Enhancement Of Hemolysis Research Articles

Partial characteristics of hemolytic factors secreted from airborne Aspergillus and Penicillium, and an enhancement of hemolysis by Aspergillus micronesiensis CAMP-like factor via Staphylococcus aureus-sphingomyelinase.

One of the advantages for initial survival of inhaled fungal spores in the respiratory tract is the ability for iron acquisition via hemolytic factor-production. To examine the ability of indoor Aspergillus and Penicillium affecting hemolysis, the secreted factors during the growth of thirteen strains from eight species were characterized in vitro for their hemolytic activity (HA) and CAMP-like reaction. The hemolytic index of HA on human blood agar of Aspergillus micronesiensis, Aspergillus wentii, Aspergillus westerdijkiae, Penicillium citrinum, Penicillium copticola, Penicillium paxilli, Penicillium steckii, and Penicillium sumatrense were 1.72 ± 0.34, 1.61 ± 0.41, 1.69 ± 0.16, 1.58 ± 0.46, 3.10 ± 0.51, 1.22 ± 0.19, 2.55 ± 0.22, and 1.90 ± 0.14, respectively. The secreted factors of an Aspergillus wentii showed high HA when grown in undernourished broth at 25°C at an exponential phase and were heat sensitive. Its secreted proteins have an estimated relative molecular weight over 50 kDa. Whereas, the factors of Penicillium steckii were secreted in a similar condition at a late exponential phase but showed low HA and heat tolerance. In a CAMP-like test with sheep blood, the synergistic hemolytic reactions between most tested mold strains and Staphylococcus aureus were identified. Moreover, the enhancement of α-hemolysis of Staphylococcus aureus could occur through the interaction of Staphylococcus aureus-sphingomyelinase and CAMP-like factors secreted from Aspergillus micronesiensis. Further studies on the characterization of purified hemolytic- and CAMP-like-factors secreted from Aspergillus wentii and Aspergillus micronesiensis may lead to more understanding of their involvement of hemolysis and cytolysis for fungal survival prior to pathogenesis.

Oligomeric behavior of Bordetella pertussis adenylate cyclase toxin in solution

Adenylate cyclase (AC) toxin from Bordetella pertussis inserts into eukaryotic cells, producing intracellular cAMP, as well as hemolysis and cytotoxicity. Concentration dependence of hemolysis suggests oligomers as the functional unit and inactive deletion mutants permit partial restoration of intoxication and/or hemolysis, when added in pairs [M. Iwaki, A. Ullmann, P. Sebo, Mol. Microbiol. 17 (1995) 1015–1024], suggesting dimerization/oligomerization. Using affinity co-precipitation and fluorescence resonance energy transfer (FRET), we demonstrate specific self-association of AC toxin molecules in solution. Flag-tagged AC toxin mixed with biotinylated-AC toxin, followed by streptavidin beads, yields both forms of the toxin. FRET measurements of toxin, labeled with different fluorophores, demonstrate association in solution, requiring post-translational acylation, but not calcium. AC toxin mixed with ΔR, an inactive mutant, results in enhancement of hemolysis over that with wild type alone, suggesting that oligomers are functional. Dimers and perhaps higher molecular mass forms of AC toxin occur in solution in a manner that is relevant to toxin action.

The Effects of Humic Acid–Arsenate Complexes on Human Red Blood Cells

Humic acid (HA) has been proposed as factor in the cause of Blackfoot disease (BFD) among individuals who live along the southwest coast of Taiwan. In this study, the interaction of the synthetic humic acid, made from catechol, with sodium arsenate (As(V)) was investigated and assessed with respect to damage to human red blood cells. HA is characterized as phenolic and phenolic carboxylic polymer structures containing both -COOH and -OH as their main functional groups. HA and As(V) alone are able to hemolyze 60–100 and 5–20% human red blood cells at concentrations of 50–300 μg/ml and 5–100 mM, respectively, after 6 h. HA is shown to be relatively ineffective in causing ATP depletion of red blood cells. For organometallic complexes composed of HA–As(V) the inhibition effect of EDTA was completely abolished and the use of the triple complex HA–As(V)–EDTA resulted in an enhancement of hemolysis. HA caused lipid peroxidation in a concentration- and time-dependent manner. However, HA–As(V) and As(V) decreased lipid peroxidation. These results indicated that HA initiates oxidative stress on red blood cells and this results in their dysfunction. HA-chelated high-concentration metal complexes inhibited the structures containing the main functional groups involved in decreasing hemolysis, and, thus, HA may be a significant factor in the etiology of BFD.

