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P Perrin

Publications and source records attributed to P Perrin.

At least 19 recordsLinked to original sources
PubMed2007

Light-responsive hydrophobic association of azobenzene-modified poly(acrylic acid) with neutral surfactants.

Photoresponsive association between azobenzene-modified poly(acrylic acid)s (AMPs) and the nonionic surfactants tetraethylene glycol monododecyl ether and octadecyl ether (C12E4 and C18E4) has been achieved in dilute aqueous solution. The binding was investigated by (i) spectrophotometry that probes the polarity close to the azobenzene chromophore, (ii) capillary electrophoresis to obtain the amount of C12E4 bound per polymer chain, and (iii) pressure-area curves of Langmuir films to obtain information on the adsorption of AMP at the water-C18E4 interface. Increasing hydrophobicity of AMP (with increasing degree of modification with azobenzene side-groups) tightened the association with C12E4 in the dark. Exposure to UV light rapidly converted the azobenzene to their more polar cis isomer, which in turn weakened the association with surfactant. Almost complete photorelease of bound C12E4 was obtained with the optimal structure of AMP. Adsorption on large interfaces is much less sensitive to light. The possible origin of the photoresponse is analyzed in terms of AMP affinity for surfactant assemblies and azobenzene penetration in the hydrophobic core of micelles. We propose that the photoswing of polarity is amplified by the binding to small micelles because of the small number of anchors involved. A few azobenzene anchors afford tight binding in the dark, but also detach more easily than the whole AMP chain upon photoisomerization.

Journal Article↗
PubMed2006

Adsorption of randomly annealed polyampholytes at the silica-water interface.

We have investigated the adsorption of randomly annealed polyampholytes containing [2-(dimethylamino)ethyl methacrylate)] (DMAEMA), methacrylic acid (MAA), and [3-(2-methylpropionamido)propyl] trimethylammonium chloride (MAPTAC) with various molar compositions. The adsorption was performed from dilute aqueous solutions onto silicon substrates. The adsorbed layers were characterized by reflectivity techniques such as reflectometry, ellipsometry, and neutron specular reflection. As expected for annealed polyampholytes, the adsorption was found to depend strongly on the pH, with a maximum within the isoelectric domain of the polyampholyte. The monomer volume fraction profiles of the adsorbed layers were determined from neutron specular reflection measurements. In the isoelectric domain, the polyampholyte chains adopt a compact conformation, with a layer thickness of about 60 A. The polyampholyte layer is as dense as the adsorbed layer of fully charged polyelectrolyte but much thicker. Finally, we found that changing the ratio of neutral units along the polyampholyte chain in the isoelectric domain had no significant effect on the concentration profile of the adsorbed layer.

Journal Article↗
PubMed2006

Current physical activity improves balance control during sensory conflicting conditions in older adults.

Aging process is characterized by difficulties in ensuring balance control, especially in conditions of reduced or conflicting sensory information, leading to an increased risk of falling. Conversely, the practise of physical activities (PA) has been recognized as a good approach to improve the quality of balance control. This study aimed to investigate the influence of current and/or past PA on balance-related neurosensorial organization in older adults on the maintenance of the upright stance, especially during sensory conflicting situations. Postural control was evaluated by means of the Sensory Organization Test on 130 healthy noninstitutionalized volunteers aged over 65, split into four groups according to the presence or absence of PA before or after retirement. Subjects who practised PA for a long time (Gr1) and subjects who started PA after retirement (Gr2) displayed the best postural performances and better managed sensory conflicting situations compared to subjects who had stopped PA for many years (Gr3) and subjects who had never practised PA (Gr4). Multiple regression analyses revealed that current PA was the major determinant for postural parameters during sensorial conflict compared to age, gender, body mass index and past PA. Regular PA, even when started late in life, allows appropriate reorganization of the different components of postural control during sensory conflicting situations. Indeed, active subjects were more able to compensate for suppressed or perturbed sensory information by an increased usage of another referential and so to correct their posture by adopting a more appropriate balance strategy. Thus, PA counteracts the age-related decline of postural control and could consequently reduce the risk of falling.

Adaptation, Physiological↗
PubMed2006

Determinants of accident proneness: a case-control study in railway workers.

