Removal of arsenic from water using hardened paste of Portland cement

Portland cement has been used as a new low-cost adsorbent for the removal of arsenic from the water environment. In the batch experiments conducted at an initial concentration of 0.2 mg l(-1) of arsenate, it was found that up to 95% of arsenate could be removed. Kinetic profiles were developed for various conditions. The effect of adsorbent dose, effects of common ions such as Ca2+, Mg2+, Fe3+/Fe2+, Cl-, SO4(2-), NO3(-), PO4(3-) and the effect of pH was studied. Adsorption isotherm studies were performed and it was observed that the Freundlich isotherm was followed with a better correlation than the Langmuir isotherm. Arsenite could also be removed up to approximately 88% using the same material. A new detection method for arsenate/arsenite was developed for routine analysis of arsenic and used during the entire study.

Crystal structure of pimolin, C26H20O8

C26H20O8, triclinic, P̅1̅ (No. 2), a = 9.002(2) Å, b = 9.140(2) Å, c = 14.501(3) Å, α = 104.90(3)°, β = 95.34(3)°, ϒ = 113.83(3)°, V = 1028.2Å3, Z = 2, Rgt(F) = 0.074, wRref(F2) = 0.250, T = 293 K.

Superior chemotherapeutic efficacy of amphotericin B in tuftsin-bearing liposomes against Leishmania donovani infection in hamsters

Chemotherapeutic efficacy of the amphotericin B (Amp B), which is the drug of choice for treatment of the leishmanial infections (kala-azar) that become resistant to the conventional chemotherapy using antimonials, has been examined in the Leishmania donovani infected hamsters after encapsulating the drug in tuftsin-free as well as tuftsin-bearing liposomes. The activity was significantly increased (p < 0.05) by delivering Amp B in tuftsin-free liposomes. This antileishmanial effect of the liposomized Amp B was further increased (p < 0.05) by grafting the natural macrophage-activator tetrapeptide, tuftsin (Thr-Lys-Pro-Arg), on the liposome's surface. This could possibly be attributed to both the enhanced drug tolerance after liposomization as well as to the increased uptake of tuftsin-bearing Amp B-laden liposomes by the macrophages. In addition to the increased efficacy, encapsulation of Amp B in the tuftsin-bearing liposomes also enhanced the drug accessibility to areas (e.g. bone marrow) that are otherwise inaccessible to the free drug. These results further demonstrate the usefulness of tuftsin-bearing liposomes as drug vehicles in treatment of the macrophage-based infections that have been reviewed recently (Agrawal, A.K. and Gupta, C.M. (2000). Tuftsin-bearing liposomes in treatment of macrophage-based infections, Adv. Drug Deliv. Rev., 41, 135-146).

Ultrasonic Speeds and Volumetric Properties of Dipropylene Glycol Monomethyl Ether–n-Alkylamine Mixtures at 298.15 K

The excess molar volume and ultrasonic speed have been measured in dipropylene glycol monomethyl ether + butylamine, dibutylamine, and tributylamine across the entire composition range, at the temperature 298.15 K and atmospheric pressure. The ultrasonic speed values have been combined with those of the excess molar volumes converted to densities to give estimates of the product

Space-time pressure structure of pharyngo-esophageal segment during swallowing

We applied high-resolution manometry with spatiotemporal data interpolation and simultaneous videofluoroscopy to normal pharyngeal swallows to correlate specific features in the space-time intraluminal pressure structure with physiological events and normal deglutitive transsphincteric bolus flow to define normal biomechanical properties of the pharyngo-esophageal (PE) segment. Pressures were recorded by microperfused catheter, and the two-dimensional space-time data sets were plotted as isocontours. On these were superimposed bolus trajectories, anatomic segment movements, and hyo-laryngeal trajectories from concurrent videofluoroscopy. Correlation of the highly reproducible space-time-pressure structure with radiographic images confirmed that primary deglutitive PE segment functions (pressure profile, laryngeal elevation, axial sphincter motion, timing of relaxation, contraction) are accurately discernible from single isocontour pressure visualization. Pressure during bolus flow was highly dependent on axial location within PE segment and time instant. The intrabolus pressure domain, corresponding to the space-time region between bolus head and tail trajectories, demonstrated significant bolus volume dependence. High-resolution manometry accurately, comprehensively, and highly reproducibly depicts the PE segment space-time-pressure structure and specific physiological events related to upper esophageal sphincter opening and transsphincteric flow during normal swallowing. Intrabolus pressure variations are highly dependent on position within the PE segment and time.

Role of arginine 216 in catalytic activity of murine Alpha class glutathione transferases mGSTAl-1 and mGSTA2-2 toward carcinogenic diol epoxides of polycyclic aromatic hydrocarbons

Murine class Alpha glutathione (GSH) transferase A1-1 (mGSTA1-1) is unique among mammalian Alpha class GSTs due to its exceptionally high catalytic activity toward (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], which is the activated metabolite of an environmentally relevant carcinogen, benzo[a] pyrene (BP). However, the molecular basis for high catalytic activity of mGSTA1-1 toward (+)-anti-BPDE is not clear. In the present study, we demonstrate that an arginine residue at position 216, which is conserved in some but not all mammalian class Alpha GSTs, plays an important role in catalytic activity of mGSTA1-1 toward (+)-anti-BPDE and carcinogenic diol epoxides of other environmentally relevant polycyclic aromatic hydrocarbons (PAHs). The catalytic efficiency (k(cat)/K(m)) of mGSTA1-1 for the GSH conjugation of (+)-anti-BPDE (108/mM/s) was reduced by about 58% upon replacement of arginine 216 with alanine (R216A). This was mainly due to a significantly lower V(max) for the R216A mutant of mGSTA1-1 compared with wild-type mGSTA1-1. The R216A mutation also resulted in a statistically significant reduction (>70%) in specific activity of mGSTA1-1 toward racemic anti-diol epoxides of chrysene and benzo[c]phenanthrene (anti-CDE and anti-B[c]PDE, respectively). The catalytic activity of mGSTA2-2, which is a close structural homologue of mGSTA1-1, was also reduced upon R216A mutation. The results of the present study clearly indicate that an arginine residue at position 216 is critical for catalytic activity of mGSTA1-1 and mGSTA2-2 toward carcinogenic diol epoxide metabolites of various PAHs that are abundant in the environment and suspected human carcinogens.

