Effect of Echis coloratus venom on brain vessels

The effect of Echis coloratus venom on the brain capillaries of the mouse was studied electron-microscopically using horseradish peroxidase as a tracer. The envenomation resulted in breakdown of the blood-brain barrier manifested by leakage of the peroxidase through the capillary wall. The peroxidase penetrated both by endothelial pinocytosis and through opened tight junctions between the endothelial cells. The envenomated mice showed hemorrhages and intravascular fibrin clots in the lungs and kidneys but not in the brain.     

ISOLATION AND CHARACTERIZATION OF A NEW TRYPSIN-LIKE ENZYME FROM: Tenebrio molitor L. LARVAE

A trypsin-like enzyme (TLE) was separated and purified from Tenebrio molitor larval midgut enzyme solution by ion-exchange chromatography on a DEAE-cellulose column. The purified enzyme was found to be a homogeneous protein by electrophoresis in polyacrylamide gels and on cellulose acetate strips, by electrofocusing in polyacrylamide gels and by SDS-polyacrylamide gel electrophoresis. Its molecular weight was estimated to be 18300 by ultracentrifugal analysis and 24300 on SDS-polyacrylamide gel electrophoresis. It has an isoelectric point 8.0, it contains only four half-cystine residues per molecule and the NH₂-terminal amino acid is isoleucine. TLE possesses a high degree of specificity towards trypsin synthetic substrates such as N-α-benzoyl-DL-arginine p-nitroanilide (BAPNA), p-tosyl-L-arginine methyl ester (TAME) and poly-L-lysine hydrobromide. The optimal pH for TLE activity was found to be 8.0 and the optimal temperature 50° C. Its Km value when assayed on BAPNA was 0.93mM and on TAME 0.08mM. TLE is stable at neutral pHs and its activity is not affected by Ca²⁺ and by 0.01 M 1, 4-dithiothreitol (DTT). It is inactivated by DFP and tosyl-L-lysine chloromethylketone (TLCK) and is fully inhibited by the naturally occurring trypsin inhibitors such as trypsin-and α-chymotrypsin inhibitor (AA) from soybeans, basic pancreatic trypsin inhibitor (BPTI), chick peas trypsin and chymotrypsin inhibitor (CI) and crystalline soybean trypsin inhibitor (CSBTI), forming with them complexes in a molar ratio of 1:1. The Ki value for AA with BAPNA as substrate is 5.87 10^-7 M and for BPTI 7.92 10^-7M. No common antigenic determinants were noted between TLE and bovine trypsin. This finding together with the relatively low number of -S-S- bonds in the TLE molecule indicate that TLE differs in conformation from bovine trypsin.     

The effect of chilling on membrane lipid phase transition in human oocytes and zygotes

BACKGROUND: Chilling injury occurs when the cell membrane undergoes a transition from the liquid state to the gel state. Human oocytes and single-cell zygotes are of similar shape and size but the post-thawing survival rate of oocytes is poorer. We set out to investigate the possible difference in membrane lipid phase transition (LPT) temperature between the two cell types. METHODS: The LPT temperature was measured with a Fourier Transform Infrared analyser, which detects the change in the vibration frequency of the CH2 bond stretches of the membrane lipid molecules during temperature change. The LPT temperatures of unfertilized human oocytes, in vitro-matured oocytes, and immature germinal vesicle (GV) stage oocytes were compared with that of abnormally fertilized human zygotes. RESULTS: The LPT temperatures of zygotes and of mature and immature GV oocytes differ significantly from each other (10.0 +/- 1.2, 16.9 +/- 0.9 and 24.4 +/- 1.6 degrees C respectively; P < 0.05). CONCLUSIONS: Zygotes show a higher resistance to chilling injury compared to oocytes at different developmental stages; this might explain the relatively poor survival rates of cryopreserved human oocytes and indicates the necessity to adjust the cryopreservation protocols in order to minimize cryoinjury.     

Axiomatic scalable neurocontroller analysis via the Shapley value

One of the major challenges in the field of neurally driven evolved autonomous agents is deciphering the neural mechanisms underlying their behavior. Aiming at this goal, we have developed the multi-perturbation Shapley value analysis (MSA)--the first axiomatic and rigorous method for deducing causal function localization from multiple-perturbation data, substantially improving on earlier approaches. Based on fundamental concepts from game theory, the MSA provides a formal way of defining and quantifying the contributions of network elements, as well as the functional interactions between them. The previously presented versions of the MSA require full knowledge (or at least an approximation) of the network's performance under all possible multiple perturbations, limiting their applicability to systems with a small number of elements. This article focuses on presenting new scalable MSA variants, allowing for the analysis of large complex networks in an efficient manner, including large-scale neurocontrollers. The successful operation of the MSA along with the new variants is demonstrated in the analysis of several neurocontrollers solving a food foraging task, consisting of up to 100 neural elements.     

