PubMed Health⌕ Search

Biomedical subjects

P Bogaerts

Publications and source records attributed to P Bogaerts.

At least 19 recordsLinked to original sources
PubMed2003

Muscle force during an acute exacerbation in hospitalised patients with COPD and its relationship with CXCL8 and IGF-I.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is often associated with peripheral muscle weakness, which is caused by several factors. Acute exacerbations may contribute, but their impact on muscle force remains unclear. Correlations between peripheral muscle force and inflammatory and anabolic markers have never been studied in COPD. The effect of an acute exacerbation on quadriceps peak torque (QPT) was therefore studied in hospitalised patients, and the aforementioned correlations were examined in hospitalised and in stable patients. METHODS: Lung function, respiratory and peripheral muscle force, and inflammatory and anabolic markers were assessed in hospitalised patients on days 3 and 8 of the hospital admission and 90 days later. The results on day 3 (n=34) were compared with those in clinically stable outpatients (n=13) and sedentary healthy elderly subjects (n=10). RESULTS: Hospitalised patients had lowest mean (SD) QPT (66 (22)% predicted) and highest median (IQR) levels of systemic interleukin-8 (CXCL8, 6.1 (4.5 to 8.3) pg/ml). Insulin-like growth factor I (IGF-I) tended to be higher in healthy elderly subjects (p=0.09). QPT declined between days 3 and 8 in hospital (mean -5% predicted (95% CI -22 to 8)) and partially recovered 90 days after admission to hospital (mean 6% predicted (95% CI -1 to 23)). QPT was negatively correlated with CXCL8 and positively correlated with IGF-I and lung transfer factor in hospitalised and in stable patients. CONCLUSIONS: Peripheral muscle weakness is enhanced during an acute exacerbation of COPD. CXCL8 and IGF-I may be involved in the development of peripheral muscle weakness in hospitalised and in stable patients with COPD.

Acute Disease↗
PubMed2003

Healing of maxillary sinusitis of odontogenic origin following conservative endodontic retreatment: case reports.

Because of the anatomical proximity, infection of posterior upper teeth can spread into the maxillary sinus. When confronted with a large persistent periapical lesion on a posterior maxillary root-treated tooth, the practitioner should question the quality of the previous endodontic treatment, evaluate the impact of the potential causes of failure and consider, in the majority of cases, the conservative non-surgical retreatment instead of extraction or periapical surgery of the dental element. This paper reports two cases of healing of extensive periapical bone destruction and of the co-existing sinus pathology of odontogenic origin after non-surgical endodontic retreatment of previously root-treated upper molars. Misconceptions concerning the role of epithelium in the periapical lesion are discussed. Also, emphasis is put on the need of precise radiological diagnosis, pre-operatively as well as post-operatively to ascertain healing and to avoid unnecessary delay in the appropriate management of these patients.

Adult↗
PubMed2001

Stability parameter estimation at ambient temperature from studies at elevated temperatures.

The determination of specific kinetic constants k(i) in pH-profile studies is often undertaken at ambient temperature. However, when dealing with a drug substance that is stable at ambient temperature, the pH-profile study is conducted at a chosen elevated temperature and the kinetic parameters are given at this particular elevated temperature. But in stability studies we generally need kinetic constants at ambient or storage temperature for practical reasons (information and storage conditions of formulation). To assess this ambient kinetic information from studies at elevated temperatures, cumulative sequential steps are usually employed with very few statistical concerns on the final estimates. The statistical problems on these final estimates in cumulative procedures are highlighted in many papers. Because these stability parameters are useful for drug formulation and storage conditions, good practical decisions have to be made on the basis of statistically unbiased identified parameters. We propose in this paper a nonlinear model that allows the direct determination of specific activation energies E(ai) that are linked to the specific kinetic constants k(i). Hence, a mathematical relationship between drug concentration C, pH, temperature T, and time t is obtained. Kinetic data from acetylsalicylic acid (ASA) hydrolysis (first-order kinetics) are used to validate the model. The results show that it is possible to obtain directly, by an extrapolation procedure, the kinetic parameters (specific kinetic constants k(i), specific activation energies E(ai), and dissociation constant pK(a)) at low temperature from data gathered at elevated temperatures using more meaningful statistics.

Data Interpretation, Statistical↗
PubMed2001

Use of the ciliated protozoan Tetrahymena pyriformis for the assessment of toxicity and quantitative structure--activity relationships of xenobiotics: comparison with the Microtox test.