Comparison of the effects of recombinant adenovirus-mediated expression of wild-type p53 and p27Kip1 on cell cycle and apoptosis in SUDHL-1 cells derived from anaplastic large cell lymphoma

Recombinant adenoviruses expressing wild-type p53 (AdWTp53) and p27KiP1 (Adp27) were used to compare the effects on cell cycle and apoptosis in SUDHL-1 cells derived from human anaplastic large cell lymphoma. Cells infected with AdWTp53 and Adp27 showed high level of wild-type p53 and p27KiP1 expression, respectively. The expression of these proteins resulted in G1 arrest after 24 h of infection. Although the cells persisted in G1 arrest in both cell populations after 48 and 72 h of infection, the level of apoptosis assessed by TUNEL analysis was higher in cells infected with AdWTp53. Interestingly, apoptosis was more pronounced in cells infected with Adp27 after the initial 24 h and reached a steady state at 48 and 72 h. A lower MOI of Adp27 resulted in G1 arrest associated with a low level of apoptosis in SUDHL-1 cells after 48 h of infection. This was correlated with lower expression of p27KiP1. We postulate that the time-lag and the different level of apoptosis occurring in SUDHL-1 cells infected with AdWTp53 and Adp27 are clearly related to the intrinsic biochemical pathways solicited. In this context our study provides a model to investigate these pathways and better understand the biology of this particular lymphoma. Our data also support a potential application of Adp27 for gene therapy of this lymphoma similarly to AdWTp53 as previously shown.

Inhibition of HIV-1 virion production by a transdominant mutant of integrase interactor 1

Integase interactor 1 (INI1), also known as hSNF5, is a protein that interacts with HIV-1 integrase. We report here that a cytoplasmically localized fragment of INI1 (S6; aa183-294) containing the minimal integrase-interaction domain potently inhibits HIV-1 particle production and replication. Mutations in S6 or integrase that disrupt integrase-INI1 interaction abrogated the inhibitory effect. An integrase-deficient HIV-1 transcomplemented with integrase fused to Vpr was not affected by S6. INI1 was specifically incorporated into virions and was required for efficient HIV-1 particle production. These results indicate that INI1 is required for late events in the viral life cycle, and that ectopic expression of S6 inhibits HIV-1 replication in a transdominant manner via its specific interaction with integrase within the context of Gag-Pol, providing a novel strategy to control HIV-1 replication.

C-terminal region amino acid substitutions contribute to catalytic differences between murine class alpha glutathione transferases mGSTA1-1 and mGSTA2-2 toward anti-diol epoxide isomers of benzo[c]phenanthrene

The molecular basis for catalytic differences between structurally closely related murine class alpha glutathione (GSH) transferases mGSTA1-1 and mGSTA2-2 in the GSH conjugation of anti-diol epoxide isomers of benzo[c]phenanthrene (anti-B[c]PDE) was investigated. GSH conjugation of both (-)- and (+)-enantiomers of anti-B[c]PDE was observed in the presence of mGSTA1-1 (60 and 40% GSH conjugation, respectively), whereas mGSTA2-2 exhibited a preference for the (-)-anti-isomer (>97%). In addition, the specific activity of mGSTA2-2 toward the (-)-anti-B[c]PDE isomer was relatively higher than that of mGSTA1-1. The amino acid sequences of mGSTA1-1 and mGSTA2-2 differ at 10 positions that are distributed in three sections. Section I contains amino acid residues in positions 65 and 95; section II contains residues in positions 157, 162, and 169, and section III contains residues in positions 207, 213, 218, 221, and 222. Enzyme activity measurements with chimeras of mGSTA1-1 and mGSTA2-2 revealed that amino acid substitutions in section III account for their differential enantioselectivity and catalytic activity toward anti-B[c]PDE. Site-directed mutagenesis of amino acid residues in section III of mGSTA2-2 with corresponding residues of mGSTA1-1 followed by activity measurements of the wild type and mutated enzymes indicates that leucine 207 and phenylalanine 221 may be critical for the high catalytic activity of mGSTA2-2 toward (-)-anti-B[c]PDE. Molecular modeling studies demonstrated that the active site of mGSTA1-1 accommodates both enantiomers of anti-B[c]PDE, whereas the (-)-anti-isomer interacts more favorably with active site residues in mGSTA2-2. The results of this study clearly indicate that amino acid substitutions in the C-terminal region contribute to catalytic differences between mGSTA1-1 and mGSTA2-2 with respect to anti-B[c]PDE.

Evidence of calcium influx across the plasma membrane depends upon the initial rise of cytosolic calcium with activation of IP(3) in rat enterocytes by heat-stable enterotoxin of Vibrio cholerae non-O1

In response to heat-stable enterotoxin of Vibrio cholerae non-O1, the initial rise of cytosolic Ca(2+) occurred with activation of IP(3). Chelation of extracellular Ca(2+) with EGTA and suspension of cells in Ca(2+) free buffer both demonstrated the involvement of internal stores in the rise of [Ca(2+)]i. Cells pretreated with dantrolene resulted in decrease of [Ca(2+)]i response which suggested that the rise of intracellular level of Ca(2+) was mostly due to the mobilization from IP(3) sensitive stores. When the cytosolic Ca(2+) was chelated by loading the cells with BAPTA, NAG-ST could not induce Ca(2+) entry to the cell as assessed by Mn(2+) quenching of fura-2 fluorescence which suggested that calcium influx across the plasma membrane depends upon initial rise of this bivalent cation that maintained the sustained phase of [Ca(2+)]i response. Addition of toxin to the fura-2-loaded cells, preincubated with lanthanum chloride, resulted in reduction of [Ca(2+)]i level with a short duration of irregular sustained phase further suggesting that the influx of Ca(2+) across the plasma membrane might be through the calcium channel.

