Contribution of infection and vaccination to population-level seroprevalence through two COVID waves in Tamil Nadu, India

This study employs repeated, large panels of serological surveys to document rapid and substantial waning of SARS-CoV-2 antibodies at the population level and to calculate the extent to which infection and vaccination separately contribute to seroprevalence estimates. Four rounds of serological surveys were conducted, spanning two COVID waves (October 2020 and April-May 2021), in Tamil Nadu (population 72 million) state in India. Each round included representative populations in each district of the state, totaling ≥ 20,000 persons per round. State-level seroprevalence was 31.5% in round 1 (October-November 2020), after India's first COVID wave. Seroprevalence fell to 22.9% in round 2 (April 2021), a roughly one-third decline in 6 months, consistent with dramatic waning of SARS-Cov-2 antibodies from natural infection. Seroprevalence rose to 67.1% by round 3 (June-July 2021), with infections from the Delta-variant induced second COVID wave accounting for 74% of the increase. Seroprevalence rose to 93.1% by round 4 (December 2021-January 2022), with vaccinations accounting for 63% of the increase. Antibodies also appear to wane after vaccination. Seroprevalence in urban areas was higher than in rural areas, but the gap shrunk over time (35.7 v. 25.7% in round 1, 89.8% v. 91.4% in round 4) as the epidemic spread even in low-density rural areas.

Impact of DHCWs' Safety Perception on Vaccine Acceptance and Adoption of Risk Mitigation Strategies

OBJECTIVES

To estimate the association between safety perception on vaccine acceptance and adoptions of risk mitigation strategies among dental health care workers (DHCWs).

METHODS

A survey was emailed to DHCWs in the New Jersey area from December 2020 to January 2021. Perceived safety from regular SARS-CoV-2 testing of self, coworkers, and patients and its association with vaccine hesitancy and risk mitigation were ascertained. Risk Mitigation Strategy (RiMS) scores were computed from groupings of office measures: 1) physical distancing (reduced occupancy, traffic flow, donning of masks, minimal room crowding), 2) personal protective equipment (fitted for N95; donning N95 masks; use of face shields; coverings for head, body, and feet), and 3) environmental disinfection (suction, air filtration, ultraviolet, surface wiping).

RESULTS

SARS-CoV-2 testing of dental professionals, coworkers, and patients were perceived to provide safety at 49%, 55%, and 68%, respectively. While dentists were least likely to feel safe with regular self-testing for SARS-CoV-2 (P < 0.001) as compared with hygienists and assistants, they were more willing than hygienists (P = 0.004; odds ratio, 1.79 [95% CI, 1.21 to 2.66]) and assistants (P < 0.001; odds ratio, 3.32 [95% CI, 1.93 to 5.71]) to receive the vaccine. RiMS scores ranged from 0 to 19 for 467 participants (mean [SD], 10.9 [2.9]). RiMS scores did not significantly differ among groups of DHCWs; however, mean RiMS scores were higher among those who received or planned to receive the COVID-19 vaccine than those with who did not (P = 0.004). DHCWs who felt safer with regular testing had greater RiMS scores than those who did not (11.0 vs. 10.3, P = 0.01).

CONCLUSIONS

Understanding DHCWs' perception of risk and safety is crucial, as it likely influences attitudes toward testing and implementation of office risk mitigation policies. Clinical studies that correlate risk perception and RiMS with SARS-CoV-2 testing are needed to demonstrate the effectiveness of RiMS in dental care settings.

KNOWLEDGE TRANSFER STATEMENT

Educators, clinicians, and policy makers can use the results of this study when improving attitudes toward testing and implementation of risk mitigation policies within dental offices, for current and future pandemics.

