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P Robert

Publications and source records attributed to P Robert.

At least 37 records · Page 2Linked to original sources
PubMed2000

Gelation by phase separation in a whey protein system: in-situ kinetics of aggregation.

The aggregation and gelation properties of beta-lactoglobulin (BLG), a globular protein from milk, was studied in aqueous ethanol solutions at room temperature. The phase state diagrams as a function of pH and ethanol concentration showed that a gel structure appeared after a period ranging from 1 min to 1 week, depending on the physico-chemical conditions. The in-situ kinetics of aggregation were followed by several methods in order to obtain a better understanding of the building of aggregates by the addition of ethanol. It was shown that the aggregation kinetics highly depended upon the pH, the process being fastest at pH 7. Viscoelasticity and infrared measurements indicated that alcohol-induced gelation would proceed via a two-step mechanism: small aggregates loosely connected between them were first built up; a real network took place in a second step. The coarse and irregular structures formed in aqueous ethanol gels revealed by confocal laser scanning microscopy could be analysed in terms of a phase separation. This observation was supported by a syneresis phenomenon visible in the final gel state. BLG in water-ethanol solution would undergo either an inhibition of the demixing by gelation or a binary phase separation accompanied by an irreversible gelation transition.

Ethanol↗
PubMed2000

Consequences on gonadotrophin secretion of an early discontinuation of gonadotrophin-releasing hormone agonist administration in short-term protocol for in-vitro fertilization.

Administration of gonadotrophin-releasing hormone (GnRHa) agonists, used in IVF short-term protocols to initiate follicular recruitment, may be restricted to the early follicular phase without any further risk of LH surge. However, consequences of an early discontinuation upon residual endogenous gonadotrophin secretion are still unknown. Here, the effects of early cessation of GnRH agonist upon gonadotrophin secretion and ovarian parameters of IVF cycles were investigated. A total of 230 normo-ovulatory women were prospectively allocated to one of the two regimens: decapeptyl-GnRH (100 microgram) was daily injected either from day 1 to the triggering of ovulation (group 1) or for the first 7 days (group 2). Exogenous gonadotrophins (150 IU) were administered on day 4 and 5 with a subsequent adjustment. Detections of free alpha subunit and dimeric LH were performed by highly specific 'two site' monoclonal immunoradiometric assays. The results show that early discontinuation of GnRH agonist administration was associated with a sharp decrease in both plasma free alpha subunit and dimeric LH concentrations while plasma oestradiol response to exogenous gonadotrophins was reduced. Other ovarian parameters and pregnancy rate were unchanged. These data indicate that endogenous LH secretion is maintained by a daily administration of GnRH agonist and may contribute to the final follicular maturation.

Adult↗
PubMed2000

Pharmacokinetics of three gadolinium chelates with different molecular sizes shortly after intravenous injection in rabbits: relevance to MR angiography.

RATIONALE AND OBJECTIVES: To mimic an MR angiographic protocol, an experimental model was developed in rabbits to determine gadolinium concentrations in blood early after injection. Contrast agents with different molecular sizes were compared. METHODS: The influence of injection parameters (injection rate, duration of injection, volume of injection, dose) was assessed, and two blood pool agents (P760, P717) were compared with the low-molecular-weight Gd-DOTA under similar conditions. RESULTS: Two main phases were identified: bolus and post-bolus. Injection parameters strongly influenced the pattern of the bolus phase, but the postbolus phase was sensitive only to the injected dose. The blood pool agents presented a bolus phase profile similar to that of Gd-DOTA, but 45 seconds after injection, 84% of P717 molecules were still present in the blood compartment, compared with 65% of P760 molecules and only 51% of Gd-DOTA molecules. CONCLUSIONS: Blood pool agents are useful for MR angiographic protocols involving the postbolus phase. In protocols in which only the bolus phase is imaged, blood pool agents provide similar data to Gd-DOTA, provided that the injection rate, iso-T1 efficiency dose, and volume are similar.

Animals↗
PubMed2000

[Management of behavioral disorders in dementia patients].

