Personalized medicine can pave the way for the safe use of CB₁ receptor antagonists

Antagonists of cannabinoid type-1 (CB?) receptors have been explored as therapeutic agents for obesity and addiction. However, use of rimonabant (the first marketed CB? receptor antagonist) has been suspended due to its anxiogenic and depressive side effects (including suicide risk). Recent genomic studies provide evidence that variants of the CB? receptor gene (CNR1) alone or in combination with the gene of the serotonin transporter (SLC6A4) contribute to the development of anxiety and/or depression, suggesting that high-risk individuals could be identified through genetic testing. In this review, we argue that identification of high-risk individuals by a combination of genomic screening, previous risk phenotype, and environmental risk factors offers a promising method for the safe use of centrally acting CB? receptor antagonists. We summarize endocannabinoid signaling in pathways related to anxiety and depression, identify the serotonergic system as the most likely candidate to mediate the side effects of CB? receptor antagonists, and propose that poloymorphisms in CNR1, SLC6A4 and certain CYP 450 enzymes could help to identify individuals who may benefit from treatment with CB? receptor antagonist without psychiatric side effects.     

Epstein‐Barr virus‐encoded EBNA‐5 forms trimolecular protein complexes with MDM2 and p53 and inhibits the transactivating function of p53

We report that MDM2, a negative regulator of p53, can bind to EBNA‐5. Using GST pull‐down assay, immunoprecipitation, surface plasmon resonance and immunostaining of lymphoblastoid cells, we found that trimolecular complexes are formed between EBNA‐5, MDM2 and p53, where MDM2 serves as a bridge. The EBNA‐5 binding to MDM2 counteracted destabilizing effect of the latter on the p53. In ubiquitination and degradation assays in vitro, EBNA‐5 inhibited p53 polyubiquitination (but not monoubiquitination) in a concentration‐dependent manner. This resembles the effect of p14ARF on p53. Moreover, EBNA‐5 was found to inhibit the degradation of p53 in vitro. High levels of p53 expression were maintained in LCLs. The binding of EBNA‐5 to MDM2 also could impair the functional activity of p53. The p53‐dependent genes P21 and VDR were not induced in EBV‐infected, in contrast to mitogen‐activated cells. This may explain the tolerance of established LCLs to high levels of p53 without undergoing apoptosis.     

International registry on factor XIII deficiency: a basis formed mostly on European data

FXIII deficiency is known as one of the rarest blood coagulation disorders. In this study, the phenotypic and in part genotypic data of 104 FXIII-deficient patients recorded from 1993 - 2005 are presented. The most common bleeding symptoms were subcutaneous bleeding (57%) followed by delayed umbilical cord bleeding (56%), muscle hematoma (49%), hemorrhage after surgery (40%), hemarthrosis (36%), and intracerebral bleeding (34%). Prophylactic treatment was initiated in about 70% of all patients. FXIII-B subunit-deficient patients had a milder phenotype than patients with FXIII-A subunit deficiency. The most frequent mutation affecting the F13A gene was a splice site mutation in intron 5 (IVS5-1G>A). This mutation was found in eight (17%) of 46 analyzed families. The haplotype analysis of patients carrying the IVS5-1A allele was consistent with a founder effect. The international registry (http://www.f13-database.de) will provide clinicians and scientists working on FXIII deficiency with a helpful tool to improve patient care and direct future studies towards better understanding and treatment of the disease.     

Stimulation of H(2)O(2) generation by calcium in brain mitochondria respiring on alpha-glycerophosphate

It has been reported recently (Tretter et al., 2007b) that in isolated guinea pig brain mitochondria supported by alpha-glycerophosphate (alpha-GP) reactive oxygen species (ROS) are produced through the reverse electron transport (RET) in the respiratory chain and by alpha-glycerophosphate dehydrogenase (alpha-GPDH). We studied the effect of calcium on the generation of H(2)O(2) as measured by the Amplex Red fluorescent assay in this model. H(2)O(2) production in alpha-GP-supported mitochondria was increased significantly in the presence of 100, 250, and 500 nM Ca(2+), respectively. In addition, Ca(2+) enhanced the membrane potential, the rate of oxygen consumption, and the NAD(P)H autofluorescence in these mitochondria. Direct measurement of alpha-GPDH activity showed that Ca(2+) stimulated the enzyme by decreasing the Km for alpha-GP. In those mitochondria where RET was eliminated by the Complex I inhibitor rotenone (2 microM) or due to depolarization by ADP (1 mM), the rate of H(2)O(2) formation was smaller and the stimulation of H(2)O(2) generation by Ca(2+) was prevented partly, but the stimulatory effect of Ca(2+) was still significant. These data indicate that in alpha-GP-supported mitochondria activation of alpha-GPDH by Ca(2+) leads to an accelerated RET-mediated ROS generation as well as to a stimulated ROS production by alpha-GPDH.     

