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A Marais

Publications and source records attributed to A Marais.

At least 19 recordsLinked to original sources
PubMed2006

Asian prunus viruses: New related members of the family Flexiviridae in Prunus germplasm of Asian origin.

Serological reactivity to Plum pox virus (PPV) antisera has been described in several Prunus sources of Asian origin that are free of PPV infection. Using polyvalent or specific PCR assays, the presence of three closely related agents in two of these sources, Prunus mume cv. Bungo and P. persica cv. Ku Chu'a Hung, was demonstrated. Similarities in genome organization and sequence comparisons indicate that these agents should be regarded as members of the genus Foveavirus, their only singular trait being a very large (>800 nt) 3' non-coding region (NCR), as compared to the ca. 130-180 nt 3' NCR observed in other Foveaviruses. The three agents are very divergent from known Foveaviruses but are also significantly removed one from the others, with overall nucleotide sequence identity levels in the sequenced region of ca. 74-76% and of only 60.8-67.5% in their complete CP gene (61.9-71.3% amino acid sequence identity). Given the species discrimination criteria in the family Flexiviridae, these three agents should be regarded as three related yet distinct new viruses belonging to the Foveavirus genus, for which the names Asian prunus virus 1, 2 and 3 are proposed. Evidence is provided for the presence of variants of these new viruses in other Prunus germplasm of Asian origin.

Amino Acid Sequence↗
PubMed2005

Molecular characterization of banana virus X (BVX), a novel member of the Flexiviridae family.

A novel virus was identified in banana (Musa spp). Analysis of the last 2917 nucleotides of its positive strand genomic RNA showed five open reading frames corresponding, from 5' to 3', to a truncated ORF coding for a replication-associated protein, three ORFs coding for a movement-associated triple gene block (TGB) and a capsid protein (CP) gene. This genome organization is similar to that of some members of the Flexiviridae family such as potexviruses and foveaviruses. This virus was named Banana virus X (BVX). Comparative sequence analysis showed that BVX is only distantly related to other members of the Flexiviridae family, in which it appears to define a new genus. BVX produces defective RNAs derived from its genomic RNA by non-homologous recombination. Three distinct pairs of donor/acceptor recombination sites involving short direct nucleotide repeats were characterized, accounting for deletions of 1268, 1358 and 1503 nucleotides. Contrary to the situation encountered for Potexviruses, these recombination sites are located within the TGB1 and CP genes and result in a truncated TGB1 protein.

Capsid Proteins↗
PubMed2001

Mediation of elicitin activity on tobacco is assumed by elicitin-sterol complexes.

Elicitins secreted by phytopathogenic Phytophthora spp. are proteinaceous elicitors of plant defense mechanisms and were demonstrated to load, carry, and transfer sterols between membranes. The link between elicitor and sterol-loading properties was assessed with the use of site-directed mutagenesis of the 47 and 87 cryptogein tyrosine residues, postulated to be involved in sterol binding. Mutated cryptogeins were tested for their ability to load sterols, bind to plasma membrane putative receptors, and trigger biological responses. For each mutated elicitin, the chemical characterization of the corresponding complexes with stigmasterol (1:1 stoichiometry) demonstrated their full functionality. However, these proteins were strongly altered in their sterol-loading efficiency, specific binding to high-affinity sites, and activities on tobacco cells. Ligand replacement experiments strongly suggest that the formation of a sterol-elicitin complex is a requisite step before elicitins fasten to specific binding sites. This was confirmed with the use of two sterol-preloaded elicitins. Both more rapidly displaced labeled cryptogein from its specific binding sites than the unloaded proteins. Moreover, the binding kinetics of elicitins are related to their biological effects, which constitutes the first evidence that binding sites could be the biological receptors. The first event involved in elicitin-mediated cell responses is proposed to be the protein loading with a sterol molecule.

Algal Proteins↗
PubMed2001

Composition and gene expression of the cag pathogenicity island in Helicobacter pylori strains isolated from gastric carcinoma and gastritis patients in Costa Rica.

