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M Pressac

Publications and source records attributed to M Pressac.

31 records · Page 2Linked to original sources
PubMed1987

[Reference values of serum transferrin in newborn infants, children and adults].

The authors have studied the evolution of serum transferrin concentration in relation with age (newborn child, infant, adult). The mean concentration of serum transferrin is the lowest for neonates (2.15 g/l). At 10 months, it increases to reach a value of about 3.10 g/l then reduces at 24 (3.0 g/l) and 48 months (2.8 g/l). By the 4 to 18 years subjects, serum transferrin is approaching that of 10 months children (3.15 g/l). At last it doesn't support any modification during all the adult life. The diversity of the obtained results dependent of the used technique and/or of the laboratory, justifies that each one defines his own reference values.

Adolescent↗
PubMed1986

Further evidence that thyrotropin-releasing hormone participate in the regulation of growth hormone secretion in the rat.

Effects of thyrotropin-releasing hormone (TRH) on growth hormone (GH) secretion were investigated in vivo (on intact or mediobasal hypothalamic lesioned rats tested under either anesthesia or free moving conditions) as well as in vitro (in incubation or perifusion systems of anterior pituitary tissue). The peptide induced a rapid, dose-dependent increase of plasma GH levels in free moving animals bearing an extensive lesion of the mediobasal hypothalamus including the median eminence. Under comparable conditions, TRH was ineffective in intact animals. After chloral hydrate anesthesia a GH response to TRH was recorded in both groups, but lesioned rats exhibited a better responsiveness to all doses tested. In vitro TRH increased GH release from incubated or perifused pituitaries sampled from both intact and lesioned rats in a transient and concentration-dependent manner. A similar effect was obtained with the (3 Me His2) analogue of TRH. These findings indicate that TRH can affect GH secretion at the pituitary level under specific experimental conditions and support the hypothesis that either peripheral hormones or other, still unidentified hypothalamic neurohormones may modulate this effect.

Anesthesia, General↗
PubMed1986

Concurrent immunoassay of C-reactive protein and orosomucoid by random-access analysis.

We describe turbidimetric methods for simultaneously determining C-reactive protein and orosomucoid in 33 microL of undiluted serum in the Technicon RA-1000, with multipoint calibration. Precision is good and results correlate favorably with those of nephelometry with the Beckman ICS (r = 0.98 for CRP, 0.99 for orosomucoid). Analyses are easy to perform, require infrequent calibration, and are suitable for routine and emergency analysis.

Autoanalysis↗
PubMed1983

[Adaptation of IgG, IgA, and IgM determination on the Isamat: a turbidimetric method].

We have adapted the turbidimetric assay of immunoglobulins IgG, IgA and IgM to a transfer analyser: Isamat. This reaction takes place in the presence of PEG and the reading is made at 340 nm. The repeatability and reproducibility are satisfactory with a variation coefficient of 2.9% to 7.2%. The correlation with the kinetic method (ICS Beckman) is excellent for IgG and IgA and good for IgM. The protocol established enables eleven assays of three different proteins in one hour. The reduced requirement for pure antiserum and the low sample volume (5 to 10 microliters) make this turbidimetric technique useful in pediatrics.

Autoanalysis↗
PubMedDate not supplied

[Tamm-Horsfall protein].

Human Tamm-Horsfall glycoprotein, the major urinary protein, is a glycosyl-phosphatidyl-inositol (GPI) - anchored membrane protein which mainly resides at the luminal face of cells of the thick ascending limb of Henle's loop (TAL) and early distal convoluted tubules of nephron. Tamm-Horsfall protein contains exclusively N-linked glycans, mainly of polyantennary type largely sialylated and fucosylated, but also high-mannose glycans. Only a portion of the Tamm-Horsfall protein is released as soluble protein by the action of proteases and in a minor amount by a cell-associated GPI-specific phospholipase. The physiological function of Tamm-Horsfall glycoprotein has not been clarified to date. Since the urinary Tamm-Horsfall protein has a high gel-forming tendency, it has been postulated that it takes part in the water impermeability of TAL. It is also proposed that the Tamm-Horsfall protein plays a protective role towards pyelonephritogenic pathogens such as Escherichia coli. The Tamm-Horsfall protein may inhibit the colonization of these pathogens in the renal mucosa in that the soluble form competes with that exposed at the plasma membrane. Recently, urinary Tamm-Horsfall protein has been implicated in tubulointerstitial nephritis.

