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R Kisilevsky

Publications and source records attributed to R Kisilevsky.

At least 91 records · Page 5Linked to original sources
PubMed1987

Comparison of the stimulation of glycosaminoglycan synthesis in cultures of mononuclear cells from blood and of fibroblastic cells.

A small molecular weight factor, derived from bovine bone ('matrigenin'), stimulated glycosaminoglycan and proteoglycan synthesis of cultured human fibroblastic cells but not of mononuclear cells from human blood. However, proteoglycan synthesis and secretion by the mononuclear cells was stimulated by the addition of concanavalin A. The proteoglycan from the concanavalin-A-stimulated mononuclear cells was of smaller molecular weight than the proteoglycan from the 'matrigenin'-stimulated fibroblastic cells. The major increase in proteoglycan synthesis and secretion occurred much later during the culture period for concanavalin-A-stimulated mononuclear cells than for 'matrigenin'-stimulated fibroblastic cells.

Cells, Cultured↗
PubMed1987

Sulfated glycosaminoglycans in Alzheimer's disease.

Using the sulfated alcian blue and alcian blue-MgCl2 techniques for demonstrating sulfated glycosaminoglycans (GAGs), we have shown sulfated GAGs to be associated with the amyloidotic lesions of Alzheimer's disease, the neuritic plaques, the neurofibrillary tangle, and the congophilic angiopathy. To determine how specific these findings are to Alzheimer's disease, other neurologic disorders with neurofibrillary tangles and filamentous inclusions were examined. These included progressive supranuclear palsy, Pick's disease, subacute sclerosing panencephalitis, and postencephalitic parkinsonism. Sulfated GAGs were not demonstrated in the neurofibrillary tangles or filamentous structures in any of these disorders. The relationship of GAGs to the pathology of Alzheimer's disease is discussed as is their possible importance in determining the characteristic morphology of the amyloidotic lesion.

Alzheimer Disease↗
PubMed1987

From arthritis to Alzheimer's disease: current concepts on the pathogenesis of amyloidosis.

Amyloid is a generic term referring to a group of diverse but specific extracellular protein deposits which all have common morphologic properties, staining characteristics, and x-ray diffraction and infrared spectra. This review considers the new classification of amyloids, based on the underlying peptides forming the protein fibril, and their diversity. The pathogenesis of inflammation-associated amyloid and its relationship to high density lipoprotein metabolism is examined in detail. The lessons learned from models of inflammation-associated amyloid are extended to the other amyloids (e.g., Alzheimer's disease), and potential reasons for the common structural properties of all amyloids are explored.

Alzheimer Disease↗
PubMed1987

Sulfated glycosaminoglycans: a common constituent of all amyloids?

In the present investigation, we analyzed whether sulfated glycosaminoglycans are a common constituent in many different types of amyloid. Serial sections of amyloidotic tissue were stained for the presence of: (a) amyloid by using Congo Red, and (b) glycosaminoglycans by using both the sodium sulfate Alcian blue method and Alcian blue, pH 5.7, with varying concentrations of magnesium chloride. Our results show that sulfated glycosaminoglycans are always associated anatomically with amyloid deposits regardless of the nature of the protein deposited. Sulfated glycosaminoglycans were found in tissues containing AA, AL, inherited cutaneous amyloid, and senile cardiac amyloid (prealbumin). Additionally, we provide evidence that sulfated glycosaminoglycans are closely associated with the amyloid of medullary carcinoma of the thyroid (prothyrocalcitonin), and neuritic plaques, neurofibrillary tangles, and congophilic angiopathy in Alzheimer's disease. It is postulated that these sulfated glycosaminoglycans can influence the folding of diverse proteins such that all forms of amyloid show a significant beta-pleated sheet component.

Amyloid↗
PubMed1987

A close ultrastructural relationship between sulfated proteoglycans and AA amyloid fibrils.

