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Biomedical subjects

C Gosselin

Publications and source records attributed to C Gosselin.

At least 19 recordsLinked to original sources
PubMed1996

ePTFE coating with fibrin glue, FGF-1, and heparin: effect on retention of seeded endothelial cells.

In an attempt to improve the resistance of seeded endothelial cell (EC) to desquamation due to shear stress, we evaluated the effect of coating expanded polytetrafluoroethylene (ePTFE) grafts with fibrin glue (FG) containing fibroblast growth factor 1 (FGF1) and heparin on the retention of EC exposed to pulsatile flow ex vivo. Five pairs of ePTFE grafts (30 microm internodal distance, 4 mm internal diameter, 7 cm long) were coated with either FG/FGF-1/heparin (fibrinogen 32.1 mg/ml, thrombin 0.32 U/ml, FGF-1 11 ng/ml, heparin 250 U/ml) or fibronectin (FN) (20 microgram/ml). Canine jugular vein endothelial cells (Factor VIII, passages 5-7), were radiolabeled with indium-111 (100 microCi/1 million cells). Cell seeding (3 x 10(5) cells/cm2) was achieved by four successive inoculations of cells separated by 90 degree graft rotations. After overnight incubation (37 degrees C), pairs of FG and FN grafts (5 cm long) were simultaneously perfused ex vivo with culture media containing 10% fetal bovine serum (120/80 mm Hg, 90 cc/min, 60 pulsations/min). During the 1-hr perfusion, perfusate samples were taken at 0, 5, 15, 30, and 60 min to determine radioactivity loss. Pre- and postperfusion whole graft radioactivity data were compared to estimate cell retention and confirmed by histologic evaluation. Mean adherent radioactivity on FG-coated grafts (96 +/- 5%) was significantly higher (P = 0.0029, Student's t test) than on FN-coated grafts (85 +/- 3%). Maximum radioactivity loss in perfusate was seen after 5 min, with lower sustained loss thereafter. The improved retention of seeded EC on ePTFE grafts coated with FG containing FGF-1 and heparin compared to FN will need to be confirmed for longer durations of perfusion and using in vivo models.

Animals↗
PubMed1995

In vivo platelet deposition on polytetrafluoroethylene coated with fibrin glue containing fibroblast growth factor 1 and heparin in a canine model.

BACKGROUND: We previously reported that the coating of expanded polytetrafluoroethylene (ePTFE) with fibrin glue containing fibroblast growth factor 1 (FGF-1) and heparin accelerates endothelial coverage of grafts implanted into animals. We report here the effect of this surface modification on early platelet deposition. MATERIALS AND METHODS: Nine dogs received 7-cm ePTFE grafts, 60-microns internodal distance, 4-mm internal diameter, as bilateral aortoiliac implants, one coated (luminal cross section and abluminal surface) with fibrin glue (fibrinogen 32.1 mg/mliters, thrombin 0.32 U/mliters) containing FGF-1 (11 ng/mliters and heparin (250 U/mliters), the other uncoated. After 5, 30, or 120 minutes of circulation with blood containing autologous platelets radiolabelled with indium 111, gamma emissions were quantitated on explants and correlated to surface areas measured by computerized planimetry. RESULTS: Both global and segmental comparisons showed significantly (P < 0.05, Student's t-test) less platelet deposition on coated than on uncoated grafts after 120 minutes of circulation, but no difference at 5 and 30 minutes. CONCLUSIONS: In this model, ePTFE coating with fibrin glue containing FGF-1 and heparin shows no adverse effect on early platelet deposition.

Animals↗
PubMed1995

Selective stimulation of endothelial cell proliferation with inhibition of smooth muscle cell proliferation by fibroblast growth factor-1 plus heparin delivered from fibrin glue suspensions.

