Highly Conducting pi-Conjugated Molecular Junctions Covalently Bonded to Gold Electrodes

We measure electronic conductance through single conjugated molecules bonded to Au metal electrodes with direct Au-C covalent bonds using the scanning tunneling microscope based break-junction technique. We start with molecules terminated with trimethyltin end groups that cleave off in situ resulting in formation of a direct covalent sigma bond between the carbon backbone and the gold metal electrodes. The molecular carbon backbone used in this study consist of a conjugated pi-system that has one terminal methylene group on each end, which bonds to the electrodes, achieving large electronic coupling of the electrodes to the pi-system. The junctions formed with the prototypical example of 1,4-dimethylenebenzene show a conductance approaching one conductance quantum (G0 = 2e2/h). Junctions formed with methylene terminated oligophenyls with two to four phenyl units show a hundred-fold increase in conductance compared with junctions formed with amine-linked oligophenyls. The conduction mechanism for these longer oligophenyls is tunneling as they exhibit an exponential dependence of conductance with oligomer length. In addition, density functional theory based calculations for the Au-xylylene-Au junction show near-resonant transmission with a cross-over to tunneling for the longer oligomers.Comment: Accepted to the Journal of the American Chemical Society as a Communication

Toxicity Assessment of Wild Mushrooms from the Western Ghats, India: An in Vitro and Sub-Acute in Vivo Study

Background: Poisoning by different kinds of toxic mushrooms is unfortunately becoming an increasingly important medical problem, evident from the growing number of reports worldwide since the 1950s. Mycetism being a health concern, deserves scientific attention. In this perspective, the present study aims to assess the potential effects of ingesting the selected wild mushrooms from regions of the Western Ghats, India.Methods: The preliminary cytotoxicity of the selected mushrooms was studied in vitro on the intestinal NCM460 and the Chang's liver cell lines on the basis of cell viability. Further, the hepatotoxicity was assessed by measuring biologically relevant endpoints such as membrane integrity, mitochondrial stress and oxidative status. A 28 day sub-acute toxicity study was carried out by orally administering the mushroom extracts to mice at 250 and 500 mg/kg body weight. The hematological and serum analysis as well as histological examinations were carried out to evaluate their in vivo toxicity. GC-MS analysis of the mushrooms facilitated the identification of their volatile chemical profile.Result: The in vitro intestinal cytotoxicity exhibited by these wild mushrooms in comparison to the edible mushroom indicated their potential gastrointestinal toxicity. The pathological findings in small intestine on exposure to Chlorophyllum molybdites and Agaricus endoxanthus also validates the speculations about their intestinal toxicity. The toxic insult to the hepatocytes due to Amanita angustilamellata, Entoloma crassum, and Clarkeinda trachodes was predictive of the observed in vivo hepatotoxicity which was also accompanied by renal toxicity at the higher dose of 500 mg/kg bwt.Conclusion: The potential toxicity exhibited by these representative mushrooms from the wild warrants caution about their consumption. The present work could also have broader implications for global mycetism

Clinical Evaluation of Pro-Argin and Low Level Laser Therapy in the Treatment of Dentinal Hypersensitivity: A Splitmouth Randomised Clinical Trial

Introduction: Dentinal Hypersensitivity (DH) is the most prevalent condition that causes patients discomfort for patients, leading them to frequently visit dental offices. A wide range of methods and therapeutic procedures have evolved for pain alleviation have evolved. In recent decades, desensitising therapy has been coupled with newer therapies such as Pro-Argin and LowLevel Laser Therapy (LLLT). Pro-Argin therapy occludes the openings of dentinal tubules, while Diode Lasers (DL) cause a melting effect, crystallisation of dentine inorganic components, and coagulation of fluids trapped inside the dentinal tubules, thereby reducing the hypersensitivity. Aim: To compare the efficacy of Pro-Argin and LLLT -475 nm (Bluelase) in providing immediate relief in the treatment of dentinal hypersensitivity. Materials and Methods: This was a double-blind randomised split-mouth clinical trial involving from December 2021 to March 2022, including 12 patients (120 teeth) with bilateral hypersensitivity. They were divided into Group A (Pro-Argin) and Group B (LLLT-475 nm) both with 12 patients and 60 teeth each. Hypersensitivity was recorded using the Schiff cold air sensitivity scale and the Visual Analog Pain Scale (VAS) at baseline and at 15 minutes after desensitising therapy. Results: The study included 12 subjects with bilateral dentinal hypersensitivity, categorised into Group A (Pro-Argin) (Colgate Sensitive Pro-relief) and Group B (LLLT at 475 nm), with 60 teeth each. The Results were assessed using the independent t-test for inter-group comparison and the t-test for intra-group comparison. On inter-group comparison of the Schiff cold air sensitivity score, there was a statistically significant reduction in dentinal hypersensitivity in both the groups (p<0.001) with no statistical significance in VAS scores. However, on intra-group comparison; there was a statistically significant reduction in VAS scores in Group B (p≤0.001). Conclusion: LLLT has provided a significant reduction in dentinal hypersensitivity when compared with Pro-Argin

Genetic association of G896A polymorphism of TLR4 gene in leprosy through family-based and case-control study designs

Background: Polymorphisms in TLR4 may change the function of the protein and alter the efficiency of immune response of host to infection. The high relevance of host gene polymorphisms with outcome of Mycobacterium leprae infection led us to study the genetic association of TLR4 G896A polymorphism in order to identify its risk among contacts of affected leprosy patients. Methods: For case-control study design a total of 628 individuals were recruited; 17 multicase leprosy families which included 32 case-parent trios were considered for family-based study. Genotyping was done using PCR-RFLP method. Results: In case-control study AA genotype was positively associated while GA genotype was negatively associated with leprosy. In family based transmission disequilibrium test (TDT) analysis allele G was found to be over transmitted to the affected individuals. Conclusion: Case-control study suggests that homozygous AA genotype may confer susceptibility and heterozygous GA genotype may confer resistance to leprosy, while allele A was observed to increase risk and that of allele G may confer resistance to leprosy. No strong transmission disequilibrium was detected in family-based TDT analysis, possibly due to lower number of trios. In contrast to case-control data allele G was over transmitted to the affected ones in TDT analysis. To conclude, the frequencies of genotypes in household contacts were almost the same as in leprosy patients, suggesting that contacts with AA genotype may be at higher risk of leprosy and may therefore require prophylactic inputs