific Islanders in the US, where regional heterogeneity in Asian/Pacific Islander sub-populations is great. We sought to characterize both the national and regional incidences of first and recurrent hospitalized acute ischemic stroke, subarachnoid hemorrhage, and intracerebral hemorrhage in Asians/Pacific Islanders compared to non-Hispanic whites. METHODS: We used the National Inpatient Sample of the 1997 Healthcare Cost and Utilization Project. It is a 20% stratified sample of hospitalizations to nonfederal hospitals in the US. National and regional projections were made using sampling weights specific for patients and hospitals. We identified stroke subtypes using previously validated ICD-9 codes. Age-adjusted incidence rates were calculated using the direct method with the US population in 2000 as the standard. RESULTS: There were 169,386 stroke hospitalizations in the database. Nationally, compared to whites, Asians/Pacific Islanders were more likely to have subarachnoid hemorrhage (incidence rate ratio {RR} female: 1.53, 95% CI 1.41–1.65; male RR: 1.13, 95% CI 1.00–1.27) and intracerebral hemorrhage (female RR 1.29, 95% CI 1.22–1.36; male RR: 1.58, 95% CI 1.50–1.67). However, when examined by geographic regions, Asians/Pacific Islanders had higher incidence rates of subarachnoid hemorrhage and intracerebral hemorrhage predominantly in the West, and lower rates of stroke elsewhere. CONCLUSION: Stroke incidence varies 3-fold among Asians/Pacific Islanders residing in different US regions. Geographic variation is less dramatic in whites. Whether genetic or cultural differences are responsible for dramatic heterogeneity among Asian/Pacific Islander populations is unclear and deserves further study

Dynasore, a Dynamin Inhibitor, Inhibits Trypanosoma cruzi Entry into Peritoneal Macrophages

BACKGROUND: Trypanosoma cruzi is an intracellular parasite that, like some other intracellular pathogens, targets specific proteins of the host cell vesicular transport machinery, leading to a modulation of host cell processes that results in the generation of unique phagosomes. In mammalian cells, several molecules have been identified that selectively regulate the formation of endocytic transport vesicles and the fusion of such vesicles with appropriate acceptor membranes. Among these, the GTPase dynamin plays an important role in clathrin-mediated endocytosis, and it was recently found that dynamin can participate in a phagocytic process. METHODOLOGY/PRINCIPAL FINDINGS: We used a compound called dynasore that has the ability to block the GTPase activity of dynamin. Dynasore acts as a potent inhibitor of endocytic pathways by blocking coated vesicle formation within seconds of its addition. Here, we investigated whether dynamin is involved in the entry process of T. cruzi in phagocytic and non-phagocytic cells by using dynasore. In this aim, peritoneal macrophages and LLC-MK2 cells were treated with increasing concentrations of dynasore before interaction with trypomastigotes, amastigotes or epimastigotes. We observed that, in both cell lines, the parasite internalization was drastically diminished (by greater than 90% in LLC-MK2 cells and 70% in peritoneal macrophages) when we used 100 microM dynasore. The T. cruzi adhesion index, however, was unaffected in either cell line. Analyzing these interactions by scanning electron microscopy and comparing peritoneal macrophages to LLC-MK2 cells revealed differences in the stage at which cell entry was blocked. In LLC-MK2 cells, this blockade is observed earlier than it is in peritoneal macrophages. In LLC-MK2 cells, the parasites were only associated with cellular microvilli, whereas in peritoneal macrophages, trypomastigotes were not completely engulfed by a host cell plasma membrane. CONCLUSIONS/SIGNIFICANCE: Taken together our results demonstrate that dynamin is an essential molecule necessary for cell invasion and specifically parasitophorous vacuole formation by host cells during interaction with Trypanosoma cruzi

The Status of Dosage Compensation in the Multiple X Chromosomes of the Platypus

Dosage compensation has been thought to be a ubiquitous property of sex chromosomes that are represented differently in males and females. The expression of most X-borne genes is equalized between XX females and XY males in therian mammals (marsupials and “placentals”) by inactivating one X chromosome in female somatic cells. However, compensation seems not to be strictly required to equalize the expression of most Z-borne genes between ZZ male and ZW female birds. Whether dosage compensation operates in the third mammal lineage, the egg-laying monotremes, is of considerable interest, since the platypus has a complex sex chromosome system in which five X and five Y chromosomes share considerable genetic homology with the chicken ZW sex chromosome pair, but not with therian XY chromosomes. The assignment of genes to four platypus X chromosomes allowed us to examine X dosage compensation in this unique species. Quantitative PCR showed a range of compensation, but SNP analysis of several X-borne genes showed that both alleles are transcribed in a heterozygous female. Transcription of 14 BACs representing 19 X-borne genes was examined by RNA-FISH in female and male fibroblasts. An autosomal control gene was expressed from both alleles in nearly all nuclei, and four pseudoautosomal BACs were usually expressed from both alleles in male as well as female nuclei, showing that their Y loci are active. However, nine X-specific BACs were usually transcribed from only one allele. This suggests that while some genes on the platypus X are not dosage compensated, other genes do show some form of compensation via stochastic transcriptional inhibition, perhaps representing an ancestral system that evolved to be more tightly controlled in placental mammals such as human and mouse

Discovery of nucleotide polymorphisms in the Musa gene pool by Ecotilling

Musa (banana and plantain) is an important genus for the global export market and in local markets where it provides staple food for approximately 400 million people. Hybridization and polyploidization of several (sub)species, combined with vegetative propagation and human selection have produced a complex genetic history. We describe the application of the Ecotilling method for the discovery and characterization of nucleotide polymorphisms in diploid and polyploid accessions of Musa. We discovered over 800 novel alleles in 80 accessions. Sequencing and band evaluation shows Ecotilling to be a robust and accurate platform for the discovery of polymorphisms in homologous and homeologous gene targets. In the process of validating the method, we identified two single nucleotide polymorphisms that may be deleterious for the function of a gene putatively important for phototropism. Evaluation of heterozygous polymorphism and haplotype blocks revealed a high level of nucleotide diversity in Musa accessions. We further applied a strategy for the simultaneous discovery of heterozygous and homozygous polymorphisms in diploid accessions to rapidly evaluate nucleotide diversity in accessions of the same genome type. This strategy can be used to develop hypotheses for inheritance patterns of nucleotide polymorphisms within and between genome types. We conclude that Ecotilling is suitable for diversity studies in Musa, that it can be considered for functional genomics studies and as tool in selecting germplasm for traditional and mutation breeding approaches