Ligand architectural effect on coordination, bonding, interaction, and selectivity of Am(iii) and Ln(iii) ions with bitopic ligands: synthesis, solvent extraction, and DFT studies.

The isolation of Am(iii) ion from Ln(iii) ions is very crucial for the safe disposal of nuclear wastes and thus, studies are being continuously pursued to accomplish this goal. In view of this, herein, a new conformationally rigid bitopic ligand, N,N,N',N'-tetra(2-ethylhexyl)piperazine-di-methylenecarboxamide (PIPDA) has been synthesized and studied for the separation of Am(iii) from Ln(iii) ions. The effect of structural rigidification on the selectivity of Am(iii) over Ln(iii) was compared with an open chain flexible compound, namely, N,N,N',N'-tetra(2-ethylhexyl)-3,6-(N'',N'''-dibutyl)diaza-octane-1,8-diamide (DADA). Two oxygen atoms of the diamide moiety seem to be responsible for controlling the metal ion extraction ability of PIPDA, whereas two nitrogen atoms of the piperazine moiety most probably dictate the separation factor between the Am(iii) and Eu(iii) ions in PIPDA. In addition, scalar relativistic density functional theory (DFT) in conjunction with Born-Haber thermodynamics was used herein to compliment the experimental selectivity. The experimentally observed preferential selectivity of PIPDA for Am(iii) ion over the Ln(iii) ion was corroborated by the computed extraction free energy, ΔGext. The covalent nature of bonding between the metal ions and the ligand was confirmed by analyzing the Mayer bond order and bond character analysis using the atom in molecule concept. Though the conformational rigidity of PIPDA gives stronger interaction than DADA, it does not offer a significant advantage over DADA in terms of the separation factor. The marginal increase in the separation factor for PIPDA over DADA might be attributed to the piperazine nitrogen and to the ligand architecture during complex formation.

DFT and MD simulation supplemented experiments for isotopic fractionation of zinc compounds using a macrocyclic crown ether appended polymeric resin.

Isotope effect is a quantum mechanical phenomenon and thus poses a challenge for the separation of isotopes of an element of interest, especially for heavy elements. Isotopic fractionation of zinc is also quite difficult and challenging but is necessitated due to various applications of its isotopes ranging from nuclear medicine to nuclear power reactors. Here, we developed the dibenzo-18-crown-6 (DB18C6) ether-functionalized poly(methacrylic acid) (PMA) resin by exploiting the ion and isotope recognition ability of the crown ether using DFT/MD simulations followed by experiments for isotopic fractionation of zinc. The PMADB18C6 adsorbent was prepared and suitably characterized. Both computational and experimental findings demonstrate that the adsorption and isotope separation of zinc with PMADB18C6 are due to the molecular recognition effect of the "O" dipole of the crown ether. Furthermore, both MD simulations and experiments suggest Langmuir type adsorption isotherms. The adsorption of Zn2+ ions on the PMA resin is predicted to be endothermic, whereas it is exothermic on the PMADB18C6 resin, as revealed from the experimentally observed enthalpy change. A small scale fixed bed column study was demonstrated to test the scale-up application. The values of the experimental separation factors: 1.0013 for 66/64 and 1.0027 for 68/64 confirm the computationally predicted results of 1.00088 and 1.0010, respectively, thus establishing the combined strength of the theory and experiments for the identification of efficient fractionating agents for a complex quantum isotope effect which eventually helps in planning further experiments in view of medicinal and technological applications of zinc isotopes.

Identification of common virulence factors present in enterotoxigenic Escherichia coli isolated from diarrhoeal patients in Kolkata, India.

AIMS: Development of an effective vaccine against enterotoxigenic Escherichia coli (ETEC) is largely dependent on the conscientious understanding of different virulence associated factors from diverse geographical areas. So, the objective of this study is to elucidate the distribution of enterotoxins, CF and NCVF in clinical ETEC strains isolated between 2008 and 2014 from two hospitals in Kolkata, India. METHODS AND RESULTS: Multiplex PCR method was used for detection of two enterotoxin genes, 11 common CFs and five common NCVFs. Among the 350 tested ETEC strains, 61% strains possessed est+elt genes, 25% est and 14% elt. Among 56% CF positive ETEC strains, CS21 was the prevalent one (37%) followed by CS6 (36%). NCVF genes were present in 59% of the ETEC strains; eatA was the most prevalent (65%) followed by etpA (51%). There were 29% strains negative for any CFs or NCVFs. CONCLUSIONS: We conclude that a pattern exists between CS6, eatA and toxins. We observed est with or without elt, CS6 with or without CS5 and with or without eatA were present in 24% of clinical ETEC strains (59/250) analysed. CS21 has emerged as another predominant CF but it had diverse CFs and NCVFs. SIGNIFICANCE AND IMPACT OF THE STUDY: Prevalence of ETEC virulence factors would help in tracking ETEC globally and suggests the need of a multivalent ETEC vaccine.

