Application of calcifying bacteria for remediation of stones and cultural heritages

Since ages, architects and artists worldwide have focused on usage of durable stones as marble and limestone for construction of beautiful and magnificent historic monuments as European Cathedrals, Roman, and Greek temples, Taj Mahal etc. But survival of these irreplaceable cultural and historical assets is in question these days due to their degradation and deterioration caused by number of biotic and abiotic factors. These causative agents have affected not only the esthetic appearance of these structures, but also lead to deterioration of their strength and durability. The present review emphasizes about different causative agents leading to deterioration and application of microbially induced calcium carbonate precipitation as a novel and potential technology for dealing with these problems. The study also sheds light on benefits of microbial carbonate binders over the traditional agents and future directions

Reducing marble-SO2 reaction rate by the application of certain surfactants

Sulfur dioxide (SO2), prevalent in the modern urban environment of industrial countries, attacks calcite (CaCO3) in marble. As a result, a gypsum (CaSO4.2H2O) crust is produced at rain-sheltered surfaces while areas exposed to rain experience accelerated erosion. We have investigated the effect of certain surfactants as protective agents against SO2 attack. We report that the anions oxalate (C2O4-2) and oleate (C17H33COO-) from solutions of their highly soluble alkali salt species are able to replace carbonate (CO3-2) in calcite producing less reactive substrate of oxalate and oleate of calcium. Experiments to measure the protection obtained by these treatments were carried out in the laboratory and field conditions at nearly 1 ppm and 10 ppb SO2 concentrations, respectively. We found that these treatments provided significant protection to marble exposed in sheltered areas, up to 30% reduction of reaction rate by treatment with 2 × 10-4 M sodium oleate and up to 14% by a 2 × 10-3 M with potassium oxalate solutions, but become ineffective over long term exposure when applied to surfaces exposed to rain. Carrara marble was used in the reported study. Ion chromatography was the analytical tool, which allowed precise measurements of ionic concentrations of these salts, the amount of their uptake by marble, and the thickness of the gypsum crust. X-ray diffraction allowed determination of the new minerals formed at the marble surface by the treatment with surfactants.National Science Foundation for the grant no. BES-971108

Comparison of palonosetron and dexamethasone with ondansetron and dexamethasone for postoperative nausea and vomiting in postchemotherapy ovarian cancer surgeries requiring opioid-based patient-controlled analgesia: A randomised, double-blind, active controlled study

Background and Aims: Patients undergoing ovarian cancer surgery after chemotherapy and requiring opioid-based patient-controlled analgesia (PCA) are at high-risk of postoperative nausea and vomiting (PONV). We aimed to assess the effect of palonosetron and dexamethasone combination for these patients for prevention of PONV. Methods: This study included 2 groups and 150 patients. At the time of wound closure, patients in group A received ondansetron 8 mg intravenous (IV) + dexamethasone 4 mg IV and group B received palonosetron 0.075 mg IV + dexamethasone 4 mg IV. Postoperatively for 48 hours, group A patients received ondansetron 4 mg 8 hourly IV, group B patients received normal saline 8 hourly IV in 2 cc syringe. The primary objective was the overall incidence of PONV. Independent t-test, Chi-square test, and Fisher's exact test were used and multivariate regression analysis was done. Results: Vomiting was significantly higher in group A (37.3%) as compared with group B (21.3%) at 0–48 hours (P = 0.031). Significantly more patients in Group A had nausea as compared with group B at 90–120 minutes (30.66% vs 18.66%, P = 0.043) and 6–24 hours (32.0% vs 22.66%, P = 0.029). PCA opioid usage in microgram was significantly higher in group A at 0–24 hours (690.53 ± 332.57 vs 576.85 ± 250.79, P = 0.024) and 0–48 hours (1126.10 ± 512.18 vs 952.13 ± 353.85, P = 0.030). Conclusion: Palonosetron with dexamethasone is more effective than ondasetron with dexamethasone for prevention of PONV in post-chemotherapy ovarian cancer surgeries receiving opioid-based patient controlled analgesia

Cloning and Characterization of lin Genes Responsible for the Degradation of Hexachlorocyclohexane Isomers by Sphingomonas paucimobilis Strain B90

Hexachlorocyclohexane (HCH) has been used extensively against agricultural pests and in public health programs for the control of mosquitoes. Commercial formulations of HCH consist of a mixture of four isomers, α, β, γ, and δ. While all these isomers pose serious environmental problems, β-HCH is more problematic due to its longer persistence in the environment. We have studied the degradation of HCH isomers by Sphingomonas paucimobilis strain B90 and characterized the lin genes encoding enzymes from strain B90 responsible for the degradation of HCH isomers. Two nonidentical copies of the linA gene encoding HCH dehydrochlorinase, which were designated linA1 and linA2, were found in S. paucimobilis B90. The linA1 and linA2 genes could be expressed in Escherichia coli, leading to dehydrochlorination of α-, γ-, and δ-HCH but not of β-HCH, suggesting that S. paucimobilis B90 contains another pathway for the initial steps of β-HCH degradation. The cloning and characterization of the halidohydrolase (linB), dehydrogenase (linC and linX), and reductive dechlorinase (linD) genes from S. paucimobilis B90 revealed that they share ∼96 to 99% identical nucleotides with the corresponding genes of S. paucimobilis UT26. No evidence was found for the presence of a linE-like gene, coding for a ring cleavage dioxygenase, in strain B90. The gene structures around the linA1 and linA2 genes of strain B90, compared to those in strain UT26, are suggestive of a recombination between linA1 and linA2, which formed linA of strain UT26