Isolation and intravenous injection of murine bone marrow derived monocytes

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of various fields in biomedical science. The method described below is a simple and effective way to isolate murine monocytes from heterogeneous bone marrow. Bone marrow from the femur and tibia of Balb/c mice is harvested by flushing with phosphate buffered saline (PBS). Cell suspension is supplemented with macrophage-colony stimulating factor (M-CSF) and cultured on ultra-low attachment surfaces to avoid adhesion-triggered differentiation of monocytes. The properties and differentiation of monocytes are characterized at various intervals. Fluorescence activated cell sorting (FACS), with markers like CD11b, CD115, and F4/80, is used for phenotyping. At the end of cultivation, the suspension consists of 45%± 12% monocytes. By removing adhesive macrophages, the purity can be raised up to 86%± 6%. After the isolation, monocytes can be utilized in various ways, and one of the most effective and common methods for in vivo delivery is intravenous tail vein injection. This technique of isolation and application is important for mouse model studies, especially in the fields of inflammation or immunology. Monocytes can also be used therapeutically in mouse disease models.

On-line analysis of nitrogen stable isotopes in NO from ambient air samples

A method was developed for the on-line analysis of nitrogen stable isotopes at the natural abundance level in NO in order to study the NO contribution to the nitrogen cycle in ecosystems and in the atmosphere. The method enables a quick and accurate determination of 15N/14N ratios for NO and consists of the following steps: (a) accumulation of NO from air samples on a molecular sieve of 5 A, (b) desorption of NO from the molecular sieve during 15 min of heating at 350 degrees C (an offset of Deltadelta 4.6% must be corrected for), (c) trapping and cryofocusation of the desorbed NO on a PoraPlot Q matrix at -196 degrees C during heating, (d) release of the trapped NO from the PoraPlot Q matrix followed by chromatographic separation, reduction to N2, and isotopic composition analysis. A minimum sample size of 125 nmol of NO is recommended. A correction function for the calculation of the delta15N-NO values was introduced for sample sizes from 125 to 220 nmol of NO. Measurements of NO in automobile exhaust have proven the applicability of the developed method.