CYP2D6 genotype is not associated with survival in breast cancer patients treated with tamoxifen: results from a population-based study

PURPOSE

A number of studies have tested the hypothesis that breast cancer patients with low-activity CYP2D6 genotypes achieve inferior benefit from tamoxifen treatment, putatively due to lack of metabolic activation to endoxifen. Studies have provided conflicting data, and meta-analyses suggest a small but significant increase in cancer recurrence, necessitating additional studies to allow for accurate effect assessment. We conducted a retrospective pharmacogenomic analysis of a prospectively collected community-based cohort of patients with estrogen receptor-positive breast cancer to test for associations between low-activity CYP2D6 genotype and disease outcome in 500 patients treated with adjuvant tamoxifen monotherapy and 500 who did not receive any systemic adjuvant therapy.

METHODS

Tumor-derived DNA was genotyped for common, functionally consequential CYP2D6 polymorphisms (*2, *3, *4, *6, *10, *41, and copy number variants) and assigned a CYP2D6 activity score (AS) ranging from none (0) to full (2). Patients with poor metabolizer (AS = 0) phenotype were compared to patients with AS > 0 and in secondary analyses AS was analyzed quantitatively. Clinical outcome of interest was recurrence free survival (RFS) and analyses using long-rank test were adjusted for relevant clinical covariates (nodal status, tumor size, etc.).

RESULTS

CYP2D6 AS was not associated with RFS in tamoxifen treated patients in univariate analyses (p > 0.2). In adjusted analyses, increasing AS was associated with inferior RFS (Hazard ratio 1.43, 95% confidence interval 1.00-2.04, p = 0.05). In patients that did not receive tamoxifen treatment, increasing CYP2D6 AS, and AS > 0, were associated with superior RFS (each p = 0.0015).

CONCLUSIONS

This population-based study does not support the hypothesis that patients with diminished CYP2D6 activity achieve inferior tamoxifen benefit. These contradictory findings suggest that the association between CYP2D6 genotype and tamoxifen treatment efficacy is null or near null, and unlikely to be useful in clinical practice.

Age-Related Changes in MicroRNA Expression and Pharmacogenes in Human Liver

Developmental changes in the liver can significantly impact drug disposition. Due to the emergence of microRNAs (miRNAs) as important regulators of drug disposition gene expression, we studied age-dependent changes in miRNA expression. Expression of 533 miRNAs was measured in 90 human liver tissues (fetal, pediatric [1-17 years], and adult [28-80 years]; n = 30 each). In all, 114 miRNAs were upregulated and 72 were downregulated from fetal to pediatric, and 2 and 3, respectively, from pediatric to adult. Among the developmentally changing miRNAs, 99 miRNA-mRNA interactions were predicted or experimentally validated (e.g., hsa-miR-125b-5p-CYP1A1; hsa-miR-34a-5p-HNF4A). In human liver samples (n = 10 each), analyzed by RNA-sequencing, significant negative correlations were observed between the expression of >1,000 miRNAs and mRNAs of drug disposition and regulatory genes. Our data suggest a mechanism for the marked changes in hepatic gene expression between the fetal and pediatric developmental periods, and support a role for these age-dependent miRNAs in regulating drug disposition.

A randomized control trial of a psychosocial intervention for caregivers of allogeneic hematopoietic stem cell transplant patients: effects on distress

