CO2 isotope analyses using large air samples collected on intercontinental flights by the CARIBIC Boeing 767.

Analytical details for 13C and 18O isotope analyses of atmospheric CO2 in large air samples are given. The large air samples of nominally 300 L were collected during the passenger aircraft-based atmospheric chemistry research project CARIBIC and analyzed for a large number of trace gases and isotopic composition. In the laboratory, an ultra-pure and high efficiency extraction system and high-quality isotope ratio mass spectrometry were used. Because direct comparison with other laboratories was practically impossible, the extraction and measurement procedures were tested in considerable detail. Extracted CO2 was measured twice vs. two different working reference CO2 gases of different isotopic composition. The two data sets agree well and their distributions can be used to evaluate analytical errors due to isotope measurement, ion corrections, internal calibration consistency, etc. The calibration itself is based on NBS-19 and also verified using isotope analyses on pure CO2 gases (NIST Reference Materials (RMs) and NARCIS CO2 gases). The major problem encountered could be attributed to CO2-water exchange in the air sampling cylinders. This exchange decreased over the years. To exclude artefacts due to such isotopic exchange, the data were filtered to reject negative delta18O(CO2) values. Examples of the results are given.

Isotope analysis of hydrocarbons: trapping, recovering and archiving hydrocarbons and halocarbons separated from ambient air.

It is argued that isotope analysis of atmospheric non-methane hydrocarbons (NMHCs) and, in particular, the analysis of the deuterium/hydrogen (D/H) ratio is valuable because the dominant self-cleansing property of the troposphere is based on the OH radical which removes, e.g., CH4 and other alkanes by H-atom abstraction, which induces large kinetic isotope effects. The major obstacle in applying D/H isotope analysis to atmospheric NMHCs is not only the low abundance of D itself but, in particular, the low concentrations of NMHCs in the parts per trillion range. We show how a selection of NMHCs can be quantitatively separated from 300 L air samples together with CO2 as carrier gas matrix, by using high efficiency cryogenic traps. After diluting the extracted NMHC mixtures with hydrocarbon free air, and determining the mixing ratios, good agreement with original whole air sample analysis exists for alkanes and several halocarbons. For unsaturated hydrocarbons and some other halocarbons the extraction and recovery yield under the given conditions fell considerably, as a function of boiling point. Furthermore, the mixture of NMHCs in the CO2 matrix is proven to remain unchanged over several years when conveniently stored in glass ampoules. The 'extracts' or 'concentrates' of condensables extracted from larger air samples will enable the D/H isotope analysis of ultra trace gases in the atmosphere.

3-Aminobenzamide enhances dexamethasone-mediated mouse thymocyte depletion in vivo: implication for a role of poly ADP-ribosylation in the negative selection of immature thymocytes.

3-Aminobenzamide (3-ABAm), an inhibitor of poly ADP-ribosylation, was here found to remarkably enhance the dexamethasone (Dex)-mediated depletion of total mouse thymocytes within 24 h post-injection, when given i.p. in combination with Dex. After treatment the total thymocytes were fractionated by Percoll gradient centrifugation into two mitogen-unresponsive (high- and medium-density) and one mitogen-reactive (low-density) subpopulations and these were analyzed for the phenotypic expression of CD4 and CD8 antigens. Treatment with Dex alone most extensively depleted the high- and medium-density thymocytes and also those expressing both CD4 and CD8 double positive (DP) phenotypes in all three subpopulations. The CD4+ and CD8+ single positive (SP) and CD4-CD8- double negative (DN) subsets, in the low-density subpopulation in particular, were most resistant to the Dex-mediated depletion, thus giving rise to an enrichment of SP (2-fold) and particularly DN subset in the medium- and low-density populations (5-fold) recovered. 3-ABAm, which alone increased the total thymocyte number up to 2-fold, had no effect on the distribution of phenotypic subsets. However, the inhibitor, when given in combination with Dex, additionally depleted all four phenotypic subsets up to one-third of the levels with Dex alone, except for those of medium-density subpopulation. Because the non-inhibitor, 3-aminobenzoate, had no potentiating effect, our present results, together with our previous in vitro studies, indicate a role for the DNA repair cofactor poly ADP-ribose in the intrathymic death by apoptosis and depletion of thymocytes, especially those of DP subset in the high-density, functionally immature population.

Rehabilitation of children with brain tumors.

Brain tumors are the most common type of solid tumors in childhood. It has only been over the past 20 years that the majority of children with intracranial tumors are surviving. Children who survive their tumors may do so with significant disabilities resulting from the tumor or its treatment, and are presenting a new challenge in pediatric rehabilitation. In this article, we will discuss the epidemiology and characteristics of the major types of brain tumors that occur in children, the multimodality approach to tumor treatment along with the major complications of the interventions that have implications for the quality of survival, the types of deficits in function that occur most commonly in children who survive their tumors, and the team approach to rehabilitation of children with disabilities due to brain tumors.

Multidrug transport in human autoimmune T line cells and peripheral blood lymphocytes.

We studied multidrug transport in human autoimmune T line cells and peripheral blood leukocytes, because multidrug transport is pleiotropically limiting the intracellular accumulation of immunosuppressive and chemotherapeutic agents. We observed that a subpopulation of peripheral blood leukocytes containing CD4+, CD8+ and Ig+ lymphocytes expressed a multidrug transport system. Lymphocytic multidrug transport was seen with all peripheral blood samples analyzed, but showed considerable variations between individuals. In further studies with human lymphocytic cell lines multidrug transport was seen with 18/23 human CD4+ T cell lines. Interestingly, expression of multidrug transport was independent of T cell activation. No significant transport was observed with EBV-transformed human B lymphocytes, rat T line cells or rat, mouse, or guinea pig leukocytes.

The neurotoxicological aspects of the toxic oil syndrome (TOS) in Spain.

The pathomechanism of the Spanish mass oil poisoning, which affected more than 20,000 people in the spring of 1981 and has so far caused more than 500 deaths, has not yet been clarified. Subsequent to a toxic-allergic initial phase of the disease with fever as well as lung and skin manifestations, 10 to 20% of the patients, after passing through an interval of reduced symptoms, entered a second disease phase characterized by marked vasculitis and fibrosis in diverse organ systems. The most frequent manifestation type involved in this connection was a severe neuromyopathy with pronounced joint contractures and skin alterations. A survey of the disease course is presented on the basis of our own examinations at the Centro Especial Ramon y Cajal as well as morphological studies on nerve-muscle and brain tissue, chemical analysis studies with oil samples from affected families and the literature available so far.

Hemoperfusion for organic mercury detoxication?

A case is reported with suicidal ingestion of 125 g Ceresan, a fungicide containing 3.5% Hg2=s methoxyethylmercury-chloride. Final absorption of mercury was approximately 706 to 977 mg, as extrapolated from mercury eliminated in urine. Activated charcoal hemoperfusion removed only 1% to 2% of the amount absorbed. During treatment with D-penicillamine and dimercaprol, which were alternated fortnightly, the mercury elimination half life was 25 days, as calculated from blood concentrations and 23 days as calculated from urine data. Except for local cauterization of the mouth and throat, no signs of liver, kidney or central nervous system intoxication were seen within a 3-month follow-up period.