Speeds of Sound and Isentropic Compressibilities of Ethylene Glycol Dimethyl Ether-n-Alcohol mixtures at 298.15 K

The speeds of sound

Rise in free intracellular calcium in HeLa cells infected with aggregative Klebsiella pneumoniae strains isolated from cases of diarrhoea

BACKGROUND & OBJECTIVES

Klebsiella pneumoniae strains occasionally cause diarrhoea in humans. This study was done to determine the involvement of calcium in the pathogenesis of aggregative K. pneumoniae strains.

METHODS

A total of nine strains of K. pneumoniae were tested for adherence assay in HeLa cell line. A representative strain CO-1215 was used for [Ca2+]i study using Fura-2 fluorescence.

RESULTS

Infection of cultured HeLa cells with aggregative K. pneumoniae strain resulted in five-fold elevation of intracellular level of free calcium ([Ca2+]i) with maximum Ca2+ influx at 3 h after bacterial infection. Chelation of extracellular Ca2+ with [ethylenebis(oxyethylenenitrile)] tetraacetic acid and suspension of cells in Ca2+ free buffer suggested that the rise of Ca2+ in aggregative K. pneumoniae infected HeLa cells was due to influx of Ca2+ from extracellular medium.

INTERPRETATION & CONCLUSIONS

This study showed aggregative adherence in HeLa cells and this adherence leads to influx of extracellular Ca2+. The unrestricted passage of calcium ions across cell membranes could cause phosphorylation of proteins involved in ion transport across the membrane, which could result in secretory diarrhoea. Further work is in progress to study the enterotoxicity of these strains in an in vitro rabbit intestinal model.

Location of the epoxide function determines specificity of the allelic variants of human glutathione transferase Pi toward benzo[c]chrysene diol epoxide isomers

Carcinogenic activity of many polycyclic aromatic hydrocarbons (PAHs) is mainly attributed to their respective diol epoxides, which can be classified as either bay or fjord region depending upon the location of the epoxide function. The Pi class human glutathione (GSH) transferase (hGSTP1-1), which is polymorphic in humans with respect to amino acid residues in positions 104 (isoleucine or valine) and/or 113 (alanine or valine), plays an important role in the detoxification of PAH-diol epoxides. Here, we report that the location of the epoxide function determines specificity of allelic variants of hGSTP1-1 toward racemic anti-diol epoxide isomers of benzo[c]chrysene (B[c]C). The catalytic efficiency (k(cat)/K(m)) of V104,A113 (VA) and V104,V113 (VV) variants of hGSTP1-1 was approximately 2.3- and 1.7-fold higher, respectively, than that of the I104,A113 (IA) isoform toward bay region isomer (+/-)-anti-B[c]C-1,2-diol-3,4-epoxide. On the other hand, the IA variant was approximately 1.6- and 3.5-fold more efficient than VA and VV isoforms, respectively, in catalyzing the GSH conjugation of fjord region isomer (+/-)-anti-B[c]C-9,10-diol-11,12-epoxide. The results of the present study clearly indicate that the location of the epoxide function determines specificity of the allelic variants of hGSTP1-1 in the GSH conjugation of activated diol epoxide isomers of B[c]C.

Activity of allelic variants of Pi class human glutathione S-transferase toward chlorambucil

Clinical efficacy of alkylating anticancer drugs, such as chlorambucil, is often limited by the emergence of drug resistant tumor cells. Increased glutathione (GSH) conjugation (inactivation) of alkylating anticancer drugs or their activated metabolites due to overexpression of the Pi class GSH S-transferase (hGSTP1-1) is believed to be an important mechanism in tumor cell resistance to alkylating agents. Interestingly, the hGSTP1 locus is polymorphic in human populations and involves amino acid residues in positions 104 (isoleucine or valine) and/or 113 (alanine or valine). Here, we report that the allelic variants of hGSTP1-1 significantly differ in their efficiency in catalyzing the GSH conjugation of chlorambucil. Catalytic efficiency of the hGSTP1-1(I104,A113) isoform toward chlorambucil was approximately 2.5-, 7.5- and 15-fold higher compared with I104,V113, V104,A113 and V104,V113 variants of hGSTP1-1, respectively. The results of the present study suggest that hGSTP1-1 polymorphism may be an important factor in GST-mediated tumor cell resistance to some alkylating agents.

Enteroaggregative Klebsiella pneumoniae in association with childhood diarrhoea

A total of 19 strains of Klebsiella pneumoniae isolated as sole pathogen from children with diarrhoea were used to study their virulence mechanism using different assays. Eith strains of K. pneumoniae exhibited aggregative adherence that was distinct from the stacked brick enteroaggregative pattern shown by Escherichia coli. The study suggests the presence of a new virulence mechanism in the pathogenesis of Klebsiella-associated diarrhoea.

Long-term (three years) effect of estrogen replacement therapy on major adverse cardiac events in postmenopausal women after intracoronary stenting

This study examined whether estrogen replacement therapy (ERT) in postmenopausal women impacts intermediate and long-term outcome after successful coronary stenting. Our findings offer evidence that ERT significantly reduces target lesion revascularization after intracoronary stenting in postmenopausal patients who are on ERT before the intervention.

Catalytic efficiencies of allelic variants of human glutathione S-transferase Pi in the glutathione conjugation of alpha, beta-unsaturated aldehydes

The catalytic efficiencies of the allelic variants of human glutathione (GSH) S-transferase Pi (hGSTP1-1), which differ in their primary structures by the amino acids in positions 104 (isoleucine or valine) and/or 113 (alanine or valine), in the GSH conjugation (detoxification) of acrolein and crotonaldehyde have been determined. The k(cat)/K(m) values for hGSTP1-1 isoforms I104,A113 (IA), I104, V113 (IV), V104,A113 (VA) and V104,V113 (VV) toward acrolein were 129+/-3, 116+/-3, 128+/-4 and 92+/-3 mM(-1) s(-1), respectively. The catalytic efficiencies of the hGSTP1-1 variants IA, IV, and VA in the GSH conjugation of acrolein were statistically significantly higher (at P=0.05) compared with the VV isoform. On the other hand, the catalytic efficiencies of the hGSTP1-1 isoforms IA, IV, VA and VV toward crotonaldehyde (16+/-2, 12+/-1, 17+/-2, and 12+/-2 mM(-1)s(-1), respectively) were not statistically significantly different from each other. Our results suggest that hGSTP1-1 polymorphism may be an important factor in differential susceptibility of individuals to the toxic effects of acrolein, which is a widely spread environmental pollutant and generated endogenously during metabolic activation of anticancer drug cyclophosphamide.

