Cognitive control in number processing: new evidence from number compatibility effects in task-switching.

A growing body of research suggests that basic numerical abilities such as number magnitude processing are influenced by cognitive control processes. So far, evidence for number processing being affected by cognitive control processes stems primarily from observed adaptations of numerical effects to stimulus set characteristics (e.g. order or ratio of specific stimulus types). Complementing previous research on adaptation to stimulus set characteristics as an index of influences of cognitive control, the present study employed a task-switching paradigm to examine how cognitive control processes influence number processing. Participants were presented with a two-digit number and had to either judge its parity or compare its magnitude to a standard depending on a preceding cue. We expected numerical congruency effects (i.e. the unit-decade compatibility effect for magnitude comparisons and the parity congruity effect for parity judgements) to be larger in switch trials, as persisting activation of the task set of the preceding trial should increase interference. In contrast to our expectations, both numerical congruity effects were reduced following task switches as compared to repetitions. This interaction of task-switching with numerical congruency effects suggests an influence of cognitive control on basic number processing in form of persisting inhibition of previously abandoned task sets, so that these exert less influence on current number processing demands.

[Trends in Abuse of Biogenic Drugs in Parts of Germany 2007-2013]. / Entwicklung des Missbrauchs psychotroper Pflanzen und Pilze in Deutschland ­ Interpretation der Zahlen aus 3 Giftinformationszentren für die Jahre 2007­2013.

AIM OF THE STUDY: Based on an abundance of information on the internet, psychotropic plants and mushrooms are of increasing relevance as legal and cheap alternatives to other illicit drugs. Due to the lack of a German database, the abuse of selected biogenic drugs using reported exposures to 3 German Poison Information Centres (PICs) was examined. METHODS: Information on abuse of biogenic drugs was collected from the German PICs in Berlin, Erfurt and Fribourg (2007-2013). RESULTS: 602 drug abuses were reported to the selected PICs. 52% reported consumption of tropane alkaloid-containing plants (Angel's trumpet, Thorn apple, Belladonna), 25% of psilocybin-containing mushrooms and 10% of nutmeg. Angel's trumpet was identified as the most abused plant. Consumers of tropane alkaloid-containing plants were mainly adolescents, whereas the majority of the abusers of psilocybin-containing mushrooms and nutmeg were rather young grown-ups and school children, respectively. A preponderance of moderate and severe effects (55%) could be noticed for exposures to tropane alkaloid-containing plants. More than 90% of suspected cases of tropane alkaloid-containing as well as psilocybin-containing plants abuse resulted in the treatment recommendation 'surveillance in hospital'. Mydriasis, hallucinations, tachycardia and agitation were the main symptoms after the abuse of biogenic drugs. CONCLUSIONS: The data from the PICs suggest abuse of biogenic drugs in parts of Germany. A decreasing trend is observed, probably caused by the competition with new synthetic designer drugs. The results underline the dominance of Angel's trumpet in the abuse of biogenic drugs and emphasize the importance of easy accessibility for the abuse of biogenic drugs. Unexpectedly, the number of nutmeg abuse cases increased during the investigated period.

Influence of hyperoxia on diastolic myocardial and arterial endothelial function.

OBJECTIVE: Hyperoxia is known to influence cardiovascular and endothelial function, but it is unknown if there are differences between younger and older persons. The aim of this study was to monitor changes in myocardial diastolic function and flow-mediated dilatation (FMD) in younger and elderly volunteers, before and after exposure to relevant hyperbaric hyperoxia. METHODS: 51 male patients were separated into two groups for this study. Volunteers in Group 1 (n=28, mean age 26 ±6, "juniors") and Group 2 (n=23, mean age 53 ±9, "seniors") received standard HBO2 protocol (240kPa oxygen). Directly before and after hyperoxic exposure in a hyperbaric chamber we took blood samples (BNP, hs-troponin-t), assessed the FMD and echocardiographic parameters with focus on diastolic function. RESULTS: After hyperoxia we observed a high significant decrease in heart rate and systolic/diastolic FMD. Diastolic function varied in both groups: E/A ratio showed a statistically significant increase in Group 1 and remained unchanged in Group 2. E/e' ratio showed a slight but significant increase in Group 1, whereas e'/a' ratio increased in both groups. Deceleration time increased significantly in all volunteers. Isovolumetric relaxation time remained unchanged and ejection fraction showed a decrease only in Group 2. There were no changes in levels of BNP and hs-troponin-t in either group. CONCLUSION: Hyperoxia seems to influence endothelial function differently in juniors and seniors: FMD decreases more in seniors, possibly attributable to pre-existing reduced vascular compliance. Hyperoxia-induced bradycardia induced a more pronounced improvement in diastolic function in juniors. The ability of Group 1 to cope with hyperoxia-induced effects did not work in the same manner as with Group 2.

