PubMed Health⌕ Search

Biomedical subjects

A De

Publications and source records attributed to A De.

At least 55 records · Page 3Linked to original sources
PubMed1995

Isolation, cultivation and partial characterization of a kinetoplastid flagellate from the hindgut of the water bug, Lethocerus indicus.

A new species of kinetoplastid flagellates was isolated from the hindgut of the giant water bug, Lethocerus indicus, and successfully cultured in modified glycerol beef extract medium. Light and electron microscopic studies as well as growth in various culture media are described. The flagellates were in three different shapes and sizes in the hindgut of the host as well as in the culture medium. Each form of the parasite contained a kinetoplast which was located near the basal body of the flagellate. The ultrastructural features of this species exhibit great similarity to other species of Bodo. The flagellate ingested bacteria, grew in culture, and was identical with that observed in the hindgut of the bugs. The name Bodo indica has been proposed for this kinetoplastid flagellate.

Animals↗
PubMed1995

Antibiotic resistance pattern and R-plasmids of Acinetobacter calcoaceticus subsp. anitratus.

During a 6 month period from March 1990 to August 1990, a total of 159 strains of Acinetobacter calcoaceticus subsp. anitratus were isolated from various samples and studied for antibiotic resistance pattern to 12 drugs by Kirby-Bauer method. Ceftazidime and Netilmycin were the most sensitive drugs followed by Cefotaxime, Norfloxacin and Augmentin. All the strains were resistant to Chloramphenicol and Tetracycline. Commonest pattern of resistance was ACGKSTSu. Forty eight isolates were tested for R-plasmids by conjugation experiments using Nalidixic acid resistant E. coli K12F-Lac+ as the recipient strain. The incidence of R-plasmids was 81.25%.

Acinetobacter Infections↗
PubMed1994

Colocalization of prolactin and proliferating cell nuclear antigen in the anterior pituitary during estrogen-induced pituitary tumors.

Chronic estrogen treatment induces prolactin (PRL)-secreting pituitary tumors in laboratory animals. To determine earlier events of tumorigenesis, we studied cell proliferation in the pituitary following 7-30 days of estrogen administration in Fischer 344 rats. Immunohistochemical localization of proliferative cells by proliferating cell nuclear antigen (PCNA) staining and lactotropes by PRL staining revealed that estrogen treatment caused a time-dependent increase in the number of proliferative cells and lactotropes. Although the increase in lactotropic cell number paralleled the increase in PCNA-reactive cell number, only approximately 30% of lactotropes reacted simultaneously with the PCNA antibody. These results indicate that a subset population of lactotropes proliferates under the influence of estrogen during tumorigenesis.

Animals↗
PubMed1994

Cyclic AMP and ethanol interact to control apoptosis and differentiation in hypothalamic beta-endorphin neurons.

In this study we have determined the role of cyclic AMP on the function and differentiation of beta-endorphin (beta-EP) neurons in rat fetal hypothalamic cell cultures. Addition of Bt2cAMP or the cAMP elevating agent, forskolin, in cultures, dose and time dependently increased beta-endorphin secretion. The increased beta-EP secretion after Bt2cAMP or forskolin treatment was associated with proopiomelanocortin gene expression, enhanced neurite growth, and increased neuronal viability. Determination of internucleosomal cleavage of DNA by agarose gel electrophoresis revealed that apoptosis occurred in hypothalamic neurons during the first 6-8 days in culture. Addition of Bt2cAMP during this developmental period inhibited DNA degradation in hypothalamic neurons. Furthermore, incubation with various doses of ethanol, which is known to reduce intracellular levels of Bt2cAMP, increased DNA degradation in these cells. Ethanol-induced DNA degradation was blocked by concomitant incubation with Bt2cAMP. Histochemical identification of apoptotic cells following ethanol and Bt2cAMP treatments further revealed that apoptosis occurred in beta-EP neurons during the developmental period, and that ethanol increased and Bt2cAMP reduced apoptotic beta-EP cell numbers. These results suggest that ethanol neurotoxicity on beta-EP neurons during early neuronal differentiation involves an apoptotic process and that the cAMP signaling system plays an important role in controlling apoptosis and differentiation of the beta-EP neuronal system.

Animals↗
PubMed1994

Crystal structure of a disulfide-linked "trefoil" motif found in a large family of putative growth factors.

