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Biomedical subjects

A Das

Publications and source records attributed to A Das.

At least 181 records · Page 10Linked to original sources
PubMed1997

Primary cutaneous zygomycosis due to Saksenaea vasiformis and Apophysomyces elegans.

We report three cases of primary cutaneous zygomycosis due to either Saksenaea vasiformis (two patients) or Apophysomyces elegans (one patient). Extensive surgical debridement helped two patients recover from their infections. The underlying disease in the one patient who died was diabetes mellitus. We reviewed the literature on primary cutaneous zygomycosis and found that S. vasiformis and A. elegans were the etiologic agents in 16 and 13 earlier cases, respectively.

Adult↗
PubMed1997

Technology coverage decisions by health care plans and considerations by medical directors.

OBJECTIVES: Decisions made by private health care plans as to whether to cover new medical technology have a significant impact on access, diffusion, and costs. This study describes the variation in health plan coverage of different laser technologies and the types of considerations used in making coverage decisions for them. METHODS: In a cross-sectional national survey of medical directors at private plans, medical directors indicated current coverage of 15 different laser therapies, and then ranked the top five considerations both in favor and against recommending coverage for three of the laser therapies (angioplasty, discectomy, and photodynamic therapy). The influence of explicit clinical information and/or plan characteristics on coverage and the importance of considerations was examined through multivariate analyses (multiple logistic or linear regression analysis). RESULTS: Overall, 231 medical directors responded from plans representing 66% and 72% of persons in US health maintenance organization and indemnity plans, respectively. Current coverage for 13 of the 15 laser therapies varied between 20% and 90%. For-profit and indemnity plans covered approximately two more of the different laser technologies than nonprofit plans and health maintenance organizations. Considerations most frequently listed in favor of and against recommending coverage across the three laser technologies were clinical, economic, and regulatory. Legal, competitive, and compassionate concerns were listed less frequently. Considerations were not uniform across laser therapies; they reflected the specifics of the technology under review. Plan characteristics influenced the ranking of considerations as well. For instance, health maintenance organizations were two to three times more likely than indemnity plans to list potential for decreased cost in favor of recommending coverage. CONCLUSIONS: These findings demonstrate that there is substantial variation in coverage of new technologies, indicating that a large proportion of the population covered by private health plans are ineligible for treatments that are routinely available to others. A greater range of medical therapy may be available for persons enrolled in indemnity and for-profit plans should their physicians choose to prescribe it. Clinical and economic considerations, including cost-effectiveness, predominate in coverage decisions for new technologies. The importance of considerations appears sensitive not only to specific clinical information, however, but also to characteristics of health plans.

Cross-Sectional Studies↗
PubMed1997

Fine needle aspiration (FNA) cytology of extra-adrenal paragangliomas.

We studied nine histologically proved cases of extra-adrenal paragangliomas. Of these, eight cases were correctly diagnosed preoperatively by FNA cytology. Salient cytological features included clusters and discretely scattered cells, with occasional acinar configuration. The cells showed moderate to abundant slightly basophilic cytoplasm with ill-defined margins and round to oval nuclei with mild to marked nuclear pleomorphism. Fine reddish intracytoplasmic granules were also noted (six cases). Cytological features along with clinical data are quite diagnostic of paragangliomas. A correct preoperative cytological diagnosis helps to prevent undue surgical complications.

Adult↗
PubMed1997

Craniofacial zygomycosis caused by Apophysomyces elegans.

A fatal case of craniofacial zygomycosis caused by Apophysomyces elegans in a 52-year-old man was diagnosed by the presence of broad aseptate, branched hyaline hyphae in tissue from paranasal sinuses and surrounding areas, and isolation of the fungus from the same tissue. The patient suffered from idiopathic myelofibrosis as underlying disease, he was thrombocytopenic and was mildly hyperglycaemic. The infection represents the second case of craniofacial zygomycosis due to A. elegans.

Blood Vessels↗
PubMed1997

Limited utility of ICD-10 and DSM-IV classification of dissociative and conversion disorders in India.

