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Biomedical subjects

A Ray

Publications and source records attributed to A Ray.

At least 109 records · Page 6Linked to original sources
PubMed1997

Modulation of gamma glutamyl transpeptidase activity in lymphoid system by organochlorine pesticides in rats.

Effects of 1,1,1,-trichloro-2,2-bis (p-chlorophenyl) ethane (DDT) and lindane were studied on gamma glutamyl transpeptidase (GGT) activity in different tissues of the lymphoid system in rats. DDT (100 or 200 ppm) and lindane (30 or 80 ppm) exposure for 8 weeks suppressed the GGT activity in a dose dependent manner in thymus and macrophage. In spleen, significant decrease in the enzyme activity was observed at higher exposure (200 ppm DDT or 80 ppm lindane) levels. Lindane suppressed GGT activity at both 30 or 80 ppm dose levels, while DDT reduced the GGT activity at 200 ppm but not at 100 ppm exposure in lymphocyte. The study indicates the possibility of using GGT as an effective and consistent biochemical marker for immunotoxicity of xenobiotics and other environmental stressors.

Animals↗
PubMed1996

Maternal effects of the short integument mutation on embryo development in Arabidopsis.

Maternal gene products deposited in an animal egg determine the polarity of embryonic axes and regulate embryonic cell-cell communication important for morphogenesis. Here we report the first maternal-effect embryo-defective mutation discovered in a plant. Recessive mutations in the SHORT INTEGUMENT (SIN1) gene in Arabidopsis were previously shown to influence ovule development and flowering time. Here we show that a sin1 mutation has a pronounced maternal effect on zygotic embryo development. A homozygous sin1 mutant embryo is normal when nursed by a sin1/+ heterozygous maternal sporophyte. Strikingly, a sin1 or a sin1/+ embryo that is nursed by a sin1 homozygous maternal sporophyte develops morphogenetic defects in the apical-basal and radial axes. The defects resemble those seen in some zygotic-effect embryonic pattern formation mutants. These results imply that in maternal cells the SIN1 gene either codes for or controls the production of a diffusible morphogen necessary for proper zygotic embryogenesis.

Arabidopsis↗
PubMed1996

Interactions of aristololactam beta-D-glucoside with right-handed and left-handed forms of synthetic deoxyribonucleic acid: spectroscopic and thermodynamic study.

The interaction of aristololactam beta-D-glucoside (ADG) with different polymorphic structures of poly(dG-me5dC).poly(dG-me5dC), poly(dG-dC).poly(dG-dC), and poly(dI-dC). poly(dI-dC) has been studied by spectrophotometric, spectrofluorimetric, circular dichroism, UV melting profiles, and thermodynamic analysis. The binding of ADG to B-form duplexes is characterized by the typical bathochromic and hypochromic effects in the absorption spectrum, quenching of steady-state fluorescence intensity, a decrease in fluorescence quantum yield of ADG, an increase in fluorescence polarization anisotropy, an increase of thermal transition temperature, and perturbation in circular dichroic spectrum. Scatchard analysis indicates that ADG binds to the right-handed form of each polymer in a noncooperative manner. Comparative binding parameters determined from absorbance titration by Scatchard analysis, employing the excluded site model, indicate a stronger binding of ADG to the B-form of poly(dG-me5-dC). poly(dG-me5dC) than to the B-form of poly(dG-dC).poly(dG-dC) or poly(dI-dC). poly(dI-dC). Thermodynamic parameters (delta G degree, delta H degree, and delta S degree) obtained by van't Hoff analysis of the data show that the process of binding to all B-form duplexes is exothermic and enthalpy driven as characterized by a favorable negative enthalpy change (delta H degree). The binding is opposed by a negative entropy change (delta S degree) contribution. Conformational changes indicate that the alkaloid converts the left-handed form of poly(dG-dC). poly(dG-dC), and its methylated analogue and high salt form of poly(dI-dC). poly(dI-dC) to a bound right-handed form, while it inhibits both the rate and extent of the B to Z transition. These studies reveal that ADG binds strongly to B-form polymers while it does not bind to polymers of Z-form.

