QSPR models for polychlorinated biphenyls: n-Octanol/water partition coefficient

The logarithmic n-octanol/water partition coefficient (logK(ow)) is an important property for pharmacology, toxicology and medicinal chemistry. Quantitative structure-property relationship (QSPR) model for the lipophilic behaviour (logK(ow)) of the data set containing 133 polychlorinated biphenyl (PCB) congeners is analyzed using the conceptual density functional theory based global reactivity parameter such as electrophilicity index (omega) along with energy of lowest unoccupied molecular orbital (E(LUMO)) and number of chlorine substituents (N(Cl)) as descriptors. A reasonably good coefficient of determination (r(2) = 0.914) and the internal predictive ability (r(cv)(2) = 0.909) values are obtained indicating the significance of the considered descriptors in the property analysis of PCBs. Further, the developed method has widespread applicability from chemical reactivity to toxicity analysis and in studies related to various physicochemical properties in the series of dioxins and other polyaromatic hydrocarbons.

Careful Scrutiny of the Philicity Concept

The philicity concept [J. Phys. Chem. A 2003, 107, 4973] is put in proper perspective. In the present work we analyze different physicochemical problems using philicity. It provides satisfactory results in all such cases. We also compare the relative electro(nucleo)philicity with philicity to show that philicity is better than relative electro(nucleo)philicity when the intermolecular reactivity trends are considered and there is hardly any preference of one above the other as far as the intramolecular reactivities are concerned. On the contrary, the philicity concept has some advantages over the other concept.

Density Functional Theoretical Investigation on Influence of Heterosubstitution and Benzannelation on the Thermal 6π Electrocyclization of cis-Cyclononatetraene

Thermal 6pi electrocyclization of cyclononatetraene (CNT), its hetero-substituted analogues, and its benzannelated derivatives have been investigated by using the B3LYP method employing 6-31G* and 6-311+G** basis sets. The results indicate that heterosubstitution and benzannelation influence the rate of cyclization. Nucleus independent chemical shifts (NICS), conceptual density functional theory (DFT) based reactivity descriptors, group electronegativity values, and barriers to planarity provide complementary evidence for the predicted rate of cyclization. The available experimental data are in good agreement with the computed values.

Molecular Structure, Reactivity, and Toxicity of the Complete Series of Chlorinated Benzenes

The structure and chemical reactivity profiles of all 12 chlorobenzenes have been investigated using the density functional theory and ab initio molecular orbital calculations. Global and local reactivity descriptors such as electrophilicity index and local philicity, respectively, of the selected systems have been calculated in order to gain insights into the reactive nature and the reactive sites of these compounds. Also, the effects of chlorine substitution on the aromaticity of the compounds have been analyzed by calculating the nucleus-independent chemical shift. Interaction through charge transfer between chlorobenzenes and nucleic acid bases/selected base pairs are determined using Parr's formula. The results revealed that the chlorobenzenes act as electron acceptors in their interaction with biomolecules. Structure-toxicity analysis of this entire set of chlorobenzenes demonstrates the importance of the electrophilicity index in the prediction of reactivity/toxicity.

Hydrothermal Synthesis and Pseudocapacitance Properties of MnO2Nanostructures

The effect of varying the hydrothermal time to synthesize manganese oxide (MnO(2)) nanostructures was investigated along with their influence on structural, morphological, compositional, and electrochemical properties in supercapacitor electrode materials. XRD and TEM studies showed that the MnO(2) prepared in shorter hydrothermal dwell time was a mixture of amorphous and nanocrystalline particles, and there was an evolution of crystallinity of the nanostructures as the dwell time increased from 1 to 18 h. Interestingly, SEM, TEM, and HRTEM revealed a variety of structures ranging from nanostructured surface with a distinct platelike morphology to nanorods depending upon the hydrothermal reaction time employed during the preparation of the manganese oxide: increasing the amount of individual nanorods in the materials prepared with longer hydrothermal reaction time. The surface area of the synthesized nanomaterials varied from 100 to 150 m(2)/g. Electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge studies, and the capacitance values were in the range 72-168 F/g depending upon synthesis conditions. The formation mechanism of the nanorods and their impact on the specific capacitance were discussed in detail.

