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Biomedical subjects

P Robert

Publications and source records attributed to P Robert.

At least 19 recordsLinked to original sources
PubMed1996

Assessment of qualitative functional parameters of stored red blood cells from donors with sickle cell trait (AS) or with heterozygote (AC) status.

We have compared the storage quality of three groups of 10 red blood cell concentrates of the AA, AS and AC haemoglobin phenotype. The 30 samples were drawn on CPD on day 0, and were centrifuged 6 hours later. Leukocytes were removed on D1 and the samples were kept at +4 degrees C for 42 days in SAG-mannitol. Viability tests were performed using a series of in vitro tests, including: ATP, 2,3-DPG, K+, glucose, lactic acid, pH, osmotic fragility tests and erythrocytic morphology determination. Results demonstrated a good functional quality for AS and AC haemoglobin RBCs. Higher 2,3-DPG levels were found in Hb AS and Hb AC. A lower osmotic fragility in Hb AC and AS RBCs versus Hb AA was observed; no significant difference was found in terms of ATP levels and other parameters. In addition no variation in S and C haemoglobin levels and no sickling were observed. In conclusion, these results indicate an overall good quality for haemoglobin AS and AC RBCs. Further in vivo studies must now be performed in order to confirm the transfusional quality of haemoglobin AS and AC RBCs.

2,3-Diphosphoglycerate↗
PubMed1996

Characterization of a monoclonal antibody reacting with the free human luteinizing hormone beta-subunit.

Measurement of serum luteinizing hormone (hLH) is important for the detection and follow-up of patients with pathological processes of the reproductive axis. Detection of the uncombined form of the beta-subunit of hLH, or free hLH beta, has proved to be of clinical interest in the recognition of gonadotroph adenomas. As no monoclonal antibody specific for the free hLH beta is at present available, we elicited monoclonal antibodies using free hLH beta as an immunogen. An antibody, named BLH01, was selected for its specific binding to the free beta-subunit, and its antibody-binding site was characterized at the molecular level, emphasizing the importance of amino acid residues located between the disulfide-bonded Cys93 and Cys100. This region has been demonstrated as being particularly critical for the specific binding of lutropic hormones to their receptors. Topographic assignment of the epitope recognized by BLH01 was then achieved by cross-matching studies based on a library of antibodies directed to hLH beta, and the location of some epitopes on the three-dimensional model of the beta-subunit is proposed. A two-site immunoassay based on BLH01 as capture antibody was then developed. This assay, using BLH01, may constitute a simple, sensitive and highly specific procedure for assessing the clinical usefulness of measuring free hLH beta, particularly for the diagnosis and follow-up of patients presenting with pituitary adenomas.

Adenoma↗
PubMed1995

Impairment of recognition memory with, but not without, conscious recollection in schizophrenia.

OBJECTIVE: To test the hypothesis that there is a link between the memory deficit associated with schizophrenia and an impairment of consciousness, an experiential approach was used to assess recognition memory and awareness in schizophrenic patients and normal subjects. METHOD: On a recognition memory task with low- and high-frequency words, the schizophrenic (N = 30) and normal (N = 30) subjects gave "remember" responses to recognized items that were accompanied by conscious recollection and "know" responses to items that were recognized on the basis of familiarity without any recollective experience. RESULTS: Schizophrenia selectively impaired recognition based on recollective experience, as measured by "remember" responses, but had no effects on "know" responses. In the comparison group, low-frequency words, relative to high-frequency words, enhanced conscious recollection but not familiarity. The schizophrenic patients did not display the same word-frequency effect. CONCLUSIONS: These results indicate that schizophrenia affects differentially two means of access to the personal past: it impairs recognition memory with, but not without, conscious recollection. They suggest that the impairment of conscious recollection observed in schizophrenic patients could be due to a failure of elaborative processing of information.

Adult↗
PubMed1995

[Efficacy of antidepressants and thymoregulators in the long-term evolution of depression].

Official recommendations pointed out the long term maintenance treatment of recurrent unipolar depression on the basis of a significant effect of antidepressants and mood-stabilizers versus placebo. The results of controlled studies, mainly using imipramine or lithium salts, have not been encouraging in term of long term prognosis, due to the limited success rate for maintenance phase ranging from 30 to 48%. The "Pittsburgh study" maximized the recurrence potential by defining patients selection on at least 3 previous episodes of unipolar depression, with the immediate previous episode being no more than 2.5 years earlier, beginning the experimental maintenance therapy phase after patients remain relatively symptom free for a total of 20 weeks, and scheduled the imipramine withdrawal in the randomly assigned placebo group by a progressive reduction of 33% per week. Survival analysis in the 5 years maintenance outcome of previously imipramine responders patients demonstrated an increased risk of depressive recurrence at the beginning of discontinuation but did not prove a true prophylactic effect. Furthermore these findings do not prove that treatment are not more effective than placebo, suggesting at least a revisitation of the clinical concept of response. The putative efficacy of biological treatment should be an operational criteria to elicit vulnerability markers, mainly in the field of sleep research.