Humans↗
PubMedDate not supplied

[Biochemical markers of bone remodeling: pre-analytical variations and guidelines for their use. SFBC (Société Française de Biologie Clinique) Work Group. Biochemical markers of bone remodeling].

Biochemical markers of bone turnover have been developed over the past 20 years that are more specific for bone tissue than conventional ones such as total alkaline phosphatase and urinary hydroxyproline. They have been widely used in clinical research and in clinical trials of new therapies as secondary end points of treatment efficacy. Most of the interest has been devoted to their use in postmenopausal osteoporosis, a condition characterized by subtle modifications of bone metabolism that cannot be detected readily by conventional markers of bone turnover. Although several recent studies have suggested that biochemical markers may be used for the management of the individual patient in routine clinical practice, this has not been clearly defined and is a matter of debate. Because of the crucial importance to clarify this issue, the Société Francaise de Biologie Clinique prompted an expert committee to summarize the available data and to make recommendations. The following paper includes a review on the biochemical and analytical aspects of the markers of bone formation and resorption and on the sources of variability such as sex, age, menstrual cycle, pregnancy and lactation, physical activity, seasonal variation and effects of diseases and treatments. We will also describe the effects of pre-analytical factors on the measurements of the different markers. Finally based on that review, we will make practical recommendations for the use of these markers in order to minimize the variability of the measurements and improve the clinical interpretation of the data.

Adolescent↗
PubMedDate not supplied

[Prescription of bone remodeling markers in hospitals].

Biochemical markers of bone turnover have for several years been considered as valuable parameters in research clinical studies, but their use in individual patients is still debated. Recently several position papers have proposed guidelines for their use in clinical practice in patients with post menopausal osteoporosis. In the present article, we report the results of a survey which aims at comparing the actual modalities of prescription of French physicians with the above-mentioned recommendations. We contacted by phone clinical chemists from 158 different hospitals and asked them to transmit to the concerned physicians of their hospital a detailed questionnaire for assessing which bone marker(s) is (are) prescribed and for which purpose (s), and if not prescribed, the reason of non prescription. We were able to analyze 309 questionnaires from 89 hospitals including 5 specialties, rheumatology (35.9%), endocrinology (18.1%), gynecology (11.0%), internal medicine (22.0%) and geriatry (12.9%). The results showed large discrepancies between the mode of prescription of a subset of physicians and the guidelines. The most often evoked reason for non prescription was a lack of information about bone markers suggesting a need for teaching courses. This survey has also shown that many physicians do not know exactly which parameters are effectively measured in their hospital and which are addressed to specialized laboratories underlining the importance of the dialogue between clinicians and clinical chemists. We propose that in a given hospital, the present article may serve as a basis for a discussion between clinicians and biologists about the development and/or the optimization of the measurements of these markers of bone turnover.

Biomarkers↗
PubMedDate not supplied

[Improvements from the reference material CRM 470 in the standardization of the determination of serum proteins].

The introduction of the CRM 470 in 1993 (certified reference material for 14 serum proteins) and its utilization by industrial companies for cross-calibrating their commercial standards has been an important break-through in protein standardization. This improvement has been clearly illustrated by the last national quality control survey performed in France in may 1995. At this time, about 60% of the 1,870 participants have already adopted the new standardization. The between-run precision (interlaboratory and intertechnique) has been considerably improved by the use of the new international standard (5.8 to 12.2% versus 10 to 24.1% before standardization); the same is true for accuracy. These results should convince the last reluctant laboratories to adopt the new standardization. Thus, it seems now possible to define reference ranges for serum proteins: this is the new task assigned to the Committee for Plasma Protein Standardization of the IFCC.

Blood Proteins↗