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Biomedical subjects

L Orcel

Publications and source records attributed to L Orcel.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

Ultrastructure of human umbilical vessels: a possible role in amniotic fluid formation?

Human umbilical vessels obtained from neonates delivered at term after uneventful pregnancies were examined by light and transmission electron microscopy, with the aim of determining whether or not their structure is compatible with possible fluid exchange between the circulating blood and Wharton's jelly. A comparison of arteries and veins showed that although these vessels have common characteristics, they differ in some elements of their fine structure. The endothelium of both vessels appeared to be highly active metabolically. In the artery, the endothelial cells often protruded into the lumen. This aspect was related to the fine filaments concentrated in the basal part of the cells. This zone, free of organelles, was absent in the venous endothelium, but here pinocytotic vesicles and Weibel-Palade bodies were more abundant. The media included the same elements but was much thicker in the arteries than in the veins. There were two cellular types: typical myocytes and myofibroblasts rich in organelles. Their cytoplasmic processes extended into the interstitial space which was occupied by a material with a loose structure, that is, material containing a well-developed ground substance at the expense of the elastic and collagen fibres. The ultrastructural features of the umbilical vessels suggest an increased endothelial permeability, and it is suggested that transfer across the umbilical vessels may play a role in the formation of amniotic fluid.

Amniotic Fluid↗
PubMedDate not supplied

[Vascular lesions of the endometrium in spontaneous abortion].

On the basis of a histological study of vascular lesions of the endometrium following 108 cases of spontaneous abortion, the authors propose the following conclusions: 1) In the first six weeks of pregnancy, early abortion results more often from a primary ovular defect than from any abnormality in the maternal environment, of endogenous or exogenous origin and capable of resulting in a lesion of the endometrium or its vascularisation. The structure of the walls of the spiral arteries of pregnancy is almost invariably normal. 2) By contrast, in late abortions, arterial lesions--and in particular fibrosis--may play a role. This occurs however when the basal arteries with a well-differentiated elastic structure are involved. The spiral arteries of pregnancy and the utero-placentar arteries are involved only by lesions of vasculitis secondary to inflammatory phenomena as a result of retention of the products of conception or by pseudo-atheromatous lesions resulting from the deposition of degenerated cyto-trophoblastic elements, but never from true arteriosclerotic lesions.

Abortion, Spontaneous↗
PubMedDate not supplied

[Anatomic pathological aspects of chronic obliterating arteriopathies of the extremities (author's transl)].

It appears that the classical concept of atherosclerosis cannot be applied indiscriminately to all cases and that it is essentially valid for the aorta and its large branches of predominantly elastic structure. When more peripheral arterial trunks are considered, those of muscular type, the lesions are in great part characterized by a dystrophic fibrosis of the media, associated with a diffuse intimal thickening and with stratified fibro-hyaline plaques narrowing the lumen; the latter are responsible for the circulatory insufficiency and gangrene. Comparative analysis of 50 surgical specimens allow us to conclude that those fibro-hyaline plaques represent progressively stratified parietal thrombi that are populated by myocytes, at the contact of which ultrastructural investigation reveals important phenomena of elastogenesis and elastolysis. Most probably, the myocytes originate from the media, through fenestration within the inner elastic membrane. These facts have more than just a purely speculative interest: they express the great plasticity of the arterial walls and their capacity of adaptation to new hemodynamic and biologic conditions. It is interesting to note that this lesion constantly presents signs of metabolic activity and structural remodeling despite its long standing caracter.

Aging↗
PubMedDate not supplied

[Use of a titrated extract of Centella asiatica in chronic hepatic disorders (author's transl)].

The authors report their preliminary results of a study of the possible therapeutic activity of a titrated extract of Centella asiatica in chronic hepatic disorders. Early results are encouraging, especially from a histological point of view, where improvement in the criteria evaluated was noted in 5 of the 12 patients treated for the longest time. These results have to be assessed in a critical manner until confirmation is obtained by complementary studies.

Adult↗
PubMedDate not supplied

[Physical state of lipids accumulated in atherosclerotic lesions (author's transl)].

The work of Small and al. concerning the physical state of lipids accumulated in atherosclerotic plaques, is analysed. This team of biophysicists studies the composition in cholesterol, cholesterol esters and phospholipids, of each type of lesion and reports it on a phase diagram, while identifying the physical state of these lipids by polarizing microscope and by X-ray diffraction. In such a way, they show that the ordinary fatty streak has a composition which situates it in the 2 phases-zone, and actually demonstrate liquid crystals of phospholipids (+ cholesterol + cholesterol esters) and oily droplets of cholesterol esters, but never cholesterol crystals. In the other types of lesions (intermediary lesions, fibrous plaques and atheromatous plaques) they find, in addition to liquid crystals and oily droplets previously mentioned, crystals of cholesterol monohydrate, which leads to 3 phases. These findings are in accord with experimental models studied by the authors, for whom the physical state of lipids plays a very important role in the formation as well as the regression of atherosclerotic plaques.

Arteriosclerosis↗