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Biomedical subjects

M Marois

Publications and source records attributed to M Marois.

At least 73 records · Page 4Linked to original sources
PubMed1980

Processes human umbilical veins as arterial substitutes--evaluation in canine models.

Human umbilical cord vein segments have been used as vessel substitutes for damaged or occluded arteries, as aorto-coronary by-passes and as arterio-venous fistulae for dialysis. The Dardik-Biograft fixed with glutaraldehyde and the Mindich-Bioflow, fixed with ethanol and dialdehyde starch, are commercially available. They were implanted in dogs as replacements for a segment of the abdominal aorta. Post-implantation status was followed by angiography. They were evaluated after removal from sacrificed animals with the aid of scanning electron microscopy and histological techniques. Attention was focused on vessel patency, dimensional stability, integrity of the anastomosis line, lumen wall microstructure, evidence of suture damage and thrombus deposition pattern. Both types of grafts gave functional by-passes for at least until 6 months post-implantation. The Dardik-Biograft appeared more prone to thrombus formation near the anastomosis. Sparse cellular development was also noted. The Mindich-Bioflow gave rise to a prosthesis of superior thromboresistance which was more subject to mechanical damage.

Animals↗
PubMed1980

Another look at the Sparks-Mandril arterial graft precursor for vascular repair. - Pathology by scanning electron microscopy.

The Sparks-Mandril blood vessel precursor system, an autogenous tissue growth-promoting device, in spite of its ingenuity and its surgical elegance, has received only limited usage. At technique for peripheral blood vessels by several authors. In the latter period, this laboratory also undertook similar work. The results of seven implantations in dogs and two in patients are reported here in the context of a program on the evaluation of blood vessel substitutes, their mode of operation and their long term performance. The clinical status and the pathology of the grafts at time of failure were investigated using techniques of scanning electron microscopy. This work confirms the findings of other centres regarding the generally unsatisfactory performance of the Sparks-Mandril system. Possible causes for failure in mandril-formed blood vessels are discussed.

Adult↗
PubMed1980

[Polyethylene terephtalate (Dacron) prostheses as arterial substitutes. Value of commercial grafts as abdominal aorta substitutes in the dog (author's transl)].

Most of the presently available Dacron fabric grafts are either woven or knitted; some are velours. Whereas the various configurations and textures can be easily recognized and classified with respect to morphology, structure, porosity and fabric tenacity, it is also necessary to establish their post-implantation healing characteristics. Canine models have been used to investigate the healing characteristics of 18 types of prostheses over implantation periods from one to six months using techniques of scanning electron microscopy and conventional light microscopy. Velours exhibit superiar tissue ingrowth but the internal tissue lining does seldom embeds all of the fibres. Complete neoendothelialization is not achieved; the process appears more closely linked to haemodynamic factors such as shear forces acting postfacto on blood deposits as opposed to graft porosity facilitating ingrowth. More meaningful criteria of performance must be found to allow a closer matching between the available products and the individual clinical needs of each situation.

Animals↗
PubMed1980

Cardiovascular sutures as assessed by scanning electron microscopy.

Nine types of commercial sutures were investigated with respect to their suitability in cardiovascular surgery involving anastomosis of arterial prostheses. Polyester, nylon, silk and polypropylene in the form of multifilaments and monofilaments with or without coatings were included. The gross structure of the suture and the needle, the uniformity of the fibres and the coatings, the mechanical properties, before and after surgical use and the quality of the resulting anastomoses in canine models were evaluated. Although all surveyed products were potentially usable for the purpose intended, some appeared more suitable. Intraoperative damage to the sutures was found to be extensive and may play an important part in the long-term security of the anastomoses.

Cardiac Surgical Procedures↗
PubMed1980

A SEM investigation of the trauma to prostheses and arteries during vascular reconstruction procedures.

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 materials inflict damage to the adjacent tissues as well as the prosthesis. This effects the thrombotic behavior and healing pattern of the area. The prognoses for long term success are, as a consequence, directly influenced. Various vessel occluding devices were evaluated on 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 the most satisfactory. The development of less traumatic surgical devices and possible modifications in the surgical protocols are discussed with the aim of further reducing surgical trauma.

Animals↗
PubMed1980

[Evaluation of two commercial bovine vascular heterografts (author's transl)].

