Offline Peptide Fractionation and Parallel Reaction Monitoring MS for the Quantitation of Low-Abundance Plasma Proteins

Mass spectrometry (MS)-based protein quantitation is an attractive means for research and diagnostics due to its high specificity, precision, sensitivity, versatility, and the ability to develop multiplexed assays for the "absolute" quantitation of virtually any protein target. However, due to the large dynamic range of protein concentrations in blood, high abundance proteins in blood plasma hinder the detectability and quantification of lower-abundance proteins which are often relevant in the context of different diseases. Here we outline a streamlined method involving offline high-pH reversed-phase fractionation of human plasma samples followed by the quantitative analysis of specific fractions using nanoLC-parallel reaction monitoring (PRM) on a Q Exactive Plus mass spectrometer for peptide detection and quantitation with increased sensitivity. Because we use a set of synthetic peptide standards, we can more efficiently determine the precise retention times of the target peptides in the first-dimensional separation and specifically collect eluting fractions of interest for the subsequent targeted MS quantitation, making the analysis faster and easier. An eight-point standard curve was generated by serial dilution of a mixture of previously validated unlabeled ("light") synthetic peptides of interest at known concentrations. The corresponding heavy stable-isotope-labeled standard (SIS) analogues were used as normalizers to account for losses during sample processing and analysis. Using this method, we were able to improve the sensitivity of plasma protein quantitation by up to 50-fold compared to using nanoLC-PRM alone.

Early Prediction of COVID-19 Patient Survival by Targeted Plasma Multi-Omics and Machine Learning

The recent surge of coronavirus disease 2019 (COVID-19) hospitalizations severely challenges healthcare systems around the globe and has increased the demand for reliable tests predictive of disease severity and mortality. Using multiplexed targeted mass spectrometry assays on a robust triple quadrupole MS setup which is available in many clinical laboratories, we determined the precise concentrations of hundreds of proteins and metabolites in plasma from hospitalized COVID-19 patients. We observed a clear distinction between COVID-19 patients and controls and, strikingly, a significant difference between survivors and nonsurvivors. With increasing length of hospitalization, the survivors' samples showed a trend toward normal concentrations, indicating a potential sensitive readout of treatment success. Building a machine learning multi-omic model that considers the concentrations of 10 proteins and five metabolites, we could predict patient survival with 92% accuracy (area under the receiver operating characteristic curve: 0.97) on the day of hospitalization. Hence, our standardized assays represent a unique opportunity for the early stratification of hospitalized COVID-19 patients.

Multiple reaction monitoring-mass spectrometry enables robust quantitation of plasma proteins regardless of whole blood processing delays that may occur in the clinic

Plasma is an important biofluid for clinical research and diagnostics. In the clinic, unpredictable delays—from minutes to hours—between blood collection and plasma generation are often unavoidable. These delays can potentially lead to protein degradation and modification and might considerably affect intact protein measurement methods such as sandwich enzyme-linked immunosorbent assays that bind proteins on two epitopes to increase specificity, thus requiring largely intact protein structures. Here, we investigated, using multiple reaction monitoring mass spectrometry (MRM-MS), how delays in plasma processing affect peptide-centric “bottom-up” proteomics. We used validated assays for proteotypic peptide surrogates of 270 human proteins to analyze plasma generated after whole blood had been kept at room temperature from 0 to 40 h to mimic delays that occur in the clinic. Moreover, we evaluated the impact of different plasma-thawing conditions on MRM-based plasma protein quantitation. We demonstrate that >90% of protein concentration measurements were unaffected by the thawing procedure and by up to 40-h delayed plasma generation, reflected by relative standard deviations (RSDs) of <30%. Of the 159 MRM assays that yielded quantitative results in 60% of the measured time points, 139 enabled a stable protein quantitation (RSD <20%), 14 showed a slight variation (RSD 20–30%), and 6 appeared unstable/irreproducible (RSD > 30%). These results demonstrate the high robustness and thus the potential for MRM-based plasma-protein quantitation to be used in a clinical setting. In contrast to enzyme-linked immunosorbent assay, peptide-based MRM assays do not require intact three-dimensional protein structures for an accurate and precise quantitation of protein concentrations in the original sample.

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Delays in whole blood processing often cannot be avoided in the clinic.

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These delays might affect measurements by intact protein assays such as ELISA.

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The impact on LC/MRM was evaluated using validated assays to quantify 270 proteins.

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>95% of the measured concentrations had RSDs <30% between delays of 0 to 40 h.

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Protein quantitation by LC/MRM-MS is robust against pitfalls in the clinical setting.