Comparison of the cough reflex test and water swallowing test in healthy participants and neurological patients.

Comparison of the cough reflex test and water swallowing test in healthy participants and neurological patients. BACKGROUND: Silent aspiration is poorly identified by traditional clinical swallowing evaluations. Recently, sevral studies have proposed the use of a cough reflex test (CRT) for screening patients at risk of aspirations. The first aithis study is to investigate the CRT thresholds of citric acid concentration for identifying cough responses in healthy participants and neurological patients. The second aim is to compare the results of the CRT with the water swallowing test (WST), a standard screening test for identifying cough responses in neurological patients. METHODS: The CRT and then the WST were administered to 100 neurological patients and 100 healthy participants. For the CRT, we administered incremental solutions of citric acid interspersed with placebo doses. We used the results of the CRT in healthy participants to define a citric acid concentration cut-off, which could be used with neurological patients as a screening for aspirations. RESULTS: As all controls coughed at a concentration of 0.1 mol/L, this was used as a cut-off in patients to identify coughing as a screening for aspiration risk. Patients showed cough reflexes at concentrations significantly higher than controls (p=0 .001). The WST was not administered to 17 patients, due to cognitive deficits and severe clinical conditions. Thirty six patients had a cough response above the screening cut-off (> 0.1 mol/L), 25 of which (30.1%) also had a positive cough response during the WST. CONCLUSION: The CRT correlated significantly with the WST. Unlike the WST, the CRT could be easily administered to severely impaired patients. Our results indicate the use of the CRT as a screening test for silent aspirators.

Secretory structures in Baccharis platypoda DC. inflorescences (Asteraceae) and characterization of the chemical composition of its secretion.

Rocky outcrop environments at high altitudes have nutrient-poor soil, where species are exposed to water scarcity and high solar radiation. Baccharis platypoda DC. occurs in such an environment and has a rigid and transparent secretion that covers the entire inflorescence. We analysed and compared the secretory structures and their chemical composition in female and male inflorescences of B. platypoda, a dioecious species, to explore chemodiversity within this species and assess potential differences between individuals. Our investigation also aims to understand the occurrence of these substances in the genus Baccharis L. Chemical compounds and secretory structures were similar in female and male inflorescences. There are glandular trichomes on the epidermis of the abaxial surface of bracts, and secretory ducts in the axis of the inflorescence, as well as in sepals, petals, and bracts. Histochemical tests were positive for phenolic compounds, flavonoids, proteins, pectin, and lipids, but not for mucilage. Flavonoid content varied between 6.24% and 9.81%, being higher in female inflorescences. Chromatography revealed the presence of several phenolic compounds, some terpenes, and other less frequent classes in both female and male inflorescences. We highlight that trichomes found on these surfaces produce abundant phenolic compounds. These act as natural defence agents, absorbing UV radiation and minimizing oxidative stress to plant cells. The chemical composition of the secretion covering the inflorescences may reflect adaptation and survival mechanisms of these organisms under extreme sun exposure.

Influence of hyperoxia and physical exercise on *OH-radical stress in humans as measured by dihydroxylated benzoates (DHB) in urine.

