Design and synthesis of de novo cytotoxic alkaloids by mimicking the bioactive conformation of paclitaxel

Novel paclitaxel-mimicking alkaloids were designed and synthesized based on a bioactive conformation of paclitaxel, that is, REDOR-Taxol. The alkaloid 2 bearing a 5-7-6 tricyclic scaffold mimics REDOR-Taxol best among the compounds designed and was found to be the most potent compound against several drug-sensitive and drug-resistant human cancer cell lines. MD simulation study on the paclitaxel mimics 1 and 2 as well as REDOR-Taxol bound to the 1JFF tubulin structure was quite informative to evaluate the level of mimicking. The MD simulation study clearly distinguishes the 5-6-6 and 5-7-6 tricyclic scaffolds, and also shows substantial difference in the conformational stability of the tubulin-bound structures between 2 and REDOR-Taxol. The latter may account for the large difference in potency, and provides critical information for possible improvement in the future design of paclitaxel mimics.     

MITOGEN-ACTIVATED PROTEIN KINASE 4 impacts leaf development,temperature, and stomatal movement in hybrid aspen

Stomatal movement and density influence plant water use efficiency and thus biomass production. Studies in model plants within controlled environments suggest MITOGEN-ACTIVATED PROTEIN KINASE 4 (MPK4) may be crucial for stomatal regulation. We present functional analysis of MPK4 for hybrid aspen (Populus tremula × tremuloides) grown under natural field conditions for several seasons. We provide evidence of the role of MPK4 in the genetic and environmental regulation of stomatal formation, differentiation, signaling, and function; control of the photosynthetic and thermal status of leaves; and growth and acclimation responses. The long-term acclimation manifested as variations in stomatal density and distribution. Short-term acclimation responses were derived from changes in the stomatal aperture. MPK4 localized in the cytoplasm of guard cells (GCs) was a positive regulator of abscisic acid (ABA)-dependent stomatal closure and nitric oxide metabolism in the ABA-dependent pathways, while to a lesser extent, it was involved in ABA-induced hydrogen peroxide accumulation. MPK4 also affected the stomatal aperture through deregulation of microtubule patterns and cell wall structure and composition, including via pectin methyl-esterification, and extensin levels in the GC wall. Deregulation of leaf anatomy (cell compaction) and stomatal movement, together with increased light energy absorption, resulted in altered leaf temperature, photosynthesis, cell death, and biomass accumulation in mpk4 transgenic plants. Divergence between absorbed energy and assimilated energy is a bottleneck, and MPK4 can participate in the control of energy dissipation (thermal effects). Furthermore, MPK4 can participate in balancing the photosynthetic energy distribution via its effective use in growth or redirection to acclimation/defense responses.

MITOGEN-ACTIVATED PROTEIN KINASE 4 plays a multilevel role in stomatal formation, function, and signaling in the photosynthetic and thermal status of leaves and in growth and acclimation responses.     

Assessment of the effect of alpha-galactosides injected during embryogenesis on selected chicken traits

The effect of different doses of alpha-galactoside (RFOs) preparations from Pisum sativum L. cv. Opal, injected into eggs during embryogenesis, on maintaining a high number of bifidobacteria, selected chicken broiler traits and the lipoprotein level of blood were studied. Two independent experiments were conducted. In the first, Ringer water solution containing 1.763 mg/egg of fructooligosaccharides (FOS) (I group), 2.1158 mg of pea RFO preparation containing 20% sucrose (II group) and 0.4232 mg of sucrose (III group) were injected into Hubbard broiler breeder eggs containing 12-day old embryos. Only Ringer water solution was applied to the eggs of the control group (IV group). The number of bifidobacteria determined in faeces of two-day old chicken of groups I and II was significantly higher in comparison with the sucrose and control groups. The high level ofbifidobacteria of groups I and II was maintained during 6 weeks. The dose of both preparations had no influence on the body weight, carcass, breast muscle, leg and abdominal fat ratio, total cholesterol, HDL and LDL serum concentrations. Broiler mortality and breast muscle cholesterol concentration was highest (P < 0.05) for the control group. On the other hand, the European Production Index, as well as serum triglycerides, were the lowest for this group. The second experiment was performed on Hybro G chicken breeder eggs. 0.69, 3.43 and 6.87 mg/egg of pea RFO preparation doses containing 20% sucrose were injected into the experimental groups. The number of bifidobacteria in the caecum and selected meat traits of broilers were determined. The results of this experiment confirmed that RFO injection in ovo causes the long-time maintenance of a high level ofbifidobacteria. The dose of the preparations does not have any effect on the selected broiler meat traits, except that the highest dose increases the percent of carcase in body weight. However, this dose reduced the hatchability of the treated embryos.     

