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P Lejeune

Publications and source records attributed to P Lejeune.

At least 19 recordsLinked to original sources
PubMed2004

[Malignant non-Hodgkin lymphoma presenting with Garcin's syndrome].

INTRODUCTION: R Garcin described progressive unilateral cranial nerve palsy in 1926. Garcin syndrome is characterized by progressive involvement of the cranial nerves culminating in total unilateral paralysis of all cranial nerves. Carcinoma of the skull base or ENT regions is the most common etiology. CASE REPORT: A 74-year-old man developed signs involving the left Vth (V2 and V3) cranial nerve then the VIth, VIIth and VIIIth cranial nerves and finally the IXth and Xth. MRI showed involvement of these cranial nerves with gadolinium uptake and involvement of the pons at the terminal phase. Careful ENT explorations failed to reveal a cause. The lymphocyte count was elevated in the cerebrospinal fluid. The patient died one year after diagnosis and the general autopsy was normal. The neuropathological studies led to the post-mortem diagnosis of type B non-Hodgkin lymphoma. CONCLUSION: In patients with Garcin syndrome, lymphoma is a possible diagnosis when carcinoma of the ENT regions or of the skull bases are not present.

Aged↗
PubMed2001

Complex regulatory network controls initial adhesion and biofilm formation in Escherichia coli via regulation of the csgD gene.

The Escherichia coli OmpR/EnvZ two-component regulatory system, which senses environmental osmolarity, also regulates biofilm formation. Up mutations in the ompR gene, such as the ompR234 mutation, stimulate laboratory strains of E. coli to grow as a biofilm community rather than in a planktonic state. In this report, we show that the OmpR234 protein promotes biofilm formation by binding the csgD promoter region and stimulating its transcription. The csgD gene encodes the transcription regulator CsgD, which in turn activates transcription of the csgBA operon encoding curli, extracellular structures involved in bacterial adhesion. Consistent with the role of the ompR gene as part of an osmolarity-sensing regulatory system, we also show that the formation of biofilm by E. coli is inhibited by increasing osmolarity in the growth medium. The ompR234 mutation counteracts adhesion inhibition by high medium osmolarity; we provide evidence that the ompR234 mutation promotes biofilm formation by strongly increasing the initial adhesion of bacteria to an abiotic surface. This increase in initial adhesion is stationary phase dependent, but it is negatively regulated by the stationary-phase-specific sigma factor RpoS. We propose that this negative regulation takes place via rpoS-dependent transcription of the transcription regulator cpxR; cpxR-mediated repression of csgB and csgD promoters is also triggered by osmolarity and by curli overproduction, in a feedback regulation loop.

Adhesins, Bacterial↗
PubMed2000

Developmental pathway for biofilm formation in curli-producing Escherichia coli strains: role of flagella, curli and colanic acid.

This work was performed to establish a model describing bacterial surface structures involved in biofilm development, in curli-overproducing Escherichia coli K-12 strains, at 30 degrees C, and in minimal growth medium. Using a genetic approach, in association with observations of sessile communities by light and electron microscopic techniques, the role of protein surface structures, such as flagella and curli, and saccharidic surface components, such as the E. coli exopolysaccharide, colanic acid, was determined. We show that, in the context of adherent ompR234 strains, (i) flagellar motility is not required for initial adhesion and biofilm development; (ii) both primary adhesion to inert surfaces and development of multilayered cell clusters require curli synthesis; (iii) curli display direct interactions with the substratum and form interbacterial bundles, allowing a cohesive and stable association of cells; and (iv) colanic acid does not appear critical for bacterial adhesion and further biofilm development but contributes to the biofilm architecture and allows for the formation of voluminous biofilms.

Bacterial Adhesion↗
PubMed1999

Involvement of the Cpx signal transduction pathway of E. coli in biofilm formation.

In a genetic screening directed to identify genes involved in biofilm formation, mutations in the cpxA gene were found to reduce biofilm formation by affecting microbial adherence to solid surfaces. This effect was detected in Escherichia coli K12 as well as in E. coli strains isolated from patients with catheter-related bacteremia. We show that the negative effect of the cpxA mutation on biofilm formation results from a decreased transcription of the curlin encoding csgA gene. The effect of the cpxA mutation could not be observed in cpxR- mutants, suggesting that they affect the same regulatory pathway. The cpxA101 mutation abolishes cpxA phosphatase activity and results in the accumulation of phosphorylated CpxR. Features of the strain carrying the cpxA101 mutation are a reduced ability to form biofilm and low levels of csgA transcription. Our results indicate that the cpxA gene increases the levels of csgA transcription by dephosphorylation of CpxR, which acts as a negative regulator at csgA. Thus, we propose the existence of a new signal transduction pathway involved in the adherence process in addition to the EnvZ-OmpR two-component system.