BACKGROUND: Pretreatment of expanded polytetrafluoroethylene grafts with fibrin glue (FG) containing fibroblast growth factor-1 (FGF-1) (10 ng/ml) and heparin (50 units/ml) has been shown to induce a transmural angiogenesis with proliferation of both endothelial cells (ECs) and smooth muscle cells (SMCs) in dogs. To induce EC without SMC proliferation, we studied the effects of different FGF-1:heparin ratios within FG in vitro. METHODS: First passage human umbilical vein ECs (factor VIII+) or primary canine carotid artery SMCs (alpha-actin +) were seeded onto 96-well plates coated with FG containing 10 ng/ml FGF-1 and 0, 5, 50, or 500 units/ml heparin. Control wells were coated with FG without FGF-1 or heparin. Cells were fed standard growth medium without soluble FGF-1 or heparin. Tritiated thymidine (1 microCi/well) was added after 1, 2, or 3 days, and proliferation was assayed by scintillation counting 48 hours later. RESULTS: For both ECs and SMCs, proliferation on FG containing FGF-1 but no heparin was not different from control. EC proliferation on FG containing FGF-1 was significantly increased by addition of 5, 50, or 500 units/ml heparin (+68%, +99%, and +106%, respectively; p (0.0001 for all), reflecting the synergism of FGF-1 by heparin. SMC proliferation was also significantly increased by the addition of 5 or 50 units/ml heparin (+85% and +66%, respectively; p (0.0001 for both). However, SMC proliferation with 500 units/ml heparin was significantly decreased from control (-12%; p = 0.014), reflecting heparin's SMC growth inhibitory activity. CONCLUSIONS: FG containing 10 ng/ml FGF-1 and 500 units/ml heparin stimulates EC proliferation while inhibiting SMC proliferation in vitro. Application of this modified FG to vascular grafts or to arteries after direct or transcutaneous interventions may promote endothelialization without intimal hyperplasia.

Cell Division↗
PubMed1993

Expanded polytetrafluoroethylene arterial prostheses in humans: histopathological study of 298 surgically excised grafts.

The expanded polytetrafluoroethylene vascular prosthesis is considered to be the best synthetic alternative for peripheral arterial reconstruction. Most studies on the healing characteristics of expanded polytetrafluoroethylene prostheses have been carried out on animals, and very few data are available on prosthesis implanted in humans long term. We implanted 298 expanded polytetrafluoroethylene grafts as arterial substitutes in humans. The mean duration of implantation was 523 d and the grafts were implanted mainly for infrainguinal or axillofemoral bypass. The cellular and collagen infiltration of the microporous expanded polytetrafluoroethylene structure was generally poor. Infiltration occurred mainly in the external region of the prosthetic wall and increased with the duration of implantation. The external reinforcement was not a major factor in limiting tissue infiltration. The luminal surfaces were covered with a thin, irregular layer of organized fibrin, interspersed with exposed expanded polytetrafluoroethylene areas. Mineral deposits were observed in five cases. Despite poor healing, the clinical performance of expanded polytetrafluoroethylene vascular prostheses is relatively good. Since the chief advantage of this material is good mechanical stability in vivo, any modifications of the graft to improve healing characteristics or thrombogenic properties should not be made at the expense of stability in vivo.

Adult↗
PubMed1993

Expanded polytetrafluoroethylene arterial prostheses in humans: chemical analysis of 79 explanted specimens.

The expanded polytetrafluoroethylene (ePTFE) vascular prostheses are widely used as small and medium diameter blood conduits when an autologous venous material is not available or is not suitable. The long-term performance of a prosthesis is dependent on several factors, including its healing characteristics and its stability in vivo. This study was undertaken to assess whether chemical degradation of ePTFE occurs when such arterial substitutes are implanted in humans. Seventy-nine ePTFE grafts excised for complications were analysed using the following techniques: measurement of the contact angle (theta), electron spectroscopy for chemical analysis (ESCA or XPS), Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC). The results were compared with those obtained from virgin ePTFE and virgin ePTFE washed prostheses. The measurement of the contact angle (theta) permits the comparison of the level of hydrophobicity of material after in vivo residency. The contact angles of explanted ePTFE grafts are greater than those of virgin ones but remain close to those of washed virgin prostheses. The ESCA method allowed investigation of the chemical changes which occur on the surface of ePTFE prostheses after implantation because of the low penetration of the X-ray (about 50 A). This study did not reveal any chemical degradation of the ePTFE with time of implantation for periods up to 6.5 yr. Changes in the surface composition were probably related to lipid and/or protein uptake. The FTIR spectroscopy provides information about the chemical composition of material. Compared with the virgin ePTFE prostheses, the FTIR spectra of explanted prostheses showed specific bands which are characteristic of lipid and/or protein absorptions. The bulk properties of ePTFE studied by DSC did not show any significant changes with time of implantation. It is concluded that ePTFE grafts remain stable in vivo for periods up to 6.5 yr.

