Biomedical subjects

Birgit Kraft

Publications and source records attributed to Birgit Kraft.

5 recordsLinked to original sources

PubMed2005

Indirect CB2 receptor and mediator-dependent stimulation of human whole-blood neutrophils by exogenous and endogenous cannabinoids.

Immunomodulatory effects of endogenous and exogenous cannabinoids have been investigated in numerous studies, mostly performed with isolated cells or transformed cell lines, but only sparse data exist on human polymorphonuclear neutrophils (PMNs). We therefore investigated the respiratory burst reaction of human whole-blood PMNs under the influence of cannabinoids using flow cytometry. In their natural whole-blood milieu, a CB(2) receptor-dependent stimulation of the PMN respiratory burst was found at nanomolar concentrations of CP55 940 [(-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol] and methanandamide after a 3-h incubation period, whereas the short-living and rapidly hydrolyzed endogenous ligand anandamide did not alter the burst reaction of whole-blood PMNs under the same experimental conditions. The stimulatory cannabinoid effect was totally absent in isolated PMNs but could be transferred onto isolated PMNs by adding the cell-free low-molecular mass plasma fraction (<5000 Da) of cannabinoid-incubated blood, indicating an indirect mechanism depending on humoral products or mediators. Results of our further experiments suggest that products of the arachidonic acid metabolism are mediators of the cannabinoid-induced enhancement of the respiratory burst reaction of whole-blood PMNs.

Arachidonic Acids↗

PubMed2005

Opioid medication and driving ability.

In many European countries the use of opioids for long-term treatment of nonmalignant pain has dramatically increased during the last decade in order to improve the patient's quality of life, to allow an active social life and the return to work. In modern society, driving is regarded as an essential activity of daily living. Since opioids are centrally acting drugs that may interfere with the ability of safely driving a motor vehicle, the question arises of whether or not and on which conditions patients under continuous opioid medication may be considered fit to drive. In this article the evidence from recent studies of opioid effects on driving ability of patients is reviewed. Based on these data, the prerequisites and restrictions for driving under chronic opioid medication are outlined and practical guidelines are proposed.

Analgesics, Opioid↗

PubMed2004

Cannabinoid receptor-independent suppression of the superoxide generation of human neutrophils (PMN) by CP55 940, but not by anandamide.

Cannabinoids have been shown to affect various immune functions. To date, almost no data exist on PMN, which provide the first line antimicrobial defense. The objective of the present study was to investigate the effects of the synthetic dibenzopyrane ligand CP55 940, the endogenous cannabinoid anandamide and methanandamide on the "respiratory burst" of isolated human PMN in vitro. After preincubation with high micromolar concentrations of CP55 940, fMLP-stimulated PMN showed a reduction in superoxide production, whereas the spontaneous burst activity of resting PMN remained unaffected. This inhibitory effect of CP55 940 was not CB-receptor-mediated. In contrast, anandamide and methanandamide did not alter the oxidative microbicidal PMN function.

Adult↗

PubMed2004

The procoagulatory effects of delta-9-tetrahydrocannabinol in human platelets.

Delta-9-tetrahydrocannabinol (THC) is increasingly used for the long-term treatment of nausea, vomiting, cachexia, and chronic pain. Recent reports, however, have indicated an increased risk of myocardial infarction and thromboangiitis obliterans after THC intake. Blood platelets have an essential role in the pathogenesis of these two diseases, but it is unclear whether platelets are potential target cells for cannabinoids. We investigated the effects of THC on human platelets and the expression of cannabinoid receptors on their cell membranes in this in vitro study. The effects of THC (final concentrations 10(-7) to 10(-5) M) on the expression of activated platelet fibrinogen receptor (glycoprotein IIb-IIIa) and P selectin were characterized by flow cytometry. Western blotting was performed with platelet membrane preparations to determine the surface expression of cannabinoid receptors on human platelets. THC increased the expression of glycoprotein IIb-IIIa and P selectin on human platelets in a concentration-dependent manner. The two known cannabinoid receptors (CB(1) and CB(2)) were both detected on the cell membrane of human platelets. Our functional results may suggest a receptor-dependent pathway of THC-induced platelet activation. However, further in vivo studies are warranted to evaluate the role of cannabinoid receptors in mediating the demonstrated procoagulatory effect of THC.

Blood Coagulation↗

PubMed2003

No evidence for direct modulatory effects of delta 9-tetrahydrocannabinol on human polymorphonuclear leukocytes.

The effects of cannabinoids (CB) that have been reported in various leukocyte populations were mainly immunosuppressive or immunomodulatory. Almost nothing is known, however, about direct interactions of cannabinoids with human polymorphonuclear cells (PMN), although m-RNA for the cannabinoid receptor-2 (CB(2)) was found in human PMN. In order to investigate a potential influence of cannabinoids on human PMN, the migration and phagocytosis of PMN were studied in the presence of Delta(9)-Tetrahydrocannabinol (Delta(9)-THC) at final concentrations between 10(-10) and 10(-5) M. No effect was detectable on these essential PMN functions; and besides, no CB(2)-receptor expression could be detected using the Western blotting technique. Thus, circulating human PMN from healthy individuals remain unaffected by Delta(9)-THC due to the absence of functional CB(2)-receptor expression.

Adjuvants, Immunologic↗