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Biomedical subjects

A Mitra

Publications and source records attributed to A Mitra.

At least 19 recordsLinked to original sources
PubMed2006

Surface activity coefficients of spread monolayers of behenic acid salts at air-water interface.

The pressure-area isotherms of ionized monolayers of behenic acid at air-water interface at pH 12.0 have been obtained from the Langmuir film balance experiments under various physico-chemical conditions. The value of the measured surface pressure at a given area per molecule is equal to the sum of the ideal pressure, cohesive pressure and electrical pressure. The electrical pressure term is regarded as the sum of the pressure originating from the Gouy-Chapman double layer including discrete ion effect, ion binding and monolayer hydration effect. At a given area, the deviation of the measured surface pressure from its ideal value has been calculated in terms of the apparent surface compressibility coefficients, surface fugacity coefficients for gaseous monolayer and surface activity coefficients of solute forming two-dimensional solutions in the monolayer phase respectively. Values of all these coefficients have been calculated for different compositions of the monolayer using non-ideal gas model and Raoult's and Henry's laws modified for two-dimensional non-ideal solutions respectively. Values of these coefficients may be higher or lower than unity depending upon ionic strengths and nature of inorganic salts present in the sub-phase. Using these values of surface activity coefficients, the standard free energies of formation, of spread monolayers of salts of behenic acid have been calculated at different standard states of reference.

Air↗
PubMed2006

Challenge of dose escalation in locally advanced unfavourable prostate cancer using HDR brachytherapy.

In men with locally advanced/high-risk prostate cancer, there is an ongoing challenge to achieve improved results. Dose escalation studies using three-dimensional conformal radiotherapy (3D-CRT) or intensity modulated radiation therapy (IMRT) have shown benefit particularly in the intermediate and poor risk groups of patients. Of concern, however, is the increase in documented rectal toxicity. High-dose rate brachytherapy (HDR-BT) as a boost in combination with external beam radiotherapy (EBRT) is an alternative strategy of dose escalation that can potentially achieve an even higher biological equivalent dose (BED) to the tumour. The results so far are very encouraging for men with poor prognosis disease. Moreover the technique is associated with very low rates of acute and late toxicity.

Brachytherapy↗
PubMed2006

Analyzing toxicity through electrophilicity.

The toxicological structure-activity relationships are investigated using conceptual DFT based descriptors like global and local electrophilicities. In the present work the usefulness of electrophilicity in predicting toxicity of several polyaromatic hydrocarbons (PAH) is assessed. The toxicity is expressed through biological activity data (pIC50) defined as molar concentration of those chemicals necessary to displace 50% of radiolabeled tetrachlorodibenzo-p-dioxin (TCDD) from the arylhydrocarbon (Ah) receptor. The experimental toxicity values (pIC50) for the electron acceptor toxin like polychlorinated dibenzofurans (PCDF) are taken as dependent variables and the DFT based global descriptor electrophilicity index (omega) is taken as independent variable in the training set. The same model is then tested on a test set of polychlorinated biphenyls (PCB). A good correlation is obtained which vindicates the importance of these descriptors in the QSAR studies on toxins. These toxins act as electron acceptors in the presence of biomolecules whereas aliphatic amines behave as electron donors some of which are also taken into account for the present work. The toxicity values of the aliphatic amines in terms of the 50% inhibitory growth concentration (IGC50) towards ciliate fresh-water protozoa Tetrahymena pyriformis are considered. Since there is no global nucleophilicity we apply local nucleophilicity (omegamax+) as the descriptor in this case of training set. The same regression model is then applied to a test set of amino alcohols. Although the correlation is very good the statistical analysis reflects some cross validation problem. As a further check the amines and amino alcohols are used together to form both the training and the test sets to provide good correlation. It is demonstrated that the toxicity of several toxins (both electron donors and acceptors) in the gas and solution phases can be adequately explained in terms of global and local electrophilicities. Amount of charge transfer between the toxin and the biosystem, simulated as nucleic acid bases and DNA base pairs, indicates the importance of charge transfer in the observed toxicity. The major strength of the present analysis vis-à-vis the existing ones rests on the fact that it requires only one descriptor having a direct relationship with toxicity to provide a better correlation. Importance of using the information from both the toxin and the biosystem is also analyzed.