Biocompatible Materials↗
PubMed1991

A pathological study of arterial prostheses surgically excised after overt clinical infection.

Infection caused regarding vascular grafts in vascular surgery still remains a major problem. To reduce this problem and the complications which follow, the surgeon must be able to apply the best surgical management and also be confident with the vascular substitute used. There are two important factors to be considered: the biomaterial must have low propensity to infection and good stability if and when infected. In an attempt to verify this problem, 93 vascular grafts surgically excised for overt infection were examined. Techniques used for examinations were gross morphology, histopathology and scanning electron microscopy (SEM) evaluation. There were 23 human umbilical vein (HUV) grafts, 51 Dacron grafts and 19 expanded polytetrafluoroethylene (ePTFE) grafts. Histopathological signs of infection were absent in 57% of the ePTFE and Dacron grafts and in 17.4% of the HUV grafts. The latter were more heavily histologically infected and in some cases the walls were destructed. Histopathological signs of infection were seen on all the prosthetic walls in 36% of all the specimens and were mainly on the external portion of the grafts for the remaining prostheses. Bacteria were seen in respectively 21.7, 15.7 and 20% of the HUV, Dacron and ePTFE grafts with the Gram stain and in 86.9, 84.3 and 94.7% with SEM. The implantation period was shorter for the bioprostheses compared to that of the synthetic grafts because of the site and the indication of implantation. The stability of the bioprostheses was lower compared to that of the synthetic grafts when infected, leading to a breakdown of the wall along the length of the graft. The infection was found on the external capsule of the grafts rather than on the luminal surface.

Arteries↗
PubMed1991

[Ruptured abdominal aortic aneurysm: long-term survival].

Despite technological improvement, surgery for ruptured aortic abdominal aneurysm (AAA) only gets about 50% of patients to survive past the operative period. This series addresses the long-term outcome of those survivors. Eighty consecutive patients operated on for ruptured AAA between January 1983 and June 1990 at l'hôpital du Saint-Sacrement by three vascular surgeons, were studied and compared to 279 patients submitted to elective aneurysm surgery during the same period. The operative mortalities were respectively of 45% (ruptured) and 6.1% (elective). Five year survivals added up to 30 and 68%. When the 5 year survivals were recalculated, including only patients who were discharged from hospital, we found no statistically significant difference (p greater than 0.05) between the ruptured (55%) and the elective groups (68%). Data from this series demonstrate that long-term survival of patients undergoing ruptured AAA surgery is good and compares with that of AAA elective surgery. Therefore, aggressive treatment of ruptured AAA remains justified.

Actuarial Analysis↗
PubMed1989

Comparative plasma levels of doxepin and desipramine in the elderly.

Although tricyclic antidepressants remain a principal mode of treatment of depression in the elderly, concomitant medical illness in this subgroup creates particular concern regarding the safety of these drugs. Doxepin has gained favour for use in the geriatric population due to claims of low cardiovascular side effects. This perceived safety has been questioned, however, since few investigators have actually reviewed plasma levels. A recent finding of interest revealed that two patients on 150 mg of doxepin daily with assured compliance had undetectable levels of doxepin or desmethyldoxepin in their plasma. A prospective study was consequently undertaken to compare oral doses and plasma levels of doxepin with desipramine as a standard reference compound. Data was collected for 19 females (12 on doxepin, seven on desipramine) and 12 males (five on doxepin, seven on desipramine) with a mean age of 76. Eight patients on doxepin showed undetectable plasma levels as compared with none on desipramine. This is a highly significant difference. Although the therapeutic plasma range for doxepin remains controversial, it is unlikely that patients can respond to levels of zero. The authors recommend routine monitoring of doxepin levels in the elderly and question poor bioavailability or absorption of this tricyclic antidepressant in some patients.

