High frequency and founder effect of the CYP3A4*20 loss-of-function allele in the Spanish population classifies CYP3A4 as a polymorphic enzyme.

Cytochrome P450 3A4 (CYP3A4) is a key drug-metabolizing enzyme. Loss-of-function variants have been reported as rare events, and the first demonstration of a CYP3A4 protein lacking functional activity is caused by CYP3A4*20 allele. Here we characterized the world distribution and origin of CYP3A4*20 mutation. CYP3A4*20 was determined in more than 4000 individuals representing different populations, and haplotype analysis was performed using CYP3A polymorphisms and microsatellite markers. CYP3A4*20 allele was present in 1.2% of the Spanish population (up to 3.8% in specific regions), and all CYP3A4*20 carriers had a common haplotype. This is compatible with a Spanish founder effect and classifies CYP3A4 as a polymorphic enzyme. This constitutes the first description of a CYP3A4 loss-of-function variant with high frequency in a population. CYP3A4*20 results together with the key role of CYP3A4 in drug metabolism support screening for rare CYP3A4 functional alleles among subjects with adverse drug events in certain populations.

Polymorphisms in cytochromes P450 2C8 and 3A5 are associated with paclitaxel neurotoxicity.

Neurotoxicity is one of the most relevant dose-limiting toxicities of the anticancer drug paclitaxel. It exhibits substantial interindividual variability of unknown molecular basis, and represents one of the major challenges for the improvement of paclitaxel therapy. The extensive variability in paclitaxel clearance and metabolism lead us to investigate the association between polymorphisms in paclitaxel elimination pathway and neurotoxicity. We selected 13 relevant polymorphisms in genes encoding paclitaxel metabolizing enzymes (CYP2C8, CYP3A4 and CYP3A5) and transporters (organic anion transporting polypeptide (OATP) 1B1, OATP1B3 and P-glycoprotein) and genotyped them in 118 Spanish cancer patients treated with paclitaxel. After adjusting for age and treatment schedule, CYP2C8 Haplotype C and CYP3A5*3 were associated with protection (hazard ratio (HR) (per allele)=0.55; 95% confidence interval (CI)=0.34-0.89; P=0.014 and HR (per allele)=0.51; 95%CI=0.30-0.86; and P=0.012, respectively) and CYP2C8*3 with increased risk (HR (per allele)=1.72; 95%CI=1.05-2.82; and P=0.032). In each case, the allele causing increased paclitaxel metabolism was associated with increased neurotoxicity, suggesting an important role for metabolism and hydroxylated paclitaxel metabolites. We estimated the HR per paclitaxel-metabolism increasing allele carried across the three polymorphisms to be HR=1.64 (95% CI=1.26-2.14; P=0.0003). The results for P-glycoprotein were inconclusive, and no associations were observed for the other genes studied. The incorporation of this genetic data in treatment selection could help to reduce neurotoxicity events, thereby individualizing paclitaxel pharmacotherapy. These results warrant validation in independent series.

Rationalization of genetic testing in patients with apparently sporadic pheochromocytoma/paraganglioma.

Hereditary susceptibility to pheochromocytoma (PCC) and paraganglioma (PGL) represents a very complex genetic scenario. It has been reported that the absence of familial antecedents of the disease does not preclude the existence of a mutation affecting any of the five major susceptibility genes. In fact, 11-24% of apparently sporadic cases (without familial or syndromic antecedents) harbor an unexpected germline mutation, but we do not know what is happening in "truly apparently" sporadic patients (i.e., apparently sporadic cases diagnosed with only one tumor). In the present study, we have analyzed 135 apparently sporadic patients developing a single tumor for the five major susceptibility genes: VHL, RET, SDHB, SDHC, and SDHD. Fourteen percent of cases were found to harbor a germline mutation, and only 2.2% of patients were older than 45 years at onset. By taking into account the tumor location and a threshold age at onset of 45 years, we propose a rational scheme for genetic testing. Analyzing VHL and RET genes would be recommended only in young patients developing a single PCC. On the other hand, genetic testing of SDHD should be done in all patients developing an extra-adrenal tumor before the age of 45, and SDHC could be the responsible gene in cases developing a single head and neck tumor, independently of age. Finally, the analysis of SDHB should always be performed because of its association to malignancy and the low penetrance of mutations affecting this gene.

Cellular senescence bypass screen identifies new putative tumor suppressor genes.