Binding of vitronectin and clusterin by coagulase-negative staphylococci interfering with complement function.

Coagulase-negative staphylococci (CoNS) are commonly associated with infections of prosthetic devices mediated by adsorbed host factors on biomaterial surfaces. Complement activation is known to occur and induce unspecific inflammation around the biomaterials. Human vitronectin (Vn) and clusterin (Clu), two potent inhibitors of complement, can be bound by CoNS. With a hypothesis whether binding of Vn or Clu influences complement activation, two measurements were determined. For Vn, complement activation was measured with a mouse anti-activated human C9 antibody. In the presence of Vn-binding strain, Staphylococcus hemolyticus SM13I, complement activation on a surface pre-coated with Vn occurred as it did in the absence of Vn pre-coating. For S. epidermidis 3380, which does not express binding of Vn, complement activation on a Vn-presented surface was significantly decreased. For Clu, erythrocytes lysis was measured to reflect the end product of complement activation (membrane attack complex). The complement-induced hemolysis increased when human serum was pre-incubated with Clu-binding strains, S. epidermidis J9P. The enhancement of hemolysis by J9P decreased when serum was supplemented by exogenous Clu. The data imply that interaction between CoNS and Vn or Clu interferes with one of their physiological functions, complement inhibition.

Hemolytic activity and siderophore production in different Aeromonas species isolated from fish.

The hemolytic activity and siderophore production of several strains of motile aeromonads were determined. The hemolytic activity of Aeromonas caviae and Aeromonas eucrenophila was enhanced after trypsinization of the samples. The enhancement of hemolysis was observed in strains that carried an aerolysin-like gene, detected by a PCR procedure. Siderophore production was demonstrated in all but one strain of Aeromonas jandaei. No apparent relationship was observed between the presence of plasmid DNA and hemolysis or siderophore production.

Combined effect of dextrose and sodium chloride on red cell osmotic fragility.

AbstractObservations indicating an enhancing effect of sodium on hemolysis of red cells suspended in dextrose solution prompted study of the mechanism of this effect. Osmotic fragility of red cells from normal subjects and from patients was measured in 5% dextrose solution (5D/W), 5% dextrose combined with various concentrations of sodium chloride (5D/NaCl), lithium chloride, and potassium chloride. The influence of ouabain on osmotic hemolysis in 5D/ NaCl was also studied, and the glucose content of ghost red cells was determined when incubated in 5% dextrose with 0.05% NaCl (5D/O.05NaCl), as compared with 5D/W.In the presence of minimal amounts of NaCl (0.05%) at pH 4.8, average hemolysis was greater than in the absence of NaCl, ie, 39% vs 24% in normal subjects (P < 0.02) and 40% vs 31% in a group of unselected patients (P < 0.05). When the pH was adjusted to 7.4 in the patient group, the results were 34% vs 21% (P < 0.05). The sodium‐induced enhancement of hemolysis in dextrose solution was virtually duplicated when LiCl and KCl were substituted for NaCl (P < 0.01 and < 0.05, respectively). On the other hand, in the presence of ouabain, the sodium‐induced enhancement of hemolysis was abolished. The overall glucose content of ghost red cells incubated in 5D/0.05NaCl was 53% greater than in 5D/W (P < 0.005), whereas with ghost red cells depleted of adenosine triphosphate (ATP), it was only 32% greater (P < 0.01).These results suggest that glucose transport across the red cell membrane is enhanced by the sodium ion, presumably by triggering the membrane sodium‐potassium ATPase system.