Synthesis and antimicrobial activity of 2-fluorophenyl-4,6-disubstituted [1,3,5]triazines

A series of 2-fluorophenyl-4,6-disubstituted [1,3,5]triazines (1) and (2) were synthesized and evaluated for their antimicrobial activity against three representative gram-positive bacteria and two fungi. The structure–activity relationship (SAR) demonstrates that the 3- or 4-fluorophenyl component attached directly to the triazine ring was essential for activity. Of these compounds, 14, 15, and 25 demonstrated significant activity against all selected organisms compared to control. These compounds were generally nontoxic and may prove useful as antimicrobial agents.     

Phosphate and ADP Differently Inhibit Coordinated Smooth Muscle Myosin Groups

Actin filaments propelled in vitro by groups of skeletal muscle myosin motors exhibit distinct phases of active sliding or arrest, whose occurrence depends on actin length (L) within a range of up to 1.0 μm. Smooth muscle myosin filaments are exponentially distributed with ≈150 nm average length in vivo—suggesting relevance of the L-dependence of myosin group kinetics. Here, we found L-dependent actin arrest and sliding in in vitro motility assays of smooth muscle myosin. We perturbed individual myosin kinetics with varying, physiological concentrations of phosphate (P_i, release associated with main power stroke) and adenosine diphosphate (ADP, release associated with minor mechanical step). Adenosine triphosphate was kept constant at physiological concentration. Increasing [P_i] lowered the fraction of time for which actin was actively sliding, reflected in reduced average sliding velocity (ν) and motile fraction (f_mot, fraction of time that filaments are moving); increasing [ADP] increased the fraction of time actively sliding and reduced the velocity while sliding, reflected in reduced ν and increased f_mot. We introduced specific P_i and ADP effects on individual myosin kinetics into our recently developed mathematical model of actin propulsion by myosin groups. Simulations matched our experimental observations and described the inhibition of myosin group kinetics. At low [P_i] and [ADP], actin arrest and sliding were reflected by two distinct chemical states of the myosin group. Upon [P_i] increase, the probability of the active state decreased; upon [ADP] increase, the probability of the active state increased, but the active state became increasingly similar to the arrested state.     

Renin inhibitors for the treatment of hypertension: design and optimization of a novel series of tertiary alcohol-bearing piperidines

The design and optimization of a novel series of renin inhibitor is described herein. Strategically, by committing the necessary resources to the development of synthetic sequences and scaffolds that were most amenable for late stage structural diversification, even as the focus of the SAR campaign moved from one end of the molecule to another, highly potent renin inhibitors could be rapidly identified and profiled.     

Melanocortin-4 receptors expressed by cholinergic neurons regulate energy balance and glucose homeostasis

Melanocortin-4 receptor (MC4R) mutations cause dysregulation of energy balance and hyperinsulinemia. We have used mouse models to study the physiological roles of extrahypothalamic MC4Rs. Re-expression of MC4Rs in cholinergic neurons (ChAT-Cre, loxTB MC4R mice) modestly reduced body weight gain without altering food intake and was sufficient to normalize energy expenditure and attenuate hyperglycemia and hyperinsulinemia. In contrast, restoration of MC4R expression in brainstem neurons including those in the dorsal motor nucleus of the vagus (Phox2b-Cre, loxTB MC4R mice) was sufficient to attenuate hyperinsulinemia, while the hyperglycemia and energy balance were not normalized. Additionally, hepatic insulin action and insulin-mediated suppression of hepatic glucose production were improved in ChAT-Cre, loxTB MC4R mice. These findings suggest that MC4Rs expressed by cholinergic neurons regulate energy expenditure and hepatic glucose production. Our results also provide further evidence of the dissociation in pathways mediating the effects of melanocortins on energy balance and glucose homeostasis.     