Behavioral disorders are major manifestations of Alzheimer's disease and other forms of dementia. They are associated with caregiver distress, increase the likelihood of institutionalization and may be associated with more rapid cognitive decline. The first step of treatment strategy is an assessment of these disorders. Treatment of behavioral signs is an etiological treatment. Acute behavioral signs are often related to an unknown somatic disease. Chronic signs are often symptoms of the neurological dementia and can be reduced, especially by serotonergic agents and anticonvulsivants. The new antipsychotics are a good alternative to classic neuroleptics known for their frequent cognitive side effects in demented patients. Anticholinesterasic drugs can positively influence noncognitive signs. The treatment of behavioral and psychological symptoms of dementia (BPSD) involves a number of specific interventions including cognitive stimulation which has shown effectiveness on both cognitive functions and quality of life. Prevention of BPSD includes safety measures such as evaluation of suicidality and violence, vigilance regarding neglect and abuse, planning for legal issues due to the patient's incapacity. Families or caregivers should be provided with counseling, education and support. The treatment of BPSD is part of a global and multimodal care which involves general practioners, nurses, social workers, physiotherapists, neuropsychologists, speech therapists, memory centers, psychogeriatric and geriatric units, and respite care units, nursing homes and long-term care facilities. The coordination of the professionals is a critical aspect of providing effective care for patients with Alzheimer's disease.

Alzheimer Disease↗
PubMed2000

[Fatty acids composition and proximate of 7 fish species of Isla de Pascua].

During the last years the study of fatty acids belonging to omega 3 family in marine foods has been emphasized due to their beneficial effects on cardiovascular diseases, which are the main cause of death in occidental countries, as described by literature. In order to obtain more information about the fatty acid composition of the main marine species fat constituent, usually consumed by Eastern Island population, seven fish species were analyzed: Maito (Acanthurus leucopareius), Matuko (Bodianus vulpinus), Marau (Myripristis tiki), Nanue (Kiphosus bigibus). Moki (Mori and Marari, Anampses caeruleopunctatus), Puia (Girellops nebulosus) and Raea (Cheilodactilus plessisi). Fatty acid profile and proximate analysis were determined for each species. According to its fat content, Nanue and Marari showed the highest lipid percentage, with values of 2.8 and 3.6% respectively. Fatty acid profile expressed as methyl esters percentage indicated that the most important group was that of the saturated fatty acids (SFA 35.1-54%), followed by the polyunsaturated fatty acids group (PUFA, 22-42.5%). Palmitic acid was the most important between saturated fatty acids, while oleic acid was the main fatty acid between the monounsaturated group. In omega-3 family fatty acids, eicosapentaenoic acid (EPA, C20:5w3) and docosahexaenoic acid (DHA, C22:6w3) were the most important, with values in a range between 2.0-12% and 1.8-18.3%, respectively. Omega-6 family showed a higher content in arachidonic acid (AA, C20:4w6) with values between 1.9 and 10%. Considering the fatty acid composition and the fat content, Marari was the highest in w-3 and w-6 fatty acid contribution, with values of 850 and 240 mg per one hundred grams of edible portion respectively.

Animals↗
PubMed1999

Identification and characterization of cvHsp. A novel human small stress protein selectively expressed in cardiovascular and insulin-sensitive tissues.

Starting with computational tools that search for tissue-selective expression of assembled expressed sequenced tags, we have identified by focusing on heart libraries a novel small stress protein of 170 amino acids that we named cvHsp. cvHsp was found as being computationally selectively and highly (0.3% of the total RNA) expressed in human heart. The cvHsp gene mapped to 1p36.23-p34.3 between markers D1S434 and D1S507. The expression of cvHsp was analyzed with RNA dot, Northern blots, or reverse transcription-polymerase chain reaction: expression was high in heart, medium in skeletal muscle, and low in aorta or adipose tissues. In the heart of rat models of cardiac pathologies, cvHsp mRNA expression was either unchanged (spontaneous hypertension), up-regulated (right ventricular hypertrophy induced by monocrotaline treatment), or down-regulated (left ventricular hypertrophy following aortic banding). In obese Zucker rats, cvHsp mRNA was increased in skeletal muscle, brown, and white adipose tissues but remained unchanged in the heart. Western blot analysis using antipeptide polyclonal antibodies revealed two specific bands at 23 and 25 kDa for cvHsp in human heart. cvHsp interacted in both yeast two-hybrid and immunoprecipitation experiments with alpha-filamin or actin-binding protein 280. Within cvHsp, amino acid residues 56-119 were shown to be important for its specific interaction with the C-terminal tail of alpha-filamin.