Clinical efficacy of a single afternoon dose of effervescent levodopa-carbidopa preparation (CHF 1512) in fluctuating Parkinson disease

A possible cause of motor fluctuations in patients with Parkinson disease is the erratic drug absorption. In a randomized double-blind double-dummy study of melevodopa (levodopa methyl ester), a highly soluble levodopa pro-drug plus carbidopa (CHF 1512) was compared to a standard formulation of levodopa/carbidopa (LD/CD) in 74 fluctuating Parkinson disease patients. The first afternoon, LD/CD tablet was substituted with an equimolar dose of CHF 1512. The study lasted 4 weeks and was followed by an 8-week (optional) open phase. The primary efficacy variable was latency to "on." Patients randomized to receive CHF 1512 had a significative shorter latency to "on" than those randomized to LD/CD and a similar "on" duration. The safety profile of CHF 1512 was also comparable with LD/CD.     

ATP-binding cassette transporter ABCG2 (BCRP) and ABCB1 (MDR1) variants are not associated with disease susceptibility, disease phenotype response to medical therapy or need for surgeryin Hungarian patients with inflammatory bowel diseases

OBJECTIVE: MDR1 (ABCB1), a member of the ATP-binding cassette (ABC) transporters, is an attractive candidate gene for the pathogenesis of inflammatory bowel diseases (IBD) and perhaps for response to therapy. Since limited data are available on MDR1 and ABCG2 polymorphisms in East European IBD patients, the aim of this study was to investigate ABCG2 and MDR1 variants and responses to medical therapy and/or disease phenotype in Hungarian patients. MATERIAL AND METHODS: A total of 414 unrelated IBD patients (Crohn's disease (CD): 265, age: 35.2+/-12.1 years, duration: 8.7+/-7.6 years and ulcerative colitis (UC): 149, age: 44.4+/-15.4 years, duration: 10.7+/-8.9 years) and 149 healthy subjects were investigated. ABCG2 G34A, C421A and MDR1 C3435T, G2677T/A single nucleotide polymorphisms (SNPs) were detected using real-time polymerase chain reaction (PCR). Detailed clinical phenotypes were determined by reviewing the medical charts. RESULTS: The frequency of the ABCG2 and MDR1 SNPs was not significantly different among IBD, CD, UC patients and controls. There was no difference in risk for steroid resistance in CD patients carrying variant ABCG2 (19.6% versus non-carriers 18.4%, p=NS) or MDR1 3435T (CC: 22.2% versus CT/TT: 17.6%) alleles. In addition, carriage of the variant allele was not associated with disease phenotype, presence of extra-intestinal manifestations, smoking, response to infliximab therapy or the need for surgery. In UC, the carriage of variant ABCG2 alleles seemed to be preventive for arthritis (15.5% versus 31.7%, OR: 0.39, 95% CI: 0.16-0.98). CONCLUSIONS: MDR1 and ABCG2 SNPs were not associated with disease susceptibility or disease phenotype in Hungarian patients, and variant alleles did not predict the response to medical therapy or the need for surgery. Further studies are needed to clarify the association between the presence of ABCG2 variants and arthritis in UC.     

Investigation of the Effects of PACAP on the Composition of Tear and Endolymph Proteins

Pituitary adenylate cyclase activating polypeptide (PACAP) is widely distributed in ocular tissues, including the lacrimal gland. PACAP has been shown to influence the activity of several exocrine glands, but its effects on the composition of the tear film are not known yet. Similarly, the presence of PACAP has already been shown in the inner ear, but it is not known whether PACAP influences the composition of the endolymph. The aim of the present study was to investigate whether systemic injection of PACAP has any modulatory effects on the protein composition of the tear film and endolymph using chip electrophoresis and mass spectrometry analysis. Tear and endolymph samples were collected from rats and chickens, respectively, at various time points after systemic injection of PACAP. Fluid samples were further processed for chip electrophoretic studies. No difference was found in the protein composition of the endolymph between control and PACAP-treated animals. In contrast, tear samples showed a marked difference after PACAP treatment. Proteins in the molecular range 50-70 kDa, which showed a different chip electropherogram profile in every PACAP-treated sample, were further analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. PACAP treatment induced a repression in certain keratins, while others were induced after PACAP injection. Furthermore, PACAP treatment decreased aldehyde dehydrogenase expression. The present study provides a base for further studies on the in vivo effects of PACAP on the composition of tear film. These investigations may have important clinical relevance because of the noninvasive sample collection, the correlation between tear proteins and ocular diseases, and the possible presence of biomarkers for both ophthalmological and systemic pathological conditions.