Caregivers of patients receiving allogeneic hematopoietic stem cell transplants (Allo-HSCT) serve a pivotal role in patient care but experience high stress, anxiety, and depression as a result. We theorized that a stress management adapted for Allo-HSCT caregivers would reduce distress compared to treatment as usual (TAU). From 267 consecutive caregivers of Allo-HSCT patients approached, 148 (mean=53.5 years, 75.7% female) were randomized to either psychosocial intervention (n=74) or TAU (n=74). Eight 1-on-1 stress management sessions delivered across the 100 day post-transplant period focused on understanding stress, changing role(s) as caregiver, cognitive behavioral stress management, pacing respiration, and identifying social support. Primary outcomes included perceived stress (psychological) and salivary cortisol awakening response (CAR) (physiological). Randomized groups were not statistically different at baseline. Mixed models analysis of covariance (intent-to-treat) showed that intervention was associated with significantly lower caregiver stress 3 months post-transplant (Mean=20.0, CI₉₅=17.9-22.0) compared to TAU (Mean=23.0, CI₉₅=21.0-25.0) with an effect size (ES) of 0.39 (p=0.039). Secondary psychological outcomes, including depression and anxiety, were significantly reduced with ESs of 0.46 and 0.66 respectively. Caregiver CAR did not differ from non-caregiving controls at baseline and was unchanged by intervention. Despite significant caregiving burden, this psychosocial intervention significantly mitigated distress in Allo-HSCT caregivers.

Genome-wide discovery of genetic variants affecting tamoxifen sensitivity and their clinical and functional validation

BACKGROUND

Beyond estrogen receptor (ER), there are no validated predictors for tamoxifen (TAM) efficacy and toxicity. We utilized a genome-wide cell-based model to comprehensively evaluate genetic variants for their contribution to cellular sensitivity to TAM.

DESIGN

Our discovery model incorporates multidimensional datasets, including genome-wide genotype, gene expression, and endoxifen-induced cellular growth inhibition in the International HapMap lymphoblastoid cell lines (LCLs). Genome-wide findings were further evaluated in NCI60 cancer cell lines. Gene knock-down experiments were performed in four breast cancer cell lines. Genetic variants identified in the cell-based model were examined in 245 Caucasian breast cancer patients who underwent TAM treatment.

RESULTS

We identified seven novel single-nucleotide polymorphisms (SNPs) associated with endoxifen sensitivity through the expression of 10 genes using the genome-wide integrative analysis. All 10 genes identified in LCLs were associated with TAM sensitivity in NCI60 cancer cell lines, including USP7. USP7 knock-down resulted in increasing resistance to TAM in four breast cancer cell lines tested, which is consistent with the finding in LCLs and in the NCI60 cells. Furthermore, we identified SNPs that were associated with TAM-induced toxicities in breast cancer patients, after adjusting for other clinical factors.

CONCLUSION

Our work demonstrates the utility of a cell-based model in genome-wide identification of pharmacogenomic markers.

Pancreatic endocrine neoplasms: a current update on genetics and imaging

Pancreatic endocrine neoplasms are rare pancreatic tumours that may occur sporadically or as part of inherited syndromes such as multiple endocrine neoplasia-1 syndrome, von Recklinghausen disease, von Hippel-Lindau syndrome and tuberous sclerosis complex. Recent advances in the genetics and pathology of hereditary syndromes have provided valuable insights into the pathophysiology and biology of sporadic pancreatic endocrine neoplasms. Evolving molecular data on the biology of these neoplasms have the potential for diagnostic, therapeutic and prognostic use.

A SNP in steroid receptor coactivator-1 disrupts a GSK3β phosphorylation site and is associated with altered tamoxifen response in bone