Alkaloids↗
PubMed1996

Thermodynamics of the interactions of sanguinarine with DNA: influence of ionic strength and base composition.

Using a combination of spectrophotometric and spectrofluorimetric techniques, we report the first thermodynamic characterization of sanguinarine binding to a series of natural and synthetic host DNA duplexes over a wide range of temperature and sodium concentration. The binding isotherms fit reasonably well to the neighbour exclusion model. The salt and temperature dependence of the binding constants is used to estimate the thermodynamic parameters involved in the interaction of the alkaloid with DNA. The resulting binding data are found to be sensitive to the ionic strength of the medium, base composition and sequence of base pairs. When the sodium ion concentration is increased from 0.005 M to 0.5 M, the binding free energy changes vary in a range from -8.47 to -7.1 kcal mol-1, which corresponds to a binding constant range from 1.85 x 10(6) to 1.8 x 10(5) M-1 at 20 degrees C. More distinct is the spread in the binding enthalpy changes which range from -6.35 to -2.62 kcal mol-1 corresponding to binding entropy changes from +7.22 to +15.3 cal K-1 mol-1 at 20 degrees C. On the other hand when the GC content of the host DNA duplexes is increased, the binding free energy varies in a range from -7.28 to -8.58 kcal mol-1 with the binding enthalpy changes ranging from -0.46 to -14.31 kcal mol-1, while corresponding binding entropy changes range from +23.3 to -19.56 cal K-1 mol-1 at 20 degrees C. Sanguinarine binding to natural DNAs and homo- and heteropolymers of AT is characterized by negative enthalpy changes and positive entropy changes, while binding to homo- and heteropolymers of GC is reflected by both negative enthalpy changes and entropy changes. Possible molecular contributions towards sign and magnitude of the thermodynamic parameters and their dependence on ionic strength, base composition and sequences, are discussed.

Alkaloids↗
PubMed1996

Rhinovirus stimulation of interleukin-6 in vivo and in vitro. Evidence for nuclear factor kappa B-dependent transcriptional activation.

To further understand the biology of rhinovirus (RV), we determined whether IL-6 was produced during RV infections and characterized the mechanism by which RV stimulates lung cell IL-6 production. In contrast to normals and minimally symptomatic volunteers, IL-6 was detected in the nasal washings from patients who developed colds after RV challenge. RV14 and RV1A, major and minor receptor group RVs, respectively, were potent stimulators of IL-6 protein production in vitro. These effects were associated with significant increases in IL-6 mRNA accumulation and gene transcription. RV was also a potent stimulator of IL-6 promoter-driven luciferase activity. This stimulation was modestly decreased by mutation of the nuclear factor (NF)-IL-6 site and abrogated by mutation of the NF-kappa B site in this promoter. An NF-kappa B-DNA binding activity, mediated by p65, p50, and p52 NF-kappa B moieties, was rapidly induced in RV-infected cells. Activator protein 1-DNA binding was not similarly altered. These studies demonstrate that IL-6 is produced during symptomatic RV infections, that RVs are potent stimulators of IL-6 elaboration, and that RV stimulation IL-6 production is mediated by an NF-kappa B-dependent transcriptional stimulation pathway. IL-6 may play an important role in the pathogenesis of RV infection, and NF-kappa B activation is likely to be an important event in RV-induced pathologies.

Adult↗
PubMed1996

A mutant of Pseudomonas aeruginosa that lacks c-type cytochromes has a functional cyanide-insensitive oxidase.

Using transposon mutagenesis and screening for the loss of the ability to oxidise the artificial electron donor N,N,N',N'-tetramethyl-p-phenylenediamine, we have isolated a mutant of Pseudomonas aeruginosa that lacks all c-type cytochromes. This mutant is unable to grow anaerobically with nitrate as a terminal electron acceptor. Analysis of its respiratory function indicates that the mutant has lost its cytochrome c oxidase-terminated respiratory pathway but the cyanide-insensitive oxidase-terminated branch remains functional. Complementation of the mutant by in vivo cloning led to recovery of the wild-type characteristics. These data are consistent with the idea that the cyanide-insensitive respiratory pathway does not contain haem c and that the pathway's terminal oxidase is a quinol oxidase.