Two cationic reagents, Ruthenium red (RR) and Cuprolinic blue (CB), were used to assess the morphologic and structural relationship between sulfated proteoglycans and AA amyloid fibrils in amyloidotic spleen and liver, and in isolated fibril preparations. Amyloidotic tissue fixed in the presence of RR showed RR granules, measuring 15 to 25 nm in diameter, over areas of electrondense fibrils. In isolated fibril preparations, RR granules were specifically localized on amyloid fibrils. Amyloidotic tissue fixed in the presence of CB at 0.1 M and 0.7 M MgCl2 showed both granule and filamentous (50 to 90 nm in length) staining only over areas of amyloid fibrils. This same staining localization was also seen in isolated fibril preparations. The RR and CB granules and filaments, are believed to represent proteoglycan monomers with the glycosaminoglycan chains collapsed onto the protein core. The persistent CB staining at 0.7 M magnesium chloride suggested that highly sulfated proteoglycans were present. The glycosaminoglycan moiety has previously been identified as heparin/heparan sulphate. The intimate structural relationship between sulfated proteoglycans and AA amyloid fibrils, both in situ and in isolated fibril preparations, further suggests that these highly negatively charged molecules may have an important role in the pathogenesis of amyloidosis. Several pathogenetic scenarios are suggested.

Amyloidosis↗
PubMed1987

Electrophoresis of glycosaminoglycans isolated from normal human plasma. Direct evidence for the presence of a heparin-like molecule.

It has frequently been suggested that there may normally be small quantities of heparin in human blood, but amounts so small that their direct demonstration is not possible by available methods [1-4]. In this communication, we provide direct electrophoretic visualization that heparin or a closely related substance, is present in normal human plasma. After isolating glycosaminoglycans (GAGs) from 2-3 mls of plasma, a modification of the discontinuous high voltage electrophoretic method developed by Cappelletti et al. was used to successfully separate and identify the GAGs present in six normal adults (4 men and 2 women). In each case, in addition to chondroitin-4-SO4, chondroitin-6-SO4, and heparan-SO4, we were able to show the presence of a band which corresponds to that of heparin.

Electrophoresis, Cellulose Acetate↗
PubMed1987

Characterization of tissue and plasma glycosaminoglycans during experimental AA amyloidosis and acute inflammation. Qualitative and quantitative analysis.

Qualitative and quantitative methods were used to determine changes in glycosaminoglycans (GAGs) in the spleen and plasma during initial stages of experimental amyloidosis and acute inflammation. GAG deposition in the spleen during the early stages of amyloidosis consists of a 16-fold heparin and heparan sulfate increase. Though splenic weights do increase during protracted inflammation only minor changes arise in splenic GAGs in the absence of amyloid deposition. An overall increase in plasma GAGs, consisting of a 4.5-fold chondroitin-4-sulphate increase, occurred at the time of GAG deposition in the tissues (spleen, liver) and probably accounts for the minor GAG changes seen in the spleen during inflammation. The time course of splenic heparin/heparan sulfate increase during amyloid deposition coincides with the histochemical changes previously described. Plasma GAG changes follow a pattern similar to that of acute phase protein reactants. The results suggest that GAG metabolism, in particular heparin/heparan sulfate, are intimately involved in the process of AA amyloidogenesis.

Acute Disease↗
PubMed1986

Rapid changes in glucose metabolism following the administration of ethionine: its role in regulating hepatic protein synthesis.

The relationship between the changes in portal glucagon, insulin, glucose, and hepatic protein synthesis were investigated during ethionine intoxication. There was a 50% decrease in blood glucose, a seven-fold increase in portal glucagon and a 90% increase in portal insulin, all of which coincided temporally with the inhibition of hepatic protein synthesis. When reversal of ethionine intoxication was initiated with adenine it simultaneously restored blood glucose, insulin, glucagon, and protein synthesis. Protein synthesis could not be adequately restored by glucose, but in this case hepatic ATP levels did not increase. In addition, glucose given by stomach tube prior to ethionine did not prevent the action of ethionine, though it did maintain plasma glucose levels and prevented the decrease in plasma insulin and increase in plasma glucagon. These results show that in vivo regulation of hepatic protein synthesis during ethionine intoxication is not likely to be mediated by portal insulin, glucose, and glucagon.