Quantum chemical studies on polythiophenes containing heterocyclic substituents: Effect of structure on the band gap

Color tuning by the tailoring of substituents at the 3-position of thiophene is very encouraging, and comparative experimental and theoretical studies proved to be powerful in the search for a suitable design for the above. Since the novel polythiophene-based materials substituted with five-membered/six-membered ring containing sulphur and nitrogen at different positions are proven to be potential candidates for electron-transporting hole blocking functions, the structure-property relationship of these systems have been focused in the present study. Molecular-orbital calculations are applied to obtain the optimized geometries and band gaps of the thiophene oligomers. An oligomeric approach has been implemented for calculating the band gaps, and the theoretically obtained band gaps for the different model compounds are compared. Density-functional theory B3LYP6-31G* predicted band-gap values are compared with the experimental band gaps obtained from optical-absorption edge. The predicted values show little deviations from experimental band gaps, but the trend in band gap is found to be the same in experimental and theoretical results in most of the cases. Hence, this study illustrates the usefulness of quantum-mechanical calculations in understanding the effects of various structural parameters on optical band gap.

Stability and Reactivity of All-Metal Aromatic and Antiaromatic Systems in Light of the Principles of Maximum Hardness and Minimum Polarizability

It is demonstrated that among various possible isomers of all-metal aromatic compounds such as Al(4)(2-) and their complexes the most stable isomer with the minimum energy is the hardest and the least polarizable. A similar situation is observed for different isomers of all-metal antiaromatic compounds such as Al(4)(4-) and their complexes. It is shown that linear Al(4)(4-) is energetically more stable than its cyclic isomer. The reaction energies associated with the complexation processes highlight the stability of those complexes. The difference in energy, hardness, and polarizability between a cyclic molecule and its linear counterpart convincingly shows that an aromatic molecule exhibits negative changes in energy and polarizability but positive changes in hardness as expected from the principles of minimum energy, minimum polarizability, and maximum hardness. Although the aromaticity of Al(4)(2-) is unequivocally established through this study, the antiaromaticity picture in the case of Al(4)(4-) is shown to be poorly understood;however, the present analysis sheds light on this controversy.

Stabilization of collagen using plant polyphenol: Role of catechin

Collagen, a unique connective tissue protein finds extensive application as biocompatible biomaterial in wound healing, as drug carriers, cosmetics, etc. A work has been undertaken to study the stabilization of type I collagen using the plant polyphenol catechin. Catechin treated collagen fibres showed a shrinkage temperature around 70 degrees C implying that catechin is able to impart thermal stability to collagen. Catechin treated collagen fibres has been found to be stable even after treatment with high concentration of the secondary structural destabilizer, urea. Circular dichroism studies revealed that there is no major alteration in the structure of collagen on treatment with catechin. The study has demonstrated the involvement of hydrogen bonding and hydrophobic interactions as the major forces involved in the stabilization of collagen by the plant polyphenol, catechin.

Electrophilicity as a possible descriptor for toxicity prediction

Electrophilicity is one of the cardinal chemical reactivity descriptors successfully employed in various molecular reactivity studies within a structure-activity relationship parlance. The applications of this quantity in the modeling of toxicological properties have inspired us to perform a more exhaustive study in order to test and/or to validate the application of electrophilicity in assessing its chemical and toxicological potential. For this reason the toxicity of a large data set of molecules comprising 252 aliphatic compounds on the Tetrahymena pyriformis is studied. A quantitative structure-activity relationship analysis enabled us to model toxicity in terms of global and local electrophilicities, which provide a reasonably good prediction of aliphatic toxicity. It is heartening to note that the global and local electrophilicity values together can explain the toxicity of a large variety of aliphatic compounds nicely without resorting to any other descriptor or other microscopic/macroscopic physicochemical properties as is the situation in all other QSAR studies.

