Biomedical subjects

M Bendayan

Publications and source records attributed to M Bendayan.

At least 127 records · Page 7Linked to original sources

PubMed1990

Immunocytochemical distribution of endogenous albumin and immunoglobulins in the glomerular wall of the sucrose-fed "Cohen" diabetic rat.

Endogenous circulating albumin and immunoglobulin G (IgG) molecules were revealed with high resolution over the glomerular wall of renal tissue from normoglycemic and sucrose-fed hyperglycemic Cohen rats applying the protein A-gold immunocytochemical approach. Due to the length of the experiment, the hyperglycemic animals demonstrated only minor renal morphological alterations. In spite of this, labelling for albumin and immunoglobulins in the glomerular wall showed significant differences between the normoglycemic and hyperglycemic animals. In the former, the labelings were restricted to the endothelial side of the glomerular basement membrane, while in the latter, the labelings were distributed throughout the entire thickness of the basement membrane. In addition, the hyperglycemic animals display some labelling associated with the slit diaphragms between podocytes and in the urinary space. Numerous lysosomal structures present in podocytes and mesangial cells of the hyperglycemic animals were intensely labeled for albumin and IgGs, reflecting a reabsorption activity. Dense deposits labeled for IgGs were found in the glomerular wall and mesangial regions of hyperglycemic animals corresponding to depositions of immune-complexes. These results demonstrated that in hyperglycemic conditions induced by environmental factors such as the diet, the permselectivity of the glomerular basement membrane is lost; proteins such as albumin and IgGs are not restricted by the endothelial side of the basement membrane and cross the glomerular wall leading to proteinuria. The loss of selective permeability properties of the glomerular basement membrane was found to precede the morphological changes occurring in the glomerular wall during diabetes.

Animals↗

PubMed1990

Ultrastructural distribution of glomerular basement membrane components in experimental diabetes.

To investigate possible changes in the organization of the constitutive elements of the glomerular basement membrane during diabetes we have localized type IV collagen, entactin, laminin and heparan sulfate proteoglycan on the glomerular wall of control and long-term streptozotocin-induced diabetic animals. To do so, we made use of specific polyclonal antibodies and the high resolution protein A-gold immunocytochemical technique. The morphometrical analysis of the labelling has demonstrated that each antigen displays a specific distribution in the glomerular basement membrane of normal animals. In diabetes, changes in type IV collagen were detected with an accentuation of the labelling on the endothelial side and the presence of a wider region weakly labelled on the epithelial side of the basement membrane. No differences were found in the distribution of other components in normal and diabetic conditions, beside a decrease in the labelling for heparan sulfate proteoglycan in the laminae rarae. These modifications may influence the interactions among the various basement membrane components which in turn, will affect the structural organization of the polymeric matrix of the basement membrane, leading to a loss in selective permeability.

Animals↗

PubMed1990

Distribution of endogenous albumin in the glomerular wall of proteinuric patients.

Glomerular proteinuria seems to be related, in part, to loss or impairment of the normal barrier function of the glomerular capillary wall. To investigate the functional properties of this barrier, endogenous albumin was revealed in the glomerular wall of proteinuric patients and compared with a nonproteinuric control by immunoelectron microscopy using the protein A-gold method. In the control biopsy, peaks of albumin accumulation were noted in the subendothelial area and in the inner portion of the lamina densa, with gradual tapering of the distribution toward the epithelial side of the basement membrane. The urinary space and epithelial cells were weakly labeled. In tissues from proteinuric patients, albumin was distributed throughout the entire width of the glomerular basement membrane, although the pattern of accumulation varied between patients. The urinary space showed significant labeling associated with some flocculent material. Mesangial areas were heavily labeled in tissues from both control and proteinuric patients. In the latter, lysozomes in glomerular and tubular epithelial cells also accumulated albumin, which is evidence of reabsorption. These results reveal the existence, in normal conditions, of a barrier located in the subendothelial area of the glomerular basement membrane, the loss of which, as in the idiopathic nephrotic syndrome, leads to diffuse distribution of albumin in the glomerular capillary wall.

