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Biomedical subjects

J Molnar

Publications and source records attributed to J Molnar.

At least 55 records · Page 3Linked to original sources
PubMed1981

A role for anti-inflammatory agents and cyclic AMP in regulating fibronectin-mediated phagocytosis.

The present study deals with the effects of anti-inflammatory drugs and agents known to elevate intracellular levels of cyclic AMP (cAMP) on plasma fibronectin-mediated (PFn) phagocytosis of radiolabeled, gelatin-coated latex particles (g-Ltx*) by inflammatory macrophages. Monolayers of casein-elicited peritoneal macrophages were preincubated with the specified agents for either 1 or 24 hrs at 37 degrees C prior to the measurements of phagocytosis in the presence of human plasma fibronectin (47 microgram/ml) and heparin (6.7 U/ml). Under these conditions, prostaglandin E1, colchicine, vincristine, and cytochalasin B were all effective in inhibiting g-Ltx* phagocytosis by macrophages in a dose-dependent fashion. More potent inhibition of phagocytosis was manifested by agents known to increase intracellular levels of cAMP in phagocytic cells. Dibutyryl cyclic AMP (dbcAMP), d,1-isoproterenol and aminophylline (10(-5) to 10(-3) M) were all effective in reducing the uptake of g-Ltx* by macrophages. The combination of dbcAMP and aminophylline acted additively. These studies demonstrate that anti-inflammatory drugs and cAMP-elevating agents exert potent inhibitory effects on fibronectin-mediated phagocytosis of gelatin-coated particles by macrophages. Thus, our system provides a suitable in vitro model for further investigations into the humoral regulation of phagocytosis of denatured collagen-coated particles and tissue debris by inflammatory phagocytic cells.

Alprostadil↗
PubMed1980

The percentage of cells in DNA synthesis in epidermoid carcinomas of the head and neck: a preliminary report.

The in vivo study of cell kinetics of squamous carcinomas of the head and neck is in its infancy. One cell kinetic parameter, the labelling index (LI), the percentage of cells actively replicating DNA, was estimated in carcinomas of the oral cavity (10), larynx (6) and pharynx(5) by an histochemical immunoglobulin technique developed recently in our laboratory: the antinucleoside antibody technique (ANIP-LI). Data from earlier experiments using autoradiography (3H-thymidine) have established that the enzyme-antibody and isotopic techniques are equivalent. The LI ranged from 1 to 30 with a mean of 13 in this group of tumors. The LI could not be evaluated for 14% (3/21) of the specimens. The 3 patients with tumors not suitable for ANIP-LI had received a full course of radiotherapy and/or chemotherapy before they had entered our study. The higher the LI of the tumor, the greater the likelihood that the surgical stage would be higher than the clinical stage, most often as a result of clinically unrecognized lymph node metastasis. However, the number of tumors sampled was inadequate for a statistical trend to be identified. The potential for the LI to be useful in the formulation of improved therapeutic strategies awaits the accumulation of more data from studies currently in progress.

Carcinoma, Squamous Cell↗
PubMed1980

Fibronectin-mediated uptake of gelatin-coated latex particles by peritoneal macrophages.

