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.

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.

Hyperthermophilic redox chemistry: a re-evaluation.

The redox chemistry of Pyrococcus furiosus rubredoxin and ferredoxin has been studied as a function of temperature in direct voltammetry and in EPR monitored bulk titrations. The Ems of both proteins, measured with direct voltammetry, have a normal (linear) temperature dependence and show no pH dependence. EPR monitoring is not a reliable method to determine the temperature dependence of the Em: upon rapid freezing the proteins take their conformation corresponding to the freezing point of the solution.

High-energy spectrophotometer for rapid constituent analysis in the range of 0.25-2.4 mum.

This publication describes a constituent analyzer which uses a concave holographic grating for high-energy throughput, a conjugate cam drive to allow up to ten spectral scans per second, a microprocessor for data gathering and system control, and a minicomputer for the complex statistical computations required in the interpretation of the spectral data gathered. The instrument was specifically developed for quantitative measurement of food constituents in food processing and quality control. However, as a general state-of-the-art spectrophotometer it was found to be a valuable tool in other disciplines such as industrial, clinical, and medical applications.

[Nap polysomnography: sufficient grounds for initiating CPAP treatment?]. / Polisomnografía de siesta: es suficiente para iniciar tratamiento con CPAP?

UNLABELLED: Nap polysomnography (NPSG) is a technique for rapid diagnosis of sleep apnea-hypopnea syndrome (SAHS). Although an apnea-hypopnea index (AHI) over 10 indicates a diagnosis of SAHS, treatment with nasal continuous positive airway pressure (CPAP) starts when the AHI exceeds 30. OBJECTIVE: To determine the diagnostic yield of NPSG for initiating CPAP and to evaluate the different types of polysomnographic findings. METHODS: Two hundred ninety-six patients suspected of having SAHS underwent NPSG lasting three hours. NPSG findings were considered positive at AHI > 30; normal at AHI < 10 with non-REM and REM sleep (more than 10%); invalid if the patient slept less than 60 minutes; and inconclusive if AHI was between 10 and 30 with REM, if AHI was < 30 without REM, or if upper airway resistance syndrome (UAS) was suspected. Positive and normal polysomnographic findings were considered diagnostic and the invalid and inconclusive findings were considered non-diagnostic. We also observed whether SAHS was predominantly obstructive, predominantly hypopneic, central-mixed, central-obstructive or miscellaneous, based on the type of event detected mot often during NPSG. RESULTS: Seventy percent of the NPSG were diagnostic (55% positive and 15% normal) and 30% were not (12% invalid and 18% inconclusive). Fifty-five percent of the positive NPSGs were predominantly obstructive, 29% were predominantly hypopneic, 8% were central-mixed, 4% were central-obstructive and 4% were miscellaneous. CONCLUSIONS: The diagnostic value of NPSG for initiating CPAP treatment is high. Predominantly hypopneic forms are particularly common.

Cytoprotective effect of somatostatin in a rat model of hepatic ischemic reperfusion.

To evaluate the possible cytoprotective effect of somatostatin in hepatic ischemic reperfusion injury we used 75 adult male Wistar rats randomly separated into four groups. The rats in group 1 underwent sham operations, and those in group 2 underwent resection of the median and left lateral lobes. The rats in group 3 underwent a 90-min period of ischemia of the right lateral lobe, which we induced by temporarily occluding the right portal vein and the hepatic artery. On restoration of flow to the right lateral lobe, the median and left lateral lobes (about 80% of total liver mass) were excised (and later assayed for thymidine kinase basal activity). The rats in group 4 were given the same treatment as group 3 rats except that a saline solution of somatostatin was infused at a rate of 2 micrograms/min starting at laparotomy and lasting 24 hr. The rats in groups 1, 2 and 3 were infused with saline. Rats in groups 2, 3 and 4 were randomly assigned to two subgroups; one of these subgroups was observed until spontaneous death, and rats in the other group were killed 24 hr after the procedure for obtaining peripheral blood and liver samples. Somatostatin infusion improved the animals' survival rates from 0% (group 3) to 60% (group 4) (p < 0.05) and decreased bilirubin levels (0.78 +/- 0.17 mg/dl, n = 15 [group 4] vs. 1.69 +/- 0.04 mg/dl, n = 15 [group 3]; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute experimental pancreatitis in rat induced by sodium taurocholic acid: objective quantification of pancreatic necrosis.

Retrograde injection of 5% sodium taurocholic acid (TA) in Wistar rat pancreatic duct is followed by acute pancreatitis, resulting in 100% mortality within 36 h. Biochemical determinations show raised levels of amylase in ascites and blood. Necrosis has been measured using seven morphometric characteristics of pathological changes that add precise information on the type and extension of the pancreatic lesion. The percentage of necrotic tissue (by area) seems to be the most objective parameter. Necrosis appears 6 h after TA infusion, being 5.77% in extent after 12 h, 14.9% after 24 h and animals die with an area of 29.5% necrosis. This experimental model seems to one in which physiopathological and therapeutic trials on acute pancreatitis may be tried out.

Somatostatin in the treatment of severe upper gastrointestinal bleeding: a multicentre controlled trial.

To evaluate the effectiveness of somatostatin versus combined cimetidine and pirenzepine in the treatment of upper gastrointestinal (GI) bleeding of peptic origin, a multicentre controlled, prospective, randomized and double blind trial has been undertaken in 60 subjects. Strict selection criteria were followed. All subjects were diagnosed by endoscopy during the first 18 h after admission. Endoscopic stigmata of recent haemorrhage were also evaluated. Sixty-five per cent of the subjects presented with severe upper GI bleeding (blood pressure less than or equal to 100 mmHg, pulse rate greater than or equal to 110, haematocrit less than or equal to 30 per cent), and in 71.6 per cent stigmata were found. Thirty patients (Group 1) received a somatostatin infusion (250 micrograms/h continuously during 120 h) and 30 patients (Group 2) received cimetidine (200 mg IV every 4 h for 5 days) and pirenzepine (10 mg IV every 8 h for 5 days). Both groups were homogeneous for sex, age, backgrounds, bleeding source, grade of bleeding (moderate or severe) and presence or not of stigmata. Bleeding stopped in 27 subjects of Group 1 (90 per cent and in 20 subjects of Group 2 (66.67 per cent) (P less than 0.05, chi 2 test). The time until the bleeding stopped was significantly shorter in patients of group 1 (3.44 +/- 0.53 h) than in patients of group 2 (8.12 +/- 1.94 h) (P less than 0.05, Mann-Whitney U test). The number of blood units required for Group 1 (2.26 +/- 0.35) was significantly lower than the one required for Group 2 (3.90 +/- 0.51) (P less than 0.005, Wilcoxon test). Significant differences were not observed between the two groups regarding cross-over subjects, re-bleeding, surgery (P = 0.0635, Fisher's exact test) and hospital stay. The mortality of the trial was 5 per cent. There was no toxicity during somatostatin, cimetidine or pirenzepine infusion. In conclusion, somatostatin was more effective than cimetidine plus pirenzepine in the control of severe upper GI bleeding of peptic origin, with a lower interval time to stop bleeding and reduced transfusion requirements.