Asbestos problem in India

Primary exposure to asbestos in India can be encountered in the form of asbestos mining, asbestos cement industries, asbestos processing unit and during renovation and demolition of old asbestos cemented roof or other structures as well as modern electrical as well as mechanical appliances in which asbestos is still found. Ultimately construction workers, electricians, vehicle mechanics and other workers in the building trades who are exposed to asbestos inhale hundreds and thousands of amphiboles, which causes lung damage. It is being mined in India at places such as Andhra Pradesh (Pulivendla), Jharkand (Roro), Rajasthan (Ajmer, Bhilwara, Udaipur, Rajsamand) and the common problem faced by the locals are asbestosis through air and fluorosis through drinking water. The problem continues to be in India as well as other developing countries. Also, India import and re-export asbestos to other countries and workers at shipyard, transport of the hazardous material on road and roadside residents all are vulnerable to this uncommon disease. The signs and symptoms generally found with the workers are shortness of breath, persistent and productive cough due to pulmonary fibrosis can show up many years after the asbestos exposure.

Distribution and partitioning of phosphorus in solid waste and sediments from drainage canals in the industrial belt of Delhi, India

Phosphorus is an essential and often limiting nutrient in both marine and freshwater ecosystems. However, its oversupply is of great concern in many environments due to its role in eutrophication. The concentration and distribution of sediment bound phosphorus species not only record its input into the environment, but also suggest their possible sources. It is recognized that the features of phosphorus behaviour have not been extensively studied in urban environments. In this study, phosphorus in solid waste and sediments from drainage canals within the industrial belt of Delhi were fractionated into five operationally defined forms, i.e., exchangeable or loosely sorbed phosphorus (Exch-P), Fe-bound phosphorus (Fe-P), authigenic apatite, CaCO3-bound phosphorus and biogenic apatite (Acet-P), detrital apatite (Det-P) and organic-bound phosphorus (Org-P), in order to assess the potential bioavailability status in these systems.

Peptides Derived from Human Decorin Leucine-rich Repeat 5 Inhibit Angiogenesis

Excessive angiogenesis is involved in many human diseases, and inhibiting angiogenesis is an important area of drug development. There have been conflicting reports as to whether decorin could function as an angiogenic inhibitor when used as an extracellular soluble factor. In this study, we demonstrated that not only purified decorin but also the 26-residue leucine-rich repeat 5 (LRR5) of decorin core protein functions as angiogenesis inhibitor by inhibiting both vascular endothelial growth factor (VEGF) and basic fibroblast growth factor-induced angiogenesis. Peptide LRR5 inhibited angiogenesis through multiple mechanisms, including inhibiting VEGF-stimulated endothelial cell (EC) migration, tube formation on Matrigel, cell attachment to fibronectin, as well as induction of EC apoptosis without significantly affecting their proliferation. We further demonstrated that different subregions of LRR5 inhibited different aspects of angiogenesis, with the middle region (LRR5M, 12 residues) inhibiting endothelial cell tube formation up to 1000 times more potently than LRR5. Although the C-terminal region (LRR5C) potently inhibited VEGF-stimulated endothelial cell migration, the N-terminal region (LRR5N) is as active as LRR5 in inhibiting endothelial cell attachment to fibronectin. Although both LRR5M and LRR5N induced EC apoptosis dose-dependently similar to LRR5 through a caspase-dependent pathway, LRR5C has no such function. We further showed that the inhibition of tube formation by LRR5 and LRR5M is linked with their ability to suppress VEGF-induced focal adhesion kinase phosphorylation and the assembly of focal adhesions and actin stress fibers in ECs, but not their ability to interfere with endothelial cell attachment to the matrix. Circular dichroism studies revealed that LRR5 undergoes an inter-conversion between 3(10) helix and beta-sheet structure in solution, a characteristic potentially important for its anti-angiogenic activity. Peptide LRR5 and its derivatives are therefore novel angiogenesis inhibitors that may serve as prototypes for further development into anti-angiogenic drugs.

Hydrogen Bonding in Phenol, Water, and Phenol−Water Clusters

Structure, stability, and hydrogen-bonding interaction in phenol, water, and phenol-water clusters have been investigated using ab initio and density functional theoretical (DFT) methods and using various topological features of electron density. Calculated interaction energies at MP2/6-31G level for clusters with similar hydrogen-bonding pattern reveal that intermolecular interaction in phenol clusters is slightly stronger than in water clusters. However, fusion of phenol and water clusters leads to stability that is akin to that of H(2)O clusters. The presence of hydrogen bond critical points (HBCP) and the values of rho(r(c)) and nabla(2)rho(r(c)) at the HBCPs provide an insight into the nature of closed shell interaction in hydrogen-bonded clusters. It is shown that the calculated values of total rho(r(c)) and nabla(2)rho(r(c)) of all the clusters vary linearly with the interaction energy.

