Stimulation of neutrophils by tumor necrosis factor

Human recombinant tumor necrosis factor (TNF) was shown to be a weak direct stimulus of the neutrophil respiratory burst and degranulation. The stimulation, as measured by iodination, H2O2 production, and lysozyme release, was considerably increased by the presence of unopsonized zymosan in the reaction mixture, an effect which was associated with the increased ingestion of the zymosan. TNF does not act as an opsonin but, rather, reacts with the neutrophil to increase its phagocytic activity. TNF-dependent phagocytosis, as measured indirectly by iodination, is inhibited by monoclonal antibodies (Mab) 60.1 and 60.3, which recognize different epitopes on the C3bi receptor/adherence-promoting surface glycoprotein of neutrophils. Other neutrophil stimulants, namely N-formyl-methionyl-leucyl-phenylalanine, the Ca2+ ionophore A23187, and phorbol myristic acetate, also increase iodination in the presence of zymosan; as with TNF, the effect of these stimulants is inhibited by Mab 60.1 and 60.3, whereas, in contrast to that of TNF, their stimulation of iodination is unaffected by an Mab directed against TNF. TNF may be a natural stimulant of neutrophils which promotes adherence to endothelial cells and to particles, leading to increased phagocytosis, respiratory burst activity, and degranulation.     

Biosynthesis of serum albumin in rat liver. Evidence for the existence of `proalbumin''

1. A protein(s) of rat liver (precipitated from soluble extracts of the microsomal fraction by anti-albumin) yields albumin after limited hydrolysis by trypsin. 2. Evidence that the product of limited tryptic hydrolysis is albumin, is based upon ion-exchange chromatography, electrofocusing and peptide `mapping'. 3. The albumin `precursor' is recognized by anti-albumin and is apparently not distinguished from albumin by anti-albumin. 4. A small peptide is liberated from the presumptive albumin precursor during limited tryptic hydrolysis. This peptide is labelled by arginine, but not by leucine, lysine or methionine. 5. These results support our previous suggestion based on kinetic evidence that the albumin-like protein(s), in the anti-albumin precipitate from rat liver, is an albumin precursor.     

Effect of nucleoside 5′-di- and 5′-tri-phosphates on pancreatic ribonuclease activity

1. ADP, ATP and GDP inhibited the phosphotransferase activity, the release of cyclic nucleotides from RNA, of ribonuclease. No significant inhibition was elicited by pyrimidine 5'-nucleoside diphosphates, CDP and UDP. 2. Inhibition by ADP, AMP, adenosine, adenine, NAD and NADP was insignificant at the concentrations tested. Small inhibition was observed with high concentrations of AMP and only when soluble RNA was the substrate. 3. Inhibition by ADP was found to be ;uncompetitive'. 4. Results seem to indicate that at least for optimum inhibition the polyphosphate of the purine nucleoside is essential. They further suggest that the inhibitor acts by combining with the enzyme only when the enzyme is bound to the substrate.     

Endothelial cell adhesiveness for human T lymphocytes is inhibited by transforming growth factor-beta 1.

Recombinant human transforming growth factor-beta (TGF-beta) was found to inhibit the adhesive phenotype of human umbilical vein endothelial cells for human PBL, purified T lymphocytes, and PHA-activated lymphoblasts. TGF-beta inhibited lymphocyte attachment to resting human umbilical vein endothelial cells and also to endothelial monolayers stimulated with the pro-inflammatory cytokines TNF-alpha and IL-1 beta. Our investigations also show that the ability of endothelial cells to respond to TGF-beta by altering their adhesiveness is lost with prolonged culture of the cells. However, this loss is selective as TGF-beta inhibits cell proliferation in both early and late passage endothelial cells. These results suggest that in vivo TGF-beta may inhibit the adhesive phenotype of endothelial cells and also may limit the immunologic response occurring at the endothelial cell barrier.     

Characterization of a noncyst-forming isolate of Trichinella from a wild boar in Yugoslavia.

An isolate of Trichinella obtained from a wild boar in Yugoslavia did not form cysts in the musculature of its natural host. Subsequent inoculation into experimental hosts demonstrated that some larvae became encysted only after extended time periods, whereas others remained unencapsulated. Histological staining of larvae in the musculature demonstrated no deposition of collagen typically seen for Trichinella spiralis spiralis, Trichinella spiralis nativa, or Trichinella spiralis nelsoni. The Yugoslavian isolate, given the name of Zagreb isolate after the University where it was first studied, had low infectivity for pigs and mice. Isozyme analysis demonstrated greater homology with T. s. nelsoni than with other subspecies of Trichinella. Restriction fragment length polymorphisms and dot blot analyses further demonstrated the distinctive nature of this isolate. These results suggest that lack of cyst formation might be characteristic of isolates other than those designated Trichinella pseudospiralis and that this character might be important in the classification of Trichinella.     

Effect of water stress on the chloroplast antioxidant system: I. Alterations in glutathione reductase activity

The effect of water stress on glutathione reductase and catalase activities was evaluated in leaf blades of field-grown winter wheat (Triticum aestivum L.). Wheat was sown at two seeding rates under both irrigated and dryland conditions. Flag leaves from dryland plants sown at 60 kilograms/hectare showed no change in either glutathione reductase or catalase activities per unit leaf area, while leaves from the basal portion of the canopy exhibited a 273% increase in glutathione reductase activity and a 60% increase in catalase activity. Glutathione reductase activity in dryland plants sown at 120 kilograms/hectare increased 25% in flag leaves and 225% in basal leaves. No change in catalase activity was observed in either flag or basal leaves from these same plants. The increase in glutathione reductase activity in response to water stress was observed when activity was expressed on either a per unit leaf area, protein, or chlorophyll basis. No change in catalase activity was detected when enzyme activity was expressed on a protein basis.     

Diabetes in Mice after Coxsackie B4 Virus Infection

The intraperitoneal inoculation of CD₁ mice with Coxsackie virus B₄ resulted in the raising of blood sugar levels to diabetic values 12 days after the administration of the virus. Serum insulin remained inappropriately low. Light microscopy changes in the islets of Langerhans showed mononuclear cell infiltration of the islets and marked degranulation of the β cells. The acinar tissue appeared to be little changed. It is concluded that Coxsackie B₄ virus may cause a diabetic state compatible with islet cell damage.     

Utilization of mevalonate by aorta for the synthesis of medium-chain n-fatty acids (C8, C10) and acylglycerols

[2-14C]Mevalonate was incorporated into acylglycerols by bovine aorta. The majority of the radioactivity was found in diacylglycerols. Hydrolysis, followed by analysis by thin-layer chromatography, paper chromatography, gas chromatography, and gas chromatography-mass spectrometry showed that the radioactivity was greatest in the medium-chain n-fatty acids, caprylic (C8) and capric (C10) acids. Triacylglycerols and diacylglycerols have important functions in the maintenance of the metabolic integrity of organs and their constituent cells. Therefore, medium-chain fatty acids may play significant roles, such as solubilization and transport of cholesterol and regulation of metabolism, as constituents of diacylglycerols. The results suggest that the trans-methylglutaconate shunt of mevalonate metabolism functions in the aorta.