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Biomedical subjects

P Bertin

Publications and source records attributed to P Bertin.

At least 19 recordsLinked to original sources
PubMed2001

Description and application of a rapid method for genomic DNA direct sequencing.

We describe a rapid method for determining nucleotide sequences directly from total genomic DNA. This technique was used to determine genomic DNA sequences in various prokaryotic and eukaryotic microorganisms with a G+C content between 40 and 50%, e.g. Escherichia coli, Vibrio cholerae, Bacillus subtilis and Saccharomyces cerevisiae. Furthermore, the method was applied to accurately sequence up to 300 DNA base pairs in Photorhabdus luminescens, whose genome sequencing is currently under way. Taken together, these results provide evidence that our technique can be widely used to easily and efficiently determine genomic DNA sequences.

DNA, Bacterial↗
PubMed2001

Aromatase in synovial cells from postmenopausal women.

Peripheral aromatization of androgens exerts estrogenic actions in many tissues. In this study, osteoarthritis synoviocytes were examined to clarify the possible action of adrenal androgen on synovial cell. Synoviocytes from postmenopausal women are able to express aromatase mRNA. By sequence analysis, the PCR fragment (485 bp) was determined to be 100% identical to that of human placental aromatase cDNA. Moreover, this study demonstrates that adrenal androgen, androstenedione, is converted to estrone (E(1)) and estradiol (E(2)) in synoviocytes by aromatase which is positively regulated by glucocorticoids such as dexamethasone. E(2) production reduced significantly IL-6 secretion. These data provide preliminary evidence that in situ estrogen production by synoviocytes may have a role in OA susceptibility. However the role of E(2) in OA is not clear and remains to be determined.

Androstenedione↗
PubMed2001

H-NS and H-NS-like proteins in Gram-negative bacteria and their multiple role in the regulation of bacterial metabolism.

In Escherichia coli, the H-NS protein plays an important role in the structure and the functioning of bacterial chromosome. A homologous protein has also been identified in several enteric bacteria and in closely related organisms such as Haemophilus influenzae. To get information on their structure and their function, we identified H-NS-like proteins in various microorganisms by different procedures. In silico analysis of their amino acid sequence and/or in vivo experiments provide evidence that more than 20 proteins belong to the same class of regulatory proteins. Moreover, large scale technologies demonstrate that, at least in E. coli, the loss of motility in hns mutants results from a lack of flagellin biosynthesis, due to the in vivo repression of flagellar gene expression. In contrast, several genes involved in adaptation to low pH are strongly induced in a H-NS deficient strain, resulting in an increased resistance to acidic stress. Finally, expression profiling and phenotypic analysis suggest that, unlike H-NS, its paralogous protein StpA does not play any role in these processes.

Amino Acid Sequence↗
PubMed2001

Large-scale monitoring of pleiotropic regulation of gene expression by the prokaryotic nucleoid-associated protein, H-NS.

Despite many years of intense work investigating the function of nucleoid-associated proteins in prokaryotes, their role in bacterial physiology remains largely unknown. The two-dimensional protein patterns were compared and expression profiling was carried out on H-NS-deficient and wild-type strains of Escherichia coli K-12. The expression of approximately 5% of the genes and/or the accumulation of their protein was directly or indirectly altered in the hns mutant strain. About one-fifth of these genes encode proteins that are involved in transcription or translation and one-third are known to or were in silico predicted to encode cell envelope components or proteins that are usually involved in bacterial adaptation to changes in environmental conditions. The increased expression of several genes in the mutant resulted in a better ability of this strain to survive at low pH and high osmolarity than the wild-type strain. In particular, the putative regulator, YhiX, plays a central role in the H-NS control of genes required in the glutamate-dependent acid stress response. These results suggest that there is a strong relationship between the H-NS regulon and the maintenance of intracellular homeostasis.

Bacterial Proteins↗
PubMed2001

Towards a better understanding of the genetic and physiological basis for nitrogen use efficiency in maize.

