The regulation of reactive oxygen species production during programmed cell death

Reactive oxygen species (ROS) are thought to be involved in many forms of programmed cell death. The role of ROS in cell death caused by oxidative glutamate toxicity was studied in an immortalized mouse hippocampal cell line (HT22). The causal relationship between ROS production and glutathione (GSH) levels, gene expression, caspase activity, and cytosolic Ca2+ concentration was examined. An initial 5-10-fold increase in ROS after glutamate addition is temporally correlated with GSH depletion. This early increase is followed by an explosive burst of ROS production to 200-400-fold above control values. The source of this burst is the mitochondrial electron transport chain, while only 5-10% of the maximum ROS production is caused by GSH depletion. Macromolecular synthesis inhibitors as well as Ac-YVAD-cmk, an interleukin 1beta-converting enzyme protease inhibitor, block the late burst of ROS production and protect HT22 cells from glutamate toxicity when added early in the death program. Inhibition of intracellular Ca2+ cycling and the influx of extracellular Ca2+ also blocks maximum ROS production and protects the cells. The conclusion is that GSH depletion is not sufficient to cause the maximal mitochondrial ROS production, and that there is an early requirement for protease activation, changes in gene expression, and a late requirement for Ca2+ mobilization.     

Detection of coronary stenoses on source and projection images using three-dimensional MR angiography with retrospective respiratory gating: preliminary experience

OBJECTIVE: Our objective was to study the ability of three-dimensional MR angiography with retrospective respiratory gating to reveal stenoses in proximal coronary arteries on source and projection images. CONCLUSION: Proximal coronary artery stenoses can be identified using three-dimensional MR angiography with retrospective respiratory gating, both with projection images and on source images alone. Reasons for missed lesions included collateral vessels and retrograde flow distal to complete occlusion and volume averaging of vessels with adjacent structures. Causes of false-positive interpretations included small foci of decreased signal intensity distal to complete occlusion, partial volume effects on individual partitions, and regions of distal vessels leaving the imaging plane.     

Tumor register: information system for tumor centers (author's transl)

The different activities in the scope of the tumor center already shows in the multiplicity of concepts for which incidence register, therapy register, clinical register or the supplies register are only a few examples. Such terms circumscribe a few interests from the therapeutic, epidemiologic or clinical and scientific aspects, which are projected on tumor centers as an expectation or a duty. From the compilation of these interests a bundle of unspecific aims results for which a classification according to various levels of information is suggested. Only cooperation of all levels makes possible a tumor register as an information system for medicine which supports the tasks of all those involved and makes the questions of the population more easily and more quickly answerable.     

Ein Beitrag zur Analytik der Fumars?ure und der Maleins?ure in Lebensmitteln

Zusammenfassung Zur Prüfung der Frage, in welchom Ausmaß Fumarsäure bei Backprozessen und bei indirekter Bestrahlung mit Ultraviolettlicht eine Umwandlung in Maleinsäure erfährt, wurde ein geeignetes analytisches Verfahren entwickelt. Die Isolierung der in Rede stehenden Säuren aus Gebäcken erfolgt aus einem wäßrigen Auszug durch Adsorption an Ionenaustauscherharz und anschließende Elution mit Ammonium-hydrogencarbonatlösung. Zur qualitativen und quantitativen Erfassung der Fumarund Maleinsäure wird eine dünnschichtchromatographische Methode beschrieben. Bei indirekter Bestrahlung mit ultraviolettem Licht erfolgt keine nachweisbare Isomerisierung wäßriger Fumarsäurelösungen. Im wäßrigen Medium beginnt oberhalb von 180° C eine Isomerisierung der Fumarsäure zu Maleinsäure. Überlagert wird dieser Prozeß durch Sublimation der Säuren sowie durch Isomerisierung der Maleinsäure zu Fumarsäure. Dadurch verringert sich der allein in der Brotkruste lokalisierte Anteil der Maleinsäure weiter. Für Brot und Keks wird auf Grund der Versuchsergebnisse das Verhalten der Fumarsäure beim Backprozeß diskutiert.     

Left colon gangrene after acute inferior mesenteric artery occlusion

We report here an experience with five patients, aged 58 to 70, suffering gangrene of the left colon after spontaneous inferior mesenteric artery occlusion. All cases were the result of arteriosclerosis; in two, small aortic aneurysms were present and might have been responsible for emboli to the inferior mesenteric artery. The dead bowel was resected in all patients; three patients survived. No primary anastomoses were done and they are not recommended. Because ligation of the patent inferior mesenteric artery has been done so often without ill effects during aortic surgery, the collateral circulation to the left colon can be considered excellent. Gangrene is therefore rare and requires major interference with collateral circulation by emboli or arteriosclerotic occlusion. The clinical symptoms and signs may be confusing.     