Electrophilicity index as a possible descriptor of biological activity

The purpose of this study is to probe the suitability of DFT based chemical reactivity parameter, electrophilicity index as a possible biological activity descriptor in the development of QSAR. Testosterone derivatives with activity described in terms of various biological activity parameters and the estrogen derivatives by relative binding affinity (RBA) values have been selected as model systems. The implications for the ability of electrophilicity to describe the biological activities are discussed. From the results it is possible to observe that electrophilicity index may be suitable to effectively describe the biological activity.

Distribution and fractionation of heavy metals in solid waste from selected sites in the industrial belt of Delhi, India

Solid waste samples were collected from five small-scale industrial sites in the National Capital Territory (NCT) of Delhi. These industrial sites represent the regional spread of the industrial belt in the NCT of Delhi. Solid waste samples were digested using aqua-regia and HF in air tight teflon bombs for the quantitative analysis of heavy metals (Hg, Pb, Cd, Mn, Fe, Ni, Cu and Zn) by GBC model 902 atomic absorption spectrophotometer. Hg was analysed using hydrid generator attachment. Beside this sequential extraction was used to fractionate five heavy metals (Pb, Ni, Cd, Cu and Zn) into six operationally defined phases, viz. water soluble, exchangeable, carbonate-bound, Fe-Mn oxides, organic-bound and residual fractions to ascertain the relative mobility of these metals. The result obtained showed metal concentration to be in the range of Hg 0.42-2.3; Pb 23-530; Cd 014-224; Mn 494-19 964; Fe 35 684-233 119; Ni 192-1534; Cu 3065-10 144 and Zn 116-23 321 (all units in mg kg(-1)) in all the industrial areas studied. The fractionated toxic metals like Pb, Ni and Cd were observed to be in the range of 25-35, 15-50 and 40-50%, respectively, in mobile or bio-available fractions of solid waste. As this waste is often disposed-off by the roadsides, low lying areas, abandoned quarries or in landfill sites which are often not properly planned, thus posing potential risk to ground and surface water quality to millions of people living downstream.

Mesoporous SnO2 synthesized with non-ionic surfactants as an anode material for lithium batteries

Mesoporous tin oxides were successfully prepared with the use of non-ionic surfactants, Pluronic 123 (P-123) and Tetronic 908 (T-908). Surface analysis of SnO2 synthesized with P123 showed an average pore size of approximately 15 nm. The high-resolution transmission electron microscopy and low-angle X-ray diffraction (XRD) measurements also confirmed their mesoporous nature. The X-ray photoelectron spectroscopy and wide-angle XRD studies revealed that these compounds have a casserite-type SnO2 structure. The electrochemical properties of these materials as anodes in lithium batteries showed excellent performance with good reversibility. The first-cycle reversible capacity was 1026 mAh/g for the material synthesized with P123. There was a high first-cycle irreversible capacity for SnO2 synthesized with the use of both non-ionic surfactants. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to study the electrode kinetics during the lithium insertion process in the first cycle. There was a decrease in the charge-transfer resistance with respect to the discharge potential. The synthesis and structural and electrochemical properties of the mesoporous tin oxides are correlated and discussed in detail.

The angiogenins: an emerging family of ribonuclease related proteins with diverse cellular functions

Angiogenin is a member of the ribonuclease superfamily, which shows an ever expanding collection of molecules being identified and cloned. It was initially isolated from the conditioned medium of cultured tumour cells. Its angiogenic activity appears to be critical for the maintenance and support of tumour growth. Angiogenin also plays a role in a number of non-malignant vasculoproliferative pathological conditions. Along with other related molecules, it has been identified in a wide variety of somatic tissues in adult and embryonic stages of vertebrate development. This suggests that angiogenin and related molecules are likely to play a vital role in normal physiology. Angiogenin is detectable in serum and to date has been implicated as a mitogen for vascular endothelial cells, an immune modulator with suppressive effects on polymorphonuclear leukocytes, an activator of certain protease cascades such as matrix metalloproteases and plasminogen-activated plasmin pathways, as well as an adhesion molecule. However, the role of the angiogenin family in both normal and abnormal physiology and in development will only fully be realised by genetic approaches involving gene deletion.