A multiplexed, automated immuno-matrix assisted laser desorption/ionization mass spectrometry assay for simultaneous and precise quantitation of PTEN and p110α in cell lines and tumor tissues

The PI3-kinase/AKT/mTOR pathway plays a central role in cancer signaling. While p110α is the catalytic α-subunit of PI3-kinase and a major drug target, PTEN is the main negative regulator of the PI3-kinase/AKT/mTOR pathway. PTEN is often down-regulated in cancer, and there are conflicting data on PTEN's role as breast cancer biomarker. PTEN and p110α protein expression in tumors is commonly analyzed by immunohistochemistry, which suffers from poor multiplexing capacity, poor standardization, and antibody crossreactivity, and which provides only semi-quantitative data. Here, we present an automated, and standardized immuno-matrix-assisted laser desorption/ionization mass spectrometry (iMALDI) assay that allows precise and multiplexed quantitation of PTEN and p110α concentrations, without the limitations of immunohistochemistry. Our iMALDI assay only requires a low-cost benchtop MALDI-TOF mass spectrometer, which simplifies clinical translation. We validated our assay's precision and accuracy, with simultaneous enrichment of both target proteins not significantly affecting the precision and accuracy of the quantitation when compared to the PTEN- and p110α-singleplex iMALDI assays (<15% difference). The multiplexed assay's linear range is from 0.6-20 fmol with accuracies of 90-112% for both target proteins, and the assay is free of matrix-related interferences. The inter-day reproducibility over 5-days was high, with an overall CV of 9%. PTEN and p110α protein concentrations can be quantified down to 1.4 fmol and 0.6 fmol per 10 μg of total tumor protein, respectively, in various tumor tissue samples, including fresh-frozen breast tumors and colorectal cancer liver metastases, and patient-derived xenograft (PDX) tumors.

Performance Assessment of a 125 Human Plasma Peptide Mixture Stored at Room Temperature for Multiple Reaction Monitoring-Mass Spectrometry

Synthetic peptides are a critical requirement for the development and application of targeted mass spectrometry (MS)-based assays for the quantitation of proteins from biological matrices. Transporting synthetic peptides on dry ice from one laboratory to another is costly and often difficult because of country-specific import and export regulations. Therefore, in this study, we assessed the impact of leaving a lyophilized mixture consisting of 125 peptides at room temperature for up to 20 days, and we assessed the effect on the quantitative performance of multiple reaction monitoring-MS (MRM-MS) assays. The findings suggest that there are no significant differences in the MRM-MS results for the time points assessed in this study (up to 20 days). All the calibration curves and quality control (QC) samples met the acceptance criteria for precision and accuracy (raw data are available via the public MS data repository PanoramaWeb, identifier: /MRM Proteomics/2020_BAK125_RT). The number of endogenous proteins quantifiable across five plasma samples was consistently between 87 and 99 out of 125 for all time points. Moreover, the coefficients of variation (CVs) calculated for the majority of peptide concentrations across all samples and time points were <5%. In addition, a lyophilized peptide mixture was transported from Canada to Iceland without dry ice. The results showed that there was no significant difference in the quantitative performance, with the determined concentrations of most proteins in the samples falling within 30% between the analyses performed on the same three plasma samples in Iceland and those in Canada. Overall, a comparison of the results obtained in Canada and in Iceland indicated that the peptides were stable under the conditions tested and also indicated that shipping lyophilized peptide mixtures without dry ice, but in the presence of sufficient desiccant material, could be a feasible option in cases where transport difficulties may arise or dry-ice sublimation may occur.

Face tuning in female and male individuals with depression

Introduction

The current COVID-19 pandemic brings social isolation to our daily lives that may elevate depression. The impact of major depressive disorder (MDD) on social cognitive functioning is far from understood, but essential for prevention and treatment of this neuropsychiatric condition.

Objectives

Our aim was to examine (i) whether face tuning is lower in depression; and (ii) how it is related to other cognitive abilities (such as perceptional organization). Furthermore, we intended to clarify gender impact on face tuning in MDD, as twice more females are affected.

Methods

Using a recently developed paradigm, the Face-n-Food task, we examined face tuning in 26 patients with MDD and 26 person-by-person matched controls. The advantage of non-face images is that its single elements do not promote face processing.

Results

Strikingly, MDD individuals showed intact face tuning. As sex ratio in our patient sample was about 2:1 (as in MDD population in general), we recruited additional male patients and found that MDD male patients were as good as female patients. Yet, while face tuning in MDD patients showed a significant correlation with perceptual organization abilities, in controls, it was linked with social cognition.

Conclusions

The outcome suggests that the origins of aberrant social functioning in MDD lie in maladaptive cognitive schemas rather than in a lack of sensitivity towards social signals per se. To elucidate neural circuits involved in face tuning in MDD, a magnetoencephalography (MEG) study with the Face-n-Food images is currently under progress.

Disclosure

No significant relationships.

Abstract B21: Protein quantitation assays for Akt, PI3K p110α, and PTEN to assess PI3K pathway activity in tumor tissue

Introduction: Many clinical trials for inhibitors targeting the PI3K pathway now include genetic screening of tumors to try to select probable treatment responders. Genetic testing identifies some relevant mutations, but this approach does not address many mechanisms of PI3K pathway regulation. Epigenetic changes and post-translational modifications may increase pathway activity without any detectable DNA mutation. Where mutations are detected, mutated proteins may not be expressed or may be quickly degraded. Direct measurement of oncogenic proteins may therefore offer more useful molecular profiles for characterizing cancer-driving alterations and matching patients with appropriate treatments.

Purpose: The purpose of this study was to develop and implement protein quantitation assays to accurately assess PI3K pathway activity in tumors, as a means of matching patients with targeted cancer treatments.