Antibacterial Activity of Ulva lactuca against Multidrug Resistant and Betalactamase Producing Isolates from Food Samples- An In-vitro Study

Introduction: Antibiotic resistance is a problem of deep scientific concern, both in hospital and community settings. Due the presence of highly resistant microorganisms in food, it may lead to serious health issues to the human beings and other animals also. This can be controlled by novel control methods using natural products. Algae are one such wonderful source that helps in treating such dreadful microorganisms. Ulva lactuca incorporate discrete active compounds, hence, exhibit antibacterial property to control the multidrug resistant bacteria. The present research aims in exploring the potential antibacterial property of such dreadful bacteria. Aim: To evaluate the potential bioactive compound of Ulva lactuca and its antibacterial activity against Multidrug Resistant (MDR) and betalactamase producing food isolates. Materials and Methods: The present pilot in-vitro study was carried out at Arignar Anna Government Arts College, Namakkal, Tamil Nadu, India, in the period of December 2017 to December 2020. Total 18 bacterial isolates were isolated from five retail chicken meat samples. These were then, tested for its antibiotic resistance property using standard antibiotic discs. The algae Ulva lactuca was isolated and extract was prepared using ethanol and chloroform solvents, followed by which the phytochemical studies were performed. These extracts were then tested, against the selected organisms for its potential activity. Results: Among the 12 antibiotics tested, all isolates were resistance to variety of antibiotic classes, mainly aminoglycosides, cephalosporins, and fluoroquinolones and also 55% of the bacteria were able to produce betalactamase enzyme. The ethanol extract of Ulva lactuca was highly active against all isolates and exhibited a range of 10±1.24 mm to 22±1.24 mm inhibition zone. The chloroform extract, exhibited less potency, which exhibited 10±0.816 mm to 13.16±1.027 mm inhibition zone. Each organic solvent showed positive result for following metabolites- alkaloids, carbohydrates, flavonoids, sterols, tannins and terpenoids. Conclusion: The ethanolic extract of Ulva lactuca was very effective against the selected MDR and betalactamase producing food isolates. Therefore, it could be suggested as an antibacterial agent in the future. Further studies are needed to reveal the behavioural mechanisms of this plant and its pharmacological effects.

Factors Associated With the Decay of Anti-SARS-CoV-2 S1 IgG Antibodies Among Recipients of an Adenoviral Vector-Based AZD1222 and a Whole-Virion Inactivated BBV152 Vaccine

Background

The magnitude of protection conferred following recovery from COVID-19 or by vaccine administration, and the duration of protective immunity developed, remains ambiguous.

Methods

We investigated the factors associated with anti-SARS-CoV-2 S1 IgG decay in 519 individuals who recovered from COVID-19 illness or received COVID-19 vaccination with two commercial vaccines, viz., an adenoviral vector-based (AZD1222) and a whole-virion-based inactivated (BBV152) vaccine in Chennai, India from March to December 2021. Blood samples collected during regular follow-up post-infection/-vaccination were examined for anti-SARS-CoV-2 S1 IgG by a commercial automated chemiluminescent immunoassay (CLIA).

Results

Age and underlying comorbidities were the two variables that were independently associated with the development of a breakthrough infection. Individuals who were >60 years of age with underlying comorbid conditions (viz., hypertension, diabetes mellitus and cardiovascular disease) had a ~15 times and ~10 times greater odds for developing a breakthrough infection and hospitalization, respectively. The time elapsed since the first booster dose was associated with attrition in anti-SARS-CoV-2 IgG, where each month passed was associated with an ebb in the anti-SARS-CoV-2 IgG antibody levels by a coefficient of -6 units.

Conclusions

Our findings advocate that the elderly with underlying comorbidities be administered with appropriate number of booster doses with AZD1222 and BBV152 against COVID-19.

Regional Mechanical Thrombectomy Imaging Protocol in Patients Presenting with Acute Ischemic Stroke during the COVID-19 Pandemic

BACKGROUND AND PURPOSE

Chest CT is a rapid, useful additional screening tool for coronavirus disease 2019 (COVID-19) in emergent procedures. We describe the feasibility and interim outcome of implementing a modified imaging algorithm for COVID-19 risk stratification across a regional network of primary stroke centers in the work-up of acute ischemic stroke referrals for time-critical mechanical thrombectomy.

MATERIALS AND METHODS

We undertook a retrospective review of 49 patients referred to the regional neuroscience unit for consideration of mechanical thrombectomy between April 14, 2020, and May 21, 2020. During this time, all referring units followed a standard imaging protocol that included a chest CT in addition to a head CT and CT angiogram to identify Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infective pulmonary changes.

