1,721,023 research outputs found
Short Cycles of Both Static and Pulsed Electromagnetic Fields Have No Effect on the Induction of Cytokines by Peripheral Blood Mononuclear Cells
No full textPulsed Electromagnetic Fields Enhance the Induction of Cytokines by Peripheral Blood Mononuclear Cells Challenged with Phytohemagglutinin
No full textCyclic changes of sialidase in human cervical mucus
No full text1. Sialidase activity is detectable in whole cervical mucus of normal women throughout the menstrual cycle and presents cyclic variations toward endogenous and exogenous substrates. 2. The level of sialic acid bound to the mucus increases progressively till mid-cycle and declines in the post-ovulatory phase. 3. The sialidase of the mucus probably derives from different sources and its role remains speculative
The role of protease inhibitors and albumin on the membrane shedding of human erythrocytes
No full textHuman erythrocytes incubated at 37° C in a physiological solution containing divalent cations but without glucose release up to 55% of the total sialoglycopeptides of the membrane within 60 hrs. The inhibition of the release by soybean trypsin inhibitor (SbTI), trasylol and epsilon amino-n-caproic acid (EACA), suggests that proteases bound to the membrane are probably responsible for the membrane shedding. Human albumin reduces significantly the membrane proteolysis
Studies of factors regulating the ageing of human erythrocytes-IV. Influence of physiological proteinase inhibitors
No full text1. 1. The release of sialoglycopeptides from the membrane of erythrocytes incubated at 37°C in a physiological, aproteic solution containing divalent cations, but without glucose, can be correlated with the number of polymorphonuclear leukocytes (PMNL). 2. 2. Erythrocytic glycoproteins emerging in the outer environment can be cleaved by neutral proteinases unless natural inhibitors are present. 3. 3. Among the inhibitors: α2-macroglobulin, α1-antitrypsin and α2-antiplasmin, tested within the physiological range of concentrations, the α2-macroglobulin inhibits proteolysis very effectively. © 1981
Studies of factors regulating the ageing of human erythrocytes--III. Metabolism and fate of erythrocytic vesicles
No full text1. Ageing erythrocytes release vesicles the metabolism of which is unknown. 2. Human and rat erythrocytic vesicles labelled with 51Cr and injected into rats, disappear very rapidly from the circulation with half-lives from 2 to 8 min. 3. Their lifetime resembles that of liposomes encapsulating [51Cr]haemoglobin (Hb) and in both cases, liver and spleen take up considerable amounts of radioactivity. 4. These results indicate, for the first time, that vesicles released from erythrocytes are cleared at very fast rates from the circulation and suggest that this may be the reason for the absence of vesicles in the plasma in vivo
Cytokine production by human peripheral blood mononuclear cells exposed to low-frequency electromagnetic field
No full textWe evaluated the effects of a 50-Hz pulsed electromagnetic field with a peak magnetic field of 3 mT on the production of cytokines by resting peripheral blood mononuclear cells. Our results demonstrate no modification of interleukin-1β, interleukin-2, or interleukin-6 levels, evaluated 0, 24, and 48 h after exposure, compared with sham-exposed cells. Proliferation indices were also practically unchanged, suggesting the absence of any activating effect of the electromagnetic field. Indeed, concentrations of tumor necrosis factor-α and interferon-γ, evaluated during the same period after 12 h of EMF exposure, were significantly lower than those measured in supernatants of control cells. This was confirmed by evaluation of both cytokines during a 24-h exposure period and 24 h thereafter, in the supernatants of exposed and sham-exposed cells. Comparison between tumor necrosis factor-α biologic activity and the cytokine antigen present in our samples showed strong and reproducible correlation values, suggesting the absence of qualitative differences in this protein due to either proteolytic activity or electromagnetic field
Human beta-interferon incubated with muscle homogenate is protected by albumin but not by proteinase inhibitors
No full textThe scarce bioavailability of beta-interferon (IFN-beta) after intramuscular administration is probably due either to the binding of IFN-beta to interstitial matrix, or to lymphatic absorption and/or to local breakdown by lysosomal proteinases from muscle. In this work, we first showed that after intramuscular injection, the apparent bioavailability of natural human IFN-beta is about 10% of that of recombinant IFN-alpha 2 and then we evaluated the effects of proteinase inhibitors and albumin on IFN-beta incubated at 37 degrees C with muscle homogenate. IFN biological activity decreased spontaneously by about 20% after incubation for 6 hr at 37 degrees C in Hanks' solution, but it was almost completely lost after incubation with muscle homogenate. Proteinase inhibitors (alpha 1-antitrypsin, alpha 2-macroglobulin, aprotinin, soybean trypsin inhibitor, leupeptin, EP-459, and EP-475) failed to block the inactivation of IFN-beta by muscle proteinases, whereas albumin exerted a partial but consistent protection
Bulk preparation of hepatic binding protein
No full textA method for the extraction in the cold of hepatic binding protein using a novel combination of detergents, namely 1% Na urso deoxycholate and 5% Tween 80 in the extraction buffer, which allows a significantly higher recovery of lectin than 1% Triton X-100 is described. It is noteworthy that this lectin preparation can be maintained in solution for over a month and can be used in vitro and in vivo
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