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F Portet

Publications and source records attributed to F Portet.

14 recordsLinked to original sources
PubMed2006

Prevention trials in Alzheimer disease: one step forward?

Finding strategies that prevent or delay the onset of dementia in Alzheimer disease (AD) will be a challenge for the years to come. Prevention trials in AD pose several unresolved questions, including methodologic, scientific, medical, regulatory, and ethical issues. A critical concern is the benefit and relative risk of giving a treatment to non-demented patients or to asymptomatic subjects. Some trials are under way and will perhaps move the field of prevention of dementia one big step forward.

Alzheimer Disease↗
PubMed2006

Mild cognitive impairment (MCI) in medical practice: a critical review of the concept and new diagnostic procedure. Report of the MCI Working Group of the European Consortium on Alzheimer's Disease.

Mild cognitive impairment (MCI) was proposed as a nosological entity referring to elderly people with mild cognitive deficit but no dementia. MCI is a heterogeneous clinical entity with multiple sources of heterogeneity. The concept of MCI was reviewed and a diagnostic procedure with three different stages was proposed by the European Consortium on Alzheimer's Disease Working Group on MCI. Firstly, MCI should correspond to cognitive complaints coming from the patients or their families; the reporting of a relative decline in cognitive functioning during the past year by a patient or informant; cognitive disorders as evidenced by clinical evaluation; absence of major repercussions on daily life; and absence of dementia. These criteria, similar to those defined during an international workshop in Stockholm, make it possible to identify an MCI syndrome, which is the first stage of the diagnostic procedure. Secondly, subtypes of MCI had to be recognised. Finally, the aetiopathogenic subtype could be identified. Identifying patients at a high risk for progression to dementia and establishing more specific and adapted therapeutic strategies at an early stage, together with more structured overall management, is made possible by the diagnostic procedure proposed.

Activities of Daily Living↗
PubMed2005

Evaluation of real-time QRS detection algorithms in variable contexts.

A method is presented to evaluate the detection performance of real-time QRS detection algorithms to propose a strategy for the adaptive selection of ORS detectors, in variable signal contexts. Signal contexts are defined as different combinations of QRS morphologies and clinical noise. Four QRS detectors are compared in these contexts by means of a multivariate analysis. This evaluation strategy is general and can be easily extended to a larger number of detectors. A set of morphology contexts, corresponding to eight QRS morphologies (normal, PVC, premature atrial beat, paced beat, LBBB, fusion, RBBB, junctional premature beat), was extracted from 17 standard ECG records. For each morphology context, the set of extracted beats, ranging from 30 to 23000, was resampled to generate 50 realisations of 20 concatenated beats. These realisations were then used as input to the QRS detectors, without noise, and with three different types of additive clinical noise (electrode motion artifact, muscle artifact, baseline wander) at three signal-to-noise ratios (5 dB, -5 dB, -15 dB). Performance was assessed by the number of errors, which reflected both false alarms and missed beats. The results show that the evaluated detectors are indeed complementary. For example, the Pan-Tompkins detector is the best in most contexts but the Okada detector generates fewer errors in the presence of electrode motion artifact. These results will be particularly useful to the development of a real-time system that will be able to choose the best ORS detector according to the current context.

Algorithms↗
PubMed2005

[Behavioral and psychological symptoms in dementia: description and management].

Behavioral and Psychological Symptoms in Dementia (BPSD) are, beside cognitive disorders, major features of Alzheimer's disease and related disorders. Diagnosis is important to enhance our knowledge of the pathophysiology of dementia and of their functional consequences for patients and caregivers. Pharmacological and non-pharmacological management of dementia depends to a large extent on the presence of BPSD. A committee of geriatricians, neurologists and psychiatrists specialized in dementia (THEMA 2) has promoted an epidemiological, diagnostic and therapeutic update in this field. This work was based on the BPSD Consensus Conference Report edited in 2000 by the International Psychogeriatric Association. This report was updated with the most recent literature reports, and was adapted to the French environment. This paper is a synthesis of this meeting, validated and corrected by the entire Thema 2 group.

Aged↗
PubMed2002

["The 5 words": a simple and sensitive test for the diagnosis of Alzheimer's disease].