Administration, Oral↗
PubMed1987

Albumin-coated polyester arterial prostheses: is xenogenic albumin safe?

This paper adds a new dimension to the series of studies concerned with the development of an albumin-coated polyester vascular prosthesis by addressing the question of the origin of the albumin. Previous experiments in dogs have used canine albumin-coated polyester arterial grafts. This study evaluated the biocompatibility of xenogenic material by implanting in dogs prostheses coated with bovine albumin and cross-linked with glutaraldehyde. Two series of albuminated grafts, one gamma radiation sterilized, the other ethylene oxide sterilized, as well as a preclotted control series were undertaken. The origin of the albumin did not appear to be significant. In fact, the healing pattern of the xenogenic albumin coated grafts was identical to that found previously with isogenic albumin. Nor did the method of sterilization produce significantly different pathological results. However, a slower rate of healing with the coated grafts compared to the preclotted controls did appear to be related to the slow rate of albumin erosion and the potentially cytotoxic effect of the glutaraldehyde cross-linking agent.

Albumins↗
PubMed1987

[Fibrous hyperplasia in femoro-popliteal bypasses using treated human umbilical veins].

The authors report two clinical cases of the failure due to fibrous hyperplasia of processed human umbilical vein (HUV) grafts employed as femoro-popliteal bypasses. Failure occurred after 19 months implantation at the proximal anastomosis for one graft and after 10 months at the distal anastomosis for the other. Fibrous hyperplasia was the principal cause of reoperation. The lightly vascularized, more or less compacted fibrin involved, adhering loosely to the HUV, remains thrombogenic at the blood-contacting surface. Superposed onto this phenomenon which is widespread in laboratory animals but uncommon in humans, are the usual causes of failure: delamination of the HUV wall, lipid uptake and bacterial colonization.

Blood Vessel Prosthesis↗
PubMed1986

The initial blood retention properties of arterial prostheses.

The initial contact between blood and vascular grafts may be a determinant of the fate of the implants. They behave in different ways depending upon their nature: the processed human umbilical vein and the bovine heterograft just lead to minimal thrombotic retention; the expanded PTFE is even more antithrombogenic; the porous polyesters which are porous textiles, should be totally impregnated with a thrombotic matrix to make the wall impervious. These observations were clearly determined by exposing the grafts to blood, incorporating either labeled platelets or labeled fibrinogen, and they were correlated by SEM examination.

Arteries↗
PubMed1986

Anastomotic false aneurysms with aortic Dacron graft after twenty-five years.

One of the early diamond crimped knitted polyester (Dacron) grafts was surgically excised after implantation for 25 years in the aorto-biiliac position because of false aneurysm formation at the three anastomotic sites. The sutures were no longer visible. While the areas around the false aneurysm were poorly incorporated, the graft limbs were well encapsulated with some endothelial-like cells on the luminal surface. The integrity of the graft was well preserved despite mild fraying and the disruption of one stitch.

Adult↗
PubMed1986

Chemically fixed human umbilical cord vein grafts as arterial substitutes: potential and limits.

In spite of reported successes, synthetic fabric grafts and microporous and plain synthetic conduits have proven unsuitable for aorto-coronary bypasses and showed weaknesses below the knee. Readily available and uniform diameter vascular substitutes with biological and mechanical properties comparable to human vessels would be of paramount interest. Following reported successes with chemically fixed human umbilical veins (HUV), we have attempted to develop smaller diameter blood conduits and have improved the currently prevalent techniques of fixation, preparation and storage to generate more convenient surgical products. In vitro assessment of the processed HUV demonstrated that the HUV can be easily processed to make an arterial substitute that can be preserved either in a liquid medium or as a dry product. However, the in vivo implantations in dogs led to disappointing results for liquid-preserved or albuminated veins. Critical-point dried grafts gave better results, unfortunately they do not heal and they can only degrade after implantation.

