In the present study the effects of artificial magnetic fields on pineal serotonin-N-acetyltransferase (NAT) activity and melatonin content in male Sprague-Dawley rats were investigated to study the secretory activity of the pineal gland. Experimental inversion of the horizontal component of the natural magnetic field, performed at night-time, led to a significant decrease of both parameters investigated. During day-time, this effect was less conspicuous. During night-time, inversion of the horizontal component is followed by a reduced pineal secretory activity for about 2 h. After 24 h exposure to the inverted horizontal component, return to the natural condition was followed by a renewed clear depression of pineal NAT activity and melatonin content, indicating that the main stimulus is not the inverted magnetic field itself but rather its change. Changing the inclination of the local magnetic field from 63 degrees to 58 degrees, 68 degrees or 78 degrees, respectively also decreased the secretory activity of the rat pineal gland.

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A retrospective study was conducted to determine the significance of intensive care management on outcome after liver transplantation (LTx) in children. Of 195 transplants performed in 162 children, factors affecting morbidity and mortality were documented during the post-operative intensive care unit (ICU) stay. To assess the gain in experience of ICU management, we compared mean ventilation time and stay in the ICU as well as mortality, incidence of surgical complications, infections, and rejection episodes, during three different time-periods (October 1991-August 1994, September 1994-July 1996, and August 1996-February 1998). The time spent by patients in the ICU (9.7 days vs. 7.9 days vs. 4.7 days, p < 0.001) and time on ventilation (5.2 days vs. 3.1 days vs. 1.2 days, p < 0.001) were significantly reduced over the duration of the study. The overall mortality was 18.0% (n = 30) and 76.7% (n = 23) of these deaths occurred during the early post-operative period in the ICU. The incidence of severe surgical complications decreased significantly over time, and the application of intra-operative Doppler ultrasound since 1994 led to detection of 27 correctable vascular complications. The overall incidence of acute cellular rejection episodes in our center was 64.1%: 43.5% of the infectious episodes occurred in the ICU (bacterial 70.2%, viral 12.3%, and fungal 17.5%). The main side-effect from immunosuppressive drugs was arterial hypertension in 29% of the patients. We conclude that our efforts to improve intensive care management and monitoring were the key elements in reducing morbidity and mortality after pediatric LTx.

Congenital adrenal hyperplasia is a group of autosomal recessive disorders second most often caused by deficiency of steroid 11-hydroxylase (CYP11B1) due to mutations in the CYP11B1 gene. We studied the functional and structural consequences of two novel missense mutations (W116C, L299P) and an in-frame 3-bp deletion (DeltaF438) in the CYP11B gene, detected in three unrelated families. All patients are suffering from classical CYP11B1 deficiency. In vitro expression studies in COS-7 cells revealed a decreased CYP11B1 activity in the W116C mutant to 2.9 +/- 0.9% (sd) for the conversion of 11-deoxycortisol to cortisol. The L299P mutant reduced the enzymatic activity to 1.2 +/- 0.9%, whereas the DeltaF438 mutation resulted in no measurable residual CYP11B1 activity. Introduction of these mutations in a three-dimensional model structure of the CYP11B1 protein provides a possible explanation for the in vitro measured effects. We hypothesize that the W116C mutation influences the conformational change of the 11-hydroxylase protein necessary for substrate access and product release. The L299P mutation causes a change in the position of the I helix relative to the heme group, whereas the DeltaF438 mutation results in a steric disarrangement of the heme group relative to the enzyme. Studying the enzyme function in vitro helps to understand the phenotypical expression and disease severity of 11-hydroxylase deficiency, which is the basis for accurate genetic counseling, prenatal diagnosis, and treatment. Moreover, the combination of in vitro enzyme function and molecular modeling provides new insights in cytochrome P450 structural-functional relationships.

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We investigated the ontogeny of melatonin synthesis during fetal maturation by measuring the melatonin (MLT) and 6-hydroxymelatonin sulfate (MLTS) excretion in the urine of male infants aged 2-7 days and gestational age 26-42 weeks. We found a negative correlation between advancing gestational age and the MLT and MLTS excretion expressed as total 24-h amount, ratio of 24-h amount to creatinine and ratio of 24-h amount to body surface area. The ratio of MLT to MLTS was found to be about ten times higher in the study group than in prepubertal children, which might reflect the immaturity of hepatic sulfation capacities. The total amount of excreted MLT and MLTS was only one-tenth the prepubertal values. No day/night differences in MLT and MLTS excretion could be detected. We conclude that the fetal pineal gland is capable of a limited melatonin synthesis from the 26th week of gestation onwards, with decreasing values reaching its nadir around term. This indicates that the amount of fetal MLT excretion is not determined by synthesizing capacities of the pineal gland but by the development of neural connections to the pineal gland.

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Hypothalamic hamartomata are benign malformations of the brain consisting of heterotopic nervous tissue, and are often associated with precocious puberty and gelastic seizures in early childhood. We report for the first time the melatonin plasma values of a girl with central precocious puberty and gelastic seizures due to a hypothalamic hamartoma. The melatonin plasma levels were low for the chronological age but appropriate for the pubertal status, making a causal relationship between lowered melatonin plasma levels and precocious puberty possible.