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Biomedical subjects

B Banerjee

Publications and source records attributed to B Banerjee.

At least 19 recordsLinked to original sources
PubMed1999

Benefit of intravenous antispasmodic (hyoscyamine sulfate) as premedication for colonoscopy.

BACKGROUND: We sought to determine whether premedication for colonoscopy with intravenous hyoscyamine sulfate (Levsin) was helpful from the standpoint of the colonoscopist and the patient. METHODS: One hundred sixteen adult patients were randomized to receive either 0.5 mg hyoscyamine sulfate intravenous (n = 57) or placebo (n = 59). After administration of study drug, patients were given meperidine and midazolam. Parameters measured included the time required to reach the cecum, total procedure time, and the endoscopist's perception of the adequacy of sedation, difficulty of insertion, and amount of colonic spasm on insertion and withdrawal. Patients were given a postprocedure questionnaire assessing their experience. RESULTS: In patients receiving hyoscyamine, there was a shorter cecal intubation time (median 9.2 vs. 12.9 minutes; p = 0. 01), shorter total colonoscopy time (median 20.5 vs. 25.0 minutes; p = 0.01), better patient sedation (p = 0.02), easier colonic insertion (p = 0.001), and less spasm on insertion (p = 0.01). No difference was found in the amount of spasm during withdrawal or the total dosages of meperidine or midazolam used. Patients receiving hyoscyamine sulfate reported being more comfortable during their procedures ( p < 0.001) and were more willing to repeat colonoscopy in the future (p = 0.0001). The only adverse effect seen during the study was a 27% incidence of sinus tachycardia that occurred in patients receiving hyoscyamine. CONCLUSIONS: Premedication with intravenous hyoscyamine sulfate was beneficial in terms of the time required for cecal intubation, total procedure time, adequacy of sedation, and scales of patient comfort. However, the high frequency of sinus tachycardia seen with the dose used in our study, which was extremely rapid in two patients, indicates the need for further study before the drug can be recommended as a routine premedication for colonoscopy.

Adolescent↗
PubMed1999

Duodenal somatostatinoma presenting as upper gastrointestinal bleeding.

Duodenal somatostatinoma is a rare cause of upper gastrointestinal bleeding. We report the case of a 55-yr-old woman who presented with upper gastrointestinal hemorrhage due to a duodenal somatostatinoma. We discuss the characteristics of these tumors, and review the literature on diagnostic workup and management.

Duodenal Neoplasms↗
PubMed1999

Conformational and linear B-cell epitopes of Asp f 2, a major allergen of Aspergillus fumigatus, bind differently to immunoglobulin E antibody in the sera of allergic bronchopulmonary aspergillosis patients.

Asp f 2 is a major Aspergillus fumigatus allergen involved in allergic bronchopulmonary aspergillosis. Knowledge of the B-cell epitopes may contribute to the understanding of immunoregulation and immunodiagnosis. To elucidate the immunoglobulin E (IgE) binding epitopes in the linear sequence of Asp f 2, we synthesized decamer peptides spanning the whole molecule of Asp f 2 on derivatized cellulose membranes and evaluated IgE binding in ABPA patient and control sera. Peptides three to five amino acids long were synthesized based on amino acid sequences within the IgE binding regions and evaluated for the specificity of epitope antibody interactions. Nine IgE binding regions were recognized in this protein of 268 amino acid residues. Of the nine epitopes, seven (ATQRRQI, RKYFG, HWR, YTTRR, DHFAD, ALEAYA, and THEGGQ) are present in the hydrophilic regions of Asp f 2. Immunologic evaluation of the three recombinant fragments, Asp f 2A encompassing the N-terminal epitope region, Asp f 2B without N- and C-terminal regions of the protein, and Asp f 2C representing C-terminal epitopes, revealed that either the N- or C-terminal region of the protein is essential for the correct folding and conformation for IgE antibody binding.

Allergens↗
PubMed1998

Immunodominant peptide epitopes of allergen, Asp f 1 from the fungus Aspergillus fumigatus.

Aspergillus fumigatus ribotoxin Asp f 1 is a major allergen with IgE binding activity to serum of a majority of patients with allergic bronchopulmonary aspergillosis (ABPA). The IgE binding epitopes or the T-cell stimulatory peptides of this molecule have not been studied. In the present investigation, we have synthesized linear decapeptides spanning the whole molecule of Asp f 1 and analyzed their IgE binding properties. We have also synthesized peptides based on their possible T-cell stimulatory properties and studied the stimulation of peripheral blood mononuclear cells from ABPA patients and normal controls. Several peptides demonstrated distinct IgE antibody binding response against sera from ABPA patients and proliferative response against peripheral blood mononuclear cells from the patients. From the results, it can be concluded that the carboxy-terminal region of Asp f 1 representing amino acid residues 115-149 involved in both humoral and cell mediated immunoresponses in ABPA.

