Der Baroreflex: Physiologie, klinische Bedeutung und Diagnostik

Der Baroreflex ist ein Mechanismus zur Aufrechterhaltung der kardiovaskulären Homöostase. Ein Anstieg des Blutdruckes führt, vermittelt durch das vegetative Nervensystem, gegenregulatorisch zu einem Abfall der Herzfrequenz und zu einer Dilatation der Widerstandsgefäße und umgekehrt. Dadurch werden überschießende Blutdruckschwankungen verhindert. Das Ausmaß der Baroreflexantwort ist ein starker und unabhängiger Prädiktor für Überleben und kardiale Ereignisse. Bei Erkrankungen des Herzkreislaufsystems liegt häufig ein pathologisch abgeschwächter Baroreflex vor. Adäquates Therapieansprechen dieser Patienten kann neben einer verbesserten Prognose mit einer Normalisierung der Baroreflexantwort einhergehen. Eine quantitative Beschreibung der Baroreflexantwort auf Blutdruckschwankungen ist die Baroreflexsensitivität (BRS). Es existieren verschiedene Methoden zur Bestimmung der Baroreflexsensitivität. Um die flächendeckende Implementierung dieser Verfahren in der klinischen Routine voranzutreiben, werden in Zukunft eine Optimierung in Bezug auf Messbarkeit und Reliabilität, die Etablierung von Referenzwerten sowie große prospektive Validierungsstudien vonnöten sein.

Biopersistent granular dust and chronic obstructive pulmonary disease: a systematic review and meta-analysis

Objective

Applying a systematic review to identify studies eligible for meta-analysis of the association between occupational exposure to inorganic dust and the development of chronic obstructive pulmonary disease (COPD), and conducting a meta-analysis.

Data Sources

Searches of PubMed and Embase for the time period 1970–2010 yielded 257 cross-sectional and longitudinal studies on people exposed to inorganic dust at the workplace with data on lung function. These studies were independently abstracted and evaluated by two authors; any disagreement was resolved by a third reviewer. Of 55 publications accepted for meta-analysis, 27 investigated the effects of occupational exposure to biopersistent granular dust (bg-dust).

Methods

A random effects meta-analysis allowed us to provide an estimate of the average exposure effect on spirometric parameters presented in forest plots. Between-study heterogeneity was assessed by using I² statistics, with I²>25% indicating significant heterogeneity. Publication bias was investigated by visual inspection of funnel plots. The influence of individual studies was assessed by dropping the respective study before pooling study-specific estimates.

Results

The mean FEV1 of workers exposed to bg-dust was 160 ml lower or 5.7% less than predicted compared to workers with no/low exposure. The risk of an obstructive airway disease—defined as FEV1/FVC < 70%—increased by 7% per 1 mg· m^-3 respirable bg-dust.

Conclusion

Occupational inhalative exposure to bg-dust was associated with a statistically significant decreased FEV1 and FEV1/FVC revealing airway obstruction consistent with COPD.

Vaccination with plasmid DNA activates dendritic cells via Toll-like receptor 9 (TLR9) but functions in TLR9-deficient mice

We analyzed whether the immunobiology of vaccinating plasmid DNA containing a transcription unit for OVA is influenced by immunostimulatory CpG motifs in the plasmid backbone. Indeed, plasmid DNA differentially activated in vitro myeloid and plasmacytoid dendritic cells (DCs) provided they expressed the CpG-DNA receptor, Toll-like receptor 9 (TLR9). Dependent on the DC subset, activation resulted in type 1 IFN production, while both DC subsets produced IL-6 and up-regulated expression of costimulatory molecules CD40 and CD86. In vivo, however, even upon repeated vaccination with plasmid DNA, priming of OVA-specific CTL and clonal expansion of SIINFEKL-specific CD8 T cells were equal in TLR9-positive and TLR9- or MyD88-negative mice. Overall, these results negate a dominant role of CpG-DNA/TLR9 interactions in long-term vaccination protocols.