Biomimetic synthesis and anti-HIV activity of dimeric phloroglucinols

Plants are an important source of a variety of bioactive compounds with different modes of action. Anti-HIV agents from plant sources can be useful in developing novel therapies for inhibiting HIV infection. Based on the reported anti-HIV activity of plant derived phloroglucinols, several new dimeric phloroglucinols were synthesized in the present study by varying substitution on aromatic ring and at methylene bridge. Some of the synthesized compounds have shown good HIV inhibitory activity in a human CD4+ T cell line (CEM-GFP) infected with HIV-1 NL_4.3 virus isolate. Structure–activity studies indicate that phenyl, 4-benzyloxy-1-phenyl and cyclohexyl substitution at methylene bridge gave compounds with better anti-HIV activity. Compounds 22 and 24 showed highest anti-HIV activity with an IC₅₀ of 0.28 μM and 2.71 μM, respectively, former was more active than the positive standard AZT in cell based assay.     

Analysis of unigene derived microsatellite markers in family solanaceae

The family Solanaceae is the source of several economically important plants. The aim of this study was to trace and characterize simple sequence repeat (SSR) markers from unigene sequences of Solanum lycopersicum, an important member of family Solanaceae. 18,228 unigene sequences of Solanum lycopersicum was taken in order to develop SSR markers and analyzed for the in-silico design of PCR primers. A total of 12,090 (66.32 %) unigenes containing 17,524 SSRs (microsatellites) were identified. The average frequency of microsatellites in unigenes was one in every 1.3 kb of sequence. The analysis revealed that trinucleotide motifs, coding for Glutamic acid (GAA) and AT/TA were the most frequent repeat of dinucleotide SSRs. Flanking sequences of the SSRs generated 877 primers with forward and reverse strands. Functional categorization of SSRs containing unigenes was done through gene ontology terms like Biological process, Cellular component and Molecular function.     

C-reactive Protein Exists in an NaCl Concentration-dependent Pentamer-Decamer Equilibrium in Physiological Buffer

C-reactive protein (CRP) is an acute phase protein of the pentraxin family that binds ligands in a Ca²⁺-dependent manner, and activates complement. Knowledge of its oligomeric state in solution and at surfaces is essential for functional studies. Analytical ultracentrifugation showed that CRP in 2 mm Ca²⁺ exhibits a rapid pentamer-decamer equilibrium. The proportion of decamer decreased with an increase in NaCl concentration. The sedimentation coefficients s_20,w⁰ of pentameric and decameric CRP were 6.4 S and in excess of 7.6 S, respectively. In the absence of Ca²⁺, CRP partially dissociates into its protomers and the NaCl concentration dependence of the pentamer-decamer equilibrium is much reduced. By x-ray scattering, the radius of gyration R_G values ranged from 3.7 nm for the pentamer to above 4.0 nm for the decamer. An averaged K_D value of 21 μm in solution (140 mm NaCl, 2 mm Ca²⁺) was determined by x-ray scattering and modeling based on crystal structures for the pentamer and decamer. Surface plasmon resonance showed that CRP self-associates on a surface with immobilized CRP with a similar K_D value of 23 μm (140 mm NaCl, 2 mm Ca²⁺), whereas CRP aggregates in low salt. It is concluded that CRP is reproducibly observed in a pentamer-decamer equilibrium in physiologically relevant concentrations both in solution and on surfaces. Both 2 mm Ca²⁺ and 140 mm NaCl are essential for the integrity of CRP in functional studies and understanding the role of CRP in the acute phase response.     

A bioremediation approach using natural transformation in pure-culture and mixed-population biofilms

Bacterial transformation by naked DNA is thought to contribute to gene transfer and microbial evolution within natural environments. In nature many microbial communities exist as complex assemblages known as biofilms where genetic exchange is facilitated. It may be possible to take advantage of natural transformation processes to modify the phenotypes of biofilm communities giving them specific and desirable functions. Work described here shows that biofilms composed of either pure cultures or mixed populations can be transformed with specific catabolic genes such that the communities acquire the ability to degrade a particular xenobiotic compound. Biofilms were transformed by plasmids bearing genes encoding green fluorescent protein (mut2) and/or atrazine chlorohydrolase (atzA). Confocal microscopy was used to quantify the number of transformants expressing mut2 in the biofilms. Degradation of atrazine by expressed atzA was quantified by tandem mass spectrometry. PCR analysis was performed to confirm the presence of atzA in transformed biofilms. These results indicate that it should be possible to use natural transformation to enhance bioremediation processes performed by biofilms.     