Cytotoxicity and quantitative structure-activity relationships of 13 inorganic and 21 organic substances were determined using three bioassays performed on the ciliated protozoan Tetrahymena pyriformis and the luminescent bacterium Vibrio fischeri. The best concordance of toxicity results was observed between the T. pyriformis FDA--esterase activity and population growth inhibition tests for the organic compounds. The sensitivity of these two assays is compared with that of the Microtox test. The T. pyriformis FDA test showed a high sensitivity is most cases. The aim of the current research was to determine whether the relative toxicity of metal ions and organic molecules, with these three bioassays, was predictable using three ion characteristics and hydrophobicity, respectively. For metal ions, the variable that best modeled the toxicity data obtained with the two T. pyriformis tests was the softness index [sigma(p), i.e., (coordinate bond energy of the metal fluoride--coordinate bond energy of the metal iodide)/(coordinate bond energy of the metal fluoride)]. No correlation was found with the Microtox test. For organic compounds, a significant correlation was observed between the hydrophobicity coefficient and the toxicity data. This correlation is closer with the two tests using Tetrahymena.

Animals↗
PubMed2000

Improved kinetic parameter estimation in pH-profile data treatment.

Statistical problems in temperature stability parameter estimation have been the subject of many papers whereas statistics in, pH-profile parameter estimation have focused little attention. However, the conventional two step method used in data treatment in both cases leads to identical statistical problems. The aim of this study is then to introduce a method that improves statistics in pH-profile parameter estimation. A one step non-linear method that takes into account the errors in drug content determination is proposed. A mathematical relationship between drug content C, pH and time t is tested. The proposed method allows the estimation of the specific kinetic constants and the dissociation constant (pK(a)) in a single run. The most likely experimental initial drug contents C(0j),. where j is the index of a given experiment, are also determined. This approach that takes into account all relevant experimental information for the estimation of kinetic parameters is more rigorous from a statistical viewpoint than the classical two step methods. Kinetic data from acetylsalicylic acid (ASA) hydrolysis was used for the tests.

Algorithms↗
PubMed2000

[Consequences of dental restorative treatment (and of the dental materials used in its execution) on pulp tissue].

Pulp tissue may suffer from carious invasion, direct or indirect trauma and last but not least from dental treatment. As the general population grows older and retains longer its dentition, teeth will inevitably experience a complex history of multiple episodes of aggressions. It is therefore not surprising that the dental practitioner is confronted more and more with teeth reacting acutely or chronically (in other words, painfully or not) after proper dental treatment. This paper describes the common pathologic and iatrogenic events that may have an effect on the pulpal health status. Preventive endodontic treatment is to be considered in cases of extensive dental treatment.

Acute Disease↗
PubMed1999

Incorporating batch effects in the estimation of drug stability parameters using an Arrhenius model.

The nonlinear estimation of drug stability parameters (energy of activation Ea and shelf-life tY) by conventional approaches employs equations relating drug content determination C at time t and temperature T. The identification procedures lead to the determination of only one initial drug content C0 for several different experiments. However, it is well known that because of experimental concentration variation or of intentional modification of the experimental schedule, there are as many initial drug contents as experiments. For these reasons, a method which takes into account batch effects is proposed to determine stability parameters and also all initial drug contents C0j where j is the index of experiment in one step. This method is more accurate from a statistical viewpoint and is suitable for data treatment in pharmaceutical industries where the initial drug content of each batch entering the stability program can be checked a posteriori. The application of this method is shown on real kinetic data from the hydrolysis of acetylsalicylic acid (ASA).

Algorithms↗
PubMed1999

Multidrug resistance modifies polyamines uptake in P388 murine lymphoma cells: experimental and modeling approach.

Polyamines (putrescine, spermidine and spermine) are ubiquitous compounds, essential for cell growth. This paper compares the polyamine transport between sensitive P388 murine lymphoma cells and two multidrug resistant P388 sublines with the assistance of an experimental model. This new model allows the characterisation of the whole polyamines uptake and efflux. Three parameters are identified by the model: two rate constants (K+ for the uptake and K- for the efflux) which are considered as physical constants specific to the transport of one polyamine in one cell type, and Ci(o) which represents the initial intracellular concentration. This model well describes our experimental results of polyamine transport across the P388 cell plasma membrane. Multidrug resistant P388 cells exhibit spermine uptake significantly higher than that of sensitive cells when on the opposite, putrescine enters more rapidly into the sensitive P388 cells. In conclusion, comparison of polyamine transport between sensitive and multidrug resistant P388 phenotypes shows large and significant differences.

