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Biomedical subjects

L Martin

Publications and source records attributed to L Martin.

At least 523 records · Page 29Linked 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

Intussusception complicated by distal perforation of the colon.

Three cases of perforation of the colon distal to an ileocolic intussusception are presented. Two cases were associated with attempted hydrostatic reduction of the intussusception, while the other was discovered at operation. The mechanism of this complication is not clear. When performing a contrast enhanced examination of the colon and there is a risk of perforation: (a) dilute water-soluble contrast medium should be used; (b) special attention should be paid to the colon distal to the intussusception; and (c) should contrast material be observed in the peritoneal cavity, the enema reservoir should immediately be lowered to the floor to siphon off the liquid from the colon.

Barium Sulfate↗
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

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

Anophthalmia in an infant of parents using LSD.

We have described a unilateral anophthalmia in an infant with normal chromosome studies born to parents who took LSD before and during pregnancy. In view of the lack of any other fetal abnormalities in this child, known to be associated with LSD, we report this case to suggest that anophthalmia may be a new drug-related defect. A complete drug history of the parents should be taken in cases of congenital abnormalities to accumulates further data, which will point conclusively to the etiology of anophthalmia and possibly other congenital defects.

Abnormalities, Drug-Induced↗
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↗
PubMed1980

Centronuclear myopathy: follow-up study of a case reported as an early onset myopathy (1966): muscle biopsies in parents and sibs.

A 21 year-old boy suffered from a congenital myopathy with predominantly proximal distribution and mild involvement of facial and oculomotor muscles. A third muscle biopsy at age 20 and a reappraisal of two previous biopsies led to the diagnosis of centronuclear myopathy. A review of about one hundred cases in the literature shows that age of onset, mode of inheritance and pathologic features may differ in large proportions. For genetic counselling investigations were performed on the patient's parents, brother and sister. All family members were clinically normal. Electromyography showed short potentials suggestive of myopathy in both parents but much more so in the patient's sister. Biopsies revealed equivocal changes, especially in mother and sister. No definitive conclusions about the mode of inheritance could be drawn in this family.

Adolescent↗
PubMed1979

Metabolic oxidation of the ethynyl group in 4-ethynylbiphenyl.

1. 4-Ethynylbiphenyl undergoes extensive metabolism in the rat and the rabbit, involving aromatic hydroxylation and oxidation of the ethynyl group. No metabolites containing the intact ethynyl group were detected. 2. In the rat unchanged 4-ethynylbiphenyl was concentrated initially in the adipose tissue. No other tissues accumulated significant amounts of radioactivity. 3. The major metabolites were the same in both the rat and the rabbit, namely 4'-hydroxybiphenyl-4-ylacetic acid (90-95% of dose) and biphenyl-4-ylacetic acid (2-10% of dose). 4. Excretion was slower in the rat than in the rabbit, probably because of greater biliary and faecal excretion in the rat. Biliary excretion and enterohepatic circulation of biphenyl-4-ylacetic acid and 4'-hydroxybiphenyl-4-ylacetic acid were demonstrated in the rat.

Acetylene↗
PubMed1979

Growth in short term primary cell cultures derived from pregnancy-dependent mammary tumors.

The behavior of cells in primary cultures derived from autonomous and pregnancy-dependent mouse mammary tumors was studied. Despite initial growth both dependent and autonomous mammary tumors produced only short-term primary cultures. Initial plating density had a marked effect on growth with only cultures plated at greater than or equal to 2 X 10(5) cells/cm2 showing any short-termed growth. Time lapse analysis showed that the lack of growth was due to failures of cytokinesis and increased death rate and intermitotic time in cultures plated at less than 2 X 10(5) cells/cm2. Using continuous label autoradiographic techniques, a partial synchronous wave of DNA synthesis was observed with newly plated and restimulated cultures. DNA synthesis reached a peak 24-48 hrs. after plating or restimulation and then dropped to low values for the next few days. Attempts to maintain the initial high rate of DNA synthesis or to induce another round of DNA synthesis by enriched media, increased serum concentrations, or other types of serum and plasma were at best only partially successful. Important hormones necessary for growth of mammary tissue in vivo may be necessary for sustained growth in vitro.

Animals↗