Exposure significance

Fed PCB 133 at 550 mg/kg diet FW or PCB 197 at 530 mg/kg diet FW for 65 days, followed by a clean diet for 89 days, then reexposure to the contaminated diet for another 37 days No PCB clearance during initial exposure significant elimination of both PCBs when fed a clean diet. During reexposure, uptake efficiency for both PCBs was significantly higher than during the initial exposure 8... 

Gy, single exposure Significantly decreased response rate over the first 4 weeks performance normal during weeks 5-6 9% reduction in body weight 45... 

Similarly, except for what are likely secondary effects following acute lethal exposures, significant cardiovascular injury has not accompanied hepato/renotoxic inhalation exposure to carbon tetrachloride in a variety of experimental animals (Adams et al. 1952 Prendergast et al. 1967 ... 

Decreased oxygen production immediately on exposure significant recovery within 2 weeks despite constant atrazine concentrations (Cunningham etal. 1984)... 

In another case-control study in Brazil, congenital anomalies were compared in 34 misoprostol-exposed children and 4639 unexposed controls (35). Misoprostol exposure significantly increased the risk of arthrogryposis (OR = 8.5 95% Cl = 2, 37), hydrocephalus... 

Fig. 3. (A) SK-N-SH neuronal cells were cotransfected with Bcl-xL or Bcl-xL AkB luciferase reporter plasmids together with pSG-c-Rel and pSG-RelA, or a combination ofpSG-p50, pSG-RelA, andpSG-c-Rel expression plasmids. Control cells were transfected with empty pSG5 vector. Twenty-four hours later the luciferase activity was measured. Mutation of NF- B binding site blocked the luciferase expression. The c-Rel-containing dimers, p50/c-Rel and RelA/c-Rel, but not p50/RelA complex, were able to activate Bcl-xL promoter. Values are mean S.E.M. of three experiments run in triplicate ( /> < 0.05 vs. the corresponding control value). (B) OGD-induced NF-acB activation promotes Bim but not Bcl-xL transcription. Primary cortical neurons were transfected with Bim or Bcl-xL luciferase reporter plasmid or with Bim and Bcl-xL AkB luciferase reporter plasmids and then exposed to OGD. Four hours later, luciferase activity was measured. The OGD exposure significantly induced Bim and decreased Bcl-xL promoter activity. Mutation of NF-kB binding sites reduced the luciferase expression. Values are mean S.E.M. of three experiments run in triplicate p < 0.05 vs. the corresponding control value p < 0.05 vs. corresponding wild-type luciferase reporter plasmid). For methods and details, see Samico et al. (2009).

Benzene, administered intraperitoneally at 600 mg/kg in com oil, 2 times per day for 2 days to male C57BL/6J mice, caused a significant depression in the total number of nucleated bone marrow cells per femur, when measured on day 3 (Niculescu and Kalf 1995). Additional experiments with 7-day exposure revealed that there was an initial depression in erythroid cells on day 3 which remained constant lymphocytes exhibited a progressively depressive effect, and the numbers of intermediate and terminally differentiated granulocytes exhibited a progressive increase over the 7 days of exposure. Upon cessation of the benzene treatment, the bone marrow appeared to begin recovery, with the number of nucleated cells equal to control animals by day 7 after treatment ended. Concomitant administration of IL-la prevented the decrease in nucleated bone marrow cells, whereas IL-la administered after 2 days of benzene exposure significantly increased the rate of recovery of bone marrow cellularity. 

In another case-control study in Brazil, congenital anomalies were compared in 34 misoprostol-exposed children and 4639 unexposed controls (29). Misoprostol exposure significantly increased the risk of arthrogryposis (OR = 8.5 95% Cl = 2, 37), hydrocephalus (OR = 4.2 Cl = 1.5, 12), terminal transverse limb reduction (OR = 12 Cl = 3.5, 41), and limb constriction ring or skin scars (OR = 40 Cl = 11, 153). There were 13 different defects not previously described in the misoprostol-exposed cases, but only holoprosencephaly and bladder exstrophy significantly exceeded the expected number. 

Acute and subacute toxicity studies conducted in Charles Foster rats showed that MIC exposure significantly inhibits weight gain in a dose-dependent manner. These rats showed pathological lesions in the viscera, bronchial tree, lungs, liver, and kidneys. In another study, F344 rats exposed to 3 ppm MIC for 6 h day for 4 days showed significant mortality within 28 days. 

Radon in houses can come from building materials, the soil under the house, the water, and the domestic gas. Some materials such as alum shale and phospho-gypsum have significantly higher radium concentrations than others and can thus cause increased internal radon concentrations to increase. Ventilation rates in basements and in houses in general can reduce exposure significantly. 

N-acetyl cysteine (NAC) in animal studies, NAC administered intratracheally 45-60 min after high-dose phosgene exposure significantly reduced development of pulmonary edema (15,34). The appropriate dose for humans would be 20 mL of a 20% NAC solution administered via nebulizer. However, there is no evidence for using this regimen in humans, and the FDA has not approved its use for prophylactic treaunent of phosgene exposure (34). 

Exposure of NK cells to DMPTC for 1 h caused no significant decreases in cytotoxic function at any concentration (1-10 pM) (Table 4.5.5). However, a 24 h exposure to 10 pM DMPTC caused a 98% decrease in the capacity of NK cells to lyse tumor cells and 2.5 pM DMPTC for 24 h decreased NK lytic function by 52%. A 48 h exposure significantly decreased the ability of NK cells to lyse tumor cells at concentrations as low as 1 pM (45%) and a 6 d exposure to 1 pM decreased lytic function by 84% (Table 4.5.5). ... 

---