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Biomedical subjects

A Mitra

Publications and source records attributed to A Mitra.

At least 73 records · Page 4Linked to original sources
PubMed1995

Isolated avulsion of the flexor digitorum superficialis tendon.

Isolated, closed avulsion of the flexor digitorum superficialis tendon at its insertion is thought to be a rare diagnostic entity, with only six cases reported in the literature. However, we have diagnosed and treated 11 such cases, each presenting with a tender palmar mass and loss of active flexor digitorum superficialis function. Some patients had proximal interphalangeal joint contractures. Upon exploration, the retracted superficialis tendon was found to ensnare the profundus tendon at the level of the A1 pulley. Following tenolysis, flexor digitorum superficialis tendon excision, and in selected patients capsulotomies, each patient achieved good functional capacity.

Adult↗
PubMed1995

Structure and function of kidney water channels.

There is now firm evidence that water transporting proteins are expressed in renal and extrarenal tissues. In the kidney, proximal-type (CHIP28) and collecting duct (WCH-CD) water channels have been identified. We have cloned three kidney cDNAs with homology to the water channel (aquaporin) family, including a mercurial-insensitive water channel (MIWC), and a glycerol-transporting protein (GLIP) in collecting duct basolateral membrane. To elucidate water transporting mechanisms, a series of molecular and spectroscopic studies were carried out on purified CHIP28 protein and expressed chimeric and mutated CHIP28 cDNAs. The results indicate that CHIP28 transports water selectively, that CHIP28 monomers are assembled in membranes as tetramers, but that individual monomers function independently. Monomers contain multiple membrane-spanning helical domains. Based on these data and recent electron crystallography results, a model for water transport is proposed in which water moves through narrow pores located within individual CHIP28 monomers.

Amino Acid Sequence↗
PubMed1995

Peroneal nerve entrapment in athletes.

Peroneal nerve entrapment is one of the less common causes of exercise-induced leg pain in competitive athletes. This type of lower extremity peripheral nerve dysfunction is usually associated with activities that subject the nerve to constant compression or repetitive trauma. Herein, we present our experience with 12 competitive athletes treated for peroneal nerve entrapment. Diagnostic electromyography results, intraoperative findings, and the results of cadaveric dissections are discussed.

Athletic Injuries↗
PubMed1995

On-site adequacy assessments for image-directed fine needle aspirations: a study of 341 cases.

On-site adequacy assessments (OSAA) are reported to decrease the unsatisfactory and nondiagnostic rates of fine needle aspirations (FNAs). These have been routine in many institutions but were only recently introduced to our large teaching hospital. The results of FNAs performed in diagnostic radiology between January to December 1992 were compared to aspirations done by the same clinical staff during the first year (1993) after the addition of an on-site adequacy assessment service. In the year prior to OSAA, 154 FNAs were performed in diagnostic radiology and the material obtained was processed by a cytotechnologist. Of these, 89 (58%) cases were positive for malignant cells. Approximately half of these cases had confirmatory tissue biopsies processed in the surgical pathology department of our institution. The remaining 65 (42%) of cytology specimens were determined to be negative or nondiagnostic for malignancy. These canes either had no tissue follow-up or the tissue obtained was nondiagnostic. Before beginning OSAA, nine cases (6%) were interpreted as negative for malignancy, but subsequent tissue biopsies were malignant. There were no false positives during this time. Diagnostic sensitivity was 86% before OSAA. One hundred seventy-seven image directed FNAs were performed in the first year following the establishment of OSAA. Of these, 102 (58%) cases were interpreted as positive for malignant cells. About half of these patients went on to have confirmative tissue biopsies. Fifty-six (32%) cases were interpreted as negative for malignancy or nondiagnostic on FNA and follow-up tissue biopsies were also either negative or nondiagnostic. The false negative rate was 1% after OSAA and there were no false positives during this period. Diagnostic sensitivity was 98% after OSAA. In addition, the average overall number of passes per patient have decreased from 2.4 before OSAA to 1.6 after OSAA.

Biopsy, Needle↗
PubMed1994

A Chlorella virus gene promoter functions as a strong promoter both in plants and bacteria.