Nature of distribution of mercury in the sediments of the river Yamuna (tributary of the Ganges), India

Suspended Particulate Matter (SPM), surface (bed sediments) and short length cores of sediments collected from the largest tributary of the river Ganges, namely the river Yamuna, were analysed for total mercury as well as its fractionation in various size and chemical sites in the sediments following standard procedures. Also, attempts were made to determine the vertical distribution in sediments in relation to the recent timescale of a few decades. Our observations indicate that the SPM in general showed higher levels of total mercury compared to the surface sediments while at places the enhancement could be by a factor of 10, say around 25 microg g(-1) in the downstream region that integrates the industrial midstream and agricultural downstream terrain near its confluence with the Ganges. Surface sediments in the upstream direction near the Himalayan foothills and SPM in the lower reaches showed significant high Index of Geoaccumulation (Igeo) as defined by Müller. Size fractionation studies indicate that the finer fraction preferentially showed higher levels of mercury while in the lower reaches of the river, the total mercury is equitably distributed among all size fractions. The proportion of the residual fraction of mercury in relation to mobile fractions, in general decreases downstream towards its confluence with the Ganges river. In sediment cores, the vertical distribution show systematic peaks of mercury indicating that addition of this toxic metal to the aquatic system is in direct proportion to the increase in various types of human activities such as thermal power plants, land use changes (urbanisation) in the midstream region and intensive fertiliser application in lower reaches of this vast river basin.

Fluoride in fractionated soil samples of Ajmer district, Rajasthan

The natural abundance of fluoride in soils of the Ajmer distict, Rajasthan was examined. From undisturbed soil, the top 15 cm of the profile was examined and the soil split into fractions based on sand, silt and clay particle size. Clay contained a high amount of fluoride, whereas sand and silts are enriched with much less fluoride. The relation between the soil fractions in observed clay fraction fluoride content matched groundwater fluoride variation. However, the enrichment of fluoride material extracted from the largest soil fraction had considerably lower amounts of clay relative to that from the smaller fractions.

A study of the interaction of Cr(III) complexes and their selective binding with B-DNA: a molecular modeling approach

Molecular modeling and energy minimisation calculations have been used to investigate the interaction of chromium(III) complexes in different ligand environments with various sequences of B-DNA. The complexes are [Cr(salen)(H(2)O)(2)](+); salen denotes 1, 2 bis-salicylideneaminoethane, [Cr(salprn)(H(2)O)(2)](+); salprn denotes 1, 3 bis- salicylideneaminopropane, [Cr(phen)(3)](3+); phen denotes 1, 10 phenanthroline and [Cr(en)(3)](3+); en denotes ethylenediamine. All the chromium(III) complexes are interacted with the minor groove and major groove of d(AT)(12), d(CGCGAATTCGCG)(2) and d(GC)(12) sequences of DNA. The binding energy and hydrogen bond parameters of DNA-Cr complex adduct in both the groove have been determined using molecular mechanics approach. The binding energy and formation of hydrogen bonds between chromium(III) complex and DNA has shown that all complexes of chromium(III) prefer minor groove interaction as the favourable binding mode.

Methane emissions from a coastal lagoon: Vembanad Lake, West Coast, India

An attempt has been made to estimate methane fluxes from a tropical coastal wetland the Vembanad Lake, a lagoon along the West Coast of India. It has been found that Vembanad Lake contributes significant amount of methane to the atmosphere. Average emissions varied spatially within the lake. Methane emissions were 193.2 +/- 24.5 mg m(-2) h(-1) at Kumaragam (fresh water) as compared to 9.3 +/- 9.6 mgm(-2) h(-1) at Pullot (brackish water) site. Seasonal variation was significant between pre- and post-monsoons. Soil temperature, time of the day, salinity sediment organic carbon, all control the rate of methane emissions from the Vembanad Lake.

Release of soluble ICAM-5, a neuronal adhesion molecule, in acute encephalitis

BACKGROUND

Intercellular adhesion molecule (ICAM)-5 (telencephalin) is an adhesion molecule in telencephalic neurons of the mammalian brain that binds to the leukocyte integrin CD11a/CD18. The authors observed that human cerebral neurons also expressed ICAM-5 and that ICAM-5--mediated neuron--leukocyte binding in cultured hippocampal neurons. This led the authors to examine ICAM-5 expression during clinical CNS inflammation.

