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Biomedical subjects

D Domurado

Publications and source records attributed to D Domurado.

At least 37 records · Page 2Linked to original sources
PubMed1986

Degradability of crosslinked albumin as an arterial polyester prosthesis coating in in vitro and in vivo rat studies.

In order to avoid the preclotting procedure in knitted polyester arterial prostheses and in woven models, compound polyester grafts have been proposed, containing preadsorbed collagen or albumin. Since we are currently investigating grafts impregnated with crosslinked albumin, it was decided to establish the degradation rate of this coating after stabilization with either glutaraldehyde (GA) or carbodiimide (CDI). Tests were performed in vitro by incubation in either PBS, plasma or pancreatin and in vivo by implantation in the abdominal cavity of rats. In PBS or plasma in vitro, the coatings were very stable (2% degradation after 144 h incubation), however, in pancreatin the CDI crosslinked albumin degraded much faster than the GA crosslinked albumin (more than 50% degradation in 12 h compared to less than 30% in 48 h). In vivo the degradation rates of the two types of crosslinked albumin were similar (almost all of the albumin having been lost after 4 weeks) but the cellular response was very different: a mild tissue reaction was observed with the CDI crosslinked coating whereas many foreign body giant cells were present on the GA crosslinked material.

Albumins↗
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↗
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↗
PubMed1983

Polyester prostheses as substitutes in the thoracic aorta of dogs. I. Evaluation of commercial prostheses.

Using canine models, a representative selection of polyester or Dacron vascular prostheses, including woven, knitted, and velour types, were evaluated for their relative healing characteristics and for their structural changes during implantation. Following residence periods ranging from 4 h to 6 months at the site of the thoracic aorta, the dogs were sacraficed, and the grafts were excized for measurement of the thrombogenicity of the flow surface and for pathological examination by light microscopy and SEM. The kidneys were also removed and examined for infarcts caused by any trapped circulating emboli. The extent of healing, the presence of embolizing nuclei, and the thrombogenicity and morphology of the lumen surface were also assessed. The healing characteristics of each type of device proved similar. Velour fabrics exhibited more extensive encapsulation, but frequently their internal capsules failed to incorporate all the fibers. In all cases, cellular development on the lumen was limited to areas contiguous to the anastomoses. The initial porosity of the devices as measured by water permeability did not appear to influence the healing sequence to a significant extent. The grafts did exhibit differences in structural stability depending on whether they were of a knitted or woven construction. We suggest that users consider these different mechanical and structural properties when making their choice of a graft. Despite these differences, we believe that the healing process is far more host dependent than graft dependent.

Angiography↗
PubMed1981

Effects of traumatic manipulations on grafts, sutures, and host arteries during vascular surgery procedures. Experiments on dogs.

Scanning electron microscopy was used to diagnose incidents of trauma and the pattern of healing following surgical implantation of microporous blood vessel substitutes. Vascular reconstruction procedures using autogenous or synthetic prosthetic material inflict damage to the adjacent tissues as well as the prosthesis. This affects the thrombotic behavior and healing pattern of the area. The prognosis for long-term success are, as a consequence, directly influenced. Various vessel-occluding devices were evaluated in canine models with respect to their ability to damage blood vessels at the clamped site. The impact of suture needles on tissues and prosthetic materials was also considered. Of the various vessel-clamping devices which are commercially available, those which have elastomeric shields on the clamping components were found to be most satisfactory. The development of less traumatic surgical devices is discussed with the aim of further reducing surgical trauma.

Animals↗
PubMed1981

[Liquid storage media for vascular prosthesis of biological origins : their impact on biocompatibility (author's transl)].

Unlike synthetic arterial substitutes which are supplied as presterilized, dry-packaged products with potentially indefinite shelf lives, arterial prosthesis of modified biological origin must stored in less convenient liquid preservative media. These preservatives can affect the post-implantation performance and the biocompatibility of the devices. In order to identify the most suitable media, a modified "in vitro" cell culture test method was developed. It makes use of endothelial cells prepared from the aorta of chick embryo. In general, the prosthesis stored in liquid media had a disappointing performance from the point of view of neo-endothelium development and adhesion. Residual cytotoxicity was also noted for most of these currently used prosthesis storage and pre-surgical preparation protocols. Although devices stored in physiologic media showed adequate biocompatibility according to this cell culture test, it appears that neo endothelialization does not proceed concurrently with healing. Cellular development where present, adheres poorly to the substrate and cannot resist the shear forces of normal blood flow. Pre-implantation treatment of such prosthesis with cellular growth-promoting substances may enhance cell-prosthesis adhesion.

Animals↗
PubMed1978

Scanning electron microscope study on flat type membrane oxygenator after prolonged extracorporeal circulation.

Despite adequate anticoagulation, thrombi may develop onto any foreign surface subjected to circulating blood. Although the efficiency of membrane oxygenators can decrease, distal embolization can be more critical and dangerous. Scanning electron microscope observations carried out on the Travenol Modulung oxygenator used both on dogs and on patients for prolonged partial cardiopulmonary by-pass pointed out the following observations. Caution must be observed when translating the results from dogs to human beings. Heparin management can be delicate and critical. The problem of blood transfusion can be extremely important and must be extensively investigated.