Potentiation of benzo[a]pyrene-induced pulmonary and forestomach tumorigenesis in mice by D,L-buthionine-S,R-sulfoximine-mediated tissue glutathione depletion

In vitro studies have suggested that the glutathione (GSH) S-transferase (GST)-catalyzed GSH conjugation is an important mechanism for the detoxification of (+)-anti-7,8-dihydroxy-9, 10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], which is the activated form of the widespread environmental pollutant benzo[a]pyrene (BP). However, in vivo experimental evidence for the importance of GSH/GST system in defense against carcinogenic effects of BP is lacking. We hypothesized that if GSH/GST were to play an important role in the detoxification of (+)-anti-BPDE, the tumorigenic activity of BP would be increased by depleting the levels of GSH, which is the required nucleophilic substrate for GST-catalyzed conjugation reactions. In the present study, we have tested the above hypothesis by determining the effect of D, L-buthionine-S,R-sulfoximine (BSO)-mediated tissue GSH depletion on BP-induced tumorigenesis of the lung and forestomach in female A/J mice. Treatment of mice with three i.p. injections of 2.5 mmol BSO/kg (12 h apart) plus 20 mM BSO in drinking water, resulted in a statistically significant reduction in hepatic, pulmonary and forestomach GSH levels. At the same time, BSO-administration caused a statistically significant increase in BP-induced pulmonary and forestomach tumor multiplicity. To the best of our knowledge, the present study is the first report that provides in vivo experimental evidence for the importance of GSH/GST system in cellular protection against carcinogenic effects of BP.

Involvement of a 70-kb plasmid of the epidemic Shigella dysenteriae type 1 (Dt66) strain in drug-resistance, lipopolysaccharide synthesis, and virulence

The present work characterizes a 70 kb plasmid of the Indian epidemic isolate Shigella dysenteriae type 1 strain Dt66 in relation to virulence and drug-resistance characters. Curing of the plasmids of Dt66 strain by acriflavine (AF) yielded seven groups of AF-cured derivatives. One group of derivatives containing 5 plasmids (70-2.5 kb) as against 6 (120-2.5 kb) in the wild type showed resistance to chloramphenicol, pivmecillinam, streptomycin, and tetracycline (CmrPivrSmrTcr) but sensitivity for ampicillin and nalidixic acid (AmsNals). This derivative when used as donor in conjugation experiments with a plasmidless E. coli KL318 strain (AmsCmsPivsSmrTcsNalr) as recipient, transferred only its 70 kb plasmid into the recipient with concomitant transfer of the CmrPivr phenotype. Both the donor and the transconjugant exhibited a diffuse pattern of adherence and produced keratoconjunctivitis in guinea pigs. Transconjugants contained a 42 kDa lipopolysaccharide band which was absent in recipient. Moreover, both donor and transconjugants showed Congo red binding ability. The results suggest that the 70 kb plasmid of S. dysenteriae Dt66 strain encodes not only Cmr,Pivr character but also is associated with virulence-related characters such as Congo red binding, LPS-biosynthesis, HeLa cell adherence, and keratoconjunctivitis related to virulence.

Physico-chemical characteristics and pollution level of Lake Nainital (U.P., India): role of macrophytes and phytoplankton in biomonitoring and phytoremediation of toxic metal ions

Lake Nainital is the sole source of drinking water for the local people and even to majority of tourists. In background of lake utility and its importance at national level, such study is essential which is focused on toxic metal pollution and current nutrient status of the lake and their magnification by algae and macrophytes. Study has shown that lake water is rich in nutrients which supports growth of many aquatic macrophytes and algal blooms. Besides, water is contaminated with metals like Cr, Cu, Fe, Mn, Ni, Pb and Zn. Concentration of some of them like Fe, Pb and Ni were higher than the recommended maximum permissible limits. Concentration of these metals were also found high in lake sediments. The level of metals amongst various components of lake varied considerably in different season. Plants and algae growing therein accumulated appreciable amount of metals and water roots of Salix being more efficient than others. High metal removing potential of these plants may be significant for biomonitoring studies and could be a useful phytoremediation technology to restore water quality by harvesting submerged and floating biomass inhabiting littoral zone of the lake.

Beta-lactamase-free penicillin amidase from Alcaligenes sp.: isolation strategy, strain characteristics, and enzyme immobilization

Isolation and characterization of a beta-lactamase (EC 3.5.2.6)-free, penicillin amidase (penicillin amidohydrolase, EC 3.5.1. 11)-producing organism is reported. The test strain was isolated by an enrichment technique with a substrate other than penicillins. The isolated strain belongs to the genus Alcaligenes. Phenylacetic acid was found to be the inducer of penicillin amidase. The amidase has a broad substrate spectrum. It is very active against penicillin G and semisynthetic cephalosporins, whereas penicillin V and semisynthetic penicillins acted moderately as a substrate. Immobilized cells of Alcaligenes sp. were shown to act as a reversible enzyme.