The coregulator steroid receptor coactivator (SRC)-1 increases transcriptional activity of the estrogen receptor (ER) in a number of tissues including bone. Mice deficient in SRC-1 are osteopenic and display skeletal resistance to estrogen treatment. SRC-1 is also known to modulate effects of selective ER modulators like tamoxifen. We hypothesized that single nucleotide polymorphisms (SNP) in SRC-1 may impact estrogen and/or tamoxifen action. Because the only nonsynonymous SNP in SRC-1 (rs1804645; P1272S) is located in an activation domain, it was examined for effects on estrogen and tamoxifen action. SRC-1 P1272S showed a decreased ability to coactivate ER compared with wild-type SRC-1 in multiple cell lines. Paradoxically, SRC-1 P1272S had an increased protein half-life. The Pro to Ser change disrupts a putative glycogen synthase 3 (GSK3)β phosphorylation site that was confirmed by in vitro kinase assays. Finally, knockdown of GSK3β increased SRC-1 protein levels, mimicking the loss of phosphorylation at P1272S. These findings are similar to the GSK3β-mediated phospho-ubiquitin clock previously described for the related coregulator SRC-3. To assess the potential clinical significance of this SNP, we examined whether there was an association between SRC-1 P1272S and selective ER modulators response in bone. SRC-1 P1272S was associated with a decrease in hip and lumbar bone mineral density in women receiving tamoxifen treatment, supporting our in vitro findings for decreased ER coactivation. In summary, we have identified a functional genetic variant of SRC-1 with decreased activity, resulting, at least in part, from the loss of a GSK3β phosphorylation site, which was also associated with decreased bone mineral density in tamoxifen-treated women.

Use of germ-line single nucleotide polymorphisms (SNPs) in drug transporters (ABCG2/ABCB1) and tubulin (TUBB4) to predict survival in patients with metastatic castrate-resistant prostate cancer (CRPC) receiving docetaxel

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Background: Multiple treatment options now exist for metastatic CRPC patients (pts). Germ-line SNPs in docetaxel (D) transport, metabolism, binding site, and degradation genes may contribute to variability in outcomes observed in D treated CRPC pts.

Methods: Between 1/07 and 10/08, all PCa pts seen in the Indiana University Simon Cancer Center oncology clinics were approached for recruitment to the Prostate Cancer Genetic Risk Evaluation of SNPs Study (PROGRESS). Participants completed a demographic and clinical questionnaire and provided a blood sample. Only CRPC pts treated with D were included in this analysis. Germ-line DNA was analyzed for SNP genotyping on a 128-SNP chip using a TaqMan OpenArray GT Kit (Applied Biosystems). The chip included genes critical to D signaling, transport, and elimination with minor allele frequencies > 5%. Pts were followed for progression-free (PFS) and overall survival (OS). Univariable analyses were performed to identify significant associations between SNP genotype, clinical parameters, and PFS and OS outcomes.

Results: 60 pts with metastatic CRPC initiated on D enrolled. Demographics included: age (median) – 69 yrs, ECOG PS 0– 40%, prostate specific antigen (PSA) (median) – 129.9 ng/ml, PSA doubling time (median) – 1.8 months, visceral mets –25%. No clinical parameters were associated with PFS and OS. Significant SNP associations are summarized below.

Conclusions: Differences in germ-line ABCG2, ABCB1, and TUBB4 SNPs may contribute to variation in clinical outcomes in CRPC pts treated with D.

[Table: see text]

[Table: see text]

Germ-line single nucleotide polymorphism (SNP) predictors of progression-free survival and overall survival in patients with advanced prostate cancer treated with androgen-deprivation therapy (ADT)

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Background: Significant variation in response duration and overall survival exists among prostate cancer (PCa) patients treated with ADT. Germ-line SNPs affecting function of genes critical to hormone synthesis, transport, metabolism, binding sites, and degradation may contribute to variability in clinical outcomes observed in PCa patients treated with ADT.

Methods: Between 1/07 and 10/08, all PCa patients seen in the Indiana University Simon Cancer Center oncology clinics were approached for recruitment to the Prostate Cancer Genetic Risk Evaluation of SNPs Study (PROGRESS). Participants completed a demographic and clinical questionnaire and provided a peripheral blood sample. Only patients with confirmed ADT initiation dates were included in this analysis. Germ-line DNA was analyzed for SNP genotyping on a 128-SNP chip using a TaqMan OpenArray GT Kit (Applied Biosystems). The chip included genes critical to hormone signaling, transport, and elimination pathways with minor allele frequencies > 5%. Patients were followed for progression-free survival (PFS) and overall survival (OS) endpoints. Univariable analyses were performed to identify significant associations between SNP genotype, clinical parameters, and PFS and OS outcomes.

