Design, synthesis and biological characterization of novel inhibitors of CD38

Human CD38 is a novel multi-functional protein that acts not only as an antigen for B-lymphocyte activation, but also as an enzyme catalyzing the synthesis of a Ca 2+ messenger molecule, cyclic ADP-ribose, from NAD +. It is well established that this novel Ca 2+ signaling enzyme is responsible for regulating a wide range of physiological functions. Based on the crystal structure of the CD38/NAD + complex, we synthesized a series of simplified N-substituted nicotinamide derivatives (Compound1-14). A number of these compounds exhibited moderate inhibition of the NAD + utilizing activity of CD38, with Compound4 showing the highest potency. The crystal structure of CD38/Compound4 complex and computer simulation of Compound7 docking to CD38 show a significant role of the nicotinamide moiety and the distal aromatic group of the compounds for substrate recognition by the active site of CD38. Biologically, we showed that both Compounds4 and 7 effectively relaxed the agonist-induced contraction of muscle preparations from rats and guinea pigs. This study is a rational design of inhibitors for CD38 that exhibit important physiological effects, and can serve as a model for future drug development. © 2011 The Royal Society of Chemistry.postprin

The effects of an extensive exercise programme on the progression of Mild Cognitive Impairment (MCI): study protocol for a randomised controlled trial

Background Exercise interventions to prevent dementia and delay cognitive decline have gained considerable attention in recent years. Human and animal studies have demonstrated that regular physical activity targets brain function by increasing cognitive reserve. There is also evidence of structural changes caused by exercise in preventing or delaying the genesis of neurodegeneration. Although initial studies indicate enhanced cognitive performance in patients with mild cognitive impairment (MCI) following an exercise intervention, little is known about the effect of an extensive, controlled and regular exercise regimen on the neuropathology of patients with MCI. This study aims to determine the effects of an extensive exercise programme on the progression of MCI. Methods/design This randomised controlled clinical intervention study will take place across three European sites. Seventy-five previously sedentary patients with a clinical diagnosis of MCI will be recruited at each site. Participants will be randomised to one of three groups. One group will receive a standardised 1-year extensive aerobic exercise intervention (3 units of 45 min/week). The second group will complete stretching and toning (non-aerobic) exercise (3 units of 45 min/week) and the third group will act as the control group. Change in all outcomes will be measured at baseline (T0), after six months (T1) and after 12 months (T2). The primary outcome, cognitive performance, will be determined by a neuropsychological test battery (CogState battery, Trail Making Test and Verbal fluency). Secondary outcomes include Montreal Cognitive Assessment (MoCA), cardiovascular fitness, physical activity, structural changes of the brain, quality of life measures and measures of frailty. Furthermore, outcome variables will be related to genetic variations on genes related to neurogenesis and epigenetic changes in these genes caused by the exercise intervention programme. Discussion The results will add new insights into the prevailing notion that exercise may slow the rate of cognitive decline in MCI

Monitoring cytosolic calcium in the dinoflagellate Crypthecodinium cohnii with calcium orange-AM

Calcium plays several important roles in the signal transduction pathways of dinoflagellates. We describe here the development of calcium orange-AM as an intracellular calcium reporter for the heterotrophic dinoflagellate Crypthecodinium cohnii. We demonstrated with confocal microscopy that by restricting the incubation period to 3045 min, no compartmentalization of the dye occurs in the mitochondria or endoplasmic reticulum. The dye fluorescence responded well to the effects of calcium ionophores and calcium chelators. By calibrating the dye with known calcium concentrations, we determined the intracellular calcium concentration of C. cohnii to be 158 +/- 56 nM, which rose to about 550 nM upon mechanical stimulation

cAMP in the cell cycle of the dinoflagellate Crypthecodinium cohnii (Dinophyta)

The second messenger cAMP is a key regulator of growth in many cells. Previous studies showed that cAMP could reverse the growth inhibition of indoleamines in the dinoflagellate Crypthecodinium cohnii Biecheler, Zn the present study, we measured the level of intracellular cAMP during the cell cycle of C. cohnii. cAMP peaked during the G(1) phase and decreased to a minimum during S phase. Similarly, cAMP-dependent protein kinase activities peaked at both G(1) and G(2)+M phases of the cell cycle, decreasing to a minimum at S phase. Addition of N6, O-2'-dibutyryl (Bt(2))-cAMP directly stimulated the growth of C. cohnii. Flow cytometric analysis of synchronized C. cohnii cells suggested that 1 mM cAMP shortened the cell cycle, probably at the exit from mitosis, The size of Bt(2)-cAMP treated cells at G(1) was also larger than the control cells. The present study demonstrated a regulatory role of cAMP in the cell cycle progression in dinoflagellates

