Mast cells regulate the magnitude and the cytokine microenvironment of the contact hypersensitivity response

The role that mast cells play during contact hypersensitivity (CS) response is unclear because some studies have shown that mast cell-deficient mice have relatively intact CS responses whereas others have shown opposing results. Mast cells secrete a wide range of immunomodulatory mediators and can potentially influence the type of immune response generated in the skin during CS. Therefore, we examined the type of microenvironment generated during CS in both W/Wv mast cell-deficient and wild-type mice in response to different immunizing doses of hapten (oxazolone). The CS response elicited after low-dose oxazolone was significantly diminished in W/Wv mice compared with wild-type mice. Unexpectedly, the CS response elicited in W/Wv mice immunized with high-dose oxazolone was more severe compared with wild-type mice. In addition, after immunization with high-dose oxazolone, the granulocyte infiltrate in W/Wv mice was increased by twofold compared with wild-type mice. A shift in the cytokine milieu toward the expression of type-1 cytokines as well as a significant increase in the local adhesion of neutrophils and CD4 T cells in the microvasculature of the skin was observed after hapten challenge in W/Wv mice immunized with high-dose oxazolone compared with wild-type mice. These results suggest that mast cells can act as regulators and inducers of the inflammatory response depending on immunizing stimulus strength.

Multichannel fluorescence spinning disk microscopy reveals early endogenous CD4 T cell recruitment in contact sensitivity via complement

Contact sensitivity (CS) is one of the primary in vivo models of T cell-mediated inflammation. The presence of CS-initiating CD4 T lymphocytes at the time of challenge is essential for transfer and full development of the late phase CS inflammatory response. From this observation investigators have speculated that early recruitment of CD4 T cells to the site of challenge must occur. Moreover, there must be rapid synthesis/release and disappearance of an important mediator during the first hours after hapten challenge. Using spinning disk confocal microscopy, we observed the very early effector events of the immune response. Simultaneous, real-time visualization of predominant neutrophil and extremely rare CD4 T cell trafficking in the challenged skin vasculature was noted (one rolling CD4 T cell for every 10-18 rolling and adherent neutrophils). We demonstrate that neutrophil adhesion during the early CS response was reduced in C5a receptor-deficient (C5aR-/-) mice or leukotriene B4 receptor antagonist-treated mice, whereas CD4 T cell recruitment was only inhibited in C5aR-/- mice. In line with these observations, leukocyte infiltration and the associated tissue damage were significantly reduced in C5aR-/- mice but not in leukotriene B4 receptor antagonist-treated wild-type mice 24 h after challenge. C5a receptor expression on T cells and not on tissue resident cells was important for the development of a CS response. Thus, by using spinning disk confocal microscopy we visualized the early events of an adaptive immune response and identified the rare but essential recruitment of CD4 T cells via the complement pathway.

Impairment of long-term associative memory in aging snails (Lymnaea stagnalis)

Age-dependent impairment in learning and memory functions occurs in many animal species, including humans. Although cell death contributes to age-related cognitive impairment in pathological forms of aging, learning and memory deficiencies develop with age even without substantial cell death. The molecular and cellular basis of this biological aging process is not well understood but seems to involve a decline in the aging brain's capacity for experience-dependent plasticity. To aid in resolving this issue, we used a simple snail appetitive classical conditioning paradigm in which the underlying molecular, cellular, and neural network functions can be directly linked to age-associated learning and memory performance (i.e., the Lymnaea stagnalis feeding system). Our results indicate that age does not affect the acquisition of appetitive memory but that retention and/or consolidation of long-term memory become progressively impaired with advancing age. The latter phenomenon correlates with declining electrophysiological excitability in key neurons controlling the feeding behavior. Together, these results present the Lymnaea feeding system as a powerful paradigm for investigations of cellular and molecular foundations of biological aging in the brain.

Intravascular device-related infections in critically ill patients

Intravascular device-related infections (IVDRIs) are among the most common nosocomial infections in critically ill patients. Quantitative or semi-quantitative microbiology diagnosis is necessary for their management. Most causative organisms arise from the skin; staphylococci are responsible for two-thirds of the IVDRIs, with Staphylococcus aureus responsible for 5% to 15%. Complications may include septic shock, suppurative thrombophlebitis, and endocarditis. In critically ill patients, intravenous lines are responsible for at least 23% of nosocomial bloodstream infection, which has a mortality of 25% and is associated with a longer stay in intensive care and costs $28,960 per survivor. IVDRIs can be treated with intravenous antibiotics without removing the device, but removal of the catheter is recommended. Prevention is based on careful insertion practice and optimal catheter care. Systemic replacement of the intravenous lines every three to five days is common practice in the USA but not elsewhere in Europe. This issue should be studied, particularly in critically ill patients.

[Results of the modified dacryocystorhinostomie described by Werb (author's transl)]

42 cases operated by the modified Werb's dacryocystorhinostomy with polyethylene tubing are reported. The postoperative follow-up was between 1 and 4 1/2 years. The success rate was 75%. The tube should remain at least 3-4 months. A longer time does not give significantly better results. On 2 unsuccessfully operated persons strong fibrous scar tissue was found during the reoperation at the site of the anastomosis of the tear sack with the nasal mucous membrane. This was probably induced by remaining bone fragments. This simple operative approach can be recommended as a first surgical intervention on patients with a presaccal tear duct stenosis.