Radioimmunoassay of antihaemophilic factor (factor VIII) antigen

A simple, precise radioimmunoassay for antihaemophilic factor (AHF, factor VIII) antigen has been developed. The technique is based upon a double-antibody solid-phase (DASP) system. This assay may serve as a specific method for differentiation between Von Willebrand's disease and haemophilia A.     

Inhibition of the activation of Hageman factor (factor XII) by aprotinin (Trasylol)

Aprotinin (Trasylol; Bayer AG, Leverkusen, Germany), a protease inhibitor resembling or identical with Kunitz' pancreatic trypsin inhibitor, is said to have anticoagulant properties, but these are not clearly defined. The present study provides evidence that one action of aprotinin is inhibition of the activation of Hageman factor (factor XII).     

Measuring tissue factor (factor III) activity in plasma

This is a method for measuring tissue factor (TF, Factor III, tissue thromboplastin) activity in plasma by using a chromogenic substrate. As pretreatment, the euglobulin fraction of plasma was prepared by removing endogenous inhibitors and heated at 60 degrees C for 3 min to remove fibrinogen. This allowed us to measure the low TF activity in plasma that could not otherwise be measured. Neither phospholipids nor coagulation factors VII, IX, X, or Xa in the samples interfere. Within-run and day-to-day reproducibility were both good. The mean value obtained by this method for normal persons was 1.02 (SD 0.91) arbitrary units/L. A markedly high plasma TF activity of 20 arb. units/L or more was observed in patients with some types of disseminated intravascular coagulation.     

Inhibition of Hageman factor (factor XII) by popcorn inhibitor

A protein derived from sweet corn or popcorn inhibits the enzymatic activity of the carboxy-terminal fragment of Hageman factor (HFf) and of ellagic acid-activated Hageman factor (HF, factor XII). Not clarified is whether the inhibitor is directed at the active site of HF. Filtration of normal plasma or purified HF through columns of popcorn inhibitor bound to agarose gels demonstrated that HF was bound to these gels and could then be eluted by buffers containing 2.0 mol/L sodium chloride. The eluted HF was in the precursor form. Thus, popcorn inhibitor appeared to attach to a point on the carboxy-terminal HFf that was distinct from the enzymatically active site of this clotting factor.     

Granulocyte-colony stimulating factor (G-CSF) and macrophagecolony stimulating factor (M-CSF) in colorectal cancer patients.

We have investigated the serum level of granulocytecolony stimulating factor (G-CSF) and macrophagecolony stimulating factor (M-CSF) and the commonly accepted tumor markers, such as carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9) in colorectal cancer. Additionally, we have defined the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and receiver-operating characteristics (ROC) curve for G-CSF and M-CSF. The serum levels of cytokines were measured in 49 patients with colorectal cancer and in 40 healthy subjects. G-CSF and M-CSF were determined using enzyme-linked immunosorbent assay (ELISA). CEA and CA 19-9 were measured by microparticle enzyme immunoassay. There were significant increases in the level of circulating G-CSF and M-CSF in the colorectal cancer patients compared to the control group. Moreover, the diagnostic sensitivity of M-CSF was higher (65%) than the sensitivity of CEA (31%) and CA 19-9 (20%). The diagnostic specificities of M-CSF and G-CSF were 95%, and the M-CSF predictive value was higher compared with the predictive value of G-CSF. These results suggest a potential role for M-CSF as a tumor marker for colorectal cancer.     

Granulocyte-colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) for sepsis: a meta-analysis

Introduction  

To investigate the effects of G-CSF or GM-CSF therapy in non-neutropenic patients with sepsis.     

Effects of epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) on human adipocyte development and function

Abstract. We investigated the effects of epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) on the differentiation of human adipocyte precursor cells and some metabolic aspects of newly formed fat cells kept in primary culture. Exposure of stromal cells from human adipose tissue to EGF (0.01–100 ng mL^-1) resulted in a dose- and time-dependent decrease in the number of developing fat cells and the activity of glycerol-3-phosphate dehydrogenase (GPDH), a marker of adipose differentiation. Continuous presence of EGF completely blocked lipid accumulation with a ED₅₀ in the range of 0.2ng mL^-1. This inhibitory action of EGF was associated with a potent stimulation of cell proliferation, up to 8-fold compared with cultures in the absence of EGF. PDGF (0.1–50ngmL^-1) and FGF (0.1–100ng mL^-1) provoked a less marked suppression of GPDH activities which was significant at concentrations of 10 ng mL^-1 and higher. A 12 day exposure to EGF of differentiated cells was followed by a suppression of GPDH and, again, a significant increase in cell number. Concomitantly, a distinct loss of cellular lipids was observed in the newly formed adipocytes. This effect could be partly explained by a stimulation of lipolysis, since EGF caused an increase of glycerol in the culture medium. Addition of PDGF or FGF to newly developed fat cells had no effect on lipolysis but, at higher concentrations, also decreased GPDH activity. These findings suggest that EGF is a potent inhibitor of adipose cell differentiation at physiological concentrations, and may be involved in the control of human adipose tissue development and function.     

Inhibition of the activation of Hageman factor (factor XII) by platelet factor 4

Platelet factor 4 is a polypeptide constituent of platelet alpha granules that is released during platelet aggregation and inhibits heparin-mediated reactions. Hageman factor (factor XII) is a plasma proenzyme that, when activated by certain negatively charged agents, initiates clotting via the intrinsic pathway of thrombin formation. In earlier studies using crude systems, platelet factor 4 inhibited activation of Hageman factor by dextran sulfate or cerebrosides, but not activation of Hageman factor by kaolin or ellagic acid. In the present study we examined the mechanisms of inhibition by platelet factor 4, using purified reagents. Platelet factor 4 inhibited activation of Hageman factor by ellagic acid, as measured by amidolysis of a synthetic substrate of activated Hageman factor, an effect inhibited by heparin or by an anti-platelet factor 4 antiserum. Coating glass tubes with platelet factor 4 before addition of normal plasma significantly lengthened the partial thromboplastin time of normal plasma. In addition, the clot-promoting properties of kaolin were inhibited by its prior exposure to platelet factor 4. Thus, the inhibitory properties of platelet factor 4 directed against the activation of Hageman factor were confirmed in a purified system. In this purified system, in contrast to earlier studies using crude systems, platelet factor 4 inhibited activation of Hageman factor by glass, ellagic acid, or kaolin.