Synthesis of High Density Insensitive Energetic Tetraazapentalene Derivatives

An improved nitration procedure has been developed for the synthesis of y-Tacot (3). The synthesis of y-DBBD (8) has been completed in three steps from 3 in 37% yield. y-DBBD (8) was found to be thermally stable up to 274 °C (decomposed) and insensitive to impact (hammer blow). Nitration of z-BDDB (6) and y-DBBD (8) gave carbonyl derivatives resulting from in situ hydroysis/oxidation of the corresponding tetranitro derivatives z-TBBD (7) and y-TBBD (9), respectively.

Electrolytic recovery of dilute copper from a mixed industrial effluent of high strength COD

In this study, the electrochemical treatment has been investigated in the real acidic effluent of copper-phthalocyanine dye manufacturing plant. Galvanostatic batch electrolyses have been carried out in an undivided cell using stainless steel as cathode, dimensionally stable anode (DSA) and graphite as anodes at different current densities and temperatures. The influence of these variables on current efficiency, cell voltage, energy consumption and deposit quality was reported. Under optimized conditions, the maximum copper recovery of 98% and COD removal efficiency of 87.3% with the energy consumption of about 11.23 kWh/kg of Cu and 6.08 kWh/kg of COD, respectively at 30 degrees C were achieved in the acidic raw effluent using 2D parallel-plate cathode. While in 3D stainless steel turning cathode reactor, 99.5% of copper can efficiently be recovered from dilute solution with an acceptable current efficiency of about 56.8% with minimum energy consumption of 2.37 kWh/kg of Cu. The experimental results suggested that the efficiency of copper removal is hindered by the presence of organic species in the mixed industrial effluent.

Risk factors for posterior compared to anterior ischemic stroke: an observational study of the Registry of the Canadian Stroke Network

BACKGROUND

Traditional vascular risk factors appear to exert varying magnitudes of risk for different major vascular events. For example, hypercholesterolemia is a much stronger risk factor for myocardial infarction than ischemic stroke. Limited evidence also suggests that vascular risk factors may exert differing magnitudes of risk for ischemic stroke within different cerebral arterial territories. We sought to determine the association between traditional vascular risk factors and the location of ischemic stroke (posterior versus anterior).

METHODS

Consecutive patients with acute ischemic stroke who were admitted to 11 regional stroke centers within the Registry of the Canadian Stroke Network were included in the study sample. The Oxfordshire Community Stroke Project classification was used to distinguish posterior from anterior circulation ischemic stroke. Multivariable logistic regression was applied to determine the association between risk factors (age, gender, diabetes mellitus, hypercholesterolemia, hypertension, atrial fibrillation and smoking history) and posterior (compared to anterior) circulation ischemic stroke.

RESULTS

In total, 8,489 patients with acute ischemic stroke were included. On multivariable analysis, diabetes mellitus (OR = 1.14; 95% CI = 1.02-1.27) was associated with an increased odds of posterior circulation ischemic stroke, whereas age (OR = 0.86; 95% CI = 0.83-0.90), female sex (OR = 0.84; 95% CI = 0.76-0.93), atrial fibrillation (OR = 0.83; 95% CI = 0.74-0.94) and pulmonary edema (OR = 0.74; 95% CI = 0.62-0.88) were related to a reduced odds of posterior compared with anterior circulation ischemic stroke.

CONCLUSIONS

Some traditional vascular risk factors for ischemic stroke appear to exert different magnitudes of risk for posterior compared to anterior circulation ischemic stroke.

Cathodic behaviour of stainless steel in coastal Indian seawater: calcareous deposits overwhelm biofilms

Type-316 stainless steel (SS) was investigated as the cathode in galvanic couples in full-strength seawater from the Gulf of Mannar on the southeast coast of India. Tests were devised to examine the impact of SS cathodes on anode materials with or without the accrual of marine biofilms. Biofilmed SS cathodes significantly enhanced the rate of corrosion of nickel, causing noble shifts in the couple potentials. With mild steel and zinc as the anodes, calcareous deposits developed quite rapidly on the SS cathodes and led to a significant reduction of bacterial numbers. The calcareous deposits also caused substantial reduction of galvanic corrosion rates for mild steel, whereas there was no difference for zinc. The deposits were identified by XRD as essentially carbonates, oxides and hydroxides of calcium and magnesium. Potentiodynamic polarization performed on the actual couples after disconnection and equilibration provided reasonable interpretations of the galvanic corrosion trends. Data from this work suggest that a potential of about -0.70 V vs. saturated calomel electrode (SCE) should provide optimum protection of SS in warmer, full-strength seawater that supports the precipitation of calcareous deposits. The criterion commonly recommended for temperate conditions of lower water temperature and estuarine waters of lower alkalinity is -1.0 V (SCE).