Porcine pancreatic spasmolytic polypeptide (PSP) belongs to a large family of homologous growth factor-like polypeptides characterized by a disulfide-linked "trefoil motif," duplicated and conserved in various family members. PSP contains two trefoil motifs, has several pharmacological actions on the gut, and has growth factor properties on epithelial cells in vitro. The human PSP analogue, human spasmolytic polypeptide, appears to be involved in many regenerative situations and, especially, in healing gastrointestinal ulcers. One member of the trefoil family, pS2, is secreted in approximately 50% of estrogen-dependent human breast carcinomas, which has led to its use as a tumor prognostic marker. Both pS2 and human spasmolytic polypeptide are also widely expressed in chronic gastrointestinal ulcerative conditions such as Crohn disease. Here we report the three-dimensional structure at 2.6-A resolution of a trefoil-containing protein, namely PSP, purified from porcine pancreas. The structure shows two homologous domains that share a supersecondary structure and disulfide bond pattern. The two domains pack asymmetrically giving rise to a number of protruding loops, exposed clefts, and an unusual electrostatic surface potential. Knowledge of the structure of PSP should allow the design of mutants to investigate further the function of PSP and other trefoil-containing peptides.

Amino Acid Sequence↗
PubMed1994

Overproduction and purification of C protein, the late gene transcription activator from phage Mu.

We report here the high-level overproduction and single-step purification for the C protein of bacteriophage Mu. Attempts to secrete the protein using the pelB signal sequence, in a T7 expression system, failed to yield the processed product. Moreover, the overexpressed fusion protein was inactive in DNA binding assays. In order to obtain the native protein, the sequences coding for the signal peptide were removed. The clones thus obtained upon induction overproduced the C protein, a significant amount of which was present in the S20 pellet fraction. The protein was recovered from this pellet by high salt extraction and purified by specific immunoaffinity chromatography. The purified protein was active in DNA binding assay. The final yield of the protein was 9 mg of approximately 95% purity from 1 g wet wt cells.

Bacteriophage mu↗
PubMed1994

Thyroidal stimulation of tubulin and actin in rat brain cytoskeleton.

In cultures of neonatal rat brain cells, labeled with 35S-methionine in the presence or absence of triiodothyronine (T3), the hormone promoted a significant enhancement of labeled tubulin and actin in the insoluble fraction (30,000 g pellet) of cell homogenate. To identify the specific sub-cellular fraction associated with this induction, organ cultures of 1 day rat cerebra were labelled with 35S-methionine in the presence and absence of T3 and the insoluble fraction (30,000 g pellet) was subfractionated into mitochondria, plasma membrane and cytoskeleton. Analysis of the labeled proteins by SDS-PAGE, autoradiography and densitometry revealed a T3-induced increase of 50-80% for both tubulin and actin, only in the cytoskeleton fraction without any significant effect on the other fractions. Similar results were obtained when plasma membrane or cytoskeleton were isolated directly from labeled cerebrum by conventional methods instead of fractionating from the 30,000 g pellet. Analysis of relative stimulation of labeled tubulin and actin by T3 in cytoskeleton fraction derived from primary cultures of neuronal (N) and glial (G) cells labeled with 35-methionine show that the stimulatory effect is predominantly on the N cells. Studies on the kinetics of induction of labeled tubulin and actin by T3 in the cytoskeleton fraction prepared from cerebra labeled with 35S-methionine for 2, 8 and 18 hrs revealed no significant difference at 2 hrs; at 8 hrs, an increased incorporation into both tubulin and actin was reproducibly seen in the controls relative to T3-treated samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1994

Engineering hyperexpression of bacteriophage Mu C protein by removal of secondary structure at the translation initiation region.

The structure at the translation initiation region (TIR) of mRNA has pronounced regulatory effects on gene expression. Our attempts to overexpress the C gene of bacteriophage Mu in a variety of expression vectors resulted in low yields of protein. Analysis of Mu C mRNA shows the potential to form a secondary structure involving a ribosome binding site and AUG codon. We have engineered the overproduction of the protein using a PCR-aided cloning approach to remove the sequences involved in the formation of this secondary structure. The overexpressing clone, under the control of T7 gene 10 promoter in a T7 expression system yielded > 30% of total cell protein. The difference in mRNA structure between expressing and non-expressing clones was confirmed by electrophoretic analysis of run-off transcripts. The overexpressed protein was purified in a single step by site-specific DNA affinity chromatography. The purified recombinant protein was active in band shift assays. DNA binding activity required Mg2+ and was weak in the presence of Mn2+. Cd2+ or Zn2+ could not support DNA binding. Under optimal conditions, the equilibrium binding constant (Kapp) was determined to be 2 x 10(12) M-1.