Allergens↗
PubMed1998

Emission spectra of colonic tissue and endogenous fluorophores.

Autofluorescence emission spectra of normal, adenomatous, and malignant tissues of the colon were compared to that of known fluorophores to indicate the possible causes of tissue fluorescence. Data were collected from normal mucosa (n = 18), adenomatous polyps (n = 32), and adenocarcinoma (n = 18) of the colon. A range of cellular and extracellular fluorophores (elastin, collagen, flavin adenine dinucleotide, nicotinamide adenine dinucleotide, phenylalanine, pyridoxal 5' phosphate, tryptophan, and tyrosine) were similarly examined using a spectrofluorometer with emission and excitation spectrometers. Emission intensities were plotted against wavelength. Wavelengths of peak emission and the width of each peak at half its maximum intensity were measured. Colonic tissue gave four major emission peaks, the wavelengths of which were independent of tissue histology. Tryptophan and collagen type IV appeared to be responsible for two of the peaks. It is possible that NADH may be the cause of a third emission maxima.

Adenocarcinoma↗
PubMed1998

Immunological characterization of Asp f 2, a major allergen from Aspergillus fumigatus associated with allergic bronchopulmonary aspergillosis.

The 37-kDa recombinant protein Asp f 2, encoding an allergen of Aspergillus fumigatus, was expressed in a prokaryotic expression system and immunologically evaluated for its functional and structural properties. The open reading frame for a 310-amino-acid-long protein was shown to encode a signal peptide of 31 amino acids. A native 37-kDa culture filtrate protein and a 55-kDa mycelial glycoprotein (gp55) exhibited complete N-terminal sequence homology to Asp f 2. A GenBank search for homologous proteins revealed 60 and 44% sequence homologies to the cytosolic protein ASPND1 from Aspergillus nidulans and fibrinogen binding protein from Candida albicans, respectively. The glycosylation sites and cysteine molecules are conserved in all the three proteins. The extracellular matrix protein laminin showed a dose-dependent interaction with Asp f 2. This protein, expressed as a major cell-associated protein within 24 h of in vitro fungal culture, comprises 20 to 40% of total fungal protein. Furthermore, both native and recombinant Asp f 2 exhibited specific immunoglobulin (IgE) binding with allergic bronchopulmonary aspergillosis (ABPA) and cystic fibrosis-ABPA patients, whereas A. fumigatus-sensitized allergic asthma and normal control subjects failed to show IgE binding with Asp f 2. These results indicate that Asp f 2 is a major allergen of A. fumigatus exhibiting IgE antibody binding with sera from patients with ABPA. The antigen should be explored further for its potential role in the differential diagnosis of A. fumigatus-associated allergic diseases.

Allergens↗
PubMed1997

IgE from latex-allergic patients binds to cloned and expressed B cell epitopes of prohevein.

Prohevein is one of the major allergens associated with latex allergy. In the present study, we identified IgE binding regions of prohevein, and expressed multiple IgE binding epitopes by selective cloning. These truncated polypeptides were then used to demonstrate IgE in the sera of patients. Decapeptides of prohevein were synthesized on derivatized cellulose membrane with an offset of one amino acid. The IgE reactivity of these linear peptides was evaluated separately using pooled sera from latex-allergic health care workers (HCW) and spina bifida (SB) patients. A total of 10 IgE binding epitopes representing unique as well as shared epitopes from both the N- and C-domains of the prohevein were identified. Recombinant polypeptides were constructed based on the identified epitopes, and clones carrying DNA fragments were overexpressed. These recombinant peptides were evaluated for IgE binding with sera from HCW, SB, and normal individuals. Recombinant prohevein, hevein, and the C-domain exhibited IgE binding in 84, 88, and 40% of HCW sera, respectively, as against reactivity of 84% with crude latex allergens. However, only 48% of the sera from SB patients showed IgE binding with recombinant prohevein, while 56 and 28% had reactivity with recombinant N- and C-domains, respectively. Among the three remaining recombinant peptides of the C-domain, only CA44-103 showed IgE binding with SB patients. The results of the present study suggest that linear IgE epitope analysis and construction of recombinant peptides increase the sensitivity and specificity of the immunodiagnosis of latex allergy and provide more information on the immunopathogenesis of hypersensitivity reaction mediated by type I allergy.