Mass flux calculations show strong allochthonous support of freshwater zooplankton production is unlikely

Many studies have concluded terrestrial carbon inputs contribute 20-70% of the carbon supporting zooplankton and fish production in lakes. Conversely, it is also known that terrestrial carbon inputs are of very low nutritional quality and phytoplankton are strongly preferentially utilized by zooplankton. Because of its low quality, substantial terrestrial support of zooplankton production in lakes is only conceivable when terrigenous organic matter inputs are much larger than algal production. We conducted a quantitative analysis of terrestrial carbon mass influx and algal primary production estimates for oligo/mesotrophic lakes (i.e., TP ≤ 20 μg L(-1)). In keeping with the principle of mass conservation, only the flux of terrestrial carbon retained within lakes can be utilized by zooplankton. Our field data compilation showed the median (inter-quartile range) terrestrial particulate organic carbon (t-POC), available dissolved organic carbon (t-DOC) inputs, and in-lake bacterial and algal production were 11 (8-17), 34 (11-78), 74 (37-165), and 253 (115-546) mg C m(-2) d(-1), respectively. Despite the widespread view that terrestrial inputs dominate the carbon flux of many lakes, our analysis indicates algal production is a factor 4-7 greater than the available flux of allochthonous basal resources in low productivity lakes. Lakes with high loading of t-DOC also have high hydraulic flushing rates. Because t-DOC is processed, i.e., mineralized or lost to the sediments, in lakes at ≈ 0.1% d(-1), in systems with the highest t-DOC inputs (i.e., 1000 mg m(-2) d(-1)) a median of 98% of the t-DOC flux is advected and therefore is not available to support zooplankton production. Further, advection is the primary fate of t-DOC in lakes with hydraulic retention times <3 years. When taking into account the availability and quality of terrestrial and autochthonous fluxes, this analysis indicates ≈ 95-99% of aquatic herbivore production is supported by in-lake primary production.     

The Dual Arrhenius and Michaelis–Menten kinetics model for decomposition of soil organic matter at hourly to seasonal time scales

Decomposition of soil carbon stocks is one of the largest potential biotic feedbacks to climate change. Models of decomposition of soil organic matter and of soil respiration rely on empirical functions that relate variation in temperature and soil water content to rates of microbial metabolism using soil‐C substrates. Here, we describe a unifying modeling framework to combine the effects of temperature, soil water content, and soluble substrate supply on decomposition of soluble soil‐C substrates using simple functions based on process concepts. The model's backbone is the Michaelis–Menten equation, which describes the relationship between reaction velocity and soluble organic‐C and O₂ substrate concentrations at an enzyme's reactive site, which are determined by diffusivity functions based on soil water content. Temperature sensitivity is simulated by allowing the maximum velocity of the reaction (V_max) to vary according to Arrhenius function. The Dual Arrhenius and Michaelis–Menten kinetics (DAMM) model core was able to predict effectively observations from of laboratory enzyme assays of β‐glucosidase and phenol‐oxidase across a range of substrate concentrations and incubation temperatures. The model also functioned as well or better than purely empirical models for simulating hourly and seasonal soil respiration data from a trenched plot in a deciduous forest at the Harvard Forest, in northeastern United States. The DAMM model demonstrates that enzymatic processes can be intrinsically temperature sensitive, but environmental constrains of substrate supply under soil moisture extremes can prevent that response to temperature from being observed. We discuss how DAMM could serve as a core module that is informed by other modules regarding microbial dynamics and supply of soluble‐C substrates from plant inputs and from desorption of physically stabilized soil‐C pools. Most importantly, it presents a way forward from purely empirical representation of temperature and moisture responses and integrates temperature‐sensitive enzymatic processes with constraints of substrate supply.     

Improved Glycaemia Correlates with Liver Fat Reduction in Obese,Type 2 Diabetes,Patients Given Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists

