Early initiation of low-dose aspirin for reduction in preeclampsia risk in high-risk women: a secondary analysis of the MFMU High-Risk Aspirin Study

OBJECTIVE

Early initiation of low-dose aspirin (LDA) may reduce preeclampsia risk. We sought to determine whether LDA was beneficial when initiated <17w0d, within a trial of high-risk women enrolled <26w0d.

STUDY DESIGN

Secondary analysis of the Maternal-Fetal Medicine Units High-Risk Aspirin study, including women enrolled <17w0d, randomized to LDA (60 mg day(-1)) or placebo with chronic hypertension (CHTN, n=186), diabetes (n=191) or prior preeclampsia (n=146). The primary outcome was preeclampsia at any time in pregnancy, secondary outcomes were early preeclampsia (<34w0d), late preeclampsia (⩾34w), small for gestational age (SGA; neonatal birthweight <10th %) and composite (early preeclampsia or SGA). Outcomes were compared by exact Χ(2)-tests.

RESULTS

Baseline characteristics were similar between treatment groups. Aspirin was associated with a lower rate of late-onset preeclampsia ⩾34w (17.36% vs 24.42%, P=0.047), with a 41% reduction in women with CHTN (18.28% vs 31.18%, P=0.041). There were no other significant differences in the outcome.

CONCLUSION

Aspirin initiated <17w0d reduced the risk for late-onset preeclampsia by 29% supporting the practice of early initiation of aspirin in high-risk women.

Autism risk in small- and large-for-gestational-age infants

OBJECTIVE

We sought to determine whether small-for-gestational age (SGA) and large-for-gestational age (LGA) birthweights increase autism risk.

STUDY DESIGN

This was a retrospective cohort analysis comparing children with autism (n = 20,206) within a birth cohort (n = 5,979,605). Stratification by sex and birthweight percentile (SGA, <5th or 5-10th percentile; appropriate size for gestational age [GA], >10th to <90th percentile; LGA, either 90-95th or >95th percentile) preceded Cochran-Mantel-Haenszel analysis for GA effect, and multivariate analysis.

RESULTS

Autism risk was increased in preterm SGA (<5th percentile) infants 23-31 weeks (adjusted odds ratio [aOR], 1.60; 95% confidence interval [CI], 1.09-2.35) and 32-33 weeks (aOR, 1.83; 95% CI, 1.16-2.87), and term LGA (>95th percentile) infants 39-41 weeks (aOR, 1.16; 95% CI, 1.08-1.26), but was decreased in preterm LGA infants 23-31 weeks (aOR, 0.45; 95% CI, 0.21-0.95).

CONCLUSION

SGA was associated with autism in preterm infants, while LGA demonstrated dichotomous risk by GA, with increased risk at term, and decreased risk in the premature infants. These findings likely reflect disparate pathophysiologies, and should influence prenatal counseling, pediatric autism screening, and further autism research.

Ventilation-perfusion inequality in the human lung is not increased following no-decompression-stop hyperbaric exposure

Venous gas bubbles occur in recreational SCUBA divers in the absence of decompression sickness, forming venous gas emboli (VGE) which are trapped within pulmonary circulation and cleared by the lung without overt pathology. We hypothesized that asymptomatic VGE would transiently increase ventilation-perfusion mismatch due to their occlusive effects within the pulmonary circulation. Two sets of healthy volunteers (n = 11, n = 12) were recruited to test this hypothesis with a single recreational ocean dive or a baro-equivalent dry hyperbaric dive. Pulmonary studies (intrabreath V_A/Q (iV/Q), alveolar dead space, and FVC) were conducted at baseline and repeat 1- and 24-h after the exposure. Contrary to our hypothesis V_A/Q mismatch was decreased 1-h post-SCUBA dive (iV/Q slope 0.023 ± 0.008 ml⁻¹ at baseline vs. 0.010 ± 0.005 NS), and was significantly reduced 24-h post-SCUBA dive (0.000 ± 0.005, p < 0.05), with improved V_A/Q homogeneity inversely correlated to dive severity. No changes in V_A/Q mismatch were observed after the chamber dive. Alveolar dead space decreased 24-h post-SCUBA dive (78 ± 10 ml at baseline vs. 56 ± 5, p < 0.05), but not 1-h post dive. FVC rose 1-h post-SCUBA dive (5.01 ± 0.18 l vs. 5.21 ± 0.26, p < 0.05), remained elevated 24-h post SCUBA dive (5.06 ± 0.2, p < 0.05), but was decreased 1-hr after the chamber dive (4.96 ± 0.31 L to 4.87 ± 0.32, p < 0.05). The degree of V_A/Q mismatch in the lung was decreased following recreational ocean dives, and was unchanged following an equivalent air chamber dive, arguing against an impact of VGE on the pulmonary circulation.