BACKGROUND: Hyperoxia and physical exercise are known to produce reactive oxygen species (ROS), and the *OH radical is the most aggressive among them. However, knowledge is limited about *OH stress during physical work under hyperoxic conditions. METHODS: This study monitored *OH stress in human volunteers before and after a total of 135 exposures to ambient air (control), different levels of hyperoxia at rest and challenging open-water closed-circuit dives by measurement of dihydroxylated benzoates (DHB) with HPLC by electrochemical detection in urine. RESULTS: Changes in DHB in urine after control were only 3.43 +/- 4.8% (n = 9). After exposures to 100 kPa oxygen (O2) for 110 minutes DHB revealed increases in urine of 23.14 +/- 5.12% (n = 9); exposures to 240 kPa O2 for 90 minutes increases of 22.38 +/- 8.91% (n = 8); and 280 kPa 02 for 30 minutes of 21.92 +/- 10.76% (n = 17). Closed-circuit dives in open water (45-54 minutes of 125-160 kPa O2) revealed DHB increases of 66.34 +/- 25.73% (n = 92). All results differed significantly from control (p < 0.001). The closed-circuit dives also differed significantly from all exposures to hyperoxia without exercise (p < 0.001). Standardization of "oxygen burden" during each exposure (pO2 x exposure time x VO2) allowed for comparison of different exposures vs. DHB changes and revealed goodness of linear fit of r2 = 0.432 (p < 0.0001). CONCLUSIONS: Increases in urine DHB after exposures to different levels of hyperoxia at rest and during exercise are consistent with *OH stress that is greater during exercise than at rest, although other interpretations are possible. Standardization of the individual "oxygen burden" for a given exposure may become useful in future for the estimation of *OH stress.

Physical exercise might influence the risk of oxygen-induced acute neurotoxicity.

OBJECTIVE: Hyperoxia can induce acute neurotoxicity with generalized seizures. Hyperoxia-induced reduction in cerebral blood flow velocity (CBFV) might be protective. It is unclear whether dynamic exercise during hyperoxia can overcome CBFV-reduction and thus possibly increase the risk of neurotoxicity. METHODS: We studied CBFV with both-sided transcranial Doppler with fixed transducer-position and heart rate under increasing hyperoxic conditions in nine professional military oxygen divers. The divers performed dynamic exercise on a bicycle-ergometer in a hyperbaric chamber (ergometries I-III, 21kPa, 100kPa, 150kPa pO2), with continuous blood pressure (ergometries I, II), end-tidal CO2 (PetCO2; ergometry I) being measured. RESULTS: Systolic (CBFVsyst) and diastolic CBFV (CBFVdiast) readings at rest decreased with increasing pO2. During exercise, CBFVsyst and CBFVdiast significantly increased in parallel with increasing pO2, despite reduced flow velocities at rest. ERGOMETRY I: CBFVsyst increased from 65.0 +/- 11.3 cm/second at rest to 80.2 +/- 23.4cm/s during maximum workload (n.s.), diastolic from 14.5 +/- 4.1 cm/second to 15.6 +/- 7.5 cm/s (n.s.). PetCO2 increased from 43.4 +/- 7.8mmHg to 50.0 +/- 7.5mmHg. ERGOMETRY II: CBFVsyst increased from 58.2 +/- 16.5 cm/second to 99.7 +/- 17.0 cm/s (p<0.001), diastolic from 14.0 +/- 10.7 cm/second to 29.4 +/- 11.1 cm/second (p<0.01). ERGOMETRY III: CBFVsyst increased from 54.4 +/-15.0cm/second to 109.4 +/- 22.3cm/s (p<0.001), diastolic from 14.7 +/- 10.4 cm/second to 35.5 +/- 9.3 cm/second (p<0.01). INTERPRETATION: Physical exercise overrules the decrease in CBFV during hyperoxia and leads to even higher CBFV-increases with increasing pO2. A tendency towards CO2 retainment with elevated PetCOz may be causative and thus heighten the risk of oxygen-induced neurotoxicity.

Reduction techniques for network validation in systems biology.