BACKGROUND: Accident proneness or workers who have more frequent occupational injuries is common but the role of occupational and individual factors has rarely been studied. AIM: To assess the relationships of certain occupational and individual characteristics with frequency of occupational injuries. METHOD: This case-control study included 1305 male workers with occupational injuries during 1999-2000 and 1305 controls from a railway company. A standardized questionnaire was completed by the occupational physician in the presence of the subject. The data were analysed using logistic regression. RESULTS: Having more than one injury was associated with short service in the present job, younger age, sleep disorders, smoking, requesting a job change, physical disability and lack of physical activity. Safety training was negatively related to injury frequency. Short service in the present job was the only significant factor for single injuries. CONCLUSION: This study identified a number of work and individual factors that predicted occupational injury frequency and may be useful in designing preventative measures. Occupational physicians could assist workers to be more aware of the risks and to find remedial measures.

Accident Proneness↗
PubMed2006

[Screening for prostate cancer: arguments "against"].

Prostate cancer screening is controversial since PSA assay has been made available. Screening supporters consider that early diagnosis allows better and less aggressive treatment. These arguments lie on longitudinal cohort studies without controls. Randomized studies are required to assess the correlation between screening and mortality lowering. Two studies are being performed and their results will be available within three or four years. Consequently, the validity of screening is unknown. Nevertheless, the analysis of various parameters demonstrates that the reduction of cancer mortality related to screening is low. According to these data and as recommended by health institutions prostate cancer screening is not required. At the present time, detection asked by the patient himself remains the good attitude between negligence and excessive attitude.

Humans↗
PubMed2006

[Active follow-up of prostate cancers].

Today, earlier diagnosis of prostate cancer has allowed including, beside standard curative treatments, active follow-up of the disease. Such therapeutic management is based on a better knowledge of the natural history of prostate cancer and on possible detection of cases with slow progression. However, all criteria of selection of tumours that are likely to benefit from such surveillance are not always reliable and in some cases invasive treatment should replace surveillance. Analysis of active follow-up series shows that patients who benefit from such treatment have an unchanged prognosis. Active surveillance of prostate cancers may be considered a valuable option provided very strict limits are established regarding patients selection and follow-up.

Follow-Up Studies↗
PubMed2006

Rabies: epidemiological tendencies and control tools.

Rabies encephalitis still generates 50,000 human deaths/year. It is due to neuron infection by lyssaviruses. Seven genotypes (GT) are currently distinguished within the Lyssavirus genus which segregate in two phylogroups (PG). This classification is constantly evolving due to isolation of new lyssaviruses within bat populations. Functional differences exist between GTs in term of neurotropism, pathogenesis, induction of apoptosis, immunogenicity, and their molecular basis are starting to be elucidated. Lyssavirus vectors are mammals, preferentially from the Carnivora and Chiroptera orders. Phylogenetic reconstruction strongly supports that lyssaviruses evolved in chiropters long before the emergence of carnivoran rabies which very likely occurred through host-switchings from bats to carnivores. If dog rabies control is possible by vaccination and population control, if oral vaccination demonstrated its potential to eliminate rabies from a terrestrial wildlife reservoir (fox in Western Europe), it is unrealistic today to clear lyssaviruses from bats, while bat rabies is a growing concern for both public and animal health. As bat transmit divergent lyssavirus GTs which are not well prevented by available vaccine strains, there is a need to increase the protection spectrum of vaccines. DNA-based immunization with plasmids expressing chimeric G proteins (fusion of two halves from different GTs) was shown to be effective in inducing a complete immune response and to broaden the spectrum of rabies vaccines toward lyssavirus vaccines. Further, the lyssavirus G protein can carry foreign epitopes/antigens in the perspective of multivalent vaccines against various zoonoses of carnivores.