Results: 107 patients with PCa initiated on ADT enrolled. Demographics included: age (median)–69 yrs, prostate specific antigen (PSA) (median)–28.0 ng/ml, PSA doubling time (median)–4.9 months, biochemical/metastatic–25%/75%, concurrent anti-androgen therapy–44%. No clinical parameters were associated with PFS and OS. Significant SNP associations with PFS and OS are summarized in the Table.

Conclusions: Interpatient differences in hormone pathway germ-line SNPs may contribute to variability in clinical outcomes in patients treated with ADT.

[Table: see text]

[Table: see text]

Androgen pathway constitutional polymorphism predictors of progression-free and overall survivals in advanced castrate-resistant prostate cancer (CRPC) patients treated with ketoconazole (KC)

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Background: Recent trials have highlighted the clinical utility of second-line hormonal therapies for CRPC. KC, an oral inhibitor of CYP3A4 and CYP17, is commonly used in this setting. Germline SNPs in genes critical to hormone synthesis, transport, metabolism, binding sites, and degradation may contribute to variability in outcomes observed in KC treated CRPC pts.

Methods: Between 1/07 and 10/08, all PCa pts seen in the Indiana University Simon Cancer Center oncology clinics were approached for recruitment to the Prostate Cancer Genetic Risk Evaluation of SNPs Study (PROGRESS). Participants completed a demographic and clinical questionnaire and provided a peripheral blood sample. Only pts with initiated on KC were included in this analysis. Germline DNA was analyzed for SNP genotyping on a 128-SNP chip using a TaqMan OpenArray GT Kit. The chip included genes critical to hormone signaling, transport, and elimination pathways with minor allele frequencies > 5%. Pts were followed for progression-free survival (PFS) and overall survival (OS) endpoints. Univariable analyses were performed to identify significant associations between SNP genotype, clinical parameters, and PFS and OS outcomes.

Results: Between January 2007 and October 2008, 39 pts with CRPC initiated on KC therapy enrolled. Demographics included: age (median) – 70 yrs, prostate specific antigen (PSA) (median) – 13.0 ng/ml, PSA doubling time (median) – 2.9 months, metastatic –85%, ECOG PS 0– 74%. Age < 70 was associated with shorter PFS (p=0.010) and age > 70 was associated with shorter OS (p=0.030). SNPs significantly associated with PFS and OS are summarized in the table.

Conclusions: Interpatient differences in hormonal pathway germline SNPs may contribute to variability in clinical outcomes in pts treated with KC.

[Table: see text]

No significant financial relationships to disclose.

Genetic variation in radiation and platinum pathways predicts severe acute radiation toxicity in patients with esophageal adenocarcinoma treated with cisplatin-based preoperative radiochemotherapy: results from the Eastern Cooperative Oncology Group

PURPOSE

Germline genetic variations may partly explain the clinical observation that normal tissue tolerance to radiochemotherapy varies by individual. Our objective was to evaluate the association between single-nucleotide polymorphisms (SNPs) in radiation/platinum pathways and serious treatment-related toxicity in subjects with esophageal adenocarcinoma who received cisplatin-based preoperative radiochemotherapy.

METHODS

In a multicenter clinical trial (E1201), 81 eligible treatment-naïve subjects with resectable esophageal adenocarcinoma received cisplatin-based chemotherapy concurrent with radiotherapy, with planned subsequent surgical resection. Toxicity endpoints were defined as grade ≥3 radiation-related or myelosuppressive events probably or definitely related to therapy, occurring during or up to 6 weeks following the completion of radiochemotherapy. SNPs were analyzed in 60 subjects in pathways related to nucleotide/base excision- or double stranded break repair, or platinum influx, efflux, or detoxification.