Bacteriophage mu↗
PubMed1993

Enteropathogenic bacteria in river Ganges in Varanasi.

A bacteriological study of the river Ganges in Varanasi was carried out from December 1985 to November 1987. In all 407 water samples were collected, 335 from bathing ghats and 72 from sewage openings and were examined for the presence of enteropathogenic bacteria. Vibrio cholerae 0-1 (1.72%), Non 0-1 Vibrio cholera (3.69%), Vibrio fluvialis (0.74%), Aeromonas sp. (0.49%), Plesiomonas sp. (0.25%), Salmonella sp. (0.98%) and Shigella sp. (1.23%) were isolated from both ghats and sewage openings along with Pseudomonas sp., Proteus sp., E. coli., etc. This indicates that water of the river Ganges is potentially hazardous to the health of the bathers and is not suitable for drinking. The discharge of raw sewage into the river and its diversion beyond the city, downstream, by installation of pumps have failed to improve the quality of water.

Enterobacteriaceae↗
PubMed1992

Crystallization and preliminary X-ray diffraction analysis of a plant ribonuclease from the seeds of the bitter gourd Momordica charantia.

Single crystals of ribonuclease Mc, a new class of plant ribonuclease from the seeds of the bitter gourd, were obtained from solutions of polyethylene glycol 8000 by the hanging-drop vapour diffusion method. The crystals belong to the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 67.28 A, b = 75.21 A, c = 38.54 A. The assumption of one monomer per asymmetric unit gives rise to a Vm value of 2.29 A3/Da. The crystals diffract beyond 2.0 A resolution and are suitable for high resolution X-ray structure analysis.

Crystallization↗
PubMed1992

Crystallization and preliminary X-ray diffraction studies of pancreatic spasmolytic polypeptide.

Pancreatic spasmolytic polypeptide (PSP) isolated from porcine pancreas has been crystallized by the hanging drop vapour diffusion method. The crystals belong to the space group I222 or I2(1)2(1)2(1) with cell dimensions a = 181.9 A, b = 54.5 A, c = 72.9 A. The crystals diffract to at least 2.5 A resolution and the asymmetric unit contains two molecules (Vm = 3.9 A3/Da) with a solvent content of 68% as determined by density measurements of the crystals. The self-rotation function suggests that the two molecules within the asymmetric unit are related by a 2-fold axis at either 30 degrees or 60 degrees from a in a plane perpendicular to the b axis.

Animals↗
PubMed1992

Mechanism of ribosomal subunit association: oligodeoxynucleotides as probes.

From the kethoxal treatment data [Herr, W.; Chapman, N.M.; Noller, H.F. (1979) J. Mol. Biol. 130, 433-439] some regions of ribosomal RNAs are thought to be responsible for the association of 30S and 50S ribosomes of E. coli to form 70S ribosomes. In order to test this possibility about a dozen oligodeoxynucleotides complementary to the suspected regions of rRNAs were synthesised. Their association with ribosomes and naked rRNAs was tested by the gel filtration technique. In order to check the effects on the ribosomal subunit association or rRNA association either intact 30S and 50S ribosomes or naked 16S and 23S rRNAs were preincubated with the individual oligodeoxynucleotide and its effect was checked by density gradient centrifugation followed by UV absorbance monitoring. Some oligodeoxynucleotides interfered with either subunit association or 16S RNA and 23S RNA association, some with both. These data clearly indicate that RNA-RNA interaction plays the major role in ribosomal subunit association.

Base Sequence↗
PubMed1991

Production of interleukin-1 and tumour necrosis factor in non-Hodgkin's lymphoma patients.