Basement Membrane↗

PubMed1989

Distribution of endogenous albumin across the rat aortic wall as revealed by quantitative immunocytochemistry.

Endogenous albumin was revealed over thin sections of rat aortic wall, with high resolution and specificity, by applying the protein A-gold immunocytochemical technique. Gold particles, revealing albumin antigenic sites, were observed over plasmalemmal vesicles in endothelial cells and over the interstitial space throughout the thickness of the aortic wall. The distribution of the labeling in the interstitial space varied from region to region and was associated with the collagen fibers, following the orientation of the bundles. The morphometric evaluation of this labeling demonstrated a first peak in labeling intensity in the intima followed by a steep decrease with low levels in the media, and an increasing gradient towards the adventitia. In the subendothelium, a moderate labeling was observed at the base of the endothelial cells of both aortic and capillary endothelia, followed by a decreasing gradient. Ratios between the labeling density in the intima as well as in the adventitia and that in the capillary lumen (plasma albumin) revealed different concentrations of albumin in these compartments. Endogenous albumin, under steady-state conditions, is thus unevenly distributed over the interstitial spaces across the rat aortic wall, and appears associated along the collagen fibers.

Albumins↗

PubMed1989

Effect of vanadate administration on blood glucose and insulin levels as well as on the exocrine pancreatic function in streptozotocin-diabetic rats.

In the present study, streptozotocin-induced diabetic rats with their corresponding controls, were treated orally with sodium metavanadate. A gradual increase of the vanadate concentration up to 0.8 mg/ml in the drinking water, lowered the blood glucose levels of the diabetic animals to normal values without changing the insulin levels. On the other hand, vanadate did not affect the blood glucose levels of the non-diabetic animals; it did however induce lower levels of circulating insulin in these animals. The lowering of the glycaemic values of the diabetic animals was closely related to the consumption of vanadate. When the treatment was ceased, the blood glucose levels rose rapidly. The diabetic animals responded to the vanadate treatment with two sensitivities; while the large majority of the diabetic animals displayed stable normoglycaemic values, others had fluctuating values. Amylase content in the exocrine pancreas of these two subgroups of animals was studied separately and compared to that from the non-treated control and diabetic animals. The presence of amylase in the pancreatic acinar cells was assessed by the protein A-gold immunocytochemical approach and biochemical determinations. Amylase was found to be very low in the non-treated diabetic animals. Lowering of the blood glucose levels induced by the vanadate treatment restored the amylase to levels similar to those of the controls. However, vanadate-treated diabetic animals with fluctuating levels of blood glucose, demonstrated only a partial recovery of amylase. Thus, vanadate treatment was found to have a normalizing effect on blood glucose levels in diabetic animals as well as restoring amylase content in the pancreas of diabetic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗

PubMed1989

Prolactin crinophagy is induced in the estrogen-stimulated male rat pituitary.

The phenomenon of crinophagy in rat pituitary mammotrophs, or lysosomal uptake of prolactin secretory granules, was confirmed by means of double-label immunogold electron microscopy, and shown to be induced in estrogen-stimulated male rats. Rabbit antibodies to rat cathepsin D were used to label lysosomes, and to rat prolactin to label secretory granules. The pituitaries were fixed in 4% formaldehyde and 1% glutaraldehyde, embedded in Lowicryl K4M, and thin sections were exposed successively to primary antibodies, biotin-labelled second antibodies, and streptavidin-gold, with an amplification procedure for cathepsin D. Cathepsin D and prolactin were detected separately on opposite sides of the sections, using 5-nm and 15-nm gold particles. Lysosomal uptake of prolactin secretory granules was not observed in untreated control rats. It was detected in about 26% of lysosome-containing mammotroph cell sections in estrogen-stimulated rats and at 7 h after estrogen withdrawal, but fell to 14% at 24 h and to 2% at 72 h after estrogen withdrawal.

Animals↗

PubMed1989

Ultrastructural distribution of endogenous IgGs in the glomerular wall of control and diabetic rats.

