Search PubMed⌕ Search

Biomedical subjects

C Denis

Publications and source records attributed to C Denis.

At least 91 records · Page 5Linked to original sources
PubMed1993

Levels of salivary IgA antibodies reactive with bacteria from dental plaque are associated with susceptibility to experimental gingivitis.

Serum IgG, IgA and IgM and salivary IgA antibody levels reactive with extracts from Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Eubacterium saburreum and Streptococcus mutans, were measured by enzyme-linked immunosorbent assay in samples from 12 persons before, during and after experimental gingivitis. The participants refrained from cleaning their teeth until 50% of their gingival units showed bleeding after gentle probing, but not longer than 15 days. Samples were taken from serum and saliva, before and during the period of experimental gingivitis, and up to 8 weeks after the start of the experiment. A pattern with minor fluctuations in specific serum and salivary antibody activities was consistently found in all patients. This indicates that immunoregulatory mechanisms succeed in maintaining unchanged antibody levels when plaque load increases. A subgroup of participants with low mean numbers of bleeding gingival units after plaque accumulation, showed significantly higher salivary IgA antibody levels reactive with S. mutans, A. actinomycetemcomitans and E. saburreum, as compared with the subgroup reaching high bleeding after probing scores (p < 0.05). When 1 person with outlying values (p < 0.05) for P. gingivalis was excluded from the tests, the former group also showed statistically significant higher salivary antibody levels to this bacterial species. High levels of salivary IgA directed against bacteria in dental plaque might thus protect against the development of gingivitis.

Adult↗
PubMed1993

Localization of von Willebrand factor binding domains to endothelial extracellular matrix and to type VI collagen.

We have recently shown that von Willebrand factor (vWF) binds to endothelial and fibroblastic extracellular matrixes (ECM) in a dose-dependent, specific, and saturable way. To localize the domain on the vWF subunit responsible for this interaction, purified proteolytic fragments of vWF were compared for their ability to inhibit 125I-vWF binding to ECM. A tryptic dimeric fragment of 116 kD (T116), extending from amino acid (aa) residues 449 to 728, produced a significant inhibition of 125I-vWF binding to the ECM. In contrast, P34 (aa 1-272), SpI (aa 911-1,365), and SpII (aa 1,366-2,050) had no significant effect on 125I-vWF binding to the ECM. Using an immunofluorescence technique, we identified type VI collagen and heparan sulfate in the endothelial ECM. 125I-vWF was found to bind specifically to purified type VI collagen. Unlabeled vWF and SpIII were able to completely inhibit 125I-vWF binding to type VI collagen. T116 and SpI appeared as competitors of this interaction, whereas P34 and SpII were not. Our data suggest that vWF binds to the endothelial ECM through the T116 fragment and that T116 and SpI each contain a binding site for type VI collagen. Heparin is known to be a vWF ligand, but did not appear as a competitor of vWF binding to the ECM, nor did heparan sulfate.

Collagen↗
PubMed1993

Characterization and distribution of alpha 2-adrenergic receptors in the human intestinal mucosa.

The subtype and the expression of the alpha 2-adrenergic receptor were investigated in the normal mucosa from human intestine by means of radioligand binding, RNase mapping, and measurement of adenylate cyclase activity. The study of the binding of the alpha 2-adrenergic antagonist, [3H]RX821002, to epithelial cell membranes indicated the existence of a single class of noninteracting sites displaying a high affinity for the radioligand (Kd = 1.1 +/- 0.5 nM). The rank order of potency of antagonists to inhibit [3H]RX821002 binding (RX821002 > yohimbine = rauwolscine > phentolamine approximately idazoxan >> chlorpromazine > prazosin) suggested that the receptor is of the alpha 2A subtype. A conclusion which is confirmed by the fact that only alpha 2C10 transcripts were found in the human intestine mucosa. Competition curves with (-)-norepinephrine demonstrated that 60% of the receptor population exhibited high affinity for agonists. This high-affinity state was abolished by the addition of GTP plus Na+ or by prior treatment of the membranes with pertussis toxin indicating it corresponded to G protein-coupled receptors. [32P]ADP-ribosylation and immunoblotting experiments identified two pertussis toxin-sensitive G proteins corresponding to Gi2 and Gi3. The study of the distribution of the receptor indicated that (a) the proximal colon is the intestine segment exhibiting the highest receptor density and (b) the receptor is predominantly expressed in crypts and is preferentially located in the basolateral membrane of the polarized cell. The distribution of the receptor along the crypt-surface axis of the colon mucosa can be correlated with a higher level of alpha 2C10-specific mRNA and a higher efficiency of UK14304 to inhibit adenylate cyclase in crypt cells.

Adenosine Diphosphate Ribose↗
PubMed1993

[Estrogen-progestin contraception. Disadvantages of estrogen reduction].