Studies of psychiatric out-patients from India have found that diagnosis of some of the subcategories of the dissociative and conversion disorders of the ICD and DSM classificatory systems are rarely made in this setting. Moreover, it was found that a significant percentage of patients seen in psychiatric practice may not fit into the defined subcategories of dissociative (conversion) disorders of these systems of classification. We studied the prevalence of various ICD-10 and DSM-IV categories of dissociative (conversion) disorders and our own proposed category of 'brief dissociative stupor' (BDS), among all the in-patients of a psychiatric unit in a general teaching hospital, over a 2-year period. There were 18 patients who fulfilled our criteria for BDS and 18 patients in the second group which included all of the remaining subjects with a diagnosis of any other subcategory of dissociative disorder according to ICD-10. Our analysis revealed that there were no patients with a diagnosis of dissociative amnesia, fugue, stupor, trance and possession disorders or identity disorders. There were significantly more female patients in the BDS group, and they also had significantly more comorbid Axis-I diagnoses and panic attacks. Since 50% of our patients fulfilled the criteria for BDS, there is clearly a need for further studies to establish the prevalence of this subcategory in patients from other centres. The classification of these patients with this phenomenology is problematic. Inclusion of a subcategory of dissociative non-epileptic seizures, instead of dissociative convulsions, should improve the classification of dissociative (conversion) disorders.

Adolescent↗
PubMed1997

Delineation of the interaction domains of Agrobacterium tumefaciens VirB7 and VirB9 by use of the yeast two-hybrid assay.

The Agrobacterium tumefaciens VirB proteins are postulated to form a transport pore for the transfer of T-DNA. Formation of the transport pore will involve interactions among the VirB proteins. A powerful genetic method to study protein-protein interaction is the yeast two-hybrid assay. To test whether this method can be used to study interactions among the VirB membrane proteins, we studied the interaction of VirB7 and VirB9 in yeast. We recently demonstrated that VirB7 and VirB9 form a protein complex linked by a disulfide bond between cysteine 24 of VirB7 and cysteine 262 of VirB9 (L. Anderson, A. Hertzel, and A. Das, Proc. Natl. Acad. Sci. USA 93:8889-8894, 1996). We now demonstrate that VirB7 and VirB9 interact in yeast, and this interaction does not require the cysteine residues essential for the disulfide linkage. By using defined segments in fusion constructions, we mapped the VirB7 interaction domain of VirB9 to residues 173 to 275. In tumor formation assays, both virB7C24S and virB9C262S expressed from a multicopy plasmid complemented the respective deletion mutation, indicating that the cysteine residues may not be essential for DNA transfer.

Agrobacterium tumefaciens↗
PubMed1997

Composition and primary structure of the F1F0 ATP synthase from the obligately anaerobic bacterium Clostridium thermoaceticum.

The subunit composition and primary structure of the proton-translocating F1F0 ATP synthase have been determined in Clostridium thermoaceticum. The isolated enzyme has a subunit composition identical to that of the F1F0 ATP synthase purified from Clostridium thermoautotrophicum (A. Das, D. M. Ivey, and L. G. Ljungdahl, J. Bacteriol. 179:1714-1720, 1997), both having six different polypeptides. The molecular masses of the six subunits were 60, 50, 32, 17, 19, and 8 kDa, and they were identified as alpha, beta, gamma, delta, epsilon, and c, respectively, based on their reactivity with antibodies against the F1 ATPase purified from C. thermoautotrophicum and by comparing their N-terminal amino acid sequences with that deduced from the cloned genes of the C. thermoaceticum atp operon. The subunits a and b found in many bacterial ATP synthases could not be detected either in the purified ATP synthase or crude membranes of C. thermoaceticum. The C. thermoaceticum atp operon contained nine genes arranged in the order atpI (i), atpB (a), atpE (c), atpF (b), atpH (delta), atpA (alpha), atpG (gamma), atpD (beta), and atpC (epsilon). The deduced protein sequences of the C. thermoaceticum ATP synthase subunits were comparable with those of the corresponding subunits from Escherichia coli, thermophilic Bacillus strain PS3, Rhodospirillum rubrum, spinach chloroplasts, and the cyanobacterium Synechococcus strain PCC 6716. The analysis of total RNA by Northern hybridization experiments reveals the presence of transcripts (mRNA) of the genes i, a, and b subunits not found in the isolated enzyme. Analysis of the nucleotide sequence of the atp genes reveals overlap of the structural genes for the i and a subunits and the presence of secondary structures (in the b gene) which could influence the posttranscriptional regulation of the corresponding genes.

Amino Acid Sequence↗
PubMed1997

Purification and reconstitution into proteoliposomes of the F1F0 ATP synthase from the obligately anaerobic gram-positive bacterium Clostridium thermoautotrophicum.

