The activity of diguanidino and 'reversed' diamidino 2,5-diarylfurans versus Trypanosoma cruzi and Leishmania donovani

The in vitro activity of 20 dicationic molecules containing either diguanidino or reversed amidine cationic groups were evaluated versus Trypanosoma cruzi and Leishmania donovani. The most active compounds were in the reversed amidine series and six exhibited IC(50) values of less than 1 micro mol versus T. cruzi and five gave similar values versus L. donovani.     

Support for a meiotic recombination initiation complex: interactions among Rec102p,Rec104p,and Spo11p

Initiation of meiotic recombination in the yeast Saccharomyces cerevisiae requires at least 10 gene products. The initiation event creates double-strand breaks, which are then processed by other recombination enzymes. A variety of classical observations, such as the existence of recombination nodules, have suggested that the proteins catalyzing recombination form a complex. A variety of lines of evidence indicate that Rad50p, Mre11p, and Xrs2p interact, and genetic data suggesting interactions between Rec102p and Rec104p have been reported. It has recently been shown that Spo11p coimmunoprecipitates with Rec102p in meiosis as well. In this paper, we provide genetic and biochemical evidence that the meiosis-specific proteins Rec102p, Rec104p, and Spo11p all interact with each other in meiosis. Furthermore, we demonstrate that the interaction between Rec102p and Spo11p does not require Rec104p. Likewise, the interaction between Rec104p and Rec102p does not require Spo11p, although Spo11p may stabilize that association. The interactions suggest that Spo11p, Rec102p, and Rec104p may form a trimeric complex during the initiation of recombination.     

Optimization of yield in magnetic cell separations using nickel nanowires of different lengths

Ferromagnetic nanowires are shown to perform both high yield and high purity single-step cell separations on cultures of NIH-3T3 mouse fibroblast cells. The nanowires are made by electrochemical deposition in nanoporous templates, permitting detailed control of their chemical and physical properties. When added to fibroblast cell cultures, the nanowires are internalized by the cells via the integrin-mediated adhesion pathway. The effectiveness of magnetic cell separations using Ni nanowires 350 nm in diameter and 5-35 micrometers long in field gradients of 40 T/m was compared to commercially available superparamagnetic beads. The percent yield of the separated populations is found to be optimized when the length of the nanowire is matched to the diameter of the cells in the culture. Magnetic cell separations performed under these conditions achieve 80% purity and 85% yield, a 4-fold increase over the beads. This effect is shown to be robust when the diameter of the cell is changed within the same cell line using mitomycin-C.     

Effects of an n-3-deficient diet on brain, retina, and liver fatty acyl composition in artificially reared rats

Rat pups born to dams fed a diet with 3.1% of total fatty acids as alpha-linolenic acid (LNA) were fed, using an artificial rearing system, either an n-3-deficient (n-3-Def) or an n-3-adequate (n-3-Adq) diet. Both diets contained 17.1% linoleic acid, but the n-3-Adq diet also contained 3.1% LNA. The percentage of brain docosahexaenoic acid (DHA) continuously decreased (71%) with time over the 29 days of the experiment, with concomitant increases in docosapentaenoic acid (DPAn-6). In the retina, the percentage of DHA rose in the n-3-Adq group, with an apparent increased rate around the time of eye opening. However, there was a flat curve for the percentage of DHA in the n-3-Def group and a rising DPAn-6 with time. Liver DHA was highest at the time of birth in the n-3-Adq group but fell off somewhat over the course of 29 days. This decrease was more pronounced in the n-3-Def group, and the DPAn-6 rose considerably during the second half of the experiment. This method presents a first-generation model for n-3 deficiency that is more similar to the case of human nutrition than is the commonly employed two-generation model.     

Computational studies of the effects of myocardial blood flow reductions on cardiac metabolism

Background  

A computational model of myocardial energy metabolism was used to assess the metabolic responses to normal and reduced myocardial blood flow. The goal was to examine to what extent glycolysis and lactate formation are controlled by the supply of glycolytic substrate and/or the cellular redox (NADH/NAD⁺) and phosphorylation (ATP/ADP) states.     