Over the past few years a number of new oral contraceptives have come into the market, with the following characteristics: reduced estrogen and progestin levels in order to reduce the incidence of cardiovascular disease, triphasic pills with maximum steroid concentrations coinciding with L.H. surge. These pills enable not only a reduction in progestin levels, but also in intercurrent bleeding. However, low steroid levels could lead to insufficient antigonadotropic effect with endogenous estrogenic secretion in some women. In fact, receptivity of targeted organs to sex steroids varies enormously between individuals. This partial inhibition of ovaries in some women poses problems of short and long term consequences: functional ovarian cysts; less protection than with traditional pills (50 micrograms ethinylestradiol) in terms of ovarian or endometrium cancer, benign breast disease... Only long term comparative and prospective studies, taking into account hormonal status and the degree of fertility and parity would enable the risks associated with these new contraceptives to be established. Consequently, in the light of our present knowledge, we recommend that low-dose oral contraception be avoided: when complete blockage of ovarian activity is required, in women with a history of ovarian cysts.

Cardiovascular Diseases↗
PubMed1992

Double-blind trial of promegestone (R 5020) and lynestrenol in the treatment of benign breast disease.

One hundred thirty-two women between the ages of 19 and 50, with various forms of benign breast diseases received 1 mg promegestone, or 0.5 mg promegestone, or 10 mg lynestrenol daily (double-blind), for 15 days per cycle, during three cycles. The groups were identical before treatment, with the exception of a longer history of mastodynia and mastopathies in the 1 mg promegestone group than in the lynestrenol group (P = 0.04) and a greater proportion of mastosis zones in the lynestrenol group as compared to the 0.500 mg promegestone group (P = 0.05). The effectiveness of lynestrenol both in terms of symptomatology (evaluated as good or excellent in 66.6% of the cases) and of clinical observations (evaluated as good or excellent in 59% of the cases) is not significantly different statistically from that of promegestone at 1 mg, whose effectiveness on symptomatology was good or excellent in 65.9% and 57.1% of the cases, respectively, or from that of promegestone at 0.5 mg/day (with 65% and 51.3% effectiveness, respectively). Clinical tolerance was rated good or excellent for 73.9% of the women on 1 mg promegestone and for 59.5% of the women on 0.500 mg promegestone, compared to 66.7% of the women on lynestrenol. No statistically significant difference was observed, neither between lynestrenol and promegestone 1 mg nor between lynestrenol and promegestone 0.5 mg. This study shows a clear improvement in functional and physical signs in patients treated with promegestone. Promegestone's efficacy is close to that of lynestrenol, a nonsteroidal progestin.2+ off

Adult↗
PubMed1992

Pre-acclimatization to high altitude using exercise with normobaric hypoxic gas mixtures.

Pre-acclimatization was conducted using a new method elaborated in our laboratory, combining high intensity exercise while breathing hypoxia normobaric gas mixtures. The training consisted in a daily training during three weeks, 6 days a week, two hours a day, on bicycle ergometer. Eighteen subjects aging 22.2 +/- 1.4 years (11 males, 7 females) were matched in two similar groups: one group trained in normoxic conditions (NG) while the other group (HG) trained with a progressive decrease of the fraction of inspired oxygen (from 12.2% to 10.0%). Maximal oxygen uptake (VO2max) were measured before and after the protocol period in both hypoxic (VO2max H, FIO2 = 10.4%) and normoxic (VO2max N) conditions, for the 2 groups. Training induced a similar O2max N increase in the two groups. The ratio VO2max H/VO2max N was calculated. As expected, in NG group, this ratio decreased significantly (from 63.9 +/- 4.3 to 57.5 +/- 3.1%, p < 0.01) after the training period compared to the initial value, diminution associated with an elevation of VO2max N (from 48.4 +/- 9.0 to 52.9 +/- 9.0 ml.min-1 x kg-1, p < 0.01). Conversely, in HG group, this ratio was not significantly diminished (from 61.7 +/- 3.8 to 60.5 +/- 5.2%, NS) in spite of a similar increase of VO2max N (from 47.5 +/- 5.5 to 50.7 +/- 4.9 ml.min-1 x kg-1, p < 0.01). This does not follow the diminution of the ratio usually described when VO2max N reach higher values.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1991

Molecular cloning and chromosomal localization of a novel human tracheo-bronchial mucin cDNA containing tandemly repeated sequences of 48 base pairs.