Affect↗
PubMed1995

Citalopram in doses of 20-60 mg is effective in depression relapse prevention: a placebo-controlled 6 month study.

The aim of the present study was to determine whether, in patients with depression who had responded favourably to the selective serotonin reuptake inhibitor citalopram, there was a therapeutic benefit in continuation treatment. Three hundred and ninety-one depressive patients were included in an open short-term citalopram treatment period. Only patients who responded to treatment at 8 weeks (total score of 12 or less on the MADRS scale) were randomized to the 24 week double-blind phase. Seventy-four patients were treated with placebo and 152 with citalopram at the same constant dose to which the patient had responded in the first phase. Relapse was defined as a total score of 25 or more on the MADRS scale. Twenty-one patients (13.8%) continuing to receive citalopram relapsed compared with 18 patients (24.3%) receiving placebo. The log rank test for survival data used to test the quality of relapse hazards between the placebo group and the citalopram group showed that patients treated with citalopram had a significantly lower relapse rate (p = 0.04). The results of this study are in general agreement with those of other studies on antidepressants, and support the hypothesis that full dose continuation is more effective than placebo in preventing relapse of depression.

Adult↗
PubMed1995

Incline, speed, and distance assessment during unconstrained walking.

Body accelerations during human walking were recorded by a portable measuring device. A new method for parameterizing body accelerations and finding the pattern of walking is outlined. Two neural networks were designed to recognize each pattern and estimate the speed and incline of walking. Six subjects performed treadmill walking followed by self-paced walking on an outdoor test circuit involving roads of various inclines. The neural networks were first "trained" by known patterns of treadmill walking. Then the inclines, the speeds, and the distance covered during overground walking (outdoor circuit) were estimated. The results show a good agreement between actual and predicted variables. The standard deviation of estimated incline was less than 2.6% and the maximum of the coefficient of variation of speed estimation is 6%. To the best of our knowledge, these results constitute the first assessment of speed, incline and distance covered during level and slope walking and offer investigators a new tool for assessing levels of outdoor physical activity.

Adult↗
PubMed1994

Cloning and sequencing of the equine testicular follitropin receptor.

To investigate the possibility that specific structural determinants within the equine follitropin receptor (eFSHR) are critical to the enhanced specificity of this receptor compared to other FSHRs, we used the RACE-PCR technique to clone the eFSHR from equine testis. Sequence analysis revealed that the eFSHR is highly homologous to other mammal FSHRs, but it presents 10 unique amino acid residue replacements in the extracellular domain. Furthermore, a potential N-glycosylation site was detected at a position not encountered in other receptors. Northern blot analysis identified three transcripts of 4.2 kb, 2.3 kb and 1.0 kb in horse testis.

Amino Acid Sequence↗
PubMed1994

Conformation changes of beta-lactoglobulin: an ATR infrared spectroscopic study of the effect of pH and ethanol.

Fourier transform infrared spectroscopy has been applied to investigate the secondary structural changes of beta-lactoglobulin in water/ethanol mixtures. The studies were carried out at two different pHs and at high protein concentrations. The spectra were recorded using an attenuated total reflection cell. The amide I band of beta-lactoglobulin in water reveals large amounts of intra extended beta-sheet structure. About 20% ethanol, beta-lactoglobulin unfolds and beta-strand formation is observed. alpha-Helices are built up by increasing the ethanol concentration up to 30%. In 50% ethanol, beta-lactoglobulin gels providing the apparent pH are neutral. The secondary structural changes of beta-lactoglobulin were observed on the similarity maps obtained by Principal Component Analysis.

Animals↗
PubMed1994

Insecticidal and cytotoxic effects of natural and hemisynthetic destruxins.

The insecticidal and cytotoxic effects of 13 natural and hemisynthetic destruxins have been studied. DE shows insecticidal effects similar to those of DA, while DE and DA are more active than all the other natural compounds and analogues tested. Brominated destruxin is a relatively active analogue displaying particular modalities of cytotoxic effects which reflect a certain originality of its mode of action. The linear molecule resulting from the opening of the DA cycle is not toxic. The most hydrophilic destruxins showing e.g. charged radicals (COO-) appear the least toxic probably because they do not penetrate easily the cellular membranes.

Administration, Oral↗
PubMed1994

[Effect of a diet supplemented with soybean oil or fish oil on the reversibility of docosahexaenoic acid deficiency (22:6w3) in the brain and erythrocytes of rats].