Animals↗
PubMed1986

[Analysis of arterial microporous teflon prosthesis following surgical excision].

Twenty-one prosthetic explants were analysed after being surgically excised from 19 patients whose average age at implantation was 54.8 years. The arterial prosthesis was implanted 19 times for an advanced arteriopathy (stage III and stage IV) and twice for a stage II. The average time that the implants were in place was 14.8 months (with extremes of 19 days and 4 years). Surgical reintervention was caused by thrombosis (18 cases), infection (twice) and one case of degeneration of the prosthesis. The explanted prostheses displayed an irregular capsule, an uneven filling of the wall and a fibrous proliferation adhering to the internal surface. The role of the latter appeared essential to the prevention of the invasion of the prosthesis wall by fibrous tissues. The destruction of the structure of the microporous teflon is also prevented. Furthermore, this prosthesis seemed adversely affected when creased by flexion: the reduction in the caliber of the internal lumen caused thrombosis and a detachment of the external capsule. When such a material is implanted, everything must be done to prevent twisting or damaging the prostheses.

Aged↗
PubMed1986

The virgin, modified, human, umbilical vein graft: morphologic characteristics and mechanical properties.

The authors used macrophotography, endoscopy, roentgenography, light microscopy, and transmission and scanning electron microscopy to assess the morphologic characteristics of 37 virgin, human, umbilical vein grafts. The specimens showed deep longitudinal folds (22%) and multiple transverse folds of the intimal surface (27%), irregularity of wall thickness (41%) and intimal breakdown exposing thrombogenic layers of the vein wall to blood (19%). The mechanical properties also studied were dynamic compliance, Young's modulus, breaking strength and breaking strain. The mean dynamic compliance was 6.44 X 10(-4) mm Hg-1 (SD = 2.02 X 10(-4) mm Hg-1, i.e., 31%), which is in agreement with results of others. The specimens showed great variability in Young's modulus, breaking strength and breaking strain. The structural deficiencies and variable mechanical properties of human umbilical vein grafts require investigation to determine their effect on patency rates due to increased thrombogenicity and thus to establish whether there are potential hazards associated with their use.

Biomechanical Phenomena↗
PubMed1985

A compound arterial prosthesis: the importance of the sterilization procedure on the healing and stability of albuminated polyester grafts.

In response to the demand for a vascular prosthesis which achieves reliable haemostasis without preclotting, a new compound albumin/polyester prosthesis has been developed. In order to optimize the sterilization procedures for this device, two series of implantations in the thoracic aorta of dogs were undertaken to compare the effects of ethylene oxide (EtO) and gamma-radiation. Preclotted polyester prostheses were implanted in two additional control series. Pathological analysis of the explanted grafts indicated that gamma-radiation is to be preferred over EtO because it results in faster rates of healing. While the albumin coating delayed the thrombotic response and fibrinolytic activity, the extent of healing of the radiation sterilized graft was equivalent to that achieved by preclotted polyester prostheses in the medium and long term. Measurements of the strength and dimensional changes of the graft demonstrated that, in addition to reducing the risks of acute thrombosis and postoperative haemorrhage, the albumin coating improves the dimensional stability of the knitted structure.

Albumins↗
PubMed1985

[Physical characteristics of stripping veins preserved at 4 degrees C and usable as artery substitutes].

The mechanical behavior of varicosis veins harvested during stripping and preserved at 4 degrees C has been investigated by measuring the compliance, the yield strain, the yield stress and the longitudinal Young's modulus. No relationship has been demonstrated between those parameters and external factors such as age, sex, storage duration and bacteremic contamination. The mechanical behavior of such veins is unpredictable. Therefore, it is mandatory to proceed through individual and non-destructive quality control tests to obtain a selection of grafts suitable for implantation. Moreover, implantation should be oriented towards patients who are able to visit the hospital frequently since the healing capacity of the venous homograft is unpredictable.

Arteries↗