Adenine↗
PubMed1985

Temporal relationship between glycosaminoglycan accumulation and amyloid deposition during experimental amyloidosis. A histochemical study.

The temporal relationship between glycosaminoglycan (GAG) accumulation and amyloid deposition was determined in two models of amyloid induction. In the first model amyloid was induced rapidly using amyloid-enhancing factor and AgNO3 as an inflammatory stimulus. In the second model amyloid was induced by daily injections of azocasein. Congo red staining was used to demonstrate amyloid, and both the sulfated Alcian blue and Alcian blue (pH 5.7)-MgCl2 methods were used to demonstrate GAGs. In the rapid model, amyloid was first detected in the splenic perifollicular areas 36 hours after induction. The initial presence of GAGs was also seen at 36 hours and in the exact locale where the amyloid was found. Amyloid was first seen in the liver about the central veins at 48 hours. GAGs in the liver appeared coincidentally with and in the same location as the amyloid. In the traditional model (azocasein injections) amyloid did not appear in the spleen until day 6 to 7, again with coincidental GAG deposition. The present study shows that amyloid-associated GAGs appear in the tissues together with the AA protein and are not a function of the tissue type. The appearance of the GAGs is also not a function of the nature of the inflammatory agent or its length of action but appears to be part of the process involved in the deposition of the AA protein.

Amyloid↗
PubMed1984

Ribosome conformational changes associated with protein S6 phosphorylation.

The relative accessibility of rat liver ribosomal proteins to reductive methylation was examined using ribosomes with unphosphorylated, and extensively phosphorylated S6. Comparison of the results indicated that proteins S3, S4, S7, and S23/24 of the small subunit, and proteins L9, L10, L12, L18, L27, L34, and L36 are involved in a ribosomal conformational change.

Animals↗
PubMed1984

Cyclic AMP binding activity in liver supernatants during acute ethionine intoxication.

There is a significant increase in hepatic cAMP binding activity 4 hr following ethionine intoxication. This activity is localized to the 100, 000 g supernatant. The binding of cAMP by the 100, 000 g supernatant of controls can be increased to experimental levels simply by dialysis. The increased binding activity seen during ethionine intoxication can be reversed by the administration of adenine. Neither S-adenosyl ethionine, S-adenosyl methionine, S-adenosyl homocysteine, nor AMP compete effectively with cAMP for the binding protein. Increasing ADP concentrations stimulates cAMP binding whereas increasing ATP concentration inhibits cAMP binding. At concentrations seen during ethionine intoxication the effects of ADP and ATP were equal but opposite in direction.

Adenine↗
PubMed1984

Hepatic adenylate cyclase and phosphodiesterase activity during acute ethionine intoxication.

Four hours after the administration of ethionine and in the face of an 80-90% depletion of hepatic ATP there is a twofold increase in cAMP. This increase in cAMP is shown not to be effected by a reduction in phosphodiesterase activity. Both the low Km and high Km forms of the enzyme retain their activity. The purification of liver plasma membranes is not affected by ethionine. There is a significant 20% increase in plasma membrane adenylate cyclase activity following acute ethionine intoxication. This was demonstrable using either ATP or 5'-adenylyl-imidodiphosphate as substrates. The plasma membranes, isolated in the presence of Ca2+, have a 20-fold higher basal adenylate cyclase activity then previously reported and are not further stimulated by GTP or NaF. A modified protocol for isolating cAMP from the adenylate cyclase reaction is described.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

Are elevated serum amyloid A levels and amyloid-enhancing factor sufficient to induce inflammation-associated amyloid deposition?

During inflammation-associated amyloidosis two coincident factors, serum amyloid A (SAA) and amyloid-enhancing factor (AEF) are apparently necessary for amyloid A (AA) deposition. It is shown by passive transfer of cytokines, which stimulate SAA production, and AEF that these are not sufficient. A further factor(s) is necessary, which stems from the acute inflammatory response. Potential candidates are serum or tissue glycosaminoglycans.

