Histopathology and ultrastructure of primary adrenocortical nodular dysplasia with Cushing''s syndrome

The characteristic adrenal lesions of five patients with bilateral primary adrenocortical nodular dysplasia and Cushing's syndrome developing in adolescence are presented histopathologically, and in two cases ultrastructurally. Two of the patients were siblings with additional extra-adrenal lesions such as pigmented spots on the face, myxoid cutaneous tumours and in one case familial cardiac myxoma. The adrenals were small with an uneven surface due to numerous small brown to black pigmented nodules in the inner cortex. The nodules were composed of eosinophilic giant cells filled with lipofuscin granules. The familial cases in addition revealed a pronounced disorganization of the adrenocortical architecture with capsular disruption and infiltration of periadrenal fatty tissue. The early onset of Cushing's syndrome in the second decade, the bilateral involvement of adrenal glands despite ACTH independence and the familial occurrence in combination with other peculiar rare lesions are strongly suggestive of a malformative process of the zona reticularis of the adrenal glands.     

Bioavailability of Aluminum from Drinking Water

Bioavailability of Aluminum from Drinking Water. FULTON, B.,JAW, S., AND JEFFERY, E. H. (1989). Fundam Appl. Toxicol. 12,144–150. Aluminum, present in our drinking water as hydroxideor sulfate, is limited by solubility to 2.5 mg/liter at pH 7.0.This study was carried out to determine if aluminum at dosestypically found in drinking water would accumulate in rat tissuesif a ligand such as citrate at neutral or acid pH is coadministered,or in the absence of citrate at acid pH. Al(OH)₃ or AlCl₃ wasgiven ad libitum in drinking water to male Sprague-Dawley ratsat 0, 0.1, 2.0, or 100 mg/liter, in 4 mM acetate, pH 3.2 (A),4 mM citrate, pH 2.6 (C), 4 mM citrate, pH 7.0 (7C), or distilledwater, pH 7.0(W). After 10 weeks, rats were killed and tissueswere wet-ashed in nitric acid for determination of aluminumby flameless atomic absorption. Copper, iron, and zinc weredetermined by flame atomic absorption. Metal ion concentrationsin tibia, brain, liver, blood, and kidney did not differ significantlybetween treatment groups. Aluminum accumulated in intestinalcells of all 100 mg Al/liter rats, with the C group accumulatingmore aluminum than the A or W groups. In the C group, intestinalaluminum content increased significantly in a dose-dependentmanner. Intestinal iron was decreased significantly in all the100 mg Al/liter groups. Intestinal copper was decreased in theW group at 100 mg Al/liter, with a trend toward a decrease inA and C groups. We conclude that at these low levels studied,aluminum accumulates in intestinal tissue, and that this accumulationis enhanced by citrate ligand. At 100 mg Al/liter, intestinaliron accumulation is decreased, and copper accumulation is marginallydecreased.     

Is group B streptococcal screening during pregnancy justified?

Summary. Twenty-eight per cent of women investigated during pregnancy were carriers of group B streptococci (GBS). The use of broth enrichment was the most significant factor in determining GBS carriage rates. GBS carriage decreased during pregnancy. Transmission of GBS from mother to baby was related to vaginal carriage but rectal carriage in pregnancy was the best predictor of maternal carriage at term. Rectal and vaginal swabs taken at 28 and 36 weeks correctly predicted 92% of intrapartum GBS carriage. Although accurate prediction of intrapartum GBS carriage is possible, mass screening for GBS in pregnancy is unlikely to be cost-effective in those countries with a low incidence of neonatal GBS sepsis.     

An Update on Exposure and Effects of Lead

Lead is perhaps the oldest of industrial toxins, dating hackto Roman times. Despite the historic knowledge of lead, thismetal remains a public health concern today. This is due bothto the pervasiveness of lead in the environment and to the awarenessof toxic effects of lead occurring at exposure levels lowerthan previously thought harmful. At the 1991 Annual Meeting in Dallas, Texas, the Society ofToxicology hosted the symposium: "An Update on Exposure andEffects of Lead." The goal of the symposium was to present anoverview on critical issues associated with lead toxicity—rangingfrom fundamental mechanisms, such as the role of lead bindingproteins, to assessment of the potential effectiveness of leadabatement measures, such as the impact on blood lead of homedeleading. These issues are summarized in Fig. 1 using the four-stageparadigm of risk assessment as described by the National Academyof Science (NRC, 1977). Clearly, understanding potential impactsof lead in humans is interdisciplinary, involving the effortsof toxicologists, pathologists, epidemiolo gists, environmentalchemists, and others. The following is a summary of each of the individual presentations.     

DIMETHYLTHIOUREA, A HYDROXYL RADICAL SCAVENGER, IMPEDES THE INACTIVATION OF METHIONINE SYNTHASE BY NITROUS OXIDE IN MICE

Dimethylthiourea (DMTU), a potent scavenger of hydroxyl radicals,was studied to see if it attenuated the inactivation of methioninesynthase produced by nitrous oxide in mice. Mice were giveni.p. injections of DMTU 0.5–4.0 mg g^–1 or salineand, 1 h after injection, were exposed to 66% nitrous oxidein oxygen for periods of 0.5–8 h. At given times afternitrous oxide exposure, higher methionine synthase activitieswere found in the livers, kidneys and brains of mice injectedwith DMTU than in the salineinjected animals. These higher methioninesynthase activities in the DMTU-treated animals representeda delay in the enzyme inactivation produced by nitrous oxide,as the difference in activities between the DMTU-injected andsaline-injected mice decreased with increasing duration of exposureto nitrous oxide. Greater differences in methionine synthaseactivities between the DMTU- and saline-injected animals wereobserved with increasing doses of DMTU. The rate of enzyme inactivationfollowing exposure to nitrous oxide was greater in liver andleast in brain, and the difference in activities between thetwo groups varied with the organ examined. DMTU exhibited itsgreatest effect in the kidney, where methionine synthase activitieswere nearly doubled in the DMTU 2.0 mg g^–1 injected comparedwith the saline-injected mice after 1-h exposure to 66% nitrousoxide. Following a marked inactivation of methionine synthaseby exposing mice to 66% nitrous oxide for 4 h, injection ofDMTU 2.0 mg g^–1 at the end of exposure to nitrous oxidedid not enhance, but impaired, the recovery of enzyme activity.The findings are consistent with the hypothesis that nitrousoxide combines with the vitamin B₁₂ molecule of methionine synthaseto form hydroxyl radical that reacts with and inactivates theenzyme, and that DMTU slows this inactivation by scavenginghydroxyl radicals A preliminary report of these results was published in Anesthesiology1988; 69: A434 Address for correspondence: Anesthesiology Service (129), VeteransAdministration Medical Center, 4150 Clement Street, San Francisco,CA 94121, U.S.A.