A lambda gt11 cDNA library constructed from human tracheo-bronchial mucosa was screened with a polyclonal antiserum raised to chemically deglycosylated pronase glycopeptides from human bronchial mucins. Out of 20 positives clones, one partial cDNA clone was isolated and allowed to map a novel human tracheo-bronchial mucin gene. It contains 48 nucleotide tandem repeats quite perfectly identical which encodes a protein containing about 50% of hydroxy amino-acids. This clone hybridized to polydisperse messages produced by human tracheo-bronchial and human colonic mucosae. The gene (proposed name MUC 4) from which cDNA is derived maps to chromosome 3.

Amino Acid Sequence↗
PubMed1991

Role of von Willebrand factor associated to extracellular matrices in platelet adhesion.

The respective role of plasmatic and endothelial extracellular matrix (ECM)-associated von Willebrand factor (vWF) in platelet adhesion was investigated at a high shear rate using a parallel-plate perfusion chamber. Incubation of the endothelial ECM with a monoclonal antibody (MoAb) to vWF, which specifically blocks vWF binding to platelet GP Ib (MoAb 322), inhibited 45% of platelet adhesion. Complete inhibition was achieved by incubating both plasma and endothelial ECM with MoAb 322 at concentrations that blocked only about 50% of adhesion when added separately. The effect of ECM-associated vWF was further demonstrated when a fibroblastic ECM, normally devoid of vWF, was coated with purified plasmatic vWF. Matrix associated-vWF was able to significantly enhance platelet adhesion in both the presence and the absence of plasmatic vWF. In contrast, this effect was not seen on endothelial ECM. Binding of exogenous vWF to the ECM was specific and dose dependent, reached the same value (500 ng/cm2) on both fibroblastic ECM and endothelial ECM, but exhibited a threefold-lower apparent dissociation constant (KD) on fibroblastic than on endothelial ECM. Our studies suggest that vWF deposited by endothelial cells in the ECM may be the most active form in platelet adhesion, whereas plasmatic vWF may only play a secondary role.

Cells, Cultured↗
PubMed1991

Effect of arginine aspartate on the exercise-induced hyperammoniemia in humans: a two periods cross-over trial.

To investigate the effect of the ingestion of arginine aspartate (AA) in the decrease of the exercise-induced accumulation of ammonia in plasma, 11 voluntary subjects took part in a cross-over study where AA effect was tested against placebo. Both treatments were randomly administered in a double-blind procedure. To ensure the subjects would be able to present reproducible exercise-testing results during repetitive sessions, they were involved before the experiment in a cycle ergometer training program during 8 weeks. This training determined a significant 14% increase (P less than 0.001) in maximal oxygen uptake (VO2 max). The treatments were administered during 10 days and the two treatments were separated by a 10 day-wash-out period. A 45 min-cycle ergometer test was performed at 80% VO2 max during the 10th day of each treatment to measure plasma ammonia (p[NH4+]) and total blood lactate (b[lact]) concentrations at rest and at the 15th, 30th and 45th min of exercise (determinations of changes from rest; delta p[NH4+] and delta b[lact]). Both concentrations were unchanged between AA and placebo at rest but a significant lesser delta p[NH4+] was found under AA at the 15th min of exercise only (P less than 0.05). On the other hand, an order effect was found for delta p[NH4+] between the two periods of randomized treatment that was interpreted as a remaining training effect. This effect was highly significant at the 30th and 45th min of exercise (P less than 0.001). It was concluded that AA effect was minor with regard to the training effect. As it was not located at the same time of exercise, AA effect would not consequently have the same functional origin (postulated increase in the peripheral clearance of ammonia) than those of training (decrease in muscle production of ammonia).

Adult↗
PubMed1990

In vitro activities of new antimicrobial agents against multiresistant Staphylococcus aureus isolated from septicemic patients during a Belgian national survey from 1983 to 1985.

The antimicrobial agents most active against bacteremic isolates of oxacillin-resistant Staphylococcus aureus isolated from 1983 to 1985 were new fluoroquinolones, including PD 117,596 and PD 127,391 (MIC for 90% of isolates [MIC90] in agar, in micrograms per milliliter, 0.1) and temafloxacin, pefloxacin, and ofloxacin (MIC90, 0.4). Other active antimicrobial agents included fusidic acid (MIC90, 0.2) and fosfomycin (MIC90, 12.5). Vancomycin was active against all isolates. Mupirocin was very active (MIC90, 0.4).

Anti-Bacterial Agents↗
PubMed1989

Effects of endurance training on hyperammonaemia during a 45-min constant exercise intensity.