Glucagon-like peptide-1 receptor agonists (GLP-1 RA) are effective for obese patients with type 2 diabetes mellitus (T2DM) because they concomitantly target obesity and dysglycaemia. Considering the high prevalence of non-alcoholic fatty liver disease (NAFLD) in patients with T2DM, we determined the impact of 6 months’ GLP-1 RA therapy on intrahepatic lipid (IHL) in obese, T2DM patients with hepatic steatosis, and evaluated the inter-relationship between changes in IHL with those in glycosylated haemoglobin (HbA₁c), body weight, and volume of abdominal visceral and subcutaneous adipose tissue (VAT and SAT). We prospectively studied 25 (12 male) patients, age 50±10 years, BMI 38.4±5.6 kg/m² (mean ± SD) with baseline IHL of 28.2% (16.5 to 43.1%) and HbA₁c of 9.6% (7.9 to 10.7%) (median and interquartile range). Patients treated with metformin and sulphonylureas/DPP-IV inhibitors were given 6 months GLP-1 RA (exenatide, n = 19; liraglutide, n = 6). IHL was quantified by liver proton magnetic resonance spectroscopy (¹H MRS) and VAT and SAT by whole body magnetic resonance imaging (MRI). Treatment was associated with mean weight loss of 5.0 kg (95% CI 3.5,6.5 kg), mean HbA_1c reduction of 1·6% (17 mmol/mol) (0·8,2·4%) and a 42% relative reduction in IHL (−59.3, −16.5%). The relative reduction in IHL correlated with that in HbA₁c (ρ = 0.49; p = 0.01) but was not significantly correlated with that in total body weight, VAT or SAT. The greatest IHL reduction occurred in individuals with highest pre-treatment levels. Mechanistic studies are needed to determine potential direct effects of GLP-1 RA on human liver lipid metabolism.     

A novel role for villin in intestinal epithelial cell survival and homeostasis

Apoptosis is a key regulator for the normal turnover of the intestinal mucosa, and abnormalities associated with this function have been linked to inflammatory bowel disease and colorectal cancer. Despite this, little is known about the mechanism(s) mediating intestinal epithelial cell apoptosis. Villin is an actin regulatory protein that is expressed in every cell of the intestinal epithelium as well as in exocrine glands associated with the gastrointestinal tract. In this study we demonstrate for the first time that villin is an epithelial cell-specific anti-apoptotic protein. Absence of villin predisposes mice to dextran sodium sulfate-induced colitis by promoting apoptosis. To better understand the cellular and molecular mechanisms of the anti-apoptotic function of villin, we overexpressed villin in the Madin-Darby canine kidney Tet-Off epithelial cell line to demonstrate that expression of villin protects cells from apoptosis by maintaining mitochondrial integrity thus inhibiting the activation of caspase-9 and caspase-3. Furthermore, we report that the anti-apoptotic response of villin depends on activation of the pro-survival proteins, phosphatidylinositol 3-kinase and phosphorylated Akt. The results of our studies shed new light on the previously unrecognized function of villin in the regulation of apoptosis in the gastrointestinal epithelium.     

Atypical antipsychotic drugs and risk of ischaemic stroke: population based retrospective cohort study

Objective To compare the incidence of admissions to hospital for stroke among older adults with dementia receiving atypical or typical antipsychotics.Design Population based retrospective cohort study.Setting Ontario, Canada.Patients 32 710 older adults (≤ 65 years) with dementia (17 845 dispensed an atypical antipsychotic and 14 865 dispensed a typical antipsychotic).Main outcome measures Admission to hospital with the most responsible diagnosis (single most important condition responsible for the patient''s admission) of ischaemic stroke. Observation of patients until they were either admitted to hospital with ischaemic stroke, stopped taking antipsychotics, died, or the study ended.Results After adjustment for potential confounders, participants receiving atypical antipsychotics showed no significant increase in risk of ischaemic stroke compared with those receiving typical antipsychotics (adjusted hazard ratio 1.01, 95% confidence interval 0.81 to 1.26). This finding was consistent in a series of subgroup analyses, including ones of individual atypical antipsychotic drugs (risperidone, olanzapine, and quetiapine) and selected subpopulations of the main cohorts.Conclusion Older adults with dementia who take atypical antipsychotics have a similar risk of ischaemic stroke to those taking typical antipsychotics.     

Subject index volume 144

Abstract β-xylosidase (EC 3.2.1.37) has been purified from Aspergillus nidulans mycelium grown on oat-spelt xylan as sole carbon source. Its pH optimum for activity was found to be 5.0 and the optimum temperature was 50 °C. Its molecular mass was estimated by gel filtration to be 180000. Using p-nitrophenyl-β-d-xylopyranoside as substrate, the K _m and V _max values have been found to be 1.1 mM and 25.6 μmol min⁻¹(mg protein)⁻¹, respectively. Enzyme activity was inhibited by Hg²⁺, Ag²⁺, and Cu²⁺ at a concentration of 1 × 10⁻³ M. The synthesis of β-xylosidase in A. nidulans is strongly induced by arabinose and xylose and is subject to carbon catabolite repression mediated by the cre A gene product.