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Biomedical subjects

M Royer

Publications and source records attributed to M Royer.

At least 19 recordsLinked to original sources
PubMed2006

Yellow leaf of sugarcane is caused by at least three different genotypes of sugarcane yellow leaf virus, one of which predominates on the Island of Réunion.

The genetic diversity of sugarcane yellow leaf virus (SCYLV) was analyzed with 43 virus isolates from Réunion Island and 17 isolates from world-wide locations. We attempted to amplify by reverse-transcription polymerase chain reaction (RT-PCR), clone, and sequence four different fragments covering 72% of the genome of these virus isolates. The number of amplified isolates and useful sequence information varied according to each fragment, whereas an amplicon was obtained with diagnostic primers for 59 out of 60 isolates (98%). Phylogenetic analyses of the sequences determined here and additional sequences of 11 other SCYLV isolates available from GenBank showed that SCYLV isolates were distributed in different phylogenetic groups or belonged to single genotypes. The majority of isolates from Réunion Island were grouped in phylogenetic clusters that did not contain any isolates from other origins. The complete six ORFs (5612 bp) of five SCYLV isolates (two from Réunion Island, one from Brazil, one from China, and one from Peru) were amplified, cloned, and sequenced. The existence of at least three distinct genotypes of SCYLV was shown by phylogenetic analysis of the sequences of these isolates and additional published sequences of three SCYLV isolates (GenBank accessions). The biological significance of these genotypes and of the origin of the distinct lineage of SCYLV in Réunion Island remains to be determined.

Cloning, Molecular↗
PubMed2006

Metabolic syndrome throughout the menopausal transition: influence of age and menopausal status.

OBJECTIVE: To assess the relationship between the main components of both the metabolic syndrome and insulin resistance and menopausal status in the menopausal transition. METHODS: A total of 124 healthy women were divided into four groups according to their menstrual status: the first group consisted of 35 women in menopausal transition with menstrual bleeding (MTM) and with cycles between 35 and 80 days; the second group was composed of 29 women in menopausal transition with 3-6 months of amenorrhea (MTA). The third group consisted of 31 postmenopausal women (PostM) and the fourth group of 29 premenopausal women (PreM) with regular cycles. The metabolic syndrome was evaluated following the ATP III criteria. Evaluation of insulin resistance was made through the HOMA, QUICKI and McAuley indices and the triglycerides/high density lipoprotein (HDL) cholesterol ratio. RESULTS: The triglycerides/HDL cholesterol ratio increased in MTM, MTA and PostM women in comparison with PreM women. A slight decrease in the QUIKI index (p = 0.06) and a decrease in the McAuley index (p < 0.001) were observed in MTM, MTA and PostM women in comparison to PreM women. The relative frequencies of metabolic syndrome in the four groups were: PreM, 0%; MTM, 20%; MTA, 21%; and PostM, 22% (p = 0.0001). The most frequent markers of the metabolic syndrome were increased waist circumference, low HDL cholesterol levels and hypertension. Linear regression between menopausal status and metabolic syndrome was lost when age was added to the model. CONCLUSIONS: The frequency of metabolic syndrome increased from the time of the menopausal transition to the postmenopause. Abdominal obesity was the most frequent feature observed. Nevertheless, aging erased the effect of the menopause on the metabolic syndrome. In order to prevent cardiovascular disease, the metabolic syndrome must be evaluated from the time of the menopausal transition.

Adult↗
PubMed2004

Lipid and lipoprotein profile in menopausal transition. Effects of hormones, age and fat distribution.

The behavior of lipoproteins during the menopausal transition and their relationship with sex hormones and body fat distribution is still unclear. Our aim was to evaluate atherogenic IDL, LDL, Lp(a) and antiatherogenic HDL lipoproteins in four groups of women: premenopausal (n = 20), menopausal transition women with menstrual bleeding (n = 31), menopausal transition women with 3 to 6 months amenorrhea (n = 36), and postmenopausal women (n = 30). We also measured their FSH, LH and estradiol levels along with BMI and waist circumference. Menopausal transition and postmenopausal women showed higher values of waist circumference (p < 0.0032), LDL-cholesterol (p < 0.002), IDL-cholesterol (p < 0.002) and apoprotein B (p < 0.0001) than premenopausal women. Total-cholesterol (p < 0.0001), triglycerides (p < 0.004), IDL-cholesterol and Lp(a) were higher in menopausal transition women with amenorrhea and in postmenopausal women in comparison with premenopausal women. After adjustment according to age and waist circumference, multiple regression analysis showed the increase in total-cholesterol and LDL-cholesterol to be linearly associated to menopausal status and estradiol concentration, whereas Lp(a) was only related to menopausal status. Age was found to be an independent variable in relation to apoprotein B concentration changes. The effect of menopausal status on TG levels did not remain in the model when age, waist and BMI were included (beta = 0.05, p = 0.356). HDL-cholesterol levels were the same in all the groups. Menopause, age and the increase in abdominal fat distribution were three independent and significant factors impairing lipoprotein profiles from the beginning of the menopausal transition.