Animals↗
PubMed2006

Corneal deposits and topical ofloxacin--the effect of polypharmacy in the management of microbial keratitis.

PURPOSE: To report six cases of corneal deposits after administration of topical ofloxacin in the treatment of bacterial keratitis. METHOD/RESULT: Six cases of microbial keratitis treated with multiple topical medications, including topical ofloxacin, resulted in corneal precipitates and poor wound healing. In five cases, the precipitates resolved with discontinuation of ofloxacin treatment. However, in one patient, some residual deposits persisted following discontinuation of ofloxacin. The cornea epithelialised, but deposits were identified subepithelially. DISCUSSION: Fluoroquinolone antibiotic drops have been extensively used in bacterial keratitis because of their ease of availability, broad spectrum of activity, and lack of toxicity. While corneal precipitates have been reported with cases of topical ciprofloxacin and norfloxacin, little has been documented on corneal deposits and topical ofloxacin in the treatment of bacterial keratitis. The predisposing factors resulting in corneal deposits and the role of polypharmacy are important features that may impair epithelialisation. Clinical management should be aimed at reducing the toxic environment and promoting ocular surface stability.

Administration, Topical↗
PubMed2006

Ferulic acid esterase production by Streptomyces sp.

Studies were carried out on ferulic acid esterase production using a culture of Streptomyces S10. In optimized condition, enzyme yield was 2.0 mU/ml in MBS medium, containing 1.5% de-starched wheat bran at 30 degrees C and initial pH 6.5 under agitated submerged culture.

Carboxylic Ester Hydrolases↗
PubMed2006

Biotransformation of p-coumaric acid by Paecilomyces variotii.

AIMS: To investigate the biotransformation of p-coumaric acid into p-hydroxybenzoic acid (p-HBA) by Paecilomyces variotii Bainier MTCC 6581. METHODS AND RESULTS: As a result of p-coumaric acid degradation by P. variotii, three phenolic metabolites, p-hydroxybenzaldehyde (p-HBAld), p-HBA and protocatechuic acid were formed. These phenolics were detected using TLC and HPLC. The identity of p-HBA and p-HBAld was further confirmed by mass spectrometry. Various analyses showed that 10.0 mmol l(-1) concentration of p-coumaric acid produced a maximum amount of p-hydroxybenzoic acid, 200 mg l(-1), into the medium at 37 degrees C with high-density cultures. CONCLUSIONS: A catabolic pathway of p-coumaric acid by the fungus P. variotii is suggested for the first time. During the process of p-coumaric acid degradation, p-HBA accumulated in the medium as the major degradation product. SIGNIFICANCE AND IMPACT OF THE STUDY: Microbial degradation of cinnamic acid and hydroxycinnamic acid has continued to be the focus of intensive study. The main goal was to identify the microbial species capable of converting these substances into commercially value-added products such as benzoic acid derivatives or aromatic aldehydes.

Benzaldehydes↗
PubMed2005

Intravenous aminophylline for acute severe asthma in children over two years receiving inhaled bronchodilators.

