Lead and growth status of school children living in the copper basin of south-western Poland: differential effects on bone growth.

OBJECTIVE: The study analyzed the relationship between blood lead (BPb) levels and growth status of upper and lower body segments among schoolchildren living in the copper basin of south-western Poland. MATERIALS AND METHODS: Schoolchildren 7-15 years of age (463 males, 436 females) living in the vicinity of copper smelters and refineries were tested for blood lead. Weight, height, symphyseal height (leg, lower segment length), and arm length were measured. Trunk (upper segment including head and neck) length was estimated as height minus symphyseal height. The BMI was calculated using weight/height2 (kg m-2). RESULTS: Mean blood lead in the total sample was 7.7 +/- 3.5 micro g dL-1 (2.0-33.9 micro g dL-1). Blood lead level was significantly and linearly related to reduced weight, height, trunk, leg, and arm lengths. The estimated reduction in height was 5 mm per 1 micro g dL-1 increase in blood lead (5.0 cm per 10 micro g dL-1). The reduction occurred in leg length (males, 64%; females 72%) compared to trunk length (males, 36%; females, 28%). Estimated reductions in arm length were 2.0 cm (males) and 2.5 cm (females) per 10 micro g dL-1 increase in blood lead. Hence, limb (leg and arm) lengths were markedly reduced. CONCLUSIONS: Linear skeletal growth was reduced with increased blood lead, even at levels below that considered for action by US CDC standards. The reduction in height occurred primarily in leg length. Arm length was also reduced, suggesting limb lengths in general were affected by blood lead. Results are consistent with lead-associated interruption of (1) major epiphyseal growth plate chondrocyte hyperplasia, hypertrophy, and interrupted matrix calcification as a primary cause of stunted long bone growth, and reduced stature; and (2) attenuated osteoblast activity (proliferation and migration) as a secondary cause of stunted growth in the study population.

Effect of DNA bending in various regions of a consensus-like Escherichia coli promoter on its strength in vivo and structure of the open complex in vitro.

A series of E. coli promoters made of the consensus -35 and -10 hexamers separated by 17 bp spacer with variously located bending dTn.dAn, n = 5 or 6, sequences was constructed and cloned into the plasmid pDS3. Electrophoretic gel mobilities of restriction fragments containing these promoters correlated with the number of the T tracts encoded in the promoter sequences. The open complexes formed by E. coli RNA polymerase on promoters containing the T5(-34...-38) tract exhibited gel retardation indicative of their different gross geometry. The strength of these promoters measured in vivo in relation to an internal transcriptional standard was shown to be significantly lower than that of the group without the T5(-34...-38) tract. Within both these groups the promoters with two T6 tracts in the spacer, aligned in phase with the B-DNA helix repeat, had lower transcriptional activity, while the T6 tract encoded in the -7...-2 promoter region apparently had no influence on the strength of the respective promoters.