Adipose Tissue↗
PubMed2004

Low levels of endogenous estradiol protect bone mineral density in young postmenopausal women.

OBJECTIVE: Low levels of endogenous estrogens may play a role in the protection of bone mineral density (BMD) in healthy postmenopausal women. The aim of this study was to evaluate the effect of endogenous estradiol and testosterone on bone mass in young and older healthy postmenopausal women. METHODS: The study involved 99 postmenopausal women aged 55-75 years. The BMDs of the lumbar spine, proximal femur and total skeleton were determined. Measurements were taken of serum calcium, bone alkaline phosphatase, Crosslaps, estradiol, estrone, sex hormone binding globulin, testosterone, bioavailable testosterone and urine calcium. Estradiol was measured using a sensitive assay with a lower detection limit at 5 pg/ml. RESULTS: A multivariate analysis showed that the BMD of the lumbar spine was significantly predicted by estradiol (p < 0.05), and testosterone (p < 0.0001). Likewise, testosterone was found to be an independent predictor of the BMD of the total femur (p < 0.001) and the total skeleton (p < 0.001). The population was divided into two groups: < or = 65 (Group 1) and > 65 years (Group 2) of age and also stratified according to estradiol levels: > 10 and < or = 10 pg/ml. Significant differences in BMD were found in women in Group 1 in whom estradiol levels higher than 10 pg/ml were associated with a higher BMD of the lumbar spine (+ 14%, p < 0.01), proximal femur (+ 6%, p < 0.05) and total skeleton (+ 7%, p < 0.05) compared with women with estradiol levels below 10 pg/ml. Bone alkaline phosphatase levels (p < 0.05) and serum Crosslaps (not significant) were lower in women in Group 1 with a level of estradiol more than 10 pg/ ml. CONCLUSION: Endogenous estradiol levels higher than 10 pg/ml and testosterone protected bone mass in healthy postmenopausal women under 65 years of age. These results were not observed in the group of older women.

Age Factors↗
PubMed2003

Genetic diversity in the coat protein coding region of eighty-six sugarcane mosaic virus isolates from eight countries, particularly from Cameroon and Congo.

Fifty-eight sugarcane virus isolates were obtained from leaves showing mosaic symptoms, and collected in Cameroon (26 isolates), Congo (20 isolates), Egypt (1 isolate), South Africa (3 isolates) and the U.S.A. (8 isolates). All these isolates belonged to Sugarcane mosaic virus (SCMV) based on the amplification product obtained by RT-PCR with SCMV-specific primers. The amplicons (0.9 kb) from the coat protein (CP) coding region were cloned, sequenced and compared to each other as well as to the sequences (GenBank accessions) of 16 SCMV isolates from sugarcane (Australia, South Africa and U.S.A.) and 12 SCMV isolates from maize (Australia, Germany and China). Maximum likelihood and maximum parsimony analyses robustly supported two major monophyletic groups that were correlated with the host of origin: the SCE or sugarcane group that included all isolates from sugarcane and the MZ or maize group that contained all isolates from maize. The 86 virus isolates were distributed in 13 minor phylogenetic groups, four (I-IV) restricted to maize and nine (V-XIII) to sugarcane. A strong correlation was observed between the sugarcane groups and the geographical origin of the SCMV isolates. Each SCMV type strain from sugarcane (A, B, D, E and SC) was distributed in a different phylogenetic group or subgroup. The 26 isolates from Cameroon constituted a relatively homogeneous group (group V) whereas the 20 isolates from Congo belonged to two other groups (VI and VII). All the isolates from Cameroon and Congo were different from the SCMV type strains and other strains or isolates studied so far. It appears, therefore, that the population of SCMV from sugarcane in Africa contains virus genotypes that have not yet been described.

Cameroon↗
PubMed2001

Role of interdomain salt bridges in the pore-forming ability of the Bacillus thuringiensis toxins Cry1Aa and Cry1Ac.