Endogenous IgG molecules were revealed with high resolution EM over the glomerular wall in renal tissues sampled from short and longterm control and streptozotocin induced diabetic rats by applying the protein A-gold immunocytochemical approach. In tissues from control animals, IgG antigenic sites were revealed on the subendothelial side of the basement membrane, the epithelial side being only weakly labelled. In contrast, in longterm diabetic animals IgG antigenic sites were present throughout the entire thickness of the basement membrane, and in patches closely associated with the plasma membrane of the epithelial cells. Deposits of basement membrane-like material present in the mesangial area were also highly labelled for IgG. Numerous intensely labelled lysosome-like structures were present in the epithelial cells. Morphometrical evaluation of the distribution of the labelling over the basement membrane confirmed these observations. In control animals a peak of labelling was found at 30 nm from the endothelial cell region corresponding to the subendothelial side of the lamina densa. In longterm diabetic animals the labelling was more uniformly distributed throughout the entire thickness of the basement membrane. These data were correlated to biochemical determinations of proteinuria and IgG excretion in urine samples from the control and the diabetic animals. These results suggest that in normal conditions the lamina densa may represent the main barrier for the restriction of the passage of IgGs through the glomerular wall. Modifications at that level occur during diabetes leading to or participating in the loss of the selective permeability of the basement membrane.

Animals↗

PubMed1989

Effect of reduced energy metabolism and reperfusion on the permeability and morphology of the capillaries of an isolated rete mirabile.

The effects of reduction in energy metabolism were explored in the eel rete mirabile, an organ composed predominantly of capillaries. In vitro experiments showed that glycolysis is the major pathway of energy production in this capillary tissue, and that iodoacetate, KCN, and low PO2 in combination markedly reduce its ATP generation. When in situ energy generation was inhibited by this combination during countercurrent perfusion of the arterial and venous capillaries of the rete, an approximate doubling of the intercapillary barrier permeability for human [125I]albumin, [14C]sucrose, and 22Na was found. Structural damage was evident, but the intercellular junctions remained intact. The effect of cessation of flow for 30 minutes, followed by reperfusion, was then explored. Stasis alone altered the structure, chiefly of the venous capillary endothelium, but not the permeability of the intercapillary barrier. Stasis with a hypoxic medium containing the inhibitors of energy generation, followed by reperfusion with oxygenated control medium, resulted in a progressive breakdown of the intercapillary barrier, with a threefold to fourfold increase in solute (labeled albumin, sucrose, and sodium) permeability, evolving during early reperfusion, but no change for labeled water permeability. Morphologically, the endothelial cells, especially those in venous capillaries, showed substantial damage; they appeared vacuolated, their cytoplasm was extracted, and cytoplasmic and membrane debris were found in the lumen; intercellular junctions remained intact. Local pericyte detachment with interstitial edema also appeared. Thus, stasis and reperfusion amplified the effects of reduction in energy generation and hypoxia on both permeability and morphological change.

Anguilla↗

PubMed1989

Effect of phalloidin on structure and permeability of rete capillaries in the normal and hypoxic state.

The effects of 10(-6) M phalloidin on reperfusion-injured blood capillary structure and permeability were studied in the countercurrent perfused rete mirabile of the eel swim bladder. In the normal rete, the addition of phalloidin to the perfusion medium did not induce morphological or functional changes. When flow was arrested for 30 minutes, during which time the capillaries were exposed to inhibitors of ATP generation, and flow was then resumed with an oxygenated medium, cell membrane blebs and vacuolization, mitochondrial swelling, pericyte shrinkage, and interstitial space edema were observed. The permeability coefficients for labeled albumin, sucrose, and sodium increased to three to four times baseline values, whereas the permeability to water was not significantly modified. When the same protocol was repeated with phalloidin present in the medium throughout the experiment, the structural integrity of the endothelial cells was completely preserved and pericyte shrinkage was abolished, but interstitial space edema still occurred. The permeability to albumin, sucrose, and sodium increased only to 1.5 times baseline values, a significantly decreased increment in comparison with the experiments performed without phalloidin. We concluded that although phalloidin does not improve the capillary barrier of the normal rete, it provides protection against the structural and functional damage induced by hypoxia and reperfusion.