Free radical scavenging and radioprotective activity of dehydrozingerone against whole body gamma irradiation in Swiss albino mice

Dehydrozingerone (DZ) was explored for in vitro-in vivo antioxidant potential and in vivo radioprotective activity against whole body gamma irradiation in Swiss albino mice. DZ scavenged the ABTS (2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (1, 1-dipehnyl-2-picrylhydrazyl) free radicals at room temp. DZ reduced Fe (III) to Fe (II) at pH 7.4 and scavenged the NADH/phenazine methosulfate generated superoxide radical in cell free system. DZ also scavenged the nitric oxide radical generated by sodium nitroprusside. To evaluate the radioprotective activity, mice were exposed to whole body gamma irradiation 30 min after the drug treatment at a dose rate of 1.66 Gy/min. Pretreatment with DZ 75, 100 and 125 mg/kg, i.p. reduced the radiation induced mortality and increased the mean survival times (MSTs). An i.p. dose of DZ 100 mg/kg was found the most effective dose in preventing radiation sickness and increasing the MST. Pretreatment DZ100 mg/kg maintained the spleen index (spleen weight/body weight x 100) and stimulates the endogenous spleen colony forming units (CFU). Pretreatment with DZ100 mg/kg maintained the villus height close to normal, prevents mucosal erosion and basement membrane damage in irradiated mice jejunum. However, no significant reductions in dead, inflammatory and mitotic cells were observed in DZ pretreated mice, but there was an increased in crypt cells proliferation and regeneration. Pretreatment with DZ100 mg/kg significantly elevated the endogenous antioxidant enzymes (GSH, GST and SOD) in mice at 2, 4 and 8 h post sham irradiation. Radiation induced fall in endogenous antioxidant enzymes was significantly prevented by DZ pretreatment. Pretreatment with DZ 75 and 100 mg/kg reduced the radiation induced micronucleated polychromatic erythrocytes (MPCE) and normochromatic erythrocytes (MNCE) in mice bone marrow. DZ also maintained the polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) ratio (P/N ratio) in irradiated mice. Dose modifying factor (DMF) was calculated by using the graded radiation dose (8.0, 9.0, 9.5 and 10 Gy). DZ 100 mg/kg elevated radiation LD(50) from 9.1 to 10.0 Gy, indicating the DMF of 1.09.

Development and validation of a reversed-phase liquid chromatographic method with fluorescence detection for the study of Saquinavir pharmacokinetics in rat plasma

This research work aims to exploit the high selectivity and sensitivity of fluorescence detector to develop and validate a high performance liquid chromatography (HPLC) method having very small sampling volume, much better mass-sensitive detection limit and lower operating cost for the determination of Saquinavir (SQV), known to have low oral bioavailability, in rat plasma. Unlike the traditional methods that require at least 0.25 mL of plasma for each measurement, the present method requires only a 0.1 mL sample volume. This is very useful in reducing the blood collection from study rats, offering the possibility to make sufficient number of samples for pharmacokinetic study and minimizing the amount of blood-derived biological waste. After liquid-liquid extraction, the compounds were separated on a Vydac C18 monomeric column (250 mm x 4.6 mm i.d. x 5 microm particle size) using a mobile phase composed of acetonitrile and potassium dihydrogen phosphate buffer (45:55, v/v). Fluorescence detection was performed at 237 nm (excitation) and 380 nm (emission). Validity of the method was studied and the method was found to be precise and accurate with a linearity range from 0.005 to 1.000 microg mL(-1) (r>0.9980). The limit of detection (LOD) was found to be 0.001 microg mL(-1). The intra-day and inter-day precision studies showed good reproducibility with coefficients of variation (C.V.) less than 11.4%. The developed method was applied successfully to monitor the pharmacokinetic profile following oral administration of SQV to rats.

