[Free radicals in silicosis]. / Radicali liberi în silicoza.

The prolonged inhalation of silicon powders induces an oxidative stress at respiratory system level, due to the formation of free radicals (FR). Free radical origin is either exogenous (as a result of the chemical structure of powders) or endogenous (result of the endocytosis of silicon powders). Bivalent Fe ions are implied in FR generation, and the substances with Fe chelating and antioxidizing actions block the evolution of silicosis.

[The effect of smoking on immunological parameters in silicosis]. / Influenta fumatului asupra unor parametri imunologici în silicoza.

The paper reports on the smoking influence on some immunologic parameters in a group of patients with micronodular silicosis. 3 groups of subjects were studied: I--group with micronodular silicosis, smokers with cigarette index 300; II--group with micronodular silicosis, nonsmokers; III--control group. The following immunologic parameters were determined: 1. Test of blastic transformation of LT at PHA and PHA+IL-1 TTB; 2. Inhibition of leukocyte migration--indirect test; 3. Phagocytosis test of sheep erythrocytes. The results obtained show, in the patients with silicosis, suppression of the ability of blastic transformation, of lymphokines release and non-efficient phagocytosis. Improvement of the lymphocyte function by adding IL-1 suggests a deficiency of this monokine in inducing modified immune response in these patients. Smoking depresses more obviously cellular mediated immune response, induced by silicosis.

The in vitro cellular immune response to quartz.

It is known that macrophages release into medium in vitro biologically active substances which modulate immune response. In recent years, increase attention has been directed towards the role of prostaglandin in macrophage function. Guinea pig splenic lymphocytes and peritoneal macrophage cultures were incubated with quartz (DQ12), Corundum and aspirin as prostaglandin inhibitor. Lymphocyte proliferation measured by 3H-thymidine incorporation, and lymphokine release by Bendixen-Soborg capillary test (MIF) were applied. EA rosetting and phagocytosis were determined for macrophage function assessment. Quartz suppressed the immune response evidenced by reduced 3H-thymidine incorporation and decreased lymphokine production. Aspirin (as a specific prostaglandin synthesis inhibitor) restored the affected by quartz immunological parameters. This observation gives support to the hypothesis that the immunological response to quartz involves macrophage prostaglandin release, presumably as a first step of lipid peroxidation.

Effects of selenium on quartz-induced cytotoxicity in macrophages.

Guinea pig peritoneal macrophages were incubated in vitro with various concentrations of selenium (as sodium selenite), quartz, and quartz + selenite. Cellular viability, adhesiveness, migration, and lipid peroxide content as parameters for cytotoxicity were studied. A dose-dependent cytotoxic response of macrophages to selenite was observed. Selenite concentrations of 10(-6), 10(-5), and 10(-4) M were shown to be nontoxic in the various test procedures. Quartz treatment of macrophages reduced cell viability, adhesiveness, and migration, and enhanced lipid peroxide release. Cotreatment of macrophages with nontoxic selenite concentrations suppressed significantly the cytotoxic effects induced by quartz and was effective in reducing the high rate of lipid peroxidation. The results provide support for the role of selenium in the stabilization of macrophage membrane damaged by quartz.

Short-term systems to assess thiophosphoryl chloride standards.

The rat acute oral LD50 value of PSCl3 is 750 mg per kg body weight. A rat 90-day oral feeding study at dose levels of 7.5 mg (P1) and 37.5 mg (P5) per kg resulted in increased body weight gain. Other responses inconsistently varied between dose levels. At 7.5 mg kg-1, a trend towards enhancement of relative weight of liver, spleen, kidney and adrenals was noted; at 37.5 mg kg-1, decreasing relative spleen and adrenal weights were observed. The most of the hematological and biochemical changes in blood serum cannot be believed to be transitory adaptive changes, but valid toxic effects. On the other hand, there are some indicators that suggest a possible trophic effect of this compound. However, the reversible dystrophic changes in liver, as well as the histochemical and histoenzymical results, require us to take into account that inactive chronic hepatitis could be reactivated by further toxic insult. A teratology study demonstrated increased number, body weight and length of fetuses, without apparent pathological events (tumors, external malformations). A mutagenicity test performed on rat femoral bone marrow after 30-days feeding of 37.5 mg kg-1 did not indicate any significant change in the incidence of chromosomal aberrations, compared with the control group. The recommended maximum allowable concentration in the working zone for thiophosphoryl chloride in air was set at 3 mg m-3.

Migration inhibition tests in penicillin allergy.

The lymphocyte blastic transformation (TTB), leucocyte and macrophage inhibition tests has been compared in 18 hypersensitive to penicillin patients and in 15 patients with hypersensitivity to PPD. It has been shown that TTB was positive in all penicillin allergy cases, due to the constantly LT sensitization, and therefore this test constitutes an efficient method for the in vitro diagnosis of penicillin hypersensitivity. Macrophage inhibitory factor (MIF) was absent in all penicillin allergic subjects. Leucocyte migration inhibition test was positive only when gamma globulin coupled penicillin was used or in the presence of autologous plasma pretreated penicillin. This suggests that leucocyte migration inhibition resulted from the specific penicillin antibodies.