Complement binding to erythrocytes is associated with macrophage activation and reduced haemoglobin in Plasmodium falciparum malaria.

We have examined IgG and complement factor C3d deposition on erythrocytes by means of the direct Coombs' test (DAT) and looked for an association with the anaemia seen in falciparum malaria in children living in an area of hyperendemic malaria transmission (in Ghana). In one study (in 1997), 53 out of 199 patients had a positive DAT. Of these, 45 samples reacted with anti-C3d antibodies, 2 with anti-IgG and 6 with both reagents. There were significantly lower haemoglobin (Hb)-levels and higher prevalence of spleen enlargement in DAT-positive than in DAT-negative patients. Hb-levels were independently associated with DAT and age. This initial study was designed to investigate the role of intravascular haemolysis (IVH), but we found no association between IVH and either DAT result or anaemia. Because of the risk of selection bias we repeated the study using consecutive enrollment of malaria patients and were able to confirm the results in a total of 49 DAT-positive and 183 DAT-negative patients. This second study (in 1998) was designed to look at the importance of erythrophagocytosis through measurement of plasma neopterin levels and total nitrite and nitrate as markers of NO-release. Both parameters were significantly higher in DAT-positive than in DAT-negative patients (P < 0.001), indicating that complement binding to erythrocytes was associated with macrophage activation. Plasma levels of haptoglobin, interleukin-10 and tumour necrosis factor-alpha did not vary between the groups. The studies support the role of complement activation and erythrophagocytosis in the pathogenesis of anaemia in falciparum malaria in African children.     

Lindholm blood coagulation test values of some glow-discharge polymer surfaces.

An ultrathin layer (approximately 500A) of glow-discharge polymer that is strongly bonded to a polymer film substrate can be sued to modify the blood compatibility of the polymer surface. Glow-discharge polymers of tetrafluoroethylene, hexamethyldisiloxane, ethylene-N2, and allene-N2-H20 were deposited onto Mylar film and subjected to Lindholm whole blood coagulation tests. Lindholm tests were performed in a manner that permitted statistical analysis. This was done by repeating the preparation of samples as well as the coagulation tests a number of times. Results showed that Lindholm tests values were useful in obtaining information pertinent to compatibility of surfaces with fresh human blood and to reproducibility of sample preparation by glow-discharge polymerization. The study also revealed that glow-discharge polymerization is a promising method to impart blood compatibility without altering other bulk properties of substrate polymers.     

The estimation of dose equivalent from the activation of plastic scintillators

It is shown that the dose equivalent to be attributed to the fluence measured by the activation of 11C in a plastic scintillator when exposed outside the shielding of a high-energy proton accelerator is close to the value of 28 fSv m2 in current use at the European Organization for Nuclear Research (CERN) when the neutron component of the field alone is considered. However the presence of significant numbers of pions and protons in stray fields would raise this conversion factor to approx. 45 fSv m2.     

The effect of malnutrition on insulin binding to rat erythrocytes.

Insulin binding to erythrocyte receptors was compared in malnourished and control rats. Percentage specific insulin binding to malnourished rat erythrocytes was significantly lower than to control erythrocytes (P less than 0.001). The low insulin binding in the malnourished rat erythrocytes was accompanied by low insulin receptor affinity (P = 0.035).     

Heinz bodies formed in erythrocytes by fatty acid ozonides and ozone.

Ozonides of the methyl esters of oleic, linoleic, linolenic and arachidonic acids were found to produce Heinz body inclusions in human and mouse erythrocytes. No simple relationships between structure and activity were noted. Concomitant with Heinz body formation, methemoglobin and loss of cellular thiols were observed. Methyl ozonides readily oxidized glutathione and 1 mole of oxidized glutathione was formed per mole of methyl oleate ozonide. Methyl ozonides catalyzed the formation of disulfide-linked interchain polymers between hemoglobin and ovalbumin. Heinz bodies were not produced with ozone in the absence of unsaturated lipids. Heinz bodies were observed in the blood of mice exposed to ozone (0.85 ppm) for 48 hours. These observations suggest that fatty acid ozonides could serve as a toxic chemical species formed on ozone inhalation and could explain the divergent protective effects of lipid antioxidants and thiol generating systems in vivo.     

Separation of Plasmodium berghei-parasitized rat erythrocytes by means of carrier-free electrophoresis.

A carrier-free electrophoresis apparatus was used to isolate rat erythrocytes parasitized with Plasmodium berghei. The region of high electrophoretic mobility yielded noninfected erythrocytes, whereas that of low electrophoretic mobility yielded erythrocytes infected with viable parasites. Over 98% purity of parasitized erythrocytes was obtained when blood at an advanced stage of parasitaemia was used. Merozoite-rich fractions were also observed. This continuous one-step separation method should provide large numbers of parasitized erythrocytes for use in immunological and biochemical studies of malaria.     