Stability-indicating HPTLC determination of imatinib mesylate in bulk drug and pharmaceutical dosage form

A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of imatinib mesylate both as a bulk drug and in formulations was developed and validated. The method employed HPTLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of chloroform:methanol (6:4, v/v). The system was found to give compact spot for imatinib mesylate (R(f) value of 0.53+/-0.02). Densitometric analysis of imatinib mesylate was carried out in the absorbance mode at 276 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r(2)=0.9966+/-0.0013 with respect to peak area in the concentration range 100-1000 ng per spot. The mean value+/-S.D. of slope and intercept were 164.85+/-0.72 and 1168.3+/-8.26 with respect to peak area. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 10 and 30 ng per spot, respectively. Imatinib mesylate was subjected to acid and alkali hydrolysis, oxidation and thermal degradation. The drug undergoes degradation under acidic, basic, oxidation and heat conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation and heat. Statistical analysis proves that the method is repeatable, selective and accurate for the estimation of said drug. The proposed developed HPTLC method can be applied for identification and quantitative determination of imatinib mesylate in bulk drug and dosage forms.

Modeling of phosphomethyl pyrimidine kinase from Leptospira interrogans serovar lai strain 56601

Many microorganisms, as well as plants and fungi, synthesize thiamin, but vertebrates do not produce it. Phosphomethyl pyrimidine kinase is an enzyme involved in an intermediary step of thiamin biosynthesis from purine molecules. This enzyme is absent in humans. Thus, it is a potential chemotherapeutic target for antileptospiral treatment. Structure of this enzyme from Leptospira interrogans serovar lai strain 56601 has not yet been elucidated. We used the structural template of phosphomethyl pyrimidine kinase from Thermus thermophilus HB8 for modeling the phosphomethyl pyrimidine kinase structure from Leptospira interrogans serovar lai strain 56601 . The model is deposited in Protein Data Bank (PDB ID: 2G53) at RCSB. Thus, we analyse and propose the usefulness of the modeled phosphomethyl pyrimidine kinase for the design of suitable inhibitors towards the treatment of leptospirosis.

Centrifugal forces alter streamline topology and greatly enhance the rate of heat and mass transfer from neutrally buoyant particles to a shear flow

Centrifugal forces break the degenerate closed-streamline configuration that occurs in simple shear flow past a neutrally buoyant torque-free particle in the inertialess limit. The broken symmetry allows heat or mass to be convected away in an efficient manner in sharp contrast to the inertialess diffusion-limited scenario. The dimensionless transfer rate, characterized by the Nusselt number, is found to be Nu = 0.33(RePe)(1/3) + O(1) for small but finite Re when RePe >> 1. Here, the particle Reynolds number (Re) is a dimensionless measure of the inertial forces, while the Peclet number (Pe) measures the relative importance of the convective and the diffusive transfer mechanisms. The symmetry-breaking bifurcation is expected to occur in generic shearing flows, and represents a possible means for heat or mass transfer enhancement from the dispersed phase in multiphase systems.

Plasmodium falciparum: Characterization of a late asexual stage Golgi protein containing both ankyrin and DHHC domains

Proteins containing the DHHC motif have been shown to function as palmitoyl transferases. The palmitoylation of proteins has been shown to play an important role in the trafficking of proteins to the proper subcellular location. Herein, we describe a protein containing both ankyrin domains and a DHHC domain that is present in the Golgi of late schizonts of P. falciparum. The timing of expression as well as the location of this protein suggests that it may play an important role in the sorting of proteins to the apical organelles during the development of the asexual stage of the parasite.

Multiple transporters associated with malaria parasite responses to chloroquine and quinine

Mutations and/or overexpression of various transporters are known to confer drug resistance in a variety of organisms. In the malaria parasite Plasmodium falciparum, a homologue of P-glycoprotein, PfMDR1, has been implicated in responses to chloroquine (CQ), quinine (QN) and other drugs, and a putative transporter, PfCRT, was recently demonstrated to be the key molecule in CQ resistance. However, other unknown molecules are probably involved, as different parasite clones carrying the same pfcrt and pfmdr1 alleles show a wide range of quantitative responses to CQ and QN. Such molecules may contribute to increasing incidences of QN treatment failure, the molecular basis of which is not understood. To identify additional genes involved in parasite CQ and QN responses, we assayed the in vitro susceptibilities of 97 culture-adapted cloned isolates to CQ and QN and searched for single nucleotide polymorphisms (SNPs) in DNA encoding 49 putative transporters (total 113 kb) and in 39 housekeeping genes that acted as negative controls. SNPs in 11 of the putative transporter genes, including pfcrt and pfmdr1, showed significant associations with decreased sensitivity to CQ and/or QN in P. falciparum. Significant linkage disequilibria within and between these genes were also detected, suggesting interactions among the transporter genes. This study provides specific leads for better understanding of complex drug resistances in malaria parasites.