Amino Acid Sequence↗
PubMed1999

Physical activity monitoring based on accelerometry: validation and comparison with video observation.

The objective of this feasibility study is to evaluate the use of the 'Physilog' device, an ambulatory physical-activity recorder based on acceleration measurement, for the monitoring of daily physical activities. Accelerations measured at the level of the chest and the thigh are recorded by Physilog over a period of 1 h in five normal subjects. A specially designed studio-like room allowing the performance of most usual activities of everyday life is used. A video film synchronised with the Physilog is obtained for each subject to check the accuracy of the data derived from Physilog. Based on the analysis on the average and the deviation of the acceleration signal, an algorithm is developed to classify the activities in four categories, i.e. lying, sitting, standing and locomotion. Compared with the video observations, the results from the algorithm show an overall misclassification of 10.7%, which is mainly due to confusion between dynamic activities and the standing posture. In contrast, the misclassification between postures is negligible. It is concluded that Physilog can be used in the clinical setting for the reliable measurement and long-term recording of most usual physical activities.

Activities of Daily Living↗
PubMed1999

Temporal feature estimation during walking using miniature accelerometers: an analysis of gait improvement after hip arthroplasty.

A new method for the detection of gait cycle phases using only two miniature accelerometers together with a light, portable digital recorder is proposed. Each subject is asked to walk on a walkway at his/her own preferred speed. Gait analysis was performed using an original method of computing the values of temporal parameters from accelerometer signals. First, to validate the accelerometric method, measurements are taken on a group of healthy subjects. No significant differences are observed between the results thus obtained and those from pressure sensors attached under the foot. Then, measurements using only accelerometers are performed on a group of 12 patients with unilateral hip osteo-arthritis. The gait analysis is carried out just before hip arthroplasty and again, three, six and nine months afterwards. A mean decrease of 88% of asymmetry of stance time and especially a mean decrease of 250% of asymmetry of double support time are observed, nine months after the operation. These results confirm the validity of the proposed method for healthy subjects and its efficiency for functional evaluation of gait improvement after arthroplasty.

Acceleration↗
PubMed1999

Structural investigation of beta-lactoglobulin gelation in ethanol/water solutions.

The aggregation and gelation properties of beta-lactoglobulin (BLG), a globular protein from milk, was studied in hydro-ethanolic solutions (50/50% (v/v)) at room temperature. The phase state diagrams as a function of pH and ethanol concentration showed that a gel structure appeared after a period ranging from 1 min to 1 week depending on the physico-chemical conditions. The aggregation kinetics, studied by infrared spectroscopy and dynamical rheological measurements, highly depended upon the pH; the process being the fastest at pH 7. Alcohol-induced aggregation of BLG was characterized by the formation of intermolecular hydrogen bonded beta-sheet structures. Small angle neutron scattering indicated that the aggregates structures in the final gels were similar at pH 7, 8 and 9. Through the data obtained at the molecular and macroscopic levels, it can be concluded that the kinetics of gelation were pH dependent while the spatial arrangements of the aggregates were similar in the final structures. The heterogeneous structures formed in hydro-ethanolic gels could be analysed in terms of a phase separation, the syneresis being the final visible state.

Ethanol↗
PubMed1999

Impairment of consciously controlled use of memory in schizophrenia.

Recent studies of memory in schizophrenia have shown that explicit but not implicit memory performance is impaired. The hypothesis that schizophrenia is associated with a failure of consciously but not unconsciously (automatic) controlled influence of memory on performance was tested using a procedure providing uncontaminated estimates of consciously controlled and automatic memory processes (i.e., the process-dissociation procedure in a stem completion task). Performance of 35 patients with schizophrenia was compared with that of 35 normal participants. Consciously controlled use but not automatic influences of memory was significantly lower in patients with schizophrenia than in controls. Consciously controlled use of memory was negatively and significantly correlated with positive symptoms of schizophrenia. Schizophrenia differentially affects 2 types of memory processes: It impairs consciously controlled use of memory but spares automatic influences. Positive symptoms could reflect the lack of control from higher level conscious processes.