Eleven laboratory-pretrained subjects (initial VO2max = 54 ml.kg-1.min-1) took part in a study to evaluate the effect of a short endurance training programme [8-12 sessions, 1 h per session, with an intensity varying from 60% to 90% maximal oxygen consumption (VO2max)] on the responses of blood ammonia (b[NH+4]) and lactate (b[la]) concentrations during progressive and constant exercise intensities. After training, during which VO2max did not increase, significant decreases in b[NH+4], b[la] and muscle proton concentration were observed at the end of the 80% VO2max constant exercise intensity, although b[NH+4] and b[la] during progressive exercise were unchanged. On the other hand, no correlations were found between muscle fibre composition and b[NH+4] in any of the exercise procedures. This study demonstrated that a constant exercise intensity was necessary to reveal the effect of training on muscle metabolic changes inducing the decrease in b[NH+4] and b[la]. At a relative power of exercise of 80% VO2max, there was no effect of muscle fibre composition on b[NH+4] accumulation.

Adult↗
PubMed1989

[The dilemma of the 2d primary molar].

Extensive carious lesions in primary molars often confront the dentist with a dilemma: extraction or restoration. The primary molar constitutes an important element in the development of the dentition. If extraction is considered, the dentist should be aware of the possible risks towards malocclusion or malposition. In order to understand these consequences a brief summary of normal dentition development is given, followed by a description of factors influencing development of dentition after premature extraction of a second primary molar. Premature extraction causes a disturbance in the eruption of the successor and migration of the neighbouring teeth. The eruption of the bicuspid can be delayed or accelerated according to the stage of root formation. The rate, amount and direction of migration depends on the extracted element, time of loss, spacing or crowding, eruption sequence, dental relationship, intercuspation, interaction of soft tissues and dental arch, supra-occlusion and the leeway space. To conclude the treatment modalities of pulp pathologies in primary molars are outlined. In children with deep carious lesions a treatment plan involves the child's medical history and social development as well as orthodontic, preventive and restorative aspects.

Child↗
PubMed1988

[Pharmacokinetics of netilmicin in cirrhotic patients with or without ascites].

The pharmacokinetics of netilmicin after intramuscular injection (2 mg/kg) was investigated comparatively in cirrhotic patients with or without ascites, and in healthy subjects. In patients with ascites, the same pharmacokinetic parameters were measured after the ascites had been cured. Twenty-four hours after intramuscular injection, the residual levels in cirrhotic patients were moderately higher than in controls, showing that liver failure or ascites did not significantly modify the pharmacokinetics of netilmicin. Serum concentrations were bactericidal. The ascitic fluid level was lower than the therapeutic range, but it was sustained for nearly 24 hours after intraperitoneal injection (2 mg/kg). These results indicate that netilmicin may be administered to cirrhotic patients without peritoneal infection using the same regimen as in healthy subjects. The peritoneal route may be preferable in case of peritoneal infection.

Adult↗
PubMed1988

Comparison of incremental and steady state tests of endurance training.

To compare the results obtained by incremental or constant work load exercises in the evaluation of endurance conditioning, a 20-week training programme was performed by 9 healthy human subjects on the bicycle ergometer for 1 h a day, 4 days a week, at 70-80% VO2max. Before and at the end of the training programme, (1) the blood lactate response to a progressive incremental exercise (18 W increments every 2nd min until exhaustion) was used to determine the aerobic and anaerobic thresholds (AeT and AnT respectively). On a different day, (2) blood lactate concentrations were measured during two sessions of constant work load exercises of 20 min duration corresponding to the relative intensities of AeT (1st session) and AnT (2nd session) levels obtained before training. A muscle biopsy was obtained from vastus lateralis at the end of these sessions to determine muscle lactate. AeT and AnT, when expressed as % VO2max, increased with training by 17% (p less than 0.01) and 9% (p less than 0.05) respectively. Constant workload exercise performed at AeT intensity was linked before training (60% VO2max) to a blood lactate steady state (4.8 +/- 1.4 mmol.l-1) whereas, after training, AeT intensity (73% VO2max) led to a blood lactate accumulation of up to 6.6 +/- 1.7 mmol.l-1 without significant modification of muscle lactate (7.6 +/- 3.1 and 8.2 +/- 2.8 mmol.kg-1 wet weight respectively). It is concluded that increase in AeT with training may reflect transient changes linked to lower early blood lactate accumulation during incremental exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Multicenter study of the sensitivity to beta-lactam antibiotics of 1,707 strains of Pseudomonas aeruginosa isolated at a general hospital].

1,707 non replicate clinical strains of Pseudomonas aeruginosa from non teaching hospitals were investigated. Beta-lactam antibiotics were tested by agar disk diffusion method. Variance analysis revealed a significant interaction between strains and experimental laboratories. The bacterial population was grouped according to the diameters of inhibition zones of antibiogram, into five phenotypes. Pseudomonas aeruginosa is frequently isolated from urines and pulmonary sampling, rarely from blood cultures. Resistance to beta-lactams increased significantly with the duration of hospitalisation, and age of patients. Clinical strains are significantly more resistant in blood cultures, and for strains isolated from reanimation. 84% of strains are susceptible to ticarcillin.

Adolescent↗