Whole-body imaging of sequestration of Plasmodium falciparum in the rat

The occlusion of vessels by packed Plasmodium falciparum-infected (iRBC) and uninfected erythrocytes is a characteristic postmortem finding in the microvasculature of patients with severe malaria. Here we have employed immunocompetent Sprague-Dawley rats to establish sequestration in vivo. Human iRBC cultivated in vitro and purified in a single step over a magnet were labeled with 99mtechnetium, injected into the tail vein of the rat, and monitored dynamically for adhesion in the microvasculature using whole-body imaging or imaging of the lungs subsequent to surgical removal. iRBC of different lines and clones sequester avidly in vivo while uninfected erythrocytes did not. Histological examination revealed that a multiadhesive parasite adhered in the larger microvasculature, inducing extensive intravascular changes while CD36- and chondroitin sulfate A-specific parasites predominantly sequester in capillaries, inducing no or minor pathology. Removal of the adhesive ligand Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), preincubation of the iRBC with sera to PfEMP1 or preincubation with soluble PfEMP1-receptors prior to injection significantly reduced the sequestration. The specificity of iRBC binding to the heterologous murine receptors was confirmed in vitro, using primary rat lung endothelial cells and rat lung cryosections. In offering flow dynamics, nonmanipulated endothelial cells, and an intact immune system, we believe this syngeneic animal model to be an important complement to existing in vitro systems for the screening of vaccines and adjunct therapies aiming at the prevention and treatment of severe malaria.     

Immune responses of two Mastomys sibling species to Yersinia pestis.

This study assessed the in vitro cell-mediated immune responses of Mastomys natalensis, with a diploid chromosome number of 2n = 32, and Mastomys coucha, with a diploid chromosome number of 2n = 36, to Yersinia pestis. Splenic mononuclear (MN) cells of uninfected M. natalensis proliferated in response to crude fraction 1 of Y. pestis and two subfractions derived from fraction 1 in vitro. Proliferation was dose dependent and followed the time kinetics of other well-known mitogens. Further characterization of the two fractions revealed similar protein profiles in sodium dodecyl sulfide-polyacrylamide gel electrophoresis and indicated a heat-stable protein of 25 kDa responsible for the mitogenic activity. No such response was observed with MN cells from M. coucha. The unresponsiveness of M. coucha-derived MN cells appears to be related to an inability to respond to Y. pestis organisms. The results may help explain the relative resistance and susceptibility of M. natalensis and M. coucha to Y. pestis infection.     

Mosaicism of the CAG repeat sequence in the Huntington disease gene in a pair of monozygotic twins

We report on a pair of monozygotic twins belonging to a family segregating Huntington disease (HD). In routine DNA analysis of blood cells, they displayed three alleles of the CAG repeat sequence in the HD gene. Two different cell lines, carrying the normal allele together with either an expanded allele with 47 CAGs or an intermediate allele with 37 CAGs, were detected in blood and buccal epithelium from both twins. To our knowledge, this is the first case described of HD gene CAG repeat length mosaicism in blood cells. Haplotype analysis established that the 37 CAG allele most likely arose by contraction of the maternal 47 CAG allele. The contraction must have taken place postzygotically, possibly at a very early stage of development, and probably before separation of the twins. One of the twins has presented symptoms of HD for 4 years; his skin fibroblasts and hair roots carried only the cell line with the 47 CAG repeat allele. The other twin, who is without symptoms at present, displayed mosaicism in skin fibroblasts and hair roots. If the proportion of the two cell lines in the brain of each twin resembles that of their hair roots (another tissue originating from the ectoderm), the mosaicism in the unaffected twin would mean that only a part of his brain cells carried the expanded allele, which could explain why he, in contrast to his brother, has no symptoms at this time.     

High-throughput single strand conformation polymorphism mutation detection by automated capillary array electrophoresis: validation of the method

Capillary array electrophoresis (CAE) is a novel technique, which allows for high throughput analysis of DNA fragments. When screening for mutations in whole populations or large patient groups it is necessary to have robust and well-characterized setups for high throughput analysis. For large-scale mutation screening, we have developed procedures for single strand conformation polymorphism (SSCP) assays using CAE (CAE-SSCP) whereby we may increase both the sensitivity and the throughput compared to conventional SSCP analysis. In this study we have validated CAE-SSCP by 1) comparing detection by slab-gel based SSCP with CAE-SSCP of mutations in the MYH7, MYL2, and MYL3 genes encoding sarcomere proteins from patients suffering from hypertrophic cardiomyopathy; and 2) by constructing a series of 185 mutants having substitution mutations, as well as insertion/deletion mutations, or some combinations of these, in different sequence contexts in four exons and different positions relative to the end of the amplicon (three from the KCNQ1 gene, encoding a cardiac potassium channel, and one from the TNNI3 gene encoding cardiac troponin I). The method identified 181 out of 185 mutations (98%), and the data suggest that the position of mutation in the fragment had no effect on the sensitivity. Analysis of the specificity of the method showed that only very few mutants could not be distinguished from each other and there were no false positives.     