BACKGROUND: Since the advent of inhaled beta2-agonists, anticholinergic agents and glucocorticoids, the role of aminophylline in paediatric acute asthma has become less clear. There remains some consensus that it is beneficial in children with acute severe asthma, receiving maximised therapy (oxygen, inhaled bronchodilators, and glucocorticoids). OBJECTIVES: To determine if the addition of intravenous aminophylline produces a beneficial effect in children with acute severe asthma receiving conventional therapy. SEARCH STRATEGY: The Cochrane Airways Group register of trials was used to identify relevant studies. The latest search was carried out in December 2004 SELECTION CRITERIA: Randomised-controlled trials comparing intravenous aminophylline with placebo in addition to usual care in children met the inclusion criteria. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed studies and extracted data. Disagreement in the selection of trials was resolved by consensus. Attempts were made to contact authors to verify accuracy of data. MAIN RESULTS: Seven trials met the inclusion criteria (380 participants). Methodological quality was high. All studies recruited children with acute severe asthma and requiring hospital admission. Six studies sought participants who were unresponsive to nebulised short-acting beta-agonist and administered systemic steroids to study participants. In two studies where some children were able to perform spirometry, baseline FEV1 was between 35 and 45% predicted. The addition of aminophylline to steroids and beta2-agonist significantly improved FEV1% predicted over placebo at 6-8 hours, 12-18 hours and 24 hours. Aminophylline led to a greater improvement in PEF% predicted over placebo at 12-18 hours. There was no significant difference in length of hospital stay, symptoms, frequency of nebulsations and mechanical ventilation rates. There were insufficient data to permit aggregation for oxygenation and duration of supplemental oxygen therapy. Aminophylline led to a three-fold increase in the risk of vomiting. There was no significant difference between treatment groups with regard to hypokalaemia, headaches, tremour, seizures, arrhythmias and deaths. AUTHORS' CONCLUSIONS: In children with a severe asthma exacerbation, the addition of intravenous aminophylline to beta2-agonists and glucocorticoids (with or without anticholinergics) improves lung function within 6 hours of treatment. However there is no apparent reduction in symptoms, number of nebulised treatment and length of hospital stay. There is insufficient evidence to assess the impact on oxygenation, PICU admission and mechanical ventilation. Aminophylline is associated with a significant increased risk of vomiting.

Acute Disease↗
PubMed2005

Direct observation of the ... 4+-to-2+ ... [corrected] gamma transition in 8Be.

Electromagnetic transition rates provide an important test for nuclear structure models. The nucleus 8Be exhibits a pronounced alpha-cluster structure and is a building block for more complex cluster nuclei. Here we report on the first observation of the gamma transition between the 4(+) and 2(+) states of 8Be in the 4He+4He reaction. The measured on-resonance cross section of 165+/-54 nb leads to a B(E2) of25+/-8e(2) fm(4), in good agreement with alpha-cluster models and sophisticated ab initio structure calculations.

Journal Article↗
PubMed2005

Semiclassical analysis of the nonequilibrium local polaron.

A resonant level strongly coupled to a local phonon under nonequilibrium conditions is investigated. The nonequilibrium Hartree-Fock approximation is shown to correspond to approximating the steady state density matrix by delta functions at field values to which the local dynamics relaxes in a semiclassical limit. If multiple solutions exist, all are shown to make nonvanishing contributions to physical quantities: multistability does not exist. Departures from equilibrium are shown to produce decoherence, preventing the formation of a polaron feature in the spectral function. The formalism also applies to the nonequilibrium Kondo problem.

Journal Article↗
PubMed2005

Avoiding free nipple grafts during reduction mammaplasty in patients with gigantomastia.

Excessive breast hypertrophy or gigantomastia (>2000 g excision of tissue per breast) has traditionally been approached with breast amputation and free nipple grafting during reduction mammaplasty procedures. Disadvantages of free nipple grafts include loss of sensation, poor projection, uneven nipple-areolar complex pigmentation, and loss of lactation. We report our experiences utilizing the inferior pedicle technique of reduction mammaplasty with successful preservation of the nipple-areola complex for patients with gigantomastia. Between 2001 and 2003, 15 patients (ages 19--45) were identified with gigantomastia through review of pathology and operative reports. The inferior pedicle technique was performed in all cases by the attending staff assisted by plastic surgery residents. Patients were followed regularly from 1 week up to 1 year postoperatively. All patients reported relief from the physical sequelae of breast hypertrophy. One patient experienced bilateral partial nipple desquamation; she maintained sensation throughout and healed well with moist dressings. Otherwise, there were no complications and all patients achieved satisfactory esthetic outcomes. Our results suggest that inferior pedicle technique can be successfully performed in patients with gigantomastia. Breast amputation with free nipple grafting need not be considered standard practice for this patient population. Maintaining a wider pedicle base and meticulous intraoperative handling of the pedicle may contribute to the increased viability of the nipple-areolar complex during these cases.