Degree of public support for household hazardous waste control alternatives

This paper reports information from Massachusetts on attitudes of householders toward alternative approaches and economic solutions to household hazardous waste (HHW) generation and disposal. Residents appear to be aware of the nature of the HHW problem and clearly support action to address the problem. The majority support a law fining householders for the improper disposal of HHW, endorse paying a sales tax on domestic hazardous products to finance safe disposal, and appear willing to drive up to five miles to dispose of HHW twice yearly.

Household hazardous waste in Massachusetts

Household wastes, when disposed of improperly, are hazardous to health. This paper reports a random digit dial telephone survey of Massachusetts households concerning household hazardous waste (HHW) disposal with a 54% response. Of the automotive oil disposed of by 33% of survey households, 57% was deposited in the ground, sewer, or landfill. Annually by household oil disposal in Massachusetts is estimated to be 8.8 million quarts. Four percent of hazardous waste generated in Massachusetts is from households. Improper disposal makes it a major environmental contaminant. More households (41.5%) in smaller communities disposed of oil compared with 26% of households in larger communities. Paint and pesticides were disposed of by 10% of the households, but were dumped on the ground sewer or landfills more than 90% of the time.

The renal effects of sodium chlorite in the drinking water of C57L/J male mice

The increasing concern over the possibility of adverse health effects due to the chlorination of drinking water has led to a search for alternative methods of disinfection. One potential alternative is chlorine dioxide which, when used, gives rise to the end product chlorite. This study investigated the potential of chlorite as a nephrotoxic agent when administered for various lengths of time (30, 90, and 180 days) in a series of concentrations (4, 20, and 100 ppm as sodium chlorite) to C57L/J male via drinking water. Examination by light and transmission electron microscopes did not reveal any evidence of renal pathologies. In addition, no evidence of significant mortality, water consumption differences, body weight change differences, kidney weight change differences, or differences in the percent kidney to body weight ratio was observed between the various levels of treatments.

Ozone induced hematological changes in mouse strains with differential levels of erythrocyte G-6-PD activity and vitamin E status

A single short term in vivo exposure (6 hr) to O3 (i.e., 0.3, 0.9, 1.5 ppm) markedly affected several hematological parameters in males of two mouse strains (C57L/J and A/J) reared on either a vitamin E normal or deficient diet. Of particular significance is that at the lowest concentration employed (i.e., 0.3 ppm), O3 induced marked decreases in red cell ACHE and increases in heinz body formation and osmotic fragility in both mouse strains regardless of diet type. Although the two mouse strains markedly differ in their RBC G-6-PD activity, they did not consistently differ in responses to O3 exposure.

The effect of in vivo ozone exposure to Dorset sheep, an animal model with low levels of erythrocyte glucose-6-phosphate dehydrogenase activity

Female Dorset sheep were exposed in vivo to ambient ozone levels of 0.12 ppm, 0.25 ppm, 0.50 ppm, 0.70 ppm for 2.75 hours and the effects of this exposure upon erythrocytes were studied. Ozone exposure induced biochemical evidence of oxidant stress as indicated by decreases in GSH levels (at 0.5 and 0.7 ppm ozone) and ACHE (at 0.7 ppm), increases in MetHb (from 0.12 ppm upward) and decreases in red blood cell counts (from 0.12 ppm upward). However, only the decrease in GSH levels at the 0.5 ppm ozone exposure was statistically significant (p = 0.05).

The effect of ascorbic acid on copper-induced oxidative changes in the erythrocytes of rats, sheep, and normal humans

Rats, sheep, and normal humans displayed a comparable sensitivity to copper acetate (3 mM)-induced changes in reduced glutathione (GSH) levels in vitro. However, the human erythrocytes were more sensitive than either animal to methemoglobin (METHB) formation with the rat being least sensitive. Ascorbic acid incubation markedly enhanced the occurrence of copper acetate-induced increases in METHB and decreases in GSH in the sheep and humans. However, ascorbic acid incubation reduced the occurrence of copper acetate-induced increases in METHB, while not effecting changes in GSH in rats.

