Spatiotemporal Correlations between Blood-Brain Barrier Permeability and Apparent Diffusion Coefficient in a Rat Model of Ischemic Stroke

Variations in apparent diffusion coefficient of water (ADC) and blood-brain barrier (BBB) permeability after ischemia have been suggested, though the correlation between ADC alterations and BBB opening remains to be studied. We hypothesized that there are correlations between the alteration of ADC and BBB permeability. Rats were subjected to 2 h of transient middle cerebral artery occlusion and studied at 3 and 48 h of reperfusion, which are crucial times of BBB opening. BBB permeability and ADC values were measured by dynamic contrast-enhanced MRI and diffusion-weighted imaging, respectively. Temporal and spatial analyses of the evolution of BBB permeability and ADC alteration in cortical and subcortical regions were conducted along with the correlation between ADC and BBB permeability data. We found significant increases in BBB leakage and reduction in ADC values between 3 and 48 h of reperfusion. We identified three MR tissue signature models: high K_i and low ADC, high K_i and normal ADC, and normal K_i and low ADC. Over time, areas with normal K_i and low ADC transformed into areas with high K_i. We observed a pattern of lesion evolution where the extent of initial ischemic injury reflected by ADC abnormalities determines vascular integrity. Our results suggest that regions with vasogenic edema alone are not likely to develop low ADC by 48 h and may undergo recovery.     

Functional gene groups are concentrated within chromosomes,among chromosomes and in the nuclear space of the human genome

Genomes undergo changes in organization as a result of gene duplications, chromosomal rearrangements and local mutations, among other mechanisms. In contrast to prokaryotes, in which genes of a common function are often organized in operons and reside contiguously along the genome, most eukaryotes show much weaker clustering of genes by function, except for few concrete functional groups. We set out to check systematically if there is a relation between gene function and gene organization in the human genome. We test this question for three types of functional groups: pairs of interacting proteins, complexes and pathways. We find a significant concentration of functional groups both in terms of their distance within the same chromosome and in terms of their dispersal over several chromosomes. Moreover, using Hi-C contact map of the tendency of chromosomal segments to appear close in the 3D space of the nucleus, we show that members of the same functional group that reside on distinct chromosomes tend to co-localize in space. The result holds for all three types of functional groups that we tested. Hence, the human genome shows substantial concentration of functional groups within chromosomes and across chromosomes in space.     

Evaluation and indirect estimation of nitrate losses from the agricultural microbasin Rybárik

The long-term trends of mean monthly nitrate concentrations in stream and drainage runoff were evaluated in the experimental microbasin Rybárik (0.119 km²) at the Institute of Hydrology, Slovak Academy of Sciences, during the period 1987–2005. The results of analyses indicate a decreasing trend of nitrate concentration after the year 1989, but with relatively high losses in some years and relatively low losses in other years. This decreasing trend is mainly caused by a decrease in the use of nitrogen fertilizers. The nitrate concentration in surface runoff strongly correlates with runoff and fertilization. Based on measured data, an empirical relation was found describing the dependence of annual nitrate transport in the stream on annual runoff depth and on the annual amount of applied nitrogen fertilizers. Presented at the International Conference on Bioclimatology and Natural Hazards, Poľana nad Detvou, Slovakia, 17–20 September 2007.     

distruct: a program for the graphical display of population structure

In analysis of multilocus genotypes from structured populations, individual coefficients of membership in subpopulations are often estimated using programs such as structure . distruct provides a general method for visualizing these estimated membership coefficients. Subpopulations are represented as colours, and individuals are depicted as bars partitioned into coloured segments that correspond to membership coefficients in the subgroups. distruct , available at http://www.cmb.usc.edu/~noahr/distruct.html , can also be used to display subpopulation assignment probabilities when individuals are assumed to have ancestry in only one group.     

In vitro growth of murine T cells. II. Growth of in vitro sensitized cells cytotoxic for alloantigens.

Growth factors (GM), produced by murine lymphoid cells incubated with Concanavalin A, have been used to grow cytotoxic lymphoid cells in culture. C57BL/6 and DBA/2 lymphoid cells were sensitized against each other in primary, secondary, and tertiary in vitro cultures. These sensitized cells were grown in vitro in GM and retained their cytotoxic properties. Cells grew in culture about 10-fold every 5 to 7 days for over 2 months. Initial growth of cytotoxic cells in GM resulted in marked enhancement of specific cytotoxicity that returned to original levels after subsequent subcultures. After five 10-fold cell culture generations some nonspecific cytotoxicity directed against the responding target cell strain appeared in continuous cultures. This technique for growing large numbers of cytotoxic cells may be of value in the development of adoptive immunotherapies.     

Chemiluminescence in Dictyostelium discoideum

Abstract Oxygen radicals generated during oxidative metabolism participate in chemical reactions resulting in light emission. Chemiluminescence is used therefore to measure their production. We have shown that starvation and heat shock induce chemiluminescence in Dictyostelium discoideum . The peak light emission was found to occur about 4 h after the onset of starvation. The optimum temperature for chemiluminescence by starving amoebae was about 33°C. The heat shock inducibility of chemiluminescence was maximal at the beginning of development. Our results are consistent with suggestions that the product(s) of perturbed mitochondrial metabolism might be intracellular signal(s) controlling gene expression in stressed cells. They also suggest a role for intracellular stress signal(s) in the initiation of development in Dictyostelium by starvation.     

Inherited deficiencies of human methylmalonyl CaA mutase activity: reduced affinity of mutant apoenzyme for adenosylcobalamin.

We have studied the affinity of methylmalonyl CoA mutase for its required cofactor, adenosylcobalamin, in extracts of control and mutant human cultured fibroblasts. Control enzyme has an apparent K_m for adenosylcobalamin of 6–7 × 10^?8 M. Five mutant cell lines from patients with methylmalonicacidemia due to a mutase apoenzyme defect were studied. Three have undetectable mutase activity (<0.15% of control) at all cofactor concentrations. Two others, however, have markedly altered K_m's for adenosylcobalamin of 2.8 × 10^?4 M and 1.7 × 10^?5 M. These mutant lines synthesize adenosylcobalamin normally and, by complementation analysis, are genetically identical to all other mutase apoenzyme mutants tested. We conclude that the mutase deficiency in these two cell lines results from structurally altered mutase apoenzymes with markedly reduced affinities for adenosylcobalamin.