The composition and in vitro expression of the cag pathogenicity island genes in a group of Helicobacter pylori strains obtained from patients suffering from chronic gastritis-associated dyspepsia (n = 26) or gastric carcinoma (n = 17) were analyzed. No significant difference in the distribution of the 10 studied regions was found between the cases and the controls. Nine strains did not harbor any of the selected regions: eight (30.8%) isolated from patients with gastritis only and one (5.9%) from a patient with gastric carcinoma. No association was found between the number of repeated sequences at the 3' end of the cagA gene or the presence of tyrosine phosphorylation motifs and the clinical origin of the strains. The virB10 homolog gene was the sole gene studied to be significantly expressed more often in cancer strains than in gastritis strains (P = 0.03).

Antigens, Bacterial↗
PubMed2001

cagA Status and eradication treatment outcome of anti-Helicobacter pylori triple therapies in patients with nonulcer dyspepsia.

The differences in eradication rates reported in clinical trials aiming to cure Helicobacter pylori infection cannot be entirely explained by the type of regimen, bacterial resistance, or lack of compliance. Using data from a clinical trial, a logistic regression model was constructed to determine whether cagA status, assessed by PCR, affects the outcome of eradication. Resistance to clarithromycin (10% of the strains) predicted failure perfectly. In the model (n = 156), a cagA-lacking strain (odds ratio [OR] = 2.2; 95% confidence interval [CI], (1.1 to 4.7), tobacco smoking OR = 3.1; 95% CI, 1.3 to 7.0), and a double dose of proton pump inhibitor in the treatment regimen (OR = 0.3; 95% CI, 0.2 to 0.7) were associated with the treatment outcome. The exact role of cagA in the outcome of H. pylori eradication therapy has not been explored. However, the type of histological lesions which it causes in the gastric mucosa may be implicated. Regardless of the mechanism involved, cagA status is a good predictive marker of eradication outcome.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

Detection of Helicobacter species in the liver of patients with and without primary liver carcinoma.

BACKGROUND: Several studies have shown the presence of Helicobacter species in the human biliary tract and in the intestinal tract of animals. In this study, the presence of Helicobacter species in liver samples from patients with primary hepatic carcinomas was evaluated. METHODS: Sixteen liver specimens were studied (8 from patients with primary liver carcinoma and 8 from patients without primary liver carcinoma). Histology with standard stains, culture, and polymerase chain reaction (PCR) amplification using two sets of primers located in the 16S ribosomal DNA (rDNA) were used to detect the presence of bacteria. Amplified products were sequenced to determine the genus and species of the bacteria. A search for other genes that were specific for Helicobacter pylori also was carried out by PCR. RESULTS: PCR performed with the 16S rDNA primers revealed the presence of bacteria from the genus Helicobacter in all of the liver specimens from patients with primary liver carcinoma (eight of eight patients) and in one specimen from a patient without primary liver carcinoma (one of eight patients). When the nucleotide sequence of > 80% of the 16S rDNA was determined, the closest similarity was with the 16S rDNA from H. pylori in eight patients. In 1 patient sample from which only 398 nucleotides were sequenced, the closest match was Helicobacter felis. CONCLUSIONS: The results presented in this study indicate that Helicobacter species can be present in the liver of patients with primary hepatic carcinoma, but their eventual role in the carcinogenesis process, although it is plausible, remains to be proven. Based on sequence similarity, it seems that Helicobacter species that are related closely to H. pylori but are distinct from it have been found.

Adult↗
PubMed2000

Helicobacter cinaedi septic arthritis and bacteremia in an immunocompetent patient.

We report on the first case of documented Helicobacter cinaedi septic arthritis in an immunocompetent heterosexual young man. The patient presented no identified risk factor except for contact with animals that have been incriminated as a possible source of infection, particularly for these patients. Despite prolonged bacteremia, the response to long-term therapy with ciprofloxacin and rifampin was excellent.

Adult↗
PubMed2000

Distribution of open reading frames of plasticity region of strain J99 in Helicobacter pylori strains isolated from gastric carcinoma and gastritis patients in Costa Rica.