Methods: Protein extracted from tumor tissue lysate is subjected to proteolytic digestion to generate proteotypic peptides used for protein quantitation. Synthetic stable isotope-labeled peptides are added to the digest as an internal standard, after which the target peptides are immuno-enriched with antibodies coupled to magnetic beads. MS analysis is then performed by either eluting peptides for measurement with liquid chromatography multiple reaction monitoring tandem MS (LC-MRM-MS/MS) or by spotting beads onto a plate for matrix-assisted laser desorption MS (MALDI-MS). External calibration curves are used for accurate quantitation.

Results: We developed and implemented MS-based methods to determine the concentration of PI3K pathway proteins in tumor samples. The developed methods enable precise and reproducible quantitation of Akt1, Akt2, PI3K P110α, and PTEN. We were able to distinguish and quantify specific isoforms, including phospho-Akt1 (Ser473), phospho-Akt2 (Ser474), and mutant-Akt (E17K). Endogenous protein levels were quantified in cell lines, fresh-frozen tumor samples, and formalin-fixed, paraffin embedded tumor tissue. 10 μg of protein extract per analyte was sufficient for quantitation. Subsets of assays could be multiplexed through simultaneous or sequential enrichment without compromising assay performance.

Novel Aspect: The multiplexing of immuno-MALDI assays through sequential enrichment and the immuno-MRM-MS assays for PTEN and mutant Akt represent new developments. Recent adoption of monoclonal antibodies for Akt1 will facilitate this assay's translation to a clinical setting.

Conclusions: This panel of quantitative proteomics assays enables comprehensive PI3K pathway assessment in tumor tissues. Previously collected genetically screened tumor samples were obtained with patient consent (as approved by the Jewish General Hospital Research Ethics Committee). Samples will be analyzed to assess PI3K pathway activity and determine its correlation to clinical features and response to PI3K-targeted treatments.

Note: This abstract was not presented at the conference.

Citation Format: Constance A. Sobsey, Robert Popp, Sahar Ibrahim, Bjoern C Froehlich, Adriana Aguilar-Mahecha, Mark Basik, Gerald Batist, Christoph Borchers. Protein quantitation assays for Akt, PI3K p110α, and PTEN to assess PI3K pathway activity in tumor tissue [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr B21.

Systematic Optimization of the iMALDI Workflow for the Robust and Straightforward Quantification of Signaling Proteins in Cancer Cells

PURPOSE

Immuno-MALDI (iMALDI) combines immuno-enrichment of biomarkers with MALDI-MS for fast, precise, and specific quantitation, making it a valuable tool for developing clinical assays. iMALDI assays are optimized for the PI3-kinase signaling pathway members phosphatase and tensin homolog (PTEN) and PI3-kinase catalytic subunit alpha (p110α), with regard to sensitivity, robustness, and throughput. A standardized template for developing future iMALDI assays, including automation protocols to streamline assay development and translation, is provided.

EXPERIMENTAL DESIGN

Conditions for tryptic digestion and immuno-enrichment (beads, bead:antibody ratios, incubation times, direct vs. indirect immuno-enrichment) are rigorously tested. Different strategies for calibration and data readout are compared.

RESULTS

Digestion using 1:2 protein:trypsin (wt:wt) for 1 h yielded high and consistent peptide recoveries. Direct immuno-enrichment (antibody-bead coupling prior to antigen-enrichment) yielded 30% higher peptide recovery with a 1 h shorter incubation time than indirect enrichment. Immuno-enrichment incubation overnight yielded 1.5-fold higher sensitivities than 1 h incubation. Quantitation of the endogenous target proteins is not affected by the complexity of the calibration matrix, further simplifying the workflow.

CONCLUSIONS AND CLINICAL RELEVANCE

This optimized and automated workflow will facilitate the clinical translation of high-throughput sensitive iMALDI assays for quantifying cell-signaling proteins in individual tumor samples, thereby improving patient stratification for targeted treatment.

Abstract P4-10-20: Protein quantitation assays for AKT and PTEN to better understand sensitivity and resistance of breast cancer patients to treatment with AKT inhibitor capivasertib

Context: The PI3K/AKT/PTEN pathway is frequently aberrantly activated in breast cancer (BC) and involved in resistance to hormonal therapy. Multiple drugs targeting this pathway are approved or in development, including the pan-AKT inhibitor capivasertib (AZD5363). Early phase studies of capivasertib as monotherapy for solid cancers (e.g. NCT01226316, NCT01625286) have used genetic testing to select patients considered most likely to respond based on AKT1, PIK3CA or PTEN mutations. However, not all selected patients responded. Randomised phase 2 studies on Capivasertib as combination treatment showed the importance of context; a more pronounced response in combination with paclitaxel was seen in TNBC patients whose tumors harboured an alteration on AKT1, PIK3CA or PTEN (Schmid et al. ASCO 2018), whereas the same combination in ER+ HER2- advanced/metastatic BC patients did not show a clinical benefit in the overall population nor in the PIK3CA-mutation subgroup (Turner et al. Ann Oncol 2019). The combination with fulvestrant demonstrated an effect in unselected ER+ HER2- advanced BC patients resistant to aromatase inhibitors irrespective of PIK3CA mutations or PTEN IHC status (Jones et al. ASCO 2019). DNA-based assays also have the limitation that potential responders may be missed, e.g., tumors with epigenetic pathway activation but no detectable mutations. Techniques such as IHC and Western Blot (WB) lack the sensitivity, reproducibility and standardization required to precisely quantify these proteins. We hypothesize that precise mass spectrometry (MS)-based methods may facilitate a better understanding of sensitivity and resistance to inhibitors of the PI3K/AKT pathway in future studies.

