The lack of an inhibitory effect of hyaluronate on chondrogenesis in chick limb-bud mesoderm cells grown in culture.

The effect of hyaluronate on chondrogenesis in cultures of chick limb-bud mesoderm cells, derived from stage 20--21, 23--24 and 26 embryos grown at different cell densities and in 3 different culture media, was studied. The results show that hyaluronate at a concentration of 500 microgram/ml, does not consistently produce an inhibition of chondrogenesis in cultures of stage 20--21, 23--24 or 26 limb-bud mesoderm cells in contrast to what has been reported by Toole et al. (1972). It was demonstrated that under optimal conditions, stage 26 cells grown in the absence of hyaluronate do not form as many cartilage colonies in culture as do cells from stage 20--21 or 23--24 embryos. It was determined that culture medium composed of Eagle's MEM supplemented with 7% horse serum, 3% fetal calf serum and 5% 10-day chick embryo extract supported chondrogenesis significantly better than Ham's F-12 supplemented with 10% fetal calf serum. Our results suggest that the inhibition of chondrogenesis by hyaluronate reported earlier is most likely due to the sub-optimal conditions of growth medium, cell density and embryonic stage than to the hyaluronate treatment.

Polycyclic aromatic hydrocarbon exposure in coal liquefaction workers: the value of urinary 1-hydroxypyrene excretion in the development of occupational hygiene control strategies.

Studies in coal liquefaction workers were conducted to examine relationships between work activities, exposure to polycyclic aromatic hydrocarbons (PAHs) and excretion of urinary 1-hydroxypyrene (1-OHP). In a single-week study in operators, the end of work period 1-OHP excretion was an order of magnitude higher than in a shadow control subject, who experienced exposure by inhalation only (shadowed operator = 15.8 mumol mol-1 creatinine; shadow control = 1.07 mumol mol-1 creatinine). Dermal exposure was estimated to account for over 70% of excreted 1-OHP in exposed workers. A second study over 4 consecutive weeks (multi-week study) showed consistency in 1-OHP excretion from week to week both in operators and laboratory technicians, indicating little variation in weekly exposures for these workers. Excretion levels in maintenance workers however, showed some week to week variation, consistent with the variable nature of exposures associated with this type of work. A further study involving an end of work period spot assessment for all personnel showed a clear distinction between exposed workers (operators and maintenance staff) and other workers not thought to be exposed (laboratory technicians and office staff). Findings in the course of these studies indicated that there is no loss of 1-OHP at 4 degrees C, compared with -20 degrees C. On the basis of work to date at the coal liquefaction facility, hygiene control strategies have been proposed involving periodic urinary 1-OHP monitoring.