Patient-specific MRI-based 3D FSI RV/LV/patch models for pulmonary valve replacement surgery and patch optimization

A patient-specific right/left ventricle and patch (RV/LV/patch) combination model with fluid-structure interactions (FSIs) was introduced to evaluate and optimize human pulmonary valve replacement/insertion (PVR) surgical procedure and patch design. Cardiac magnetic resonance (CMR) imaging studies were performed to acquire ventricle geometry, flow velocity, and flow rate for healthy volunteers and patients needing RV remodeling and PVR before and after scheduled surgeries. CMR-based RV/LV/patch FSI models were constructed to perform mechanical analysis and assess RV cardiac functions. Both pre- and postoperation CMR data were used to adjust and validate the model so that predicted RV volumes reached good agreement with CMR measurements (error <3%). Two RV/LV/patch models were made based on preoperation data to evaluate and compare two PVR surgical procedures: (i) conventional patch with little or no scar tissue trimming, and (ii) small patch with aggressive scar trimming and RV volume reduction. Our modeling results indicated that (a) patient-specific CMR-based computational modeling can provide accurate assessment of RV cardiac functions, and (b) PVR with a smaller patch and more aggressive scar removal led to reduced stress/strain conditions in the patch area and may lead to improved recovery of RV functions. More patient studies are needed to validate our findings.     

Alternate AChE-R variants facilitate cellular metabolic activity and resistance to genotoxic stress through enolase and RACK1 interactions

Tumorogenic transformation is a multifaceted cellular process involving combinatorial protein-protein interactions that modulate different cellular functions. Here, we report apparent involvement in two independent tumorogenic processes by distinct partner protein interactions of the stress-induced acetylcholinesterase AChE-R and N-AChE-R variants. Human testicular tumors showed elevated levels of N-terminally extended N-AChE-R compared with healthy tissue, indicating alternate promoter usage in the transformed cells. Two-hybrid screens demonstrate that the C-terminus common to both N-AChE-R and AChE-R interacts either with the glycolytic enzyme enolase or with the scaffold protein RACK1. In vitro, the AChE-R C-terminal peptide ARP elevated enolase's activity by 12%, suggesting physiological relevance for this interaction. Correspondingly, CHO cells expressing either human AChE-R or N-AChE-R but not AChE-S showed a 25% increase in cellular ATP levels, indicating metabolic significance for this upregulation of enolase activity. ATP levels could be reduced by AChE-targeted siRNA in CHO cells expressing AChE-R but not AChE-S, attributing this elevation to the AChE-R C-terminus. Additionally, transfected CHO cells expressing AChE-R but not N-AChE-R showed resistance to up to 60muM of the common chemotherapeutic agent, cis-platinum, indicating AChE-R involvement in another molecular pathway. cis-Platinum elevates the expression of the apoptosis-regulator p53-like protein, p73, which is inactivated by interaction with the scaffold protein RACK1. In co-transfected cells, AChE-R competed with endogenous RACK1 for p73 interaction. Moreover, AChE-R-transfected CHO cells presented higher levels than control cells of the pro-apoptotic TAp73 as well as the anti-apoptotic dominant negative DeltaNp73 protein, leading to an overall decrease in the proportion of pro-apoptotic p73. Together, these findings are compatible with the hypothesis that in cancer cells, both AChE-R and N-AChE-R elevate cellular ATP levels and that AChE-R modifies p73 gene expression by facilitating two independent cellular pathways, thus conferring both a selective metabolic advantage and a genotoxic resistance.     

Response of Spinach Leaves (Spinacia oleracea L.) to Ozone Measured by Gas Exchange,Chlorophyll a Fluorescence,Antioxidant Systems,and Lipid Peroxidation

Spinach (Spinacia oleracea L. cv. Clermont) leaves grown in open-top chambers and exposed to three different concentrations of ozone were measured for gas exchange, chlorophyll a fluorescence, antioxidant systems, and lipid peroxidation at the end of growing season. High O₃ concentration reduced F_v/F_m, indicating that the efficiency in the energy conversion of photosystem 2 (PS2) was altered. The rate of non-cyclic electron transport rate and the capacity to reduce the quinone pool were also affected. The development of non-photochemical quenching was not high enough to decrease the photon excess in the PS2. The limitation of photosynthetic activity was probably correlated with stomata closure and with an increase in intercellular CO₂ concentration. Under oxidative stress, superoxide dismutase (SOD) activity was stimulated in parallel with lipid peroxidation. We did not find any differences in the ascorbate (AsA) pool and ascorbate peroxidase (APX) or glutathione reductase (GR) activities between air qualities. Small, but similar responses were observed in spinach leaves exposed to ambient ozone concentration.     