The farnesyltransferase inhibitor manumycin A is a novel trypanocide with a complex mode of action including major effects on mitochondria

Eukaryotes modify numerous proteins, including small GTPases of the ras superfamily, with isoprenes as a mechanism for membrane attachment. Inhibition of farnesylation of ras has been successfully exploited to control cell growth, with promise in the clinic for treatment of human tumours. Using an in vitro screen of mammalian farnesyltransferase inhibitors, we have identified manumycin A as potently active against growth of both bloodstream and procyclic forms of Trypanosoma brucei. Other structural classes of farnesyltransferase inhibitors were far less effective. Exposure of T. brucei for brief periods to lethal concentrations of manumycin A resulted in subsequent cell death whilst the concentration required to achieve killing was dependent on serum concentration, suggesting partitioning of manumycin A into hydrophobic cellular sites. Manumycin A did not affect trypanosomal protein and DNA synthesis or cell cycle progression but altered incorporation of prenyl groups into several polypeptides indicating a specific effect on the prenylation without effect on other mevalonate pathway products, most importantly prenyl pyrophosphate levels. Morphological analysis indicated that manumycin A caused significant mitochondrial damage suggesting an additional site of action. Structural analogues of manumycin A containing a quinone were also highly trypanocidal and altered mitochondrial morphology, suggesting interference with electron/proton transport systems. Furthermore, manumycin A also elicited mitochondrial alterations in mammalian cells indicating that the effect is not confined to lower eukaryotes. Manumycin A is well tolerated in vivo but failed to cure experimental trypanosomiasis in mice.

Specificity of murine glutathione S-transferase isozymes in the glutathione conjugation of (-)-anti- and (+)-syn-stereoisomers of benzo[g]chrysene 11,12-diol 13,14-epoxide

Specificities of murine glutathione (GSH) S-transferase (GST) isozymes mGSTA1-1, mGSTA2-2, mGSTA3-3 and mGSTA4-4 (alpha class), mGSTP1-1 (pi class) and mGSTM1-1 (mu class) for GSH conjugation of (-)-anti- and (+)-syn-stereoisomers of benzo[g]chrysene 11, 12-diol 13,14-epoxide (B[g]CDE), the activated metabolites of the environmental pollutant benzo[g]chrysene (B[g]C), have been determined. When GST activity was determined as a function of varying (-)-anti- or (+)-syn-B[g]CDE concentration (10-320 microM) at a fixed saturating concentration of GSH (2 mM), each isozyme obeyed Michaelis-Menten kinetics. mGSTA1-1 was significantly more efficient than other murine GSTs in the GSH conjugation of not only (-)-anti-stereoisomer but also (+)-syn-B[g]CDE. For example, the catalytic efficiency (k(cat)/K(m)) of mGSTA1-1 towards (-)-anti-B[g]CDE was approximately 2.3- to 16.6-fold higher compared with other murine GSTs. Likewise, mGSTA1-1 was approximately 2.7-, 6.7-, 4.4- and 12.4-fold more efficient than mGSTA2-2, mGSTA3-3, mGSTP1-1 and mGSTM1-1, respectively, in catalyzing the GSH conjugation of (+)-syn-B[g]CDE. Interestingly, mGSTA4-4, which also belongs to class alpha, was virtually inactive towards both stereoisomers of B[g]CDE. The results of the present study indicate that murine GSTs, especially alpha class isozymes, significantly differ in their ability to detoxify B[g]CDE stereoisomers and that mGSTA1-1 plays a major role in the detoxification of both (-)-anti- and (+)-syn-B[g]CDE, which among four B[g]CDE stereoisomers are formed from the carcinogen B[g]C as major DNA binding metabolites.

Use of the Shinobi wire in chronic coronary occlusions

Occlusion angioplasty has represented a challenge since the introduction of the procedure. We report the successful use of a new, stiff, highly torquable, Teflon-coated wire, the Shinobi wire, in nine coronary occlusions and have included the detailed description of three representative cases. In the discussion we have reviewed the current literature on devices used in coronary occlusions. Cathet. Cardiovasc. Intervent. 48:100-104, 1999.

Shiga-toxin producing Escherichia coli from healthy cattle in a semi-urban community in Calcutta, India

From October to December 1998, single faecal samples from 67 healthy cattle in a semi-urban community near Calcutta were examined for Shiga toxin producing Esch. coli (STEC) using a multiplex PCR primary screen followed by plating on sorbitol MacConkey agar. STEC was isolated from the faeces of 7 (10.5%) animals. The eight strains isolated belonged to eight serotypes viz, O146:H1, O149:HNT, ONT:H34, ONT:H19, O88:HN, ONT:H2, O82:H8 and O28ac:H21. Bead enzyme linked immunosorbent assay showed that three strains produced Shiga toxin 1, one produced Shiga toxin 2 and four produced both.

Clonal analysis of non-toxigenic Vibrio cholerae O1 associated with an outbreak of cholera

We examined the clonal relationships among eight clinical isolates of non-toxigenic (NT) V. cholerae O1 associated with a cluster of cases of cholera in Warangal, Andhra Pradesh in south India and compared their relatedness to toxigenic O1 strains of classical and E1Tor biotypes and with O139 Bengal strains of V. cholerae by pulsed-field gel electrophoresis (PFGE). Phylogentic analysis of the NotI restriction fragment length polymorphism showed that all the NT. V. cholerae O1 strains formed a tight cluster with more than 80 per cent similarity. Interestingly, the NT V. cholerae O1 cluster was more closely related to V. cholerae O139 than to classical and E1Tor biotypes of V. cholerae O1 indicating closer genetic relationships between NT V. cholerae 01 and O139 Bengal strains that were isolated during the same time-frame.

Gender related differences in ATP-dependent transport of dinitrophenyl-glutathione conjugate across murine canalicular liver plasma membrane

The present study reports gender related differences in ATP-dependent transport of dinitrophenyl-glutathione (GSH) conjugate (DNP-SG), a model GSH xenobiotic conjugate, across murine canalicular liver plasma membrane (cLPM). ATP-dependent transport of DNP-SG across female A/J mouse cLPM was mediated by two components, a high-affinity and a low-affinity component, with corresponding Km of 18 microM (Vmax 0.02 nmol/min.mg) and 500 microM (Vmax 0.23 nmol/min.mg), respectively. On the other hand, only one component for the ATP-dependent transport of DNP-SG was observed in male mouse cLPM (K(m) 130 microM; Vmax 0.18 nmol/min.mg). Moreover, the rate of ATP-dependent transport of DNP-SG was markedly higher in the cLPM fraction of male mouse compared with that of the female. Presence of two transport components in female mouse cLPM, but only one system in the cLPM fraction of male mouse, was confirmed by measuring DNP-SG mediated stimulation of ATP hydrolysis (DNP-SG ATPase activity). To the best of our knowledge, the present study is the first report on gender related differences in ATP-dependent murine canalicular transport of GSH conjugates.

