Fluoride-fiber-based side-pump coupler for high-power fiber lasers at 2.8 µm.

A side-pump coupler made of fluoride fibers was fabricated and tested. The tested device had a coupling efficiency of 83% and was driven with an incident pump power of up to 83.5 W, demonstrating high-power operation. Stable laser output of 15 W at a wavelength of around 2.8 µm was achieved over 1 h when using an erbium-doped double-clad fiber as the active medium. To the best of our knowledge, this is the first time a fluoride-glass-fiber-based side-pump coupler has been developed. A test with two devices demonstrated further power scalability.

[Changes in serotonin metabolism in pre-eclampsia]. / Veränderungen des Serotoninstoffwechsels bei Präeklampsie.

Several complications of pregnancy have been reported to be associated with alterations of serotonin (5-HT). This study describes the changes in 5-HT metabolism in patients with preeclampsia. Our examination findings should explain if there are elevated 5-HT and 5-HIAA concentrations in urine and serum of women with preeclampsia. On the other hand it should be proved if the observed chances are due to a decreased kidney function and if there is an important prognostic factor to detect asymptomatic preeclamptic patients. 5-HT and its main metabolite 5-hydroxy-indol-acetic acid (5-HIAA) was evaluated in serum and urine of 24 pregnant women with preeclampsia and of 27 pregnant women without preeclampsia in the last month of pregnancy, within 24 hours after delivery and at the fourth day post partum. Besides 5-HIAA was ascertained in 24-h urine from the 24th week of pregnancy until after delivery. 5-HIAA excretion increased continuously during pregnancy independently of whether the patients developed preeclampsia. A significant less increase and lower concentration of 5-HIAA pre and post partum were observed in preeclamptic patients when compared to non-preeclamptic patients. We noticed a remarkably lower 5-HIAA excretion and a higher concentration of 5-HT in women with preeclampsia. Preeclamptic patients demonstrate a lower decrease of 5-HIAA and a significantly greater increase of 5-HT than women without preeclampsia. These results could be explained by a decreased metabolism of 5-HT due to the placental MAO. The changes observed in our study are not due to a decreased kidney function because creatinine concentrations in women with and without preeclampsia were comparable. Our results indicate that 5-HIAA-/creatinine ratio might be an important prognostic factor.

[Effect of pregnancy and labor on serotonin metabolism]. / Einfluss von Schwangerschaft und Geburt auf den Serotoninstoffwechsel.

Several complications of pregnancy have been reported to be associated with alterations of serotonin (5-hydroxytryptamine; 5-HT) metabolism. Reported data regarding changes of 5-HT metabolism in pregnancy are partially contradictory. The presented study tries to describe pregnancy-associated changes in 5-HT metabolism. Urine and blood samples were taken from 20 pregnant women 4 weeks before, within 24 hours and on the 4th day following delivery. 17 non-pregnant age-matched women served as controls. 5-HT and its main metabolite 5-hydroxyindoleacetic acid (5-HIAA) were analysed. We observed a continuously increasing production and excretion of unbound 5-HT and 5-HIAA during pregnancy. Four days after delivery 5-HT production returned to baseline levels, while excretion remained elevated. 5-HIAA excretion increased in pregnancy and return to baseline levels on the day following delivery. Increased 5-HT metabolism and excretion results in a decreased 5-HT serum concentration despite increased 5-HT production during pregnancy. Our results help to understand the contradictory observations of elevated 5-HT production on the one hand and decreased 5-HT activity during pregnancy on the other.