OBJECTIVE: Alzheimer's disease (AD) is under-diagnosed in France. Today only an estimated 50% of patients are identified. Diagnosis of AD is particularly difficult because the amnesic syndrome, characteristic of the disease, is often confused with memory dysfunction that is frequent during the process of aging. The improvement in the diagnostic conditions of AD relies on the availability of a simple and reliable tool for screening memory disorders of organic origin. METHOD: The 5-word test studies the recall of a short list, which the physician ensures the patient has registered. Its construction permits the identification of patients exhibiting objective memory disorders. A validation study has been conducted in 86 patients suffering from AD and 126 persons complaining of functional memory disorders. RESULTS: The study has shown the sensitivity (91%) and specificity (87%) of the 5-word test in identifying patients with AD. CONCLUSION: This is a rapid (2 minutes) and simple test that is easy to use in medical practice for the screening of AD.

Age Factors↗
PubMed2002

[REM Sleep behavioral disorder].

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia which occurs only during REM sleep. RBD is characterized by the loss of skeletal muscle atonia, which is the principal feature of REM sleep, and by abnormal behavior representing the attempted enactment of dreaming. Clinically, it consists of abnormal behavior, frequently violent, that may lead to injuries. A polysomnographic study is necessary to assess the diagnosis showing the absence of REM sleep atonia and related abnormal behavior. RBD usually affects older men. Its exact etiological factors remain unknown. However, RBD is sometimes linked with drug use or exposure to toxic conditions. Moreover, the association with neurological disorders is frequently reported, particularly cerebrovascular, tumoral or neurodegenerative disease. Neurodegenerative disorders with parkinsonism are frequently involved. In Lewy body dementia, RBD is particularly frequent. In many cases, RBD may have a predictive value, preceding other symptoms of neurodegenerative disorders with parkinsonism. The biochemical mechanisms underlying RBD still remain unclear but could involve the dopamino-cholinergic balance and the serotoninergic pathway.

Anticonvulsants↗
PubMed2002

[Mild cognitive impairment: imaging data].

The diagnosis of Mild Cognitive Impairment (MCI) as defined by Petersen et al. (1997), is based uniquely on clinical observations. Cerebral imaging, both morphological and functional, may in fact facilitate diagnosis, particularly with regard to the differentiation of sub-types of MCI and the identification of prodromal AD (MCI-AD). Volumetric Magnetic Resonance Imagery (MRI) examination of structures affected early in AD such as entorhinal cortex, the temporal lobe and, above all, the hippocampus, are especially useful. Hypoactivity within these regions, especially of the temporal lobe and posterior cingulate gyrus by Positon Emission Tomography, and more recently monophotonic emission tomoscintigraphy, also appears to have diagnostic utility. Studies of cholinergic system activity by functional imaging may also be of future value in MCI-AD diagnosis. MRI used in conjunction with other techniques may be of significant value, in particular the use of spectro-MRI and functional MRI. This latter technique, leading to the development of cognitive activation paradigms, is particularly promising.

Aged↗
PubMed2001

Cognitive impairment in motor neuron disease with bulbar onset.

METHODS: Twenty-three patients with bulbar onset motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) were clinically assessed. They subsequently underwent serial neuropsychological testing, event-related potentials (ERP) and SPECT studies. Cognitive impairment was defined by clinical evidence of dementia (DSM-IV and frontal evaluation) or by significant alteration indicated by neuropsychological testing (excluding patients with depression and major anxiety), or both. RESULTS: Eleven patients (48%) were found to be cognitively impaired. Abnormalities indicated fronto-temporal involvement, with memory impairment, alteration of judgement and reasoning, reduced speech, behavioural dyscontrol and alteration of daily living activities. This impairment correlated well with event-related potentials and SPECT studies. Event-related potentials were the most sensitive test as 100% of the impaired patients had abnormal ERP (p = 0.04). The cognitively impaired group differed from the other group mainly by gender ratio (male/female) with an important male predominance: 1.75 vs. 0.33. MND/ALS was also more severe when cognitive decline was present. CONCLUSION: This study adds further arguments for a cognitive impairment in MND/ALS. This also reinforces the hypothesis that there is continuum between MND/ALS and fronto-temporal lobe dementia.

Activities of Daily Living↗
PubMed1998

Polydispersity of a Non-ionic Surfactant as Related to Its Adsorption Characteristics on Porous Silica Particles in Water.

The effect of particle porosity on the adsorption of the oligomers of a polydispersed non-ionic surfactant of the alkylpolyoxyethylene series has been investigated at a silica/water interface using a HPLC technique. This surfactant displayed a high degree of polydispersity relative both to alkyl chains and to polar chains. The results obtained are compared to previously determined adsorption isotherms for the same surfactant on a nonporous silica. It is observed that qualitatively, the shape of the isotherms are similar on both silicas with minor differences below the adsorption plateaus. However, quantitatively, the adsorption density is about four times lower on the porous material as compared to the nonporous one. These findings are interpreted using available information on the porosity and on the size of the primary particles. The composition of the adsorbed micellar-like aggregates is shown to be independent upon the structure of the surface particles. Preferential adsorption of the oligomers with the shorter ethoxychains is displayed on both silicas. The polydispersed surfactant used did not follow a Poisson distribution with respect to the ethoxychains and the presence of polydispersed alkyl chains did not influence the shape of the polar chains distribution. Copyright 1998 Academic Press.