Animals↗
PubMed1999

Biological treatment of whey by Tetrahymena pyriformis and impact study on laboratory-scale wastewater lagoon process.

A procedure based on a biological treatment of whey was tested as part of research on waste treatment at the scale of small cheesemaking units. We studied the potential biodegradation of whey by a protozoan ciliate, Tetrahymena pyriformis, and evaluated the functional, microbiological and physiological disturbances caused by crude whey and the biodegraded whey in laboratory-scale pilots mimicking a natural lagoon treatment. The results show that T. pyriformis can strongly reduce the pollutant load of whey. In the lagoon pilots serving as example of receptor media, crude whey gradually but completely arrested operation, whereas with the biodegraded whey adverse effects were only temporary, and normal operation versus a control was gradually recovered in a few days.

Animals↗
PubMed1999

Expression analysis of two gene subfamilies encoding the plasma membrane H+-ATPase in Nicotiana plumbaginifolia reveals the major transport functions of this enzyme.

The plasma membrane H+-ATPase couples ATP hydrolysis to proton transport, thereby establishing the driving force for solute transport across the plasma membrane. In Nicotiana plumbaginifolia, this enzyme is encoded by at least nine pma (plasma membrane H+-ATPase) genes. Four of these are classified into two gene subfamilies, pma1-2-3 and pma4, which are the most highly expressed in plant species. We have isolated genomic clones for pma2 and pma4. Mapping of their transcript 5' end revealed the presence of a long leader that contained small open reading frames, regulatory features typical of other pma genes. The gusA reporter gene was then used to determine the expression of pma2, pma3 and pma4 in N. tabacum. These data, together with those obtained previously for pma1, led to the following conclusions. (i) The four pma-gusA genes were all expressed in root, stem, leaf and flower organs, but each in a cell-type specific manner. Expression in these organs was confirmed at the protein level, using subfamily-specific antibodies. (ii) pma4-gusA was expressed in many cell types and notably in root hair and epidermis, in companion cells, and in guard cells, indicating that in N. plumbaginifolia the same H+-ATPase isoform might be involved in mineral nutrition, phloem loading and control of stomata aperture. (iii) The second gene subfamily is composed, in N. plumbaginifolia, of a single gene (pma4) with a wide expression pattern and, in Arabidopsis thaliana, of three genes (aha1, aha2, aha3), at least two of them having a more restrictive expression pattern. (iv) Some cell types expressed pma2 and pma4 at the same time, which encode H+-ATPases with different enzymatic properties.

Amino Acid Sequence↗
PubMed1997

Treatment of root perforations with calcium hydroxide and SuperEBA cement: a clinical report.

Iatrogenic root perforations sometimes occur during root canal treatment or when preparing the root canal for a post. The inflammation in the periradicular tissues caused by root perforation reduces the prognosis of the involved tooth. The situation may be further complicated if by coronal leakage, microorganisms are allowed to infect the canal and the periradicular region. This clinical report presents a nonsurgical technique, based on the internal matrix concept, using both calcium hydroxide and SuperEBA together to repair root perforations. The author has experienced good clinical results with this perforation repair technique.

Adult↗
PubMed1996

Activity of plasma membrane H+-ATPase and expression of PMA1 and PMA2 genes in Saccharomyces cerevisiae cells grown at optimal and low pH.

Cells of Saccharomyces cerevisiae grown in media with an initial pH of 2.5-6.0, acidified with a strong acid (HCl), exhibited the highest plasma membrane H+-ATPase-specific activity at an initial pH of 6.0. At a lower pH (above pH 2.5) ATPase activity (62-83% of the maximum level) still allowed optimal growth. At pH 2.5, ATPase activity was about 30% of the maximum value and growth was impaired. Quantitative immunoassays showed that the content of ATPase protein in the plasma membrane was similar across the entire pH range tested, although slightly lower at pH 2.5. The decrease of plasma membrane ATPase activity in cells grown at low pH was partially accounted for by its in vitro stability, which decreased sharply at pH below 5.5, although the reduction of activity was far below the values expected from in vitro measurements. Yeast growth under acid stress changed the pattern of gene expression observed at optimal pH. The level of mRNA from the essential plasma-membrane-ATPase-encoding gene PMA1 was reduced by 50% in cells grown at pH 2.5 as compared with cells grown at the optimal pH 5.0, although the content of ATPase in the plasma membrane was only modestly reduced. As observed in response to other kinds of stress, the PMA2 promoter at the optimal pH was up to eightfold more efficient in cells grown at pH 2.5, although it remained several hundred times less efficient than that of the PMA1 gene.