Senescence is a mechanism that limits cellular lifespan and constitutes a barrier against cellular immortalization. To identify new senescence regulatory genes that might play a role in tumorigenesis, we have designed and performed a large-scale antisense-based genetic screen in primary mouse embryo fibroblasts (MEFs). Out of this screen, we have identified five different genes through which loss of function partially bypasses senescence. These genes belong to very different biochemical families: csn2 (component of the Cop9 signalosome), aldose reductase (a metabolic enzyme) and brf1 (subunit of the RNA polymerase II complex), S-adenosyl homocysteine hydrolase and Bub1. Inactivation, at least partial, of these genes confers resistance to both p53- and p16INK4a-induced proliferation arrest. Furthermore, such inactivation inhibits p53 but not E2F1 transcriptional activity and impairs DNA-damage-induced transcription of p21. Since the aim of the screen was to identify new regulators of tumorigenesis, we have tested their inactivation in human tumors. We have found, either by northern blot or quantitative reverse transcriptase-PCR analysis, that the expression of three genes, Csn2, Aldose reductase and Brf1, is lost at different ratios in tumors of different origins. These genes are located at common positions of loss of heterogeneity (15q21.2, 7q35 and 14q32.33); therefore,we have measured genomic losses of these specific genes in different tumors. We have found that Csn2 and Brf1 also show genomic losses of one allele in different tumors. Our data suggest that the three genes identified in the genome-wide loss-of-function genetic screen are putative tumor suppressors located at 15q21.2; 7q35 and 14q32.33.

Molecular characterisation of a common SDHB deletion in paraganglioma patients.

BACKGROUND: Hereditary susceptibility to familial paraganglioma syndromes is mainly due to mutations in one of six genes, including three of the four genes encoding the subunits of the mitochondrial succinate dehydrogenase complex II. Although prevalence, penetrance and clinical characteristics of patients carrying point mutations affecting the genes encoding succinate dehydrogenase have been well studied, little is known regarding these clinical features in patients with gross deletions. Recently, we found two unrelated Spanish families carrying the previously reported SDHB exon 1 deletion, and suggested that this chromosomal region could be a hotspot deletion area. METHODS: We present the molecular characterisation of this apparently prevalent mutation in three new families, and discuss whether this recurrent mutation is due either to the presence of a founder effect or to a hotspot. RESULTS: The breakpoint analysis showed that all Iberian Peninsular families described harbour the same exon 1 deletion, and that a different breakpoint junction segregates in an affected French pedigree. CONCLUSIONS: After haplotyping the SDHB region, we concluded that the deletion detected in Iberian Peninsular people is probably due to a founder effect. Regarding the clinical characteristics of patients with this alteration, it seems that the presence of gross deletions rather than point mutations is more likely related to abdominal presentations and younger age at onset. Moreover, we found for the first time a patient with neuroblastoma and a germline SDHB deletion, but it seems that this paediatric neoplasia in a pheochromocytoma family is not a key component of this disease.

Cytochrome P450 3A5 is highly expressed in normal prostate cells but absent in prostate cancer.

Testosterone is essential for the growth and function of the luminal prostate cells, but it is also critical for the development of prostate cancer, which in the majority of the cases derives from luminal cells. Cytochrome P450 3A (CYP3A) enzymes hydroxylate testosterone and dehydroepiandrosterone to less active metabolites, which might be the basis for the association between CYP3A polymorphisms and prostate cancer. However, it is unknown whether the CYP3A enzymes are expressed at relevant levels in the prostate and which polymorphisms could affect this tissue-specific CYP3A activity. Thus, we measured CYP3A4, CYP3A5, CYP3A7, and CYP3A43 mRNA in 14 benign prostatic hyperplasias and ten matched non-tumoral/tumoral prostate samples. We found that CYP3A5 mRNA in non-tumoral prostate tissue was 10% of the average amount of liver samples, whereas the expression of the other CYP3A genes was much lower. Similarly to liver, CYP3A5*3 polymorphism decreased CYP3A5 mRNA content 13-fold. CYP3A5 protein was detected in non-tumoral prostate microsomes by western blot, and immunohistochemistry (IHC) localized CYP3A5 exclusively in the basolateral prostate cells. In contrast to the normal tissue, IHC and RT-PCR showed that tumoral tissue lacked CYP3A5 expression. In conclusion, prostate basolateral cells express high levels of CYP3A5 which dramatically decrease in tumoral tissue. This finding supports an endogenous function of CYP3A5 related to the metabolism of intra-prostatic androgens and cell growth, and that polymorphisms affecting CYP3A5 activity may result in altered prostate cancer risk and aggressiveness.

Epigenetic analysis of HIC1, CASP8, FLIP, TSP1, DCR1, DCR2, DR4, DR5, KvDMR1, H19 and preferential 11p15.5 maternal-allele loss in von Hippel-Lindau and sporadic phaeochromocytomas.