Bacterial Adhesion↗
PubMed1999

Effects of low flow on pulmonary vascular flow-pressure curves and pulmonary vascular impedance.

OBJECTIVE: Flow-pressure curves and vascular impedance are commonly used to investigate pulmonary circulation, but they may be affected at low flow by reflex neurohumoral activation. We therefore investigated the mechanical effects and the reflex effects of decreased flow on pulmonary vascular resistance and impedance. METHODS: In ten anaesthetized dogs, we compared flow-pressure curves generated in less than 10 s to prevent sympathetic activation (fast curves), or generated over 20-30 min to allow neurohumoral equilibration (slow curves), in hyperoxia (inspired oxygen, 40%) and in hypoxia (inspired oxygen, 10%), before and after adrenergic blockade by phentolamine and propranolol. Resistance was assessed from the flow-pressure relationship. Impedance was computed from instantaneous flow and pressure obtained with an ultrasonic flowmeter and a micromanometer-tipped catheter. RESULTS: At baseline, fast flow-pressure curves were steeper and had a lower pressure intercept. Transient low flow did not affect heart rate or pulmonary arterial elastance. Sustained low flow increased heart rate, resistance and elastance, suggesting baroreceptor-induced sympathetic stimulation. After adrenergic blockade, no difference persisted between effects of transient and sustained low flow. In hypoxia, slow and fast flow-pressure curves were similar. Hypoxia increased heart rate and resistance but did not decrease elastance, suggesting chemoreceptor-induced sympathetic stimulation. In hypoxia, differences between transient and sustained low flow were no longer significant, and were completely suppressed by adrenergic blockade. In two additional dogs, epinephrine infusion increased pulmonary vascular resistance and elastance. CONCLUSIONS: We conclude that (1) compared to transient low flow, sustained low flow is associated with increases in distal resistance and proximal elastance due to sympathetic stimulation and (2) these differences between the effects of transient and sustained low flow do not persist in hypoxia, because of an already present chemoreceptor-induced sympathetic stimulation.

Adrenergic alpha-Antagonists↗
PubMed1999

Diagnosis and treatment of an unusual cause of metabolic acidosis: ethylene glycol poisoning.

Ethylene glycol intoxication is a rare but dangerous type of poisoning. It causes a severe acidosis with high anion and osmolal gaps. Clinical manifestations of the ethylene glycol intoxication can be divided in three phases: a neurologic stage, with hallucinations, stupor and coma; the second stage is cardiovascular with cardiac failure. Renal failure characterizes the third stage, due to acute tubular necrosis. After aggressive gastric emptying, the main treatment is ethanol or 4-methypyrazole, which can be given either orally or intravenous, with supportive measures for all symptoms or diseased organ.

Acid-Base Imbalance↗
PubMed1999

Abiotic surface sensing and biofilm-dependent regulation of gene expression in Escherichia coli.

To get further information on bacterial surface sensing and biofilm-dependent regulation of gene expression in Escherichia coli K-12, random insertion mutagenesis with Mu dX, a mini-Mu carrying the promoterless lacZ gene, was performed with an ompR234 adherent strain, and a simple screen was developed to assess changes in gene expression in biofilm cells versus planktonic cells. This screen revealed that major changes in the pattern of gene expression occur during biofilm development: the transcription of 38% of the genes was affected within biofilms. Different cell functions were more expressed in sessile bacteria: the OmpC porin, the high-affinity transport system of glycine betaine (encoded by the proU operon), the colanic acid exopolysaccharide (wca locus, formerly called cps), tripeptidase T (pepT), and the nickel high-affinity transport system (nikA). On the other hand, the syntheses of flagellin (fliC) and of a putative protein of 92 amino acids (f92) were both reduced in biofilms. Such a genetic reprogramming of gene expression in biofilms seems to result from changes in multiple environmental physicochemical conditions. In this work, we show that bacteria within biofilms encounter higher-osmolarity conditions, greater oxygen limitation, and higher cell density than in the liquid phase.

Animals↗
PubMed1999

Hydrostatic pulmonary edema: evaluation with thin-section CT in dogs.

