Moving actuator type total artificial heart with reverse position of the aortic and pulmonary conduits

Adequate intrathoracic anatomical compatibility is one of the most important considerations in designing a fully implantable total artificial heart (TAH). We have recently developed an innovative concept of reverse positioning of the aortic and pulmonary conduits to facilitate anatomical compatibility of the moving actuator type TAH. The pulmonary conduit of this TAH is designed to be located posterior to the aortic conduit, which results in a substantial reduction in the anteroposterior diameter of this heart, as well as the virtual elimination of the compression of the low pressure pulmonary conduit. In ovine orthotopic implantation experiments with this model of the TAH, we consecutively achieved 3 day survival in 1 sheep and 2 day survival in another. To the best of our knowledge, these were the first significant short-term survival cases in the orthotopic implantation of electric TAHs in sheep.     

Exposure of primary rat hepatocytes in long-term DMSO culture to selected transition metals induces hepatocyte proliferation and formation of duct-like structures

We previously showed that primary rat hepatocytes plated on a rat-tail collagen coated dish and fed a chemically-defined medium supplemented with 2% dimethylsulfoxide (DMSO) can be maintained in a well-differentiated, non-replicating state for periods of several months. In this study, we show that the addition of copper, iron, and zinc to the DMSO-containing chemically defined medium induced DNA synthesis and cell replication during the first two months in culture without loss of hepatic differentiation. DNA synthesis occurred throughout the hepatocyte population without regard to cellular size. No changes were observed in properties indicative of well-differentiated hepatocytes, including cellular morphology, ultrastructure, albumin, or cytokeratin-8 expression. During the third month in culture, after the hepatocytes had become confluent, pseudoduct structures became apparent. Examination of cells lining the ducts by immunohistochemistry showed that these cells lost the ability to express albumin and stained more intensely for cytokeratin 19 and laminin. The ultrastructure of the cells lining the ducts was altered and became more characteristic of bile duct cells. Immunoelectron microscopy revealed that connexin 43, a marker of bile-duct proliferation, was expressed in the duct-like cells. We conclude that under these specific nutritive conditions, primary rat hepatocytes proliferate and, with time, begin to form duct-like structures with altered gene expression and ultrastructural properties.     

The nonrandom binding distribution of Streptococcus pneumoniae to type II pneumocytes in culture is dependent on the relative distribution of cells among the phases of the cell cycle

The adherence of Streptococcus pneumoniae to epithelial (A549) lung cells was studied and the bacterial binding distribution was found to be nonrandom (non-Gaussian). Analysis of the dependency of bacterial binding on the cell cycle of A549 cells revealed that approximately 1.8 times more bacteria bind to G2 cells than to G0-G1 phase cells. Furthermore, bacterial binding curves exhibited a plateau of binding to G2 cells at a normalized bacteria to cell ratio approximately 1.8 times larger than that at which the plateau of binding to G0-G1 cell was observed. Since G2 cells are on average 1.4-1.8 times larger than G0-G1 cells, the results indicate that bacterial binding is proportional to cell size and not to the preferential binding (higher affinity) of bacteria to A549 cells in the G2 phase. Finally, the non-Gaussian distribution of bacterial binding could be mathematically modeled by a linear combination of three Gaussian distributions each representing bacterial binding to cells in a particular phase of the cell cycle (G0-G1, S, and G2-M). Because the Gaussian function contains a term that takes into account the relative number of cells in each of the phases, this last result implies that the overall (non-Gaussian) binding distribution (and hence the median of bacterial binding) can be highly sensitive to the relative proportion of cells in the various phases of the cell cycle.     

Regression of vessels in the tunica vasculosa lentis is initiated by coordinated endothelial apoptosis: a role for vascular endothelial growth factor as a survival factor for endothelium

This review is concerned with the application of the method of differential scanning calorimetry (DSC) to structural and functional studies of myosin and actin--the main two proteins of muscles and many other systems of biological motility. The domain organization of these proteins as revealed by DSC is considered. Data are presented on the conformational changes which occur in the myosin head and in F-actin due to the formation of the ternary complexes with ADP and Pi analogs (such as orthovanadate, beryllium fluoride, or aluminum fluoride). Recent data on the application of DSC to studies on the interaction of F-actin with myosin heads and with tropomyosin are also considered. It is concluded that DSC offers a new and promising approach to probe the structural changes which occur in the myosin head and in F-actin during ATP hydrolysis and due to interaction of these proteins with each other.     

Linking self-reported childhood behavioral inhibition to adolescent social phobia

OBJECTIVE: Behavioral inhibition in children has been hypothesized to be a risk factor for the later development of social phobia. However, this hypothesis has yet to be demonstrated in a prospective study. The purpose of the study presented here is to test whether behavioral inhibition in childhood constitutes a risk factor for social phobia during adolescence. METHOD: The sample consisted of 2,242 high school students assessed over a 4-year period. Assessments included self-report questionnaires, structured clinical interviews, and measurements of heart rate. Cox proportional hazards models were used to evaluate risk. RESULTS: Social avoidance, a component of behavioral inhibition, predicted onset of social phobia during high school. However, social avoidance was not related to depression in adolescence. Another component of behavioral inhibition, fearfulness, increased the risk for both social phobia and depression. Among subjects who were both socially avoidant and fearful, 22.3% developed social phobia--a risk more than four times greater than that for subjects with neither feature of behavioral inhibition. CONCLUSION: This prospective study demonstrates that behavioral inhibition in childhood increases the risk of social phobia in adolescence.