The plasticity region of Helicobacter pylori strain J99 is a large chromosomal segment containing 33 strain-specific open reading frames (ORFs) with characteristics of a pathogenicity island. To study the diversity of the plasticity region, 22 probes corresponding to 20 ORFs inside the plasticity region and two ORFs on its boundaries were hybridized to genomic DNA isolated from clinical strains of H. pylori from patients with gastritis or gastric adenocarcinoma. Highly variable hybridization patterns were observed. The majority of the clinical strains presented a hybridization profile similar to that of J99; thus, these ORFs are not J99 strain specific. No association was found between a particular hybridization pattern and the clinical origin of the strain. Nevertheless, two single ORFs (JHP940 and JHP947) were more likely to be found in gastric cancer strains. They may be new pathogenicity markers. An in vitro expression study of these ORFs was also performed for the J99 strain, under different conditions. Thirteen ORFs were consistently expressed, six were consistently shut off, and three were expressed differentially. Most of the constitutionally expressed genes were located on the 3' part of the plasticity region. Our results show that the plasticity region, rather than being considered a pathogenicity island per se, should be considered a genomic island, which represents a large fragment of foreign DNA integrated into the genome and not necessarily implicated in the pathogenic capacity of the strain.

Blotting, Southern↗
PubMed2000

[Prevalence of hepatitis A, B, C virus markers in Réunion (south hospital and Saint Pierre prison)].

We studied the prevalence of Hepatitis A, B, C in different groups in the population of the South of Reunion Island. The aims of this study were the following: to estimate the prevalence of Hepatitis C virus (HCV) (anti-HCV antibodies) and Hepatitis B virus (HBV) (anti-HBc, HBs Ag and anti-HBs) in a population of 1455 women, who delivered in the Centre hospitalier Sud Reunion (CHSR), to estimate the prevalence of these two viruses in a population selected for risk factors (100 prisoners), to estimate the prevalence of Hepatitis A in a group of 400 persons (aged 0 to 19) hospitalised in CHSR since 1st January 1998 (100 for each 5-year age bracket), to research risks factors in these populations and immunity. The overall prevalence of anti-HCV was 0.14% in pregnant women and risk factor associated was found in 28.9% of this population (2.9% history of transfusion, 0.21% drug users). In the group of prisoners seroprevalence was 2%, far below that of prisoners in France. Anti-HCV seroprevalence is weak in Reunion Island and very inferior to seroprevalence in the French population as in other Indian Ocean islands. This is due to the low risk of parenteral transmission. Anti-HBc was found in 90 serum samples from women (overall prevalence 6.35%) and of these 90 positive samples, 9 were positive for HBs Ag (overall prevalence 0.63%), 68 were positive for anti-HBs (4.81%) and 22 (1.54%) were anti-HBc isolated (without HBs Ag and anti-HBs). The overall prevalence of anti-HBs was 62.8%. In the population of 100 prisoners, 2 were HBs Ag positive, 10 anti-HBc positive (2 anti-HBc isolated, 2 associated with HBs Ag, 6 with anti-HBs). The prevalence of anti-HBs was 22%. The major risk factor observed in this population of prisoners was tattooing and/or piercing (46%). These results show that: Reunion island is an area of low endemicity for HBV virus. The measure of protective inoculation is well followed. i.v. drug abuse and previous transfusion are weak routes of transmission. In the group aged 0 to 19, overall prevalence of anti-HAV was 11.9% with the highest rate found among 15 to 19 year-olds (25%). Seroprevalence falls with socio-economic progress. At the present time, the endemic is intermediate in Reunion Island. Given immunity levels within the young population, there is a risk of outbreak. This risk is due to the conditions in Reunion Island, but also to people who travel to other Indian Ocean countries where endemicity is high. It is thus very important that a vaccination strategy be determined.

Adolescent↗
PubMed1999

Rapid detection, by PCR and reverse hybridization, of mutations in the Helicobacter pylori 23S rRNA gene, associated with macrolide resistance.

A PCR-based reverse hybridization system (research prototype kit INNO-LiPA for H. pylori resistance) was developed and evaluated for simultaneous detection of 23S ribosomal DNA point mutations, associated with macrolide resistance in Helicobacter pylori. Fifty-seven H. pylori strains (51 natural, 6 laboratory-derived artificial, 52 resistant, and 5 susceptible strains) were tested by PCR-LiPA (detecting mutations A2115-->G, G2141-->A, A2142-->G, A2142-->C, A2143-->G, A2143-->C, and A2143-->T), DNA sequencing, restriction fragment length polymorphism, and/or hybridization to oligonucleotide probes. Results were highly concordant, but PCR-LiPA appears to be more sensitive for the simultaneous detection of multiple mutants.

Anti-Bacterial Agents↗
PubMed1999

Helicobacter species colonizing pig stomach: molecular characterization and determination of prevalence.

