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Biomedical subjects

I Joris

Publications and source records attributed to I Joris.

54 records · Page 3Linked to original sources
PubMed1980

Microcirculatory changes in posttraumatic pigmented villonodular synovitis.

The synovium from a case of pigmented villonodular synovitis was examined by light and electron microscopy. The hyperplastic villous processes were found to contain, besides many blood vessels, a dense population of phagocytic cells actively engulfing and digesting the erythrocytes; some of their phagosomes ("siderosome") contained iron-laden micelles sometimes arranged in a crystalline lattice. The synovial vessels were remarkable in two respects: first, there was evidence of endothelial breakdown; second, the basement membranes were strikingly multilayered.

Adolescent↗
PubMed1980

Platelets, fibroblasts, and inflammation: tissue reactions to platelets injected subcutaneously.

Evidence from the literature indicates that platelets contain (besides mediators of acute inflammation) factors capable of stimulating fibroblastic growth: namely, serotonin and "platelet factors" demonstrable by their effect on tissue cultures of fibroblasts. The purpose of this study was to find out whether an inflammatory and a fibroblast-stimulating effect could be demonstrated in vivo, in the rat, using a single subcutaneous injection of concentrated platelets (platelet pellet). For comparison, rat brain, heart, and kidney tissue were homogenized under sterile conditions, spun down, and injected subcutaneously. Platelet pellets caused intense edema and neutrophil infiltration; after 8 days they had assumed a spherical shape and were surrounded by typical myofibroblasts. The 30 pellets of tissue homogenates induced a much milder acute inflammatory reaction; only one (a heart pellet) induced a recognizable myofibroblast reaction. The delayed appearance of myofibroblasts around platelet pellets was probably mediated by the neutrophils, which accumulated in large amounts around platelet pellets. Using this in vivo model, a direct fibroblast-stimulating effect of platelets was not demonstrable. It is pointed out that there are analogies between cellular reactions induced by injected platelet pellets and by intravascular platelet thrombi.

Animals↗
PubMed1979

Lymphocytes and monocytes in the aortic intima--An electron-microscopic study in the rat.

In an electron-microscopic survey of the aorta in the adult rat, white blood cells were found adhering to the intima; these were invariably lymphocytes or monocytes. Similar cells were also found beneath the endothelium. Counts were not made, but published data indicate that mononuclear cells lying over or within the rat aortic intima are approximately 1 for every 9 endothelial cells. This infiltration by blood-borne cells is interpreted as a pathologic event, possibly in response to a chemical message (antigen?) originating from the underlying media.

Animals↗
PubMed1979

A myofibroblastic tumor. Infantile digital fibroma (recurrent digital fibrous tumor of childhood).

Infantile digital fibromas are distinctive tumors both clinically and morphologically. A unique light microscopic features in the presence of intracytoplasmic, spherical, eosinophilic inclusion bodies. Previous electron microscopic studies have shown these bodies to consist of fibrils; bundles of fibrils have also been described in the cytoplasm. We have examined one such tumor, confirmed earlier findings, and established that the component cells are typical myofibroblasts. The latter are a variety of fibroblasts first described in granulation tissue; they are endowed with contractile properties and are characterized ultrastructurally by bundles of fibrils containing "dense bodies" such as are found in smooth muscle cells. Since our case is identical to those previously described, we propose that this tumor be called infantile digital myofibroblastoma.

Basement Membrane↗
PubMed1978

Ultrastructure of the myocardium after pulmonary embolism. A study in the rat.

The purpose of this study was to find out whether acute massive pulmonary embolism can produce myocardial changes visible by light and electron microscopy. Ww therefore produced pulmonary embolism in rats using plastic microspheres (diameter, 15 +/- 5 mu). Two experimental protocols were used: lethal embolism, with a dose of microspheres known to kill in 3 to 15 hours (these rats were killed after 1 hour), and sublethal embolism, with a dose compatible with 100% survival (these rats were killed after 24 hours). In both groups, the left ventricle was normal. The right ventricle showed two tyes of changes: a) A distinctive lesion of the myocytes, more diffuse after lethal enbolism and different from the "zonal lesion" of shock. It consisted primarily in a localized shredding of the myofibrillar system; hence, the name shredding is proposed. Earlier stages of this lesion were represented by focal dissolution of the Z line (Z lysis). The pathogenesis of these lesions appeared to be primarily mechanical. b) Necrosis was already apparent at 1 hour and was more extensive after 24 hours. The pathogensis of the necrotic lesions is best explained by a temporary ischemia followed by delayed reflow; a possible potentiating role of endogenous catecholamines cannot be excluded. Most capilaries in the necrotic foci remained functional; this explains the rapid rate of the healing process of such lesions. A comparison is drawn between the observed foci of necrosis and the human myocardial lesions knowns as "miliary infarcts" and "myocytolysis." It is proposed that a factor common to all three is the preservation of the microcirculatory vessels and that our experimental model helps illuminate the pathogenesis of the human lesions. It is concluded that the right ventricle of acute cor pulmonale may develop cellular changes with a complex pathologenesis (mechanical, ischemic, and possibly hormonal). The nature of the changes found in our model could represent the morphologic substrate of right-sided failure; it can be correlated with the electrocardiographic abnormalities found in the comparable human condition.