RESULTS

Overall, 2 patients had typical COVID-19 radiologic features and tested positive, while 7 patients had indeterminate imaging findings and tested negative. The others had normal or atypical changes and were not diagnosed with or suspected of having COVID-19. There was an overall sensitivity of 100%, specificity of 74.1%, negative predictive value of 100%, and positive predictive value of 22.2% when using chest CT to diagnose COVID-19 in comparison with the real-time reverse transcriptase-polymerase chain reaction test. The mean additional time and radiation dose incurred for the chest CT were 184 ± 65.5 seconds and 2.47 ± 1.03 mSv. Multiple cardiovascular and pulmonary incidental findings of clinical relevance were identified in our patient population.

CONCLUSIONS

Chest CT provides a pragmatic, rapid additional tool for COVID-19 risk stratification among patients referred for mechanical thrombectomy. Its inclusion in a standardized regional stroke imaging protocol has enabled efficient use of hospital resources with minimal compromise or delay to the overall patient treatment schedule.

Isolation of rickettsia helvetica from ticks in Slovakia

To date, only three rickettsial species have been found in ticks in Slovakia by serological and/or molecular-biological techniques, namely Rickettsia slovaca, Candidatus rickettsia IRS, and Rickettsia raoultii. Recently, we succeeded in isolation of the forth species, Rickettsia helvetica from Ixodes ricinus, the most frequent tick in Slovakia. The isolation, positive for 10% of tested ticks, was performed on XTC cells by the shell-vial technique, Gimenez staining and light microscopy. The infected cell cultures contained rod-shaped particles morphologically identical to rickettsiae. The isolation was confirmed by direct detection of a fragment of the R. helvetica gene for citrate synthase in the positive ticks by PCR and its subsequent cloning, sequencing and comparison with the database.

KEYWORDS

Rickettsia helvetica; isolation; Ixodes ricinus; Slovakia.

Sunlight-enhanced calcareous deposition on cathodic stainless steel in natural seawater

In replicate series of experiments in natural seawater, one in full darkness and the other in a 1:1 diurnal cycle with as little as ~5% of natural solar illumination, sunlight promoted calcareous deposition on cathodic stainless steel surfaces. As exemplified by scanning electron microscopy, the deposit that formed under the natural diurnal cycle, in the presence of photosynthetic biofilms, was composed of finer calcareous crystals that provided more compact and more uniform surface coverage than the one formed in the dark. The light-enhanced deposit also possessed better scale properties, as suggested by X-ray analysis and electrochemical measurements. Sunlight enhancement of calcareous deposition looked all the more conspicuous when day and night regimes were examined independently. These results not only bear important implications for cathodic protection in marine waters, but also provide an intriguing analogy to coral reef calcification.

Growth and characterization of anilinium hydrogen sulfate (AHS) single crystals: an organic nonlinear optical material

Single crystals of anilinium hydrogen sulfate (C(6)H(8)N(+)·HSO(4)(-), AHS) have been grown by slow evaporation solution growth technique using water as a solvent. Powder X-ray diffraction (XRD) study has been carried out to determine the lattice parameters. Fourier transform infrared (FT-IR) and FT-Raman studies confirm the presence of various functional groups present in the grown crystal. The absorption spectrum of the titled crystal shows that the lower cut off wavelength lies at around 300 nm. The thermal analysis (TG/DTA and DSC) and Polarized light thermomicroscopy (PLTM) were carried out to find the thermal stability, melting point and phase transition of the title crystal. The second-order nonlinear optical (NLO) property of the grown crystal has been confirmed by Kurtz-Perry powder technique. First static hyperpolarizability and molecular orbital calculations were carried out using Gaussian 03W program based on B3LYP/3-21G basis set.

Corrosion behaviour and biofouling characteristics of structural steel in the coastal waters of the Gulf of Mannar (Bay of Bengal), India

The corrosion behaviour and biofouling characteristics of structural steel coupons at three different locations in the Gulf of Mannar were studied over a period of 2 years. Oyster fouling was predominant at Tuticorin open sea, while barnacle fouling was more pronounced at Mandapam and Tuticorin harbour. Among the three locations, Tuticorin open sea showed a markedly higher biomass, particularly after 12 and 18 months. The extent of crevice corrosion caused by hard foulers was more pronounced at Tuticorin harbour when compared to that at the other two locations. The corrosion rate of the structural steel coupons for 24 months was in the order, Mandapam > Tuticorin harbor > Tuticorin open sea. The loss in tensile strength at 12 and 24 months was in the order, Tuticorin open sea > Tuticorin harbor > Mandapam. The corrosion behaviour of the structural steel coupons was strongly influenced by the variations in the biofouling assemblage at the three different coastal locations.

