Analyzing organophosphate pesticide-serum albumin binding interaction: a combined STD NMR and molecular docking study.

In Vitro analysis of the interaction of organophosphate pesticides (OP) with bovine serum albumin (BSA) is crucial to understand their potential effects at the molecular level. In this context, we have employed Saturation Transfer Difference (STD) NMR experiments in conjunction with molecular docking studies to unravel the binding interaction of the OP chlorpyrifos (CPF), diazinon (DZN) and parathion (PA) in solution. The relative STD (%) suggested the detailed epitope mapping of these OP with BSA while the concentration-dependent STD NMR studies were performed to obtain the complex dissociation constant (KD) of the OP-BSA complexes; KD=1.81 × 10-4 M, 1.30 × 10-3 M and 1.11 × 10-3 M for CPF, DZN and PA were extracted respectively. Similar binding modes were identified for all the three OP using STD site-marker experiment. ITC experiments were performed as a complementary method that revealed a high binding affinity of OP-BSA complexes through non-covalent interaction. Molecular docking confirmed the possible interacting chemical groups of OP-BSA complexes. These significant results furnish valuable information about the toxicity risk of OP to proteins.Communicated by Ramaswamy H. Sarma.

In vitro interaction of organophosphate metabolites with bovine serum albumin: A comparative 1H NMR, fluorescence and molecular docking analysis.

Since the exposure of organophosphate pesticides are known to cause severe health consequences, it is important to understand the molecular interaction of these pesticides metabolites with vital biomolecules, especially with the proteins. Here, considering bovine serum albumin (BSA) as a model protein, we have examined its interaction with two selected organophosphate metabolites, 3,5,6-trichloro-2-pyridinol (TCPy) and paraoxon methyl (PM). TCPy and PM are resultant metabolites of two most widely used organophosphate pesticides chlorpyrifos and parathion respectively. 1H NMR line broadening, selective spin-lattice relaxation rate measurements, saturation transfer difference (STD) NMR of both TCPy and PM were carried out in the presence and absence of BSA. The obtained values of the affinity index (A), binding constants (Ka) and thermodynamic parameters indicated strong organophosphates-BSA interaction. Further, fluorescence quenching data on TCPy-BSA and PM-BSA interactions strongly supported the NMR results, besides providing the stoichiometry of these complexes. Molecular docking analysis unraveled viable, strong hydrogen bonds and electrostatic interactions in TCPy-BSA and PM-BSA complexes. This study also revealed substantial time-dependent changes in the 1H NMR intensity of PM in the presence of BSA, which suggests faster degradation of PM with increasing protein concentration during protein-metabolite interactions. The hydrolysis is attributed to the esterase-like action of BSA. The result provides key insights into the direct interaction of the organophosphate metabolites with a biologically important carrier protein, serum albumin.

Supplementation of biotin to sperm preparation medium enhances fertilizing ability of spermatozoa and improves preimplantation embryo development.

PURPOSE: Motility of spermatozoa helps not only in planning the type of infertility treatment but also directly reflects the success rate in assisted reproductive technology (ART). Previously, biotin, a water-soluble vitamin, has been shown to increase the motility and longevity of cryopreserved human spermatozoa. The present study was designed to understand the molecular basis of the beneficial effects of presence of biotin in sperm wash medium on early embryo development. METHODS: The effect biotin supplementation to sperm wash medium on the sperm parameters were assessed in swim-up fraction of normozoospermic and asthenozoospermic ejaculates collected from infertile men. Fertilization and early embryo development was studied using Swiss albino mice. RESULTS: Even though both biotin and pentoxifylline (PTX) enhanced the motility of spermatozoa from normozoospermic and asthenozoospermic samples, biotin group exhibited higher in vitro survival. Using mouse model, we observed that presence of biotin or PTX in sperm wash medium improved the fertilization rate and blastocyst rate compared to control. Blastocysts from these groups had significantly higher total cell number (P < 0.01) and lower apoptotic index. In silico target prediction revealed that GTPase HRas (HRas), tyrosine-protein phosphatase nonreceptor type 1 (PTP1B), and glucokinase are the probable targets for biotin. Solution-state Nuclear Magnetic Resonance (NMR) studies confirmed that biotin interacts both with human HRas and PTP1B. CONCLUSION: Our results indicate that presence of biotin in sperm wash medium can improve the fertilization potential and preimplantation embryo development and can be considered as a safe alternate to PTX.

Solvent-dependent binding interactions of the organophosphate pesticide, chlorpyrifos (CPF), and its metabolite, 3,5,6-trichloro-2-pyridinol (TCPy), with Bovine Serum Albumin (BSA): A comparative fluorescence quenching analysis.