Attempts to control clothes-borne infection in a burn unit, 3. An open-roofed plastic isolator or plastic aprons to prevent contact transfer of bacteria.

An open-roofed plastic isolator was built in a single patient isolation room in a burn unit. It was designed to prevent contact contamination only, as this had been shown to be the important route of cross-colonization in the unit. To exclude any possible effect on airborne transfer of bacteria, the isolator was first examined by means of an airborne particle tracer of the same size as bacteria-carrying particles. Such experiments indicated that the isolator might prevent some transfer out of but not into the isolator. This was not confirmed in simulated nursing experiments nor in a patient study, where the air counts of bacteria were practically the same inside and outside the isolator wall. Two patients only were nursed in the isolator. Both patients acquired exogenous colonizations from other patients, one with Ps. aeruginosa and the other with S. aureus. Nursing in the isolator was difficult and staff-demanding. In simulated nursing experiments, plastic aprons and gauntlets as the only protective measures against contact contamination gave as much protection to a mock patient as did the isolator. S. aureus were released from nurses' clothes more easily during work with the isolator than in open nursing with aprons and gauntlets. In conclusion, the isolator did not seem to be a realistic alternative to impermeable clothes such as plastic aprons as a means of preventing clothes-borne cross-contamination between burn patients.     

Antibody-independent complement activation by cardroom cotton dust.

The in vitro activities of cardroom cotton dust (before treatment, BCD) and treated cotton dust (TCD) on the human complement cascade were examined. While both dusts consumed hemolytic complement and reduced C3, quantifiable differences were observed. Untreated BCD was much more active than was TCD. Complement was activated via the alternative pathway, and although endotoxin was 58 times greater in BCD than TCD, the endotoxin content of BCD could not account for the total complement consumed. Activation of the complement cascade in vivo may provide one mechanism to account for the symptoms experienced by byssinotic subjects after exposure to cotton dust.     

Concentration and separation of erythrocytes infected with Plasmodium falciparum by gradient centrifugation.

Concentration of infected erythrocytes was achieved in cell suspensions derived from long-term culture of Plasmodium falciparum growing asynchronously in human erythrocytes. This new procedure involves the slow centrifugation (at 33 g) of erythrocyte suspensions through 5% Ficoll solutions. Mature asexual erythrocytic forms are preferentially retained in the gradient solution (top fraction). After further gradient centrifugation of these parasitized cells, the concentration of mature forms is increased 15- to 31-fold and a mature form parasitaemia of 71-81% is obtained in the final erythrocyte suspension. Furthermore, at least 75% of the total number of the mature forms can be retrieved by this method. Parasitized cells that are not retained in the gradient are sedimented to the bottom of the tube (bottom fraction) and consist predominantly of ring forms. Parasites from both the top and bottom fractions are viable and have been used to initiate short-term synchronous cultures. By providing purified parasite preparations, this simple procedure will facilitate immunological, chemotherapeutic, and biochemical studies with P. falciparum.     

Soft plastic bread packaging: lead content and reuse by families.

The presence of lead in labels painted on soft plastic bread packaging was evaluated. Lead was detected on the outside of 17 of 18 soft plastic bread bags that were analyzed, with an average of 26 +/- 6 mg per bag with lead. Of 106 families questioned, 16 percent of respondents reported turning the bags inside out before reusing for food storage, thus putting food in contact with the lead paint. We estimate that a weak acid, such as vinegar, could readily leach 100 micrograms of lead from a painted plastic bag within 10 minutes. Further, lead and other metals painted on food packaging of any type becomes part of the municipal waste stream subject to incineration and to land-filling. The use of lead in packaging presents an unnecessary risk to public health.     

Changes induced by exposure of the human lung to glass fiber-reinforced plastic

The inhalation of glass dusts mixed in resin, generally known as glass fiber-reinforced plastic (GRP), represents a little-studied occupational hazard. The few studies performed have highlighted nonspecific lung disorders in animals and in humans. In the present study we evaluated the alteration of the respiratory system and the pathogenic mechanisms causing the changes in a group of working men employed in different GRP processing operations and exposed to production dusts. The study was conducted on a sample of 29 male subjects whose mean age was 37 years and mean length of service 11 years. All of the subjects were submitted to a clinical check-up, basic tests, and bronchoalveolar lavage (BAL); microscopic studies and biochemical analysis were performed on the BAL fluid. Tests of respiratory function showed a large number of obstructive syndromes; scanning electron microscopy highlighted qualitative and quantitative alterations of the alveolar macrophages; and transmission electron microscopy revealed the presence of electron-dense cytoplasmatic inclusions indicating intense and active phlogosis (external inflammation). Biochemical analyses highlighted an increase in protein content associated with alterations of the lung oxidant/antioxidant homeostasis. Inhalation of GRP, independent of environmental concentration, causes alterations of the cellular and humoral components of pulmonary interstitium; these alterations are identified microscopically as acute alveolitis.