The four salt bridges (Asp(222)-Arg(281), Arg(233)-Glu(288), Arg(234)-Glu(274), and Asp(242)-Arg(265)) linking domains I and II in Cry1Aa were abolished individually in alpha-helix 7 mutants D222A, R233A, R234A, and D242A. Two additional mutants targeting the fourth salt bridge (R265A) and the double mutant (D242A/R265A) were rapidly degraded during trypsin activation. Mutations were also introduced in the corresponding Cry1Ac salt bridge (D242E, D242K, D242N, and D242P), but only D242N and D242P could be produced. All toxins tested, except D242A, were shown by light-scattering experiments to permeabilize Manduca sexta larval midgut brush border membrane vesicles. The three active Cry1Aa mutants at pH 10.5, as well as D222A at pH 7.5, demonstrated a faster rate of pore formation than Cry1Aa, suggesting that increases in molecular flexibility due to the removal of a salt bridge facilitated toxin insertion into the membrane. However, all mutants were considerably less toxic to M. sexta larvae than to the respective parental toxins, suggesting that increased flexibility made the toxins more susceptible to proteolysis in the insect midgut. Interdomain salt bridges, especially the Asp(242)-Arg(265) bridge, therefore contribute greatly to the stability of the protein in the larval midgut, whereas their role in intrinsic pore-forming ability is relatively less important.

Animals↗
PubMed2001

Mucoepidermoid carcinoma of the thyroid gland: a case report and suggested surgical approach.

Mucoepidermoid carcinoma (MEC) of the thyroid gland is a rare neoplasm with 40 cases reported in the world literature to date. Controversy surrounds the treatment of this rare neoplasm. It has been described as a low-grade indolent tumor that rarely metastasizes and only recurs locally without morbidity. Suggested treatment has consisted of a lobectomy or subtotal thyroidectomy. We report a case of a 63-year-old woman with a 15-year history of a multinodular goiter with a dominant left lobe nodule. Fine-needle aspiration was inconclusive. The patient opted for a total thyroidectomy. Final pathology yielded a diagnosis of mucoepidermoid carcinoma. We propose that despite its low-grade appearance the morbidity and mortality associated with its ability to locally recur and metastasize justify the need for more aggressive surgical therapy.

Carcinoma, Mucoepidermoid↗
PubMed2001

[Profile of antimicrobial resistance of agents causing urinary tract infections in Chilean children. PRONARES surveillance program].

BACKGROUND: PRONARES (Programa Nacional de Vigilancia de Resistencia) is a national surveillance program for antimicrobial susceptibility, focused in different syndromes and among these, urinary tract infections. The work is done in a laboratory net that uses common protocols and whose data are centrally analyzed using the WHONET program. AIM: To analyze the pattern of antimicrobial susceptibility of agents causing urinary infections in children in the period 1997-1999. MATERIAL AND METHODS: In the study period, 5,525 strains were analyzed. Of these, 2,307 came from pediatric patients (1,495 hospitalized and 803 ambulatory). RESULTS: The most common causative agent was E. coli in 74.2% of cases, followed by Klebsiella spp in 8.2% and other agents in a lower frequency. Of E. coli strains, 74% were resistant to ampicillin, 52% to clotrimoxazole and 30% to first generation cephalosporins. These strains were sensitive to second and third generation cephalosporins, aminoglycosides, ciprofloxacin and nitrofurantoin. Strains from nosocomial or community infections had similar antimicrobial susceptibility. Klebsiella spp had a high rate of antimicrobial resistance (over 40%), that was even higher among nosocomial strains. It was 90% susceptible to ciprofloxacin and 100% to imipenem. All centers from which strains came had a similar pattern of susceptibility, with the exception of a pediatric center that had significantly higher resistance levels. CONCLUSIONS: The current therapeutic recommendations for urinary tract infections in children caused by E coli, are still pertinent, but the use of first generation cephalosporins must be cautious. The treatment of Klebsiella spp requires an individual antibiogram.

Adolescent↗
PubMed2000

Identification of species and sources of Cryptosporidium oocysts in storm waters with a small-subunit rRNA-based diagnostic and genotyping tool.

The identification of Cryptosporidium oocysts in environmental samples is largely made by the use of an immunofluorescent assay. In this study, we have used a small-subunit rRNA-based PCR-restriction fragment length polymorphism technique to identify species and sources of Cryptosporidium oocysts present in 29 storm water samples collected from a stream in New York. A total of 12 genotypes were found in 27 positive samples; for 4 the species and probable origins were identified by sequence analysis, whereas the rest represent new genotypes from wildlife. Thus, this technique provides an alternative method for the detection and differentiation of Cryptosporidium parasites in environmental samples.

Animals↗
PubMed1999

Expression of orf1 from the Bacillus thuringiensis NRD-12 cry2Aa1 operon.

