Interactions of Glucocorticoids, NPY and Hypothalamic Serotonin.

Neuropeptide Y (NPY), insulin, corticosterone (CORT) and 5-hydroxytryptamine (5-HT), or serotonin, are all involved in energy homeostasis. To show how they might interact, the effects of NPY on plasma insulin and on 5-HT metabolism in the paraventricular hypothalamic nucleus (PVN), the ventromedial hypothalamic nucleus (VMN), the arcuate nucleus (ARC), and the locus coeruleus (LC) were measured in separate groups of intact, adrenalectomized (ADX), or ADX and CORT replaced Sprague-Dawley rats. Fifteen minutes after ICV injection of NPY, no effect on 5-HT metabolism in the intact animal was observed. 5-HT and its metabolite, 5-HIAA, increased in the PVN as a result of ADX, an effect that was reversed with CORT replacement. NPY also reversed these effects. Similar effects of ADX, CORT replacement and NPY were noted with 5-HIAA in the ARC. This suggests a role for 5-HT in the attenuation of weight gain in ADX animals. NPY also caused an increase in plasma insulin in the CORT replaced animal, but not the intact animal. This was most likely due to an inability of CORT replaced animals to adjust their CORT levels in response to NPY.

Optimal tobramycin dosage in patients with cystic fibrosis--evidence for predictability based on previous drug monitoring.

A retrospective analysis of files of patients with cystic fibrosis and pulmonary exacerbations was performed to investigate whether an individual dosage of tobramycin once established by serum level determination allows a reliable prediction of the adequate dosage in a consecutive exacerbation. All patients hospitalized > or = 2 times between May 1997 and September 1998 with pulmonary exacerbation due to Pseudomonas aeruginosa infection susceptible to tobramycin were included. The initial dosage to tobramycin was 5 mg/kg body weight every 12 h followed by drug level determinations to establish the optimal dose. In a consecutive exacerbation the same dosage per kg body weight was used again and drug level determinations were repeated. Sixteen patients (six female = 38%) with a mean age of 24 years (median: 26 years, range: 9-33) were hospitalized for 49 pulmonary exacerbations (2-6 per patient, mean: 3, median: 2.5). During the first episode of tobramycin treatment in the study period all trough levels were < 2 microg/ml (median: 0.6) and the peak levels were 7.1-16.9 microg/ml (median: 11.9). In four patients the peak level was > 12 microg/ml. In 28 consecutive episodes the dosage of tobra myci n was chosen based on optimal results of previous drug level monitoring and in 27 instances (96%) the previously established optimal dose was confirmed. In five consecutive episodes the tobramycin dosage had been increased erroneously and this resulted in abnormally high peak levels in three cases. These findings suggest that a safe and therapeutic tobramycin dosage in an individual patient with cystic fibrosis is predictable based on a previously established optimal dosage.

Discriminative-stimulus effects of morphine in combination with alpha- and beta-noradrenergic agonists and antagonists in rats.

Studies have shown that the noradrenergic system is involved in the analgesic effects of opioids and in the expression and development of physical signs of opioid withdrawal. The purpose of the present experiment was to determine if the noradrenergic system was involved in the discriminative effects of morphine in rats trained to discriminate 5.6 mg/kg morphine from saline under a fixed-ratio schedule of food presentation. A range of doses of morphine (0.3-10.0 mg/kg) produced dose-dependent increases in morphine-appropriate responding without substantial decreases in response rate. Several experiments were conducted to determine whether a number of noradrenergic agonists and antagonists 1) substitute for morphine or 2) alter the discriminative-stimulus effects of morphine when administered concurrently. The alpha 2 agonist clonidine (0.003-0.1 mg/kg), the alpha 1 antagonist prazosin (0.1-10.0 mg/kg), the alpha 2 antagonist yohimbine (0.1-10.0 mg/kg), the beta 2 agonist salbutamol (0.03-10.0 mg/kg), and the beta antagonist propranolol (1.0-10.0 mg/kg), neither substituted for morphine nor altered the discriminative-stimulus effects of morphine when administered in combination. These data suggest that the noradrenergic system is not involved in the discriminative-stimulus effects of 5.6 mg/kg morphine in rats.

Familial reciprocal translocation t(17;19) (q11.2;q13.2) associated with neurofibromatosis type 1, including one patient with non-Hodgkin lymphoma and an additional t(14;20) in B lymphocytes.

The cosegregation of a reciprocal translocation t(17;19) (q11.2;13.2) with neurofibromatosis type 1 in three generations suggested that the breakpoint on chromosome 17 involved the NF1 gene. In order to map the breakpoint, we analysed DNAs of patients using parts of the NF1 gene as probes. Southern analysis revealed that the chromosome 17 breakpoint lies within intron 23 of the NF1 gene. One of the patients of the family developed a non-Hodgkin lymphoma. An additional translocation t(14;20) (q32;13.1) in his B lymphocytes points to a gene on chromosome 20 that is juxtaposed to the IGH locus on 14q32, and that may be of relevance for the development of this tumor type.