RESULTS

Grade ≥3 radiation-related toxicity (mostly dysphagia) and myelosuppression occurred in 18 and 33% of subjects, respectively. The variant alleles of the XRCC2 5' flanking SNP (detected in 28% of subjects) and of GST-Pi Ile-105-Val (detected in 65% of subjects) were each associated with higher odds of serious radiation-related toxicity compared to the major allele homozygote (47% vs. 9%, and 31% vs. 0%, respectively; P = 0.005). No SNP was associated with myelosuppression.

CONCLUSIONS

This novel finding in a well-characterized cohort with robust endpoint data supports further investigation of XRCC2 and GST-Pi as potential predictors of radiation toxicity.

A Single Nucleotide Polymorphism in Steroid Receptor Coactivator-1 Diminishes the Coactivation of ERα

Estrogen signaling is critical in the progression of a large fraction of breast cancers as well as in the maintenance of bone mineral density. Generally speaking, Tamoxifen, a selective estrogen receptor modulator (SERM), blocks estrogen signaling in the breast by acting as an antagonist at the same time as promoting estrogen signaling in the bone by acting as an agonist. This tissue specific action characteristic of SERMs is thought to be maintained by the balance of levels and/or activities of estrogen receptor (ER) coregulators. Because of this critical role, single nucleotide polymorphisms (SNPs) in ER coregulators could have a dramatic effect on tamoxifen action.Previous studies have implicated steroid receptor coactivator-1 (SRC-1) as a critical coregulator for the mixed antagonist-agonist specificity of tamoxifen. By using an ERE-Tk-Luciferase transient transfection assay, we have shown that a SNP causing the amino acid change P1272S in SRC-1 dramatically reduces its ability to coactivate ERα.To assess the impact of this SNP on tamoxifen action in breast cancer we decided to genotype the SRC-1 P1272S SNP in a breast tumor DNA bank. This bank was generated from archived tumors from individuals either exclusively receiving adjuvant tamoxifen or not receiving any adjuvant therapy following surgical resection. Currently, the bank is composed of 1000 samples divided equally among the two groups. Genotyping for the SRC-1 P1272S SNP is currently underway.Since SRC-1 has also been shown to be important in proper maintenance of bone mineral density (BMD) and in the agonist action of tamoxifen in certain tissues, we also assessed the impact of the P1272S SNP in bone following tamoxifen therapy. We genotyped breast cancer patients exclusively receiving tamoxifen therapy (i.e. no chemotherapy, no radiation) who had lumbar (n=113) and/or hip (n=108) BMD scans before and after 12 months of tamoxifen therapy. We observed a significant association between the SNP and bone loss; women harboring the P1272S SNP lost 6.4% of their lumbar BMD, while women with the WT version lost only 1.3% of their lumbar BMD.These findings illustrate the critical role of SRC-1 in tamoxifen action in bone, and potentially other hormone responsive tissues. Studies are ongoing to decipher the mechanism for decreased coactivation activity of the SNP, and also to extend the clinical association studies.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 66.

Relationship of cytochrome P450 pharmacogenetics to the effects of yohimbine on gastrointestinal transit and catecholamines in healthy subjects