This study was undertaken, to evaluate the effects of dietary supplements containing either soybean oil (19:3w3; ALA), or fish oil (22:6w3; DHA), added to the lactating rat dam diet, on the levels of DHA in brain and erythrocytes of DHA deficient pups. Pregnant rats fed omega 3 deficient diets were divided at parturition into three groups. One group was kept on the same diet fed during pregnancy. The two remaining groups received the above mentioned omega 3 supplements. These feeding regimens were maintained during 18 days. Supplementation of diet with 114 mg DHA/100g diet, increased significantly the concentration of DHA in brain and erythrocytes of the suckling rats. In contrast, the effects of the supplementation with ALA (700 mg/100g diet), were limited to the increase of DHA content in the brain. This increase however, was partial, reaching only 50% of the normal. Results suggest that newborn rat has a limited capacity to convert DHA from ALA, becoming dependent of preformed DHA supply to cover DHA requirements at the cellular level.

Analysis of Variance↗
PubMed1993

Expression of the human follicle-stimulating hormone receptor in the baculovirus system.

Human follitropin receptor (hFSHR) cDNA was inserted into the genome of Autographa californica nuclear polyhedrosis virus under the control of the polyhedrin promoter. Spodoptera frugiperda (Sf9) insect cells expressed the hFSHR at the membrane level, 2-3 days after infection. Ligand binding analysis demonstrated saturable, high-affinity binding of 125I-labeled recombinant hFSH (Kd = 0.17 nM) as well as binding specificity for both human and equine FSH. Interestingly, a highly purified preparation of equine choriogonadotropin was found to compete with the binding of 125I-rhFSH. Finally, Western-blot analysis, using a monoclonal antipeptide antibody directed to the 178-206 region of the hFSHR, revealed two bands migrating at M(r) 77 and 130 kDa.

Animals↗
PubMed1993

Real-time measurement of the contribution of the muscular activity to the metabolic rate in freely moving rats.

A new real-time ergometric system, ERGORAT, for measuring the energy expenditure due to muscular activity of small mammals is described. The method is based on measuring the vibrations induced by a freely moving rat to a platform on which it is living. Six accelerometers placed on the platform detect all the vibrations produced by the rat. The co-ordinates of the centre of mass of the animal are located by an optoelectronic device. This location and the six accelerations are fed to a microprocessor-based data acquisition and processing system. Using a Lagrangian dynamic model, the values of the mechanical energy transferred to the platform are computed every second. ERGORAT is used as part of an experimental setup allowing the measurement of the energetic balance of lean and obese rats. The results clearly show that the increase in metabolic rate of obese rats during cold exposure can be entirely explained by the cost of their increase in locomotor activity, whereas for lean rats, this cost accounts for only 41.5 per cent of their metabolic increase, the remaining being the contribution of their active brown adipose tissue.

Animals↗
PubMed1993

Biocompatibility and resorbability of a polylactic acid membrane for periodontal guided tissue regeneration.

The biocompatibility and degradation processes of biomembranes made of a mixture of a high molecular weight racemic polylactic acid (PLA50P) with 0, 10, 20 and 30% w/w racemic polylactic acid oligomers (PLA50p) were assessed for morphological changes in subcutaneous abdominal membrane implantations after 15, 21, 30 and 60 d in 45 Wistar rats. These membranes, prepared for periodontal guided tissue regeneration, showed excellent tissue tolerance without an inflammatory reaction. The higher the content in low molecular weight polylactic acid, the higher the degradation rate. At 60 d, the resorption process was almost complete. This process was initiated by outgrowths of short vascular septa, which developed into lobular networks infiltrating the membranes, which were progressively replaced by normal fibrous connective tissue.

Animals↗
PubMed1992

Trimipramine: acute and lasting effects on sleep in healthy and major depressive subjects.

The acute effects of trimipramine on sleep EEG patterns were investigated in six depressed inpatients and six healthy volunteers. The effects of long-term administration were then assessed in depressed patients after 4 weeks of treatment. Sedative effects of the drug were more pronounced in healthy subjects while sleep parameters of depressed patients seemed less sensitive to the drug. Chronic effects tended to correct most of the sleep disturbances seen in depressed subjects with respect to the natural organization of sleep. The major sleep effect of trimipramine concerned REM latency which was lengthened in both groups, independently of the treatment protocol.

Adult↗
PubMed1992

[Disorders of circadian rhythms in depression].

The authors make a synthesis of studies about circadian rhythms in depression and of hypothesis to explain them. They successively study trials on the phases, on the average levels, on the amplitude of rhythms. They conclude the most significant troubles are, shortening of latency on paradoxical sleep for phases, slump of melatonin levels, blunded amplitude of every parameter. Among possible explanations, they present and discuss a trouble of oscillators, a decrease of sensitivity to external synchronizers and a trouble in rhythm coupling.

Adrenocorticotropic Hormone↗