Air Sacs↗

PubMed1989

Lung surfactant-associated proteins and type IV collagen share common epitopes. An immunocytochemical demonstration.

Among the surfactant-associated proteins (SP-A) characterized so far, there is a group of glycoproteins 26 to 34 kDa that features collagenlike sequences near their N-terminal end. We herein report the cross-reactivity of a rabbit polyclonal antibody to EHS tumor-derived type IV collagen towards rat SP-A. Rat lung tissues were processed for the localization of both type IV collagen and SP-A by high-resolution immunocytochemistry, applying the protein A-gold technique with specific antibodies. In addition to the various basal laminae of the pulmonary tissue, the antitype IV collagen antibody labeled the surfactant material found in alveolar spaces and macrophages, as well as in type II pneumocytes. The surfactant nature of the alveolar material labeled by the antiserum to type IV collagen was confirmed by the positive labeling obtained using an antibody to SP-A. This antibody labeled specifically the alveolar surfactant material, without binding any basal laminae. Several control experiments demonstrated the specificity of each labeling. These results were further supported by immunoblot experiments on nitrocellulose membrane. These findings thus provide further support to the existence of collagenlike sequences on SP-A, and further demonstrate that this structural similarity with collagens can lead to some cross-antigenicity.

Animals↗

PubMed1989

Cytochemical demonstration of increased phospholipid content in cell membranes in chlorphentermine-induced phospholipidosis.

We recently introduced a novel cytochemical approach to high-resolution cytochemistry of phospholipids in biological tissues. The technique consists of adsorption of bee venom phospholipase A2 to colloidal gold particles (PLA2-gold complex) and subsequent application of this complex for localization of the enzyme substrate, i.e., glycerophospholipids. In the present study, this technique was applied at the post-embedding level, in both light (LM) and transmission electron microscopy (TEM), to investigate drug-induced phospholipidosis, an experimental disorder in which the lysosomal catabolism of phospholipids is inhibited. Rats received one week of daily treatment (40 mg IP/kg) with chlorphentermine (CP), a cationic amphiphilic drug known to induce phospholipidosis in several tissues. Glutaraldehyde- and osmium-fixed lung and kidney tissues from both treated and control animals, were embedded in Epon and sections processed for labeling by PLA2-gold. In CP-treated specimens the presence of large osmiophilic inclusions in several cell types of lung parenchyma and kidney cortex confirmed the onset of phospholipidosis. These inclusions were densely labeled by PLA2-gold at both LM and TEM levels. Two general types of abnormal inclusions were distinguished on the basis of their ultrastructure and labeling pattern by PLA2-gold, suggesting different content or configuration of phospholipids. Moreover, quantitative evaluation of labeling density over various membrane compartments in lung alveolar cells evidenced significantly increased phospholipid content after CP treatment. In type II pneumocytes, such increases were measured in membranes of the RER, Golgi complex, outer and inner nuclear envelope, and the basolateral and apical domains of the plasma membrane. In capillary endothelial cells, the basal and luminal domains of the plasma membrane also showed an increase in labeling density. These results further demonstrate the potential usefulness of the PLA2-gold technique for in situ ultrastructural localization of phospholipids in normal and pathological tissues.

Animals↗

PubMed1989

Electron spectroscopic imaging for high-resolution immunocytochemistry: use of boronated protein A.