Animals↗
PubMed2005

p53 immunodetection of liquid-based processed urinary samples helps to identify bladder tumours with a higher risk of progression.

p53 could help identify bladder tumour cases with a risk of progression from superficial to invasive disease. Semiautomatic, liquid-based cytology (LBC) techniques offer an opportunity to standardise molecular techniques. The aim of our study was to investigate whether LBC could improve p53 immunolabelling, and to assess whether urinary p53 could have a prognostic value. Immunoreactivity for p53 was studied in 198 urine samples after treatment with the Cytyc Thinprep processor. After antigen retrieval, cells were labelled with a monoclonal antibody that recognises both wild-type and mutant form of the p53 protein (Clone DO-7, Dako), 1/1000. Positivity for p53 was assessed in 17.2% of the cases. High-grade (G3) tumours were positive in 74.1% of the cases. Comparatively, low-grade (G1-2) urothelial carcinomas were positive in 23.5% of the cases. During a median follow-up period of 26 months, recurrence was observed in 52.9% of the cases with p53 overexpression, and in only 10.9% of negative cases (P < 0.001). The progression rate was 35.3% of p53-positive cases vs 5.5% of p53-negative cases (P < 0.001). Progression-free survival was significantly shorter in patients with p53 accumulation (P = 0.007). In a multivariate analysis stratified on grade and stage, p53 was an independent predictor of overall survival (P = 0.042). The results show that using Thinprep LBC, p53 immunolabelling of voided urothelial cells allows most high-grade tumours to be detected and may help identify cases with a higher risk of recurrence and progression.

Adult↗
PubMed2005

Relationship between lower urinary tract symptoms frequency assessed by the IPSS and bothersomeness (SPI) among men older than 50 years old.

OBJECTIVE: The International Prostatic Symptom Score (IPSS) evaluates urinary disorder symptoms frequently associated with benign prostatic obstruction, but does not take into account the bothersomeness they induce. The Symptom Problem Index (SPI) evaluates the degree of discomfort associated with each question on the IPSS. Our objective was to explore the relationships between these two rating scales. METHODS: The IPSS and SPI self-administered scores were administrated to a cohort of 907 patients presenting with LUTS suggestive of BPO (Benign Prostatic Obstruction), for which 722 patients were evaluable. This diagnosis was made by GP (General Practitioner) in the 3-month period before their inclusion in the study. The correlation between SPI and IPSS was investigated and each symptom was classified according to its frequency and according to the bothersomeness it induced. The degree of bothersomeness associated with each IPSS symptom was evaluated and quantified based on quadratic function estimates. RESULTS: The mean IPSS score was 12.6+/-6.4, the mean SPI score was 12.2+/-6.5. The correlation coefficient between the IPSS and SPI scores was 0.70; the scores from the 2 rating scales showed a very high variability. On a 0-100% scale, where 100% represents a maximum bothersomeness, the induced bothersomeness ranged from 0 to 22.6% depending on the 7 symptoms. CONCLUSIONS: The two questionnaires do not collect the same information. The extent of variability between the two scales confirms that one scale cannot be replaced by the other. Considering the importance of bothersomeness associated with lower urinary tract symptoms for the therapy decision, the joint use of the IPSS and SPI seems appropriate.

Aged↗
PubMed2005

Preservation of prostate during radical cystectomy: evaluation of prevalence of prostate cancer associated with bladder cancer.

OBJECTIVES: To estimate the frequency and characteristics of prostatic lesions discovered incidentally in radical cystoprostatectomy specimens and to determine whether any factors would allow for the detection of prostate cancer preoperatively. METHODS: A total of 100 radical cystoprostatectomy specimens with orthotopic bladder reconstruction were performed for malignant bladder disease between 1990 and 2000. The mean patient age at surgery was 62 +/- 8 years (range 32 to 75). Digital rectal examination and prostate-specific antigen (PSA) assay were done routinely before surgery. During the 10-year study period, the same pathologist examined the prostatic tissues from radical cystoprostatectomy specimens using McNeal's technique on fine slices every 2.5 mm. RESULTS: The overall incidence of prostate cancer discovered incidentally in radical cystoprostatectomy specimens was 51%, of which 29% were microcancers (volume less than 0.5 cm3) and 22% were significantly larger (volume 0.5 cm3 or more). The mean Gleason score was 6. Of the tumors, 24% could be considered "clinically nonsignificant" (less than 0.5 cm3 and Gleason score less than 7). The mean preoperative PSA level was 4.13 +/- 1.36 ng/mL. Of 66 patients with a PSA level of less than 4 ng/mL (mean PSA 1.5 +/- 0.8) and a normal digital rectal examination before surgery, 50% had prostate cancer, of which 69% were microcancers. CONCLUSIONS: The prevalence of prostate cancer (51%) in our series is among the highest in published reports. Furthermore, our results stress that currently no factors are available to enable the detection of "clinically significant" prostate cancer preoperatively.