Electron Transport Complex IV↗
PubMed1996

Regulation of NFIL-6 and IL-6 expression by basic fibroblast growth factor in osteoblasts.

We determined whether basic fibroblast growth factor (bFGF) regulated the expression of IL-6 and NFIL-6 in osteoblasts. In mouse osteoblastic MC3T3-E1 cells, bFGF (10(-8) M) increased NFIL-6 mRNA 2-fold at 30 minutes and 3-fold at 2 h. IL-6 mRNA was increased by bFGF 10(-8) M after 1 h. IL-6 protein was detectable in control cultures but was significantly increased by bFGF (10(-8) M) at 4 h. Immunofluorescence analysis of MC3T3-E1 cells showed primarily cytoplasmic and perinuclear NFIL-6 staining in control cultures while bFGF-treated cells showed increased NFIL-6 staining at 2 and 4 h. Western blotting revealed that bFGF increased NFIL-6 protein at 2 h. In calvarial mouse osteoblasts, bFGF 10(-8) M induced IL-6 mRNA as early as 1 h and significantly increased IL-6 protein levels as early as 2 h. In conclusion, bFGF stimulates IL-6 and NFIL-6 mRNA in osteoblasts. The increase in NFIL-6 mRNA was associated with increased NFIL-6 protein. The increase in IL-6 mRNA was also associated with increased IL-6 protein. We propose that activations of NFIL-6 and IL-6 may be important mediators of the effects of bFGF on bone cells.

Animals↗
PubMed1996

Critical cooling and warming rates to avoid ice crystallization in small pieces of mammalian organs permeated with cryoprotective agents.

Measurements were made by differential scanning calorimetry on small pieces of rabbit kidney permeated with 2, 3-butanediol containing mainly the levo- and dextro-isomers. The critical cooling rates necessary to vitrify the pieces of organ, and the corresponding critical warming rates which are required to avoid crystallization in the vitrified samples, were determined. The dynamic method used for these determinations is described. The glass-forming tendency and the stability of the amorphous state were both greater in the kidney tissue samples than in the bulk cryoprotective solution. This result is discussed in the context of the lowering of the freezing point of water in emulsions and the promotion of supercooling in hydrogels and porous materials. In corresponding experiments with rat hearts impregnated with 1,2-propanediol, only the critical warming rate was reduced.

Animals↗
PubMed1996

Prevalence of serum antibodies to synthetic peptides to HPV16 epitopes among Indian women with cervical neoplasia.

Serum samples from 38 Indian women with cervical intraepithelial neoplasia (CIN) and cancer along with 20 control women were analysed for IgG antibodies against a panel of four synthetic peptides derived from early and late gene open reading frames of HPV16. The cervical tissue samples from these patients were also subjected to PCR in order to detect the presence of human papilloma viruses (HPVs) type 6, 11 and 16 DNA, using a set of primers for the E6 open reading frames in order to establish the acquisition of HPV infection. E2, E6 and L1 peptides of HPV16 were found to be highly reactive with the patients' sera, and a significant prevalence of antibodies to E6, E2 and L1 (P < 0.01) was observed among women with CIN, while antibodies to E6 peptide were only significantly elevated (P < 0.01) among women with cervical invasive carcinoma. Furthermore, there was good agreement between the development of the E6 antibody response and the presence of HPV16 E6 DNA among women with CIN and cervical invasive carcinoma as shown by high values of the kappa coefficient (0.7-1.0). The study clearly revealed a strong agreement between two assay methods defining unambiguous immunogenic B-cell epitopes on synthetic peptides to early and late gene open reading frames of HPV16 which could be used in HPV peptide serology. As such, single or combination of peptides in HPV peptide serology can be used as a screening tool to identify HPV-associated cervical lesions.

Amino Acid Sequence↗
PubMed1996

SCATPLOT: a computer program for determination of binding parameters of non-linear non-cooperative ligand-substrate interactions.