Adult↗
PubMed2005

Cutaneous granulomas associated with primary immunodeficiency disorders.

Cutaneous granulomas are uncommon in primary immunodeficiency disorders. We report cutaneous granulomas in a child with ataxia telangiectasia (AT) and compare the clinical course with similar lesions in an adult with common variable immunodeficiency (CVI). A 4-year-old female with AT developed cutaneous granulomas as erythematous plaques. The largest lesion appeared on her left cheek and continued to progress despite treatment with topical and intralesional steroids. Disease control was obtained initially with oral antibiotics and low-dose oral steroids. On cessation of oral steroids, significant relapse of the facial granuloma occurred. Pulsed and then oral steroids were required to stop the disease process leaving significant scarring. The second case is of cutaneous granulomas in a 66-year-old man, with CVI, who presented with an erythematous reticulate rash on the legs. We consider it useful to report this patient here as disease control was obtained in a similar way with systemic immunosuppression. In this patient a combination of oral steroids and azathioprine was used. These cutaneous granulomas are thought to be a manifestation of immune dysregulation. No infectious cause has been found so far. We recommend the use of broad-spectrum antibiotics in conjunction with systemic steroids for progressive granulomas, as these patients are immunosuppressed and infection with an unidentified organism cannot be excluded.

Aged↗
PubMed2005

Differential gene expression of sulindac-treated human breast epithelial cells.

Breast cancer is the most common malignancy and the second major cause of cancer-related deaths among women in the United States. Recent advances in the molecular genetics of breast cancer have identified various genes associated with tumorigenesis. There is evidence that non-steroidal anti-inflammatory drugs, e.g. sulindac, have some anti-proliferative effects on various tumors involving altered p53 function. Most of these studies have been performed with various human colon carcinoma cell lines and few of them focus on non-malignant proliferative human mammary epithelial cell lines. Therefore, the present study was undertaken to analyze the differentially expressed genes of the p53 signaling pathway by means of a gene array for the immortalized human breast epithelial cell line, MCF-10F, treated with sulindac. Out of the total 96 genes, only 17 were altered by the drug treatment. Among these 17 genes, 6 showed significant alteration (Q > 2.0), whereas 11 genes showed moderate alterations. Altered genes included BRCA1 associated protein-1 [ubiquitin carboxy-terminal hydrolase (bap1)]; cell division cycle 2, G1 to S and G2 to M [cdk1(cdc2)]; and DNA-damage-inducible transcript 1 (gadd45), which were down-regulated. However, N-myc gene 1 (rtp), promyelocytic leukemia (pml), and nuclear factor of kappa-light polypeptide gene enhancer in B-cell 3 and p65 [avian (rel A)] were up-regulated. Northern blot analysis confirmed some of these alterations. The alteration of p53 signaling pathway gene markers by sulindac treatment can give us valuable information about the response to drug treatments in a proliferative cell population.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Effect of vermicomposting process on metal content of paper mill solid waste.

In the present study the change in metal content on vermicomposting of paper mill solid waste was studied. On vermicomposting, quantity of iron, zinc and chromium found to be increased whereas quantity of aluminium, copper, manganese, nickel and lead found comparatively low. The bioaccumulation of any metal was not observed in the body of the earthworm, hence after vermicomposting, there is no harm to fishes to utilize earthworm biomass as their food. The metal content in the vermicompost prepared from the paper mill solid waste was well within the permissive limits and can therefore be safely applied in an aquaculture, agriculture and other food production systems.

Agriculture↗