Adult↗
PubMed2005

[Skull vibratory test in partial vestibular lesions--influence of the stimulus frequency on the nystagmus direction].

INTRODUCTION: Results of the skull vibratory test (SVT) in partial unilateral vestibular peripheral lesions (PUVL) are different from the results in total vestibular lesions (TUVL). AIM: To reveal a correlation between the results of the analysis of the skull vibratory nystagmus (SVN) horizontal component and the side of the lesion; to correlate these results with the stimulus frequency. To find out a predictive correlation between the SVN horizontal and vertical components and the topography of a vestibular lesion. To appreciate the degree of vestibular deafferentation (extended to high frequencies) provoked by gentamicin labyrinthectomy and its efficiency in Meniere's disease. PATIENTS AND METHODS: 53 patients with a SVN and a PUVL were included and compared with 10 TUVL and 10 normal subjects. Protocol included a HST (2 Hz), a SVT at 30, 60 and 100 Hz and a caloric test. Recordings were performed with a 2D and 3D VNG device. RESULTS: In PUVL, SVN at 30, 60 and 100 Hz was obtained in 80, 90 and 90% of cases respectively. SVN is correlated with the side of the lesion at 30, 60 and 100 Hz respectively in 65%, 63%, 80% of cases. SVN is not correlated with the side of the lesion in 20% of Meniere's disease, in 8% of vestibular neuritis and in 6% of vestibular schwannoma. In PUVL HSN is correlated with the side of the lesion in 69% of cases. The direction of the HSN and of the SVN was different in 23% when the nystagmus attended at the same time for both tests. In PUVL the direction of the SVN is different at 100 Hz and 30 Hz in 16% of cases when they are concomittant on the same patient. After Gentamicine labyrinthectomy, the coherence of the results in caloric test, HSN and SVN (areflexy and lesional nystagmus beating toward the safe side) was correlated with the efficiency of the therapy. A SVN vertical component was met in 10% of PUVL (essentially in anterior canal dehiscence and few cases of partial labyrinthitis). The horizontal SVN SPV is significantly slower in PUVL than in TUVL patients (p=0.0004). CONCLUSIONS: The SVT is a vestibular global and rapid test which explores high frequencies. In PUVL the direction of SVN is not always predictive of the side of the lesion and is sometimes depending on the stimulus frequency, the state of the vestibular lesion, the vestibular structure concerned (1/2 circular canals or otolithic organs) and the kind of sensory cells implicated in the lesion. In TUVL The direction of the SVN is always coherent with the side of the lesion (this is useful to predict the efficiency of a Gentamicine Labyrinthectomy). A SVN vertical component can mean a lesion of the vertical canal in PUVL.

Adolescent↗
PubMed2004

Interface composition of multiple emulsions: rheology as a probe.

We have investigated the dynamic rheological properties of concentrated multiple emulsions to characterize their amphiphile composition at interfaces. Multiple emulsions (W1/O/W2) consist of water droplets (W1) dispersed into oil globules (O), which are redispersed in an external aqueous phase (W2). A small-molecule surfactant and an amphiphilic polymer were used to stabilize the inverse emulsion (W1 in oil globules) and the inverse emulsion (oil globules in W2), respectively. Rheological and interfacial tension measurements show that the polymeric surfactant adsorbed at the globule interface does not migrate to the droplet interfaces through the oil phase. This explains, at least partly, the stability improvement of multiple emulsions as polymeric surfactants are used instead of small-molecule surfactants.

Acrylates↗
PubMed2003

[Nystagmus and vibration test research of mechanisms, theoretical methods: on 52 cases of unilateral vestibular lesions].

