Acute hyperammonemia and systemic inflammation is associated with increased extracellular brain adenosine in rats : a biosensor study

Acute liver failure (ALF) can lead to brain edema, cerebral hyperperfusion and intracranial hypertension. These complications are thought to be mediated by hyperammonemia and inflammation leading to altered brain metabolism. As increased levels of adenosine degradation products have been found in brain tissue of patients with ALF we investigated whether hyperammonemia could induce adenosine release in brain tissue. Since adenosine is a potent vasodilator and modulator of cerebral metabolism we furthermore studied the effect of adenosine receptor ligands on intracranial pressure (ICP) and cerebral blood flow (CBF). We measured the adenosine concentration with biosensors in rat brain slices exposed to ammonia and in a rat model with hyperammonemia and systemic inflammation. Exposure to ammonia in concentrations from 0.15–10 mM led to increases in the cortical adenosine concentration up to 18 µM in brain slices. In vivo recordings showed a tendency towards increased adenosine levels in rats with hyperammonemia and systemic inflammation compared to a control group (3.7 ± 0.7 vs. 0.8 ± 0.2 µM, P = 0.06). This was associated with a significant increase in ICP and CBF. Intervention with the non-selective adenosine receptor antagonist theophyllamine, the A2A receptor antagonist ZM241385, or the A1 receptor agonist N6-Cyclopentyladenosine did not reduce ICP or CBF. In conclusion, our results show that the adenosine concentration in cortex increases during exposure to ammonia, and is associated with a rise in intracranial pressure and cerebral perfusion. However adenosine receptor antagonism/agonism did not reduce the ICP or CBF which indicates that adenosine may not be of direct importance for these cerebral complications in ALF

Liposomes in dermatology today

Liposomes are vesicles consisting of spherical phospholipid bi-layers with specific properties making them useful for topical application of drugs. Liposome research has expanded considerably over the last 30 years and nowadays, it is possible to construct a wide range of liposomes varying in size, phospholipids composition and surface characteristics to suit the specific application for which they are intended. In dermatology, the topical application of liposomes has proven to be of therapeutic value. Liposomes can be used as carriers for hydrophilic as well as lipophilic therapeutic agents because of their amphipathic character. They may improve stabilization of instable drugs by encapsulating them and serve as penetration enhancers facilitating the transport of compounds that otherwise cannot penetrate the skin. Liposomes help in reducing skin irritation by sustaining the release of drugs and by hydration of the epidermis. They also have the potential to target drugs into the pilosebaceous structures and hence they have an additional advantage for treatment of hair follicle-associated disorders. Clinical data indicate that 5-ALA encapsulated in liposomes improves the quality of Fluorescence Diagnosis by ALA-induced Porphyrins (FD) and optimizes the results of Photodynamic Therapy (PDT). None declared

Treatment of vitiligo with khellin liposomes, ultraviolet light and blister roof transplantation

Background Various surgical and non-surgical methods are available to treat vitiligo. Surgical techniques such as epidermal blister graft transplantation may be effective for the re-pigmentation of stable, but refractory vitiligo areas. Khellin has phototherapeutic properties that are similar to those of the psoralens, but with substantially lower phototoxic effects and DNA mutation effects. Its penetration into the hair follicles is enhanced by encapsulating it into liposomes. Subsequent activation of the khellin with UV light stimulates the melanocytes in the hair follicles. Objective The first objective was to evaluate the additional value of combining blister roof transplantation (BRT) with khellin in liposomes and ultraviolet light (KLUV) in the treatment of recalcitrant vitiligo patches. The second objective was to assess patients' satisfaction. Materials and methods Nineteen patients with vitiligo lesions which did not respond to KLUV treatment for at least a year were treated with BRT followed by KLUV. The transplantation was performed by creating blisters with a suction device, preparing the target site with Erbium laser ablation and the actual transplantation. Locations where randomly assigned. A blinded observer established the results. Results Seventy-five percent of the patients were satisfied with the cosmetic result. All of the patients would recommend the treatment to other vitiligo patients. More than 75% re-pigmentation of the vitiligo areas was noted in 47% of the patients according to the blinded evaluation of photographs taken before and after the treatment