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Biomedical subjects

A R Banerjee

Publications and source records attributed to A R Banerjee.

At least 19 recordsLinked to original sources
PubMed1998

Matrix metalloproteinase-2 and matrix metalloproteinase-9 in cholesteatoma and deep meatal skin.

A qualitative and quantitative study of the presence of Matrix metalloproteinase-2 (MMP-2) and Matrix metalloproteinase-9 (MMP-9) in cholesteatoma was performed. Ten cholesteatoma and four deep meatal skin specimens were analysed for gelatinase activity at molecular weights corresponding to MMP-2 and MMP-9 using Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS PAGE) Zymography. Gelatinase activity at 72 kDa and 92 kDa was investigated. Western blotting was employed using primary monoclonal antibodies to provide a qualitative assessment of MMP-2 and MMP-9. Non-parametric data analysis using the Mann-Whitney U test did not show a significant difference in expression of MMP-2 (P = 0.51) or MMP-9 (P = 0.14) between the two tissue types. Western blotting showed the presence of both MMP-2 and MMP-9 in the majority of specimens, both cholesteatoma and deep meatal skin.

Blotting, Western↗
PubMed1997

Kinetic mechanism of the hairpin ribozyme. Identification and characterization of two nonexchangeable conformations.

To investigate the relationship between RNA folding and ribozyme catalysis, we have carried out a detailed kinetic analysis of four structural derivatives of the hairpin ribozyme. Optimal and suboptimal (wild-type) substrate sequences were studied in conjunction with stabilization of helix 4, which supports formation of the catalytic core. Pre-steady-state and steady-state kinetic studies strongly support a model in which each of the ribozyme variants partitions between two major conformations leading to active and inactive ribozyme. substrate complexes. Reaction rates for cleavage, ligation, and substrate binding to both ribozyme conformations were determined. Ligation rates (3 min-1) were typically 15-fold greater than cleavage rates (0.2 min-1), demonstrating that the hairpin ribozyme is an efficient RNA ligase. On the other hand, substrate binding is very rapid (kon = 4 x 10(8) M-1 min-1), and the ribozyme. substrate complex is very stable (KD < 25 pM; koff < 0.01 min-1). Stabilization of helix 4 increases the proportion of RNA molecules folded into the active conformation, and enhances substrate association and ligation rates. These effects can be explained by stabilization of the catalytic core of the ribozyme. Rigorous consideration of conformational isomers and their intrinsic kinetic properties was necessary for development of a kinetic scheme for the ribozyme-catalyzed reaction.

Base Sequence↗
PubMed1997

Secondary structure model of the RNA recognized by the reverse transcriptase from the R2 retrotransposable element.

RNA transcripts corresponding to the 250-nt 3' untranslated region of the R2 non-LTR retrotransposable element are recognized by the R2 reverse transcriptase and are sufficient to serve as templates in the target DNA-primed reverse transcription (TPRT) reaction. The R2 protein encoded by the Bombyx mori R2 can recognize this region from both the B. mori and Drosophila melanogaster R2 elements even though these regions show little nucleotide sequence identity. A model for the RNA secondary structure of the 3' untranslated region of the D. melanogaster R2 retrotransposon was developed by sequence comparison of 10 species aided by free energy minimization. Chemical modification experiments are consistent with this prediction. A secondary structure model for the 3' untranslated region of R2 RNA from the R2 element from B. mori was obtained by a combination of chemical modification data and free energy minimization. These two secondary structure models, found independently, share several common sites. This study shows the utility of combining free energy minimization, sequence comparison, and chemical modification to model an RNA secondary structure.

Algorithms↗
PubMed1996

Cervical necrotizing fasciitis: a distinct clinicopathological entity?

Necrotizing fasciitis of the head and neck has previously been classified as a homogeneous group. We present two cases of necrotizing fasciitis confined to the neck and demonstrate with a review of the literature that cervical necrotizing fasciitis and craniofacial necrotizing fasciitis are two distinct clinicopathological conditions.

Adult↗
PubMed1996

Acetowhite staining in the detection of laryngeal disease.

The acetowhite staining reaction is widely used as a reliable adjunct to the diagnosis of malignant lesions in gynaecology, but its application in vocal cord lesions has not been assessed before. The use of the acetic acid staining reaction in selecting sites for sampling on the vocal cord is considered in this study. A 3% acetic acid solution was applied intraoperatively before biopsy to the larynx of eight patients who had either diffuse erythematous or polypoidal vocal cords. Attempts were made to correlate the degree of acetowhitening with the underlying histological findings. There was a very poor correlation between acetowhitening and the histological diagnosis, and very poor demarcation between stained and unstained areas. The application of acetic acid is not a useful adjunct to biopsy selection in the larynx.

Acetic Acid↗
PubMed1996

Is pre-operative patient assessment effective? A prospective trial of 100 patients.