Methods: Protein extracted from tumor tissue lysate is subjected to proteolytic digestion to generate proteotypic peptides used for protein quantitation. Synthetic stable isotope-labeled peptides are added to the digest as an internal standard, after which the target peptides are immuno-enriched with antibodies coupled to magnetic beads. MS analysis is performed by either eluting peptides for measurement with liquid chromatography multiple reaction monitoring tandem MS (LC-MRM-MS/MS) or by spotting beads onto a plate for matrix-assisted laser desorption/ionization MS (MALDI-MS). Calibration curves enable accurate quantitation. A new method for PTEN was applied to 13 breast cancer PDXs. Results were compared to IHC and WB. In a retrospective study, we are applying these methods to test samples from HR+ metastatic breast or gynecological cancer patients (n=25 with PIK3CA-mutations, capivasertib monotherapy; n=26 with PTEN alterations, capivasertib + fulvestrant; n=9 with no PIK3CA, AKT1 or PTEN mutations, not receiving capivasertib). AKT and PTEN quantitation data will be analyzed for a relationship to treatment response as determined by RECIST guidelines (NCT01226316).

Results: We validated MS methods to precisely and reproducibly determine AKT and PTEN concentrations in tumor samples. AKT concentrations varied significantly between mutation-positive tumor samples (AKT1: 0.06-0.45, AKT2: 0.05-0.20 fmol/µg total protein). Significant phosphorylation of AKT1-Ser473 or AKT2-Ser474 was observed in 2 out of 17 tested samples. At least 1 mutation-negative sample had a high AKT1 concentration of 0.42 fmol/ug total protein. PTEN concentrations from PDXs were consistent across biological replicates and agreed with IHC and WB. Furthermore, we were able to detect and quantify PTEN from 3 samples that were negative by IHC and/or WB.

Conclusion: AKT and PTEN quantitative proteomics assays have the potential to enable more accurate assessment of PI3K/AKT/PTEN pathway activation in tumor tissues from patients treated with inhibitors of this key pathway.

Citation Format: Sahar Ibrahim, Constance A Sobsey, Robert Popp, René P. Zahedi, Gerald Batist, Christoph H. Borchers. Protein quantitation assays for AKT and PTEN to better understand sensitivity and resistance of breast cancer patients to treatment with AKT inhibitor capivasertib [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-10-20.

Determination of the concentration range for 267 proteins from 21 lots of commercial human plasma using highly multiplexed multiple reaction monitoring mass spectrometry

Multiple reaction monitoring (MRM) is a key tool for biomarker validation and the translation of potential biomarkers into the clinic.

THE RESTLESS LEGS SYNDROME (REVIEW)

The restless legs syndrome (RLS), also known as Willis-Ekbom disease, is a common sleep related neurological disorder with prevalence between 1 and 10%, increasing with age. Women are more frequently affected than men. RLS is characterized by an urge to move the legs accompanied by uncomfortable and unpleasant sensations in the legs, worsening of complaints during periods of rest, improvement by movement and an increase of symptoms in the evening or at night. In addition, affected patients may also suffer from severe sleep disorders and negative effects on daily activities. There is often a history of RLS among first-degree relatives, especially with the primary form. Among other, comorbidities or causal factors are iron deficiency, terminal renal insufficiency, pregnancy, polyneuropathy, or psychotropic drugs. The etiology of primary (idiopathic) RLS has not been clarified yet; however, genetic factors and dysfunctional dopaminergic neurotransmission as well as alterations of central iron metabolism play an important role. In addition to non-pharmacological treatment such as lifestyle modifications or behavioral strategies, levodopa, dopamine agonists, or anticonvulsants are effective. Opioids may be used in otherwise refractory forms. In the case of secondary or comorbid RLS, treatment of the underlying disease is necessary.

Abstract LB-177: Quantification of cell signaling proteins by immuno-MALDI

Introduction. To improve cancer patient stratification and overcome the drawbacks of currently used approaches to assess signaling pathway proteins, we set out to develop immuno-matrix assisted laser ionization/desorption (iMALDI) assays combined with a phosphatase-based phosphopeptide quantitation (PPQ) approach to measure PI3K/AKT/mTOR pathway activity. Specifically, we targeted the C-terminal tryptic peptides of AKT1 and AKT2 due to their involvement in full kinase activation.

Methods. Following trypsin digestion of cell lysate, stable isotope-labeled standard (SIS) peptides are added. After splitting the solution, one aliquot is treated with phosphatase. Bead-coupled antibodies enrich the non-phosphorylated target peptides, which are washed and spotted onto a MALDI plate, and acidic MALDI matrix elutes the peptides. The resulting light/heavy ratios of both aliquots allow the calculation of protein expression levels and peptide phosphorylation stoichiometry.