Journal Article↗
PubMed1997

Adsorption Isotherms at a Silica/Water Interface of the Oligomers of Polydispersed Nonionic Surfactants of the Alkylpolyoxyethylated Series

Adsorption isotherms of the oligomers of three commercial alkylethoxylated nonionic surfactants at a silica/water interface have been determined using a HPLC method. The surfactants investigated are of the type used in detergency. The compounds, here noted A, B, and C, were mixtures of surfactants. A and B were of the general formulas C13E7 + C15E7 and C13E10 + C15E10, respectively. Compound C was a mixture of oligomers ranging from C12E7 to C16E7 in various proportions. About 10 isotherms are presented for the most important oligomers for each of these detergents. Compound C could be more thoroughly discussed than compounds A and B because adsorption data for the pure surfactant of the same surfactant series with even numbers of carbon atoms in the alkyl chain were made available. Thus, the behavior of representative oligomers of C could be compared with that of the same pure surfactants at the silica/water interface. It is shown that at low surface coverage, polydispersity effects of either alkyl chains or ethoxy groups on global surfactant adsorption are negligible and the oligomers behave essentially as pure, single surfactants. At higher surface coverage, the simultaneous presence of oligomers with long chain lengths or with small numbers of ethoxy groups does not favor the formation of large structures, disks, or patched bilayers at the silica surface as do single pure surfactants. However, it is demonstrated that the opposing effects of oligomers with small and large alkyl chain lengths cancel out in the global isotherms. So it may be concluded that polydispersity in the case of commercial nonionic surfactants of the type used in the present investigation does not affect to any great extent the behavior of such compounds at a silica/water interface. The consequences of these findings can be extended to other nonionic surfactant series. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Adsorption of Pure Nonionic Alkylethoxylated Surfactants down to Low Concentrations at a Silica/Water Interface as Determined Using a HPLC Technique

The adsorption of pure nonionic alkylethoxylated surfactants of the C12 En series at silica/water interface has been determined using a very precise HPLC technique. The number of ethoxylated groups was varied from 2 to 9. The adsorption isotherms were constructed with special attention to the very low surface coverage domain. It is shown that at very low concentration, the adsorption amounts are higher as the number of ethoxylated groups increases but the reverse trend is found at higher surfactant concentration and above the critical micelle concentration. It is shown that this behavior is the consequence of the interplay of the primary and secondary adsorption mechanisms depending upon the length of the ethoxylated chain. The maximum adsorption quantities is not a linear function of the number of ethoxylated groups. This and other observations confirm the viewpoint that the behavior of nonionic surfactant aggregates adsorbed at a hydrophilic surface carries many similarities with the properties of this class of nonionic surfactant aggregates in bulk aqueous solutions.

Journal Article↗
PubMed1996

Nonideality of Mixtures of Pure Nonionic Surfactants Both in Solution and at Silica/Water Interfaces

The behavior of two pure alkylethoxylated nonionic surfactants, both as single components and as binary mixtures of various composition, has been studied in solution and at silica/water interfaces. In solution, the variation of cmc with surfactant composition showed large negative and positive deviations from thermodynamic ideality. These results, as obtained from surface tension measurements, may be interpreted by a partial demixing of the micelles into segregated aggregates in the C10E6-rich composition range and by an increased stability of the aggregates in the C14E6-rich domain. Careful determination of individual isotherms of the surfactants either as single components or as components of mixtures was performed at a nonporous silica/water interface using a reversed phase HPLC technique. The pure nonionic surfactants displayed non superimposable isotherms when sufficiently dilute solution can be attained: a single adsorption plateau is observed with the more hydrophobic component, and a two-plateau behavior is obtained with the more hydrophilic compound. Some experiments with the intermediate surfactant C12E6 were also performed showing a single-plateau profile. Experimental confirmation of the demixing process at the silica/water interface was found in the C10E6-rich end of the diagram. However, the larger than usual favorable interaction between the surfactants in the C14E6-end of the diagram could not be deduced directly from the shape of the individual isotherms. The various isotherms were discussed making use of the known properties of these surfactants in solution as micelle-type aggregates and as lamellar phases.

Journal Article↗