Animals↗
PubMed1977

Cell-to-cell herniae in the arterial wall. I. The pathogenesis of vacuoles in the normal media.

Vacuoles were observed by light microscopy in the smooth muscle cells of the media in normal rat arteries. By electron microscopy these vacuoles were limited by two membranes; they usually contained myelin figures, a few organelles (especially mitochondria and microfilaments), and an amorphous background material that varied greatly in density. Morphologic evidence indicates that these structures arise by herniation of one smooth muscle cell into another; it is presumed that herniation occurs during contraction at weak points corresponding to areas where adjacent cells come in close contact. Such cell-to-cell herniae were mostly seen in small arteries (arterioles) with a diameter of 0.4 to 0.2 mm; however, none was found in coronary arteries of this size. This discrepancy suggests that the pathogenesis of cell-to-cell herniae is correlated not only with the caliber of the artery but also with functional demands. (Am J Pathol 87:375-398).

Animals↗
PubMed1977

Effect of occlusion on large vessels. I. A study of the rat carotid artery.

The effect of permanent occlusion on the carotid artery of the rat was studied by light and by electron microscopy. A segment between two ligatures was examined at times from 2 minutes to 1 year. Between 2 and 15 minutes after occlusion, the red blood cells adjacent to the wall formed radially arranged rouleaux; within 24 hours the endothelium disappeared, while platelets (despite the lack of flow) accumulated against the denuded elastica. This behavior of formed blood elements may have been the result of electric forces (injury potential). By 3 days, undifferentiated cells were found lining the elastica interna or free in the lumen; they apparently were derived from medial smooth muscle.In the media, by 3 days some smooth muscle cells had become necrotic, while "undifferentiated" cells appeared; strong circumstantial evidence suggested that these were smooth muscle cells which had lost their specific characteristics and had thus become dedifferentiated (a phenomenon also known to occur in striated muscle cells); by 1 month they had matured into smooth muscle, but the media from then on contained fewer cells and more collagen than normal.In the lumen, the undifferentiated cells also matured into typical smooth muscle cells from 15 days onward, while collagen and elastin appeared between them. After 1 month these cells began to accumulate droplets of fat, which thereafter increased in number (at 6 months they were associated with cholesterol clefts) and then declined. This accumulation of fat in smooth muscle cells (also seen in atherosclerosis) was interesting because it occurred in the absence of blood flow.

Arterial Occlusive Diseases↗
PubMedDate not supplied

Billroth and Penicillium.

Between 1868 and 1873, a surgeon, Theodor Billroth, performed experiments with cultures of bacteria and molds (which he believed to be two aspects of a single form of life) to investigate their role in "accidental wound diseases." Some of the cultures teemed with rounded microorganisms arranged in chains; Billroth chose to call them streptococci. He also noticed that occasionally, when Penicillium appeared in a culture, bacteria failed to grow; he suggested that Penicillum could have "modified the medium" so as to render it unsuitable for bacterial growth. This may well have been the first observation of the antibacterial effect of Penicillium. Similar experiments were performed by Joseph Lister, who noticed in 1871 that bacteria tended to kill the Penicillium, and by John Tyndall, who described in 1876 a "battle" that could be won by either party.

Antisepsis↗
PubMedDate not supplied

Increased sister chromatid exchange frequencies observed in a cohort of inhabitants of a village located at the boundary of an industrial dumping ground: phase I.

Since the mid-eighties, a sand pit located at the boundary of Mellery, a small village in Belgium, has been used as a dumping ground for industrial waste. After a particularly dry summer, many people complained of very foul smells coming from the dumping ground. An analysis of the environmental atmosphere detected alkanes and chlorinated saturated and unsaturated hydrocarbons in various concentrations. Consequently, the Belgian Ministry of the Environment requested additional measurements from the dumping site and the surrounding regions. Given the hazards and possible ill health effects associated with simultaneous exposure to low levels of many chemicals, biomarkers of personal exposure were measured in a representative group of people living in this village. The cytogenetic consequences of daily exposure to a mixture of genotoxicants were measured by the Sister Chromatid Exchange assay. The study included a group of 51 environmentally exposed persons (including 11 children) and 52 controls. A significant increase in Sister Chromatid Exchange frequency was detected among the inhabitants of the village compared to that of the control group, especially among the children living in Mellery as compared to the matched control children.

Adolescent↗