Results. The iMALDI assays were validated for linear range and accuracy, as well as interference screening, requiring only ~50 µg of total cell or tissue lysate protein to quantify both AKT1 and AKT2 expression levels and phosphorylation stoichiometry. CVs of technical replicates were found to consistently be below 10%. We were able to quantify AKT1 and AKT2 from various cell lines and fresh frozen tumor samples, including SW480 and HCT116 colon cancer cell lines, MDA-MB-231 breast cancer cells, and colon cancer and breast cancer tumor lysates. Further, a direct comparison of matched fresh frozen and formalin-fixed paraffin-embedded (FFPE) tissues showed that the expression levels and phosphorylation stoichiometry quantified differ depending on the tissue preservation method, and that phosphorylation stoichiometries above 30% occur in only a small subset of samples. A direct comparison of four pairs of normal and adjacent tumor tissues showed elevated AKT1 phosphorylation stoichiometry of ~40% in a colorectal cancer liver metastasis, and significantly elevated AKT1 (3.6-fold) and AKT2 (2.2-fold) expression levels in a surgical breast tumor sample.

Future directions. In a next step, patient-derived mouse xenograft tissue samples, collected after specific drug treatment, will be analyzed, and the AKT results will be correlated to genomic data to answer the hypothesis whether the AKT expression levels and phosphorylation stoichiometries correlate with response to treatment.

Citation Format: Robert Popp, René P. Zahedi, André LeBlanc, Yassene Mohammed, Adriana Aguilar-Mahecha, Oliver Pötz, Mark Basik, Gerald Batist, Christoph H. Borchers. Quantification of cell signaling proteins by immuno-MALDI [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-177.

How iMALDI can improve clinical diagnostics

Protein mass spectrometry (MS) is an indispensable tool to detect molecular signatures that can be associated with cellular dysregulation and disease.

Peptide and Protein Quantification Using Automated Immuno-MALDI (iMALDI)

Mass spectrometry (MS) is one of the most commonly used technologies for quantifying proteins in complex samples, with excellent assay specificity as a result of the direct detection of the mass-to-charge ratio of each target molecule. However, MS-based proteomics, like most other analytical techniques, has a bias towards measuring high-abundance analytes, so it is challenging to achieve detection limits of low ng/mL or pg/mL in complex samples, and this is the concentration range for many disease-relevant proteins in biofluids such as human plasma. To assist in the detection of low-abundance analytes, immuno-enrichment has been integrated into the assay to concentrate and purify the analyte before MS measurement, significantly improving assay sensitivity. In this work, the immuno- Matrix-Assisted Laser Desorption/Ionization (iMALDI) technology is presented for the quantification of proteins and peptides in biofluids, based on immuno-enrichment on beads, followed by MALDI-MS measurement without prior elution. The anti-peptide antibodies are functionalized on magnetic beads, and incubated with samples. After washing, the beads are directly transferred onto a MALDI target plate, and the signals are measured by a MALDI-Time of Flight (MALDI-TOF) instrument after the matrix solution has been applied to the beads. The sample preparation procedure is simplified compared to other immuno-MS assays, and the MALDI measurement is fast. The whole sample preparation is automated with a liquid handling system, with improved assay reproducibility and higher throughput. In this article, the iMALDI assay is used for determining the peptide angiotensin I (Ang I) concentration in plasma, which is used clinically as readout of plasma renin activity for the screening of primary aldosteronism (PA).

GSTM1, GSTT1 and GSTP1 Genetic Variants in Multiple Urologic Cancers

INTRODUCTION

Glutathione S-transferases (GSTs) are phase 2 enzymes responsible for catalyzing the biotransformation of a wide variety of electrophilic compounds, having a crucial role in the detoxification of active metabolites of procarcinogens produced by phase 1 reactions, tying them to glutathione and promoting their excretion in the urine.

OBJECTIVES

we evaluated GSTM1, GSTT1 and GSTP1 genotypes in patients diagnosed with multiple malignancies, of which at least one was found in the prostate, bladder or kidney.

MATERIALS AND METHODS

GSTM1, GSTT1 and GSTP1 genotypes were genetically assessed in 34 patients with multiple urologic cancers and 23 patients with urologic cancer associated with another type of cancer.

RESULTS

in the group of patients with multiple urologic cancers, GSTT1 null genotype was found in 26.4% of patients compared to 0% in controls, 82.35 % of patients and 47% of witnesses carried at least one GSTM1 or GSTT1 null genotype, and in the group with different cancers, GSTM1 null genotype was found in 52.1% of patients compared to 4.3% witnesses in the control group; GSTT1 null genotype was found in 34.7% of patients compared to 4.3% of witnesses, atleast one GSTM1 or GSTT1 null genotype was found in 73.9% of patients compared to 8.6% of controls.

CONCLUSIONS

GSTT1 null genotype is a risk factor for patients with more primitive urologic malignancies (bladder, prostate and kidney); GSTM1 or GSTT1 null genotype is more frequent in patients with multiple urologic tumors; GSTM1 and GSTT1 null genotypes are risk factors in patients with different types of cancer, with at least one affecting the urinary system.

GSTM1, GSTT1 and GSTP1 in patients with multiple breast cancers and breast cancer in association with another type of cancer

INTRODUCTION

breast cancer has the highest incidence in women.Glutathione S-transferases (GSTs) are a large group of enzymes involved in the metabolism of xenobiotics. The members of this gene superfamily are involved in the development of multiple cancers.