Factors associated with diarrhoea in young children and incidence of symptomatic rotavirus infection in rural West Bengal, India.

Socio-behavioural factors and pathogens associated with childhood diarrhoea are of global public health concern. Our survey in 696 children aged ⩽2 years in rural West Bengal detected rotavirus as sole pathogen in 8% (17/199) of diarrhoeic stool specimens. Other organisms were detected along with rotavirus in 11% of faecal specimens. A third of the children with rotavirus diarrhoea, according to Vesikari score, had severe illness. The top four rotavirus genotypes were G9P[4] (28%), G1P[8] (19%), G2P[4] (14%) and G8P[4] (8%). In the multivariate model, the practice of 'drawing drinking water by dipping a pot in the storage vessel' [adjusted odds ratio (aOR) 2·21, 95% confidence interval (CI) 1·03-4·74, P = 0·041], and 'children aged ⩽6 months with non-exclusive breastfeeding' (aOR 2·07, 95% CI 1·1-3·82, P = 0·024) had twice the odds of having diarrhoea. Incidence of rotavirus diarrhoea was 24/100 child-years in children aged >6-18 months, 19/100 child-years in children aged >18-24 months and 5/100 child-years in those aged ⩽6 months. Results have translational implications for future interventions including vaccine development.

Carbon nano tubes functionalized with novel functional group- amido-amine for sorption of actinides.

The manuscript presents the results on the sorption of U(VI), Am(III) & Eu(III) from pH medium by a novel amido-amine functionalized multiwalled carbon nanotube (MWCNT). The novel functional group was introduced in the MWCNT by two step processes and characterized by various instrumental techniques like Scanning Electron Microscopy (SEM), Raman and X-ray Photoelectron Spectroscopy (XPS). The sorption process was found to be highly dependent on the pH of the solution with maximum sorption for both 233U, 241Am & 152+154Eu at pH 7.0. Kinetics of sorption was found to be fast with equilibrium reached in ∼15min and the sorption was found to be following pseudo 2nd order kinetics for the radionuclides. The sorption for both 233U and 152+154Eu followed Langmuir sorption model with maximum sorption capacity of 20.66mg/g and 16.1mg/g respectively. This has been explained by DFT calculations which shows that more negative solvation energy of U(VI) compared to Am(III) and Eu(III) and stronger U-MWCNT-AA complex is responsible for higher sorption capacity of U(VI) compared to Am(III) and Eu(III).The synthesized amido-amine functionalized MWCNT is a very promising candidate for removal of actinides and lanthanides from waste water solution with high efficiency.

Phage typing, biotyping & antimicrobial resistance profile of Salmonella enterica serotype Typhi from Kolkata.

BACKGROUND & OBJECTIVE: Kolkata and its suburbs in eastern India are known to be endemic for typhoid fever. The objective of this study was to determine phage types, biotypes and antimicrobial resistance patterns of Salmonella enterica serotype Typhi isolated during the period 2003-2005 from a prospective surveillance for typhoid fever in two urban slums in Kolkata. METHODS: A total of 195 Salmonella enterica serotype Typhi isolated from blood cultures were phage typed, biotyped and tested for their antimicrobial susceptibility profile. RESULTS: Phage type E1 was the most common (60.3%) followed by phage type A among five phage types identified. Biotype I (95%) was predominant, 28 isolates were multidrug resistant (MDR) and most of the MDR strains belonged to phage type E1 and biotype I. INTERPRETATION & CONCLUSION: A single phage type and biotype were prevalent among the Salmonella enterica serotype Typhi isolates studied from Kolkata, India.

Surface Engineering of PAMAM-SDB Chelating Resin with Diglycolamic Acid (DGA) Functional Group for Efficient Sorption of U(VI) and Th(IV) from Aqueous Medium.

A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH >4) and nitric acid media (>3M). The sorption equilibrium could be reached within 60min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG5-SDB was estimated to be about 682 and 544.2mgg-1 respectively at 25°C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings.

Diclofenac sodium injection sterilized by autoclave and the occurrence of cyclic reaction producing a small amount of impurity.

