Investigations of neurotoxicity and neuroprotection within the nucleus basalis of the rat

The present study investigated the specific ways by which cytotoxicity due to glutamate receptor stimulation could be attenuated by the administration of agonists and antagonists of the ionotropic and metabotropic glutamate receptors within the nucleus basalis magnocellularis (NBM) of rats as measured by cortical choline acetyltransferase activity. The results of these studies suggest that (1) the cytotoxicity of ibotenate to NBM cholinergic cells is not dependent upon stimulation of metabotropic glutamate receptors, but results from activation of (NMDA) receptors, (2) the cytotoxicity of quisqualate to cholinergic cells within the NBM is not dependent upon stimulation of NMDA or metabotropic receptors, and (3) the cytotoxicity of NMDA was prevented by administration (i.p.) of the un-competitive NMDA antagonist memantine (30 mg/kg), resulting in plasma levels of 2.5 μg/ml, a concentration known to block efficiently NMDA receptors in vitro. Finally, performance of a food-motivated, delayed-alternation task on a T-maze was impaired by injections of NMDA into the NBM, but was prevented by co-administration of NMDA with memantine.     

Solvent effects on free-radical polymerization, 5. Analysis of homopolymerization rate on the basis of the reactant-solvent complex model

The rate of polymerization was described as a function of the monomer concentration of 36 monomer/solvent systems in terms of the reactant-solvent complex (RSC) model. One-, two-and three-parameter optimization procedures were used to fit the rate function to experimental data. Fitting increments were the complex equilibrium constant K and the relative monomer reactivity parameter r₁₁. Irrespective of the optimization procedure, K and r₁₁, were found to correlate with the monomer exponent n and to be K = 0 and r₁₁, = 1 at n = 1. In these cases the RSC model reduces to the classical rate model. Despite the weak character of the monomer (radical)/solvent complexation, this interaction should not be neglected in rate modelling. The RSC model is a convenient tool to describe the chain propagation separately.     

Changes in intra-abdominal pressure and central venous and brain venous blood pressure in patients during extracorporeal circulation.

BACKGROUND: The aim was to analyze IAP changes and the relationships between IAP, CVP, and brain venous blood pressure, which are still unknown, in patients undergoing coronary artery bypass grafting (CABG) with extracorporeal circulation. MATERIAL/METHODS: Twenty-five male patients (aged 53-67 years) underwent CABG under general anesthesia with normovolemic hemodilution. IAPs were measured in the urinary bladder, CVP by left internal jugular vein cannulation, and brain venous blood pressure by retrograde cannulation of the right jugular vein bulb (JVP, jugular vein pressure) at seven time-points: 1) after induction of anesthesia before the operation, 2) during internal thoracic artery preparation, 3) 10 minutes after heart-lung machine disconnection, 4) after procedure completion, before sending the patient to the intensive postoperative care unit, 5) one hour after the procedure, 6) 6 hours after the procedure, and 7) 18 hours after the procedure. RESULTS: IAP increased from points 3 to 6. CVP increased from points 3, 4, and 5 and decreased at point 7. Similar changes were noted in JVP. There were significant correlations between IAP and CVP at points 1, 2, 3, 4, and 5, IAP and JVP at points 3, 4, and 5, and CVP and JVP at all points. The overall analysis showed correlations between IAP and CVP and JVP and very strong correlation between CVP and JVP. CONCLUSIONS: 1) CABG with extracorporeal circulation resulted in increases in IAP, CVP, and brain venous blood pressure. 2) The changes in CVP and brain venous blood pressure correlated with intra-abdominal pressure.     

Concentration of TBA-reactive substances in type II pneumocytes exposed to oxidative stress

INTRODUCTION: Oxidative lung damage may be associated with the destruction of alveolar cells. Type II alveolar epithelial cells (AECs),as progenitors of type I cells, are indispensable for the renovation of alveolar structure after lung injury. Extensive damage to type II cells could be responsible for unfavorable outcome. However, the susceptibility of type II AECs to oxidative stress is unclear. MATERIAL/METHODS: We investigated the susceptibility of freshly isolated and cultured rat type II AECs to oxidative stress (H2O2 and Fe2+). Thiobarbituric acid reactive substances (TBARS)were measured as indices of lipid peroxidation and cytotoxicity was estimated by the MTT test. Aminotriazol (ATZ), an inhibitor of intracellular catalase, was used to estimate the protective role of catalase. RESULTS: TBARS concentration increased significantly in freshly isolated, oxidant-exposed cells (4.0 +/-1.3 vs.8.3 +/-2.2 nmol/g protein, p=0.0313)and insignificantly in cultured cells (1.7 +/-0.4 vs.4.4 +/-1.7 nmol/g protein).ATZ was toxic even to cells not exposed to oxidants. Inhibition of catalase in cells exposed to oxidants resulted in an insignificant increase in TBARs:4.5 +/-1.5 vs.16.2 +/-3.9 nmol/g protein, p=0.0625,and 4.0 +/-0.8 vs.7.6 +/-4.0 for freshly isolated and cultured cells, respectively. Oxidative stress itself did not increase cytotoxicity. CONCLUSIONS: Type II AECs are not resistant to oxidative stress. We cannot, however, explain why cells with evidence of lipid peroxidation do not show increased cytotoxicity. The toxicity of ATZ is not related to oxidative cell damage. In cells exposed to oxidants, TBARS may fur-ther increase when catalase is inhibited, which suggests an important protective role for catalase.     

Small CD4+8+TCRlow thymocytes contain precursors of mature T cells

To evaluate directly the developmental potential of cortical CD4⁺8⁺ thymocytes, highly purified populations of small, nondividing CD4⁺8⁺TCR^low and large, dividing CD4⁺8⁺TCR^high thymocytes from H-2^d mice expressing a transgenic T cell receptor restricted by H-2D^b (major histocompatibility complex class I) molecules were transferred into the thymus of normal, nonirradiated H-2^b recipient mice. The results show that both populations generate CD4^?8⁺ thymocytes under these conditions, thus providing conclusive evidence that small cortical thymocytes do not represent a “dead end” but an important intermediate stage in T cell development.     

Effectiveness of divergent selection for open-field activity in rabbits and correlated response for body weight and fertility

Two lines deriving from the same rabbit stock were selected for 8 generations for high (H) or low (L) locomotor activity score in the open field (OFS). The divergent selection was most effective up to the 3rd generation in the H line and up to the 4th generation in the L line. In further generations a decrease of OFS in the H line and a floor effect (OFS = 0) in the L line were observed. The mean OFS increased significantly in consecutive trials in the H line, whereas this increase was non-significant in the L line. There was a negative and very high correlation between the latency to enter the open field and the OFS (–0.95 and –0.98 for the H and L line, respectively). The realized heritability of the OFS was 0.46 and 0.23 in generations 0–3 within the L and H line, respectively, and 0.44 and –0.06 in generations 0–8. As calculated on the basis of divergent selection, the heritability was 0.31 and 0.15 for generations 0–3 and 0–8, respectively. The L rabbits were heavier shortly before (4th wk, P < 0.001) and after (8th wk, P < 0.01) weaning, than those of the H line, whereas the H rabbits grew faster (P < 0.05) between the 4th and 20th wk of age. There was a tendency for decreasing weight gains in consecutive generations. Generally, a lower percentage of H females delivered litters than those of the L line, but this was due to a very low percentage of such females in the 3rd and 6th generations. It can be assumed that H and L lines represent different, i.e., active and passive, coping strategies. These lines of rabbits offer increased possibilities for physiologically and ethologically oriented studies, e.g., on the welfare of caged animals.