PURPOSE: To identify the hemodynamic determinants of ground-glass opacification on thin-section computed tomographic (CT) scans of hydrostatic pulmonary edema and to compare attenuation and subjective assessments of ground-glass opacification with extravascular lung water. MATERIALS AND METHODS: Left atrial pressure, pulmonary arterial pressure, effective pulmonary capillary pressure, and extravascular lung water were measured in six dogs before and during progressive increase of effective pulmonary capillary pressure. A thin-section CT scan was obtained at each step. Lung attenuation and subjective assessments of ground-glass opacification were compared with hemodynamic variables and extravascular lung water. RESULTS: Ground-glass opacification was identified when effective pulmonary capillary pressure equaled critical pulmonary capillary pressure. Extravascular lung water increased, and the distribution curve of lung attenuation coefficients shifted to higher attenuation from the second measurement at an effective pulmonary capillary pressure greater than the critical pulmonary capillary pressure. Attenuation was highly correlated (r = 0.98, P < .001) with extravascular lung water; ground-glass opacification was detected before a significant (P = .615, analysis of variance) increase in extravascular lung water. CONCLUSION: Thin-section CT depicts ground-glass opacification when effective pulmonary capillary pressure equals critical pulmonary capillary pressure and before a detectable increase in extravascular lung water. Attenuation reflects extravascular lung water.

Animals↗
PubMed1999

Nitric oxide synthase in human breast cancer is associated with tumor grade, proliferation rate, and expression of progesterone receptors.

Nitric oxide (NO) is generated by a family of isoenzymes named nitric oxide synthases (NOS) which includes a cytokine-inducible form, NOSII. NO is a free radical known to inhibit cell proliferation, to induce apoptosis, and to be a mediator of macrophage cytostatic and cytotoxic effects. We investigated NOS in 40 human breast carcinomas and 8 benign breast lesions. NOSII was localized in tumor cells by immunohistochemistry. NOS activity, measured with the citrulline assay, was detected in 27 of 40 tumors. Neither immunohistologic labeling nor NOS activity was detected in benign samples. NOS labeling and activity were significantly related (p < 0.02). For the first time, a significant negative relationship between NOS activity and tumor cell proliferation (p < 0.002) was found. We also showed that tumors with high NOS activity expressed progesterone receptors (p < 0.04). These results are consistent with the observation of high NOS activity in tumors with low grade (p < 0.05). These in vivo observations were related to in vitro data: cytokines (IL-1beta, IFN-gamma, and TNF-alpha) induced NOSII expression in human MCF-7 breast cancer cells, and NO inhibited their proliferation. Thus, we show herein that tumors with high NOS activity have low proliferation rate and low grade, which correlates with the in vitro observation of the inhibition of proliferation of human breast cancer cells by NO. These results may have future therapeutic implications.

Breast Neoplasms↗
PubMed1998

The role of carbohydrates in the induction of flowering in Arabidopsis thaliana: comparison between the wild type and a starchless mutant.

In order to test whether an increased export of carbohydrates by leaves and starch mobilization are critical for floral transition in Arabidopsis thaliana, the Columbia ecotype as well as its starchless mutant pgm and starch-in-excess mutant sex1 were investigated. Induction of flowering was achieved by exposure of plants to either one long day (LD) or one displaced short day (DSD). The following conclusions were drawn: (i) Both the pgm and sex1 mutants have a late-flowering phenotype in days shorter than 16 h. (ii) When inductive treatments cause a large, percentage of induced plants, there is always a large, early and transient increase in carbohydrate export from leaves. By contrast, when an inductive treatment results in only a low percentage of induced plants (pgm plants exposed to one DSD), the export of carbohydrates from leaves is not increased, supporting the idea that phloem carbohydrates have a critical function in floral transition. (iii) Starch mobilization is not required to obtain an increased carbohydrate export when induction is by one LD (extended period of photosynthesis), but is absolutely essential when induction is by one DSD (period of photosynthesis unaffected). (iv) Floral induction apparently increases the capability of the leaf phloem-loading system.

Arabidopsis↗
PubMed1998

Isolation of an Escherichia coli K-12 mutant strain able to form biofilms on inert surfaces: involvement of a new ompR allele that increases curli expression.

