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Biomedical subjects

A K Bhattacharyya

Publications and source records attributed to A K Bhattacharyya.

At least 19 recordsLinked to original sources
PubMed2006

Water precautions and ear surgery: evidence and practice in the UK.

BACKGROUND: Patients are traditionally advised to refrain from exposing their ears to water after most otological procedures. However, recent evidence suggests that water does not adversely affect the outcome for children with tympanostomy tubes. The evidence behind the potential harmful effects of water on the outcome of other otological procedures is scarce. OBJECTIVE: The study was done to determine the current practice of otolaryngology consultants in the UK on the advice given to patients regarding swimming, diving and bathing in soapy water after myringotomy and tympanostomy tube insertion, mastoidectomy and myringoplasty. METHOD: Questionnaire based survey mailed to 382 members (consultants only) of the British Association of Otolaryngologists--Head & Neck Surgeons in the UK. RESULTS: A total of 195 responses were received (reply rate 51 per cent). In all, 95.6 per cent of the respondents allowed their patients to swim after insertion of tympanostomy tubes, with 32.9 per cent insisting on the use of earplugs until extrusion of the tympanostomy tubes. However, 61.6 per cent of the respondents restricted diving in these patients. In comparison, the respondents were more conservative with water precautions following myringoplasty and mastoidectomy. More than half the respondents recommended earplugs for bathing after all three operations. CONCLUSION: This study reveals current national practice among UK otolaryngologists. There is no general consensus in post-operative advice following otolaryngological procedures, indicating a need for national guidelines.

Baths↗
PubMed2006

A systematic review of the role of proton pump inhibitors for symptoms of laryngopharyngeal reflux.

. Proton pump inhibitors are currently used widely for the treatment of laryngopharyngeal reflux. . This systematic review assessed the efficacy of proton pump inhibitors in the treatment of symptoms of laryngopharyngeal reflux. . Outcome measures used to assess efficacy of proton pump inhibitors included endoscopic laryngeal signs and pH recordings. .Only two small randomized-controlled trials included patients with objective evidence of reflux in the 24-h ambulatory oesophageal pH monitoring. . Pooled analysis of these two randomized-controlled trials failed to show any effect in favour of treatment with proton pump inhibitors. .Further randomized-controlled trials are required to ascertain the role of proton pump inhibitors in the treatment of laryngopharyngeal reflux.

Anti-Ulcer Agents↗
PubMed2005

Phase III trial of ursodeoxycholic acid to prevent colorectal adenoma recurrence.

BACKGROUND: Ursodeoxycholic acid (UDCA) treatment is associated with a reduced incidence of colonic neoplasia in preclinical models and in patients with conditions associated with an increased risk for colon cancer. We conducted a phase III, double-blind placebo-controlled trial of UDCA to evaluate its ability to prevent colorectal adenoma recurrence. METHODS: We randomly assigned 1285 individuals who had undergone removal of a colorectal adenoma within the past 6 months to daily treatment with UDCA (8-10 mg/kg of body weight; 661 participants) or with placebo (624 participants) for 3 years or until follow-up colonoscopy. Recurrence rates (number of recurrent adenomas per unit time) were compared by use of a Huber-White variance estimator. Proportions of participants with one or more recurrent adenomas were compared with a Pearson chi-square statistic; adjusted odds ratios (ORs) were obtained by logistic regression. All statistical tests were two-sided. RESULTS: We observed a non-statistically significant 12% reduction in the adenoma recurrence rate associated with UDCA treatment, compared with placebo treatment. However, UDCA treatment was associated with a statistically significant reduction (P = .03) in the recurrence of adenomas with high-grade dysplasia (adjusted OR = 0.61, 95% confidence interval = 0.39 to 0.96). We observed no statistically significant differences between UDCA and placebo groups in recurrence with regard to adenoma size, villous histology, or location. CONCLUSIONS: UDCA treatment was associated with a non-statistically significant reduction in total colorectal adenoma recurrence but with a statistically significant 39% reduction in recurrence of adenomas with high-grade dysplasia. Because severely dysplastic lesions have a high risk of progression to invasive colorectal carcinoma, this finding indicates that future chemoprevention trials of UDCA in individuals with such lesions should be considered.