Peripheral blood monocytes from non-Hodgkin's lymphoma (NHL) patients were assessed for the monocyte functions with respect to their ability to secrete interleukin-1 and tumour necrosis factor (TNF) and their cytotoxic potential to tumour target WEHI 164 clone 13. Our results indicate comparable levels of interleukin-1 and TNF production by NHL patients. The cytotoxic potential by monocytes was also not depressed in these patients. The data obtained suggest normal monocyte functions in NHL patients.

Adult↗
PubMed1991

Thyroidal stimulation of tubulin and actin in primary cultures of neuronal and glial cells of rat brain.

The influence of triiodothyronine (T3) on the level of tubulin and other proteins in primary cultures of neuronal (N) and glial (G) cells from rat brain has been investigated. Quantitation of tubulin by [3H]colchicine binding assay revealed that when cells from 1 day rat brain were cultured for 18 hr with physiological doses (0.5-5 nM) of T3, the hormone elicited 35-40% increase in the soluble (30,000 g supernatant) tubulin content of G cells only. This stimulation was age-dependent and occurred neonatally at a time corresponding to the onset of synaptogenesis. In mouse and chick brain also, [3H]colchicine binding assay showed a similar selective stimulation of the soluble tubulin content of G cells by T3 with virtually no effect on N cells. However, SDS-polyacrylamide gel electrophoresis of the total proteins in the 30,000 g supernatants from N and C cells of rat brain, labeled for 18 hr with [14C]leucine in the presence of T3, revealed that T3 elicited 2-3-fold enhancement of radiolabeled tubulin in the N cells which is relatively greater than the 1.5-fold increase seen in the G cells. Analysis of the autoradiograms of these labeled proteins also revealed that in addition to tubulin, T3 stimulated the accumulation of radiolabeled actin by 1.5- and 2-fold in N cells and G cells respectively. Similar electrophoretic analysis of the solubilized labeled proteins in the 30,000 g pellets from N and G cells indicated that the failure to detect the stimulation of tubulin in the 30,000 g supernatants from N cells by [3H]colchicine binding assay could be at least partly due to rapid translocation of the dimeric soluble tubulin into insoluble membrane fractions or due to presence of higher oligomeric forms of tubulin which are insensitive to [3H]colchicine binding assay.

Actins↗
PubMed1991

Identification of heterogeneity in human isolates of Giardia lamblia by isoenzyme studies.

Electrophoretic mobility patterns of six enzymes, viz. alkaline phosphatase E.C. 3.1.3.1., acid phosphatase E.C. 3.1.3.2., malic enzyme E.C. 1.1.1.40., phosphoglucomutase E.C. 2.7.5.1., isocitrate dehydrogenase E.C. 1.1.1.42., glucose-6-phosphate dehydrogenase E.C. 1.1.1.49 of two axenically cultured human Giardia lamblia isolated from India (PD-1 and PD-2) and one strain from Portland, Oregon, USA (P-1) were compared using polyacrylamide gel electrophoresis (PAGE). Based on the difference in the mobility patterns of the enzymes phosphoglucomutase, isocitrate dehydrogenase and malic enzyme, the PD-1 and PD-2 isolates appeared to be quite different from P-1. In the present study, the isocitrate dehydrogenase and alkaline phosphatase enzymes were used for the first time for differentiation of Giardia isolates. In the case of PD-1, two alkaline phosphatase bands could be seen whereas only one band was observed in PD-2 and P-1. Thus, the three strains could be grouped into three different zymodemes. These findings reveal the significant heterogeneity in G. lamblia isolates both from widely separated areas and within a single region. Heterogeneity among G. lamblia strains may explain the variable clinical manifestations, host response and treatment efficacy characteristic of human giardiasis.

Acid Phosphatase↗
PubMed1991

Effect of high dose intravenous pulse dexamethasone on lymphocyte phenotypes.

The lymphocyte phenotypes were enumerated in 10 patients with collagen diseases at 0 h, 4 h, 24 h and 7 days after a megadose (100 mg) iv pulse dexamethasone. A significant decrease in CD3 (from a mean of 2324.3/mm3 to 705.9/mm3) and CD4 (from a mean of 1642.6 to 317.6/mm3) cells was observed at 4 h, which recovered partially by 24 h (186.7 and 1226.3/mm3 respectively) and completely at 7 days (2496.1 and 1838.4/mm3). A transient decrease in CD8 cells at 4 h was also observed. There was no significant effect on B cells.

Adolescent↗