Alpha-2 adrenergic receptors tonically inhibit colonic motility and the alpha(2)-adrenergic antagonist yohimbine, given intravenously, increased colonic tone in humans. However, the effect of yohimbine on colonic transit in humans is unknown. In this study, 30 healthy volunteers were randomized to yohimbine 16.2 mg p.o. t.i.d. or identical placebo for 7 days. We evaluated gastric emptying, small intestinal, and colonic transit by scinitigraphy, bowel habits, haemodynamics and plasma catecholamines. As cytochrome P450 enzymes metabolize yohimbine, P450 genotypes (CYP2D6 and CYP3A4) were determined in 25 of 30 subjects who consented to genetic studies. The relationship between drug metabolizer status predicted by CYP2D6 and CYP3A4 and effects of yohmibine were assessed. Compared to placebo, yohimbine increased (P < or = 0.02) diastolic blood pressure, plasma noradrenaline concentrations and maximum tolerated volume during the satiation test [yohimbine (1241 +/- 88, mean +/- SEM) vs placebo (1015 +/- 87), P = 0.054]. However, yohimbine did not affect gastrointestinal transit. Based on CYP2D6 and CYP3A4 alleles, seven and 18 subjects were, respectively, extensive (EM) and poor (PM) metabolizers of yohimbine. Compared to EM, PM of yohimbine had a greater increase in plasma noradrenaline (P = 0.1 for PM vs EM), lower maximum tolerated volumes (1120 +/- 95 vs 1484 + 131 mL, P = 0.02), and faster colonic transit (i.e. GC(24) was 3.0 +/- 0.4 vs 2.1 +/- 0.5, P = 0.1). These data suggest that CYP2D6 and CYP3A4 genotypes which determine the metabolism of yohimbine may influence its sympathetic and gastrointestinal effects.

Cytochrome P450 3A5 genotype is associated with verapamil response in healthy subjects

We hypothesized that CYP3A5 genotype contributes to the interindividual variability in verapamil response. Healthy subjects (n=26) with predetermined CYP3A5 genotypes were categorized as expressers (at least one CYP3A5(*)1 allele) and nonexpressers (subjects without a CYP3A5(*)1 allele). Verapamil pharmacokinetics and pharmacodynamics were determined after 7 days of dosing with 240 mg daily. There was a significantly higher oral clearance of R-verapamil (165.1+/-86.4 versus 91.2+/-36.5 l/h; P=0.009) and S-verapamil (919.4+/-517.4 versus 460.2+/-239.7 l/h; P=0.01) in CYP3A5 expressers compared to nonexpressers. Consequently, CYP3A5 expressers had significantly less PR-interval prolongation (19.5+/-12.3 versus 44.0+/-19.4 ms; P=0.0004), and had higher diastolic blood pressure (69.2+/-7.5 versus 61.6+/-5.1 mm Hg; P=0.036) than CYP3A5 nonexpressers after 7 days dosing with verapamil. CYP3A5 expressers display a greater steady-state oral clearance of verapamil and may therefore experience diminished pharmacological effect of verapamil due to a greater steady state oral clearance.

Uncertainty in rate loss corrections based on counting a periodic pulser

Tomographic gamma scanning of waste produces three-dimensional transmission and emission images. These are used to derive item-specific attenuation correction factors that improve the accuracy of non-destructive waste assay. For each vertical layer, data grabs of short duration are acquired as the waste item is rotated and translated. The image reconstruction demands accurate rate loss corrections to minimize assay bias. For this application a pulser was used to perform the necessary rate loss corrections. In this work, we summarize the benefits of the pulser approach and review the basic principles on which the method is based. We extend the treatment to include a derivation of the expression for the uncertainty in the net pulser peak area in the presence of an underlying continuum. We report experimental results, taken using a Canberra model WM2900 Tomographic Gamma Scanner, over a broad range of count-rates and peak-to-continuum ratios. Repeat counts under controlled conditions allowed the correction factor and its variance to be determined and compared against expectations. These results confirm the validity of the correction factor formula and the corresponding expression for its uncertainty. The rate loss analysis has been built into a Monte Carlo Replicate engine to allow the uncertainty to be propagated into the total measurement uncertainty of the final assay.

The on-line characterization of a radium slurry by gamma-ray spectrometry

We have developed an in-line monitor to directly measure the (226)Ra concentration in a nuclear waste stream using quantitative gamma-ray spectrometry applied to the 186keV emission. The waste stream is in the form of a slurry composed of the solid waste material mixed with water. The concentration measurement includes a self-attenuation correction factor determined from a transmission measurement using the 122keV gamma from (57)Co. Presented here is the model for the measurement system and results from some initial tests.