Adenoma↗
PubMed2004

Studies on the membrane integrity of human sperm treated with a new injectable male contraceptive.

BACKGROUND: The aim of this study was to evaluate the integrity of sperm surface characteristics in the presence of a new male contraceptive, RISUG [1 mg styrene maleic anhydride (SMA)/100 microl dimethylsulphoxide (DMSO) in 1 ml sperm solution]. METHODS: Progressively motile human sperm were treated in vitro with RISUG. The cells were analysed for the release of 5'-nucleotidase (5'-NT) (a plasma membrane marker) using 3 mmol/l 5'-AMP and 3 mmol/l beta-glycerophosphate as substrates. Hyaluronidase (an acrosomal membrane marker) was analysed using hyaluronic acid as a substrate. The contents of free and total acrosin, and % proacrosin (all acrosome markers) were assayed using 0.5 mmol/l alpha-N-benzoyl-L-arginine ethylester (BAEE). RESULTS: RISUG caused almost complete disintegration of the plasma membrane leading to significant (P < 0.0001) release of 5'-NT into the surrounding media. Complete dissolution of the acrosome with concomitant vesiculation of the membrane system, as judged from the loss of hyaluronidase, was observed. Total acrosin content in the sperm was also reduced to almost 10%, and proacrosin dropped to 13.2% in the presence of RISUG in comparison to 90.2% in control (P < 0.0001), indicating dispersion of acrosomal contents. CONCLUSION: Under in vitro conditions, RISUG, at a concentration of 1 mg SMA dissolved in 100 microl of DMSO, caused significant damage to the acrosome and its contents, indicating loss of functional ability of sperm.

Acrosin↗
PubMed2004

Endoscopic stapling of pharyngeal pouch.

The relatively new technique of endoscopic stapling in the surgical management of pharyngeal pouch has gained widespread popularity over the last few years. The technique seems to be the procedure of choice as it is easier and quicker to perform and has a lower morbidity compared with open techniques. We present here an overview of the current evidence provided by a literature search performed by Ovid MEDLINE on literature published between January 1993 and May 2003 on endoscopic stapling of pharyngeal pouch. Several case series have been reported on various aspects of the surgery. The modifications in technique, peri-operative care, success rate, complications and recurrence are summarized, based on observational analytical case series. There were no randomized controlled trials comparing this approach to any other endoscopic or open surgical techniques for pharyngeal pouch.

Esophagoscopy↗
PubMed2003

Primary orbital lymphoma.

Primary orbital lymphoma is a rare condition involving primarily the lacrimal glands. We present the second Indian case of right-sided primary orbital lymphoma in an elderly male who presented with the typical features and showed a good response to chemotherapy.

Diagnosis, Differential↗
PubMed2001

Site-directed mutagenesis studies of rat steroid 5alpha-reductase (isozyme-1): mutation of residues in the cofactor binding and C-terminal regions.

We have investigated the roles of highly conserved glycine (G175, G185), negatively charged (E188, D165) and histidine residues (H233, H237) in rat steroid 5alpha-reductase (isozyme-1), on NADPH, testosterone (T) binding and enzyme activity. The mutations G175R and G175S result in a two- to threefold increase in K(m)(NADPH) and an approximately fourfold decrease in the V(max) with no change in K(m)(T). The mutation G185W resulted in a fivefold decrease in K(m)(NADPH) and an eightfold decrease in V(max), with no change in K(m)(T), whereas the mutations E188Q and D165N both resulted in inactive enzyme. Steady-state kinetic measurements showed that the mutation H233R resulted in an approximately 40-fold decrease in V(max), an approximately 20-fold increase in K(m)(T) and no alteration in K(m)(NADPH), whereas the mutation H237R resulted in virtually inactive enzyme. The results suggest that the conserved glycines are not essential for cofactor binding and activity, and that the negatively charged residues may contribute to enzyme stability, whereas the C-terminal histidines appear to be involved in substrate binding and catalytic activity.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Adenoma characteristics as risk factors for recurrence of advanced adenomas.

