Die Bedeutung der histologischen Vorbehandlung bei Untersuchungen der Blut-Hirn-Schranke mit fluorescenzmarkierten Proteinen

Zusammenfassung Die Brauchbarkeit verschiedener histologischer Vorbehandlungsmethoden für Untersuchungen der Blut-Hirn-Schranke mit fluorescenzmarkiertem Gamma-Globulin wurde an Gehirnen normaler Meerschweinchen sowie in der Umgebung einer kortikalen Kältenekrose am Katzenhirn untersucht. Neben der Gefriertrocknung erwies sich die Methode der Freeze Substitution am Kryostatschnitt (Chang und Hori, 1961) als sehr zuverlässig. Es wurde darauf hingewiesen, daß einfache Formolfixierung der entnommenen Gewebsblöcke nur dann zuverlässige Resultate liefert, wenn diese entsprechend klein sind, so daß eine schnelle Durchfixierung gewährleistet ist. Als unbrauchbar erwiesen sich die Alkoholfixierung sowie die Nachfixierung von Kryostatschnitten in Alkohol oder Formol.

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Summary The usefulness of several histological methods for studying the blood-brain-barrier by fluorescent labelled gamma globulin was compared. Brain tissue from normal guinea pigs and from a cat subjected to cortical cold injury were used in this study. The best results were obtained with the freezing and drying technique and the section freeze substitution method of Chang and Hori (1961). Simple formalin fixation produced artefacts when the tissue blocks were too big for a fast fixation. Alcohol and mounted cryostat section fixation gave unsatisfactory results.

     

Separation of bacteria smaller than 4 µm from other blood components using insulator-based dielectrophoresis: numerical simulation approach

Biomechanics and Modeling in Mechanobiology - Bloodstream infection (BSI) is a life-threatening infection that causes more than 80,000 deaths and more than 500,000 infections annually in North...     

Relationships between environmental variables and vegetation across mountain wetland sites,N. Iran

The mountain wetlands studied represent a unique habitat on the southern slopes of the Alborz mountain range, the second largest range in Iran. In comparison with other parts of this range the western section is ecologically and botanically unknown. Floristic and vegetation variation were assessed using diverse environmental variables along a broad altitudinal span (350 m to 3200 m a.s.l.). Using both statistical and ordination analyses floristic variation was assessed on three defined altitudinal belts which were delimited based on Alborz macro-climatic boundaries. The distribution of individual wetland plant species, of phytogeographic elements and of life-forms all differ among altitudinal belts. This result is also shown in both direct and indirect analyses of ordinations. The proportion of geophytes significantly increases with altitude and geophytes are very well represented in the upper altitudinal belt. The number of species of a narrow phytogeographical distribution (e.g. endemics) increases with altitude, soil pH and EC declined with altitude. The first axis of DCA ordination with passively projected environmental variables indicates that, organic matter and concentration of Fe²⁺ are increased toward higher altitude. The second axis of ordination is related to both soil texture and slope inclination. The distribution of species in the CCA species plot is also close to the distribution of those in the DCA ordination. This study indicates that altitude and slope together with other dependent environmental variables (pH, EC, Ca²⁺ and soil texture) are the main ecological factors controlling species distribution across the Western Alborz wetland sites.     

Rheumatoid factor,not antibodies against citrullinated proteins,is associated with baseline disease activity in rheumatoid arthritis clinical trials

IntroductionAlthough the prognostic value of rheumatoid factor (RF) and autoantibodies against citrullinated proteins (ACPAs) in patients with rheumatoid arthritis (RA) is well established, their association with RA disease activity remains unclear. Here, we investigate this association in a large study using data from clinical trials.MethodsWe used baseline data from four recent randomized controlled clinical trials of RA. We investigated individual and composite measures of disease activity. The relationship of RF and ACPAs with these measures was investigated by using stratified analysis (comparing four groups of patients according to the presence or absence of RF and ACPAs) and matched analysis (disease activity levels compared between patients negative and patients highly positive for one autoantibody who were matched for levels of the other autoantibody as well as for age, gender, and duration of RA).ResultsA total of 2118 patients were analysed in the different cohorts. In the stratified analysis, RF⁺ patients, regardless of ACPA status, had the highest levels of disease activity, whereas ACPA⁺ patients had disease activity that was similar to or lower than that of ACPA⁻ patients, both in the presence and in the absence of RF. When matched for ACPA levels, patients with highly positive RF had significantly higher disease activity for all composite indices compared with patients who were RF⁻ (P = 0.0067), whereas ACPA-highly-positive and ACPA-negative patients matched for RF levels had similar disease activity, again even with the tendency toward lower disease activity for ACPA⁺ patients (P = 0.054).ConclusionThe data presented suggest that the presence of RF has a clear association with higher levels of disease activity but that the presence of ACPAs has not and even appears to be associated with lower disease activity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0736-9) contains supplementary material, which is available to authorized users.