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Biomedical subjects

B Nusgens

Publications and source records attributed to B Nusgens.

72 records · Page 4Linked to original sources
PubMed1983

Accumulation of several basement membrane proteins in glomeruli of patients with preeclampsia and other hypertensive syndromes of pregnancy. Possible role of renal prostaglandins and fibronectin.

The glomerular lesions of preeclampsia consist of swelling of endothelial cells, interposition of mesangial cells and matrix between the endothelial cells and the glomerular basement membrane, and organization of subendothelial deposits of incompletely characterized material. Fibrin and immunoglobulins have previously been localized to these deposits. Laminin, a large basement membrane glycoprotein, type IV collagen, fibronectin, and a basement membrane proteoglycan were found in moderate amounts in the mesangium and prominently in the thickened glomerular capillary walls of patients with preeclampsia or other hypertensive syndromes of pregnancy. Fibrin showed the same pattern of distribution as that of fibronectin. The material deposited in the subendothelial layer of the capillary loops thus consists not only of plasma-derived proteins but also structural components of the glomerular basement membrane and of the mesangial matrix. Type I collagen deposits were demonstrated only in mesangium of pregnant patients with chronic or recurrent hypertension. Glomerular epithelial and mesangial cells synthesize in vitro the basement membrane proteins that accumulate in glomeruli of pregnant hypertensive patients. We have tested the influence of some of the pathophysiologic changes occurring during preeclampsia on the biosynthesis of collagen by rat glomerular epithelial and mesangial cells. Addition of indomethacin to the cultures transiently inhibited the synthesis of prostaglandins (PGE2) and of collagen. Addition of exogenous fibronectin to the media stimulated the production of collagen by mesangial and epithelial cells. Alterations in the metabolism of prostaglandins and the increased deposition of fibronectin observed during preeclampsia could thus play a pathogenic role in the accumulation of basement membrane proteins in glomeruli of these patients.

Basement Membrane↗
PubMed1980

Extraction and translation of collagen mRNA from fetal calf skin.

RNA was extracted from fetal calf skin by two different procedures, using phenol or guanidine hydrochloride. Poly(A)-rich RNA was separated by oligo(dT)-cellulose affinity chromatography and was further fractionated by sucrose density gradient centrifugation. When translated in an optimized wheat germ extract cell-free system, unfractionated guanidine-hydrochloride-extracted poly(A)-rich RNA directed the synthesis of two collagenase-sensitive protein bands, while phenol-extracted poly(A)-rich RNA with a sedimentation coefficient higher than 25 S was the only fraction to direct the same synthesis. On the basis of their electrophoretic mobility on a sodium dodecylsulfate/urea/polyacrylamide gel, these proteins were identified with procollagen alpha 1(I) and procollagen alpha 2. Inhibition of translation by phenol-extracted poly(A)-rich RNA with a sedimentation coefficient lower than 25 S was also observed. Guanidine-hydrochloride-extracted poly(A)-rich RNA from fetal skin directed the synthesis of three distinct collagenase-sensitive proteins in the micrococcal-nuclease-digested rabbit reticulocyte cell-free system; these seemed to correspond to procollagen alpha 1(I), procollagen alpha 2 and procollagen alpha 1 (III).

Animals↗
PubMed1977

Interaction between collagen type I and type III in conditioning bundles organization.

Type I and type III collagen extracted from skin was purified by differential salt precipitation and chromatography. By heating to 37 degrees, type I formed after a lag phase a floppy and opalescent gel of high optical density and type III formed more rapidly a translucent and rigid gel of low optical density. Addition of type III to type I resulted in formation of gels of reduced optical density and lag phase related to the proportion of type III added. Phase contrast and scanning electronmicroscopy demonstrated the formation of thick bundles of type I, thin fibers of type III and bundles of intermediate size related to the proportion of type III. The relationship between collagen type and bundle architecture might prove most significant in conditioning the mechanical properties of the connective tissues in normal and pathological conditions.

Amino Acids↗
PubMed1976

Bone in dermatosparaxis. I. Morphologic analysis.

Normal (N-) calf bone consists of lamellae regularly spaced and oriented parallel to the periosteum. The lamellae increase in thickness from the periosteum to the medullary cavity, by apposition of layers of cells and a calcifying matrix on either side of a hypercalcified primer. In the dermatosparactic (D-) bone, the hypercalcified primer is barely visible and the cells are irregularly arranged within the lamellae. The poorly defined vascular spaces are partly filled with an acellular calcified material. In the D-bone, the collagen fibers are sparse and radiate from the vascular space, while in the N-bone they are abundant and laid down concentric with the blood channels. In the D-bone, only a few weeks old, the outer lamellae are radially oriented with respect to the medullar cavity, while haversian remodeling already occurs in the inner part of the diaphysis. At 6 months, the inner half of the diaphysis is made up of normal haversian secondary bone, while the outer half is made up of radial lamellae. The alteration of the mechanical properties of procollagen fibers in the D-bone might be responsible for its defective organization. A resistant fibrous framework, therefore, seems required to ensure the spatial organization of the cells in the calcifying matrix and to maintain its cohesion.

Age Factors↗
PubMed1976

Bone in dermatosparaxis. II. Chemical analysis.

Physical and chemical analysis of the organic matrix of dermatosparactic (D-) bone was performed to evaluate the implication of an alteration in the mechanical properties of procollagen fibers in the process of calcification. The D-diaphyseal bone contained less collagen and more hydroxyapatite than normal (N-) calf bone. Fractionated by centrifugation in a density gradient, D-bone was found to be composed of more than 80% weight of a highly calcified fraction while N-bone of the same age contained only 37% of this fraction. As compared to N-bone, the amount of organic matrix per unit volume of D-bone was increased in the least calcified fractions and reduced in the most mineralized ones. The newly formed matrix of D-bone contained an amount of collagen similar to the N-bone while the concentration of other glycoproteins was higher. Calcification was accompanied, in both types of bone, by a progressive reduction of glycoproteins and collagen; the diminution of collagen was higher in D- than in N-bone. The presence in D-bone of procollagen fibers with altered mechanical properties might be responsible for an excess of glycoproteins in the newly formed matrix. Calcium salt deposition in this matrix and progressive distension of the fibrous framework are two possible mechanisms by which hypercalcification of D-bone occurs.

Amino Acids↗
PubMedDate not supplied

Aortic collagen biosynthesis during renal hypertension, pregnancy and hypertension during pregnancy in the rat.

The synthesis and deposition of collagen and other proteins has been measured in the aorta of the rat by radiolabeling in short term organ culture. Under these conditions, the synthesis of collagen and other proteins is linear for at least five hours. Autoradiography demonstrates a labeling in all cell layers and protein deposition in the extracellular matrix. Hypertension was induced by renal ischemia using Goldblatt's technique. The synthesis and deposition of collagen was stimulated in aorta from the first week of hypertension and in pregnancy, and was even more increased in hypertensive pregnant animals. Reserpine suppresses the rise in blood pressure in operated animals and prevents these modifications.

Animals↗