Brachydactyly type B: clinical description, genetic mapping to chromosome 9q, and evidence for a shared ancestral mutation

Autosomal dominant brachydactyly type B (BDB) is characterized by nail aplasia with rudimentary or absent distal and middle phalanges. We describe two unrelated families with BDB. One family is English; the other family is Canadian but of English ancestry. We assigned the BDB locus in the Canadian family to an 18-cM interval on 9q, using linkage analysis (LOD score 3.5 at recombination fraction [theta] 0, for marker D9S938). Markers across this interval also cosegregated with the BDB phenotype in the English family (LOD score 2.1 at straight theta=0, for marker D9S277). Within this defined interval is a smaller (7.5-cM) region that contains 10 contiguous markers whose disease-associated haplotype is shared by the two families. This latter result suggests a common founder among families of English descent that are affected with BDB.

Catalytic efficiencies of allelic variants of human glutathione S-transferase P1-1 toward carcinogenic anti-diol epoxides of benzo[c]phenanthrene and benzo[g]chrysene

Four allelic variants of glutathione (GSH) S-transferase P1-1 (hGSTP1-1) that differ in their structures at amino acid(s) in position(s) 104 and/or 113 are known to exist in human populations. However, the physiological significance of hGSTP1-1 polymorphism is not fully understood. In this communication, we report that the I104,A113 allele of hGSTP1-1, which is most frequent in human populations, is also most efficient in the GSH conjugation of carcinogenic anti-diol epoxides of benzo[g]chrysene and benzo[c]phenanthrene (anti-BGCDE and anti-BCPDE, respectively). The catalytic efficiency of hGSTP1-1(I104,A113) isoform toward anti-BGCDE, 0.36 mM(-1) x s(-1), was approximately 1.7-fold higher (P < 0.05) compared with hGSTP1-1(V104,V113). Interestingly, the frequency of codon 104-valine alleles is significantly higher in certain cancers compared with codon 104-isoleucine alleles. Like anti-BGCDE, the catalytic efficiency of hGSTP1-1(I104,A113) isoform toward anti-BCPDE was higher by about 1.4- to 2.2-fold (P < 0.05) than those of other hGSTP1-1 variants. These observations are interesting because we have shown previously (Hu, X. et al., Biochem. Biophys. Res. Commun., 238: 397-402, 1997) that the V104,V113 variant, not the I104,A113 isoform, is most efficient in the GSH conjugation of bay-region anti-diol epoxide of benzo(a)pyrene (anti-BPDE), which, unlike anti-BGCDE or anti-BCPDE, is a planar molecule. In conclusion, our results suggest that hGSTP1-1 polymorphism may be an important factor in differential susceptibility of humans to cancers where polycyclic aromatic hydrocarbons are etiological factors and that I104,A113 variant may play a major role in the detoxification of nonplanar, sterically hindered fjord-region diol epoxides (e.g., anti-BGCDE).

Complexity of trypanosomatid endocytosis pathways revealed by Rab4 and Rab5 isoforms in Trypanosoma brucei

Small G proteins of the Rab family are responsible for vesicle fusion and control flux during intracellular transport. Rab5 is important in endosome maturation and Rab4 in recycling of endocytic material. Three Rab5 isoforms identified so far in mammals and three in the yeast genome suggest that conservation of multiple Rab5 isoforms is required for sophisticated regulation of endocytosis. Trypanosoma brucei homologues of Rab5 and Rab4 (TbRab5A and TbRab4) have been identified. Here we report cloning of a second Rab5 homologue, TbRab5Bp. The TbRAB5A and -5B genes are not linked in the genome, and phylogenetic reconstruction indicates that multiple Rab5 isoforms in yeast, mammals, and trypanosomes evolved independently. Northern blots demonstrate that TbRab5A, -5B, and TbRab4 messages are expressed in bloodstream form (BSF) and procyclic forms of the parasite even though endocytosis is not very active in the latter form. mRNA levels of TbRab5A and -4 are constitutive. Multiple-sized TbRab5B messages at very low abundance are detected, with greater expression in BSF. Also, the TbRab5B mRNA has a large 3'-untranslated region suggestive of potentially complex regulation, and therefore TbRab5Bp may be an important regulator of differential endocytosis levels between BSF and procyclic stage parasites. Affinity purified antibodies raised to C-terminal peptide sequences of all three TbRab proteins recognized small vesicular cytoplasmic structures, which for TbRab5Ap and -5Bp are predominantly near the flagellar pocket. TbRab5Bp colocalizes with invariant surface glycoprotein 100 (ISG100), a protein entering the endocytotic pathway in BSF parasites, whereas in procyclic cells populations of vesicles stained with both TbRab5Ap and -5Bp substantially overlap; TbRab5 proteins are therefore components of the endocytotic pathway. TbRab4p localizes to vesicular structures throughout the cytoplasm, with some overlap with TbRab5Bp, but the majority occupying a different compartment to the TbRab5s. Therefore the trypanosome endosomal system has been functionally dissected for the first time; these reagents provide a unique opportunity for manipulation of the protozoan endosomal system to further our understanding of drug uptake mechanisms and virulence.