The rapidly increasing amount of experimental biological data enables the development of large and complex, often genome-scale models of molecular systems. The simulation and analysis of these computer models of metabolism, signal transduction, and gene regulation are standard applications in systems biology, but size and complexity of the networks limit the feasibility of many methods. Reduction of networks provides a hierarchical view of complex networks and gives insight knowledge into their coarse-grained structural properties. Although network reduction has been extensively studied in computer science, adaptation and exploration of these concepts are still lacking for the analysis of biochemical reaction systems. Using the Petri net formalism, we describe two local network structures, common transition pairs and minimal transition invariants. We apply these two structural elements for network reduction. The reduction preserves the CTI-property (covered by transition invariants), which is an important feature for completeness of biological models. We demonstrate this concept for a selection of metabolic networks including a benchmark network of Saccharomyces cerevisiae whose straightforward treatment is not yet feasible even on modern supercomputers.

Arsenic speciation in blue mussels (Mytilus edulis) along a highly contaminated arsenic gradient.

Arsenic is naturally present in marine ecosystems, and these can become contaminated from mining activities, which may be of toxicological concern to organisms that bioaccumulate the metalloid into their tissues. The toxic properties of arsenic are dependent on the chemical form in which it is found (e.g., toxic inorganic arsenicals vs nontoxic arsenobetaine), and two analytical techniques, high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and X-ray absorption spectroscopy (XAS), were used in the present study to examine the arsenic species distribution in blue mussels (Mytilus edulis) obtained from an area where there is a strong arsenic concentration gradient as a consequence of mining impacted sediments. A strong positive correlation was observed between the concentration of inorganic arsenic species (arsenic compounds with no As-C bonds) and total arsenic concentrations present in M. edulis tissues (R(2) = 0.983), which could result in significant toxicological consequences to the mussels and higher trophic consumers. However, concentrations of organoarsenicals, dominated by arsenobetaine, remained relatively constant regardless of the increasing As concentration in M. edulis tissue (R(2) = 0.307). XANES bulk analysis and XAS two-dimensional mapping of wet M. edulis tissue revealed the presence of predominantly arsenic-sulfur compounds. The XAS mapping revealed that the As(III)-S and/or As(III) compounds were concentrated in the digestive gland. However, arsenobetaine was found in small and similar concentrations in the digestive gland as well as the surrounding tissue suggesting arsenobetaine may being used in all of the mussel's cells in a physiological function such as an intracellular osmolyte.

Arsenobetaine formation in plankton: a review of studies at the base of the aquatic food chain.

Arsenobetaine is one of the major organoarsenic compounds found in aquatic organisms, including seafood and fish meant for human consumption. It has been widely studied over the last 50 years because of its non-toxic properties, and its origin is postulated to be at bottom of the aquatic food chains. The present review focuses on arsenobetaine formation in marine and freshwater plankton, comparing the arsenic compounds found in the different plankton organisms, and the methods used to assess arsenic speciation. The main findings indicate that in the marine environment, phytoplankton and micro-algae contain arsenosugars, with the first traces of arsenobetaine appearing in herbivorous zooplankton, and becoming a major arsenic compound in carnivorous zooplankton. Freshwater plankton contains less arsenobetaine than their marine relatives, with arsenosugars dominating. The possible role and formation pathways of arsenobetaine in plankton organisms are reviewed and the literature suggests that arsenobetaine in zooplankton comes from the degradation of ingested arsenosugars, and is selectively accumulated by the organism to serve as osmolyte. Several arsenic compounds such as arsenocholine, dimethylarsinoylacetate or dimethylarsinoylethanol that are intermediates of this pathway have been detected in plankton. The gaps in research on arsenobetaine in aquatic environments are also addressed: primarily most of the conclusions are drawn on culture-based experiments, and few data are present from the natural environment, especially for freshwater ecosystems. Moreover, more data on arsenic in different zooplankton species would be helpful to confirm the trends observed between herbivorous and carnivorous organisms.

Association of the interleukin-23 receptor gene variant rs11209026 with Crohn's disease in German children.