To enhance our understanding of the genetic basis of nitrogen use efficiency in maize (Zea mays), we have developed a quantitative genetic approach by associating metabolic functions and agronomic traits to DNA markers. In this study, leaves of vegetative recombinant inbred lines of maize, already assessed for their agronomic performance, were analyzed for physiological traits such as nitrate content, nitrate reductase (NR), and glutamine synthetase (GS) activities. A significant genotypic variation was found for these traits and a positive correlation was observed between nitrate content, GS activity and yield, and its components. NR activity, on the other hand, was negatively correlated. These results suggest that increased productivity in maize genotypes was due to their ability to accumulate nitrate in their leaves during vegetative growth and to efficiently remobilize this stored nitrogen during grain filling. Quantitative trait loci (QTL) for various agronomic and physiological traits were searched for and located on the genetic map of maize. Coincidences of QTL for yield and its components with genes encoding cytosolic GS and the corresponding enzyme activity were detected. In particular, it appears that the GS locus on chromosome 5 is a good candidate gene that can, at least partially, explain variations in yield or kernel weight. Because at this locus coincidences of QTLs for grain yield, GS, NR activity, and nitrate content were also observed, we hypothesize that leaf nitrate accumulation and the reactions catalyzed by NR and GS are coregulated and represent key elements controlling nitrogen use efficiency in maize.

Chromosome Mapping↗
PubMed2001

Control of bacterial motility by environmental factors in polarly flagellated and peritrichous bacteria isolated from Lake Baikal.

Despite numerous studies on bacterial motility, little is known about the regulation of this process by environmental factors in natural isolates. In this study we investigated the control of bacterial motility in response to environmental parameters in two strains isolated from the natural habitat of Lake Baikal. Morphological characterization, carbon source utilization, fermentation analysis, and sequence comparison of 16S rRNA genes showed that these strains belong to two distinct genera, i.e., Enterobacter and Pseudomonas; they were named strains 22 and Y1000, respectively. Both strains swarmed at 25 degrees C and remained motile at low temperatures (4 degrees C), especially the Pseudomonas strain, which further supports the psychrotrophic characteristics of this strain. In contrast, a strong inhibition of motility was observed at above 30 degrees C and with a high NaCl concentration. The existence of flagellar regulatory proteins FlhDC and FleQ was demonstrated in Enterobacter strain 22 and Pseudomonas strain Y1000, respectively, and environmental conditions reduced the expression of the structural genes potentially located at the first level in the flagellar cascade in both organisms. Finally, as in Enterobacter strain 22, a strong reduction in the transcription of the master regulatory gene fleQ was observed in Pseudomonas strain Y1000 in the presence of novobiocin, a DNA gyrase inhibitor, suggesting a link between DNA supercoiling and motility control by environmental factors. Thus, striking similarities observed in the two organisms suggest that these processes have evolved toward a similar regulatory mechanism in polarly flagellated and laterally flagellated (peritrichous) bacteria.

Amino Acid Sequence↗
PubMed2001

Efficacy of dideoxynucleosides against human foamy virus and relationship to its reverse transcriptase amino acid sequence and structure.

Human foamy virus (HFV), a retrovirus of simian origin which occasionally infects humans, is the basis of retroviral vectors in development for gene therapy. Clinical considerations of how to treat patients developing an uncontrolled infection by either HFV or HFV-based vectors need to be raised. We determined the susceptibility of the HFV to dideoxynucleosides and found that only zidovudine was equally efficient against the replication of human immunodeficiency virus type 1 (HIV-1) and HFV. By contrast, zalcitabine (ddC), lamivudine (3TC), stavudine (d4T), and didanosine (ddI) were 3-, 3-, 30-, and 46-fold less efficient against HFV than against HIV-1, respectively. Some amino acid residues known to be involved in HIV-1 resistance to ddC, 3TC, d4T, and ddI were found at homologous positions of HFV reverse transcriptase (RT). These critical amino acids are located at the same positions in the three-dimensional structure of HIV-1 and HFV RT, suggesting that both enzymes share common patterns of inhibition.

Antiviral Agents↗
PubMed2001

The pharmacological management of drug-induced rheumatic disorders.

Many drugs can induce adverse effects such as rheumatoid disorders, which we need to be aware of in order to best detect and manage them. New drugs are constantly entering the marketplace and can cause an increasing number of disorders. Through this article, we review the prevention and pharmacological management of drug-induced rheumatic disorders. These include articular and peri-articular manifestations induced by fluoroquinolones, retinoids, cyclosporin, drug-induced disorders of bone metabolism such as corticosteroid-induced osteoporosis and drug-induced osteomalacia, and multisystemic manifestations including drug-induced lupus and arthritis induced by vaccinations and cytokines.

Animals↗
PubMed2001

Piroxicam concentrations in plasma and synovial fluid after a single dose of piroxicam-beta-cyclodextrin.