Adult↗
PubMed1978

Thrombus formation in a staged capillary membrane oxygenator associated with a microaggregate blood filter: a scanning electron microscope study.

Blood contact at interfaces in extracorporeal devices is a source of traumas. Proteins are very rapidly adsorbed; then, depending on which proteins are left various degrees of platelet aggregation follow and thrombi develop. The scanning electron microscope reveals very instructive information on the morphology of the blood deposits which adhere to foreign surfaces. Oxygenators such as the Awad D, which is a staged one made of silicone rubber, become "thrombus invaded" after prolonged extracorporeal circulation in spite of adequate heparinization of the blood. In most cases, evaluation of membranes and devices is assessed with respect to transfer of blood gases. Careful examination of the morphology of deposits should be developed. This study shows the importance of blood flow rate, design, and materials.

Animals↗
PubMed1978

Endothelial lesions associated with vascular clamping--surface micropathology by scanning electron microscopy.

The endothelial cell pavement in normal blood vessels is very fragile. In cardiovascular surgery, the need for secure clamping of the aorta results in trauma which may be followed by thrombosis or occlusion. Various types of vascular clamps and other related devices offered commercially were clinically investigated in canine models and their effects on the vascular endothelium were ascertained with the aid of scanning electron microscopy. On the basis of these studies, the Fogarty silicone filled clamp appeared to be the least traumatic. However, further technical developments in this area are needed in order to obtain a completely atraumatic method of temporarily closing major blood vessels.

Animals↗
PubMed1978

Albuminated dacron protheses as improved blood vessel substitutes.

An improved vascular graft was achieved by treating knitted Dacron prostheses with cross-linked albumin. Eight segments, each six centimeters in length, were coated and implanted in the canine thoracic aorta for periods ranging from 24 hours to six months. The results were compared with the eight untreated grafts implanted for similar periods as control experiments. Albumin coating resulted in a faster healing : cells appeared earlier and collagen development was greater. The most beneficial effect of that treatment was the reduction in embolization, as shown by the considerable decrease in kidney damage.

Animals↗
PubMed1977

Stored blood microfiltration. Evaluation of micro-aggregate filter composed of polyurethane foam and nylon wool.

Aggregates of amorphous material which develop during storage of banked blood have been implicated as a cause of pulmonary micro-embolism in man following massive transfusion. Such pulmonary micro-embolism may be a causal factor in the development of post traumatic pulmonary insufficiency. At present several microaggregate filters for use in massive transfusion are commercially available, and on of these is the Fenwal filter. It is composed of a screen filter which removes microclots of 250 microns and higher, a layer of polyurethane foam and a layer of nylon wool. The resistance of this device is very acceptable and the filter may be used for several blood units, but its efficiency seems less than that of Dacron wool filter.

Blood Platelets↗
PubMed1977

Dacron as arterial prosthetic material: nature, properties, brands, fate and perspectives.

Dacron graft prostheses are routinely implanted to overcome impairment of arterial flow to distal tissues. Many different fabric configurations have been developped and evaluated. Unfortunately, after implantation the flow surface of any graft persists as a fibrinous lining. No human specimen has a commonly ingrown extension of tissue exceeding some millimeters in length. Full wall healing and endothelialization of arterial prosthesis is a goal that must be pursued intensively because it seems that the goal is attainable.

Animals↗
PubMed1976

Thrombus formation and microaggregate removal during prolonged extracorporeal circulation using a capillary membrane oxygenator. A scanning electron microscope study.

Despite adequate heparinization, thrombus formation occurs at the blood/foreign material interface. Depending on the part of the device, the material and the blood flow, the amount and the components of thrombi vary greatly. This is not dangerous by itself but clots can be expelled downstream and damage the lungs, brain, kidney and retina. Interposition of a filter may prevent risks of embolization. The present paper reports the scanning electron microscope study carried out on the Awad oxygenator after use during prolonged extracorporeal circulation on 13 dogs. No filter has been inserted in the circuit for the first six experiments. A screen filter (4) or a polyurethane foam filter (3) was employed in the following ones.

Animals↗
PubMed1976

Intra-uterine devices, A SEM study on the Dalkon Shield.

A SEM study carried on intra-uterine devices (Dalkon Shield) is reported. The poor manufacturing of the devices is stressed, which could increase their efficiency but also the risks of penetration, or worse, perforation. The solution for the future could be copper bearing intra-uterine devices coated by hydrogels. This should maintain efficiency and improve security.

Female↗
PubMed1976

Blood compatibility of silicone rubber chemically coated with cross-linked albumin.

A new method is reported for chemically coating cross-linked albumin onto silicone rubber in an attempt to improve the blood compatibility of the material. Promising results were obtained in an evaluation using both vena cava and renal embolus antithrombogenicity tests ondogs. Coated silicone rubber rings induced much less renal emboli than uncoated ones after one week implantation.

Albumins↗