The proton-translocating F1F0 ATP synthase from Clostridium thermoautotrophicum was solubilized from cholate-washed membranes with Zwittergent 3-14 at 58 degrees C and purified in the presence of octylglucoside by sucrose gradient centrifugation and ion-exchange chromatography on a DEAE-5PW column. The purified enzyme hydrolyzed ATP at a rate of 12.6 micromol min(-1) mg(-1) at 58 degrees C and pH 8.5. It was composed of six different polypeptides with molecular masses of 60, 50, 32, 19, 17, and 8 kDa. These were identified as alpha, beta, gamma, delta, epsilon, and c subunits, respectively, as their N-terminal amino acid sequences matched the deduced N-terminal amino acid sequences of the corresponding genes of the atp operon sequenced from Clostridium thermoaceticum (GenBank accession no. U64318), demonstrating the close similarity of the F1F0 complexes from C. thermoaceticum and C. thermoautotrophicum. Four of these subunits, alpha, beta, gamma, and epsilon, constituted the F1-ATPase purified from the latter bacterium. The delta subunit could not be found in the purified F1 although it was present in the F1F0 complex, indicating that the F0 moiety consisted of the delta and the c subunits and lacked the a and b subunits found in many aerobic bacteria. The c subunit was characterized as N,N'-dicyclohexylcarbodiimide reactive. The F1F0 complex of C. thermoautotrophicum consisting of subunits alpha, beta, gamma, delta, epsilon, and c was reconstituted with phospholipids into proteoliposomes which had ATP-Pi exchange, carbonylcyanide p-trifluoromethoxy-phenylhydrazone-stimulated ATPase, and ATP-dependent proton-pumping activities. Immunoblot analyses of the subunits of ATP synthases from C. thermoautotrophicum, C. thermoaceticum, and Escherichia coli revealed antigenic similarities among the F1 subunits from both clostridia and the beta subunit of F1 from E. coli.

Adenosine Triphosphate↗
PubMed1997

Atypical post-kala-azar dermal leishmaniasis resembling histoid leprosy.

An adult male with atypical lesions of post-kala-azar dermal leishmaniasis (PKDL) is described. He had extensive ulcerated noduloplaque lesions on his hands, feet and genitalia. He had been diagnosed and treated for leprosy in the past. He came from an area endemic for kala-azar and leprosy and had a previous history of kala-azar. There was an abundance of Leishman Donovan bodies in slitskin smears and in histopathology sections. There was a good therapeutic response to sodium stibogluconate. An ulcerative variant of PKDL has been described but is extremely rare. Extensive lesions with ulceration have not been described before to the best of our knowledge. The epidemiological significance of the case is discussed.

Adult↗
PubMed1997

Primary gastrointestinal lymphoma--disease spectrum and management: a 15-year review from north India.

OBJECTIVE: To analyze retrospectively the disease spectrum and outcome of primary gastrointestinal lymphoma (PGIL) in a tertiary referral center in north India. MATERIAL: Seventy five patients presenting with PGIL between January 1971 and December 1985 were evaluated. RESULTS: The 49 males and 26 females were aged 3.5-69 years (mean 34) at presentation. Abdominal pain, weight loss and vomiting were cardinal symptoms at presentation; the stomach was the most common site of involvement. Histologically, a majority of patients were classified as having diffuse poorly-differentiated lymphocytic lymphoma (46.7%) and diffuse histiocytic type (30.7%). Twenty seven (36%) patients had stage I disease, 31 (40%) stage II, 11 (14.7%) stage III, and 6 (8%) stage IV. At laparotomy, primary resection and anastomosis was carried out in 66 patients, while only biopsies were taken in nine. Forty eight patients received adjuvant radiation with or without chemotherapy. The mean follow-up was 3.9 years (range 1-14). The 5-year actuarial survival was 34%, 25% and 16% for stages I, II, and higher-stage disease, respectively. The survival was significantly better (p < 0.01) for gastric location (44%) compared to other sites (24%). CONCLUSION: PGIL was more common in the 3rd and 4th decades of life, with the stomach being the predominant site of involvement. Survival was better among patients with stages I and II disease, and gastric location of lesion.

Adolescent↗
PubMed1997

Expression of Rhizobium meliloti symbiotic promoters in Azorhizobium caulinodans.

Plasmids containing Rhizobium meliloti symbiotic promoters P1 (promoter of nifHDK) and P2 (promoter of fixABCX) when mobilized into the cells of Azorhizobium caulinodans strain IRBG 46 showed strong expression of these promoters under free-living microaerobic as well as symbiotic conditions. Under free-living conditions microaerobiosis (3% or less O2) was found to be sufficient to activate these promoters; expression being higher at 1% than at 3% O2 concentration. Under symbiotic conditions the expression was much more stronger-with bacteroids in stem nodules showing higher expression than those in root nodules. Under both the conditions expression of the promoters in the native R. meliloti strain Rm102F34 was lower than that in the A. caulinodans strain IRBG 46. The results suggest a functional homology of these promoters in the heterologous background of A. caulinodans.

