Otitis media with effusion in children admitted for adenoidectomy.

This cross-sectional prospective study was done in the Department of Otolaryngology Head & Neck Surgery, Bangabandhu Sheikh Mujib Medical University, Dhaka during the period of January 2008 to December 2009 with the aim to find out the frequency of otitis media with effusion in patients with enlarged adenoid admitted for Adenoidectomy, To see the frequency of otitis media with effusion in different age group, To find out the degree of hearing loss in enlarged Adenoid patients. A total number of 60 patients who were admitted for adenoidectomy with or without tonsillectomy were purposively collected. Male female ratio was 1.6:1. Majority of patients (61.67%) came from lower socioeconomic group. Amongst the patients with enlarged adenoids, OME was found in 32(53.33%) cases. Out of 25 grossly enlarged adenoid cases, OME was found in 19(76%) cases. In 35 cases of moderately enlarge adenoid, OME was found in 13(37.14%) cases. Out of 28 enlarged adenoid cases in age group 0-5 years, OME was present in 19(67.86%) cases and out of 32 enlarge adenoid cases in age group 6-15 years; OME was present in 13(40.62%) cases. Most of the patients presented with multiple clinical features, the commonest was mouth breathing (80%), other features were snoring (58.33%), nasal discharge (56.67%) and hearing impairment (53.33%). In tympanometry, flat curve without peak was found in 25 cases and negative middle ear pressure was seen in 7 cases. Regarding hearing status of patients, 25 cases had a mild to moderate degree of hearing loss and PTA was not done in 7 cases due to lower age group (below 4 years).

Imidacloprid in processed tea and tea liquor.

Imidacloprid is a newly introduced broad-spectrum chloronicotinyl insecticide and will find its way in agricultural production, particularly in Asia. However, information on the fate of imidacloprid in crop plants is lacking. The degradation of imidacloprid in processed CTC tea and tea liquor was investigated in the present study in which imidacloprid was applied at recommended application rate (30.0 g a.i./ha) and twice the recommended application rate (60.0 g a.i./ha) for three consecutive seasons. Imidacloprid was rapidly dissipated in processed tea following first order reaction kinetics at all application rates and had half-lives of 0.91-1.16 d with the residue in tea liquor found to be below detectable limit on 3rd day samples. The study revealed that imidacloprid is safe for human consumption and will not pose any residual toxicity problem.

Interaction energy studies on antibiotics nucleoside analogs 2-azaadenine.

The 2-azaadenine antibiotic is known to be a potent cytotoxic nucleoside analog. Evaluation of the interaction energy of this molecule with nucleic acid bases and base pairs has been performed using a quantum-mechanical perturbation technique. Both in-plane and stacking energies have been computed. These energy values along with their sites of association have been compared with the standard energy values and spatial positions for the nucleic acid bases during transcription. The results have been examined in the light of their biological significance.

Biological activity of 3-deazauridine nucleoside analogue: a theoretical study.

The incorporation model of Sanyal et al. has been used to understand the biological activity of the cytostatic compound 3-deazauridine. The interaction energies of various types of binding pattern of the enterant molecule with nucleic acid fragments have been computed. The energy values and the sites of association of the analogous base, obtained by optimization of energy values as well as the sites of association of nucleic acid bases during the transcription process have been compared. The specificity of the binding of the interacting molecule has been discussed, along with the inhibitory effect of 3-deazauridine. They are in agreement with the experimentally observed evidence.

A theoretical study of acriflavin-DNA binding.

A theoretical study of binding behaviour of acriflavin, a well-known mutagen, with DNA base pairs such as AT, GC, TA and CG has been performed using CNDO/2 method to compute net atomic charges and dipoles located at various centres in acriflavine as well as base pairs. Acriflavine-DNA base pair interactions have been evaluated using second order perturbation method with multicentered multipole approximation. Only minimum energy configurations have been reported. Results have been discussed with a view to obtain a comparative behaviour of other similar dyes like proflavine and acridine orange.

Amsacrine binds in a cooperative manner to deoxyribonucleic acid.

The intercalative binding of the acridine antitumour drug 4'-(9-acridinylamino) methane-sulphonate-m-anisidine, a known inhibitor of nucleic acid synthesis, to native calf thymus DNA has been studied using optical titration method. Amsacrine (AMSA) exhibits positive cooperativity in their equilibrium binding to DNA as indicated by the positive slope in the initial region of the binding isotherms (Scatchard plots) under conditions simulating physiological ionic strengths. m-AMSA binds with a higher degree of cooperativity than o-AMSA. Although this correlates with the effectiveness of the drugs as antitumour agents, the exact relationship between the observation of cooperative binding and pharmacological activity is yet to be determined.