BACKGROUND AND AIMS: The link between adenoma characteristics at baseline colonoscopy and adenoma recurrence is poorly understood. We assessed whether the number, size, location, or histology of resected adenomas was related to the probability of recurrence of advanced lesions. METHODS: Analyses were based on 1287 men and women in the wheat bran fiber (WBF) study, a randomized, double-blind trial of WBF as a means of decreasing the probability of adenoma recurrence over a period of 3 years. Multiple logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Recurrence of advanced adenomas (>1 cm or tubulovillous/villous histology) was higher among individuals with adenomas >1 cm compared with those with adenomas <0.5 cm (OR, 2.69; 95% CI, 1.34-5.42) and among those with proximal than those with distal adenomas (OR, 1.65; 95% CI, 1.02-2.67). No association was observed for adenoma number or histology. A shift in location from the distal colon and rectum at baseline (54.6%) to more proximal recurrent adenomas (45.2%), including advanced lesions (42.8%), was observed. CONCLUSIONS: Large or proximally located adenomas are important indicators of recurrence of advanced lesions. Because most recurrences were detected in the proximal colon, careful surveillance of this area is warranted.

Adenoma↗
PubMed2001

Ki-ras proto-oncogene mutations in sporadic colorectal adenomas: relationship to histologic and clinical characteristics.

BACKGROUND & AIMS: [corrected] The goal of this study was to examine the relationship between Ki-ras mutations in colorectal adenomas and characteristics of both the subject (age, gender, and family/personal history of colonic neoplasia) and the adenoma (multiplicity, size, location, and histologic features). METHODS: Ki-ras mutations were detected by direct sequencing in 738 adenomatous polyps removed at baseline from 639 participants in a nutritional trial of adenoma recurrence. RESULTS: Ki-ras mutations were detected in 17.2% of the adenomas. Ki-ras mutations were unrelated to gender, family, or personal history of colonic neoplasia, location within the colorectum, or adenoma multiplicity, but were more common in older subjects (P = 0.01 for trend), in larger adenomas (P < 0.0001 for trend), in adenomas with villous histology (odds ratio [OR], 3.2; 95% confidence interval [CI], 2.1-4.9 vs. tubular), and in adenomas with high-grade dysplasia (32.0% vs. 13.6%; OR, 3.0; 95% CI, 1.9-4.6 vs. low-grade dysplasia). Multivariate analysis showed Ki-ras mutations to be independently associated with subject age (P = 0.01 for trend), tubulovillous/villous histology (OR, 2.3; 95% CI, 1.5-3.7), and high-grade dysplasia (OR, 1.9; 95% CI, 1.2-3.1). Adenoma size was not independently related to Ki-ras mutation. CONCLUSIONS: Ki-ras mutations are associated with the histologic features of adenoma progression (villous histology and high-grade dysplasia) rather than with adenoma growth.

Adenoma↗
PubMed2001

Telepathology overview: from concept to implementation.

Telepathology is the practice of pathology at a distance by using video imaging and telecommunications. Significant progress has been made in telepathology. To date, 12 classes of telepathology systems have been engineered. Rapid and ultrarapid virtual slide processors may further expand the range of telepathology applications. Next-generation digital imaging light microscopes, such as miniaturized microscope arrays (MMA), may make virtual slide processing a routine laboratory tool. Diagnostic accuracy of telepathology is comparable with that of conventional light microscopy for most diagnoses. Current telepathology applications include intraoperative frozen sections services, routine surgical pathology services, second opinions, and subspecialty consultations. Three telepathology practice models are discussed: the subspecialty practice (SSP) model; the case triage practice (CTP) model; and the virtual group practice (VGP) model. Human factors influence performance with telepathology. Experience with 500 telepathology cases from multiple organs significantly reduces the video viewing time per case (P < .01). Many technology innovations can be represented as S-curves. After long incubation periods, technology use and/or efficiency may accelerate. Telepathology appears to be following an S-curve for a technical innovation.