The infection rate of 60 pigs (10 pigs from each of six farms) by Helicobacter species was studied by two techniques. Histological examination of the cardiac area of the stomach yielded a 58% positive result versus an 80% positive result by PCR with genus-specific primers. Eighty percent of the 16S rRNA gene was amplified, classified in four groups by PCR-restriction fragment length polymorphism, and sequenced. Isolates from all farms except one (farm C) were identified as Helicobacter heilmannii type 1, while those from farm C were identified as H. heilmannii type 2. Attempts to culture this organism in vitro failed. Helicobacter pylori was not found in these animals.

Animals↗
PubMed1999

Human embryonic gastric xenografts in nude mice: a new model of Helicobacter pylori infection.

In vitro or animal models have been used to investigate the pathogenesis of Helicobacter pylori infection. However, extrapolation to humans of results obtained with these heterologous models remains difficult. We have developed a new model for the study of H. pylori infection that uses human entire embryonic stomachs engrafted in nude mice. At 80 days after implantation, 22 of these xenografts, which exhibited a mature gastric epithelium, were inoculated with 10(7) to 10(8) CFU of either H. pylori LB1, a freshly isolated H. pylori strain (n = 12), or H. pylori ATCC 49503 (n = 10). After 12-week examination, H. pylori LB1 persistently colonized the antrum of all inoculated grafts, as assessed by culture (mucus and mucosa), immunohistochemistry (mucosa), and a rapid urease test (mucus). H. pylori ATCC 49503, either before or after in vivo passage, permitted only a transient 2-week colonization in one of the five inoculated grafts in both groups. Colonization was always associated with an increase of gastric juice pH. A mild neutrophil infiltration of the gastric mucosa was noted solely in infected grafts. Transmission electron microscopy showed adherence of H. pylori organisms to epithelial cell surface. In six animals, intracytoplasmic location of this bacterium was observed in the antrum or the fundus. These results allow us to propose this model as a new ex vivo model for the study of specific H. pylori-gastric cell interactions.

Animals↗
PubMed1999

Metabolism and genetics of Helicobacter pylori: the genome era.

The publication of the complete sequence of Helicobacter pylori 26695 in 1997 and more recently that of strain J99 has provided new insight into the biology of this organism. In this review, we attempt to analyze and interpret the information provided by sequence annotations and to compare these data with those provided by experimental analyses. After a brief description of the general features of the genomes of the two sequenced strains, the principal metabolic pathways are analyzed. In particular, the enzymes encoded by H. pylori involved in fermentative and oxidative metabolism, lipopolysaccharide biosynthesis, nucleotide biosynthesis, aerobic and anaerobic respiration, and iron and nitrogen assimilation are described, and the areas of controversy between the experimental data and those provided by the sequence annotation are discussed. The role of urease, particularly in pH homeostasis, and other specialized mechanisms developed by the bacterium to maintain its internal pH are also considered. The replicational, transcriptional, and translational apparatuses are reviewed, as is the regulatory network. The numerous findings on the metabolism of the bacteria and the paucity of gene expression regulation systems are indicative of the high level of adaptation to the human gastric environment. Arguments in favor of the diversity of H. pylori and molecular data reflecting possible mechanisms involved in this diversity are presented. Finally, we compare the numerous experimental data on the colonization factors and those provided from the genome sequence annotation, in particular for genes involved in motility and adherence of the bacterium to the gastric tissue.

Gene Expression Regulation, Bacterial↗
PubMed1999

Direct detection of Helicobacter pylori resistance to macrolides by a polymerase chain reaction/DNA enzyme immunoassay in gastric biopsy specimens.