AIM: Genome-wide association studies have described variants within the interleukin-23 receptor (IL23R) locus to be associated with Crohn's disease (CD) and ulcerative colitis (UC). We investigated the association of rs11209026 (p.Arg381Gln) and rs7517847 (c.799-3588T>G) into German paediatric inflammatory bowel disease (IBD) patients and analysed IL23R transcriptional activity in colonic tissues. METHODS: The rs11209026 and rs7517847 nucleotide substitutions were determined in 353 German children with IBD (221 CD, 132 UC) and 253 controls using pre-designed TaqMan((R)) SNP genotyping assays. In selected IBD patients and controls, IL23R mRNA expression was measured using real-time PCR. RESULTS: The prevalence of the rs11209026 A allele was lower in CD patients, but not in UC patients, when compared with controls (1.8% vs 7.1%, p < 0.01). The rs7517847 variant, in contrast, was associated neither with CD nor with UC. IL23R expression was variable in IBD patients compared with controls without significant overexpression or downregulation. CONCLUSION: Our study provides additional support for the strong protection of the rs11209026 (p.Arg381Gln) variant against paediatric CD. IL23R was expressed in both CD and UC with a great variability. However, expression levels showed no significant association with the disease.

The outer membrane Omp85-like protein P39 influences metabolic homeostasis in mature Arabidopsis thaliana.

The Omp85 proteins form a large membrane protein family in bacteria and eukaryotes. Omp85 proteins are composed of a C-terminal ß-barrel-shaped membrane domain and one or more N-terminal polypeptide transport-associated (POTRA) domains. However, Arabidopsis thaliana contains two genes coding for Omp85 proteins without a POTRA domain. One gene is designated P39, according to the molecular weight of the encoded protein. The protein is targeted to plastids and it was established that p39 has electrophysiological properties similar to other Omp85 family members, particularly to that designated as Toc75V/Oep80. We analysed expression of the gene and characterised two T-DNA insertion mutants, focusing on alterations in photosynthetic activity, plastid ultrastructure, global expression profile and metabolome. We observed pronounced expression of P39, especially in veins. Mutants of P39 show growth aberrations, reduced photosynthetic activity and changes in plastid ultrastructure, particularly in the leaf tip. Further, they display global alteration of gene expression and metabolite content in leaves of mature plants. We conclude that the function of the plastid-localised and vein-specific Omp85 family protein p39 is important, but not essential, for maintenance of metabolic homeostasis of full-grown A. thaliana plants. Further, the function of p39 in veins influences the functionality of other plant tissues. The link connecting p39 function with metabolic regulation in mature A. thaliana is discussed.

Arsenic bioaccessibility and speciation in clams and seaweed from a contaminated marine environment.

The bioaccessible concentration and speciation of arsenic (soluble in a gastrointestinal medium and available for absorption into the bloodstream) were determined in softshell clams (Mya arenaria), harvested by local residents until 2005, and in seaweed (Fucus sp.) from an arsenic-contaminated marine site in Seal Harbour, Nova Scotia, Canada. Bioaccessibility extractions to simulate the human gastrointestinal environment (pH 1.5 and glycine for 1h followed by pancreatin, bile extract and pH adjustment to 7 for an additional 4h) and speciation of arsenic in extracts (HPLC-HG-AAS to target inorganic arsenic species) and whole samples (XANES) were carried out. Total arsenic for the clams from the contaminated area ranged from 218 to 228 ppm wet weight, with a bioaccessible fraction of 34-46%, and the major bioaccessible species of arsenic were inorganic. The seaweed from the contaminated area contained 27-43 ppm wet weight total arsenic, with the bioaccessible fraction ranging from 63% to 81%, and inorganic arsenic was also predominant. The predominantly inorganic nature of arsenic in the whole samples was confirmed by XANES. In concurrence with the closure of the area for clam harvesting, the clams and seaweed from Seal Harbour should probably not be used for human consumption.

Tumour-related expression of a translation-elongation factor-like protein.

We have identified a tumour-related 43 kd cytoplasmic protein (LC/p43) using a monoclonal antibody against the total proteins of human hepatoma cell line PLC/PRF/5. LC/p43 is preferentially expressed in a variety of tumours of human and animal origin, whereas no expression was detected in several normal adult tissues tested. LC/p43 expression was induced in rodent fibroblasts upon transfection with several viral oncogenes. Expression in non-transformed peripheral blood lymphocytes could be induced by treatment with phytohaemagglutinin (PHA) and subsequent culture with interleukin II, whereas retinoic acid treatment of transformed cells caused a drastic reduction of the antigen in the cells. Sequence analysis of three tryptic peptides of LC/p43 revealed 50-70% homology to different domains of the eukaryotic and prokaryotic translation-elongation factors EF1-alpha and EF-Tu, respectively.