Oxygen-limited autotrophic nitrification/denitrification by ammonia oxidisers enables upward motion towards more favourable conditions

The hypothesis is formulated that in case of oxygen limitation in the sediment, nitrifiers switch from nitrification to oxygen-limited autotrophic nitrification-denitrification (OLAND) in order to survive and maintain activity. During OLAND, ammonium is oxidised using nitrite as e-acceptor to form dinitrogen gas. As an additional advantage they benefit from the gaseous N(2) formed as a means of transport. In this way, the nitrifiers can move out of the sediment and rise through the water column towards more favourable conditions. At the surface, the bacteria could take up oxygen, and recommence nitrification. In order to test this hypothesis, nitrifying sediment with an overlaying water column was simulated in lab-scale columns. Nitrogen transformations and material transport through the water column were followed after addition of different forms of nitrogen under oxygen-limited conditions. (15)N-labelling experiments showed a large contribution of OLAND to the observed nitrogen deficits. Nitrifier enumerations, fluorescent in situ hybridisation and 16S rRNA gene analysis revealed increased populations of ammonia oxidising nitrifiers in the upper water layers. The results presented support the proposed hypothesis of transport using OLAND. Nitrifying activity in the sediment immediately recovered almost completely from prolonged oxygen-limited incubation when oxygen concentrations were increased.

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

Effect of repeated addition of nitrite to semi-continuous activated sludge reactors

To a semi-continuous lab-scale activated sludge system (SCAS), nitrite was dosed discontinuously, i.e. together with the feed. The nitrite was added at a concentration (50 mg N/l) which had been found earlier not to cause acute inhibition of the general running of the reactors. Repeated nitrite addition, however, exerted an inhibitory effect which was reflected in decreased removal efficiencies and was also expressed in decreases in total respiratory and nitrifying activity of 20% and 40%, respectively. The inhibition by nitrite was reversible as removal efficiencies improved after ceasing nitrite addition. The two consecutive test runs revealed that addition of nitrite gave rise to high amounts of dispersed cells and free-swimming protozoa. Moreover, DGGE patterns confirmed a shift in microbial community structure upon application of nitrite.

Vanin genes are clustered (human 6q22-24 and mouse 10A2B1) and encode isoforms of pantetheinase ectoenzymes

The mouse Vanin-1 molecule plays a role in thymic reconstitution following damage by irradiation. We recently demonstrated that it is a membrane pantetheinase (EC 3.56.1.-). This molecule is the prototypic member of a larger Vanin family encoded by at least two mouse (Vanin-1 and Vanin-3) and three human (VNN1, VNN2, VNN3) orthologous genes. We now report (1) the structural characterization of the human and mouse Vanin genes and their organization in clusters on the 6q22-24 and 10A2B1 chromosomes, respectively; (2) identification of the human VNN3 gene and the demonstration that the mouse Vanin-3 molecule is secreted by cells, and (3) that the Vanin genes encode different isoforms of the mammalian pantetheinase activity. Thus, the Vanin family represents a novel class of secreted or membrane-associated ectoenzymes. We discuss here their possible role in processes pertaining to tissue repair in the context of oxidative stress.

The ep -->e'p eta reaction at and above the S11(1535) baryon resonance

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Photoproduction of straight phi(1020) mesons on the proton at large momentum transfer

The cross section for straight phi meson photoproduction on the proton has been measured for the first time up to a four-momentum transfer -t = 4 GeV2, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. At low four-momentum transfer, the differential cross section is well described by Pomeron exchange. At large four-momentum transfer, above -t = 1.8 GeV2, the data support a model where the Pomeron is resolved into its simplest component, two gluons, which may couple to any quark in the proton and in the straight phi.