The importance of computer-assisted analysis of a non-linear binding phenomenon through Scatchard equation has been widely acknowledged. While several user-friendly softwares [LIGAND, SCTFIT, ALLFIT] are available for determining the binding parameters of nonlinear Scatchard phenomenon, there is no easily available software covering the class of phenomena described by the McGhee and von Hippel formalism [J. Mol. Biol. 86, 469-489 (1974)]. We report here user-friendly software, SCATPLOT, developed in Turbo BASIC, for the numerical estimation of binding parameters of a non-cooperative ligand-substrate interaction doing best fit to the experimental data on the basis of McGhee and von Hippel equation for a nonlinear Scatchard plot. A new parameter has also been incorporated to guide the process of least square analysis and subsequent determination of binding parameters.

Algorithms↗
PubMed1996

Enhancement of somatic intrachromosomal homologous recombination in Arabidopsis by the HO endonuclease.

The HO endonuclease promotes gene conversion between mating-type alleles in yeast by a DNA double-strand break at the site of conversion (the MAT-Y/Z site). As a first step toward understanding the molecular basis of homologous recombination in higher plants, we demonstrate that expression of HO in Arabidopsis enhances intrachromosomal recombination between inverted repeats of two defective beta-glucuronidase (gus) genes (GUS- test construct). One of these genes has the Y/Z site. The two genes share 2.5 kb of DNA sequence homology around the HO cut site. Somatic recombination between the two repeats was determined by using a histochemical assay of GUS activity. The frequency of Gus+ sectors in leaves of F1 plants from a cross between parents homozygous for the GUS- test construct and HO, respectively, was 10-fold higher than in F1 plants from a cross between the same plant containing the GUS- test construct and a wild-type parent. Polymerase chain reaction analysis showed restoration of the 5' end of the GUS gene in recombinant sectors. The induction of intrachromosomal gene conversion in Arabidopsis by HO reveals the general utility of site-specific DNA endonucleases in producing targeted homologous recombination in plant genomes.

Arabidopsis↗
PubMed1996

A novel cis-acting element is essential for cytokine-mediated transcriptional induction of the serum amyloid A gene in nonhepatic cells.

Serum amyloid A (SAA) is a plasma protein which has been associated with several diseases, including amyloidosis, arthritis, and atherosclerosis, and its abnormal expression, particularly in nonhepatic cells, is implicated in the pathogenesis of these diseases. Transfection and DNA-binding studies were performed to investigate the mechanism controlling cytokine-induced, nonhepatic expression of the SAA gene. We have identified a novel promoter, located between positions -280 and 224, that confers interleukin-6 (IL-6) inducibility to an SAA-chloramphenicol acetyltransferase reporter gene in both nonhepatic and hepatic cells. DNase I protection assays revealed, within this region, three homologous highly pyrimidine rich octanucleotide sequence motifs, termed SAA-activating sequences (SAS). Specific mutations within these three SAS motifs severely reduced IL-6-mediated induction of the reporter gene in transfected nonhepatic cells but not in liver cells. A nuclear factor activated by IL-6 in both hepatic and nonhepatic cells efficiently interacts with the SAS. The induction kinetics and cycloheximide sensitivity of this SAS-binding factor (SAF) suggested that de novo synthesis of this factor itself or an activator protein is essential. Loss of DNA-binding ability as a result of in vitro dephosphorylation, induction of SAA-chloramphenicol acetyltransferase reporter gene activity in the presence of genistein, a protein kinase inhibitor, further indicate that a phosphorylation step is necessary for the activation of SAF. Our results suggest that SAF is a key regulator of cytokine-mediated SAA gene expression in some nonhepatic cells.

Animals↗
PubMed1996

SHORT INTEGUMENT (SIN1), a gene required for ovule development in Arabidopsis, also controls flowering time.

The short integument (sin1) mutation causes a female-specific infertility, and a defect in the control of time to flowering in Arabidopsis. Female sterility of Sin- plants is due to abnormal ovule integument development and aberrant differentiation of the megagametophyte in a subset of ovules. An additional defect of sin1 mutants is the production of an increased number of vegetative leaf and inflorescence primordia leading to delayed flowering. The delayed flowering phenotype of sin1-1 is not due to a defect in the perception of day length periodicity or in gibberellic acid metabolism. Phenotypes of double mutant combinations of sin1 with terminalflower (tfl1) indicate that SIN1 activity is required for precocious floral induction typical in a tfl1 mutant. Unexpectedly, sin1-1 tfl1-1 plants do not make pollen, thus revealing a novel role for TFL1 in the anther. Early flowers of sin1-1 ap1-1 double mutants are transformed to long inflorescence-like shoots. A genetic model for the role of SIN1 in flowering time control is proposed.