Progenitor cells in liver regeneration: molecular responses controlling their activation and expansion

Although normally quiescent, the adult mammalian liver possesses a great capacity to regenerate after different types of injuries in order to restore the lost liver mass and ensure maintenance of the multiple liver functions. Major players in the regeneration process are mature residual cells, including hepatocytes, cholangiocytes and stromal cells. However, if the regenerative capacity of mature cells is impaired by liver-damaging agents, hepatic progenitor cells are activated and expand into the liver parenchyma. Upon transit amplification, the progenitor cells may generate new hepatocytes and biliary cells to restore liver homeostasis. In recent years, hepatic progenitor cells have been the subject of increasing interest due to their therapeutic potential in numerous liver diseases as alternative or supportive/complementary tools to liver transplantation. While the first investigations on hepatic progenitor cells have focused on their origin and phenotypic characterization, recent attention has focused on the influence of the hepatic microenvironment on their activation and proliferation. This microenvironment comprises the extracellular matrix, epithelial and non-epithelial resident liver cells, and recruited inflammatory cells as well as the variety of growth-modulating molecules produced and/or harboured by these elements. The cellular and molecular responses to different regenerative stimuli seem to depend on the injury inflicted and consequently on the molecular microenvironment created in the liver by a certain insult. This review will focus on molecular responses controlling activation and expansion of the hepatic progenitor cell niche, emphasizing similarities and differences in the microenvironments orchestrating regeneration by recruitment of progenitor cell populations or by replication of mature cells.     

Expression of vascular endothelial growth factor (VEGF)-D and its receptor, VEGF receptor 3, as a prognostic factor in endometrial carcinoma.

PURPOSE: To evaluate the prognostic value of vascular endothelial growth factor (VEGF)-D and VEGF receptor (VEGFR)-3 in endometrial carcinoma. EXPERIMENTAL DESIGN: We assessed the levels of immunoreactivity for VEGF-D and VEGFR-3 in 71 endometrial carcinomas, 14 complex atypical endometrial hyperplasias, and 16 normal endometria by immunohistochemistry. RESULTS: VEGF-D was stained in both tumor cells and adjacent stromal cells. VEGFR-3 was stained in both tumor cells and adjacent endothelial cells. Immunoreactivity for VEGF-D in tumor cells and adjacent stromal cells became significantly stronger as lesions progressed from normal endometrium to advanced carcinoma. Similarly, immunoreactivity for VEGFR-3 in tumor cells and adjacent endothelial cells was significantly greater as lesions progressed from normal endometrium to advanced carcinoma. A strong correlation was found between high levels of VEGF-D immunoreactivity in carcinoma cells and VEGFR-3 in both carcinoma cells and adjacent endothelial cells. Similarly, high levels of VEGF-D immunoreactivity in stromal cells were significantly correlated with those of VEGFR-3 in both carcinoma cells and endothelial cells. High levels of VEGF-D in carcinoma cells and stromal cells, as well as those of VEGFR-3 in carcinoma cells and endothelial cells, were significantly related to myometrial invasion and lymph node metastasis. A strong correlation was found between poor survival and high levels of VEGF-D in both carcinoma cells and stromal cells and between poor survival and high levels of VEGFR-3 in carcinoma cells. Moreover, the high levels of VEGF-D in stromal cells and VEGFR-3 in carcinoma cells were independent prognostic factors in endometrial carcinoma. CONCLUSIONS: The presence of VEGF-D and VEGFR-3 in endometrial carcinoma may predict myometrial invasion and lymph node metastasis and may prospectively identify patients who are at increased risk for poor outcome. In addition, VEGF-D and VEGFR-3 may be promising targets for new therapeutic strategies in endometrial carcinoma.     

Early prenatal vitamin D concentrations and social-emotional development in infants

Background: Many pregnant women in the United States have suboptimal vitamin D, but the impact on infant development is unclear. Moreover, no pregnancy-specific vitamin D recommendations have been widely accepted.

Aims: Given the ubiquitous expression of vitamin D receptors in the brain, we investigated the association between early prenatal plasma 25-hydroxyvitamin D (25(OH)D) concentrations and children’s social and emotional development in the Newborn Epigenetic Study, a prospective study of pregnancies from 2009 to 2011 in Durham, North Carolina.

Methods: We measured 25(OH)D concentrations in first or second trimester plasma samples and categorized 25(OH)D concentrations into quartiles. Covariates were derived from maternal questionnaires. Mothers completed the Infant Toddler Social-Emotional Development Assessment when children were 12–24 months of age. We used multivariable linear regression to evaluate associations between 25(OH)D and specific behavior scores, adjusted for season of blood draw, maternal age, education, parity, smoking, marital status, prepregnancy BMI, and infant gender. We investigated effect-measure modification by race/ethnicity.

Results: Of the 218 mother–infant pairs with complete data, Black mothers had much lower 25(OH)D concentrations as compared to White and Hispanic mothers. After adjustment, lower prenatal 25(OH)D was associated with slightly higher (less favorable) Internalizing scores among White children, but lower (more favorable) Internalizing scores among Black and Hispanic children. Lower prenatal 25(OH)D also appears to be associated with higher (less favorable) dysregulation scores, though only among White and Hispanic children.

Conclusions: Though imprecise, preliminary results warrant further investigation regarding a role for prenatal vitamin D on children’s early social and emotional development.