Taurine Failed to Protect against the Embryotoxic Effects of Isotretinoin in the Rat

Taurine Failed to Protect against the Embryotoxic Effects ofIsotretinoin in the Rat AGNISH, N. D., RUSIN, G., AND DINARDO,B. (1990). Fundam. Appl. To.xicol. 15, 249–257. Experimentalevidence exists to indicate that retinoids may act as detergentsto disrupt biological membranes. Taurine, an amino sulfonicacid, has been shown to possess membrane-stabilizing and cytoprotectiveproperties. This study was undertaken to test whether taurinecoadministered with isotretinoin might be able to protect againstthe teratogenic effects of the retinoid. Our study failed tofind any support for this speculation. Whether challenged againsta 75 (mildly teratogenic) or 150 (very teratogenic) mg/kg/daydose of isotretinoin, taurine for the most part worsened theretinoid embryotoxicity. While in a few combinations taurinedecreased the re-sorption or malformation rate associated withisotretinoin, the decrease was, at best, marginal. In no casewas taurine able to decrease these rates to those noted in thecontrols.     

Histochemical and morphological studies on mammalian epidermal peridermal granules

We performed morphological studies on the epidermal peridermal granules (PG) of newborn mice using histological, fluorescent and electron microscopic methods. PG appeared during the 17th to 18th day of foetal life, and remained in the outermost epidermal layers until 5 days after birth. PG were evenly distributed over the entire cutaneous surface of the mouse, except the tail. PG were found to contain protein and corresponded to sites of transglutaminase activity, but they were devoid of lipids and nucleic acids. They could be differentiated clearly from keratohyalin granules. Together, these studies suggest that PG represent a unique epidermal protein product that serves as a marker of late foetal development.     

Anaesthesia for emergency caesarean section

Summary. The Report on Confidential Enquiries into Maternal Deaths in England and Wales 1982–84 (Department of Health 1989) recommends early involvement of the anaesthetist in women having emergency caesarean sections and the use of epidural anaesthesia in preference to general anaesthesia. In an observational prospective study the need for emergency abdominal delivery could be anticipated in 87% of 360 consecutive emergency caesarean sections. Early establishment of epidural analgesia allowed extension, to an appropriate level for the surgery, in 70%. The duty anaesthetist accompanying the obstetric team on three wardrounds a day could be forewarned of anticipated problems in most women who are eventually delivered abdominally.     

Efficacy of Heparin in Peripheral Venous Infusion in Neonates

OBJECTIVE: To determine the efficacy of continuous, low-dose heparin infusion in prolonging peripheral venous catheter patency in neonates. DESIGN: Randomized, prospective study. SETTING: Level III neonatal intensive-care unit. PARTICIPANTS: 113 neonates requiring i.v. therapy. INTERVENTIONS: The neonates were randomly assigned to heparin (n = 63). The heparin group received 1/2 unit of heparin per milliliter of continuous intravenous infusate or intermittent heparin flush. MAIN OUTCOME MEASURES: Low-dose heparin infusion does not make a difference in the duration of peripheral venous catheter patency. The incidence of catheter-related complications in the heparin group is the same as for those receiving no heparin. RESULTS: The mean duration of catheter patency was 62.75 hours in the heparin group and 27.3 hours in the no-heparin group (p = .0001). The occurrence of infection, bleeding, and extravasation injury was zero in the sample studied. The incidence of phlebitis was 18 cases in 132 (13%) in the heparin group and 13 cases in 122 (10%) in the no-heparin group. According to chi-square analysis, the difference between groups was not statistically significant (p greater than .05). CONCLUSION: Low-dose heparin infusion in peripheral venous catheters in neonates increased the duration of intravenous catheter patency (p = .0001) without increased risks of bleeding, infection, phlebitis, or extravasation injury.     

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.     

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.