Adaptor Protein Complex 1↗
PubMed1996

[15 years survival of the Mac-Kee Farrar metal hip prosthesis. Apropos of 58 cases and 4 explanted cups].

PURPOSE OF THE STUDY: Despite a high percentage of loosening (femoral, iliac or both), many surgeons have been surprised by some excellents results of Mac Kee Farrar prosthesis after 15, or even 20 years follow-up. MATERIALS AND METHODS: 37 patients (on 58) were reviewed with a follow-up of more than 15 years (48 hips). Among 17 cases followed for more than 20 years, with very good results (clinical and radiological), only one femoral loosening was observed. A part, 4 paired explanted implants (loosening at 18 years for 3 and at 21 years for one) were examined for a dimensional and metallurgic study. RESULTS: The results showed: no wear, very good bearing surface statement and sphericity, We never observed agressive granulomatous lesions with metallic particles (metallosis), nor wear concerning the cup. CONCLUSION: The peripheric design appears able to give a very good pressure repartition from cup to bone, allowing a homogeneous coat of cement with an equal thickness, and avoids loosening. Finally, we think that the progressive polar cavity in the cup, could have a great importance on lubrification, as an hydrokinetic reserve and micropump for synovial fluid.

Adult↗
PubMed1996

A comparative evaluation of immunotoxicity of DDT and its metabolites in rats.

Effects of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (DDE), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 2,2-bis(p-chlorophenyl) acetic acid (DDA) were comparatively evaluated on humoral and cell mediated immune (CMI) responses in rats. Rats were given a diet containing 200 ppm of the various test compounds for 6 weeks and were subsequently immunized with ovalbumin. DDT, DDE and DDD, all induced differential degrees of humoral and cellular immune suppression. There were (a) increases in albumin/globulin ratios, (b) suppression of IgM and IgG levels, and (c) attenuations in ovalbumin induced antibody responses. In CMI studies, there were marked inhibitions of (a) leucocyte and macrophage migration factors, and (b) delayed type hypersensitivity (DTH) reaction. Whereas, these effects were most marked with DDE and DDD, DDA did not elicit such immunomodulatory effects. It is inferred that suppression of immune responses by immediate DDT metabolites, DDE (and DDD and not DDA) is an important determinant of the toxicity of DDT (DDE > DDD > DDT) and the influence of this environmental pollutant in health and disease.

Animals↗
PubMed1996

Bioenergetic effects of repeated +Gz acceleration on rat heart: a 31P-NMR study on isolated hearts.

This investigation was designed to determine whether repeated exposure to high sustained +Gz acceleration induces persisting changes in the myocardial energetic metabolism. Rats were exposed to three plateaus of 30 s at 10 +Gz, four times a week, for 4 weeks. Myocardial concentrations of high-energy phosphorylated compounds were evaluated by 31P-nuclear magnetic resonance (NMR) spectroscopy on isolated hearts submitted to isovolumic aortic perfusion. Heart performances were recorded using the intraventricular balloon method. Compared to the hearts of control rats (n = 5), the hearts of centrifuged rats (n = 5) had higher concentrations of inorganic phosphate (Pi:1.40 +/- 0.33 nM vs. 0.36 +/- 0.07 mM; p < 0.01), decreased phosphocreatine concentrations (PC:15 +/- 0.39 mM vs. 15.69 +/- 0.19 mM; p < 0.01), and a lower left ventricular developed pressure (LVDP) (21 +/- 1 mmHg vs. 34 +/- 2 mmHg; p < 0.01). The workload was increased by sequential augmentation of calcium in the perfusion medium. The relationship between LVDP and the Pi/PC ratio showed that the cost of the cardiac work was greater for the centrifuged rats.

Animals↗