An upstream region from an algal virus methyltransferase gene was tested for promoter function in transgenic plants, electroporated monocot protoplasts and bacteria. Fusion of the 851 bp upstream region to a reporter gene significantly enhanced the reporter gene expression in transgenic Arabidopsis and potato plants and in electroporated maize and Sorghum cells relative to the cauliflower mosaic virus 35S promoter. The promoter was also functional in several Escherichia coli strains and in three species of phytopathogenic bacteria, Erwinia, Pseudomonas, and Xanthomonas. These findings indicate that the upstream region is a strong promoter uniquely functional in both eukaryotes and prokaryotes and capable of using both eukaryotic RNA polymerase II and bacterial RNA polymerases.

Arabidopsis↗
PubMed1994

Superoxide generation by lipoxygenase in the presence of NADH and NADPH.

The ability of soybean lipoxygenase to mediate NAD(P)H oxidation and concomitant superoxide generation in the presence of linoleic acid was examined. At optimum pH of 8.3, lipoxygenase oxidized both NADH and NADPH in the presence of 700 microM linoleic acid. The oxidation of NAD(P)H was biphasic. The initial rates of NADH and NADPH oxidation were 130 and 140 nmoles/min/nmole of enzyme respectively and the corresponding final rates were 344 and 350 nmoles/min/nmole of enzyme. The apparent Km values calculated for NADH and NADPH oxidation were 13 microM and 117 microM respectively. NAD(P)H oxidation was accompanied by the reduction of either ferricytochrome c or nitroblue tetrazolium (NBT) which can be abolished (approx. 85%) by superoxide dismutase (SOD) suggesting the generation of superoxide anion radicals. Under optimal conditions, the rates of superoxide generation, measured as the SOD-inhibitable reduction of ferricytochrome c, were 325 and 235 nmoles/min/nmole of enzyme for NADH and NADPH respectively. Under identical experimental conditions, the SOD-inhibitable NBT reduction rates were 308 and 210 nmoles/min/nmole of enzyme for NADH and NADPH respectively. Both NADH and NADPH could be regenerated after oxidation using the appropriate dehydrogenases. These results strongly suggest that lipoxygenase not only generates lipid hydroperoxides but can also generate superoxide via oxidation of pyridine nucleotides and may, therefore, significantly contribute to oxidative stress in cells.

Alcohol Dehydrogenase↗
PubMed1994

Ectopic expression of a viral adenine methyltransferase gene in tobacco.

Plant genomes contain both methylated adenine and cytosine residues although the roles of these methylations are not well understood. A chlorella virus adenine methyltransferase gene under the control of cauliflower mosaic virus 35S promoter in a binary plant transformation vector was expressed both in transgenic tobacco plants and transformed tobacco calli. The transgenic plants as well as transformed calli produced functional adenine methyltransferase enzyme, but the level of expression was higher in tobacco calli. A transgenic tobacco cell line that expressed the methyltransferase enzyme and carried an Arabidopsis cab3 gene containing a single target site for the adenine methyltransferase enzyme showed that the adenine residue was not methylated. HPLC analysis of genomic DNA from transgenic calli also showed no detectable levels of methylated adenine residues.

Base Sequence↗
PubMed1994

The C-terminal region of carboxypeptidase E is involved in membrane binding and intracellular routing in AtT-20 cells.

Carboxypeptidase E (CPE), a neuropeptide processing enzyme, is present in neuroendocrine tissues in soluble and membrane-associated forms. The membrane-associated forms do not contain a conventional transmembrane-spanning domain; instead, the C-terminal region of CPE has been proposed to form an amphiphilic helix which binds to the membrane. To test this, and to investigate the possible contribution of this C-terminal sequence to the intracellular sorting of CPE into the regulated pathway, the C-terminal region of CPE was attached to albumin and the recombinant proteins expressed in AtT-20 cells. Albumin itself showed little association with membranes under the conditions examined. A construct containing albumin with only 9 residues of CPE, corresponding to a highly charged region immediately preceding the potential amphiphilic helix region, showed generally similar membrane binding and secretion rates as albumin alone. When the C-terminal 51 amino acids of CPE were attached to the C terminus of albumin and the recombinant protein detected with an antisera raised against the C terminus of CPE, virtually all of the protein was membrane-associated. This finding suggests that the C-terminal region of CPE functions as a membrane anchor. The secretion of albumin with the C-terminal region of CPE was stimulated by a phorbol ester and by forskolin, although the magnitude of the stimulation was smaller than the effect of these compounds on the secretion of CPE. These results imply that the C-terminal region of CPE contains the membrane anchor and contributes to the sorting of this protein into the regulated pathway.

