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Biomedical subjects

K Chowdhury

Publications and source records attributed to K Chowdhury.

88 records · Page 5Linked to original sources
PubMed1976

Random cleavage of superhelical SV 40 DNA S1 nuclease.

SV40 DNA FO I is randomly cleaved by S1 nuclease both at moderate (50 mM) and higher salt concentrations (250 mM NaC1). Full length linear S1 cleavage products of SV40 DNA when digested with various restriction endonucleases revealed fragments that were electrophoretically indistinguishable from the products found after digestion of superhelical SV40 DNA FO I with the corresponding enzyme. Concordingly, when the linear S1 generated duplexes were melted and renatured, circular duplexes were formed in addition to complex larger structures. This indicated that cleavage must have occurred at different sites. The double-strand-cleaving activity present in S1 nuclease preparations requires circular DNA as a substrate, as linear SV40 DNA is not cleaved. With regard to these properties S1 nuclease resembles some of the complex type I restriction nucleases from Escherichia coli which also cleave SV40 DNA only once, and, completely at random.

Centrifugation, Density Gradient↗
PubMedDate not supplied

Resorbable plate fixation in pediatric craniofacial surgery: long-term outcome.

OBJECTIVE: To determine the long-term efficacy of resorbable plate fixation in pediatric patients undergoing craniofacial surgery for congenital anomalies, traumatic deformities, or skull base tumors. DESIGN: Retrospective case review. MATERIALS AND METHODS: Medical records of 57 consecutive cases using resorbable plates and screws for craniofacial fixation in patients younger than 18 years were analyzed. MAIN OUTCOME MEASURES: The status of bone healing postoperatively (anatomical union, malunion, delayed union, or nonunion) and any complications or adverse effects (hardware visibility or palpability, plate extrusion, or infection) were noted. RESULTS: In midfacial and upper face procedures (54 patients) anatomical union and uncomplicated bone healing occurred in 52 (96%) of the patients. In this same group, complications (plate extrusion) occurred in 2 patients (3.7%) and were resolved using conservative treatment without untoward sequelae. These outcomes are comparable to results using metal osteosynthesis in similar situations. Costs of resorbable hardware are similar to existing metal fixation systems. CONCLUSIONS: Our data support the use of bioresorbable plate fixation in pediatric craniofacial surgery as a means of avoiding the potential and well-documented problems with rigid metal fixation. Indications include fractures and segmental repositioning in low-stress non-load-bearing areas of the middle and upper craniofacial skeleton. Although there is an initial learning curve in using this technology, we believe the benefits are well worth the effort and represent a major advance in pediatric craniofacial surgery.

Absorbable Implants↗
PubMedDate not supplied

Spontaneous and nonspontaneous internal jugular vein thrombosis.

Nonspontaneous internal jugular vein thrombosis (IJVT) is an uncommon condition historically associated with deep neck infections during the pre-antibiotic era. Today, trauma to the internal jugular vein from catheterization and repeated intravenous injections by drug users are the leading causes of thrombosis, with direct extension of tumor being a rare cause. Spontaneous IJVT occurs when there are no apparent predisposing causes, although many of these patients may harbor an occult malignant neoplasm. Therefore, careful investigation and follow-up are imperative in these patients. The diagnosis of IJVT is readily confirmed by contrast-enhanced computed tomography or magnetic resonance imaging. Management of IJVT involves anticoagulation, antibiotics, and with few indications for surgical intervention.

Aged↗
PubMedDate not supplied

Structural analysis of murine genes containing homoeo box sequences and their expression in embryonal carcinoma cells.

The presence of homoeo box sequences in the genomes of vertebrates has suggested that these metazoans possess the equivalent of the homoeotic genes that have a key role in regulating the development of the fruitfly Drosophila melanogaster. We report here that a novel murine homoeo box-containing gene is expressed in embryonal carcinoma stem cells. Transcripts of the sequences that flank the homoeo box of this gene are found in these cells before and after induced differentiation, whereas a specific transcript that seems to contain the homoeo sequence is only present after differentiation.

Animals↗
PubMedDate not supplied

Enteropathogenicity of plesiomonas shigelloides by oral inoculation in adult conditioned rabbits.

To study presumptive diarrhoeagenic and invasive properties of Plesiomonas shigelloides, adult conditioned rabbits (n = 75) were fed 10(10) CFU of 3 isolates (2 from diarrhoea patients and one from river water) of the organism, and one isolate of Shigella sonnei (from a dysentery patient as positive control) or brain-heart infusion broth (as negative control). Each rabbit received in succession i.v. cimetidine (50 mg/kg body weight), two 15 ml oral doses of 5% NaHCO3 at 15 and 30 minutes respectively, prompt bacterial or sham inoculum followed 30 minutes by 2 ml of i.p. tincture of opium. Rabbits fed with P. shigelloides did not die or develop diarrhoea, but in a majority of them, histopathological examinations of the intestine revealed mild acute inflammation of the mucosa, mainly in the ileum. There was no serum antibody response by indirect haemagglutination against the lipopolysaccharide of the homologous strains of P. shigelloides. The culture filtrates of the organism also did not show any cytotoxic morphological changes on CHO and Y1 adrenal cell cultures. By contrast, rabbits fed with S. sonnei developed clinical diarrhoea, small to widespread severe acute inflammation of the gut mucosa, and all died on day 7. It may be concluded that P. shigelloides are able to provoke a mild inflammatory lesions of the gut mucosa in this rabbit model; but there is little prospect of using this model to assess easily the virulence of the organism.

Animals↗