Experimental measurements of particle retention efficiency of filters used to prevent contamination in respiratory devices.

Objective: Various types of filters have been designed to prevent cross contamination of ventilation and respiratory devices. The aim of this study was to experimentally measure the retention efficiency of four simple filters (antibacterial and antiviral and seven combined filters (antibacterial and antiviral plus heat and water exchangers).

Setting: The respiratory function testing (EFR) central department of a university teaching hospital.

Use of unstable chromosome aberrations for biological dosimetry after the first postirradiation mitosis.

The loss of unstable chromosome aberrations after the first postirradiation mitosis makes their use difficult in radiation dosimetry. We describe here a method which, in a cell population observed at this stage, allows retrospective estimation of the frequencies of the unstable aberrations induced at the time of irradiation, and their use as a dosimeter. The laws controlling the behavior of unstable aberrations during mitosis were defined from a large-scale experiment on irradiated human lymphocytes.

Chromosomal aberrations and DNA repair ability of in vitro irradiated white blood cells of monkeys previously exposed to total body irradiation.

Six monkeys (Macaca fascicularis) were total-body-irradiated with 60Co (fractionated irradiation of 8 or 10 Gy). Blood samples were collected at different times post total-body irradiation, then in vitro irradiated in order to test whether a prior in vivo irradiation could affect the radiosensitivity of their leukocytes. We suggested in a preliminary report that the enhanced chromosomal radiosensitivity of in vivo irradiated monkeys could be correlated with a DNA repair deficiency (Guedeney et al.

Chromosomal aberrations in cynomolgus peripheral lymphocytes during and after fractionated whole-body gamma-irradiation.

Cynomolgus monkeys (Macaca fascicularis) were exposed to fractionated whole-body gamma-irradiation at high and low dose rates for 4 or 5 weeks. The time-dependence of chromosomal aberrations was studied in relation to the number of lymphocytes during irradiation and after exposure for periods of up to about 600 days for chromosomal aberrations and 200 days for lymphocyte counts. Additivity of the daily effects on the number of chromosomal aberrations was observed during the exposures.

Time dependence of chromosomal aberrations induced in human and monkey lymphocytes by acute and fractionated exposure to 60Co.

Changes in the numbers of peripheral lymphocytes with chromosome aberrations were observed in cynomolgus monkeys after fractionated or acute 60Co irradiation at the same total doses. Immediately after irradiation, the yield of dicentrics decreased when the dose was fractionated but remained constant for 20 to 80 days, depending on the dose, when irradiation was acute. Lymphopenia was greater than expected when the dose was fractionated.