AIMS: The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) in rheumatic diseases depends on their concentrations within the joint. We determined piroxicam concentrations in plasma and synovial fluid (SF) after a single oral dose of 20 mg in the form of one tablet of piroxicam-beta-cyclodextrin. METHODS: 45 patients, aged 21 to 84 years, presenting with an effusion of the knee, related to degenerative or inflammatory joint disease, were included in this study after having given their written consent. One blood and one SF sample were drawn concomitantly in each patient from 0.5 to 48 h after NSAID administration. Piroxicam assays were performed by high performance liquid chromatography. Pharmacokinetic parameters were obtained from the mean plasma and synovial concentrations measured at various sampling times. RESULTS: The peak concentration was higher in plasma (2.51+/-0.25 microg/ml) than in SF (1.31+/-0.76 microg/ml), but the elimination half-life was much longer in SF (90.7 h) than in plasma (32.5 h). The SF/plasma area under the concentration-time curve ratio (evaluating the quantity of NSAID transferred from the blood to the joint) was equal to 0.39. CONCLUSIONS: Piroxicam contained in piroxicam-beta-cyclodextrin diffused well into the SF where its pharmacokinetic profile corresponded to that of a long half-life NSAID.

Administration, Oral↗
PubMed2000

Correlation between inorganic (heavy metals) and organic (PCBs and PAHs) micropollutant concentrations during sewage sludge composting processes.

The nature and congener composition of PCBs and PAHs present in sewage sludge composting processes was investigated. These studies included analysis of the most significant process parameters (such as pH, temperature, weight percentage variation) and in addition heavy metals whose typical composting speciation and behaviour were also considered in order to better understand organic compound time profiles. The significant correlation found between Pb, Cd, Cu and PCBs and between PAHs and Hg implies that quite a strong adsorption of PCBs onto organic matter takes place and also provides evidence for the volatilisation of PAHs. Chemical characteristics of inorganic species and organic compounds are summarised to account for the observed correlation and time trend profiles. Moreover, single congener concentrations demonstrate that the number of Cl substituents for PCBs and condensed benzene rings for PAHs determine to what extent they can be broken down for biodegradation and removed through volatilisation respectively.

Agriculture↗
PubMed2000

[Aspirin, pain and inflammation].

SUBJECT: Acetylsalicylic acid (ASA) is among the most commonly analgesic, antipyretic and anti-inflammatory used drugs. The anti-inflammatory effects of ASA are mediated by the inhibition of cyclooxygenase enzymes with the subsequent decrease of prostaglandin synthesis. NEW DATA: However, since this discovery of Vane in 1971, much of other mechanisms of anti-inflammatory action, without relation with cyclooxygenases, have been proposed. ASA has peripheric analgesic properties by reducing prostaglandin biosynthesis. But there is evidence that the analgesic effects could be mediated by central mechanisms with changes in the monoaminergic and opioid systems. ASA is essentially used in moderate pains with an inflammatory component (rheumatological disorders, headaches, dental and postoperative pains). PERSPECTIVES: The clinical use of ASA at anti-inflammatory dose is less frequent because the other non steroidal anti-inflammatory drugs are as effective as ASA, but they are associated with less side effects. Nevertheless, the synergism of ASA and morphine association and the possible involvement of the central serotonergic and opiatergic systems in the antinociceptive activity of ASA could confer a greater role of ASA in pain management.

Adult↗
PubMed2000

Isolation and characterization of vicH, encoding a new pleiotropic regulator in Vibrio cholerae.

During the last decade, the hns gene and its product, the H-NS protein, have been extensively studied in Escherichia coli. H-NS-like proteins seem to be widespread in gram-negative bacteria. However, unlike in E. coli and in Salmonella enterica serovar Typhimurium, little is known about their role in the physiology of those organisms. In this report, we describe the isolation of vicH, an hns-like gene in Vibrio cholerae, the etiological agent of cholera. This gene was isolated from a V. cholerae genomic library by complementation of different phenotypes associated with an hns mutation in E. coli. It encodes a 135-amino-acid protein showing approximately 50% identity with both H-NS and StpA in E. coli. Despite a low amino acid conservation in the N-terminal part, VicH is able to cross-react with anti-H-NS antibodies and to form oligomers in vitro. The vicH gene is expressed as a single gene from two promoters in tandem and is induced by cold shock. A V. cholerae wild-type strain expressing a vicHDelta92 gene lacking its 3' end shows pleiotropic alterations with regard to mucoidy and salicin metabolism. Moreover, this strain is unable to swarm on semisolid medium. Similarly, overexpression of the vicH wild-type gene results in an alteration of swarming behavior. This suggests that VicH could be involved in the virulence process in V. cholerae, in particular by affecting flagellum biosynthesis.

Amino Acid Sequence↗
PubMed2000

Drug-induced rheumatic disorders: incidence, prevention and management.