Phaeochromocytoma is a neural-crest-derived tumour that may be a feature of several familial cancer syndromes including von Hippel-Lindau (VHL) disease, multiple endocrine neoplasia type 2 (MEN 2), neurofibromatosis type 1 (NF1) and germline succinate dehydrogenase subunit (SDHB and SDHD) mutations. However the somatic genetic and epigenetic events that occur in phaeochromocytoma tumourigenesis are not well defined. Epigenetic events including de novo promoter methylation of tumour-suppressor genes are frequent in many human neoplasms. As neuroblastoma and phaeochromocytoma are both neural-crest-derived tumours, we postulated that some epigenetic events might be implicated in both tumour types and wished to establish how somatic epigenetic alterations compared in VHL-associated and sporadic phaeochromocytomas. We identified frequent aberrant methylation of HIC1 (82%) and CASP8 (31%) in phaeochromocytoma, but both genes were significantly more methylated in VHL phaeochromocytomas than in sporadic cases. Of four tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors analysed, DR4 was most commonly methylated (41%; compared with DcR2 (26%), DcR1 (23%) and DR5 (10%)). Gene methylation patterns in phaeochromocytoma and neuroblastoma did not differ significantly suggesting overlapping mechanisms of tumourigenesis. We also investigated the role of 11p15.5-imprinted genes in phaeochromocytoma. We found that in 10 sporadic and VHL phaeochromocytomas with 11p15.5 allele loss, the patterns of methylation of 11p15.5-differentially methylated regions were consistent with maternal, rather than, paternal chromosome loss in all cases (P<0.001). This suggests that 11p15.5-imprinted genes may be implicated in the pathogenesis of both familial (germline VHL and SDHD mutations) and sporadic phaeochromocytomas.

Long term improvement in the treatment of canine leishmaniosis using an antimony liposomal formulation.

Pharmacokinetic and clinical effectiveness of liposome-encapsulated N-methylglucamine antimoniate (LMA) was performed in dogs suffering from experimental leishmaniosis. LMA was compared with N-methylglucamine antimoniate (MGA), the same drug in its free form. Sb plasma concentrations for LMA were always higher than those for MGA. Mean residence time (MRT), half-life time (t(1/2)) and clearance (Cl) showed that Sb was eliminated slower after liposome administration. The high volume of distribution (Vd) obtained with LMA suggests that Sb could achieve therapeutic concentrations in parasite-infected tissues. Average plasma concentration at steady state (Css(ave)) shows that Sb body concentrations after LMA treatment (9.8 mg/kg Sb, each 24h) would be effective in Leishmania infantum canine infection. Comparing LMA with MGA in a 1-year follow-up we observed no relapses for LMA and total protein and gammaglobulin concentrations were within normal range, while for MGA both began to rise 3 months after treatment. Use of antimonial liposomal formulations may restore effectiveness to an existing drug and reduce toxicity.

A major secreted elastase is essential for pathogenicity of Aeromonas hydrophila.

Aeromonas hydrophila is an opportunistic pathogen and the leading cause of fatal hemorrhagic septicemia in rainbow trout. A gene encoding an elastolytic activity, ahyB, was cloned from Aeromonas hydrophila AG2 into pUC18 and expressed in Escherichia coli and in the nonproteolytic species Aeromonas salmonicida subsp. masoucida. Nucleotide sequence analysis of the ahyB gene revealed an open reading frame of 1,764 nucleotides with coding capacity for a 588-amino-acid protein with a molecular weight of 62,728. The first 13 N-terminal amino acids of the purified protease completely match those deduced from DNA sequence starting at AAG (Lys-184). This finding indicated that AhyB is synthesized as a preproprotein with a 19-amino-acid signal peptide, a 164-amino-acid N-terminal propeptide, and a 405-amino-acid intermediate which is further processed into a mature protease and a C-terminal propeptide. The protease hydrolyzed casein and elastin and showed a high sequence similarity to other metalloproteases, especially with the mature form of the Pseudomonas aeruginosa elastase (52% identity), Helicobacter pylori zinc metalloprotease (61% identity), or proteases from several species of Vibrio (52 to 53% identity). The gene ahyB was insertionally inactivated, and the construct was used to create an isogenic ahyB mutant of A. hydrophila. These first reports of a defined mutation in an extracellular protease of A. hydrophila demonstrate an important role in pathogenesis.

Acute biliary pancreatitis: sphincter of Oddi and choledochal pressure.