Classical laboratory strains of Escherichia coli do not spontaneously colonize inert surfaces. However, when maintained in continuous culture for evolution studies or industrial processes, these strains usually generate adherent mutants which form a thick biofilm, visible with the naked eye, on the wall of the culture apparatus. Such a mutant was isolated to identify the genes and morphological structures involved in biofilm formation in the very well characterized E. coli K-12 context. This mutant acquired the ability to colonize hydrophilic (glass) and hydrophobic (polystyrene) surfaces and to form aggregation clumps. A single point mutation, resulting in the replacement of a leucine by an arginine residue at position 43 in the regulatory protein OmpR, was responsible for this phenotype. Observations by electron microscopy revealed the presence at the surfaces of the mutant bacteria of fibrillar structures looking like the particular fimbriae described by the Olsén group and designated curli (A. Olsén, A. Jonsson, and S. Normark, Nature 338:652-655, 1989). The production of curli (visualized by Congo red binding) and the expression of the csgA gene encoding curlin synthesis (monitored by coupling a reporter gene to its promoter) were significantly increased in the presence of the ompR allele described in this work. Transduction of knockout mutations in either csgA or ompR caused the loss of the adherence properties of several biofilm-forming E. coli strains, including all those which were isolated in this work from the wall of a continuous culture apparatus and two clinical strains isolated from patients with catheter-related infections. These results indicate that curli are morphological structures of major importance for inert surface colonization and biofilm formation and demonstrate that their synthesis is under the control of the EnvZ-OmpR two-component regulatory system.

Alleles↗
PubMed1997

Sympathetic modulation of hypoxic pulmonary vasoconstriction in intact dogs.

BACKGROUND: The effects of the sympathetic nervous system on hypoxic pulmonary vasoconstriction (HPV) have been reported variably. We studied the effects of adrenergic receptor blockade and epidural blockade on HPV in 32 pentobarbital-anaesthetised intact dogs. METHODS: Pulmonary arterial flow-pressure relationships were determined in hyperoxia and hypoxia, at baseline and after alpha-blockade (phentolamine 2 mg/kg + 50 micrograms.kg-1.-1), beta-blockade (propranolol 2 mg/kg), alpha beta-blockade, epidural blockade (lignocaine 20 mg/kg), and alpha beta-plus epidural blockade. RESULTS: At reference flow of 3.5 1.min-1.m-2, the mean hypoxic response (hypoxia-induced increase in transpulmonary pressure gradient, each n = 8) changed from 6.0 +/- 0.9 to 3.5 +/- 1.0 mmHg after alpha-blockade, from 5.8 +/- 0.9 to 0.7 mmHg after beta-blockade, from 4.1 +/- 0.8 to 0.9 +/- 1.4 mmHg after alpha beta-blockade from 3.4 +/- 1.0 to 4.3 +/- 0.9 mmHg after epidural blockade (all P < 0.05), and was not affected by epidural blockade after alpha beta-blockade. CONCLUSIONS: In pentobarbital-anaesthetised dogs, (1) HPV is attenuated by alpha- and enhanced by beta-, alpha beta- and epidural blockade, and (2) epidural blockade has no significant adrenergic-unrelated effect on the pulmonary vasculature.

Adrenergic alpha-Antagonists↗
PubMed1997

Comparison of the effects of isoflurane with those of propofol on pulmonary vascular impedance in experimental embolic pulmonary hypertension.

Inhaled but not i.v. anaesthetics are reported to decrease pulmonary vascular resistance. The aim of this study was to compare the effects of isoflurane with those of propofol on the interaction between right ventricular (RV) function and the pulmonary vascular system in embolic pulmonary hypertension. Nine dogs received in random sequence propofol 18 mg kg-1 h-1 and 1.4% end-tidal isoflurane. Pulmonary haemodynamic state was evaluated by pulmonary arterial pressure/flow (PAP/Q) plots and pulmonary vascular impedance (PVZ) spectra. Right ventricular function was assessed by total hydraulic power (Wtot), ratio of oscillatory power (Wosc) to Wtot, and dP/dtmax. Measurements were obtained, with both anaesthetics, before and after pulmonary embolic hypertension induced by autologous blood clots. Embolism increased PAP, 0 Hz and low frequency input impedance, displaced first minimum of PAP/Q moduli and zero crossing of phase to higher frequencies, decreased characteristic impedance, decreased Wosc/Wtot without affecting Wtot, and increased dP/dtmax. Compared with propofol, isoflurane at baseline did not affect PAP/Q plots, PVZ or hydraulic power data, but decreased dP/dtmax. After embolism, isoflurane shifted PAP/Q plots to lower PAP without affecting PVZ, did not affect hydraulic power data and decreased dP/dtmax. We conclude that in canine embolic pulmonary hypertension, isoflurane compared with propofol impeded RV vascular coupling caused by decreased RV contractility, while after-load remained unchanged despite some decrease in pulmonary vascular tone.

Anesthetics, Inhalation↗