Diffusion of Innovation↗
PubMed2000

The effects of dietary selenomethionine on polyamines and azoxymethane-induced aberrant crypts.

We evaluated the effects of dietary selenomethionine supplementation on colonic polyamine levels and the ability of L-selenomethionine supplementation to modulate the carcinogenic activity of azoxymethane (AOM) in the rat colon. Four-week-old male F344 rats were treated with 15 mg/kg body weight of AOM once a week for 2 weeks. Dietary selenomethionine at a concentration of either 1 or 2 ppm was administered in AIN-76A rodent diet to AOM-treated animals for 16 weeks. Aberrant crypt foci (ACF), precursor lesions of colon cancer, were investigated after the 16 week treatment course. Selenomethionine given in the diet at 2 ppm markedly reduced the number of aberrant crypt foci. The multiplicity of ACFs (i.e. the number of aberrant crypts/focus) and the percentage of microadenomas were also affected by selenomethionine in a dose dependent manner. However, evaluation of the colonic tissue polyamine levels between control and treated groups showed no significant difference. These results demonstrate that selenomethionine can modulate the development of AOM-induced premalignant lesions through a polyamine-independent mechanism.

Alanine Transaminase↗
PubMed1999

Analysis of the steroid binding domain of rat steroid 5alpha-reductase (isozyme-1): the steroid D-ring binding domain of 5alpha-reductase.

We have previously shown that the photoactive 4-azasteroid, [1,2 3H]N-4(benzylbenzoyl)-3-oxo-4-aza-4-methyl-5alpha-androst an-17beta-carboxamide is an effective probe of rat steroid 5alpha-reductase (isozyme-1) (5alphaR-1). In the current investigation, PEG-fractionated (6.5%) detergent-solubilized preparations containing 5alphaR-1 activity were ultraviolet (UV)-photolyzed with [3H]-4MABP and subsequently purified by 8.75% preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The fractions corresponding to the radioactive peak following the dye front were analyzed by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and showed the presence of a single, labeled, 26 KDa protein band, the apparent molecular weight of 5alphaR-1. TCA precipitation of the labeled fractions, followed by long-term digestion of the TCA pellet with chymotrypsin and high-performance liquid chromatography analysis, indicated that the majority of the radioactivity eluted with a peak retention time of 55-56 min. Rechromatography of this fraction using a modified gradient (elution 54-55 min), followed by sequence analysis, yielded a single N-terminal tetrapeptide with the sequence, -L-E-G-F-, corresponding to residues 15-18 of the 5alphaR-1 sequence. Site-directed mutagenesis studies indicated that mutant F18L showed an approximately 12-fold increase in the Km for testosterone, whereas the Km for reduced nicotinomide adenine dinucleotide phosphate remained virtually unaltered.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1999

Site-directed mutagenesis studies of the NADPH-binding domain of rat steroid 5alpha-reductase (isozyme-1) I: analysis of aromatic and hydroxylated amino acid residues.

Previous studies have shown that the reduced nicotinamide adenine dinucleotide phosphate (NADPH)- binding domain of rat liver microsomal steroid 5alpha-reductase isozyme-1 (r5alphaR-1) is in a highly conserved region of the polypeptide sequence (residues 160-190). In this study, we investigated, by site-directed mutagenesis, the role of hydroxylated and aromatic amino acids within the NADPH-binding domain. The r5alphaR-1 cDNA was cloned into a pCMV vector, and the double strand site-directed mutagenesis method was used to create mutants Y179F, Y179S, Y189F, Y189S, S164A, S164T, and Y187F, which were subsequently expressed in COS-1 cells. Kinetic studies of the expressed enzymes showed that the mutation Y179F resulted in an approximately 40-fold increase in the Km for NADPH versus wild-type, with only a 2-fold increase in the Km for testosterone. The mutants Y189F and S164A showed smaller increases (4 and 6-fold) in Kms for NADPH and no significant change in the Km for testosterone, whereas Y189S had kinetic properties similar to the wild-type r5alphaR-1. Mutants Y179S and S164T both resulted in inactive enzymes, whereas F187Y showed an approximately 5-fold decrease in Km for NADPH and a significant increase (approximately 18-fold) in the Km for testosterone. The results suggest that the -OH functionality of Y179 is involved in cofactor binding, but is not essential for the activity of the enzyme, whereas the -OH functionalities of Y189 and S164 play lesser roles in cofactor binding to r5alphaR-1 and may not be required for enzyme activity. On the other hand, the residue F187 may be important for the binding of both NADPH and testosterone.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1998