Improved immune function with donor B-cell infusion after semi-allogeneic bone marrow transplantation in mice

BACKGROUND: Regeneration of the immune system after bone marrow transplantation (BMT) is a slow process, often prolonged by the development and treatment of graft vs. host disease (GVHD). Donor lymphocyte infusion using allogeneic T-cells is widely applied for the induction of GVHD, which is associated with the desired graft vs. leukemia effect. Due to the slow immune recovery, our objective was to accelerate the immune recovery post-BMT by B-cell injections. METHODS: T-cell-depleted stem cells obtained from female C57BL/6 (B6) mice were transplanted into lethally irradiated (Balb/c x C57BL/6) F-1 female mice. Seven days post-transplantation, murine B-cells of male C57BL/6 origin were infused into the T-cell-depleted chimeras. Thirty and 60 days post-transplantation, PCR analysis of the Y-chromosome was carried out to detect male B-cells in the transplant recipients. In order to evaluate the specific antibody response, the donors were immunized by specific T-cell-dependent and -independent antigens. RESULTS: None of the T-cell-depleted transplanted mice developed GVHD during a follow-up period of 650 days, whereas all non-T-cell-depleted recipients died. At 60 days post-transplantation, significantly higher levels of immunoglobulins (IgA, IgG1, IgG3 isotypes) were seen in chimeras supplemented with male B-cells than in chimeras reconstituted with T-cell-depleted stem cells alone. CONCLUSIONS: Our data document the feasibility of administering B-cell therapy post-allogeneic BMT to improve recovery of the humeral arm of the immune system while avoiding GVHD. Furthermore, post-transplant B-cell administration may have an important impact as an alternative to IV immunoglobulin infusions.     

The chemokine SDF-1 stimulates integrin-mediated arrest of CD34+ cells on vascular endothelium under shear flow

The chemokine SDF-1 plays a central role in the repopulation of the bone marrow (BM) by circulating CD34(+) progenitors, but the mechanisms of its action remain obscure. To extravasate to target tissue, a blood-borne cell must arrest firmly on vascular endothelium. Murine hematopoietic progenitors were recently shown in vivo to roll along BM microvessels that display selectins and integrins. We now show that SDF-1 is constitutively expressed by human BM endothelium. In vitro, human CD34(+) cells establish efficient rolling on P-selectin, E-selectin, and the CD44 ligand hyaluronic acid under physiological shear flow. ICAM-1 alone did not tether CD34(+) cells under flow, but, in the presence of surface-bound SDF-1, CD34(+) progenitors rolling on endothelial selectin rapidly developed firm adhesion to the endothelial surface, mediated by an interaction between ICAM-1 and its integrin ligand, which coimmobilized with SDF-1. Human CD34(+) cells accumulated efficiently on TNF-activated human umbilical cord endothelial cells in the absence of SDF-1, but they required immobilized SDF-1 to develop firm integrin-mediated adhesion and spreading. In the absence of selectins, SDF-1 also promoted VLA-4-mediated, Gi protein-dependent tethering and firm adhesion to VCAM-1 under shear flow. To our knowledge, this is the first demonstration that SDF-1 expressed on vascular endothelium is crucial for translating rolling adhesion of CD34(+) progenitors into firm adhesion by increasing the adhesiveness of the integrins VLA-4 and LFA-1 to their respective endothelial ligands, VCAM-1 and ICAM-1.     

The estrogen receptors in the papillary carcinoma of the thyroid gland

In this study, the objective was to evaluate the presence of estrogen receptors alpha and beta (ERalpha and ERbeta) in cases of papillary carcinoma of the thyroid gland and to assess the practicality of this test. Immunohistochemical stains were performed for both ERalpha and ERbeta, for evaluation of immunoreactivity in 90 papillary carcinomas. Three variables were evaluated in each sample: the intensity of the staining both nuclear and cytoplasmatic, and the spread of the stain over the sample. None of the histological samples showed immunoreactivity for ERalpha. Positive immunoreactivity results for ERbeta were found in tissue samples in 66.6% (60 cases). The study shows that ERbeta has no significant specification for differentiation between papillary carcinoma and other malignant lesions of the thyroid, while ERalpha is undetectable in this lesion. The ER testing in cases of papillary carcinoma of the thyroid gland is nonspecific and might be not necessary.