The effect of ascorbic acid on nitrite-induced methemoglobin formation in rats, sheep, and normal human erythrocytes

Interspecies differences were demonstrated with respect to the occurrence of sodium nitrite-induced methemoglobin (METHB) in the erythrocytes of rats, dorset sheep, and normal humans, with the rats displaying approximately 25-33% of the sensitivity of sheep and human erythrocytes. Ascorbic acid incubation along with the nitrite was able to significantly reduce METHB formation in a dose-dependent manner in both rats and humans but not in sheep.

An evaluation of the dorset sheep as a predictive animal model for the response of G-6-PD deficient human erythrocytes to a proposed systemic toxic ozone intermediate, methyl oleate hydroperoxide

Erythrocytes of both G-6-PD deficient humans and Dorset sheep, an animal model with an erythrocyte G-6-PD deficiency, both responded in a dose dependent manner to the oxidant stress of MOHP as measured by decreases in G-6-PD activity, increases in METHB levels and decreases in GSH. However, the human G-6-PD deficient erythrocytes were considerably more sensitive to the formation of METHB than the sheep erythrocytes while the reverse was the case for the GSH parameter. The results suggest a qualitative difference in the response of sheep erythrocytes and human G-6-PD deficient erythrocytes to MOHP that seriously questions the value of the sheep erythrocyte as a quantitatively accurate predictive model.

The effect of ascorbic acid on sodium nitrite-induced methemoglobin formation in glucose-6-phosphate dehydrogenase-deficient erythrocytes

Ascorbic acid significantly reduced the occurrence of sodium nitrite-induced methemoglobin (METHB) formation in a dose-dependent manner in erythrocytes from glucose-6-phosphate dehydrogenase (G-6-PD)-deficient humans in vitro. The ascorbic acid treatment, however, also decreased levels of reduced GSH in a dose-dependent manner, a response indicative of oxidant stress to the erythrocyte membrane. The latter findings are inconsistent with the hypothesis that ascorbic acid supplementation in G-6-PD-deficient humans may help compensate for inherently low levels of erythrocyte GSH. Finally, the ascorbic acid-induced reduction of METHB values, while of statistical significance, does not appear to be of clinical significance.

An evaluation of the dorset sheep as a predictive animal model for the response of glucose-6-phosphate dehydrogenase-deficient human erythrocytes to a proposed systemic toxic ozone intermediate, methyl oleate ozonide

Erythrocytes of both glucose-6-phosphate dehydrogenase (G-6-PD)-deficient humans and Dorset sheep, an animal model with an erythrocyte G-6-PD deficiency, responded in a dose-dependent manner to the oxidant stress of methyl oleate ozonide (MOO) as measured by decreases in G-6-PD activity, increases in methemoglobin (METHB) levels, and decreases in GSH. However, the human G-6-PD-deficient erythrocytes were considerably more sensitive to the formation of METHB than the sheep erythrocytes while the reverse was the case for the GSH parameter. The results suggest a qualitative difference in the response of sheep erythrocytes and human G-6-PD-deficient erythrocytes to MOO that seriously questions the value of the sheep erythrocyte as a quantitatively accurate predictive model.

The effect of methyl oleate hydroperoxide, a possible toxic ozone intermediate, on human normal and glucose-6-phosphate dehydrogenase-deficient erythrocytes

Erythrocytes of both normal and glucose-6-phosphate dehydrogenase (G-6-PD)-deficient humans responded in a dose-dependent manner to the oxidant stress of methyl oleate hydroperoxide (MOHP) as measured by decreases in G-6-PD activity, increases in methemoglobin (METHB) levels, and decreases in reduced glutathione (GSH). The G-6-PD-deficient erythrocytes displayed a markedly enhanced sensitivity to MOHP-induced decreases in G-6-PD activity and METHB increases while being less sensitive than normal erythrocytes to changes in GSH levels.