Adult↗
PubMed1998

High-level secretion of biologically active recombinant porcine follicle-stimulating hormone by the methylotrophic yeast Pichia pastoris.

An active recombinant glycoprotein hormone, porcine follicle-stimulating hormone (recFSH), has been produced for the first time in the methylotrophic yeast, Pichia pastoris. The yield of secreted recFSH (10 mg/l) was the highest ever reached. RecFSH displayed an apparent molecular mass of 41 kDa by SDS-PAGE and was found to bear only N-linked carbohydrates of the high-mannose type. Its in vitro binding and cell-stimulating activities were identical to those of pituitary porcine FSH. The large availability and the noncharged N-glycans of FSHrec should render it highly valuable for structural studies.

Animals↗
PubMed1998

Characterization of human lutropin carboxyl-terminus isoforms.

Human lutropin (hLH) exhibits both carbohydrate and peptidic heterogeneities that affect its biological potency and the duration of its activity in vivo. Peptidic changes within the hLH beta-subunit are characterized as intrachain proteolytic nicking and carboxyl terminus heterogeneity. To date, the carboxyl terminus of hLHbeta appears to end at either position Gln114 or Gly117, as determined by sequencing of purified subunit. Furthermore, the complementary DNA for hLHbeta predicts a protein containing an additional peptidic stretch, which would make the beta-subunit 121 residues long. This extension may be responsible for the particular intracellular behavior of hLHbeta. To investigate the carboxyl terminus polymorphism of natural hLHbeta, monoclonal antipeptide antibodies were raised against a synthetic peptide mimicking the 104-119 portion of hLHbeta. One antibody, designated LHP09, was found to specifically react with the recombinant hLHbeta ending at position hLHbeta[Leu119] but not with other recombinant forms ending at [Ser116], [Phe120] or [Leu121]. Immunochemical analysis of hLH, either pituitary or urinary in origin, indicated that only pituitary hLH contains a Leu119-ending form of hLHbeta. Finally, immunohistochemical detection was performed using LHP09 and showed specific staining of a normal adult pituitary gland. These observations support the in vivo existence of intrapituitary molecular forms of hLHbeta ending at various positions between Gln114 and Leu121.

Amino Acid Sequence↗
PubMed1998

[Consensus statement of an interdisciplinary group of French experts on modalities of diagnosis and medical treatment of Alzheimer's disease at a treatable stage].

A group of French expert met on the 7th and 8th of February 1998 in order to establish a consensus attitude for Alzheimer's disease diagnosis and treatment. Members were drawn from primary care, geriatrics, neurology and psychiatry. They used the consensus statement of the American Association for Geriatrics, the Alzheimer's Association and the American Geriatrics Society published in JAMA, in October 1997 as a source of data for further consideration. Alzheimer's disease in the most common etiology of dementia. Main clinical features are cognitive impairment and psycho-behavioral disorders. Diagnosis must be one of inclusion and not exclusion. It is based on interviews of informants and family members and office-based clinical assessment. After a physical examination, cognitive function must be evaluated using the Mini-Mental State Examination. A laboratory evaluation should include a complete blood cell count, blood chemistry and determination of thyroid-stimulating hormone. In addition, noncontrast computed tomography head scans are adequate in most cases. Available pharmacologic treatments are not curative but are given to improve quality of life and enhance cognition and behavior. Two cholinesterases inhibitors, tacrine and donepezil, are the only agents officially authorized for treatment of the cognitive impairment in Alzheimer's disease. Mood and behaviour disorder also have to be treated by both pharmacologic and nonpharmacologic strategies. Only pharmacologic treatments will be detailed here. The consensus statements established by this group of experts will be reevaluated each year, considering the new available data on Alzheimer's disease.

Aged↗