In the present study we adapted electron spectroscopic imaging (ESI) for high-resolution immunocytochemistry. To accomplish this, we applied boronated protein A (B-pA) for indirect detection of specific antigenic sites using pre-embedding and post-embedding protocols. Isolated acinar cells were exposed to wheat germ agglutinin (WGA) and anti-WGA, followed by B-pA, to reveal WGA binding sites at the level of the plasma membrane. The cells were then embedded in Epon and unstained ultra-thin sections were examined by electron microscopy using the ESI mode. For post-embedding, ultra-thin sections of glutaraldehyde-fixed, Lowicryl-embedded pancreatic tissue were exposed to specific antibodies (anti-insulin or anti-amylase), followed by B-pA. The unstained sections were examined using the ESI mode. In both cases, boron was detected with high resolution either at the level of the plasma membrane of acinar cells, demonstrating WGA binding sites, or over secretory granules in pancreatic insulin-secreting cells or acinar cells, demonstrating insulin and amylase, respectively. These findings were compared to those obtained with the protein A-gold technique, and have demonstrated the analogy of both types of labeling. In addition, several control experiments assessed this novel approach. They have demonstrated the specificity of labeling and the high reactivity of B-pA, as well as its antibody-binding properties. Finally, electron energy loss spectral analysis confirmed the presence of boron in the tissue sections at sites where immunolabeling was detected. These results demonstrate that ESI is an appropriate approach for cytochemistry. Since the technique is based on detection of elements, spatial resolution is considered to be in the magnitude of 0.5 nm, which represents a major improvement in resolution over actual electron microscopic cytochemical techniques.

Animals↗

PubMed1989

Heterogenous distribution of type IV collagen, entactin, heparan sulfate proteoglycan, and laminin among renal basement membranes as demonstrated by quantitative immunocytochemistry.

Type IV collagen, entactin, heparan sulfate proteoglycan, and laminin antigenic sites were revealed on various rat renal basement membranes by use of protein A-gold immunocytochemistry. The basement membranes of the proximal and distal convoluted tubules, those of Bowman's capsule and glomerulus, and the mesangial matrix were labeled for all the antigens but to differing extents. Control experiments confirmed the specificity of these labelings. Quantitative evaluation revealed an important heterogeneity for each antigen among the various basement membranes. This heterogeneity suggests that the basement membrane components must arrange themselves in different ways, possibly to account for differences in functional properties of the various renal structures.

Animals↗

PubMed1989

Heterogeneous distribution of phospholipids in membranes along the secretory pathway in pancreatic B-cells.

The membrane content in phospholipids along the secretory pathway in rat pancreatic B-cells was studied in situ by high-resolution cytochemistry, applying the recently introduced phospholipase A2-gold technique. The gold particles were mostly associated with cell membranes, and the various types of membranes were labeled to a different extent. Quantitation of the labeling over these membranes revealed a heterogeneous distribution of the labeling across the secretory pathway. This heretogeneity occurred mainly as a progressive, decreasing gradient in the first half of this pathway, between the rough endoplasmic reticulum and the mi-cisternae of the Golgi apparatus. The labeling density remained at a lower level in the trans-most Golgi cisternae and immature secretory granule membranes, to increase in the mature secretory granule membrane, where it reached the value found in the plasma membrane. These results provide evidence that the functional heterogeneity existing across the membrane forming the secretory pathway is parallelled by substantial changes in their phospholipid content.

Animals↗

PubMed1989

Brief review on progresses in enzyme-gold cytochemistry.

Initially developed for the in situ localization of nucleic acids, the enzyme-gold approach has been extended to the detection of a large variety of biological molecules. The enzyme-gold approach, based on the highly specific interaction existing between an enzyme and its substrate, can be used both in pre-embedding and post-embedding labeling procedures. Fixation and embedding conditions for the best preservation of each particular substrate under study have to be defined. On the other hand, conditions required to adsorb purified enzymes on colloidal gold particles should be determined according to the biochemical properties of each protein. Labeling protocols must be performed taking into consideration the optimal conditions for the enzymatic activity. The enzyme-gold complexes have been shown to retain their biochemical properties and the specificity of each labeling obtained has been assessed through various control experiments. Initially applied for the demonstration of nucleic acids, the approach has been extended to the ultrastructural localization of various substrates, and in particular, more recently, glycoconjugates and phospholipids. Indeed, various glycosidase-gold complexes and a phospholipase-gold complex, applied in pre- and post-embedding labeling protocols, did specifically label plasma membranes as well as various defined subcellular compartments. In addition, the morphometrical evaluation of labeling intensities revealed differences in amounts of binding sites between compartments. Considering its versatility, simplicity and efficiency, the enzyme-gold technique provides an alternative, very valuable cytochemical tool for the localization of a variety of biological molecules at the cellular and subcellular level.