OBJECTIVES

the aim of the study was to see whether the GSTM1, GSTT1 and GSTP1 genetic polymorphisms are risk factors for patients diagnosed with multiple malignancies, of which at least one is located in the breast.

MATERIALS AND METHODS

in the period between 2005 and 2012,of the 520 patients diagnosed with breast cancer, 69 had multiple primitive malignant tumors, of which at least one was localized in the breast. The research on GSTM1, GSTT1 and GSTP1 genotypes consisted of 59 patients diagnosed with multiple breast cancers or with breast cancer in association with another type of cancer, compared with a group of healthy controls.

RESULTS

in the subgroup of patients with breast cancer in association with another type of cancer, the GSTM1 null genotype was present in 61.2% of patients, compared to 29% of controls; the subgroup of metachronous breast cancers, the presence of any of the GSTT1 or GSTM1 null genotypes was statistically significantly different from that of controls (65.2%vs. 28.5%); in the subgroup with synchronous cancers, the GSTM1 null genotype was found in 66.6% of patients compared to 9% for the controls, and the presence of any null genotype (GSTM1 and GSTT1) was also statistically significant in the case group.

CONCLUSIONS

the GSTM1 null genotype is a risk factor for synchronous breast cancers and for breast cancer associated with extramammary cancer; the presence of null genotypes(GSTM1 or GSTT1) is a risk factor for multiple breast cancer(bilateral or synchronous); the GSTT1 null genotype and the heterozygous variant allele (Ile105Val) and homozygous variant allele (Val105Val) of GSTP1 are not risk factors for the cases studied.

Development and evaluation of an immuno-MALDI (iMALDI) assay for angiotensin I and the diagnosis of secondary hypertension

Plasma renin activity (PRA) is an essential analytical tool for screening and diagnosis of secondary forms of hypertension. Typically, PRA is measured by competitive radioimmunoassay, but there are significant drawbacks to this technique including non-specificity, long analysis times, narrow calibration range, and the requirement for radionucleotides. In this paper, we report a method for plasma renin activity determination by immuno-MALDI mass spectrometry detection. This method overcomes the issues of non-specificity and long analytical times present with RIA, and does not require the use of radionucleotides. As an initial methodological evaluation, plasma renin activity results obtained by radioimmunoassay, LC/ESI-MS/MS, and immuno-MALDI on 64 samples from an outpatient primary aldosteronism screening program have been compared. A strong correlation was found between immuno-MALDI and radioimmunoassay (R2 = 0.9412, 62/64 within the 95% CI of the Bland-Altman plot), and iMALDI and LC/ESI-MS/MS (R2 = 0.9471, 62/64 within the 95% CI of the Bland-Altman plot). Technical replicates showed a 4.8% CV, while inter- and intra-day replicates showed CVs of 17.3% and 17.2% respectively. We have developed an assay capable of measuring PRA without the use of radionucleotides. This immuno-MALDI approach affords the specificity of MS while avoiding the long analytical run times and technical problems associated with HPLC. With the use of robotic sample preparation to optimize precision, this assay should be adaptable to clinical environments.

Impact of daytime sleepiness on rehabilitation outcome in the elderly

Daytime sleepiness (DS) is associated with poor health, impaired physical functioning, as well as somatic and psychiatric morbidity. The impact of DS on functional outcome in the elderly is unknown. We investigated whether observed daytime sleepiness in geriatric patients with moderate to severe functional impairment was associated with functional clinical outcomes. We addressed the issue by determining the impact of observed daytime sleepiness, by means of the Essener Questionnaire of Age and Sleepiness (EQAS), on improvement in functional status - measured by the Barthel ADL Index - among disabled geriatric in-patients. We included 129 patients, 28 (22%) were male and 101 (78%) were female. Sleepiness according to EQAS scale was absent in 27 (21%) patients, mild in 71 (55%) patients and moderate to severe in 31 (24%) patients. The three patient groups did not differ in the Barthel ADL Index (BI) on admission or co-morbid conditions. Geriatric treatment was comparable across groups. Improvement in the BI of at least 1 standard deviation (SD) occurred in 23/27 (85%) of subjects without sleepiness, in 53/71 (75%) of subjects with mild to moderate sleepiness and in 15/31 (44%) of subject with severe sleepiness (p < 0.01). BI increased at least 2 SD in 20/27 (74%), 38/71 (54%) and 11/31 (35%) individuals, respectively (p < 0.02). We conclude that the daytime sleepiness predicts a poorer functional recovery rate in older patients during geriatric in-hospital rehabilitation. Furthermore, we found a significant association and a dose response relationship between severity of daytime sleepiness and improvement in Barthel ADL Index.

Prevalence of the c.35delG and p.W24X mutations in the GJB2 gene in patients with nonsyndromic hearing loss from North-West Romania

OBJECTIVE

In Central and South-Eastern European countries, the most frequent mutation types responsible for congenital nonsyndromic sensorineural hearing loss (NSHL) are c.35delG and p.W24X (15-55.8% and 2.5-4.3%, respectively). The aim of the study was to determine for the first time in Romania the prevalence of c.35delG and p.W24X mutations in patients with NSHL.

MATERIAL

75 unrelated children with NSHL from Transylvania (North-West Romania).