The 5' untranslated region and the orf1 sequence from the cry2Aa1 operon from Bacillus thuringiensis subsp. kurstaki NRD-12 were sequenced and compared to that from strain HD-1. The start codon described in HD-1 does not yield in NRD-12 a protein of the expected size of 20 kDa, but a 10-amino acid peptide. A second, highly conserved start codon is located 25 bp downstream from the first one and corresponds to an open reading frame of the same size in all known orf1-related sequences. Expression of lacZ gene fusions created at the level of the first ATG, second ATG, and stop codon of the NRD-12 orf1 sequence showed that orf1 is translated from the second ATG. The expected protein is 19 kDa in size. The expression starts at t2, which is in agreement with the presence of a BtI promoter in the cry2Aa1 operon.

Amino Acid Sequence↗
PubMed1999

Is cognitive impairment a guide to use of Video Respite? Lessons from a special care unit.

The goal of this study was to examine the usefulness of Video Respite (VR) in relation to the abilities of cognitively impaired older adults. Three VR videotapes were shown to residents of a special care unit. Older adults were videotaped as they viewed the VR videotapes to observe their levels of involvement. Analyses of the videotapes of the older adults confirmed that participation varies considerably between and within residents and, further, that cognitive status is not a useful guide in predicting levels of participation. Some residents showed no interest in television in general or in VR, while the elimination of distractions resulted in more sustained viewing for those inclined to participate. The authors' observations suggest ways to optimize the usefulness of VR for formal and informal caregivers.

Aged↗
PubMed1998

Related alphaN- and epsilonN-methyltransferases methylate the large and small subunits of Rubisco.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is methylated at the ax amino position of the N-terminal methionyl residue of the processed and assembled form of the small subunit (SS), and is also methylated in some species at the epsilon-amino group of lysine-14 in the large subunit (LS). The gene (rbcMT-S) and cDNAs for the SS alphaN-methyltransferase (SSMT) from spinach (Spinach oleracea) have been cloned, sequenced, and expressed. The gene is closely related to a previously characterized LS methyltransferase (Rubisco LSMT) cDNA from pea (Rubisco LSMT) and a Rubisco LSMT gene from tobacco. Sequence analysis of the cDNA and transcript mapping experiments demonstrate that the rbcMT-S pre-mRNAs experience alternative 3' splice site selection, such that mRNAs for a long form with a four amino acid insertion and a short form are expressed at approximately equal abundance. The coding sequence of spinach SSMT includes a putative targeting presequence with sequence identity at a plastid processing site. A N-terminal truncated form of spinach SSMT was expressed and purified from E. coli cells. Both long and short forms of the cDNAs were shown to catalyze methylation of the a amine of the N-terminal methionine of the SS of Rubisco.

Alternative Splicing↗
PubMed1997

Proteolytic activity in vivo and encapsidation of recombinant human immunodeficiency virus type 1 proteinase expressed in baculovirus-infected cells.

The activity in vivo of HIV-1 proteinase (PR) was analysed in the baculovirus expression system, using eight different constructs of the prt gene under the control of polyhedrin (PH) promoters of various strengths. None of the active PRs was expressed in substantial quantities, and only PH-fused and/or non-functional PR mutants accumulated in high amounts in insect cells. However, enough PR activity was generated from a lengthened PR construct in insect cells to process Gag polyprotein substrate co-expressed in the same cells in trans. Fusion of the first 58 residues from the PH sequence to the PR N terminus did not significantly change its activity and specificity of cleavage of the Gag substrate. When analysed under mild denaturing conditions, PH-fused or unfused full-length PR point mutants, as well as PH-fused or unfused C-terminal deletion mutants, showed a propensity to multimerize, with a predominant occurrence of dimers. The incorporation of PR into Gag particles was studied using eight Gag-PR fusion constructs, all containing a non-functional PR mutant. The PR domain was fused to the C-terminal p6 domain of Gag (p6gag), or translated in frame with NCp7 (as in frameshifted Gag-Pol polyprotein) and followed by downstream sequences of increasing lengths from the Pol domain or the bacterial beta-galactosidase. The results suggested that the presence of the p6gag domain was detrimental to the encapsidation of polyprotein-embedded PR.

Animals↗
PubMed1995

Affinity purification of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit epsilon N-methyltransferase.

Ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit epsilon N-methyltransferase (Protein methylase III, Rubisco LSMT, EC 2.1.1.43) catalyzes methylation of the epsilon-amino group of Lys-14 in the large subunit of Rubisco. In this paper, an affinity purification procedure for pea (Pisum sativum L. cv Laxton's Progress No. 9) Rubisco LSMT is described and characterized. Spinach (Spinacia oleracea L. cv Melody) Rubisco, a substrate for pea Rubisco LSMT, was immobilized to polyvinylidene fluoride (PVDF) transfer membranes (Immobilon-P) and used as a ligand for the affinity purification of Rubisco LSMT from pea leaf extracts and chloroplast lysates. Pea Rubisco LSMT specifically bound to PVDF-immobilized spinach Rubisco but not to control PVDF membranes which contained immobilized BSA or pea Rubisco. Rubisco LSMT was not eluted by 1 M KCl but was specifically released by S-adenosyl-L-methionine (AdoMet) or spinach Rubisco. Elution of Rubisco LSMT by AdoMet was a result of catalytic methylation of the PVDF-immobilized spinach Rubisco, and was therefore more efficient than elution by the competitive ligand spinach Rubisco. An increase in the specific activity of Rubisco LSMT of approximately 7000-fold was achieved in one step with this affinity purification technique. Rubisco LSMT is a monomeric protein with a molecular mass of approximately 60 kDa.

Chromatography, Affinity↗
PubMed1992

Expression and extracellular release of human immunodeficiency virus type 1 Gag precursors by recombinant baculovirus-infected cells.

The level of synthesis and extracellular release of human immunodeficiency virus type 1 Gag by insect cells was analyzed, using eight different recombinants of Autographa californica nuclear polyhedrosis virus harboring various constructs of the gag gene, cloned under the polyhedrin promoter. The results obtained suggested that gag expression was mainly regulated at the transcriptional level and was not significantly influenced by posttranslational events, e.g., Gag self-assembly, nuclear transport, or extracellular release. Two different forms of Gag were found in the culture medium of recombinant-infected cells. One form consisted of membrane-enveloped, corelike particles released by budding at the plasma membrane; the other of nonparticulate, soluble Gag polyprotein molecules. Both forms coexisted in recombinants expressing Gag with an intact N-terminal myristylation signal, whereas recombinants expressing nonmyristylated Gag released solely the soluble form. This suggested that myristylation of the N terminus was not a prerequisite for efficient extracellular release of Gag by insect cells, which could proceed via two independent but simultaneous mechanisms.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Cholinergic inositol phosphate formation in striatal neurons is mediated by distinct mechanisms.

In murine striatal neurons devoid of functional synapses (6 days in vitro) the cholinergic agonists carbachol and arecoline evoked dose-dependent inositol phosphate (InsP) responses with mean log EC50s of -4.1 +/- 0.5 and -4.48 +/- 0.1, respectively. Carbachol (1 mM) and arecoline (1 mM) responses were insensitive to tetrodotoxin, a voltage-sensitive Na+ channel blocker, and were blocked by pirenzepine with relatively low affinity (logIC50 = -5.9 +/- 0.3 for the carbachol response and logIC50 = -5.8 +/- 0.3 for the arecoline response). After synaptogenesis (13 days in vitro) the maximal carbachol effect doubled whereas the arecoline response remained unchanged. This additional effect was sensitive to tetrodotoxin and the voltage-dependent Ca2+ channel blocker, omega-conotoxin. The tetrodotoxin-sensitive carbachol response was blocked by lower concentrations of pirenzepine than the tetrodotoxin-insensitive carbachol response. More than 75% of the InsP response evoked by low concentrations of muscarine (1 and 10 microM) was sensitive to tetrodotoxin whereas only 38% of the InsP response stimulated by 1 mM of muscarine could be blocked by tetrodotoxin. These results suggest that there are at least two different mechanisms (depending on the stage of development), activated most probably by two different muscarinic receptors responsible for the carbachol-induced InsP formation in striatal neurons.

Animals↗
PubMed1991

Functional domains of HIV-1 gag-polyprotein expressed in baculovirus-infected cells.

Seven recombinants of AcNPV harboring various forms of complete or truncated gag gene from HIV-1 were constructed to determine which functional domains of the gag polyprotein are implicated in its self-assembly and cellular localization. The p6 carboxy-terminal portion of the p15 NCgag domain appeared to be dispensable for assembly, budding, and release of gag particles by insect cells. However, all the morphopoietic information was not entirely confined to the p9 NC domain, as N-myristylation could compensate for p15 NC deletion in gag assembly and the budding process. The two consensus karyophilic signals situated in the p17 MAgag domain were inefficient for targeting nonmyristylated forms of gag polyprotein to the nucleus when the p6 NC domain was deleted. In the presence of p6, or with a third, baculovirus-specific, karyophilic signal added at its N-terminus, gag particles relocated in the nucleus. These data suggested that p6 played a critical role in the conformation of gag polyprotein.

Amino Acid Sequence↗