Twenty four patients with biliary pancreatitis were divided into three groups: A (18 subjects underwent surgery on the biliary tract seven days after admission to hospital when acute signs disappeared); B (3 cases were operated two months later), and C (3 patients underwent emergency surgery for acute cholescistitis with simultaneous acute pancreatitis). A cholecistectomy-choledochostomy through a Kehr tube was performed in all patients. Pressure in the main biliary duct (MBD) was measured. Only group A was significant (18 cases). As a control, another group, group D was considered (52 biliary cholecysto-choledochal lithiasis patients without pancreatitis and without transduodenal sphincterotomy). Group A: 1) The mean pressure in MBD on the fourth postoperative day (11 days after onset of pancreatitis) was low (p < 0.0001) in relation to that of group D with Oddi's sphincter (SO) normal; 2) in group A, no significant differences (p-NS) were found in relation to positions: during fasting, 4.4 +/- 4 cm H2O in the upright position, and 5.3 +/- 2 when lying (in group D, 9.9 +/- 4.1 cm H2O upright, and 7.76 +/- 3.6 lying with p = 0.0001), and 3) a slow improvement of pressure was observed and, on the 25th day after operation, it was nearly normal (9 cm H2O upright and 7 cm lying with p < 0.001). Group B: biliary surgery at 2 months; mean pressure in MBD meartly normal. Group C: 1) 4 days after emergency surgery, the pressure in MBF (15 cm H2O upright and 11.7 lying) was higher than in subjects with normal SO, probably due to compression of the distal part of MBD by the inflamed pancreas, and 2) from the 11th day the pressure followed the same evolution as that of group A. In conclusion, in patients with acute biliary pancreatitis, operated on the biliary tract when acute signs disappeared, MBD pressure is low (p < 0.0001) in reference to normal on the fourth post-operatory day (11 days after onset of pancreatitis) and no significant differences were found in relation to positions (upright and lying). The pressure changes are transient (4-5 weeks) and most probably due to the lesions and malfunction of the SO related to pancreatitis.

[Cholelithiasis. Post-choledochostomy intraductal pressure (without and with sphinctero-infundibulostomy]. / Colelitiasis. Presiones intraductales poscoledocotomía (sin y con esfinteroinfundibulotomía).

In 72 patients operated on for lithiasis of the main biliary duct (MBD), the intraductal pressure was measured through the choledochostomy T-tube. This measure was done, both in upright and lying positions, fasting and after lunch. Two groups were considered: A (of 52 cases) and B (of 20 cases). In both groups a choledochotomy was performed, and only in group B a long, although partial, sphincterotomy was also done. Three patients in group B had the upper part of the sphincter of Oddi (SO) dilated by big stones. 1) When groups A and B were compared, no significant differences of pressures in MBD was found. 2) Highly significant differences (p = 0.0001) were always found when paired data related to positions were compared: in the upright position pressures in MBD were higher than on the lying position. Group A, during fasting (9.90 +/- 4.1 cm H2O, in upon position, and 7.76 +/- 3.6 when lying) and group B, also at fasting (8.95 +/- 3.0 in the upright position and 6.57 +/- 3.0, when lying). The three patients included in group B with big stones impacted in the upper part of SO, showed low pressures in MBD, specially one (2 and 1 cm H2O, upright lying positions), but the group is too small have statistical significance. We conclude that the long but partial sphincterotomy does not modify significantly the pressures in MBD whether upright or lying, and when paired data related to positions were compared, upright pressures were always higher than on the lying position (p = 0.0001).

Identification of Aeromonas hydrophila hybridization group 1 by PCR assays.

Synthetic oligonucleotide primers of 24 and 23 bases were used in a PCR assay to amplify a sequence of the lip gene, which encodes a thermostable extracellular lipase of Aeromonas hydrophila. A DNA fragment of approximately 760 bp was amplified from both sources, i.e., lysed A. hydrophila cells and isolated DNA. The amplified sequence was detected in ethidium bromide-stained agarose gels or by Southern blot analysis with an internal HindIII-BamHI 356-bp fragment as a hybridization probe. With A. hydrophila cells, the sensitivity of the PCR assay was < 10 CFU, and with the isolated target, the lower detection limit was 0.89 pg of DNA. Primer specificity for A. hydrophila was determined by the PCR assay with cells of 50 strains of bacteria, including most of the 14 currently recognized DNA hybridization groups of Aeromonas spp. as well as other human and environmental Aeromonas isolates. Detection of A. hydrophila by PCR amplification of DNA has great potential for rapid identification of this bacterium because it has proved to be highly specific.

[Somatostatin and choleresis in human beings during the digestive phase]. / Somatostatina y coleresis en el ser humano durante la fase digestiva.