Differential enantioselectivity of murine glutathione S-transferase isoenzymes in the glutathione conjugation of trans-3,4-dihydroxy-1, 2-oxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene stereoisomers

The kinetics of the glutathione (GSH) conjugation of (+)- and (-)-enantiomers of anti- as well as syn-3,4-dihydroxy-1,2-oxy-1,2,3, 4-tetrahydrobenzo[c]phenanthrene (B[c]PDE) catalyzed by murine GSH S-transferase (GST) isoenzymes has been investigated. Murine GSTs exhibited significant differences in their enantioselectivity toward B[c]PDE stereoisomers. For example, while pi class isoenzyme mGSTP1-1 was virtually inactive toward stereoisomers with 1S configuration [(-)-syn-and (+)-anti-B[c]PDE], these stereoisomers were good substrates for alpha class isoenzyme mGSTA1-2. When GST activity was measured as a function of varying B[c]PDE concentration (10-320 microM) at a fixed saturating concentration of GSH (2 mM), each isoenzyme examined obeyed Michaelis-Menten kinetics with all four B[c]PDE stereoisomers. Alpha class isoenzyme mGSTA4-4 exhibited negligible activity toward all four stereoisomers of B[c]PDE. The catalytic efficiency of mGSTA1-2 was approximately 1.5- to 15-fold higher than other murine GSTs in the GSH conjugation of (-)-anti-B[c]PDE, which among the four B[c]PDE stereoisomers is the most potent pulmonary carcinogen in the newborn mouse model and a potent skin tumor-initiator. While alpha class isoenzymes mGSTA3-3 and mGSTA1-2 were equally efficient in the GSH conjugation of (+)-anti-B[c]PDE, their catalytic efficiencies toward this stereoisomer were significantly higher than those of mGSTP1-1 and mGSTM1-1. Likewise, mGSTA1-2 was relatively more efficient than other GSTs in the GSH conjugation of both enantiomers of syn-B[c]PDE. In summary, our results indicate that (a) murine GSTs significantly differ in their enantioselectivity in the GSH conjugation of B[c]PDE stereoisomers, which may partially account for the observed differences in the carcinogenic potency of B[c]PDE stereoisomers, and (b) mGSTA1-2 and mGSTA3-3 play a major role in the detoxification of B[c]PDE.

Specificities of human glutathione S-transferase isozymes toward anti-diol epoxides of methylchrysenes

The specificities of human glutathione (GSH) S-transferase (GST) isozymes of class alpha (hGSTA1-1), mu (hGSTM1-1) and pi (hGSTP1-1), including the three allelic forms of hGSTP1-1 [hGSTP1-1(I104,A113), hGSTP1-1(V104,A113) and hGSTP1-1(V104,V113)], in catalyzing the GSH conjugation of anti-diol epoxide stereoisomers of 5-methylchrysene (anti-5-MeCDE) have been examined. The specific activities of human GSTs were significantly higher toward (+)-anti-5-MeCDE than toward the (-)-enantiomer of anti-5-MeCDE. All three variants of hGSTP1-1 were significantly more efficient than either hGSTA1-1 or hGSTM1-1 in GSH conjugation of (+)-anti-5-MeCDE. The catalytic efficiencies of hGSTP1-1 variants toward (+)-anti-5-MeCDE were in the order hGSTP1-1(I104,A113) > hGSTP1-1(V104,V113) > hGSTP1-1(V104,A113). The present study suggests that the I104,A113 allele, which is most frequent in human populations, may play a major role in the detoxification of (+)-anti-5-MeCDE. This may point to specificity, because previous studies from our laboratory have shown that the hGSTP1-1(V104,V113) isoform is significantly more efficient than the other two variants of hGSTP1-1 in catalyzing GSH conjugation of (+)-anti-7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], the ultimate carcinogen of benzo[a]pyrene. Even though the mechanism of the differences in the activities of hGSTP1-1 variants toward anti-5-MeCDE versus anti-BPDE remains to be elucidated, it seems that the molecular configuration of the diol epoxide is an important determinant of the activity of hGSTP1-1 isoforms toward polycyclic aromatic hydrocarbon diol epoxides.

Gender-related differences in susceptibility of A/J mouse to benzo[a]pyrene-induced pulmonary and forestomach tumorigenesis

Benzo[a]pyrene (BP) is a suspected human carcinogen and is known to produce tumors in the lung and forestomach of mice. Glutathione (GSH) S-transferases (GST) play a major role in the detoxification of the ultimate carcinogen of BP, (+)-anti-7,8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene ((+)-anti-BPDE). Previous studies have shown gender-related differences in the expression of GST isoenzymes in mice. The present study was designed to test the hypothesis whether gender-related differences in the expression of GST isoenzymes can affect the susceptibility of mice to BP-induced lung and forestomach tumorigenesis. The expression of pi class isoenzyme mGSTP1-1, which is highly efficient in the detoxification of (+)-anti-BPDE, was approximately 3.0- and 1.5-fold higher in the liver and forestomach of male A/J mouse, respectively, as compared with the female. The levels of other major GST isoenzymes, mGSTA3-3 (alpha class), mGSTM1-1 (mu class) and mGSTA4-4 (alpha class), were also significantly higher in the liver of the male mouse as compared with the female. While pulmonary mGSTP1-1 expression did not differ significantly between male and female A/J mice, the expression of mGSTA3-3, mGSTM1-1 and mGSTA4-4 was significantly higher (1.4-4.0-fold) in the lung of the male A/J mouse as compared with the female. At lower concentrations of BP (0.5 mg BP/mouse), the tumor incidence/multiplicity was significantly higher in the lung as well as in the forestomach of female mice as compared with male mice. For example, while 30% of the female mice developed pulmonary tumors 26 weeks after the first 0.5 mg BP administration, none of the male mice had tumors in their lungs. At higher doses of BP (1.5 mg BP/mouse), however, this differential was either abolished or relatively less pronounced. Our results suggest that up to a certain threshold of BP exposure the levels of GST isoenzymes may be an important determinant of susceptibility to BP-induced tumorigenesis in mice.

