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Biomedical subjects

C Colin

Publications and source records attributed to C Colin.

At least 91 records · Page 5Linked to original sources
PubMed1997

Gene transfer to the central nervous system by transplantation of cerebral endothelial cells.

A cerebral endothelial immortalized cell line was used in transplantation experiments to deliver gene products to the adult rat brain. Survival of grafted cells was observed for at least 1 year, without any sign of tumor formation. When genetically modified to express bacterial beta-galactosidase and transplanted into the striatum, these cells were shown, by light and electron microscope analysis, to integrate into the host brain parenchyma and microvasculature. Following implantation into the striatum and nucleus basalis of adult rats, endothelial cells engineered to secrete mouse beta-nerve growth factor (NGF) induced the formation of a dense network of low-affinity NGF receptor-expressing fibers near the implantation sites. This biological response was observed from 3 to 8 weeks after engraftment. The present study establishes the cerebral endothelial cell as an efficient vector for gene transfer to the central nervous system.

Animals↗
PubMed1997

Vitamin C supplementation does not modify bone mineral content or mineral absorption in growing pigs.

We have demonstrated that alkaline phosphatase activity and collagen synthesis are dose-dependently stimulated by ascorbic acid in differentiated pig osteoblasts. In this study we further examined the relationship between ascorbic acid and bone metabolism by feeding young pigs large amounts of ascorbic acid. Three groups of seven 47-d-old pigs were given no ascorbic acid supplement (control), 500 (500 AA) or 1000 (1000 AA) mg ascorbic acid/kg diet for 4 mo. Calcium and P absorption and retention were evaluated by a 14-d balance trial immediately before killing in control and 1000 AA groups only (n = 6). Bones were collected at death and the bone ash and bending moment (three-point bending test) determined. Various plasma and urine indices of bone metabolism, especially those reflecting collagen degradation (hydroxyproline, deoxypyridinoline) and synthesis (carboxyterminal propeptide of type I collagen) were monitored. The plasma ascorbic acid concentrations increased with time and paralleled the dietary concentrations (P < 0.01). The Ca and P balances and the bone ash and bending moments in the ascorbic acid-supplemented pigs did not differ from those of the controls. Plasma osteocalcin was elevated (P < 0.05), whereas the other bone formation markers, alkaline phosphatase and carboxy terminal propeptide of type I collagen, were not affected by ascorbic acid. The plasma concentrations of Ca, P and 1,25-dihydroxycholecalciferol did not differ among the three groups. The unaffected urinary excretion of deoxypyridinoline and hydroxyproline in the ascorbic acid-supplemented pigs indicates that ascorbic acid does not alter bone resorption. Thus, high intakes of ascorbic acid have no positive influence on bone metabolism and bone characteristics in pigs. The in vivo long-term effects do not correlate with the short-term in vitro effects previously reported.

Absorption↗
PubMed1996

Immobilized metal ion affinity gel electrophoresis: quantification of protein affinity to transition metal chelates.

This paper describes some recent advances in the methodology of immobilized metal ion affinity gel electrophoresis. Four different ways to incorporate metal chelate ligands in agarose and polyacrylamide-based electrophoresis gels are evaluated, a new polymerizable metal chelating ligand, allyl-2-hydroxy-3-(N,N-dicarboxymethyl)amino-propyl ether, is introduced, and the determination of affinity constants described. The affinities of model proteins (ribonucleases A and B and cytochromes c from different species) for the transition metal chelate iminodiacetic acid-Cu(II) were studied. The results were found to be in agreement with literature data on immobilized metal ion affinity chromatography, and the polymer nature and the different chemistries used influenced the affinity only quantitatively, keeping the basic mechanisms of interaction unchanged.

Animals↗
PubMed1996

[Perioperative artificial nutrition in elective surgery. A descriptive study of practice patterns in France].