Analysis of the interaction of pesticides and their metabolites with the cellular proteins has drawn considerable attention in past several years to understand the effect of pesticides on environment and mankind. In this study, we have investigated the binding interaction of Bovine Serum Albumin (BSA) with a widely used organophosphorous insecticide chlorpyrifos (CPF), and its stable metabolite, 3,5,6-trichloro-2-pyridinol (TCPy) to provide a comparative analysis of the two molecules by employing various spectroscopic techniques viz., UV-vis absorption, Circular Dichroism (CD), and Fluorescence spectroscopy. The fluorescence quenching studies of BSA emission in two different solvents viz., water and methanol in presence of CPF and TCPy have led to the revelation of several interesting facts about the pesticide-protein interaction. It has been found that both the molecules cause static quenching of BSA emission as seen from the Stern-Volmer constant (Ksv) irrespective of the solvent used for the analysis. While TCPy is a stronger quencher in water, it exhibits comparable quenching capacity with CPF in methanol. The solvent dependent differential binding interaction of the two molecules finally indicates possibility of diverse bio-distribution of the pesticides within human body. The UV-vis and CD spectra of BSA in presence of the test molecules have unravelled that the molecules formed ground state complex that are highly reversible in nature and have minimal effect on the protein secondary structure. Furthermore it is also understood that structural changes of BSA in presence of CPF is significantly higher compared to that in presence of TCPY.

Behaviour management of an anxious child.

Children with dental anxiety may refuse treatment, which can lead to dental emergencies. Behavior management is an essential skill and should be acquired by all members of a dental team treating children. Dental surgery staff should be relaxed, welcoming and friendly. Make the child the centre of attention and smile. Use age-appropriate language and avoid the use of jargon. Decide who will talk to the child and when, as he/she may only be able to listen to one person at a time. Avoid non-dental conversations with colleagues during procedures.

Exposure to high-fluoride drinking water and risk of dental caries and dental fluorosis in Haryana, India.

The present study aimed to determine the prevalence of and relationship between dental caries and dental fluorosis at varying levels of fluoride in drinking water. The study was conducted among 3007 school children in the age group of 12 to 16 years in 2 districts of Haryana having varying fluoride levels in drinking water. Type III examination for dental caries according to the WHO index and dental fluorosis estimation according to Dean's index was done. The prevalence of dental caries decreased from 48.02% to 28.07% as fluoride levels increased from 0.5 to 1.13 ppm, but as the fluoride level increased further to 1.51 ppm, there was no further reduction in caries prevalence, but there was a substantial increase in fluorosis prevalence. The optimum level of fluoride in drinking water was found to be 1.13 ppm, at which there was maximum caries reduction with minimum amount of esthetically objectionable fluorosis.

Internet usage among dental students in north India.

The study was conducted to investigate the extent to which students of two dental schools in northern India make use of internet during their undergraduate course and to assess their attitude towards the internet in general. All undergraduate students were assessed using a specially designed, self-administered questionnaire. Overall, 470 (88.84%) students used the internet. Among the internet users, only 207 (44%) accessed it for academic purposes. Also, 356 (75.7%) found information about dentistry easily accessible, whereas 114 (24.3%) reported difficulty in doing so. The study showed that a good number of Indian dental students are using internet, but they are lagging behind their counterparts in the western world.

Mandibular midline supernumerary tooth associated with agenesis of permanent central incisors: a diagnostic conundrum.

Concomitant hypo-hyperdontia is a rare mixed numeric anomalous condition. The presence of this condition in the same area of dental arch and specifically in the mandibular anterior region is reported very infrequently. This case report presents a case of 20 years old male with congenitally missing permanent mandibular central incisors in conjunction with a mandibular midline supernumerary tooth. Only 3 cases have been documented in English literature till date. The article focuses on the review of mandibular mesiodens and the clarity regarding the usage of the terminology "mesiodens".

Mucosal fixed drug eruption in a patient treated with ornidazole.

BACKGROUND: Therapeutic drugs have been observed to cause a wide spectrum of adverse oral effects such as dry mouth, gingival enlargement, taste disturbance, oral mucosal ulceration, halitosis, etc. OBSERVATIONS: A rare case of intra-oral fixed drug eruption (FDE) induced by ornidazole presenting on the hard palate, an extremely rare site for FDE, in a 40-year-old male is reported. CONCLUSIONS: Ornidazole is a relatively newer 5-nitroimidazole derivative commonly prescribed for Amoebic dysentery in developing countries. FDE is a rare adverse drug effect characterized by onset of round/oval, erythematous macules on the skin or mucosa that can be associated with itching and burning sensation. The exact mechanism causing FDE is unknown.

Current status of disinfection of dental impressions in Indian dental colleges: a cause of concern.

INTRODUCTION: Dentistry is predominantly a field of surgery, involving exposure to blood and other potentially infectious materials and therefore requires a high standard of infection control and safety practice in controlling cross-contamination and occupational exposures to blood- and saliva-borne diseases. METHODOLOGY: A questionnaire survey was conducted in 60 dental colleges throughout India to establish routine methods of treating impressions of the oral cavity for disinfection. An email describing the purpose of the study along with a short questionnaire was sent to one of the teaching faculty of concerned departments of the colleges. Questions were asked regarding availability of materials required to disinfect the impressions, the preferred method to treat the impression, and whether postgraduate courses were offered by the department. RESULTS: The routine method of treating the impression reported by 75.9% of the respondents was washing under running water, while 24.1% of the respondents reported that impressions were treated by chemical disinfectants. CONCLUSION: Strict infection control measures are necessary to ensure the health and safety of dental workers and patients. The present study showed that there is a lack of commitment to high standards of infection control practices in dental colleges in India.