Biomedical subjects

M Menger

Publications and source records attributed to M Menger.

24 records · Page 2Linked to original sources

PubMed1987

A cobra venom factor (CVF)-induced C3 convertase activity in the hemolymph of Galleria mellonella.

A cobra venom factor (CVF)-induced C3 convertase has been generated from the hemolymph of Galleria mellonella. CVF was immobilized on Sepharose 4B and treated with cell-free hemolymph obtained from either unvaccinated G. mellonella larvae or larvae immunized with formalized Pseudomonas aeruginosa. The C3-cleaving activity was detected by the ability to cleave the alpha-chain of bovine C3 in a manner analogous to the CVF-induced mammalian C3 convertase, CVF,Bb. The insect-derived C3 convertase formed at 28 degrees C but not at 37 degrees C, then once formed was active at both 28 degrees C and 37 degrees C. EDTA did not inhibit the formation and action of the insect derived C3 cleaving activity.

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PubMed1987

Arachidonic acid lipoxygenase pathways and increased vascular permeability in isolated rabbit lungs.

Products of arachidonic acid (AA) pathways have repeatedly been implicated in acute lung vascular injury with respiratory distress. In blood-free perfused isolated rabbit lungs, AA endogenously released or exogenously applied causes an acute pressor response, mediated by metabolites of the cyclooxygenase pathway including thromboxane A2. Moreover, bolus application of AA (final concentration, 100 microM in the recirculating buffer) during an acute hydrostatic challenge was recently noted to cause a rapid, severalfold increase in the capillary filtration coefficient (Kf,c), though any significant rise in pulmonary vascular pressure was inhibited by indomethacin. In the present study, we showed that during this mode of AA bolus application in cell-free perfused rabbit lungs, microgram amounts of peptidoleukotrienes (LTE4 greater than LTC4 greater than LTD4) and LTB4 were released into the recirculating buffer within 5 min and continued to be released even after 2 exchanges of the perfusion fluid. In the presence of 2 structurally unrelated lipoxygenase inhibitors (nordihydroguaiaretic acid and AA-861), the leukotriene release was nearly completely inhibited and the AA-induced severe increase in vascular permeability was significantly reduced (2.5- to 3-fold rise in Kf,c, compared to a greater than 10-fold increase in Kf,c in the absence of lipoxygenase inhibition). Exogenous LTC4 caused a dose-dependent, sustained pressure rise in protein-free perfused lungs, apparently mediated via the pulmonary generation of AA cyclooxygenase products. Bolus application of 10 micrograms LTC4 or LTD4 or 7.5 micrograms LTB4 in protein-free perfused lungs during an acute hydrostatic challenge did not, however, mimic the AA bolus-induced severalfold increase in vascular permeability.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1986

Increased lung vascular permeability after arachidonic acid and hydrostatic challenge.

Arachidonic acid (AA) metabolites are known to be potent vasoactive substances in the pulmonary circulation, whereas their influence on lung vascular permeability is still uncertain. We investigated the effect of AA bolus injection on the capillary filtration coefficient (Kf,C) of isolated rabbit lungs, recirculatingly perfused with Krebs-Henseleit albumin (1%) buffer. Kf,C was measured using repetitive sudden venous pressure elevations (7.5 Torr) and time zero extrapolation of the slope of the weight gain curve. It ranged from 1.3 to 2.4 cm3 X s-1 X Torr-1 X g-1 X 10(-4) in control lungs. Pulmonary arterial injection of AA (100 microM; in presence of 20 microM indomethacin to suppress pulmonary arterial pressure rise) during an acute hydrostatic challenge, but not at zero venous pressure, caused a greater than 10-fold increase in Kf,C. Vascular compliance was not altered. Additional experiments, performed under zero-flow conditions to avoid any ambiguity in microvascular pressure, corroborated the severalfold increase in vascular permeability, detectable within 3 min after AA application during acute hydrostatic challenge.

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PubMed1985

Isolation and characterization of the third component of bovine complement.

C3 was obtained from bovine serum by polyethylene glycol precipitation and chromatography on DEAE-Sephadex A-50, CM-Sephadex A-50 and Sephacryl S-200. The protein has a molecular weight of 183,000 (alpha-chain 114,000 and beta-chain 69,000). A CVF-induced bovine C3 convertase (Sepharose-CVF.Bb) cleaved C3 into C3a (11,000) and C3b (172,000) as shown by SDS-polyacrylamide gel electrophoresis. Isoelectricfocusing of C3 demonstrated at least three electrophoretic variants with pI 6.55-6.85. The isolated protein promoted the formation and action of a C3 convertase in the presence of purified bovine factors B and D. A monospecific antiserum prepared in rabbits failed to cross react with human C3 or CVF. C3c was identified as a contaminant during the isolation of C3.

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PubMed1984

Alternative pathway of bovine complement: concentration of factor B, hemolytic activity and heritability.

Concentrations of bovine factor B (Bbov) were determined by radial immunodiffusion in sera of 46 Holstein cows and heifers aged one to nine years. Mean values were 34.2 +/- 5.3 mg/100 ml. A hemolytic diffusion plate assay in agarose gel in presence of 10 mM EGTA and 5 mM Mg accurately measured concentrations of purified Bbov but gave higher mean values, i.e. 47.8 +/- 10.2 mg/100 ml, for concentrations of Bbov in whole sera. Hemolytic values obtained by the hemolytic diffusion plate assay, however, weakly correlated (r = .4539, p less than 0.01) with the serum concentration of Bbov measured by radial immunodiffusion. It was concluded that the hemolytic diffusion plate assay was not an accurate technique for the quantitative measurement of Bbov but a good assay for quantitation of the total hemolytic activity mediated via activation of the alternative complement pathway. It is suggested that the difference between the values obtained by the two tests for one particular serum is, to some degree, an expression of the ratio of amplification and restriction of the alternative pathway activity. No significant heritability (offspring and one parent) was detected for the hemolytic activity of serum. A heritability of 0.93 at a significance level of p less than 0.1 was determined for the serum concentration of Bbov.

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PubMed1984

Factor D of the alternative pathway of bovine complement: isolation and characterization.

Factor D of the bovine alternative complement pathway has been purified by chromatography on CM-Sephadex C-50, Sephacryl S-200 and hydroxylapatite. The isolated factor D (0.25 mg from 1 litre of bovine serum) had an apparent molecular weight of 27,500 and a pI of 7.2. In whole bovine serum the pI of factor D was also 7.2. The isolated protein caused the Mg++-dependent cleavage of bovine factor B in the presence of cobra venom factor (CVF) to generate a haemolytically active C3-convertase as shown by SDS-polyacrylamide gel electrophoresis and haemolytic diffusion plate assays. Bovine factor D and human factor D were interchangeable in restoring the alternative pathway haemolytic activities of both bovine RD and human RD (factor D deficient sera). The haemolytic activity of bovine serum factor D was completely inhibited by 20 mM diisopropylfluorophosphate (DFP) but only 25% inhibited by 1 mM DFP. Serum heated at 56 degrees C for 10 min completely lost factor D activity but purified factor D was relatively more heat stable.

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