METHODS

a. Audiological examination (otoscopy, tympanogram, acoustic otoemission and tonal audiogram or auditory evoked potentials); b. detection of the c.35delG (semi-nested-PCR, RFLP and ARMS-PCR analysis) and p.W24X (ARMS-PCR analysis) mutations.

RESULTS

Audiological examination allowed the diagnosis of hearing loss of various degrees: moderate in 8 patients (10.7%), severe in 14 cases (18.7%), profound in 53 patients (70.6%). The number of reported mutation cases as against the number of alleles indicates a 33.3% frequency rate for c.35delG mutation and respectively 5.3% for p.W24X mutation. All 22 patients with 35delG/c.35delG genotype (19 patients), c.35delG/p.W24X genotype (2 patients) or p.W24X/p.W24X genotype (1 patient) presented profound/severe hearing loss.

CONCLUSION

Our study confirms that the frequency rate of the two mutations analyzed in patients with NSHL from North-West Romania is comparable to that seen in other Central and South-Eastern European countries. The homozygote or compound heterozygote states represent a major risk factor for profound or severe deafness. Audiological screening in newborns and genetic testing in confirmed congenital hypoacusis cases are compulsory for early therapeutic intervention (hearing prosthesis or cochlear implant) and genetic counselling.

Feasibility of the Epworth Sleepiness Scale in a sample of geriatric in-hospital patients

Excessive daytime sleepiness (EDS) is a major health concern in geriatric patients. EDS affects quality of life, daytime function, and mortality. The Epworth Sleepiness Scale (ESS) is a standard tool for the assessment daytime sleepiness, but the feasibility of the ESS has never been investigated in elderly subjects. We applied the ESS to a random sample of geriatric in-hospital patients. The aim of the study was to reveal the frequency and the risk factors for processing failure of the ESS in geriatric patients. 458 patients with a mean age of 82+/-8 years were included. One hundred sixty six (36%) completed the ESS, 118 (28%) patients had omissions of items, and 174 (38%) patients were unable to respond to any item. Completion of the ESS correlated significantly with age, disability, dementia, impairment of vision, and hearing. Omitted items were related to mobility and activities outside the house. Logistic regression analysis with completed ESS as a dependent variable revealed that dementia, disability, heart failure, and COPD were independent and significant risk factors for processing failure. The majority of patients of a geriatric unit are unable to complete the ESS. Since EDS is a frequent finding with a negative impact on health, the development of a reliable and valid tool for the assessment of EDS in elderly subjects is needed.

Positron emission tomography findings in obstructive sleep apnea patients with residual sleepiness treated with continuous positive airway pressure

Despite sufficient continuous positive airway pressure (CPAP) therapy, some patients with the obstructive sleep apnea syndrome (OSAS) still suffer from excessive daytime sleepiness (EDS). In some of them, no cause of the persistence of EDS can be found. Brain damage due to nocturnal hypoxemia is a potential cause for this unclear persistent sleepiness (UPS). This study was done to evaluate this hypothesis. Patients with UPS were identified among the OSAS patients, who came for a CPAP therapy checkup to our sleep laboratory. UPS was recognized when no explanation for persistent EDS could be yielded by standard diagnostic procedures. Out of 167 patients under CPAP therapy 13 had UPS. To investigate the brain morphology, positron emission tomography (PET) scanning with the tracer fluorine-18 fluorodeoxyglucose (FDG), called FDG-PET, were performed in 7 of the UPS patients. Abnormal PET findings were concentrated in frontal area (found in 4 patients). The frontal abnormality seems to distinguish the OSAS patients with UPS from the whole OSAS population, examined in previous studies.

Outcomes of CPAP treatment in a sleep laboratory specialized in neuropsychiatry

The rapidly increasing number of sleep laboratories implicates their specialization into various fields of sleep medicine. In our sleep laboratory that specializes in neuropsychiatry, patients with the symptoms typical for the obstructive sleep apnea/hypopnea syndrome (OSAHS) were routinely redirected to a local respiratory clinic. Some patients, however, admitted to our center for other reasons revealed OSAHS in nocturnal polysomnography. The purpose of this retrospective study was to assess the outcome of CPAP in treating the sleepiness in this group of patients. Our material consisted of 36 patients who started CPAP therapy due to OSAHS diagnosed in our laboratory in the year 2000 and who came for a routine checkup in 2001. The sleepiness was assessed by using the Epworth Sleepiness Scale (ESS). After CPAP, the mean group ESS score decreased from 10.9 +/-4.4 to 8.5 +/-4.3 points (P<0.01). Some patients showed, however, persisting excessive sleepiness (PTS) after CPAP, defined as ESS >or=12. We overviewed the documentation of those patients in search for the possible causes of PTS. We identified the following causes: narcolepsy - 1 patient, insufficient CPAP pressure - 1 patient, low CPAP compliance, fewer than 2 h/night, - 2 patients. In 5 other patients we found CPAP compliance to be between 2.0 and 4.5 h/night, which is less likely to be the cause of PTS. In 1 patient no cause was identified. Our patients showed relatively mild sleepiness before CPAP and only a slight improvement under CPAP. The CPAP noncompliance seems the most prevailing reason for CPAP failure, but in some patients the cause of PTS could not be unraveled by using standard diagnostic tools and some additional measures are to be employed to resolve the issue.