Cell Membrane↗
PubMed1995

Functional complementation of a null mutation of the yeast Saccharomyces cerevisiae plasma membrane H(+)-ATPase by a plant H(+)-ATPase gene.

In plants, the proton pump-ATPase (H(+)-ATPase) of the plasma membrane is encoded by a multigene family. The presence within an organ of several isoforms prevents a detailed enzymatic characterization of individual H(+)-ATPases. We therefore used the yeast Saccharomyces cerevisiae as a heterologous host for the expression of PMA2, an H(+)-ATPase isoform of Nicotiana plumbaginifolia. Yeast transformed by the plant pma2 was still able to grow under conditions where the yeast ATPase gene (PMA1) was either repressed or deleted. The transformed yeast strain was resistant to hygromycin, and its growth was prevented when the medium pH was lowered to 5.0. The N. plumbaginifolia PMA2 expressed in S. cerevisiae has unusual low Km for ATP (23 microM) and high pH optimum (6.8). Electron microscopic examination revealed PMA2 in internal structures of the karmellae type which proliferated when cell growth was arrested, either at a nonpermissive pH or at the stationary phase in a minimal medium. Under the latter conditions, subcellular fractionation on sucrose gradients revealed, in addition to the expected plant PMA2 peak linked to the plasma membrane fraction, low density peak containing PMA2 and KAR2, an endoplasmic reticulum marker. These observations suggest that the partial internal accumulation of PMA2 occurs in membranes derived from the endoplasmic reticulum and largely depends on growth conditions.

Amino Acid Sequence↗
PubMed1993

Identification and characterization of a second plasma membrane H(+)-ATPase gene subfamily in Nicotiana plumbaginifolia.

A cDNA clone was isolated for a fourth pma gene encoding a putative plasma membrane H(+)-ATPase of Nicotiana plumbaginifolia. The sequence of the predicted 952 residue PMA4 polypeptide was compared with those of other known plant PMAs, revealing a higher identity with the Arabidopsis thaliana proteins (86-89%) than with the other three N. plumbaginifolia PMA proteins (80-82%). This supports the view that there are two pma subfamilies which probably arose from a gene duplication predating the separation of the Dilleniidae and Asteridae plant subclasses. Measured pma4 transcript levels indicate that pma4 is similarly expressed in root, stem, leaf, and flower tissues, contrary to the pmal-3 subfamily whose members displayed differential expression according to the organ.

Amino Acid Sequence↗
PubMed1993

[Nonvital and vital bleaching: the advise of endodontists].

Bleaching vital and non-vital has now become, for most dentists, a routine treatment. However the use of caustic products is not without risks. This article is a report of several publications that appeared in the endodontic literature cautioning the practitioner. Practical hints are given to reduce the side-effects for the patient.

Dental Pulp↗
PubMed1993

[Esthetic dentistry].

Explore the source record for details and available documents.

Dental Restoration, Permanent↗
PubMed1992

Differential expression within a three-gene subfamily encoding a plasma membrane H(+)-ATPase in Nicotiana plumbaginifolia.

Genomic and cDNA clones for the three members of a gene subfamily (pma) encoding a plasma membrane H(+)-translocating ATPase in Nicotiana plumbaginifolia were isolated and sequenced. They are between 95 and 96% identical at the deduced amino acid sequence level. Sequence comparisons with the corresponding tomato genes (Ewing, N.N., Wimmers, L.E., Meyer, D.J., Chetelat, R.T., and Bennett, A.B. (1990) Plant Physiol. 94, 1874-1881) indicate that divergence among the three N. plumbaginifolia pma genes occurred before the development of the Solanaceae family. Here, determination of pma1 transcription initiation sites reveals several 5' boundaries located 266 to 120 nucleotides upstream from the plasma membrane H(+)-ATPase translation initiation codon. The 5'-untranslated region contains a small open reading frame, 9 residues long. pma3 has a single, 264-nucleotide long 5' leader containing a 5-residue open reading frame. The latter is completely conserved in a corresponding tomato gene. These features suggest the possibility of translational regulation of plant pma genes. S1 nuclease protection assays on total cellular RNA isolated from different organs reveals that all three genes are expressed in leaf, stem, flower, and root tissues, albeit at different levels according to the organ and gene. The different genes for the plant H(+)-translocating ATPase are thus subject to differential regulation of transcription, possibly related to specific aspects of enzyme function.

Amino Acid Sequence↗