Microengineered systems with iPSC-derived cardiac and hepatic cells to evaluate drug adverse effects

Hepatic and cardiac drug adverse effects are among the leading causes of attrition in drug development programs, in part due to predictive failures of current animal or in vitro models. Hepatocytes and cardiomyocytes differentiated from human induced pluripotent stem cells (iPSCs) hold promise for predicting clinical drug effects, given their human-specific properties and their ability to harbor genetically determined characteristics that underlie inter-individual variations in drug response. Currently, the fetal-like properties and heterogeneity of hepatocytes and cardiomyocytes differentiated from iPSCs make them physiologically different from their counterparts isolated from primary tissues and limit their use for predicting clinical drug effects. To address this hurdle, there have been ongoing advances in differentiation and maturation protocols to improve the quality and use of iPSC-differentiated lineages. Among these are in vitro hepatic and cardiac cellular microsystems that can further enhance the physiology of cultured cells, can be used to better predict drug adverse effects, and investigate drug metabolism, pharmacokinetics, and pharmacodynamics to facilitate successful drug development. In this article, we discuss how cellular microsystems can establish microenvironments for these applications and propose how they could be used for potentially controlling the differentiation of hepatocytes or cardiomyocytes. The physiological relevance of cells is enhanced in cellular microsystems by simulating properties of tissue microenvironments, such as structural dimensionality, media flow, microfluidic control of media composition, and co-cultures with interacting cell types. Recent studies demonstrated that these properties also affect iPSC differentiations and we further elaborate on how they could control differentiation efficiency in microengineered devices. In summary, we describe recent advances in the field of cellular microsystems that can control the differentiation and maturation of hepatocytes and cardiomyocytes for drug evaluation. We also propose how future research with iPSCs within engineered microenvironments could enable their differentiation for scalable evaluations of drug effects.     

Aberrant epigenetic and genetic marks are seen in myelodysplastic leukocytes and reveal Dock4 as a candidate pathogenic gene on chromosome 7q

Myelodysplastic syndromes (MDS) are characterized by abnormal and dysplastic maturation of all blood lineages. Even though epigenetic alterations have been seen in MDS marrow progenitors, very little is known about the molecular alterations in dysplastic peripheral blood cells. We analyzed the methylome of MDS leukocytes by the HELP assay and determined that it was globally distinct from age-matched controls and was characterized by numerous novel, aberrant hypermethylated marks that were located mainly outside of CpG islands and preferentially affected GTPase regulators and other cancer-related pathways. Additionally, array comparative genomic hybridization revealed that novel as well as previously characterized deletions and amplifications could also be visualized in peripheral blood leukocytes, thus potentially reducing the need for bone marrow samples for future studies. Using integrative analysis, potentially pathogenic genes silenced by genetic deletions and aberrant hypermethylation in different patients were identified. DOCK4, a GTPase regulator located in the commonly deleted 7q31 region, was identified by this unbiased approach. Significant hypermethylation and reduced expression of DOCK4 in MDS bone marrow stem cells was observed in two large independent datasets, providing further validation of our findings. Finally, DOCK4 knockdown in primary marrow CD34(+) stem cells led to decreased erythroid colony formation and increased apoptosis, thus recapitulating the bone marrow failure seen in MDS. These findings reveal widespread novel epigenetic alterations in myelodysplastic leukocytes and implicate DOCK4 as a pathogenic gene located on the 7q chromosomal region.     

A polyclonal antiserum to the noncatalytic part of cellobiohydrolase I fromTrichoderma reesei

A specific antiserum to the noncatalytic part of cellobiohydrolase I fromTrichoderma reesei was obtained by exhaustion of rabbit antiserum to the native enzyme with its catalytic domain prepared by papain treatment of cellobiohydrolase I tightly adsorbed onto microcrystalline cellulose.     

Synthesis and structure-activity studies of novel benzocycloheptanone oxazolidinone antibacterial agents

We describe a novel class of benzocycloheptanone derived oxazolidinone antibacterial agents. The synthesis and antibacterial activities with structure variation is discussed.     

The Effects of Social Structure, Geographical Structure, and Population Size on the Evolution of Mitochondrial DNA: II. Molecular Clocks and the Lineage Sorting Period

Evolutionary geneticists have increasingly used sequence variation in mitochondrial DNA (mtDNA) as a source of historical information. However, conclusions based on these data remain tentative because a sufficiently clear understanding of the evolutionary dynamics of mtDNA has yet to be developed. In this paper we present the results of computer simulations designed to illustrate the effects of social structure, geographical structure, and population size on the rate of nucleotide substitution and lineage sorting of mtDNA. The model is based in part on the social structure of macaque monkeys. Simulated populations of females were divided into 25 social groups; the animals in each were distributed in a hierarchy of four dominance rank categories. The probabilities for offspring survivorship were varied among dominance ranks to reflect the fitness consequences of social structure. Population size was varied across runs from 100 to 300 females. The pattern of female migration was also varied to mimic either the island model or the stepping-stone model. All these variables are shown to affect the lineage sorting period (LSP), and certain combinations of parameter values can cause the retention of mtDNA polymorphisms for a very long time. In addition, the simulations exhibited a negative relationship between the LSP and substitution rate over a modest and realistic range of LSP values. An important implication of these results is that estimates of time since isolation based on the assumption of a constant molecular clock may be biased and unreliable.     

An analysis of cercopithecoid odontometrics. II. Relations between dental dimorphism, body size dimorphism and diet.

Odontometric, dietary, and body weight data were collected for a sample of 29 cercopithecoid species. Each species was assigned to one of three diet classes (frugivore, folivore, and omnivore) , and indices were constructed to estimate the extent of sexual dimorphism in body weight, postcanine area and incisor width in each of the species. Analysis proceeded by means of the analysis of covariance with the dental dimorphism indices as the dependent variables. Body weight dimorphism was not significantly related to either measure of dental dimorphism across the sample, and an analysis by diet alone revealed that omnivores show significantly higher dental dimorphism than do either of the other two diet classes. The relationship between this result and theories of sexual subniche differentiation is discussed.