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Biomedical subjects

C Gosselin

Publications and source records attributed to C Gosselin.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1985

[Stripped veins for secondary vascular access in hemodialysis. Pathologic study of the grafts after surgical excision].

The suitability of stripping vein homografts as AV fistulae for intermittent hemodialysis has been evaluated. Microscopic investigation of stored veins indicated the superiority of cryopreservation over refrigeration. A systematic study of 12 venous homograft fistulae surgically excised from hemodialysis patients revealed that the homograft walls are the sites of both connective tissue proliferation and of mural degeneration. It was also noted that the implants failed in the short term (less than 1 yr) mainly due to stenosis, in the medium term (1 yr-3 yrs) mainly due to aneurysmal dilatation and for a variety of reasons beyond 3 years. It was concluded that when suitably selected, handled and stored, stripping vein homografts are a viable alternative to treated human umbilical or bovine heterografts as blood access fistulae if no autograft is available.

Arteriovenous Shunt, Surgical↗
PubMed1984

[Mechanical fatigue of an arterial prosthesis].

This case study reports the analysis of a knitted polyester arterial prosthesis that was implanted in an 18-year old patient for five years following a bicycle accident which injured the left external iliac artery. In spite of the prosthesis, the patient continued to participate in competitive cycling. The graft became dilated and stretched by tension from the hypertrophic psoas muscle, and because the patient presented with pain and claudication, a second surgical operation was performed. The central region of the prosthesis was badly kinked. A segment was resected and analyzed in terms of pathological, textile and chemical properties. The analysis showed a poorly healed graft that had suffered from mechanical and chemical degradation. The findings point to the wisdom of implanting woven rather than knitted grafts in young patients and also suggest that in this particular case, where mechanical deterioration was accompanied by chemical degradation, it would have been preferable to remove the whole prosthesis.

Adolescent↗
PubMed1984

Cytocompatibility of albuminated polyester fabrics.

An alternative to the usual technique of preclotting porous textile vascular prostheses prior to surgical implantation is to render them impermeable to blood by impregnation with a cross-linked albumin filler matrix. This material subsequently becomes the foundation for cellular development. The compatibility of such impregnated fabrics with newly formed endothelial cells has been evaluated by an in vitro organotypic culture method. This technique enables the characterization and numeration of cells that develop on blood contact surfaces and enables determination of their rate of development. Woven, knitted, and velour fabrics were evaluated following coating with albumin and either storage in Tyrode solution or 40% ethanol or desiccation by critical point drying. Preclotted cardiovascular repair fabrics prepared according to conventional surgical protocol served as controls. The identification of the newly formed cells was confirmed histologically. The most extensive and rapid cellular development was observed on the woven fabric and is believed may have resulted from the smoother surface topography of this substrate. Good cellular development was noted particularly on fabrics which had been stored in Tyrode solution. Ethanol had a deleterious effect on the apparent compatibility.

Albumins↗
PubMed1984

Albumin coating of a knitted polyester arterial prosthesis: an alternative to preclotting.

Coating a knitted polyester arterial prosthesis with cross-linked albumin fills the interstices of the graft and relieves the surgeon of the necessity to preclot . This is of particular value in patients whose blood clotting properties are hypercoagulable, or hypocoagulable . In addition, such prostheses require less handling, which can lower the risk of bacteremic colonization and shorten the operative time. The in vivo behavior of the implanted albuminated prosthesis in the thoracic aorta of dogs is similar to that of preclotted grafts, although the sequences of early healing are different. The preclotted graft develops a continuous, thick thrombotic matrix on its luminal surface during the first 4 hours of implantation. Following the initiation of the fibrinolytic mechanism 24 to 48 hours postoperatively, this thrombotic deposit quickly recedes , leaving blood cells and platelets adhering here and there to the prosthetic surface. In comparison, the albuminated coating is not associated with major early thrombotic deposits. The albumin remains visible between the filaments during the first 2 weeks of implantation. Both treated and control grafts contain numerous thrombi on their inner surface after 1 to 2 weeks. After 1, 3, and 6 months, both implants are well encapsulated and present a glistening and continuous luminal surface. This excellent healing, however, can be compromised should the graft adhere too closely to the animal's lungs.+2

Albumins↗
PubMed1984

[The Sparks-Mandril arterial prosthesis. An ingenious concept, a total failure. What can we learn from it?].

In spite of its ingenuity, the Sparks-mandril concept has failed to generate a satisfactory arterial substitute. Pathological analysis of prostheses retrieved from humans and explanted from dogs as part of a controlled laboratory study has demonstrated that the tissue laid down during the autogenous generation stage contains neither elastin fibers nor smooth muscle cells capable of providing the required dimensional stability of a blood vessel. The supporting polyester mesh tube has been found to stretch in vivo, resulting in dilation and lengthening of the prosthesis and the formation of aneurysm and thrombosis. It is recommended that the use of devices relying on the Sparks-mandril concept not to be reintroduced until such time as the mechanism of growth promoting factors for angiogenesis are fully understood.

Adult↗
PubMed1984

[Progressive complications associated with the use of a bovine heterograft for vascular access].

Three bovine carotid heterografts, used for vascular access, were analysed after removal following the development of aneurysms in two cases and thrombosis in one. The first prosthesis was implanted in a 17-year-old man who suffered from myasthenia gravis and was undergoing plasmapheresis. It became notably dilated several months after implantation, and resection was necessary 14 months after insertion. The second graft was placed in a 31-year-old woman being treated for a severe chronic potassium insufficiency. It was removed 16 months after insertion because of thrombosis. The third bovine carotid heterograft was inserted in a 48-year-old patient on long-term hemodialysis and was removed 3.5 months later because of aneurysmal dilatation adjacent to the arterial anastomosis. These evolutionary and degenerative changes associated with the bovine carotid heterograft illustrate the limitations of this material as an interpositional limb for arteriovenous fistulas in angioaccess therapy. Small weaknesses have sometimes been noted in the microstructure of the graft material studied before implantation.

Adolescent↗
PubMed1984

[First contact between blood and the arterial prosthesis. Study of the retention of the blood elements].

In order to characterize the nature of the interaction between arterial prostheses and their initial contact with blood, we propose the use of an in vitro test using labelled platelets and fibrinogen to measure the amount of the thrombotic matrix that is entrapped by the wall of the graft. The results have been confirmed by scanning electron microscopy. Polyester prostheses, whose healing process depends on the reorganisation of the thrombotic matrix, retains considerably more blood cells than the polytetrafluoroethylene microporous prostheses or the treated biological devices, whose fate, following implantation, maintains almost complete passivity.

Biocompatible Materials↗