The working patterns of clinical postgraduate trainees are being scrutinised in preparation for the implementation of new, structured and shortened postgraduate specialist training programmes. Current practice in the National Health Service dictates, in all branches of surgery, the evaluation of elective admissions undergoing procedures under general anaesthetic by a junior trainee (SHO or HO) who then arranges the appropriate preoperative investigations. This doctor acts as a "generalist' in that he is primarily concerned with the patient's general fitness for the operation as well as with the specific condition to be treated. The anaesthetist also evaluates the patient prior to the operation. In his case his sole concern is to whether or not the patient is fit for a general anaesthetic. This prospective study investigated the extent of duplication in preoperative elective patient assessment by both the otolaryngology trainee and the anaesthetist in order to answer the question: are both assessments necessary? The medical records of 100 consecutive adult elective admissions to the Leicester Royal Infirmary Otolaryngology Department which provides inpatient services to a catchment population of 900,000 were reviewed. The case histories obtained by clinicians blind to the study were classified as positive or negative for relevant features. The case histories obtained by the otolaryngology trainee and anaesthetist showed a level of disagreement which was 9 per cent greater than chance. It appears that there is a low level of duplication in preoperative elective otolaryngology patient assessment and both otolaryngology trainee and anaesthetic examination are of value.

Adolescent↗
PubMed1995

The time dependence of chemical modification reveals slow steps in the folding of a group I ribozyme.

L-21 ScaI ribozyme is a linear form of the self-splicing intron from the precursor of the Tetrahymena thermophila LSU intron. The time scales for tertiary folding of L-21 ScaI were investigated in two ways after bringing it from a partially denatured state at 60 degrees C and 1 mM Mg2+ to a renatured state of 15 degrees C and 10 mM Mg2+. First, formation of a catalytically active structure was monitored by measuring the kinetics of the reaction: p*CUCUA3 + G<==>p*CUCU + GA3. This reaction mimics the first step of splicing. After 1 min of folding time, the catalytic rate is roughly 10% of the rate attained after 8 h of folding. This indicates that much of the structure refolds quickly. Also, at least two time scales of folding are observed, separated by a lag time of about 30 min. To define the regions folding on various time scales, all the guanosines of L-21 ScaI were probed with kethoxal at 15 degrees C while folding was in progress. Based on folding time scales, the guanosines can be placed into at least four classes. These are guanosines that (1) are already protected at 60 degrees C in 1 mM Mg2+ or which fold immediately, (2) fold during the lag time, (3) continue to fold after 1 h, and (4) never fold. These results give insight into the folding pathway of a group I ribozyme at nucleotide resolution. This provides useful information on the regions whose foldings are important for catalytic function of the ribozyme. The method may also provide a general way to suggest regions of an RNA that may interact with each other to form tertiary structure.

Base Sequence↗
PubMed1995

Neck dissection.

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Carcinoma, Squamous Cell↗
PubMed1995

Free rib graft reconstruction of the mandible: a forgotten option?

Eleven patients underwent primary mandibular reconstruction following resection of a head and neck squamous cell carcinoma. Reconstruction consisted of a free rib graft and a pectoralis major myocutaneous flap. One rib graft failed and one graft, although successful, required removal during a wider resection for tumour recurrence. A further three patients have died since operation, two from tumour recurrence and one from unrelated medical causes. Six patients have undergone long-term follow-up of between 22 and 78 months with a mean of 51 months. They have oral continence, take a normal or semisolid diet, and have satisfactory cosmesis. We present the first long-term follow-up of a series of patients undergoing mandibular reconstruction with a free rib graft and pectoralis major myocutaneous flap.

Aged↗
PubMed1993

Thermal unfolding of a group I ribozyme: the low-temperature transition is primarily disruption of tertiary structure.

Little is known about the folding pathways of RNA. A particularly interesting RNA is L-21 Sca I, a linear form of the self-splicing intron from the precursor of the Tetrahymena thermophila large subunit (LSU) rRNA. Thermal unfolding of L-21 Sca I is studied by UV absorption and chemical mapping in 50 mM Na+ and 10 mM free Mg2+ at pH 7.5. UV melting experiments identify two major transitions with maxima at 65 and 73 degrees C. Chemical mapping at the beginning and middle of the first transition suggests it primarily involves disruption of tertiary structure. Phylogenetic comparisons suggest a potential tertiary interaction between loops L2.1 and L9.1a. Chemical mapping and melting experiments on a truncated form of the intron lacking P9.1a, L-21 Nhe I, are consistent with this hypothesis. The results indicate that increasing temperature disrupts tertiary interactions before disrupting secondary structure. This suggests tertiary interactions are weaker than secondary interactions in this case. These results support an important assumption for RNA structure prediction: that secondary structure dominates the free energy of folding.

Animals↗
PubMed1993

Ectopic salivary gland tissue in the palatine and lingual tonsil.

A case is reported of a child born with a developmental field defect of the first branchial arch in whom there was partial obstruction of the oropharynx by a horseshoe-shaped mass of what was thought to be tonsillar tissue. 'Tonsillectomy' was performed but histopathological examination of the excised specimens showed them to be almost entirely made up of salivary gland tissue.

Child, Preschool↗
PubMed1992

Haptoglobin subtypes in a Bengalee population sample.

HP1 subtyping has been performed on a Bengalee population sample of heterogeneous caste composition. The total sample size comes to n = 140 nonrelated adult individuals (68 males, 72 females). The following allele frequencies were observed: HP*1F = 0.0714, HP*1S = 0.1178, and HP*2 = 0.8107. It can be pointed out that the HP subtype distribution pattern found in the Bengalee sample follows in general the Oriental distribution pattern, though some differences are seen, especially concerning the HP*1F frequency.

Alleles↗
PubMed1985

Pygopagus twins.

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Adult↗