Production and decay of element 114: high cross sections and the new nucleus 277Hs

The fusion-evaporation reaction 244Pu(48Ca,3-4n){288,289}114 was studied at the new gas-filled recoil separator TASCA. Thirteen correlated decay chains were observed and assigned to the production and decay of {288,289}114. At a compound nucleus excitation energy of E{*}=39.8-43.9  MeV, the 4n evaporation channel cross section was 9.8{-3.1}{+3.9}  pb. At E^{*}=36.1-39.5  MeV, that of the 3n evaporation channel was 8.0{-4.5}{+7.4}  pb. In one of the 3n evaporation channel decay chains, a previously unobserved α branch in 281Ds was observed (probability to be of random origin from background: 0.1%). This α decay populated the new nucleus 277Hs, which decayed by spontaneous fission after a lifetime of 4.5 ms.

Upregulation of cyclooxygenase-2 and thromboxane A2 production mediate the action of tumor necrosis factor-alpha in isolated rat myenteric ganglia

Intact myenteric ganglia from 4- to 10-day-old rats were isolated from the small intestine. The preparations were cultured overnight, and drugs were applied within this time frame (20 h). Whole cell patch-clamp technique was used to measure basal membrane potential and carbachol-induced depolarization at neurons within these ganglia. Pretreatment with TNF-alpha (100 ng/ml) hyperpolarized the membrane (from -31.0 +/- 2.7 mV under control conditions to -61.2 +/- 3.2 mV in the presence of the cytokine) and potentiated the depolarization induced by carbachol (from 5.2 +/- 0.7 mV under control conditions to 27.5 +/- 2.0 mV in the presence of the cytokine). These effects were mimicked by carbocyclic thromboxane A2 (10(-6) mol/l), a stable thromboxane A2 agonist. The TNF-alpha action was inhibited by 1-benzylimidazole (2 x 10(-4) mol/l), a thromboxane synthase inhibitor, and BAY U 3405 (5 x 10(-4) mol/l), an inhibitor of thromboxane receptors. Measurements of thromboxane production in the supernatant of the culture revealed an increased concentration of thromboxane B2, the stable metabolite of thromboxane A2, after exposure to TNF-alpha. Immuncytochemical staining for cyclooxygenase-2 (COX-2) and the neuronal marker microtubule-associating protein-2 revealed an upregulation of COX-2 in myenteric neurons after exposure to the cytokine. These results demonstrate the involvement of COX-2 and the subsequent production of thromboxane A2 in the presence of TNF-alpha.

[Investigations for pathogenesis of depression of lymphocyte transformation in chronic uremia (author's transl)]

In order to investigate the depressive effect of the hypothetical low molecular weight "uremic toxins" methylguanidine and phenol on lymphocyte transformation these substances were added to lymphocyte cultures with increasing concentrations. 3H-thymidine uptake and LDH-activity in the supernatant culture medium as a parameter of continuous cell destruction were analyzed after incubation for 5 days. Both substances induced in spontaneous as well as in PHA-stimulated cultures dose-dependent depression of 3H-thymidine uptake and simultaneous increase in LDH-activity. Thus the effect of both toxins may be cytotoxic depression of lymphocyte viability. Furthermore in the same arrangement-way higher molecular weight metabolites from urine of healthy and chronic uremic persons were added in increasing concentrations to lymphocyte cultures. The same result: dose-dependent depression of transformation and increase of LDH-activity was slightly diminished by urine metabolites from uremic patients as compared to healthy persons. This may be due to a shift toward non-toxic compounds. But as these metabolites are excreted in 20-30 fold larger quantities in chronic renal insufficiency, an accumulation in the serum and classification as "uremic toxins" can be excluded.