Evaluation of loxoprofen and its alcohol metabolites for potency and selectivity of inhibition of cyclooxygenase-2

Loxoprofen, its trans-alcohol and cis-alcohol metabolites were evaluated for selectivity of inhibition of COX-2 over COX-1. The (2S,1'R,2'S)-trans-alcohol derivative was found to be the most active metabolite and to be a potent and nonselective inhibitor of COX-2 and COX-1 in both enzyme and human whole blood assays.     

Biomechanical attributes of lunging activities for older adults

The purpose of this study was to characterize the mechanical demands of the lower-extremity musculature during the standing forward lunge (FL) and the standing lateral lunge (LL) exercises performed by older adults. Twenty healthy older adults (9 men, 11 women, mean age 75.0 +/- 4.4 years) performed FL and LL while instrumented for biomechanical analysis. Lower-extremity net joint moments, powers, impulse, and mechanical energy expenditure were determined using standard inverse dynamics techniques. The FL preferentially targeted the hip extensors, producing a greater flexion angle (12.8%), peak joint moment (13.6%), joint power (56.5%), and mechanical energy expenditure (25.1%). Conversely, LL targeted the ankle plantar flexors, producing greater dorsiflexion angles (19.3%), joint moments (40.9%), impulse (87.0%), and mechanical energy expenditure (61.1%). Kinetic differences at the knee were less consistent. Fitness professionals may use this information to better match the biomechanical attributes of FL and LL activities with the needs of the trainee.     

Resistance to TNF-induced cytotoxicity correlates with an abnormal cleavage of cytosolic phospholipase A2

To investigate the mechanism underlying the absence of arachidonic acid (AA) release by TNF in TNF-resistant cells, we first performed comparative analysis of phospholipid pools in both TNF-sensitive (MCF7) and their equivalent resistant cells (C1001). Quantification and incorporation studies of [(3)H]AA indicated that TNF-resistant cells were not depleted in AA. Furthermore, distribution of this fatty acid in different phospholipid pools was similar in both sensitive cells and their resistant counterparts, ruling out a defect in phospholipid pools. Since phospholipase A(2) (PLA(2)) are the main enzymes releasing free AA, we investigated their relative contribution in the acquisition of cell resistance to TNF-induced cell death and AA release. For this purpose, we used two PLA(2) inhibitors, methylarachidonyl fluorophosphate (MAFP) and bromoenol lactone (BEL), which selectively and irreversibly inhibit the cytosolic PLA(2) (cPLA(2)) and the Ca(2+)-independent PLA(2), respectively. Although a significant inhibitory effect of MAFP on both TNF-induced AA release and PLA(2) activity in MCF7 was observed, BEL had no effect. The inhibitory effect of MAFP on cPLA(2) activity correlated with an inhibition of TNF-induced cell death. Western blot analysis revealed that TNF induced a differential cleavage of cPLA(2) in TNF-sensitive vs TNF-resistant cells. Although the p70 (70-kDa) form of cPLA(2) was specifically increased in TNF-sensitive cells, a cleaved form, p50 (50 kDa), was selectively observed in TNF-resistant C1001 cells in the presence or absence of TNF. These findings suggest that the acquisition of cell resistance to this cytokine may involve an abnormal cPLA(2) cleavage.     

Behavioral deficits associated with dietary induction of decreased brain docosahexaenoic acid concentration

Docosahexaenoic acid (DHA), an n-3 fatty acid, is rapidly deposited during the period of rapid brain development. The influence of n-3 fatty acid deficiency on learning performance in adult rats over two generations was investigated. Rats were fed either an n-3 fatty acid-adequate (n-3 Adq) or -deficient (n-3 Def) diet for three generations (F1-F3). Levels of total brain n-3 fatty acids were reduced in the n-3 Def group by 83 and 87% in the F2 and F3 generations, respectively. In the Morris water maze, the n-3 Def group showed a longer escape latency and delayed acquisition of this task compared with the n-3 Adq group in both generations. The acquisition and memory levels of the n-3 Def group in the F3 generation seemed to be lower than that of the F2 generation. The 22:5n-6/22:6n-3 ratio in the frontal cortex and dams' milk was markedly increased in the n-3 Def group, and this ratio was significantly higher in the F3 generation compared with the F2 generation. These results suggest that learning and cognitive behavior are related to brain DHA status, which, in turn, is related to the levels of the milk/dietary n-3 fatty acids.