Thromboembolism complicating surgery for cervical and uterine malignancy: incidence, risk factors, and prophylaxis

Venous thromboembolism is a leading cause of death and morbidity after extended surgery for early malignancies of the cervix and uterus. Two hundred eighty-one patients who underwent such surgery were retrospectively evaluated for associated risk factors, the incidence of clinically significant thromboembolic complications, and prophylactic value of low-dose heparin and antiembolism stockings. Significant thromboemboli were encountered in 7.8% of patients postoperatively and accounted for the only 4 postoperative deaths. Forty-five percent of patients who developed thromboemboli did so after discharge from the hospital. The preoperative risk factors found to be associated with thromboembolism, in order of statistical significance, were weight in excess of 85.5 kg, advanced clinical stage of malignancy, and radiation therapy within 6 weeks of the operative procedure. Low-dose heparin therapy and the use of antiembolism stockings as preventative measures did not appear to reduce the incidence of thromboembolic complications. A prospective study will be necessary to evaluate definitely the effectiveness of various therapeutic modalities on thromboembolism in gynecologic oncology patients.     

Electron-beam treatment of aromatic hydrocarbons that can be air-stripped from contaminated groundwater. 2. Gas-phase studies

The electron-beam (EB) degradation of volatile aromatics (benzene, toluene, ethylbenzene, xylenes: BTEX) in groundwater strip gas, which in the present work has been modeled by the introduction of the desired aromatic(s) to a stream of air or another gas, such as oxygen, is initiated essentially by the addition of *OH radicals to the aromatic ring, giving rise to hydroxycyclohexadienyl radicals, which form the corresponding peroxyl radicals upon addition of oxygen. As studied in some detail with benzene as a BTEX representative, various reactions of these lead to numerous oxidation products in a cascade of reactions, including the decomposition of products under the prevailing conditions of high turnover of the initial aromatic. Importantly, hydroxycyclohexadienylperoxyl radical formation is partly reversible, and the reactions of the hydroxycyclohexadienyl radicals, which thus have a significant presence in these systems, must therefore also be taken into consideration. In the gas phase, in contrast to the aqueous phase (see Part 1), the reactions of the hydroxycyclohexadienyl radicals lead to oligomeric products that appear to contribute, in addition to ionic clusters, to nucleation for the aerosols observed. Various nitrated products, among them nitrophenols, are observed when air is used for the stripping. However, these studies did not clear the pilot plant stage, since BTEX degradation using a bioreactor carried out in parallel was so successful that the EB technology was judged to be noncompetitive. As for the latter, expensive equipment consisting of a stripper, the EB machine, and an aerosol precipitator would be required. The condensed aerosols are biorefractory and would require further treatment for detoxification.     

POLYCHAR-10 World Forum on Polymer Applications &; Theory in 2002

A report from POLYCHAR-10 is provided. An introduction to the following papers presented at the POLYCHAR-10 Forum is given. A small selection of the authors and titles of the papers presented is listed. Prizes awarded are listed along with the composition of the Prize Committee. Some research groups of high activity which are represented at POLYCHAR every year are named. Electronic Publication     

Nitrous oxide emission as affected by liming an acidic mineral soil used for arable agriculture

The effect of liming an acidic mineral soil (Dystric Nitosol from southern China), used for arable agriculture, on N₂O emission was studied in an incubation experiment. After the soil pH had been raised from pH 4.4 to 5.2, 6.7 and 8.1, soil samples were either amended with NH₄ ⁺ and incubated aerobically, favoring nitrification or, after application of NO₃ ^–, the incubation took place under anaerobic conditions, favoring denitrification. Gas sampling for N₂O determination and soil analyses were performed at regular intervals up to 13 days. Under nitrification conditions only small N₂O emission rates were observed (max. 6 g N kg^–1 d^–1) with significant differences between high and low pH values during the first 2 days of incubation. The nitrifying activity was low, even with high pH, and this, together with good aeration conditions, could partly explain the small N₂O evolution. During denitrification, however, cumulative N₂O emissions reached much higher values (1600 g N kg^–1 in comparison to 40 g N kg^–1 under nitrification conditions). N₂O emission during denitrification was significantly enhanced by increasing soil pH. Under alkaline conditions (pH 8.1) a large nitrite accumulation occurred, which was in line with the highest nitrate reductase activity determined in this treatment. The limited availability of organic carbon is probably the main reason for the absence of further reduction of NO₂ ^– to N₂O or N₂. At pH 6.7 the total N₂O emission was slightly higher than at pH 8.1, although the start of pronounced emissions was retarded and only small amounts of NO₂ ^– accumulated. Acid soil conditions caused either negligible (pH 4.4) or only small (pH 5.2) N₂O emissions. It can be concluded that these kinds of soil, used alternatively for production of upland crops or paddy rice, are prone to high N₂O emissions after flooding, particularly under neutral to alkaline conditions. In order to avoid major N₂O evolution and accumulation of nitrite, which can be leached into groundwater, the pH should not be raised to values above 5.5–6.