Health effects among newborns after prenatal exposure to ClO2-disinfected drinking water

Because chlorination of potable surface waters may be associated with increased risk of carcinogenicity, substitute methods for the routine disinfection of public water supplies are being explored. As part of this search, it is especially important that the potential health effects of each alternative method should be considered. Chemical treatment of drinking water by chlorine dioxide (ClO2) is a likely alternative mode of disinfection. Two common by-products of the ClO2 disinfection of surface water are chlorate and chlorite. These oxidants may have negative health effects on certain high risk groups. Newborns, in particular, would seem to be at increased risk to red cell damage from oxidant stress. The historical record study being reported here compares the morbidity and mortality experience of newborns in two similar communities, one of which used chlorination and the other which used high levels of chlorine dioxide for potable water disinfection. A statistically significant positive association was found between exposure of the mother to ClO2-treated water during pregnancy and prematurity of the newborn as assessed by the attending physician and by a greater weight loss after birth. The rates of jaundice, birth defects and fetal and neonatal mortality did not differ significantly between communities. Because of the limitations of the study design, the findings reported here should be considered suggestive rather than definitive.

Toxicological effects of chlorite in the mouse

When exposed to a maximum level of 100 ppm chlorine dioxide in their drinking water, neither A/J or C57L/J mice exhibited any hematologic changes. Chlorite exposure under similar conditions produced increases for red blood cells in osmotic fragility, mean corpuscular volume, and glucose-6-phosphate dehydrogenase activity for both strains. Chlorite exposure of pregnant A/J mice resulted in a significant decrease in the weight of pups at weaning and a lower average birth to weaning growth rate. Mice exposed to as much as 100 ppm sodium chlorite (NaClO2) in their drinking water for up to 120 days failed to demonstrate any histopathological changes in kidney structure.

Does cadmium exposure reduce the metabolism of ethanol?

It is proposed that persons exposed to elevated levels of cadmium via occupation, diet, or cigarette smoking will exhibit a diminished capability to metabolize ethanol via the action of the zinc dependent enzyme, alcohol dehydrogenase (ADH). This follows from the observation that cadmium can replace the zinc in liver ADH and inactivate it.

G6PD-deficiency: a potential high-risk group to copper and chlorite ingestion

Although humans may accept fairly large amounts of orally ingested copper (0.25 to 1.0 gm) without visible harmful effects, patients with Wilson's disease, and persons with G6PD deficiency may represent persons at unusual risk to hemolytic anemia from ingestion of Cu(II). This study reports that in vitro exposure of G6PD deficient red blood cells to copper produced marked elevations of methemoglobin and decreases in GSH when compared with normal red cells. Chlorite, a by-product of chlorine dioxide disinfection of water, produced decreases in GSH and G6PD activity, while increasing methemoglobin levels markedly over red cells with normal G6PD activity. The combined action of chlorite and copper was additive in producing increased levels of hemoglobin and decreases in levels of GSH and G6PD deficient cells. The combined ingestion of copper and chlorite may represent an increased risk to persons with G6PD deficiency.

Groups at potentially high risk from chlorine dioxide treated water

Chlorite, a by-product of chlorine dioxide disinfection of water, is a strong oxidant compound that produces markedly exaggerated effects in vitro on red cells of G6PD deficient humans when compared to normal human cells. Levels of methemoglobin are significantly greater and GSH levels significantly lower in the G6PD deficient cells than in normal cells after chlorite exposure. Persons with G6PD deficiency may be 3 to 4 times more likely to develop hemolytic anemia from chlorite exposure as persons with normal activity levels when GSH levels are used as a measure of susceptibility. The proposed use of chlorine dioxide as an alternate disinfectant for drinking water supplies should consider this potential high risk group.

The effects of chlorine dioxide and sodium chlorite on erythrocytes of A/J and C57L/J mice

Because chlorinated surface drinking water supplies have been implicated in an increased risk of cancer, alternative methods of disinfection are being proposed; chlorine dioxide is the most seriously considered. This study reports that chlorine dioxide exposure of two strains of laboratory mice (A/J and C57L/J) to 100 ppm chlorine dioxide in their drinking water for 30 days produced no changes in 11 hematological parameters measured. Chlorite (a product formed from chlorine dioxide disinfection) produced increases in MCV (mean corpuscular volume); osmotic fragility; G6PD (glucose-6-phosphate dehydrogenase) activity; and the number of acanthocytes at exposure to 100 ppm, but not 1.0 or 10.0 ppm. These findings are consistent with membrane damage to the red cell and, in particular, the lipid fraction. Since chlorite is formed at a rate of 50 percent of the chlorine dioxide demand, serious consideration must be given to limiting chlorite formation before chlorine dioxide is adopted as a disinfectant to replace chlorine.