Amino Acid Sequence↗
PubMed1994

The Chlorella virus adenine methyltransferase gene promoter is a strong promoter in plants.

An upstream region isolated from a eukaryotic algal virus adenine methyltransferase gene was tested for promoter function in plants. Fusion of this region to the chloramphenicol acetyltransferase reporter gene resulted in significantly higher expression than fusion with the cauliflower mosaic virus 35S promoter. Strong levels of expression were also found in electroporated monocot plant cells. The promoter activity in transgenic tobacco plants showed tissue-specific expression. Leaves had the highest expression followed by stems and flowers. The promoter activity was not detected in root tissue. Environmental cues, such as light, and the phytohormones auxin and cytokinines had no effect on the promoter's expression. This promoter might be utilized to achieve high levels of expression of introduced genes in higher plants.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1994

Typing of Shigella dysenteriae strains of different serogroups by lectins.

Ten different serogroups of Shigella dysenteriae were typed with the aid of lectins of known sugar specificity resulting from their interactions with the carbohydrates on lipopolysaccharides in the outer membrane of bacteria as evidenced by the agglutination-inhibition assay with simple carbohydrates. Lipopolysaccharides of two serogroups of Shigella were precipitated with different lectins and the results were corroborated by those derived from the agglutination assay suggesting that Shigella dysenteriae can be characterized on the species level with the aid of lectins.

Agglutination↗
PubMed1994

Dupuytren's contracture in the black population: a review.

There is general agreement that Dupuytren's contracture is a genetic disorder that occurs predominantly in white men of Northern European ancestry. It appears rarely in the purely black population. We present our experience from Temple University of 8 black patients with Dupuytren's contracture. We also present a review of the world literature dealing with the black population and Dupuytren's disease. A total of 23 patients are reviewed, including our group. They all fall into the category of no Caucasian admixture and negative family history of Dupuytren's contracture. Every patient reviewed has at least 1 hand involved. History and presentation of disease, as well as epidemiological associations (e.g., age distribution, diabetes, and epilepsy), in our review are similar to that seen in the Caucasian population. The diathesis or predisposition for Dupuytren's contracture appears to be less extensive in our series of 8 black patients. History taking, with regard to occupation and possible traumatic etiology, remains a very useful tool.

Aged↗
PubMed1994

Expression of a human lactoferrin cDNA in tobacco cells produces antibacterial protein(s).

A suspension tobacco (Nicotiana tabacum L.) cell line was transformed to express human lactoferrin, an iron-binding glycoprotein. The transgenic calli produced a protein that was significantly smaller than the full-length lactoferrin protein. Total protein extracts made from transgenic tobacco callus exhibited much higher antibacterial activity than commercially available purified lactoferrin as determined by the decrease of colony-forming units when tested with four phytopathogenic species of bacteria. Introduction of the lactoferrin gene in crop plants may provide resistance against phytopathogenic bacteria.

Anti-Bacterial Agents↗
PubMed1994

Clostridium difficile in antibiotic associated pediatric diarrhea.

A case control study was carried out at the medical wards of Dr. B.C. Roy Memorial Hospital for Children, Calcutta, between January and September 1989. One hundred eleven hospitalized children up to the age of 5 years, receiving antibiotics for different medical problems, developed antibiotic associated diarrhea. Isolation of Clostridium difficile as sole pathogen was very low (3.6%) from these patients. Fecal samples of 111 case matched control children were also screened for C.difficile. Only 2.7% fecal samples of control children were positive for C.difficile. All the strains of C.difficile isolated from antibiotic associated diarrhea cases showed neutralisable cytotoxin in in vitro test. In contrast none of the strains isolated from control children showed cytotoxicity. This study suggests that C.difficile is not an important pathogen related to antibiotic associated diarrhea in children at this hospital.

Anti-Bacterial Agents↗
PubMed1993

Treatment of toxic epidermal necrolysis and Stevens-Johnson syndrome in children.

A retrospective study was carried out on eight consecutively treated children, 2 to 14 years of age, seven with toxic epidermal necrolysis and one with transitional-type Stevens-Johnson syndrome. The body surfaces affected ranged from 40% to 100%. Seven of the patients were taking a sulfonamide or anticonvulsant before the onset of their disease. Complete reepithelialization took an average of 15 days, but newly evolving lesions of the lips and oropharynx continued for approximately 4 more weeks. These lesions took an additional 2 to 4 weeks to heal. Only one of the children died.

Adolescent↗