The present study demonstrates the ability of plasma fibronectin or cold-insoluble globulin (Clg) to promote the uptake of 125I-labeled, gelatin-coated latex beads (g-Ltx*) by monolayers of peritoneal macrophages (PM). The uptake of g-Ltx* by PM was enhanced by Clg in a concentration-dependent fashion and required the presence of heparin (10 U/ml) as an obligatory cofactor for maximal particle uptake. Treatment of PM monolayers with trypsin (1 mg/ml) for 15 min at 37 degrees C after particle uptake removed less than 15% of the radioactivity incorporated by the monolayers. However, a similar trypsin treatment of the monolayers before the addition of latex particles depressed Clg-dependent uptake by greater than 75%. Pretreatment of PM monolayers with inhibitors of glycolysis effectively reduced the Clg-dependent uptake of latex. Similarly, pretreatment of monolayers with either inhibitors of protein synthesis or agents that disrupt cytoskeletal elements also significantly depressed Clg-dependent particle uptake. Phagocytosis of g-Ltx* by PM in the presence of Clg and heparin was confirmed by electron microscopy. Finally, g-Ltx* could also be effectively opsonized with Clg at 37 degrees C before their addition to the monolayers. These studies suggest that the recognition of g-Ltx* in the presence of Clg required cell surface protein(s) and that subsequent phagocytosis of these particles by PM was energy dependent and required intact intracellular cytoskeleton elements. Thus, PM monolayers provide a suitable system for further studies on the function of Clg in the recognition and phagocytosis of gelatin-coated particles by phagocytic cells.

Animals↗
PubMed1978

Observations on fifty distal splenorenal shunts.

Fifty patients underwent conventional distal splenorenal shunts for bleeding esophageal varices. Five patient died within 30 days, giving an operative mortality of 10%. Three patients were lost of follow-up, but 47 patients were evaluated. Twelve patients died, 11 of liver failure, with more than half of the deaths occurring with 1 year, three fourths within 2 years, and all within 3 years after operation. Eleven patients rebled, and seven of these were among those who died. Sixteen patients had ascites prior to operation, but all responded to aggressive medical therapy. Twenty-two patients were available for study 2 or more years following operation. Eighteen (82%) are well with no encephalopathy, although the remaining four (18%) have had transient episodes of encephalopathy. Sixteen of the 18 patients judge their lifestyles to be productive. If the patient survived 24 months or longer, he had a four in five chance of living a normal life.

Adolescent↗
PubMed1976

Nuclear and polyribosomal ribonucleoprotein particles containing poly (A) in rat liver cells.

Poly(A) containing ribonucleoprotein particles were prepared from rat liver nuclei and polyribosomes. The particles have sedimentation coefficients of 14 S and 9 S, respectively. In CS2SO4 density gradients the particles banded at densities of 1.28-1.29 g cm-3. Both nuclear and polyribosomal poly(A)-RNP contain in addition to some minor polypeptides, two main polypeptides having molecular weights of 63 000 and 90 000 dalton, respectively indistinguishable from each other according to their electrophoretic mobilities.

Animals↗
PubMed1976

Autodegradation of pre-mRNA containing nuclear ribo-nucleoprotein particles. The effect of autodegradation on the double-stranded RNA sequences and on the protein composition of particles.

The quantitative changes of double-stranded RNA components of nuclear ribonucleo-protein particles containing pre-mRNA was investigated in the course of incubation of particles at 37 degrees C. The incubation of purified nuclear particles revealed the fragmentation of long double-stranded RNA sequences into shorter stretches. The presence of nuclear sap in the incubation mixture resulted in degradation of the double-stranded RNAs into acid soluble products. Autodegradation and/or ribonuclease treatment of nuclear RNP particles is accompanied by quantitative changes in the minor protein constituents of informofer.

Animals↗
PubMed1975

A proposed pathway of plasma glycoprotein synthesis.

Plasma glycoprotein synthesis in the liver occurs in a stepwise fashion. The first sugar, N-acetyl-glucosamine, is attached to the protein during the growth of the polypeptide chain on the membrane-bound ribosomes. Subsequent carbohydrates are incorporated after the completion of the protein in the lumen of the endoplasmic reticulum and Golgi apparatus. The reactions are carried out by enzymes strongly bound to the membranes. Because the glycosylation reaction occurs in the interior of the cytoplasmic tubules a permeability problem for the nucleotide sugar exists. Recent studies indicate that sugar-lipids are formed on the cytoplasmic site of the membrane and these complexes transfer the sugars across the membrane. Experimental evidence for this pathway is presented in this article.

Acetylglucosamine↗