Experiences of a poison center network with renal insufficiency in acetaminophen overdose: an analysis of 17 cases.

OBJECTIVE: Renal insufficiency is less common than liver failure in acetaminophen overdose but renal tubular damage occurs even in the absence of hepatotoxicity. Data published on this topic are rare consisting mostly of case reports or reports in a small number of patients. Presently, a larger number of patients with renal insufficiency associated with acetaminophen overdose should be analyzed using a multicenter approach. STUDY DESIGN: Retrospective analysis of patients with acetaminophen-related nephrotoxicity reported to a poison center network from 1995 to 2003. Renal insufficiency was defined as elevated serum creatinine of more than double of the normal range (>2.4 mg/dL [212 micromol/L]). Patients were classified into 4 groups (A: creatinine 2.4-5.0 mg/dL, B: creatinine>5.0 mg/dL requiring no dialysis, C: creatinine>5.0 mg/dL requiring dialysis, D: creatinine>5.0 mg/dL with fatal outcome). RESULTS: Seventeen patients were included (8 female, 9 male, average age 31.7 +/- 21.1 yrs) with 6 patients in group A (B: 7, C: 2, D: 2). In 5 patients renal insufficiency occurred without elevation of liver enzymes. Regarding possible risk factors 5 patients concomitantly ingested nephrotoxic substances, 4 presented with dehydration due to vomiting, 4 with chronic excessive dosing (overdose) of acetaminophen, 3 showed pre-existing renal insufficiency, 2 pre-existing liver disease and 2 died with multiple organ failure. CONCLUSIONS: Renal insufficiency in acetaminophen overdose mostly resolved without dialysis and occurred isolated without hepatotoxicity in less than one-third of the investigated patients. Conditions which might play a role as influencing factors for renal complications included concomitant ingestion of nephrotoxic drugs, dehydration, chronic excessive dosing (overdose) of acetaminophen, pre-existing renal or liver disease and multiple organ failure. Renal function should be monitored in acetaminophen overdose particularly in patients showing the latter comorbidity.

Growth hormone (GH) stimulates insulin-like growth factor-I (IGF-I) and IGF-I-binding protein-3, but not GH receptor gene expression in livers of juvenile rats.

In the adult rat, expression of the liver GH receptor, insulin-like growth factor-I (IGF-I), and IGF-I-binding protein-3 (IGFBP-3) genes has been shown to be under GH control. Additionally, hypophysectomy and GH treatment have a differential effect on the relative abundance of liver IGF-I mRNA variants in adult rats. To further elucidate the time of appearance and the extent of GH control of liver GH receptor, IGF-I, and IGFBP-3 gene expression, we studied the effect of hypophysectomy and GH and IGF-I treatment in juvenile rats. Male Wistar rats were hypophysectomized (Hx) on postnatal day 26 and received twice daily sc injections of saline, recombinant human GH (2.5 U/kg.day), or recombinant human IGF-I (500 micrograms/kg.day) for 7 days. Sham-operated rats received the same treatment. Hx animals also received T4 (20 micrograms/kg.day). In Hx animals, there was a significant reduction in body weight (69.8 +/- 6.6 vs. 100.4 +/- 5.4 g; P < 0.001). GH, but not IGF-I, treatment increased body weight (79.6 +/- 9.6 g after GH vs. 69.8 +/- 6.6 g before GH; P < 0.05). GH treatment partially maintained liver, kidney, and lung weights in Hx animals and increased them in intact animals, whereas IGF-I treatment did so only in the lungs of intact and Hx animals. Serum GH and IGF-I levels were markedly reduced in Hx animals compared with those in intact controls, and GH treatment maintained, albeit partially, circulating IGF-I levels compared with those in saline-treated Hx animals. IGF-I mRNA levels were markedly reduced in Hx liver (25.0 +/- 5.4%; P < 0.001 compared with intact controls). GH treatment for 7 days increased IGF-I mRNA levels by 4.8-fold over the levels in 9-day Hx animals and increased IGF-I mRNA levels by 2.2-fold in control rats. Hypophysectomy decreased exon 2-containing transcripts by 7.0-fold and exon 1-containing transcripts by 4.1-fold. GH treatment, however, affected both exon 1- and exon 2-containing transcripts similarly. Hepatic IGFBP-3 mRNA levels were reduced in Hx (53.2 +/- 1.8%; P < 0.01 compared with intact controls) and IGF-treated Hx animals, but were not decreased in Hx GH-treated animals (100.6 +/- 9.5). No changes in GH receptor or GH-binding protein mRNA levels were caused by Hx, GH, or IGF-I treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