A pharmacoeconomic analysis of rimexolone for the treatment of ophthalmic inflammatory conditions

Topical steroids are the standard first-line therapy for treating ophthalmic inflammatory conditions. However, potent ophthalmic steroids can lead to an elevation of intraocular pressure (IOP), which can result in greater medical resource utilization and increased costs. We have developed a decision analysis model from a societal perspective to evaluate the costs and consequences of the treatment of ophthalmic inflammatory conditions with two potent topical steroids: prednisolone and rimexolone. Data for the model are based on information from clinical trials, national data-bases, published literature, and responses by ophthalmologists to a questionnaire on treatment patterns for elevated IOP. Three steroid-responsive conditions are examined separately with the model: uveitis; postoperative inflammation following cataract surgery; and other ophthalmic inflammatory conditions (blepharitis, episcleritis, postoperative refractive surgery, and corneal transplant). The model evaluates patients with acute conditions versus those with chronic conditions and those with mild to moderate elevation of IOP versus those with severe elevation of IOP. Although the unit cost of rimexolone is higher than that of prednisolone, use of rimexolone leads to cost savings because the incidence of elevated IOP is decreased. If rimexolone is used instead of prednisolone for the treatment of ophthalmic inflammatory conditions, the estimated cost saved (at 1995 AWP prices) is approximately $10 million across the entire US population. The savings across the health maintenance organization population on an annualized basis is approximately $3.9 million. Even if rimexolone were priced higher than current market charges (at 130% to 150% of the AWP of prednisolone), cost savings ranging from the $2.9 million to $720,000 would accrue with use of rimexolone compared with prednisolone. However if, rimexolone were priced at 160% of the AWP of prednisolone, its use would incur an additional cost of $300,000. The primary medical resource utilized in treating elevated IOP in ophthalmic inflammatory conditions is physician visits. Medications are responsible for only one-fifth to one-third of the total cost of treating elevated IOP. This analysis indicates that rimexolone is associated with decreased medical resource utilization and cost savings to the entire healthcare system.

Cloning, expression, and biochemical characterization of a functionally novel alpha class glutathione S-transferase with exceptional activity in the glutathione conjugation of (+)-anti-7,8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene

The present study describes cDNA cloning, expression, and kinetic characterization of the two subunits of a murine alpha-class glutathione (GSH) S-transferase (GST) isoenzyme (previously designated as GST 9.5), which, unlike other alpha-class mammalian GSTs, is exceptionally efficient in the GSH conjugation of (+)-anti-7,8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene [(+)-anti-BPDE] [X. Hu, S. K. Srivastava, H. Xia, Y. C. Awasthi, and S. V. Singh (1996) J. Biol. Chem. 271, 32684-32688]. The cDNAs for both subunits of GST 9.5 (GST 9.5-1 and GST 9.5-2) were cloned by RT-PCR. The deduced amino acid sequences of GST 9.5-1 and GST 9.5-2 clones were identical to those of mGSTA1 and mGSTA2, respectively. Both these subunits were expressed in Escherichia coli to determine the relationships between recombinant mGSTA1-1 and mGSTA2-2 and corresponding subunits of tissue-isolated GST 9.5. The pI values of recombinant mGSTA1-1 and mGSTA2-2 (9.49 and 9.45, respectively) were similar to that of the tissue-isolated isoenzyme (pI 9.5). The reverse-phase HPLC elution profiles and immunological cross-reactivities of recombinant mGSTA1-1 and mGSTA2-2 were also similar to those of the corresponding subunits of tissue-isolated GST 9.5. The catalytic efficiency of recombinant mGSTA1-1 toward (+)-anti-BPDE, 131 mM-1.s-1, was approximately 9.5-to 655-fold higher compared with tissue-isolated mGSTP1-1, mGSTA3-3, mGSTM1-1, and mGSTA4-4. Moreover, the catalytic efficiency of mGSTA1-1 toward (+)-anti-BPDE was about 3.3-fold higher compared with recombinant mGSTA2-2. The mGSTA1 and/or mGSTA2 subunits were expressed to varying degrees in female A/J mouse tissues. For example, mGSTA1, but not mGSTA2, subunit expression was observed in the skin, which is a target organ for benzo(a)pyrene (BP)-induced cancer in mice. On the other hand, the expression of either mGSTA1 or mGSTA2 subunit could not be detected in the lung, which is another target organ for BP-induced cancer in mice. Interestingly, relatively large amounts of both mGSTA1 and mGSTA2 subunits were detected in the kidney. In conclusion, the results of the present study clearly indicate that the A1-type subunit of GST 9.5 is responsible for its exceptional catalytic efficiency in the GSH conjugation of (+)-anti-BPDE, which is the ultimate carcinogen of widespread environmental pollutant BP.

Self-expanding metal oesophageal endoprostheses, covered and uncovered: a review of 30 cases

OBJECTIVE

Oesophageal self-expanding metal endoprostheses (SEMS, or stents) are recognized as a safe means of palliating dysphagia caused by malignancy. Stent designs that have covered or uncovered walls are now available. The purpose of this study was to compare the outcome of use of these two designs.

DESIGN

Thirty consecutive cases were reviewed. All the patients had been referred over a period of 25 months for palliation of dysphagia caused by malignant obstruction. Either a covered or an uncovered stent was placed in each patient. Palliation of dysphagia, 30 day mortality, mean survival time, and the number of endoscopic re-interventions required, were assessed.

RESULTS

Uncovered Ultraflex stents were used in 14 patients, and Schneider Wallstents were used in 16 patients. Dysphagia improved by one grade or more in 69% of patients. The 30 day mortality was 27%, with an overall mean survival time of 99 days. There was no significant difference between the two groups for these three parameters. Ten patients needed a total of 28 repeat endoscopic procedures to maintain stent patency, with overall rates for each group of 1.64 procedures per patient, for uncovered stents, compared with 0.31 for covered stents (significant at the P < 0.05 level). The number of repeat procedures increased with survival time.

CONCLUSION

The use of covered self-expanding metal oesophageal endoprostheses is associated with a significant reduction in the need for endoscopic reintervention after stent placement.

Secretor status and ankylosing spondylitis

OBJECTIVE

To assess the genetic association between secretor status and ankylosing spondylitis (AS).

METHODS

A restriction digest method for determining secretor status was developed; 166 patients with AS and 216 healthy British white controls were typed for secretor status using this method.

RESULTS

The frequency of nonsecretors among patients with AS (47/166, 28%) was not significantly different from controls (72/216, 33%).

CONCLUSION

Secretor status does not influence susceptibility to AS.