Environmental endocrine disruptors: Effects on the human male reproductive system

Incidences of altered development and neoplasia of male reproductive organs have increased during the last 50 years, as shown by epidemiological data. These data are associated with the increased presence of environmental chemicals, specifically "endocrine disruptors," that interfere with normal hormonal action. Much research has gone into testing the effects of specific endocrine disrupting chemicals (EDCs) on the development of male reproductive organs and endocrine-related cancers in both in vitro and in vivo models. Efforts have been made to bridge the accruing laboratory findings with the epidemiological data to draw conclusions regarding the relationship between EDCs, altered development and carcinogenesis. The ability of EDCs to predispose target fetal and adult tissues to neoplastic transformation is best explained under the framework of the tissue organization field theory of carcinogenesis (TOFT), which posits that carcinogenesis is development gone awry. Here, we focus on the available evidence, from both empirical and epidemiological studies, regarding the effects of EDCs on male reproductive development and carcinogenesis of endocrine target tissues. We also critique current research methodology utilized in the investigation of EDCs effects and outline what could possibly be done to address these obstacles moving forward.

The impact of extracorporeal membrane oxygenation on survival in pediatric patients with acute respiratory failure. Pediatric Critical Care Study Group

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) has been used with increasing frequency in the treatment of acute respiratory failure in pediatric patients. Our objective in this study was to test the hypothesis that ECMO improves outcome in pediatric patients with acute respiratory failure.

DESIGN

Multicenter, retrospective cohort analysis.

SETTING

Forty one pediatric intensive care units participated in the study under the auspices of the Pediatric Critical Care Study Group.

PATIENTS

All pediatric patients admitted to the participating institutions with acute respiratory failure during 1991 were included. Patients with congenital heart disease, contraindications to ECMO, or incomplete data were excluded, yielding a data set of 331 patients from 32 hospitals.

INTERVENTIONS

Conventional mechanical ventilation, high-frequency ventilation, and extracorporeal membrane oxygenation.

MEASUREMENTS AND MAIN RESULTS

Multivariate logistic regression analysis was used to identify factors associated with survival. In a second analysis, pairs of ECMO and non-ECMO patients, matched by severity of disease and respiratory diagnosis, were compared. The use of ECMO (p = .0082), but not the use of high-frequency ventilation, was associated with a reduction in mortality. Other factors independently associated with mortality included oxygenation index (p < .0001), Pediatric Risk of Mortality score (PRISM) (p < .0001) and the Paco2 (p = .045). In 53 diagnosis- and risk-matched pairs, there was a significantly lower mortality rate (26.4% vs. 47.2%; p < .01) in the ECMO-treated patients. When all patients were stratified into mortality risk quartiles on the basis of oxygenation index and PRISM score, the proportion of deaths among ECMO-treated patients in the 50% to 75% mortality risk quartile was less than half the proportion in the non-ECMO treated patients (28.6% vs. 71.4% p < .05)> No effect was seen in the other quartiles.

CONCLUSIONS

The use of ECMO was associated with an improved survival in pediatric patients with respiratory failure. The lack of association of outcome with treatment in the ECMO-capable hospital or with another tertiary technology (i.e. high-frequency ventilation) suggests that ECMO itself was responsible for the improved outcome. Further studies of this procedure are warranted but require broad-based multi-institutional participation to provide sufficient statistical power and sensitivity to demonstrate efficacy.

Is dantrolene safe to administer in sepsis? The effect of dantrolene after endotoxin administration in dogs and rats

Hyperthermia from septic shock may be indistinguishable from malignant hyperthermia. Dantrolene may be given in septicemia if the diagnosis is unclear. To determine if dantrolene is safe to use in sepsis, two studies were performed. In study 1, 18 anesthetized dogs in which profound septic shock was induced with 5 mg/kg of intravenous Escherichia coli endotoxin were randomized to receive (30 min later) intravenous injections of 10 mg/kg of dantrolene solution, the diluent of dantrolene, or maintenance intravenous fluids alone. The use of dantrolene solution and the diluent of dantrolene resulted in similar but transient statistically significant increases in the cardiac filling pressures and cardiac outputs and decreases in the vascular resistances compared with the control dogs. In a second study, 185 rats were randomized into five equal groups. Groups 1, 2, and 3 received 15 mg/kg of intraperitoneal Escherichia coli endotoxin followed 30 min later by 10 mg/kg of dantrolene solution, the diluent of dantrolene, or normal saline. Groups 4 and 5 received normal saline followed by dantrolene or normal saline. The survival of groups 1, 2, and 3 was less at 24 h (P less than 0.0001) than that of either control group, but was not significantly different from one another. The results suggest dantrolene can be administered safely under clinical conditions where the cause of hyperthermia and shock cannot clearly be ascribed to malignant hyperthermia or septicemia.

Pharmacodynamic response to ionized calcium during acute sepsis

Ionized Ca (Ca2+) is essential for maintaining physiologic functioning in the cardiovascular system (CVS). Sepsis affects the CVS by several mechanisms and is associated with decreased serum Ca2+. The pharmacodynamic response of the CVS to serum Ca2+ alteration was compared in acutely septic and nonseptic dogs at serum Ca2+ levels of 50%, 100%, 150% and 200% of normal baseline values. Serum Ca2+ alterations caused similar changes in both groups, although finite differences existed between septic and nonseptic subjects. Ca manipulation produced limited differences in the response of mean arterial pressure, cardiac output, left ventricular dP/dtmax, systemic (SVR) and pulmonary (PVR) vascular resistance between septic and nonseptic subjects. PVR and SVR demonstrated opposite responses during hypocalcemia; PVR was lower than baseline in both groups, whereas SVR was higher at the 50% level. No difference was evident for total oxygen consumption (VO2) or heart rate. In view of the limited differences in response and the failure to improve systemic VO2, serum Ca2+ supplementation does not afford any additional benefit in this experimental model of acute sepsis.

Comparison of internal and external jugular cannulation of the central circulation in the pediatric patient

Percutaneous catheterization of the central circulation via the internal jugular vein was compared to cannulation via the external jugular vein, in a retrospective review of 200 pediatric patients. The internal approach resulted in an 86% rate of successful cannulations with 99.9% of the catheters positioned in the thorax; this technique was accompanied by an 8% incidence of carotid artery puncture. The external jugular route eliminated the risk of carotid artery puncture; however, it was successful in only 65% of the attempts, and 14% of the successful cannulations had catheter tips incorrectly positioned outside the thorax.

Communicating hydrocephalus secondary to venous complications following intraatrial baffle operation (mustard procedure) for d-transposition of the great arteries

A 39-month-old male had macrocephaly and communicating hydrocephalus secondary to superior vena cava (SVC) obstruction which was a postoperative complication of an intraatrial baffle operation (Mustard procedure) performed at age 10 months. Computerized tomography revealed progressive hydrocephalus. Cardiac catheterization showed an SVC pressure of 24 mm Hg. IVC and systemic vein atrium pressures were 5 mm Hg. Cineangiograms showed huge azygos collaterals from SVC to IVC. The operation was revised using a Dacron baffle instead of the original pericardial baffle. Nine months postoperatively, the head circumference was 55.0 cm and there was no clinical evidence of SVC obstruction.