Telemicrobiology: feasibility study.

BACKGROUND: Rural hospitals generally lack staffing with infectious disease specialists or pathologists. Without on-site pathologists, the range of microbiology services offered by clinical laboratories may be limited as well. OBJECTIVE: To study the feasibility of using static-image telepathology to evaluate Gram stains of microbiologic preparations. MATERIALS AND METHODS: In this retrospective feasibility study, three pathologists evaluated Gram stains of slides from 50 cases by two viewing modalities: static-image telepathology and conventional light microscopy. Digital video images of slides were captured at two magnifications (using 40x and 100x objective lenses) at 1024 x 768 x 24-bit color and transmitted over standard telephone lines at 14,400 kbps. Pathology reports and culture results served as "truth diagnoses." Categories of interpretations were correct, minor discrepancy, or major discrepancy with regard to the implications for patient care. RESULTS: The diagnostic accuracy of video image readings and conventional light microscopy readings were nearly identical, with no statistically significant differences in the performances of specialty and nonspecialty pathologists (P > 0.05). The mean accuracies of readings of the video images and light microscopy images were 95.3% and 95.4%, respectively. Taking into account the time required by a referring pathologist to capture video digital images, telemicrobiology was somewhat less efficient than conventional light microscopy. CONCLUSIONS: Pathologists can accurately evaluate digital video images of preselected fields on Gram-stained slides. In clinical practice, however, a limiting factor may be the availability of local personnel qualified to select the microscopic fields for evaluation by telepathologists. The adequacy of the video images suggests that telepathology may also be used for remote supervision of quality assurance programs in microbiology laboratories, as well as for remote proficiency training of laboratory personnel.

Arizona↗
PubMed1997

Expression of rat steroid 5 alpha-reductase (isozyme-1) in Spodoptera frugiperda, SF21, insect cells: expression of rat steroid 5 alpha-reductase.

The enzyme steroid 5 alpha-reductase (5 alpha R) catalyzes the reduction of testosterone (T) to 5 alpha-dihydrotestosterone (DHT). In this study, the baculovirus expression system was used to overexpress rat 5 alpha R type I isozyme (r5 alpha R 1). The full length of r5 alpha R1 cDNA was inserted into the Autographa californica nuclear polyhedrosis virus (Ac-MNPV) genome and expressed in Spodoptera frugiperda, Sf 21, insect cells. The expressed recombinant r5 alpha-R1 showed maximal enzymatic activity when the infected cells were harvested on day 3 of post-transfection. The K(m) values for NADPH and T were 17 microM and 2.7 microM, respectively. Inhibition of the recombinant r5 alpha R1 by N,N diethyl-4-aza-4-methyl-3-oxo-5 alpha-androstane-17 beta-carboxamide (4MA) was competitive with respect to the substrate (T), and a Ki of 3 nM was obtained. The enzyme was located primarily in the nuclear fraction, and the maximum velocity for the recombinant r5 alpha R1 in this fraction was 60 nmoles DHT/min/mg. Immunoblot analysis indicated a single immunoreactive band at 26 kDa, which corresponds to the molecular weight of r5 alpha R1. Photoaffinity labeling by [2'-32P]-2-azido-NAD P+ ([2'-32P]2N3-NAD P+) and [1,2(3)H] N-(benzylbenzoyl)-3-oxo-4-aza-4-methyl-5 alpha androstane-17 beta-carboxamide ([3H]-4MABP) also showed a labeled protein band at 26 kDa.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