In vitro selection for salt tolerance in crop plants: Theoretical and practical considerations

Summary In recent years attempts have been made to supplement traditional breeding for the production of salt-tolerant plants with variability existing in cell culture. The potential causes suggested as an explanation for the limited success of the in vitro approach include: a) lack, or loss during selection, of regeneration capability; b) the development of epigenetically adapted cells; c) lack of correlation between the mechanisms of tolerance operating in cultured cells and mechanisms that operate in cells in the intact plant; and d) multigenicity of salt tolerance. The recent successful production of healthy, fertile, and genetically stable salt-tolerant regenerants from cells obtained from highly morphogenic explants which are selected early in culture (using one-step or short-term strategies) for salt tolerance, together with the demonstration that salt-sensitive plants can become tolerant by mutations in one or few genes, suggest that some of the potential limitations can be overcome and that some of them may not exist at all.     

Epitopia: a web-server for predicting B-cell epitopes

Background  

Detecting candidate B-cell epitopes in a protein is a basic and fundamental step in many immunological applications. Due to the impracticality of experimental approaches to systematically scan the entire protein, a computational tool that predicts the most probable epitope regions is desirable.     

Global maximization of Jatropha oil production under semi‐arid conditions by balancing vegetative growth with reproductive capacity

Jatropha curcas L. is a drought tolerant crop that is globally cultivated under semi‐arid conditions as a biodiesel feedstock. Despite its great potential, however, many projects failed to reach commercially viable seed and oil yields. The aim of the study was to provide globally applicable solutions for maximization of Jatropha oil production under semi‐arid conditions. Under extremely low irrigation (10% of potential evapotranspiration; ETp), fruit production was very low and a surprisingly significant portion of the fruits delayed their maturity up to six months post‐bloom. Increasing irrigation to mid‐level (60% ETp) significantly elevated fruit production and speeded up the ripening rate, whereas further increasing irrigation to a higher level (90% ETp) decreased seed and oil yields, probably due to the increased investment in vegetative growth. Nevertheless, maximal seed and oil yields at 60% ETp remained far below targeted yields. Coupling irrigation at 60% ETp, with induction of vegetative arrest, by soil application of a commercial gibberellin synthesis inhibitor, brought forward the second bloom period by two months, reduced vegetative growth, promoted floral production and significantly enhanced reproductive capacity by more than doubling oil production. The results show that under semi‐arid conditions, commercially viable seed and oil yields of Jatropha can be achieved by carefully balancing vegetative growth with reproductive capacity through the combined application of optimal irrigation regimes and induced vegetative arrest.     

Localization of the Gene for Thiamine-Responsive Megaloblastic Anemia Syndrome, on the Long Arm of Chromosome 1, by Homozygosity Mapping

Thiamine-responsive megaloblastic anemia, also known as "TRMA" or "Rogers syndrome," is an early-onset autosomal recessive disorder defined by the occurrence of megaloblastic anemia, diabetes mellitus, and sensorineural deafness, responding in varying degrees to thiamine treatment. On the basis of a linkage analysis of affected families of Alaskan and of Italian origin, we found, using homozygosity mapping, that the TRMA-syndrome gene maps to a region on chromosome 1q23.2-23.3 (maximum LOD score of 3.7 for D1S1679). By use of additional consanguineous kindreds of Israeli-Arab origin, the putative disease-gene interval also has been confirmed and narrowed, suggesting genetic homogeneity. Linkage analysis generated the highest combined LOD-score value, 8.1 at a recombination fraction of 0, with marker D1S2799. Haplotype analysis and recombination events narrowed the TRMA locus to a 16-cM region between markers D1S194 and D1S2786. Several heterozygote parents had diabetes mellitus, deafness, or megaloblastic anemia, which raised the possibility that mutations at this locus predispose carriers in general to these manifestations. Characterization of the metabolic defect of TRMA may shed light on the role of thiamine deficiency in such common diseases.