Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna.

Background: To better understand the potential ecotoxicological impacts of silver nanoparticles released into freshwater environments, the Daphnia magna 48-hour immobilization test was used.

Methods: The toxicities of silver nitrate, two types of colloidal silver nanoparticles, and a suspension of silver nanoparticles were assessed and compared using standard OECD guidelines. Also, the swimming behavior and visible uptake of the nanoparticles by Daphnia were investigated and compared.

Temperature, organic solvent and pH stabilization of the neutral protease from Salinovibrio proteolyticus: significance of the structural calcium.

In order to clarify the impact of Ca-binding sites (Ca1 and 2) on the conformational stability of neutral proteases (NPs), we have analyzed the thermal, pH and organic solvent stability of a NP variant, V189P/A195E/G203D/A268E (Q-mutant), from Salinovibrio proteolyticus. This mutant has shown to bind calcium more tightly than the wild-type (WT) at Ca1 and to possess Ca2. Q-mutant was resisted against autolysis, thermoinactivation and pH denaturation in a Ca-dependent manner and exhibited better activity in organic solvents compared to the WT enzyme.

An analysis of temperature adaptation in cold active, mesophilic and thermophilic Bacillus α-amylases.

A comparative biochemical and structural study was performed on a cold active α-amylase from Bacillus cereus (BCA) and two well-known homologous mesophilic and thermophilic α-amylases from Bacillus amyloliquefaciens (BAA) and Bacillus licheniformis (BLA). In spite of a high degree of sequence and structural similarity, drastic variations were found for T(opt) as 50, 70 and 90°C for BCA, BAA and BLA, respectively. The half-lives of thermoinactivation were 1 and 9 min for BCA and BAA at 80°C respectively, whilst there was no inactivation for BLA at this temperature.

Secular trends of hip fractures in Québec, Canada.

Unlabelled: This study examined the secular trends of hip fracture incidence among individuals 50 years and older in Québec between 1993 and 2004. Age-standardized rates decreased at both the provincial and regional levels. The largest relative decrease was observed among younger females, and rates declined more slowly in the elderly.

Pattern of mid-facial fractures in Tehran, Iran.

Background/aim: One of the highest rates of car accidents and related morbidities and mortalities in the world is reported from Iran. Facial structures are usually injured in such accidents. This study is conducted to find the patterns and etiologies of mid-facial fractures in Iran.

A Facile One-Pot Synthesis of Functionalized 4,8-Dihydropyrano[3,2-b]-pyran-4-ones.

The reactive intermediates generated by the addition of alkyl isocyanides and dialkyl acetylenedicarboxylates were trapped by 5-hydroxy-2-hydroxymethyl-4H-pyran-4-one (kojic acid) to yield functionalized 4,8-dihydropyrano[3,2-b]-pyran-4-ones at ambient temperature in good yields.

Evidence-based approach to HIV/AIDS policy and research prioritization in the Islamic Republic of Iran.

In formulating the second national strategic plan for prevention of HIV/AIDS in the Islamic Republic of Iran a more evidence-based approach was needed. This paper reports on a systematic review of the local evidence about the determinants of HIV/AIDS transmission in 3 categories: poor knowledge and negative attitudes about HIV transmission; injection drug use; and sexual promiscuity. Of 93 reports reviewed, 53 met the inclusion criteria.

Enhanced activity and stability in the presence of organic solvents by increased active site polarity and stabilization of a surface loop in a metalloprotease.

Salinivibrio zinc-metalloprotease (SVP) is an enzyme which was isolated from Salinivibrio proteolyticus, a moderately halophilic species from a hypersaline lake in Iran. A195E and G203D mutants were constructed to increase polarity near the active site in order to preserve the hydration layer against organic solvents [dimethylformamide (DMF), methanol, isopropanol and n-propanol]. A268P was constructed to stabilize a surface loop far from the active site and A195E/A268P was constructed to investigate the combined effects of these two mutations.

Remarkable improvements of a neutral protease activity and stability share the same structural origins.

Stabilizing an enzyme while improving its activity may be difficult with respect to a general trade off relation between stability and function at the level of individual mutations. We have used site-directed mutagenesis to investigate the possibility of parallel improvements of thermostability and activity in the neutral protease from Salinovibrio proteolyticus. Four out of seven point mutations are able to promote both activity and thermostability individually and combinedly.

Cloning, expression, and characterization of a novel methylglyoxal synthase from Thermus sp. strain GH5.

A gene encoding methylglyoxal synthase from Thermus sp. GH5 (TMGS) was cloned, sequenced, overexpressed, and purified by Q-Sepharose. The TMGS gene was composed of 399 bp which encoded a polypeptide of 132 amino acids with a molecular mass of 14.

Adherence to vascular protection drugs in diabetic patients in Quebec: a population-based analysis.

The purpose of this study was to assess adherence to vascular protection drugs in diabetic patients using a cohort of diabetic patients aged >or=30 years, covered by the public drug insurance in the province of Quebec, excluding gestational diabetes and patients who were hopitalized or died during the 1-year follow-up. Drug adherence was measured using the medication possession ratio. Multivariate analyses, including logit and multinomial logit were used.

