Characteristics of titanium dioxide microdispersions with different photo-activity suitable for sunscreen formulations.

The aim of the study was the comparison of photo-activity of three types of titanium dioxide (TiO2) micro-dispersions intended for use as UV filters for cosmetic sunscreen products. The dispersions were also investigated with regard to their influence on the stability of photo-protective systems in cosmetic emulsions, their skin penetration/absorption and their photo-toxicity for humans and skin bacterial flora. All the tested micro-dispersions of rutile TiO2 type (agglomerates with diameter 120-150 nm), with primary particle size lower than 100 nm, demonstrated no phototoxic effect and insignificant antimicrobial behaviour. On the other hand, TiO2 with insufficient deactivation of photo-activity had significant negative impact on the stability of other organic UV filters and therefore on the stability of declared UV protective factors (SPF, UVA-PF). The study demonstrated that the level of deactivation of TiO2 is one of the highly important factors for evaluation of UV filters used as sunscreens.

Switching from zidovudine to didanosine in patients with symptomatic HIV infection and disease progression. ddI Iberian Study Group.

This study evaluated the efficacy of switching to didanosine in patients who were clinically or immunologically progressing despite zidovudine therapy. This multicenter, open-label study involved 400 patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC), who had tolerated zidovudine for at least 12 weeks and had signs of clinical or immunological disease progression. They were randomly assigned to receive 600 mg/d of zidovudine (n=133), 500 mg/d of didanosine (n=131), or 200 mg/d of didanosine (n=136). The primary end point was a new AIDS-defining event or death. The study was prematurely terminated, after the first interim analysis, mainly owing to results of two controlled studies demonstrating that a change to didanosine was associated with an improved outcome in patients with advanced HIV-1 disease. The median duration of follow-up was 53 weeks. The primary end point rates were 41, 58, and 59 (per 100 person-years) in the didanosine 500 mg, didanosine 200 mg, and zidovudine groups (zidovudine vs. didanosine 500 mg, relative risk 1.28, 95% confidence interval, 0.88-1.86, p = 0.19; didanosine 200 vs. 500 mg, relative risk 1.24, 95% confidence interval, 0.85-1.79, p = 0.26). In subjects with a baseline CD4 count of 100/mm3 or more, the primary end point rates were 8, 29, and 25 (per 100 person-years) in the didanosine 500 mg, didanosine 200 mg, and zidovudine groups, respectively (zidovudine vs. didanosine 500 mg, relative risk 2.96, 95% confidence interval 0.91-9.62, p = 0.07). No difference was seen in survival. In the didanosine 500 mg group, more patients had a 50% increase in CD4 cells (10% vs. 1% in zidovudine group, p = 0.01) and an increase of > or = 2.5 kg in body weight (2% versus 3%). Fatal pancreatitis developed in one patient assigned to didanosine 500 mg and in one to zidovudine. Our data suggest that switching from zidovudine to currently recommended doses of didanosine in subjects with ARC or AIDS who show evidence of clinical and laboratory disease progression can be associated with improvements in clinical outcome as well as in surrogate markers of HIV disease progression. This effect tended to be greater among individuals with higher CD4 counts (>100/mm3).

The study of exposure to cadmium in the general population. I. Autopsy studies.

From 1982 to 1986 samples of materials (liver tissue, kidney cortex) were collected from 438 autopsies in Prague. The age of persons was over 50 years and residence time in the area was at least 10 years Concentrations of Cd and Zn were determined in the kidney cortex and the liver tissue using the AAS method. On the basis of the Questionnaire for Relatives, data on smoking habits, and occupational history of the investigated persons were obtained. The results of the study confirmed that the concentration of Cd in analyzed tissues did not exceed values reported in the literature for people of similar age living in Cd uncontaminated areas. In smokers significant increase of Cd in the kidney cortex was found in all age and sex groups. The body burden of Cd in smokers is significantly higher.

Dose-related proximal tubular dysfunction in male rats chronically exposed to lead.

Male Wistar rats were given 0.5 and 2% lead acetate in drinking water for 2 months, 1% lead acetate for 3 months and sodium acetate equimolar to 2% lead acetate for 3 months. Glucose, total proteins, lactate dehydrogenase (LDH), lysozyme and beta 2-microglobulin (beta 2-m) were measured in 24-h urine every month. Kidney weight and histology were also examined. At the three doses, lead exposure produced a significant elevation of the kidney weight. No significant change in urinary parameters was observed in rats given 0.5% lead acetate. Exposure to 1% lead acetate increased the urinary excretion of beta 2-m only. At the 2% lead acetate dose the elevation of beta 2-m excretion was accompanied by an increased urinary output of glucose, total proteins, lysozyme and LDH. Observations of the kidneys by light microscopy were in agreement with these biochemical findings. The nephrotoxic effect of acetate was excluded by the lack of biochemical or histological effects of sodium acetate on the kidney. It is concluded that a proximal tubular dysfunction is induced in rats chronically exposed to high doses of lead.

Synergistic enhancement of the biliary excretion of cadmium by the simultaneous administration of two dithiocarbamates.

The simultaneous i.p. administration of the two chelating agents bis(2-hydroxyethyl)dithiocarbamate (DEDTC) and 4-carboxamidopiperidinedithiocarbamate (INADTC) to rats given cadmium in their drinking water at a level of 50 mg cadmium/liter for 39 days led to a large synergistic effect on the biliary excretion of cadmium. A much smaller synergistic effect on the urinary excretion of cadmium was also noted. When treated with a similar mixture of chelating agents after a similar cadmium-drinking water exposure of 180 days, rats showed significant decreases in both renal and brain cadmium levels.