The genetic determinants of the CYP3A5 polymorphism.

CYP3A proteins comprise a significant portion of the hepatic cytochrome P450 (CYP) protein and they metabolize around 50% of drugs currently in use. The dissection of the individual contributions of the four CYP3A genes identified in humans to overall hepatic CYP3A activity has been hampered by sequence and functional similarities. We have investigated the expression of CYP3A5 and its genetic determinants in a panel of 183 Caucasian liver samples. CYP3A5 expression is increased in 10% of livers in this ethnic group. Using a high density map of CYP3A5 variants, we searched for genetic markers of the increased CYP3A5 expression. In agreement with an independent, recent study, we report that a SNP within intron 3 (g.6986G>A) is the primary cause of the CYP3A5 protein polymorphism. The frequencies of the g.6986A variant which allow for normal splicing of CYP3A5 transcripts are 5% in Caucasians, 29% in Japanese, 27% in Chinese, 30% in Koreans and 73% in African-Americans. In the last ethnic group, the expression of CYP3A5 in some individuals who carry the g.6986A variant is affected adversely by a frame shift mutation (CYP3A5*7, D348., q = 0.10). In summary, these results should add to efforts to identify clinically relevant, CYP3A5-specific reactions and to further elucidate traits responsible for variable expression of the entire CYP3A family.

Genomic organization of the human CYP3A locus: identification of a new, inducible CYP3A gene.

Proteins encoded by the human CYP3A genes metabolize every second drug currently in use. The activity of CYP3A gene products in the general population is highly variable and may affect the efficacy and safety of drugs metabolized by these enzymes. The mechanisms underlying this variability are poorly understood, but they include gene induction, protein inhibition and unknown genetic polymorphisms. To better understand the regulation of CYP3A expression and to provide a basis for a screen of genetic polymorphisms, we determined and analysed the sequence of the human CYP3A locus. The 231 kb locus sequence contains the three CYP3A genes described previously (CYP3A4, CYP3A5 and CYP3A7), three pseudogenes as well as a novel CYP3A gene termed CYP3A43. The gene encodes a putative protein with between 71.5% and 75.8% identity to the other CYP3A proteins. The highest expression level of CYP3A43 mRNA is observed in the prostate, an organ with extensive steroid metabolism. CYP3A43 is also expressed in several other tissues including liver, where it can be induced by rifampicin. CYP3A43 transcripts undergo extensive splicing. The identification of a new member of the CYP3A family and the characterization of the full CYP3A locus will aid efforts to identify the genetic variants underlying its variable expression. This, in turn, will lead to a better optimization of therapies involving the numerous substrates of CYP3A proteins.

Applying machine learning methods for finding significant amino acid properties in proteins.

There are several possibilities for definition and derivation of sequence patterns associated with structural motifs, in particular on the secondary structure level which may be used to predict these structure elements. Sequence patterns consist of a number of consecutive positions along the polypeptide chain from which a certain quantity is specified. One of the important factors in deriving sequence patterns in terms of amino acid properties is how to find the most characteristic properties to specify a certain position and thus to avoid redundant physical information. We have applied machine learning methods to select the most significant amino acid properties describing a structurally determined sequence position. Results are given for the beginning of alpha-helices. These methods may link the gap between amino acid patterns and property patterns and thus are valuable to improve protein structure prediction.