Stroke and cardiovascular morbidity and mortality associated with rosiglitazone use in elderly diabetic patients.

The objective was to evaluate the cardiovascular risks associated with rosiglitazone in diabetic patients. We conducted matched nested case-control studies in a retrospective population-based cohort of all elderly diabetic patients living in Quebec throughout 2001 and 2002. Study end-points were: all-cause and cardiovascular death, hospital admission for AMI, CHF and stroke.

Disparities between rural and urban areas for osteoporosis management in the province of Quebec following the Canadian 2002 guidelines publication.

Rationale, Aims And Objectives: Clinical guidelines have been seen as a tool for improving management of osteoporosis in order to prevent fragility fractures. However, the impact of guidelines on clinical management of osteoporosis has not been measured. We examined medical investigation and treatment before and after the 2002 Canadian guidelines publication and examined if practice changes were different between rural and urban areas.

Optimal strategy to identify incidence of diagnostic of diabetes using administrative data.

Background: Accurate estimates of incidence and prevalence of the disease is a vital step toward appropriate interventions for chronic disease like diabetes. A growing body of scientific literature is now available on producing accurate information from administrative data. Advantages of use of administrative data to determine disease incidence include feasibility, accessibility and low cost, but straightforward use of administrative data can produce biased information on incident cases of chronic disease like diabetes.

One-pot synthesis of 4-arylquinolines from aromatic aminoketones and vinylphosphonium salts.

The addition of acetylenic esters to aromatic amines such as 2-amino benzophenone derivatives in the presence of triphenylphosphine leads to highly functionalized phosphoranes, which undergo an intramolecular Wittig reaction following oxidation to produce quinoline derivatives.

Early morning surge and dipping status of blood pressure: are these of predictive value for silent myocardial ischemia?

To investigate the predictive value of morning surge (MS) and dipping status of blood pressure (BP) for ST-segment depression (ST depression) in hypertensive persons, the combined 24-hour ambulatory BP measurement and Holter electrocardiographic recordings of 344 patients (132 women and 212 men, 60+/-12 years) were analyzed. The morning BP surge was calculated as mean systolic BP during the 2 hours after awaking minus the mean systolic BP during the 1 hour that included the lowest sleep BP. Depending on the percentage decrease in systolic BP at night, patients were subdivided into extreme dippers, dippers, nondippers, and risers.

Isolation and characterization of a novel gamma-radiation-resistant bacterium from hot spring in Iran.

30 pure colonies with various colors and shapes were isolated from the samples of water and mud which were collected from the Abe-Siah hot springs in Ramsar, a city in north of Iran, with high-level of radiation (up to 4 Gy). Colonies were irradiated by 22 KGy radiations and only one of them survived. The survived bacterium with an optimum growth of 30 to 37 degrees C, pH 6 to 7, and at minimum of 5% NaCl concentration showed promising characteristics.

A facile route to diastereomeric phosphorus ylides. Chemoselective synthesis of dialkyl (E)-2-[1-(2-oxocyclopentylidene)ethyl]-2-butenedioates.

2-Acetylcyclopentanone undergoes a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates to produce dialkyl 2-(1-acetyl-2-oxocyclopentyl)-3-(1,1,1-triphenyl-lambda(5)-phosphanylidene)succinates. These compounds undergo intramolecular Wittig reactions in boiling benzene to produce highly strained spirocyclobutene derivatives, which spontaneously undergo ring-opening reactions to produce dialkyl (E)-2-[1-(2-oxocyclopentyliden)ethyl]-2-butenedioates.

Long term regional migration patterns of physicians over the course of their active practice careers.

Introduction: The geographic distribution of physicians in the United States of America has been often described as unbalanced or maldistributed. There is much in the literature on the regional distribution of physicians but far less is written about their pattern of movement. This study aimed to examine the geographic transition of physicians at two points in time (1981 and 2003), in and out the four US census regions (Northeast, Midwest, South, and West).

Optical characterization of porous silicon and crystalline silicon by the Kramers-Kronig method.

The electronic structure of porous silicon (PS) has been characterized by optical reflectance spectra analyses. Using a Cary-500 spectrometer, the reflectance spectra of PS are measured in the photon energy range of 0.4-6 eV.

Comparative studies on trifluoroethanol (TFE) state of a thermophilic alpha-amylase and its mesophilic counterpart: limited proteolysis, conformational analysis, aggregation and reactivation of the enzymes.

Detailed circular dichroism (CD), scattering and quenching studies, 1-anilinonaphthalene-8-sulfonate (ANS) binding, irreversible thermoinactivation, activity measurements and proteolytic digestion of bacterial alpha-amylases have been carried out to elucidate the effect of trifluoroethanol (TFE) on the structure of these enzymes. Under high concentrations of TFE both of the alpha-amylases, a thermostable alpha-amylase from Bacillus licheniformis (BLA) and its mesophilic counterpart from Bacillus amyloliquefaciens (BAA), acquire partially folded state characterized by an enhanced content of the secondary structure (helix) and reduced tertiary structures. According to ANS binding studies, we suggest that the TFE states induced by TFE/water mixture are not the molten globule state in the alpha-amylase folding pathway.