Modeling the oscillation dynamics of activated airway smooth muscle strips

When strips of activated airway smooth muscle are stretched cyclically, they exhibit force-length loops that vary substantially in both position and shape with the amplitude and frequency of the stretch. This behavior has recently been ascribed to a dynamic interaction between the imposed stretch and the number of actin-myosin interactions in the muscle. However, it is well known that the passive rheological properties of smooth muscle have a major influence on its mechanical properties. We therefore hypothesized that these rheological properties play a significant role in the force-length dynamics of activated smooth muscle. To test the plausibility of this hypothesis, we developed a model of the smooth muscle strip consisting of a force generator in series with an elastic component. Realistic steady-state force-length loops are predicted by the model when the force generator obeys a hyperbolic force-velocity relationship, the series elastic component is highly nonlinear, and both elastic stiffness and force generation are adjusted so that peak loop force equals isometric force. We conclude that the dynamic behavior of airway smooth muscle can be ascribed in large part to an interaction between connective tissue rheology and the force-velocity behavior of contractile proteins.     

Synthesis of enzymatically active human alpha-L-iduronidase in Arabidopsis cgl (complex glycan-deficient) seeds

As an initial step to develop plants as systems to produce enzymes for the treatment of lysosomal storage disorders, Arabidopsis thaliana wild-type (Col-0) plants were transformed with a construct to express human alpha-l-iduronidase (IDUA; EC 3.2.1.76) in seeds using the promoter and other regulatory sequences of the Phaseolus vulgaris arcelin 5-I gene. IDUA protein was easily detected on Western blots of extracts from the T(2) seeds, and extracts contained IDUA activity as high as 2.9 nmol 4-methylumbelliferone (4 MU)/min/mg total soluble protein (TSP), corresponding to approximately 0.06 microg IDUA/mg TSP. The purified protein reacted with an antibody specific for xylose-containing plant complex glycans, indicating its transit through the Golgi complex. In an attempt to avoid maturation of the N-linked glycans of IDUA, the same IDUA transgene was introduced into the Arabidopsis cgl background, which is deficient in the activity of N-acetylglucosaminyl transferase I (EC 2.4.1.101), the first enzyme in the pathway of complex glycan biosynthesis. IDUA activity and protein levels were significantly higher in transgenic cgl vs. wild-type seeds (e.g. maximum levels were 820 nmol 4 MU/min/mg TSP, or 18 microg IDUA/mg TSP). Affinity-purified IDUA derived from cgl mutant seeds showed a markedly reduced reaction with the antibody specific for plant complex glycans, despite transit of the protein to the apoplast. Furthermore, gel mobility changes indicated that a greater proportion of its N-linked glycans were susceptible to digestion by Streptomyces endoglycosidase H, as compared to IDUA derived from seeds of wild-type Arabidopsis plants. The combined results indicate that IDUA produced in cgl mutant seeds contains glycans primarily in the high-mannose form. This work clearly supports the viability of using plants for the production of human therapeutics with high-mannose glycans.     

The many faces of ubiquitinated histone H2A: insights from the DUBs

Increasing knowledge on the cell cycle deregulations in cancers has promoted the introduction of phytochemicals, which can either modulate signaling pathways leading to cell cycle regulation or directly alter cell cycle regulatory molecules, in cancer therapy. Most human malignancies are driven by chromosomal translocations or other genetic alterations that directly affect the function of critical cell cycle proteins such as cyclins as well as tumor suppressors, e.g., p53. In this respect, cell cycle regulation and its modulation by curcumin are gaining widespread attention in recent years. Extensive research has addressed the chemotherapeutic potential of curcumin (diferuloylmethane), a relatively non-toxic plant derived polyphenol. The mechanisms implicated are diverse and appear to involve a combination of cell signaling pathways at multiple levels. In the present review we discuss how alterations in the cell cycle control contribute to the malignant transformation and provide an overview of how curcumin targets cell cycle regulatory molecules to assert anti-proliferative and/or apoptotic effects in cancer cells. The purpose of the current article is to present an appraisal of the current level of knowledge regarding the potential of curcumin as an agent for the chemoprevention of cancer via an understanding of its mechanism of action at the level of cell cycle regulation. Taken together, this review seeks to summarize the unique properties of curcumin that may be exploited for successful clinical cancer prevention.     

苹果园光能截获率的数学模型

应用气象学原理推导了不同纬度、不同栽植行向、不同树形的苹果园光能截获率的数学模型,给出在保证树冠基部外围日照时间大于25％总日照时间的条件下,生长季中充分截获光能的最佳树形、行距、冠高、冠径的优化组合方案。实例分析表明,计算结果与专家经验基本一致。本研究为果园合理栽植,充分利用光能,合理整形修剪提供理论依据与参考方案。