Does the rodent model adequately predict the effects of ozone induced changes to human erythrocytes?

There is an important need to develop animal models to simulate the response of humans to environmental pollutants. The rodent model has been commonly employed to predict the effects of ambient ozone on human RBCs. The use of rodent models for such a purpose is questioned. This challenge is based on the a) ability of mice to significantly enhance ascorbic acid synthesis following ozone stress, b) the ability of ascorbic acid to prevent oxidant [i.e. acetylphenylhydrazine (APH)] stress to human G-6-PD deficient RBCs and c) the lack of ability of humans to synthesize ascorbic acid.

A survey of fungal flora in respiratory therapy equipment

This survey, designed to detect the presence of fungi in respiratory therapy equipment by using a modification of the method of Nazemi et al, indicated significant numbers of fungi in 6 of 30 respiratory therapy devices used in the home, while none of 138 devices used in the hospital showed significant numbers of fungi. Species of fungi detected in large numbers were all yeasts and yeast-like organisms. Additionally, 50% of home devices were found to be moderately to heavily contaminated with either bacteria or fungi, or both, while only 3.6% of the hospital equipment achieved similar levels of contamination (P less than or equal to 0.005), and in these cases, bacteria were the primary contaminants. It was concluded that fungi merited consideration as potential contaminants of respiratory therapy equipment, and that home care respirators presented significantly greater changes for possibly hazardous contamination than did hospital-maintained equipment.

The possible role of hypertension in aggravating hemolytic episodes in G-6PD deficient persons

Approximately 13 percent of American Negro males carry a mutant [A-variant] glucose-6-phosphate dehydrogenase enzyme in their red blood cells that predisposes them to hemolytic episodes following exposure to oxidant drugs such as primaquine. Most hemolytic episodes to standard prophylactic treatment are mild and self-limited, but as many as 2 percent of Negro males develop severe hemolysis when similarly treated. The exaggerated response may be due in part to the combination of G-6-PD deficiency and hypertension since hypertension can cause red cell fragmentation, and the stressed cells of G-6-PD deficient person would be more sensitive to such fragmentation.

Can elevated levels of copper in drinking water precipitate aucte hemolysis in G-6-PD deficient individuals?

The hypothesis that elevated levels of copper in drinking water may be a factor in the precipitation of acute hemolysis in those with a G-6-PD deficiency in their erythrocytes is developed. The present U.S. EPA drinking water standards do not have a primary (or human health) standard for copper but only a secondary standard which is designed to prevent an unacceptable taste. Because of the widespread occurrence of elevated levels of copper in drinking water in areas where the water is corrosive and the households have copper piping, it is recommended that environmental health regulatory agencies develop a risk assessment concerning the effects of copper on those high risk groups who are predisposed to develop a copper induced hemolysis.

Potential health effects of chlorine dioxide as a disinfectant in potable water supplies

Chlorination of potable water supplies high in organics may yield carcinogenic compounds such as trihalomethanes. Chlorine dioxide has been proposed as an alternative disinfectant to chlorine. However, chlorine dioxide is a strong oxidant that forms significant amounts of chlorite when added to potable water supplies, and chlorite is similar to nitrite in its molecular structure and may be similar in its mechanism of methemoglobin production. Nitrites and chlorites are thought to act synergistically to produce MetHb. Neonates and persons with G-*-PD deficiency are likely to be unusually susceptible to MetHb formation from these compounds because their red cells lack the metabolic machinery to adequately protect against oxidant stress. Since male blacks represent the largest population in the U.S. to be G-6PD deficient, Black male neonates may represent the group at highest risk to the use of chlorine dioxide as a disinfectant in the nations water supplies.

The effect of microbial mycolytic agents on Trichophyton rubrum

Chitinolytic microorganisms isolated from forest soil and from healthy gypsy moth larvae (Porthetria dispar (L.) were screened for their ability to lyse Trichophyton rubrum mycelia. A few of these isolates were mycolytic on both autoclaved and on actively growing, intact, T. rubrum mycelia. Supernatants from these isolates, utilizing live T. rubrum as the sole carbon source, showed the same mycolytic ability. Assays of the supernatants for enzymatic activity revealed exocellular, stable enzymes that releases reducing substances including N-acetylglucosamine from the mycelia.