Fabaceae↗
PubMed1996

Agrobacterium tumefaciens VirB7 and VirB9 form a disulfide-linked protein complex.

Agrobacterium tumefaciens VirB proteins are essential for gene transfer from bacteria to plants. These proteins are postulated to form a transport pore to allow transfer of the T-strand DNA intermediate. To study the function of the VirB proteins in DNA transfer, we developed an expression system in A. tumefaciens. Analysis of one VirB protein, VirB9, by Western blot assays showed that under nonreducing conditions VirB9, when expressed alone, migrates as a approximately 31-kDa band but that it migrates as a approximately 36-kDa band when expressed with all other VirB proteins. The 36-kDa band is converted to the 31-kDa band by the reducing agent 2-mercaptoethanol. Using strains that contain a deletion in a defined virB gene and strains that express specific VirB proteins, we demonstrate that the 36-kDa band is composed of VirB9 and VirB7 that are linked to each other by a disulfide bond. Mutational studies demonstrate that cysteine residues at positions 24 of VirB7 and 262 of VirB9 participate in the formation of this complex.

Agrobacterium tumefaciens↗
PubMed1996

A major tyrosine-phosphorylated protein of Trypanosoma brucei is a nucleolar RNA-binding protein.

We have previously identified a set of tyrosine-phosphorylated proteins with apparent molecular masses of 44-46 kDa as some of the major tyrosine phosphorylated species in the protozoan parasite Trypanosoma brucei. We now show that these molecules, herein named Nopp44/46, are localized in the nucleolus. Using monoclonal antibodies, we have isolated Nopp44/46 cDNA clones from expression libraries. Sequence analysis reveals that the predicted amino acid sequence of the molecule is composed of an N-terminal unique region, an internal acidic region, and C-terminal repeat region. Analysis of the cDNA clones and genomic Southern analysis indicated that Nopp44/46 belongs to a multigene family in which different gene copies are very similar but vary in the number of repeats. Interestingly, the repetitive amino acid sequence motif contains multiple RGG (Arg-Gly-Gly) boxes characteristic of RNA-binding proteins. In vitro binding experiments demonstrated that Nopp44/46 is indeed capable of binding nucleic acids. Competition experiments with different RNA homopolymers demonstrated that Nopp44/46 preferentially binds to poly(U). These studies suggest that Nopp44/46 may play a role in RNA metabolism in trypanosomes and raise the possibility that tyrosine phosphorylation may regulate the process.

Amino Acid Sequence↗
PubMed1996

The length of the cervix and the risk of spontaneous premature delivery. National Institute of Child Health and Human Development Maternal Fetal Medicine Unit Network.

BACKGROUND: The role of the cervix in the pathogenesis of premature delivery is controversial. In a prospective, multicenter study of pregnant women, we used vaginal ultrasonography to measure the length of the cervix; we also documented the incidence of spontaneous delivery before 35 weeks' gestation. METHODS: At 10 university-affiliated prenatal clinics, we performed vaginal ultrasonography at approximately 24 and 28 weeks of gestation in women with singleton pregnancies. We then assessed the relation between the length of the cervix and the risk of spontaneous preterm delivery. RESULTS: We examined 2915 women at approximately 24 weeks of gestation and 2531 of these women again at approximately 28 weeks. Spontaneous preterm delivery (at less than 35 weeks) occurred in 126 of the women (4.3 percent) examined at 24 weeks. The length of the cervix was normally distributed at 24 and 28 weeks (mean [+/- SD], 35.2 +/- 8.3 mm and 33.7 +/- 8.5 mm, respectively). The relative risk of preterm delivery increased as the length of the cervix decreased. When women with shorter cervixes at 24 weeks were compared with women with values above the 75th percentile, the relative risks of preterm delivery among the women with shorter cervixes were as follows: 1.98 for cervical lengths at or below the 75th percentile (40 mm), 2.35 for lengths at or below the 50th percentile (35 mm), 3.79 for lengths at or below the 25th percentile (30 mm), 6.19 for lengths at or below the 10th percentile (26 mm), 9.49 for lengths at or below the 5th percentile (22 mm), and 13.99 for lengths at or below the 1st percentile (13 mm) (P < 0.001 for values at or below the 50th percentile; P = 0.008 for values at or below the 75th percentile). For the lengths measured at 28 weeks, the corresponding relative risks were 2.80, 3.52, 5.39, 9.57, 13.88, and 24.94 (P < 0.001 for values at or below the 50th percentile; P = 0.003 for values at the 75th percentile). CONCLUSIONS: The risk of spontaneous preterm delivery is increased in women who are found to have a short cervix by vaginal ultrasonography during pregnancy.

Cervix Uteri↗