Pleiotropic effects of the melanocortin 1 receptor (MC1R) gene on human pigmentation

Variants of the melanocortin 1 receptor (MC1R) gene are common in individuals with red hair and fair skin, but the relative contribution to these pigmentary traits in heterozygotes, homozygotes and compound heterozygotes for variants at this locus from the multiple alleles present in Caucasian populations is unclear. We have investigated 174 individuals from 11 large kindreds with a preponderance of red hair and an additional 99 unrelated redheads, for MC1R variants and have confirmed that red hair is usually inherited as a recessive characteristic with the R151C, R160W, D294H, R142H, 86insA and 537insC alleles at this locus. The V60L variant, which is common in the population may act as a partially penetrant recessive allele. These individuals plus 167 randomly ascertained Caucasians demonstrate that heterozygotes for two alleles, R151C and 537insC, have a significantly elevated risk of red hair. The shade of red hair frequently differs in heterozygotes from that in homozygotes/compound heterozygotes and there is also evidence for a heterozygote effect on beard hair colour, skin type and freckling. The data provide evidence for a dosage effect of MC1R variants on hair as well as skin colour.

The influence of donated gametes on the incidence of hypertensive disorders of pregnancy

Pregnancies achieved from oocyte, sperm or embryo donation are unique, since they have resulted from donor gametes that are immunologically foreign to the mother. Thus, studying the obstetric outcome of such pregnancies may shed some light on the pathophysiology of preeclampsia, particularly in women conceiving with donated embryos, since the entire fetal genome is allogenic in these pregnancies. In this retrospective cohort study, a total of 144 women were studied. Of these, 72 were infertility patients who had conceived as a result of sperm, ovum or embryo donation and the other 72 women were age- and parity-matched control patients who became pregnant with their own gametes, either spontaneously, or following intrauterine insemination with their partner's spermatozoa. Study patients were divided into three groups depending on the origin of the donated gametes. Group 1 consisted of pregnancies achieved by intrauterine insemination with washed donor spermatozoa (n = 33). Group 2 included women who conceived using donated oocytes (n = 27) and group 3 consisted of women who conceived as a result of embryo donation (n = 12). The incidence of pregnancy-induced hypertension in the donated gametes study group was 12.5% (9/72) compared with 2.8% (2/72) in the control group. In addition, pre-eclampsia was diagnosed in 18.1% (13/72) of the donated gametes study group compared to 1.4% (1/72) in the age- and parity-matched controls. The increased incidence of gestational hypertension in pregnancies resulting from donated gametes gives evidence for a maternal genetic component, with an equally strong fetal influence, in the complicated aetiology of gestational hypertension, and pre-eclampsia in particular.

The measurement of blood pressure: sitting or supine, once or twice?

In 166 patients attending a hypertension review clinic, we compared supine and sitting blood pressure measurements and first and second measurements (1 min apart) in each position to determine whether any differences seen might have implications for the routine measurement of blood pressure in these patients, as a group or as individuals. Measurements were made with the Copal UA-251 semi-automated sphygmomanometer. In the group there was no significant difference between the first and the second diastolic measurements. The first systolic measurement was on average 3-4 mmHg higher than the second in both positions. Mean supine systolic pressures were 2-3 mmHg higher and diastolic pressures 2-3 mmHg lower than the corresponding sitting pressures. In individual subjects there were substantial disagreements between successive measurements in both positions and between positions. However, these differences would not have influenced blood pressure management in more than a few instances. We suggest that two measurements should routinely be taken, and the average recorded, particularly when the average exceeds 155/90 mmHg.

Binding of some primary aromatic amines to certain rat brain particulate fractions

The unsubstituted aromatic amines β-phenylethylamine and tryptamine, on addition to rat brain homogenates, were found to form relatively stable 'complexes' with certain particulate fractions. Similar particulate 'complexes' were found following intraventricular injections. As a result of this binding the recovery of small quantities of these amines added to brain homogenates was variable and low when compared to other tissue homogenates. Although p-tyramine formed similar 'complexes' both the strength and extent of the binding was much reduced. Subcellular fractionation revealed that β-phenylethylamine, tryptamine, and p-tyramine were associated with a myelin and synaptosomal fraction.