OBJECTIVE: To analyse the practice patterns of perioperative artificial nutrition in France before the Consensus Conference held on 16 december 1994 and to compare them with the recommendations produced by this Conference. STUDY DESIGN: Retrospective cross-sectional practice patterns study. PATIENTS: Sample of patients collected from general or digestive tract surgeons, including for each one the last two patients having had before 10 December 1994 either elective upper (oesophagectomy, duodenopancreatectomy) or elective lower (colectomy) abdominal surgery. The response rate to the 2, 150 circulated questionnaires was 14% (309), producing a sample of 601 patients (49% with upper abdominal surgery, 51% with lower abdominal surgery). RESULTS: The geographical distribution of surgeons who replied and their type of activity (private or public) was similar to the national pattern, however with some underrepresentation of the larger Paris area. The duration of pre- or postoperative artificial nutrition was bellow seven days in 36% of the cases, and above this delay in 64% of the cases. Artificial feeding rates for upper abdominal surgery, were 9 and 75%, respectively (duration of artificial feeding of 7 days and more being only considered). For lower abdominal surgery, these rates were 5 and 41%, respectively. Enteral nutrition was given in 13% of preoperative cases and 19% of postoperative ones; the others received parenteral nutrition. When compared to the recommendations by the Consensus Conference, these results show an insufficient use of preoperative artificial nutrition in patients with malnutrition (only 22% of them received it) and an excessive use in postoperative patients, particularly after lower abdominal surgery. Furthermore, the caloric intake was in accordance with the recommendations in only 20% of the cases. It was too high in 38% of the cases and insufficient in 47% of them. Similarly, the postoperative nitrogen intake complied with the recommended figures in only 5% of the cases. CONCLUSION: This study highlights large discrepancies between the recommendations by the Consensus Conference and current practice patterns. It questions the efficiency of this therapy as it is implemented today and generates high and unwarranted expenses.

Digestive System Diseases↗
PubMed1996

[Decision analysis of congenital toxoplasmosis in the absence of exact knowledge of the treatment benefits and secondary effects].

Decision analysis seemed the appropriate method to bring out the interest of toxoplasmosis serology in children born from mothers who seroconverted during pregnancy. In particular it provides the possibility to choose between IgA serology, recently introduced in hospital practice, and IgM serology that is the reference test. We study a series of 96 children suspected of having congenital toxoplasmosis who were followed up until the age of one. A decision analysis is thereafter conducted by synthesizing data about clinical efficacy with the RBNCN ratio that is the net benefit of treating an affected person divided by the net cost of treating an unaffected person; these costs and benefits are clinical. The effectiveness of the treatment (sulphonamides in most cases) was not quantified. Therefore, we used the fact that the RBNCN ratio is equal to the number of healthy children likely to be treated unnecessarily in order not to leave untreated a contaminated child. Although data available in the literature and data from our study still remain insufficient to draw a final conclusion, IgA antibodies are significantly more sensitive than IgM antibodies (p < 0.01). Conversely, IgA antibodies are significantly less specific than IgM antibodies (p < 0.001). The sensitivity analysis shows that the IgA test is preferred to the IgM test if the mother is contaminated during the third trimester. On the other hand, for low prevalences, as observed in the first trimester, the IgM serology is more useful.

Anti-Infective Agents↗
PubMed1996

[Medical and economic evaluation of donated blood screening for hepatitis C and non-A, non-B, non-C hepatitis].

The aim of this study was to evaluate the cost of hepatitis C and non-A non-B non-C screening strategy in donated blood, currently used in French transfusion centres and to assess the effect in the blood transfusion centres according to the prevalence of the disease and the intrinsec values of tests. This screening strategy was based on alanine aminotransferase assay, and HBc and HCV antibodies detection. In 1993, a survey was conducted in 26 French transfusion centers to estimate the costs of the screening strategy currently used. Average expenditure on diagnostic sets, equipment, staff and administration charges for hepatitis C and non-A non-B non-C screening were calculated. From these results, we estimated the cost of the previous strategy which did not involve HCV antibody testing, so as to determine the incremental cost between the two strategies. We used clinical decision analysis and sensitivity analysis to estimate the incremental cost-effectiveness ratio with data gathered from the literature and examine the impact on blood transfusion centre. Implemented for 100,000 volunteer blood donations, the incremental cost of the new strategy was FF 2,566,111 (1992) and the marginal effectiveness was 180 additional infected donations detected. The sensitivity analysis showed the major influence of infection prevalence in donated blood on the incremental cost-effectiveness ratio: the lower the prevalence, the higher the cost-effectiveness ratio per contaminated blood product avoided.