Interrelationships of platelet-derived growth factor isoform-induced changes in c-fos expression, intracellular free calcium, and mitogenesis

Both increases in c-fos proto-oncogene expression and intracellular free calcium ([Ca2+]i) have been implicated as necessary components of the signal transduction pathway by which platelet-derived growth factor (PDGF) stimulates DNA synthesis in cultured BALB/c3T3 fibroblasts. To determine the interrelationship between PDGF-induced increases in c-fos proto-oncogene expression and [Ca2+]i, purified, recombinant BB and AA homodimeric isoforms of PDGF were used to evaluate the dose-response relationships and mechanisms of growth factor-induced changes in these two parameters as well as DNA synthesis. Concentration-dependent increases in [Ca2+]i, c-fos expression, and [3H]thymidine incorporation were observed with both BB and AA PDGF isoforms. BB PDGF was consistently more potent and efficacious than the AA isoform in eliciting a given response. The [Ca2+]i dependency of PDGF-induced increases in c-fos expression and DNA synthesis was determined by pretreatment of cells with agents that inhibit increases in [Ca2+]i: BAPTA, Quin-2, and TMB-8. Under these conditions, PDGF-induced DNA synthesis was blocked, whereas c-fos expression was enhanced. Conversely, in cells made deficient in protein kinase C (PKC) activity by prolonged treatment with phorbol ester, BB and AA PDGF-induced c-fos expression was inhibited by 75-80%, while PDGF-induced increases in [Ca2+]i and DNA synthesis were unaffected or enhanced. Additionally, the PKC-independent component of PDGF-stimulated c-fos expression was found to be independent of increases in [Ca2+]i. These data suggest that 1) both BB and AA PDGF isoforms elicit alterations in [Ca2+]i and c-fos proto-oncogene expression through the same or similar mechanisms in BALB/c3T3 fibroblasts, 2) PDGF-stimulated increases in [Ca2+]i are not required for c-fos expression, and 3) distinct pathways regulate PDGF-induced c-fos expression and mitogenesis, with c-fos expression being substantially PKC-dependent yet [Ca2+]i-independent, while mitogenesis is [Ca2+]i-dependent yet PKC-independent.     

Genetic analysis of resistance to Puccinia striiformis f.sp. tritici in cv. Aflak at adult plant stage

In order to investigate heritability and gene action for yellow rust resistance in wheat, a resistance yellow rust cultivar Aflak was crossed to susceptible cultivar Avocet‘s’. Parents, F₁, F₂ and F₃ generations were cultured according to randomised complete block design with two replications in the research station of Gharakhil, Iran. Parents and other generations were inoculated with 70E0A+ race. Traits including severity and infection type were recorded and then coefficient of infection was calculated. For this trait, generations mean and variance analysis were performed and results showed that there were significant differences among generations for coefficient of infection. Results showed that in addition to additive and dominance effects, at least one kind of epistasis interaction (additive × additive) control this trait. Although additive and dominance effects control this trait, but with attention to generations variance analysis, the results showed that additive variance had important role to control this trait.     

Fine needle aspiration cytology of renal infarcts. Cytomorphologic findings and potential diagnostic pitfalls in two cases

The fine needle aspiration (FNA) cytologic features of two cases of renal infarction are presented. Both patients did not have a classic clinical history for infarction, and the radiologic findings were suggestive of neoplasia. In one of our cases, necrotic glomeruli and tubules were present, which suggested the correct diagnosis of renal infarction and permitted appropriate early treatment. In the other case, groups of atypical renal tubular cells undergoing repair secondary to the infarction was misinterpreted as renal cell carcinoma. This case illustrates that renal infarction, like pulmonary infarction, can be a potential pitfall for a false-positive cytologic diagnosis of malignancy in FNA biopsy. A conservative approach is warranted when there is scanty cellularity and atypical cells having features of a repairlike reaction are present.