Animals↗

PubMed1989

Relationship of decreased hepatic lipase activity and lipoprotein abnormalities to essential fatty acid deficiency in cystic fibrosis patients.

Polyunsaturated fatty acids are known to affect plasma lipids and lipoproteins but there is no information on the effect of essential fatty acid (EFA) deficiency on lipoprotein composition. The purpose of this study was to characterize lipoproteins from 17 cystic fibrosis (CF) patients in relationship to their EFA status (eicosatrienoic/arachidonic acid ratio) and compare them with those of 10 healthy siblings (SIB) and of 10 unrelated controls. In 7 EFA-deficient (EFAD) and 10 EFA-sufficient (EFAS) patients, hypocholesterolemia was associated with a decrease of HDL-cholesterol and of LDL-cholesterol which was more marked in the EFAD group. Similarly, although triglyceride enrichment of VLDL, LDL, HDL2, and HDL3 with a concomitant reduction of cholesteryl esters from all particles except HDL2 was observed in both CF groups, it was more sizable in the EFAD patients. These changes led to an increase in the particle size of VLDL, LDL, and HDL2 whereas the distribution of HDL3 was skewed to smaller particles. Alterations in the apoprotein composition of particles were greater in EFAD than in EFAS. A decrease of total postheparin lipolytic activity was observed in the two groups of CF patients as well as in siblings. It was entirely accounted for by hepatic lipase (mumol FFA/ml per h) which was more severely diminished in EFAD (2.8 +/- 0.6) than in EFAS (4.4 +/- 0.7) and SIB (5.1 +/- 0.5). Although the two groups of CF children differed in terms of growth, severity of malabsorption, and vitamin E status, these data suggest that disturbance of lipoprotein concentration, composition, size, and metabolism (hepatic lipase) may be in part related to EFA deficiency. Further studies are necessary to explore the effect of EFA deficiency on hepatic lipase activity.

Adolescent↗

PubMed1988

Arrangement of desmin intermediate filaments in smooth muscle cells as shown by high-resolution immunocytochemistry.

To gain additional information about the arrangement of intermediate filaments (IF) in normal smooth muscle, fresh avian gizzard was processed for immunoelectron microscopy. The protein A-gold immunocytochemical technique was applied for the localization of desmin antigenic sites. Desmin-containing IFs were located in an axial bundle that partially surrounds the nucleus and were associated with numerous mitochondria near the poles of the nucleus. The bundle probably extends the length of the cell. Antibody labeling also showed concentrations of IF around and between cytoplasmic dense bodies (CDB) and also between CDB and membrane-associated dense bodies (MADB). The relationship between the axial bundle and the nucleus and associated mitochondria suggests that the bundle may support and define the position of these organelles in the cell. A fraying or branching of the bundle may integrate the bundle into the remaining cytoskeletal network of the cell.

Animals↗

PubMed1988

A correlated morphometric and cytochemical study on hepatocyte nucleolar size and RNA distribution during vitellogenesis.

The enzyme-gold cytochemical technique was used to label RNA in the nucleolus and rough endoplasmic reticulum (RER) of the hepatocytes of normal, male American bullfrogs (Rana catesbeiana) and in bullfrogs eight days following treatment with estradiol-17 beta. Concurrently, stereology was applied to quantitate: (1) the density of RNA labelling, and (2) changes in the size of the nucleus and nucleolus in response to estrogen treatment. In the hepatocytes from untreated frogs, specific labelling for RNA was present over the fibrillar and, to a greater extent, the granular portions of the nucleolus, and, to the greatest extent, over the RER. Following estrogen treatment, the density of RNA labelling increased over both parts of the nucleolus but was unchanged over the RER. The size of the nucleolus enlarged in response to estrogen: in combination with the increase in its RNA labelling, this suggested an increase of about 80% in the total amount of RNA in the nucleolus. Previous data on enlargement of the RER compartment, along with the present data on RNA labelling of RER, suggested that the total amount of this nucleic acid increased about 430% in this entity, in response to estrogen. However, the density of RNA labelling over the RER appears to be constant in spite of changes in the amount of RER.

Animals↗