Development of polyvinyl chloride biofilms for succession of selected marine bacterial populations

Present investigation was made to bring out the pattern of biofilm formation by heterotrophic bacteria on nontoxic material, polyvinyl chloride (PVC) sheet fitted wooden rack that was immersed in seawater and the study was conducted in Tuticorin coast. Samplings were made over a period of 7 days with the following time period intervals: 30 min, 1, 2, 4, 24, 48, 72, 96, 120 and 144 hr. Bacterial enumeration was made by spread plate method on nutrient agar medium and characterization of bacterial isolates up to generic level was done. Gram-negative bacteria like Pseudomonas sp., Enterobacter sp., Aeromonas sp., Cytophaga sp. and Flavobacterium sp. were found to be the pioneer in colonizing the surface within 30 min and seven genera were represented in the biofilm. Among them two genera were found belonging to Gram-positive groups which included Micrococcus and Bacillus sp. The early stage biofilm i.e. up to 24th hr was wholly constituted by Gram-negative groups. However, the population density of Pseudomonas sp. was found to be higher (315 CFU) when compared to other Gram-negative forms. Occurrence of Gram-positive group was noted only at 48th hr old biofilm (28 to 150 CFU). The period between 48 and 96th hr was the transition where both the Gram-negative and Gram-positive groups co- existed. After 96th hr, the biofilm was found constituted only by Gram-positive groups. The isolates of early stage biofilm were found to produce allelopathic substance like bacteriocin.

The influence of sunlight on the localized corrosion of UNS S31600 in natural seawater

Tests were conducted on the performance of UNS S31600 stainless steel (SS) in a natural day/night cycle vs full darkness under conditions of natural marine biofilm accumulation. In quiescent flowing seawater tests in the laboratory as well as under natural immersion in the sea, diffuse sunlight (∼10% of natural) counteracted the influence of marine biofilms and produced substantial inhibition of the corrosion of SS. Thus, the probabilities (percentage attack) and propagation rates (depths of attack) in multiple crevice tests were substantially lower in the day/night cycle than in the dark. A benefit was also observed for welded SS in terms of the time to corrosion initiation and the mass loss. SS in the passive state showed broader passive regions, well-defined breakdown potentials and markedly smaller anodic and cathodic current densities under the diurnal cycle. The overall reduction in corrosion is attributed to a combination of electrochemical photoinhibition and simultaneous photoinactivation of microbially mediated metal redox reactions linked to cathodic kinetics. These data offer fresh insights into the behaviour of SS under practical seawater situations and the proposed potential use of illumination in the mitigation of biologically influenced consequences.

Correlated heterogeneous deformation of entangled fiber networks

We study the deformation of a network of entangled non-cross-linked semiflexible fibers subjected to compression. We show that the deformation is intermittent, heterogeneous, and dominated by the occurrence of avalanches. Avalanches imply relative fiber sliding and rearrangement and lead to a serrated stress-strain curve. A large fraction of the fibers in the system contribute to an avalanche, and the amplitudes of the sliding events are correlated spatially. This phenomenon is qualitatively similar in systems with and without friction between fibers and is not due to frictional stick slip.

A novel in silico approach to identify potential therapeutic targets in human bacterial pathogens

In recent years, genome-sequencing projects of pathogens and humans have revolutionized microbial drug target identification. Of the several known genomic strategies, subtractive genomics has been successfully utilized for identifying microbial drug targets. The present work demonstrates a novel genomics approach in which codon adaptation index (CAI), a measure used to predict the translational efficiency of a gene based on synonymous codon usage, is coupled with subtractive genomics approach for mining potential drug targets. The strategy adopted is demonstrated using respiratory pathogens, namely, Streptococcus pneumoniae and Haemophilus influenzae as examples. Our approach identified 8 potent target genes (Streptococcus pneumoniae-2, H. influenzae-6), which are functionally significant and also play key role in host-pathogen interactions. This approach facilitates swift identification of potential drug targets, thereby enabling the search for new inhibitors. These results underscore the utility of CAI for enhanced in silico drug target identification.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s11568-011-9152-7) contains supplementary material, which is available to authorized users.

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.