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Biomedical subjects

J Varga

Publications and source records attributed to J Varga.

At least 253 records · Page 14Linked to original sources
PubMed1987

Lack of amyloid in abdominal fat aspirates from patients undergoing long-term hemodialysis.

Recent reports describe the carpal tunnel syndrome (CTS) due to amyloid infiltration of the beta 2 microglobulin protein as a frequent complication of long-term hemodialysis. Carpal synovial and cystic bone lesion amyloid deposits have been reported; however, the extent of systemic amyloid deposition has not been determined. We examined 30 patients undergoing long-term hemodialysis for CTS and performed abdominal fat tissue aspiration for amyloid staining to evaluate the presence of systemic amyloid disease. In this group, CTS was frequent (37%) and its prevalence correlated with the duration of hemodialysis. In all patients, the abdominal fat tissue, stained with Congo red, was negative for amyloid deposits. These results confirm that CTS is a frequent complication of long-term hemodialysis; however, in this study, no detectable amyloid deposits were found in abdominal subcutaneous fat tissue. Thus, abdominal fat aspiration may not be a reliable screening test for hemodialysis-associated amyloidosis.

Abdomen↗
PubMed1986

Stimulation of normal human fibroblast collagen production and processing by transforming growth factor-beta.

Transforming growth factor-beta (TGF beta) a growth factor with diverse effects on cellular growth and metabolism, caused dramatic stimulation of total protein and collagen synthesis by confluent normal human dermal fibroblasts in culture in a dose-dependent manner. Gel electrophoresis of the newly synthesized macromolecules from the culture media of TGF beta treated cultures demonstrated accelerated procollagen processing. These results indicate that TGF beta is capable of qualitatively and quantitatively influencing the biosynthesis of matrix molecules by fibroblasts, and raise the possibility that TGF may play a role in the development of normal and pathologic fibrogenesis.

Animals↗
PubMed1986

Development of severe limited scleroderma in complicated Raynaud's phenomenon after limb immobilization: report of two cases and study of collagen biosynthesis.

We describe 2 patients with Raynaud's phenomenon who developed severe sclerodermatous changes after immobilization. The scleroderma was confined to the immobilized limb. Histologic examination of tissue samples of the affected skin showed mononuclear cell infiltrates and marked collagen deposition in the dermis and subcutaneous adipose tissue. In vitro biosynthetic studies demonstrated a dramatic increase in collagen production by cultures of involved skin from one of the patients. These results suggest that immobilization resulted in activation of dermal fibroblasts (perhaps mediated by inflammatory cells) and in the subsequent development of fibrosis in both of these patients.

Adult↗
PubMed1986

The induction of accelerated murine amyloid with human splenic extract. Probable role of amyloid enhancing factor.

Amyloid enhancing factor (AEF) is derived from the tissues of pre-amyloidotic and amyloidotic animals and, when transferred, greatly accelerates amyloid induction in the recipient murine models. It has also been reported that similarly accelerated amyloid induction can be achieved in mice by injection of human splenic homogenates from patients with amyloidosis. The present study has attempted to characterize further the mechanism of this "heterologous transfer of amyloid". Treatment of mice with the "tissue homogenate" or the "AEF extract" of AA-, AL- and A prealbumin-laden human spleens followed by daily subcutaneous casein injections induced amyloidosis in an accelerated fashion. The resultant amyloid deposits in mice had strongly positive immunohistochemical reactions with anti-mouse AA, and negative reaction with anti-human AA or anti-human prealbumin. The results lend support to the idea that accelerated amyloid induction in the recipient mice is unlikely to be due to transfer of human amyloid substance, but rather to formation of "native" murine amyloid under the influence of a human AEF factor similar to or identical with AEF described in mouse-to mouse transfer models.

Amyloid↗
PubMed1985

Peptide neurotoxins from fish-hunting cone snails.

To paralyze their more agile prey, the venomous fish-hunting cone snails (Conus) have developed a potent biochemical strategy. They produce several classes of toxic peptides (conotoxins) that attack a series of successive physiological targets in the neuromuscular system of the fish. The peptides include presynaptic omega-conotoxins that prevent the voltage-activated entry of calcium into the nerve terminal and release of acetylcholine, postsynaptic alpha-conotoxins that inhibit the acetylcholine receptor, and muscle sodium channel inhibitors, the mu-conotoxins, which directly abolish muscle action potentials. These distinct peptide toxins share several common features: they are relatively small (13 to 29 amino acids), are highly cross-linked by disulfide bonds, and strongly basic. The fact that they inhibit sequential steps in neuromuscular transmission suggests that their action is synergistic rather than additive. Five new omega-conotoxins that block presynaptic calcium channels are described. They vary in their activity against different vertebrate classes, and also in their actions against different synapses from the same animal. There are susceptible forms of the target molecule in peripheral synapses of fish and amphibians, but those of mice are resistant. However, the mammalian central nervous system is clearly affected, and these toxins are thus of potential significance for investigating the presynaptic calcium channels.

Amino Acid Sequence↗