Stacking interactions between demethylated ellipticines and DNA base pairs--a quantum mechanical study.

A study of the binding behaviour of ellipticine compounds, derivatives of pyrido (4-3b) carbazole, has been carried out to elucidate the relationship between the drug-activity and demethylation of ellipticine. An all valence electron method (CNDO/2) has been employed to compute molecular charge distribution corresponding to various atomic centres of ellipticines and DNA base pairs. Using these atomic charges and dipoles, intermolecular interaction energy has been calculated with the help of second order perturbation theory and multicentered-multipole expansion technique. A comparative analysis of the binding patterns for nor-5,11-dimethyl-ellipticine and nor-11-methyl-ellipticine has been presented vis-a-vis ellipticine. Attempt has been made to correlate interaction energy studies with demethylation of ellipticine and the possible binding patterns.

Mode of action of intercalators: a theoretical study.

Mode of action of some intercalators has been theoretically investigated on the basis of quantum mechanical perturbation method. Energies of H-bond interaction between drug chromophore and base pairs have been calculated in all possible orientations. The stacking energy has also been calculated with the base pairs. The effect of these interactions on specific recognition has also been discussed. On the basis of these studies, a model for the interaction of these drugs has been proposed. This explains the relative activities of acridine intercalators and satisfies the experimental observations.

Interaction energy studies of an antimetabolite 8-azaguanine during transcription.

The possible incorporation of 8-azaguanine during transcription has been examined in the light of the model of transcription developed earlier by Sanyal et al. Electrostatic energy of interaction has been calculated for the nucleoside analogue (8-azaguanine) base for the entire space inside the deep groove of the DNA double helix. The interaction energy values and the location of the possible sites of association are compared with the recommended configurations of RNA transcription. It is concluded that 8-azaguanine is capable of replacing guanine during transcription. These conclusions are in general agreement with the experimental results.

Molecular basis of drug action of some antibiotics.

A molecular model for the role of nucleoside or nucleotide analogs in drug action has been developed. This model, an extension of our earlier model has been employed to examine the possibility of incorporation of the formycin class of antibiotics (formycin, formycin B and oxoformycin B) in the growing RNA chain. Interaction energy of the analogous bases has been computed for the entire available space inside the deep groove of the DNA double helix. The values of the interaction energy thus computed along with the location of the sites of possible association are compared with the recommended configuration for RNA during transcription. It has been found that only formycin which structurally and energy-wise fulfils the requirement of the model, can successfully replace adenosine during transcription. Results are in agreement with experimental findings.

Role of interaction energy in the specificity of transcription. I-The Watson Crick G-C base pair template.

The purpose of this work is to show that the selectivity of the nucleotide bases in RNA transcription c an be inferred, in principle, from the DNA base pair - RNA base interaction. The catalytic role of enzymes in this process is, therefore, only to form the sugar - phosphate backbone. A systematic study for the evaluation of the interaction energy of the DNA base pair with the enterant RNA bases have been undertaken to elucidate the aforesaid mechanism. Electrostatic hard sphere approximation of Nash and Bradley 1 has been employed. Non bonded induced dipole and London dispersion forces are not taken into account. The present communication gives the results of computations of the interaction energy of the four RNA bases. The results have been discussed with reference to Stent's and Zubay's schemes of RNA transcription.

Role of interaction energy in the specificity of transcription. II-The Watson Crick A-U base pair template.

In continuation with work regarding the evaluation of the energy of association of various RNA bases with various base pairs, the results of the computations of the electrostatic interaction energy of A-U base pair with four RNA bases viz. Adenine, Uracil, Guanine and Cytosine have been reported. Non bonded induced polarization and dispersion potentials are not taken into account. Electrostatic hard sphere model of Nash and Bradley has been employed. Computations have been performed to find out the minimum energy configuration out of the various possible complex configurations. Results have been discussed with reference to similar calculations with G-C base pair performed by the authors.

Interaction of polypeptide hormones with lipid monolayers.

1. The interaction between lipid monolayers spread on the surface of water and oxytocin, [8-arginine]-vasotocin and [1-asparagine-5-valine]-angiotensin II in the subphase was investigated in a Langmuir surface trough by studying the changes in pressure produced on injection of various quantities of the polypeptide solution under the film. 2. The effect of 2m- and 4m-urea on the character of the adsorption is reported. 3. Structures for the adsorbed films formed in this way are suggested. 4. If the lipid monolayer is taken as a suitable model of cell membranes, then it may be supposed that the effect of such structures forming in cell membranes would be to provide effective ;pores' to facilitate the movement of water and other small molecules across the membrane.