The purpose of this article is to review the causes, the clinical manifestations and the management of the more frequent drug-induced rheumatic disorders. These include: (i) articular and periarticular manifestations induced by fluoroquinolones, nonsteroidal anti-inflammatory drugs, injections of corticosteroids, and retinoids; (ii) multisystemic manifestations such as drug-induced lupus and arthritis induced by vaccination, Bacillus Calmette-Guerin therapy and cytokines; (iii) drug-induced disorders of bone metabolism (corticosteroid-induced osteoporosis, drug-induced osteomalacia and osteonecrosis); and (iv) iatrogenic complex regional pain syndromes. Disorders caused by nonpharmacological and rarely used treatments have been deliberately excluded. Knowledge of these drug-induced clinical symptoms or syndromes allows an earlier diagnosis and treatment, and earlier drug withdrawal if necessary. With the introduction of new medications such as the recombinant cytokines and antiretroviral treatments, the number of drug-induced rheumatic disorders is likely to increase.

Animals↗
PubMed2000

Articular diffusion of meloxicam after a single oral dose: relationship to cyclo-oxygenase inhibition in synovial cells.

OBJECTIVE: To investigate the distribution of meloxicam in the human knee joint and to compare it with the inhibition of cyclo-oxygenase (COX) activity in synovial cells. DESIGN: Prospective pharmacokinetic study and in vitro laboratory investigation. PATIENTS AND PARTICIPANTS: 42 male and female patients aged 26 to 85 years hospitalised for rheumatic disease and requiring a diagnostic and/or therapeutic knee puncture. METHODS: After a single oral dose of meloxicam 15mg, synovial fluid and blood samples were collected once per patient at various intervals after administration. Meloxicam concentrations were determined by a validated high performance liquid chromatography assay, protein binding by equilibrium dialysis, and pharmacokinetic parameters were calculated by noncompartmental analysis from the mean drug concentration-time profiles. The inhibitory effect of meloxicam on COX activity was investigated separately in unstimulated or interleukin-1beta-stimulated human synovial cells from osteoarthritic patients. RESULTS: Meloxicam was found in synovial fluid at the earliest sampling time (1 hour). Peak concentrations were reached approximately 6 hours postdose in both plasma (842 microg/L) and synovial fluid (320 microg/L). A plateau was observed after the distribution phase (6 hours), corresponding to a constant ratio of drug concentration between synovial fluid and plasma of about 0.47. This ratio was higher in patients with acute inflammation (0.58) than in those with no inflammation (0.38). Meloxicam was extensively bound to protein, mainly to serum albumin. The area under the drug concentration-time curve (AUC) in plasma was more than 2.5 times that in synovial fluid. The AUC for free meloxicam was similar in plasma and synovial fluid. The 50% inhibitory concentrations (IC50) for basal and stimulated COX activity in human synovial cells were 33.7 nmol/L (11.8 microg/L) and 2.0 nmol/L (0.70 microg/L), respectively. The free concentration of meloxicam in synovial fluid was higher than the IC50 for stimulated COX activity from 6 to 36 hours postdose. CONCLUSION: On the basis of free synovial concentrations and the IC50 for stimulated COX activity, meloxicam is expected to have a long duration of action. Inhibition of COX activity is expected to be more marked in inflamed synovium compared with non-inflamed synovium.

Administration, Oral↗
PubMed2000

Current use of analgesics for rheumatological pain.

Rheumatological pain is the most frequent pain doctors have to deal with. Faced with a patient experiencing pain, the clinician must work towards global management of the patient, including the prescription of analgesics. The results of a European survey amongst 722 general practitioners, rheumatologists, orthopaedic surgeons and internal specialists showed that about half of all patients treated for moderate-to-severe pain suffered from musculoskeletal pain. Despite this high treatment frequency, the management of rheumatological pain was generally perceived as problematic by the respondents. The drugs prescribed to treat rheumatological pain differed from country to country, but NSAIDs were generally the most-prescribed substances. Important reasons given for selecting analgesics included efficacy and tolerability, but also tolerance and addiction potential. NSAIDs are common first-line drugs, but their adverse reactions and interactions have led to paracetamol being recommended more often in this role. However, it has been recently demonstrated that the efficacy of paracetamol is often inadequate. On the other hand, the reduced risk of GI toxicity of the new COX-2 selective inhibitors could assure them a major role in mild-to-moderate rheumatological pain treatment. When any of these drugs are no longer effective, or when a patient cannot tolerate their adverse reactions, weak opioids should be considered. Tramadol is one such drug, which is gaining popularity for the treatment of moderate-to-severe rheumatological pain. Finally, strong opioids should be used in selected patients when all other options have been exhausted.

Analgesics↗