A dinoflagellate mutant with higher frequency of multiple fission

The dinoflagellate Crypthecodinium cohnii Biecheler propagates by both binary and multiple fission. By a newly developed mutagenesis protocol based on using ethyl methanesulfonate and a cell size screening method, a cell cycle mutant, mf2, was isolated with giant cells which predominantly divide by multiple fission. The average cell size of the mutant mf2 is larger than the control C. cohnii. Cell cycle synchronization experiments suggest that mutant mf2, when compared with the control strain, has a prolonged G(1) phase with a corresponding delay of the G(2)+M phase

Loss of heterozygosity on chromosome 11 in esophageal squamous cell carcinomas

Esophageal cancer (ESC) is an important cancer worldwide. Chromosome 11 plays an important role in the development of several human cancers. In this study, 19 polymorphic microsatellite markers spanning the whole chromosome 11 were used to screen for loss of heterozygosity (LOH) in 38 primary esophageal squamous cell carcinomas. Thirty-three of 38 samples (86.8\%) showed LOH at one or more loci. High frequencies (51.9-61.1\%) of allelic loss were observed at D11S1338, D11S2000, D11S1990, and D11S1647 loci, in two chromosomal regions, 11p15.5 and 11q22.3. The results of this study suggest the presence of putative tumor suppressor genes in these two regions on chromosome 11 related to ESC. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved

A Neuromuscular Junction-like Calcium Release Mechanism In A Unicellular Organism

pp. 111–156 of this Free journal issue entitled: Abstracts of the 24th and the 25th Scientific Meeting of the Hong KongPoster Presentations: no. P-29/25When a myocyte is depolarized by an action potential, calcium ions enter the cell through L-type calcium channels located on the sarcolemma. This calcium, or the physical interaction between the activated L-type calcium channel, triggers a subsequent release of calcium that is stored in the sarcoplasmic reticulum (SR) through calcium-release channels ryanodine receptors. Crypthecodium cohnii is an unicellular dinoflagellate (phyloge-netically related to malarial parasite) with cortical multi-membranous structures apparently similar to the SR. In the present study, both fluorescence-conjugated ryanodine and dihydropyridine gave positive labellings on the cortical area of dinoflagellate cells in where the chlortetracycline-stained calcium stores were located. Either mechanical stimulations or potassium ions could induce membrane potential changes and calcium mobilizations. In addition, cytosolic calcium mobilizations induced by L-type calcium channel agonist (Bay K) was inhibited by ryanodine receptor antagonist (dantrolene). When the membrane potentials were disrupted by sodium ionophore, both mechanically-induced cytosolic calcium mobilizations and membrane potential changes were reduced. This indicated that the dihydropyridine receptor-like protein was upstream of the ryanodine receptor-like channel. Accumulated data, therefore, are consistent with a neuromuscular type excitation-contraction coupling-like mechanism in the dinoflagellates. Acknowledgement: Part of this research was supported by HKUST’s EHIA05/06.SC04 in Molecular Medicine awarded to J.T.Y.W. and S.Y.W.S).link_to_OA_fulltex

Flow cytometric analysis of nocodazole-induced cell-cycle arrest in the pennate diatom Phaeodactylum tricornutum Bohlin

The microtubule inhibitor, nocodazole (2.5 mg L-1), can arrest the cell cycle of the pennate diatom Phaeodactylum tricornutum Bohlin at G(2) + M phase. Flow cytometric analysis of cells treated with nocodazole suggest that the proportion of cells at G(2) + M phase can accumulate to over 95\%. Even after a 48-h treatment with nocodazole (2.5 mg L-1), the cells can still exit mitosis, suggesting that the cell-cycle arrest is reversible

The relationship between affiliate stigma in parents of children with autism spectrum disorder and their children's activity participation

202006 bcrcVersion of RecordOthersPolyU 152110/14EPublishe