Adult↗
PubMed1996

[Hierarchy of breast examinations after twenty years experience].

OBJECTIVE: To reassess the interest to establish a qualitative hierarchy of explorations for breast lesion diagnosis. MATERIALS AND METHODS: The medical files stored on perforated cards concerning 6866 patients examined in our breast disease clinic from 1974 to 1976 was compared to the computerized medical files of 14747 patients followed in the same clinic from 1990 to 1992. The hierarchy took into account, by decreasing order of importance, the significant results of cytology and radiography, clinical examination and finally thermography for the 1974-1976 patients and ultrasonography for the 1990-1992 patients. RESULTS: Comparing the two groups of patients showed a stabilization of the number of cancers (100%) among the diagnoses positive for malignant lesions and of the number of benign lesions (16%) among the lesions evaluate as suspect of malignancy. There was an increase in the cancers (13%) among lesions evaluated as dubious and a decrease in the numbers of cancers (0.1%) among the lesions evaluated as benign. These improvement resulted from technical advance in mammography and the routine use of ultrasonography. CONCLUSIONS: These findings confirm the importance of cytological and radiological exams for the diagnosis of breast cancer and points out the interest of routine ultrasonography of the breast.

Biopsy↗
PubMed1995

Mineral bioavailability and bone mineral contents in pigs given calcium carbonate postprandially.

We have further investigated the "meal effect" on mineral bioavailability in pigs by mineral balance studies and measurements of bone ash contents and bending moment. A group of seven pigs (CAA) was given all its dietary Ca as CaCO3 5 h after the first daily meal for 8 weeks. The control group of seven pigs received CaCO3 in the meal. Both groups were given normal P within the meals. Ca and P absorption and retention were evaluated by a 10-day balance trial. Several bones were collected at slaughter to determine bone ash, Ca, and P contents and bending moment (three-point bending test). Ingesting Ca after the meal did not affect Ca bioavailability or phosphorus absorption, but did reduce P retention, which in turn decreased the bone scores. Osteopenia, indicated by decreased total mineral contents of bones (and decreased ash:bone volume ratio), was associated with elevated plasma osteocalcin in the CAA group. Thus, CaCO3 need not be incorporated into a meal for high Ca absorption, provided that Ca is given after a meal, but simultaneous intakes of Ca and P are required for the best mineral retention.

Absorption↗
PubMed1995

Fine structure of astroglial integration into host brain following xenografting.

Previous investigations showed that fragments of fetal rabbit brain transplanted into striatum of neonatal shiverer mouse give rise to cells that migrate through host tissue and differentiate into astroglia and oligodendroglia within 2 weeks. We studied the integration of transplanted astroglia at the ultrastructural level using pre-embedding labeling with a monoclonal antibody which recognizes an epitope associated with rabbit but not mouse glial fibrillary acidic protein. The morphology of early migrating donor cells does not distinguish them from cells arising in host germinal matrix. Once the cells complete their migration they integrate into host brain in a structurally normal manner. Transplanted astroglia form perivascular foot plates with host capillaries. They also send extensive processes into the neuropil where intimate contacts with neurons and synaptic structures are formed. Oligodendroglia send processes to nearby axons where they form normal-appearing myelin. During the rejection process, which may begin at 4 weeks, donor astroglia show evidence of reaction with increased intermediate filament content. Donor cells are attacked by leukocytes, including eosinophils, and subsequently degenerate. We conclude that cross-species transplantation of glial cells can result in entirely normal structural integration into host brain.

Animals↗