METHODS

The authors found, by immunoblotting, a 115-kDa soluble form of ICAM-5 (sICAM-5) cleaved from the membrane-bound (130 kDa) ICAM-5, and established an ELISA assay to measure it. CSF samples of patients with acute encephalitis and MS were studied.

RESULTS

sICAM-5 was increased in encephalitis (320 plus minus 107 ng/mL; n = 25), as compared with patients with MS (128 plus minus 10 ng/mL; n = 16) and control subjects without CNS disease (137 plus minus 6 ng/mL; n = 42) (p < 0.001). The concentration of sICAM-5 correlated with the performance in the immediate recall task (p = 0.013) and with the leukocyte count in the CSF (p = 0.02), especially in cases caused by herpes simplex virus (HSV) (r = 0.94; p = 0.002).

CONCLUSIONS

sICAM-5 is cleaved from CNS into CSF during acute encephalitis, and it may mediate leukocyte--neuron interactions. sICAM-5 release from cerebral neurons may actively regulate immune responses and leukocyte adhesion during microbial neuroinvasion in humans during encephalitis.

Present status of asbestos mining and related health problems in India--a survey

At present in India more than thirty mines are in operation. It produces 2800 tones of asbestos per month (mainly chrysotile and tremolite) and in recent years substantial quantity (-70%) is imported from Canada. The quality of asbestos produced in India is very poor. The mining and milling and other related processes expose the people to cancer and related diseases. Women are more affected by their exposure in processing unit compared to male who are generally working in mines. Direct and indirect employment in asbestos related industry and mine is around 100,000 workers. Latency period (length of the time between exposure and the onset of diseases) in India is estimated to be 20-37 yr. The causes for lung and breathing problem are mainly due to obsolete technology and direct contact with the asbestos products without proper precaution, because in India asbestos are sold without statutory warning. This paper reviews health effects (such as fibrosis, sequelae, bronchogenic cancer, and malignant mesothelioma) on the Indian mine workers caused due to asbestos mining related activities with respect to their present day condition.

Differentiation potential of intestinal mesenchyme and its interaction with epithelial cells: a study using beta-galactosidase-expressing fibroblast lines

Rat intestinal fibroblast lines (F1:G9 and A1:F1) differing in their potential to support intestinal mucosal development were marked with reporter genes to investigate their differentiation potential. The fibroblasts were transfected with plasmids expressing either beta-galactosidase (with or without a nuclear localisation signal) or green fluorescent protein (GFP). Transfection using Tfx50 or Fugene was more efficient than electroporation. The expression of beta-galactosidase was more stable and stronger than GFP. Cells were optimally labelled using the plasmid pL27B-GAL, and sub-clones with a strong and uniform nuclear expression of beta-galactosidase were isolated. These clones expressed beta-galactosidase even after prolonged passage in the absence of selection. The beta-galactosidase tagged lines (F1:G9gal and A1:F1gal) retained the morphological characteristics, viability and differentiation properties of the parental non-transfected lines. In co-culture with a colorectal tumour cell line Caco-2, the F1:G9gal and A1:F1gal cells differed in their morphological organisation but this did not change their expression of smooth muscle alpha-actin.

Truncation of the Mll gene in exon 5 by gene targeting leads to early preimplantation lethality of homozygous embryos

The mixed lineage leukemia gene (MLL) was originally identified through its involvement in reciprocal translocations in leukemias. MLL codes for a large multidomain protein and bears homology to the Drosophila developmental control gene trithorax in two small domains in the amino terminal region, the central zinc finger domain and the carboxy SET domain. Like the Drosophila trx, MLL has also been shown to be a positive regulator of Hox gene expression. We have targeted Mll (the murine homologue of MLL) in exon 5 causing expression of three truncated in-frame Mll transcripts. These transcripts retain all or some of the AT hook motifs and the DMT domain. This mutant allele causes early in vivo preimplantation lethality of homozygous embryos prior to the 2-cell stage. Embryos cultured in vitro progress to the 2-cell stage, but further development is arrested. The heterozygotes exhibit mild skeletal defects as well as defects in some neuroectodermal derivatives.