Amyloidosis↗
PubMed1983

Ribosome topography in baby hamster kidney cells infected with Sindbis and vesicular stomatitis viruses.

The topography of polysomal ribosomes in mock-infected and in Sindbis virus- and vesicular stomatitis virus-infected BHK cells was investigated using a double, radioactive labelling technique. Ribosomal proteins in intact polysomes were surface labelled by reductive methylation using [14C]formaldehyde. Following removal of ribosomal RNA, proteins were denatured in 6 M guanidine and labelled with [3H]borohydride. Labelled ribosomal proteins were separated by electrophoresis in two-dimensional gels and the 3H/14C ratio for each ribosomal protein was taken as an index of its relative surface exposure in intact ribosomes. Comparison of the ratios for individual ribosomal proteins in Sindbis virus-infected vs. control polysomes indicated that proteins L7, L8, L17, L26 and S19 became more 'buried' and others such as L4, L29, L36, S2 and S26 became more 'exposed' in infected cells. Most of the topographical alterations occurred in the large ribosomal subunit. In contrast, infection of BHK cells with vesicular stomatitis virus induced little or no topographical alteration.

Animals↗
PubMed1983

Kinetics of amyloid deposition. I. The effects of amyloid-enhancing factor and splenectomy.

It has long been recognized that amyloid AA deposition occurs in two phases, a predeposition and a deposition phase. The deposition phase has two distinct periods, a period of rapid deposition followed by a plateau stage. This kinetic pattern is seen in both liver and spleen and in animals in which the appearance of AA is accelerated by the administration of amyloid-enhancing factor. Amyloid-enhancing factor recipients have a shorter lag period before AA deposition is evident, but the kinetics of deposition and tissue level attained are similar to that seen in nonrecipients. It is also demonstrated that amyloid-enhancing factor activity may be generated in the liver of splenectomized animals.

Amyloid↗
PubMed1983

Kinetics of amyloid deposition. II. The effects of dimethylsulfoxide and colchicine therapy.

Amyloid (AA) protein, when deposition begins, is deposited in two stages--a rapid deposition period of 2 weeks and a plateau stage. The effect of dimethylsulfoxide (DMSO) and colchicine therapy on the kinetics of amyloid deposition was dependent on the stage of the disease at which therapy began. If given during the rapid deposition period, colchicine delayed the increase in amyloid but did not abolish it. Eventually, splenic and liver amyloid reached the level seen in untreated animals. On the other hand, DMSO given during the rapid deposition period led to significant resorption of both splenic and liver amyloid. By contrast, colchicine and DMSO given after the rapid deposition period were essentially without effect in promoting amyloid resorption. These results correlated well with the serum levels of SAA, the putative AA precursor. Colchicine given during the period of rapid AA deposition caused a transient decline in SAA levels, which eventually returned to levels seen in untreated animals. DMSO given during the rapid deposition period rapidly abolished the high SAA levels and maintained it at a level seen in normal animals. Both colchicine and DMSO therapy, if instituted after the rapid amyloid deposition period, failed to reduce SAA levels significantly below that of untreated controls.

Amyloid↗
PubMed1982

Further characterization of amyloid-enhancing factor.

Amyloid-enhancing factor (AEF) is a transferable activity that in CBA/J mice reduces the induction time of splenic amyloid deposition to 48 hours. Azocasein, or AgNo3, can induce AEF in the spleen and liver. In the liver several subcellular organelles possess this activity. This is likely due to AEF's adherent properties. AEF is most effective when given by the intravenous route. After intravenous injection, AEF particulates localize to the perifollicular areas of the spleen and Kuppfer cells in the liver. The effects of AEF administration persist for at least 4 weeks. AEF can be solubilized in 4 M glycerol, is not the amyloid A protein, and is not likely to be the serum amyloid P component. The extract can be fractionated by Sepharose 4B column chromatography. The active component is of high molecular weight, and tentative identification by disc electrophoresis has been made.

Amyloid↗