OBJECTIVE: The aim of the present study was to examine the characteristics of the Vibratory Nystagmus (VN) optimise the topography and the frequency of the stimulus, determine the origin of the VN and analyse its clinical implications. MATERIAL AND METHOD: 52 severe unilateral vestibular lesions (SUVL) (post-surgical vestibular areflexy) were studied. The vibratory nystagmus was measured by 2D and 3D videonystagmography (Synapsis, France). The stimulus was applied with a 3S vibrator at the vertex, both mastoïds, and posterior cervical muscles at frequencies ranging from 20 to 150 Hz. For topographic optimisation, stimulation was given with S vibrator (Synapsis, France) at 100 Hz. The interferences between the vibratory test (VT) and the caloric test (CT) were studied on the normal ear (in 11 subjects). The same study was carried with the optokinetic test. RESULTS: The VT revealed a defective nystagmus at all frequencies of stimulation. Optimal response was obtained in a band frequency of 80-120 Hz. Stimulations at 100 Hz showed optimal responses for mastoïd topography (responses in 96% of the cases). Stimulation at the posterior cervical muscles and at the vertex indicated respectively a response in 90% and 60% of the cases. The efficiency of the mastoïd stimulation is not correlated with the side of stimulation (p = 0.9). The interference between the VT and caloric test (CT) at cold water (30 degrees et 20 degrees C) exhibited the inversion of the caloric nystagmus during the vibrator stimulation. The resulting nystagmus is respectively an algebric subtraction or addition between the pre-existing caloric nystagmus and the value of the vibratory nystagmus obtained before caloric test. Adaptation of the VN is moderate. The interference between the VT and the optokinetic test resulted in a subtraction or addition effect, according to the side of the lesion and the direction of the optokinetic stimulus. CONCLUSION: The VT is an efficient stimulation in mastoïd topography. The vestibular contribution is bilateral by bony conduction of the vibration, it explores frequencies ranging from 30 to 120 Hz, with a maximum of response at 100 Hz. The VT interacts with the caloric test and the optokinetic test. The stimulation is very strong, and is able to inverse the caloric nystagmus at cold water stimulation (20 degrees C). In labyrinthine-defective subjects, the VN is always defective at all frequencies, whatever is the topographic location of the stimulus, and the position of the head.

Caloric Tests↗
PubMed2002

Renal handling of salt and water in humans during exercise with or without hydration.

Plasma sodium (Na+) concentration, i.e. natraemia, results from body tonicity equilibrium. During exercise, a change in body tonicity can result from an imbalance between intake and loss of Na+, potassium (K+) and water (H2O) due to renal and/or extra-renal mechanisms. Whether exercise-induced changes in kidney function could be responsible for such an imbalance was studied by measuring glomerular filtration rate (creatinine clearance), proximal tubule activity (lithium clearance) and renal handling of Na+ and K+ at rest and during exercise. Since hyponatraemia during or after exercise has been reported, we also investigated whether a water load could be appropriately excreted during exercise. Ten young men pedalled on a cycle ergometer at 60% of maximal oxygen uptake for 45 min with (HE, hydrated exercise) or without (DHE, dehydrated exercise) a supply of water. In both conditions, creatinine, lithium, and electrolyte (Na+ + K+) clearances decreased and natraemia did not change. The DHE induced a loss of body mass (-1.29%), decreased diuresis and large extra-renal water loss [mean (SEM)] [880 (73) ml]. The HE led to no loss in body mass, increased diuresis and lower extrarenal water loss [680 (48) ml]. Electrolyte-free water excretion, negative for DHE, represented 60% of diuresis during HE. Thus the kidney, by increasing electrolyte reabsorption mainly in the proximal tubule, and appropriately excreting a water load, seems efficacious in regulating extracellular fluid volume and body tonicity and so not responsible for the imbalance between (Na+ + K+)/H2O intake and loss. Therefore, extra-renal changes could be the main causes of exercise-induced tonicity imbalances which could ultimately lead to dysnatraemia.

Adaptation, Physiological↗
PubMed2002

Long-term recurrence of primary amyloidosis of the bladder.

An 84-year-old man presented to our department with a recurrence of a primary amyloidosis of the bladder 14 years after the first diagnosis. Follow-up had been stopped 5 years after the first procedure because no cystoscopic anomalies were noted. General evaluation confirmed the diagnosis of primary amyloidosis. The lesions were endoscopically resected. At the 3-year follow-up, the patient was free of symptoms and had remained cystoscopically free of disease. However, stable amyloidosis deposits have always been noted on the computed tomography scans. This case emphasizes the necessity of a longer follow-up, including computed tomography of the pelvis, during the 10 to 15 years after the first occurrence of the disease.

Aged↗