A known impurity is formed in the production of a parenteral dosage form of diclofenac sodium if terminally sterilized by autoclave. This impurity has been detected as 1-(2,6-dichlorophenyl) indolin-2qone, which is also an intermediate from which diclofenac sodium is generally synthesized. It is only the condition of the autoclave method (i.e., 123 +/- 2 degrees C) that enforces the intramolecular cyclic reaction of diclofenac sodium forming the indolinone derivative and sodium hydroxide. The formation of this impurity has been found to depend on the initial pH of the formulation. The reaction follows first-order kinetics, and the energy of activation is 5.34 kcal/mol. The other excipients in the formulation do not have a role in this reaction. The concentration of the impurity in the resultant product in the ampule goes beyond the limit of the raw materials in the pharmacopoeias. It is thus preferable to use an alternative sterilization method; that is, an aseptic filtration method in which the formation of this impurity can be avoided.

Atypical lymphoid hyperplasia (lymphoid tumour of indeterminate nature) of orbit--a case report.

Atypical lymphoid hyperplasia, a rare variety of orbital tumour occurring in a 60 year old male patient is presented with review of literature with special relation to its diagnostic and prognostic difficulties.

The burden of cholera in the slums of Kolkata, India: data from a prospective, community based study.

AIMS: To conduct a prospective, community based study in an impoverished urban site in Kolkata (formerly Calcutta) in order to measure the burden of cholera, describe its epidemiology, and search for potential risk factors that could be addressed by public health strategies. METHODS: The study population was enumerated at the beginning and end of the study period. Surveillance through five field outposts and two referral hospitals for acute, watery, non-bloody diarrhoea was conducted from 1 May 2003 to 30 April 2004. Data and a stool sample for culture of Vibrio cholerae were collected from each patient. Treatment was provided in accordance with national guidelines. RESULTS: From 62 329 individuals under surveillance, 3284 diarrhoea episodes were detected, of which 3276 (99%) had a stool sample collected and 126 (4%) were culture confirmed cholera. Nineteen (15%) were children less than 2 years of age, 29 (23%) had severe dehydration, and 48 (38%) were hospitalised. Risk factors for cholera included a household member with cholera during the period of surveillance, young age, and lower educational level. CONCLUSIONS: There was a substantial burden of cholera in Kolkata with risk factors not easily amenable to intervention. Young children bear the brunt not only of diarrhoeal diseases in general, but of cholera as well. Mass vaccination could be a potentially useful tool to prevent and control seasonal cholera in this community.

Efficacy of oral hyposmolar glucose-based and rice-based oral rehydration salt solutions in the treatment of cholera in adults.

BACKGROUND: Recent animal experiments and clinical trials have shown that both osmolarity and rice as the organic components are important factors for net intestinal absorption of an oral rehydration salt solution. METHODS: In a controlled clinical trial 123 male adult patients with severe cholera, after initial rehydration with intravenous Ringer's lactate solution, were randomly assigned to receive one of the four oral rehydration salt solutions: WHO ORS, ORS containing 70 mmol/l Na+ and 16.2 g/l glucose, rice ORS containing 50 g/l rice and 90 mmol/l Na+, and rice ORS containing 50 g/l rice and 70 mmol/l Na+. All patients received 300 mg of doxycycline as a single dose. RESULTS: Patients who received rice-low-sodium ORS subsequently had lower (P < 0.05) stool output, ORS consumption, and diarrhoea duration than the other three ORS groups. CONCLUSIONS: We conclude that rice-based low-sodium ORS is superior for treating adult cholera.

Evaluation of oral hypo-osmolar glucose-based and rice-based oral rehydration solutions in the treatment of cholera in children.

UNLABELLED: In a randomized controlled clinical trial, the efficacy of a low-sodium low-glucose oral rehydration solution (ORS) and a low-sodium rice-based ORS was compared with standard WHO glucose ORS in the treatment of severe cholera in children aged 2-10y. In total, 120 children were evaluated for the study, of whom 58 patients were positive for Vibrio cholerae and were included in the study. Of these 58 cases, 19 received rice-based hypo-osmolar ORS, 20 received WHO-ORS and 19 received glucose-based hypo-osmolar ORS. The clinical characteristics (age, preadmission duration of diarrhoea, frequency of stool before admission, incidence of vomiting, body weight and volume of initial fluid requirement) were comparable in the three treatment groups. All patients received tetracycline in a dose of 50 mg/kg/d of body weight in 4 divided doses for 3 d. CONCLUSIONS: Patients who received rice-based hypo-osmolar ORS had subsequently reduced (p < 0.05) stool output, ORS consumption and diarrhoea duration than the patients who received either WHO-ORS or glucose-based hypo-osmolar ORS.