The effect of somatostatin on human choleresis has been poorly studied. Nearly all present knowledge comes from animal research (dog). In the human being, the effect is known in fasted patients. But no data are available of its action during digestion. In the present study, before removing the choledochostomy T-tube from 73 patients operated on for biliary disease, the bile output (40% of the total choleresis) was measured for 4 hours, at 30 min intervals: during fasting, lunch and after lunch: 1) at fasting (A) 10.5 +/- 2.2 cc; at lunch (B) 18.6 +/- 5.4 cc, and after lunch (C) 16.8 +/- 4.5 cc. These differences were highly significant: A vs B p < 0.0001, and A vs C p < 0.0001. In a second part, 10 of these patients received subcutaneously 0.1 mg of SMS 201-995 (a somatostatin's analogue) 30 min before lunch. In all patients the bile output was significantly reduced: 1) prandial phase (D) 9.6 +/- 2.6 cc, and 2) post-prandial phase (E) 5.1 +/- 2.2 cc. Flow in E was significantly reduced when compared to A. Action of 0.1 mg SMS lasted about 120 min. We conclude that SMS decreases prandial and postprandial choleresis in humans.

[Trans-Kehr postoperative cholangiography in upright and horizontal positions: the morphofunctional aspects of the biliary tract]. / La colangiografía postoperatoria trans Kehr en posiciones orto y horizontal: aspectos morfológico-funcionales de las vías biliares.

To change from the lying position to the upright position, in patients without their gallbladder, causes: a) a rapid and partial emptying of the biliary ducts towards the duodenum by the amplification of the opening phasic waves activity of the sphincter of Oddi (S. O.); b) an important reduction caliber of the main biliary duct (M. B. D) and c) stability of the intraductal pressure with slight raising in upright position. These physiological concepts allow a better cholangiographic exploration by means of a drip of 60 to 70 drops per minute of diluted tri-iodic in: 1) Upright position, which gives a good image regarding the terminal choledochus; of the biliary duodenal flow, and of the reduction of the caliber of the MBD. 2) In lying down position which allows: the filling up of the complete biliary-tree with possible scarcity of information about the distal choledochus-duct; the appreciation of the degree of the expansion of the MBD, and the measuring of the delay of the emptying out of the X-ray-opaque substance in relation to what was found in the upright position. The elasticity of the walls of the biliary ducts acts efficiently in the compliance of the container and contained. In normal choledochal ducts, the top level images in the upright position do not go beyond the hepatic duct. When there are problems with the flow through the S. O., there is a filling up of the intrahepatic biliary ducts with the contrast substance introduced in the upright position.

Comparison of high-performance liquid chromatography and high-performance capillary electrophoresis for the determination of cicletanine in plasma.

A sensitive and selective high-performance capillary electrophoresis (HPCE) procedure was developed for the determination of total cicletanine in human plasma. The procedure consisted in extraction of the drug with diethyl ether and analysis by micellar electrokinetic capillary chromatography in a fused-silica capillary using sodium dodecyl sulphate in the run buffers and ultraviolet detection. The concentrations of cicletanine obtained by this method were compared with those obtained by a high-performance liquid chromatographic (HPLC) method used routinely. The within-run precision of the methods, expressed as relative standard deviation, ranged from 1.6 to 7.8% for HPLC and from 6.4 to 11.1% for HPCE. Both methods showed an adequate level of accuracy; the relative errors ranged from 0.02 to 3.25% for HPLC and from 0.21 to 2.90% for HPCE. The HPCE method required less than half the time taken by the HPLC method, making HPCE a useful alternative technique for the routine determination of cicletanine in plasma. Both methods were used to follow the time course of total cicletanine in human plasma after a single oral therapeutic dose of the drug.

Determination of cicletanine enantiomers in plasma by high-performance capillary electrophoresis.

A sensitive and selective high-performance capillary electrophoresis procedure was developed for the determination of S(+) and R(-) enantiomers of cicletanine in human plasma. The procedure consisted in extraction of the drug with diethyl ether and analysis by micellar electrokinetic capillary chromatography in a fused-silica capillary using gamma-cyclodextrins in the run buffers and ultraviolet detection. The method was linear from 10 to 500 ng/ml and the limit of detection was 10 ng/ml for each enantiomer in plasma samples. The within-run precision of the method, expressed as relative standard deviation, was 10.4 and 9.6% at 25 ng/ml for S(+) and R(-) cicletanine, and 4.2 and 4.6% at 500 ng/ml, respectively. This method has been used to follow the time course of the concentrations of the cicletanine enantiomers in human plasma after a single therapeutic dose of cicletanine given by mouth.