Allergens↗
PubMed1997

Purification of a major allergen, Asp f 2 binding to IgE in allergic bronchopulmonary aspergillosis, from culture filtrate of Aspergillus fumigatus.

BACKGROUND: Most cases of allergic bronchopulmonary aspergillosis (ABPA) are caused by the fungus Aspergillus fumigatus. Successful treatment of this disease depends on early diagnosis with the use of well-characterized and relevant antigens/allergens of the organism. OBJECTIVE: The aim of this study was to purify and characterize relevant proteins from A. fumigatus that could be used in the reliable diagnosis of ABPA. METHODS: Monoclonal antibodies were raised against A. fumigatus culture filtrate antigens. A Concanavalin A nonbinding protein fraction was purified with use of one of the monoclonal antibody immunoaffinity columns. The purified protein was analyzed on sodium dodecylsulfate-polyacrylamide gel electrophoresis gel and Western blots. The sensitivity and specificity of the purified protein were evaluated by RAST and ELISA with sera from 25 patients with ABPA, from 10 with allergic asthma, and from 10 normal control subjects. RESULTS: The 37 kD Concanavalin A nonbinding protein reacted specifically with IgE antibodies in patients with ABPA. Among the 25 patients with ABPA studied, 96% had IgE antibody against the allergen, whereas none of the subjects with allergic asthma who had positive results on the skin prick test or normal control subjects had a reaction. Both RAST and ELISA results exhibited strong correlation with IgE binding. This allergen exhibited N-terminal sequence identity to a recombinant allergen Asp f 2. CONCLUSIONS: A 37 kD protein with complete N-terminal homology to Asp f 2 is a major allergen of A. fumigatus that significantly reacts with IgE antibody in patients with ABPA, but does not elicit reaction in Aspergillus-sensitive subjects with asthma and normal control subjects.

Allergens↗
PubMed1997

Identification of 45 kD antigen in immune complexes of patients of allergic bronchopulmonary aspergillosis.

A glycoprotein antigen with an apparent mw of 45 kD was observed to be predominant in the circulating immune complexes isolated from patients of allergic bronchopulmonary aspergillosis as well as in the immune complexes prepared in vitro. Further characterisation of 45 kD antigen with trypsin showed four immunologically active peptides with mw 43, 36, 33 and 16 kD. Carbohydrate characterization using various lectins (Maackia amurensis agglutinin, Sambucus nigra agglutinin, Peanut agglutinin, Galanthus nivalis agglutinin and Datura stramonium agglutinin) showed presence of both N-linked and O-linked sugar moieties such as mannose, glucose, galactose and N-acetyl glucosamine. Predominant presence of 45 kD antigen in immune complexes, recognition of 45 kD by monoclonal antibodies raised against glycoprotein rich fraction of A. fumigatus and presence of elastinolytic protease activity indicate that 45 kD antigen is probably a potent virulence factor and may be contributing to the pathogenesis of ABPA by its biological as well as immunological activities.

Adult↗
PubMed1997

Anti-interleukin (IL)-4 and -IL-5 antibodies downregulate IgE and eosinophilia in mice exposed to Aspergillus antigens.

The effect of multiple divided doses compared with single-dose injections of antibodies to murine interleukin (IL)-4 and IL-5 in their respective downregulation of IgE and eosinophilia developing in a model of allergic aspergillosis is investigated. BALB/c mice were exposed to Aspergillus fumigatus antigens (Af) before and along with anticytokine antibodies. The kinetics of blood eosinophils, eosinophil peroxidase (EPO) in bone-marrow cells, serum levels of IgE and Af-specific antibodies, Af-induced cytokine production and mRNA, and lung histology were studied. The results indicate that only multiple anti-IL-5 antibodies were effective in maintaining baseline levels of blood eosinophils. Multiple anti-IL-4 antibodies also downregulated eosinophils in the bone marrow, lung, and peripheral blood, although to a lesser extent than in anti-IL-5 antibody-injected mice. Significant correlation between the EPO activity and the eosinophil numbers in anticytokine antibody-treated mice was observed. The different anti-IL-4 antibody treatments downregulated IgE to the same extent. We conclude that multiple divided doses of anti-IL-5 antibodies are required to sustain normal eosinophil levels in murine allergic aspergillosis. This information may be significant in the therapy of pulmonary allergic diseases.