BACKGROUND: The increasing use of macrolides especially in the treatment of Helicobacter pylori infection has led to an increase in resistant strains. The resistance of H pylori to macrolides, especially clarithromycin, is one of the major causes of eradication failure. In H pylori, clarithromycin resistance is due to point mutations localised in domain V of 23S rRNA. AIM: To develop a molecular technique based on amplification of a relevant fragment of the 23S rRNA and colorimetric hybridisation in liquid phase to detect directly in biopsy specimens the type of mutation associated with resistance of H pylori to clarithromycin. METHODS: Gastric biopsy samples from 61 patients were submitted to this test. The results were compared with standard methods (determination of minimal inhibition concentration, polymerase chain reaction/restriction fragment length polymorphism, and/or DNA sequencing) in order to evaluate the test and to define the cut off values, specificity, and sensitivity. RESULTS: The 14 biopsy samples in which H pylori was not detected did not give a positive result in any assay, and the 14 samples harbouring strains susceptible to clarithromycin gave a positive result with the wild type probe as expected. The 33 biopsy specimens containing resistant strains always gave a positive signal with one of the probes detecting resistant organisms, but in eight cases they also reacted with the wild type probe, indicating that a mixture of resistant and susceptible organisms was present. CONCLUSION: The importance of this new assay is that it allows the detection of multiple genotypes corresponding to either heterogeneous genotypes or mixed infections. Moreover, it allows in a single step not only the detection of H pylori but also the determination of its susceptibility to clarithromycin directly in biopsy specimens without the need for culture.

Anti-Bacterial Agents↗
PubMed1999

Domestic violence in patients visiting general practitioners--prevalence, phenomenology, and association with psychopathology.

BACKGROUND: It has been suggested that domestic violence is not only highly prevalent and associated with significant morbidity, but that it is also overlooked by medical practitioners. Despite this, few studies have focused on domestic violence in the South African setting, so that there is a paucity of data here on its prevalence, phenomenology, and associated psychopathology. METHODS: Sixteen general practitioners from the South African Sentinel Practitioner Research Network (SASPREN) screened all their female patients aged 18 years or older for a 3-month period (N = 1,050). A sociodemographic questionnaire was completed, and symptoms of post-traumatic stress disorder (PTSD) and major depression were assessed, both in subjects with a history of domestic violence and in a control group without such a history. RESULTS: 21.5% of patients reported a history of domestic violence at screening. Patients and controls did not differ significantly in terms of age or race. However, patients with a history of domestic violence were significantly more likely to be married, not to have begun a high-school education, and to be working outside the home. Both PTSD and major depression were significantly more common in patients with a history of domestic violence (35.3% and 48.2%, respectively) than in controls (2.6% and 11.4%, respectively). Compared with other patients reporting domestic violence, those with either PTSD or major depression were subjected to more violence and were more likely to report a suicide attempt. CONCLUSION: In a large, diverse population of adult female patients presenting to a range of general practitioners in South Africa, there was a high prevalence of reported domestic violence. A significant association was found between domestic violence and both PTSD and major depression, with these diagnoses indicative of increased severity of abuse and increased morbidity. Routine screening by medical practitioners of all female patients for a history of domestic violence seems warranted, and patients with a history of domestic violence should be assessed for PTSD and depression.

Adolescent↗
PubMed1998

Plasma volume expansion with Haemaccel does not impair haemostasis during reduction mammaplasty.

OBJECTIVES: An in vivo study under well-controlled conditions was undertaken to determine the effect of Haemaccel, a colloidal plasma volume expander, on normal haemostasis. METHODOLOGY: Twenty patients, who were admitted for reduction mammaplasty, were included in this study. A standardised anaesthesia protocol was followed with all patients. Ten patients received 500 ml Haemaccel and 10 controls received 1,500 ml Ringer's lactate, a crystalloid solution. The solutions were administered intravenously during surgery over a period of 30-40 minutes. Standardised clinical observations and haematological tests were done at the following time intervals: after anaesthesia but before infusion of the plasma substitute, immediately after infusion was completed, and 20, 40 and 60 minutes after infusion. RESULTS: The blood pressure, pulse rate and O2 saturation levels were not influenced by the treatment given. Haemodilution was similar for the two patient groups. The platelet count and plasma levels of fibrinogen decreased in parallel with haemodilution. Thereafter the platelet count gradually increased to pre-infusion counts at 60 minutes. The prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT) and platelet aggregation in response to adenosine diphosphate (ADP) and collagen were not affected by the plasma volume expander given. Arachidonic acid-induced aggregation decreased significantly after Ringer's lactate was given but did not change when Haemaccel was given. The bleeding time was prolonged slightly, but not significantly, from 7.4 +/- 1.6 minutes to 8.8 +/- 1.6 minutes with Ringer's lactate and from 6.9 +/- 2.0 to 9.7 +/- 3.7 minutes with Haemaccel. CONCLUSIONS: We could not find any scientific evidence that Haemaccel affects haemostasis; neither does it increase bleeding relative to Ringer's lactate.

Adult↗