Two commercially available grafts made from chemically modified bovine carotif arteries, Artegraft (Surgikos Corp. U.S.A.) and Solcograft (Solco A.G. Switzerland), were evaluated. Preliminary evaluation indicates that these products compare favorably with other more common chemically treated grafts of biological origin. Morphological characteristics, inflammatory response and thrombogenic potential were measured. Their structure suggest that each of the processes conserve the collagen morphology of the media and the adventitia originally present in the precursor arteries. Test implantations in dogs reveal a tendency to undergo stenosis near the anastomoses within a few months. After six months of in-vivo function, these grafts are not invaded with the expected neo-formed cells and new collagen in their central portion; this process takes place only near the anastomoses.

Animals↗
PubMed1979

[Comparison of the action of an impeded estrogen, frideron, and of estradiol on the seminal vesicles and on the weight of the testicles and accessory sex glands in the rat. II].

We have undertaken a comparative study on the effects of estradiol and of an impeded estrogen, zeranol, in the prepubescent Wistar male rat. Both had an inhibitory effect on the secretion of F.S.H. in the spermatogenesis test. Nine injections of estradiol or nine ingestions of zeranol had a restraining effect with a dose of 0.5 microgram of estradiol or of 500 micrograms of zeranol (for 100 g of body weight). With some animals, spermatogenesis is interrupted and the weight of the testicles decreased; the treatment is more active with stronger doses: 2 micrograms of estradiol interrupted spermatogenesis in 10 rats out of 11, 1.000 microgram of zeranol interrupted it in 10 rats out of 13. A weak dose of either estrogen (0.05 microgram of estradiol or 20 micrograms of zeranol) stimulated the growth of the seminal vesicles, the prostate gland and the preputial glands. Strong doses decrease the weight of the preputial glands, and even more the weight of the prostate gland (10 micrograms of estradiol, 1.000 microgram of zeranol). They are ineffective on the seminal vesicles. The effects of 2 micrograms of estradiol on the testicles and the accessory sexual glands are completely inhibited by the simultaneous administration of 2 U.I. of P.M.S. rich in FSH.

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↗
PubMed1978

[Morphological variations of rat mammary glands according to the age and the environmental factors (author's transl)].

We took the microscopic study of the mammary gland lactation as a test of prolactin (Prl) secretion in female rats. Aging is liable to cause the acini secretion in 7 females out of 17. Constant light or the repetition of stresses which are known to increase the serum Prl concentration have no effect in young females' mammary gland but always cause an abundant lactation in the 18 old females. In this test, aging and environment can be synergistic.

Aging↗
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↗
PubMed1977

[Action of an antiestrogen agent, tamoxifen on the uterus and vagina of the ovariectomized rat].

Tamoxifen has more or less strong estrogen influence according to the targets : a light one on the uterus (1 mg being much less strong than 0.25 microgram of estradiol), a dynamic one on the vagina (50 microgram of tamoxifen make the vagina open in as short a time as 0.25 microgram of estradiol do but the keratinisation is still not completed even with 1 mg of tamoxifen). We can still see this influence four days after the end of the treatment. This influence is weak on the uterus until the 11 th day and it is much stronger on the vagina until about the 8 th day. Tamoxifen has an antiestrogenic action when opposed to 20 microgram of estradiol : this action is limited as soon as you give a dosis of 50 microgram on the uterus and it is nearly total with a dose of 1 mg ; we can notice it on the vaginal only from 200 microgram on.

Animals↗
PubMed1977

[Action of an antiestrogen agent, tamoxifen on the mammae of ovariectomized rats].

We have been studying the estrogen and antiestrogen action of tamoxifen and of clomifen on the development and secretion of acini and of the galactophore canals of the mammary gland. The ICI (50 or 200 microgram) has no effect : the very strong dose of 1 mg gives a light stimulation of the acini secretion which can be compared to that of light doses of clomifen (20 or 50 microgram) or of estradiol (0.25 microgram). Only 10 microgram of estradiol alone allow the development, the opening and secretion of acini. With 20 microgram, this action is more apparent, not only on the often dilated acini, but also on the canals. Administered along with 20 microgram of estradiol, tamoxifen is slightly antagonist with 50 microgram, strongly antagonist with 200 microgram, and completely antagonist with 1 mg. 50 microgram of clomifen are inefficient ; it is synergetic if the treatment starts and is over 4 days before the estradiol treatment.

Animals↗