Animals↗
PubMed1997

Gastric Crohn's disease complicated by adenocarcinoma of the stomach: case report and review of the literature.

Patients with Crohn's disease are at increased risk for developing adenocarcinoma of the small bowel and colon. Although several cases of gastric malignancy have been reported in patients with Crohn's disease, the association remains controversial, particularly because most patients have not had gastric Crohn's involvement. We report a patient with long-standing Crohn's disease, with gastric involvement, who developed adenocarcinoma of the gastric outlet. We discuss the association and include a review of the literature.

Adenocarcinoma↗
PubMed1996

Thermodynamics of the interaction of d-tubocurarine with nicotinic receptors of mammalian skeletal muscle in vitro.

Thermodynamic study is important for defining drug receptor interactions, and denervated rat hemidiaphragm is a unique preparation for such a study on nicotinic receptors. As a continuation of our earlier study with acetylthiocholine on the same preparation, we now report on the characteristics of temperature-dependent binding of d-tubocurarine, a reversible antagonist. The O. Arunlakshana and H.O. Schild (1959, Br. J. Pharmacol. 14, 48) equation, as improved by D.R. Woud and R.B. Parker (1971, J. Pharmacol. Exp. Ther. 177, 13), was used to calculate the dissociation constant of d-tubocurarine at various temperatures (10-37 degrees C) from the parallel shift of the acetylcholine dose-response curve to the right by effective doses of d-tubocurarine. It was observed that the values of the dissociation constant increased with a decrease in temperature. Both the enthalpy (delta H degree) and entropy (delta S degree) changes as evaluated from the van't Hoff plot (In Kd vs. 1/T) were found to be positive and their relative value (delta H degree - T delta S degree) produced a negative free energy change which characterises the binding of d-tubocurarine as an entropy-controlled process. This finding is in agreement with the neurotoxin binding reported earlier. The present finding and earlier observations with acetylthiocholine reveal that agonist and antagonist binding to the nicotinic receptor may differ depending on the experimental conditions.

Animals↗
PubMed1996

Molecular cloning and expression of a recombinant Aspergillus fumigatus protein Asp f II with significant immunoglobulin E reactivity in allergic bronchopulmonary aspergillosis.

The cDNA of Aspergillus fumigatus encoding an allergen was cloned and expressed in Escherichia coli. The 987 bp long cDNA clone expressed a recombinant protein Asp f II of 34 kd. This protein exhibited binding to immunoglobulin E (IgE) in the serum samples from patients with allergic bronchopulmonary aspergillosis (ABPA). The patients with ABPA and central bronchiectasis demonstrated high levels of serum IgE antibodies, whereas patients with ABPA without central bronchiectasis, patients with asthma and Aspergillus skin test reactivity but no evidence of ABPA, and patients with aspergilloma showed only low levels of IgE antibody to Asp f II. In two-dimensional electrophoresis, a native antigen electroeluted from an A. fumigatus culture filtrate antigen preparation showed an isoelectric point and molecular weight similar to that of Asp f II. In a competitive enzyme-linked immunosorbent assay (ELISA), the IgE antibody reactivity of Asp f II with patient serum samples could be significantly inhibited by culture filtrate antigens of A. fumigatus. These results indicate that Asp f II has immunologic reactivities comparable to those of native A. fumigatus antigens. The recombinant Asp f II can be expressed in E. coli in large quantities and should prove useful as a standardized allergen for sensitive and specific immunodiagnosis of ABPA, especially in patients with central bronchiectasis.

Animals↗
PubMed1995

Thermodynamic studies with acetylthiocholine on nicotinic receptors of mammalian skeletal muscle in vitro.

The temperature dependency of binding of acetylthiocholine, a specific nicotinic agonist, to the nicotinic receptor of mammalian skeletal muscle was studied using isotonic contractions of the rat denervated diaphragm preparation in vitro. The dissociation constants at different temperatures (22-39 degrees) were determined by the Furchgott method using alpha-bungarotoxin as an irreversible antagonist. Both free energy of association (delta G zero = -22.93 kJ/mol at 37 degrees) and enthalpy of binding (delta H zero = -58.35 kJ/mol) calculated from Kd (dissociation constant) and slope of lnKd versus 1/T (van't Hoff plot) respectively were found to be negative. The negative entropy value (delta S zero = -0.113 kJ/mol/deg) obtained from the intercept of this van't Hoff plot differs from the large positive value obtained earlier employing radioligand binding studies of the nicotinic receptor of Electrophorus electricus.

Acetylthiocholine↗