Hyperthyroidism enhances endothelium-dependent relaxation in the rat renal artery

OBJECTIVE

Hyperthyroidism has pronounced effects on vascular function and endothelium-dependent relaxation. The aim of the present study was to identify mechanisms underlying hyperthyroidism-induced alterations in endothelial function in rats.

METHODS

Animals were subjected to either a single injection (36 h) or 8 weeks treatment with the thyroid hormone triiodothyronine (T3, i.p.). Vascular reactivity and agonist-induced hyperpolarization were studied in isolated renal arteries. Endothelial nitric oxide (NO) synthase expression and cyclic AMP accumulation were determined in aortic segments.

RESULTS

Endothelium-dependent relaxations to acetylcholine (ACh) were enhanced by T3 36 h after injection and after treatment for 8 weeks. Thirty-six hours after T3 application, relaxation mediated by the endothelium-derived hyperpolarizing factor (EDHF) and by endothelium-derived NO were significantly enhanced. After 8 weeks treatment with T3, however, EDHF-mediated relaxation was impaired, whereas NO-mediated relaxation remained enhanced. KCl- and ACh-induced hyperpolarizations were more pronounced in arteries from rats treated with T3 for 36 h compared to control, whereas in arteries from rats treated with T3 for 8 weeks both responses were attenuated. In rats treated for 36 h, vascular cyclic AMP levels were enhanced in the aorta and inhibition of protein kinase A attenuated EDHF-mediated relaxations of the renal artery without affecting responses in arteries from the control group. In the aorta from rats treated with T3 for 8 weeks, the expression of the endothelial NO synthase was markedly up-regulated (463+/-68%).

CONCLUSIONS

These data indicate that short-term treatment with T3 increases endothelium-dependent relaxation, most probably by increasing vascular cyclic AMP content. Following treatment with T3 for 8 weeks, expression of the endothelial NO synthase was enhanced. During this phase, NO appears to be the predominant endothelium-derived vasodilator.

The extracellular regulated kinases (ERK) 1/2 mediate cannabinoid-induced inhibition of gap junctional communication in endothelial cells

1. Cannabinoids are potent inhibitors of endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxations. We set out to study the mechanism underlying this effect and the possible role of cannabinoid-induced changes in intercellular gap junction communication. 2. In cultured endothelial cells, Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and the cannabinoid receptor agonist HU210, increased the phosphorylation of extracellular regulated kinases 1/2 (ERK1/2) and inhibited gap junctional communication, as determined by Lucifer Yellow dye transfer and electrical capacity measurements. 3. Delta(9)-THC elicited a pronounced increase in the phosphorylation of connexin 43, which was sensitive to PD98059 and U0126, two inhibitors of ERK1/2 activation. Inhibition of ERK1/2 also prevented the Delta(9)-THC-induced inhibition of gap junctional communication. 4. Delta(9)-THC prevented both the bradykinin-induced hyperpolarization and the nitric oxide and prostacyclin-independent relaxation of pre-contracted rings of porcine coronary artery. These effects were prevented by PD98059 as well as U0126. 5. In the absence of Delta(9)-THC, neither PD98059 nor U0126 affected the NO-mediated relaxation of coronary artery rings but both substances induced a leftward shift in the concentration - relaxation curve to bradykinin when diclofenac and N(omega)nitro-L-arginine were present. Moreover, PD98059 and U0126 prolonged the bradykinin-induced hyperpolarization of porcine coronary arteries, without affecting the magnitude of the response. 6. These results indicate that the cannabinoid-induced activation of ERK1/2, which leads to the phosphorylation of connexin 43 and inhibition of gap junctional communication, may partially account for the Delta(9)-THC-induced inhibition of EDHF-mediated relaxation. Moreover, the activation of ERK1/2 by endothelial cell agonists such as bradykinin, appears to exert a negative feedback inhibition on EDHF-mediated responses.

Cyclic stretch enhances the expression and activity of coronary endothelium-derived hyperpolarizing factor synthase

Endothelium-derived hyperpolarizing factor (EDHF) mediates NO/prostacyclin-independent relaxation in the coronary circulation. Because hemodynamic stimuli modulate endothelial gene expression and because coronary arteries are subjected to pronounced variations in vessel distension, we determined the effects of cyclic stretch on the expression and activity of the coronary EDHF synthase/cytochrome P450 (CYP) 2C8/9. In cultured porcine coronary and human umbilical vein endothelial cells, acute application of cyclic stretch (6%, 1 Hz, 10 minutes) elicited the generation of 8,9-epoxyeicosatrienoic acid (EET), 11,12-EET, and 14,15-EET. Prolonged stretch (4 to 36 hours) increased the expression of CYP 2C mRNA and protein 5- to 10-fold and was accompanied by a 4- to 8-fold increase in EET generation. A corresponding increase in CYP 2C mRNA and protein was also observed in pressurized segments of porcine coronary artery perfused under pulsatile conditions (8%, 1 Hz) for 6 hours. Although in cultured endothelial cells, cyclic stretch elicited the rapid activation of tyrosine kinases as well as Akt and the p38 mitogen-activated protein kinase, the mechanism by which cyclic stretch induces the expression of CYP 2C could not be elucidated, because inhibitors of these pathways induced CYP 2C expression in cells maintained under static conditions. These results have identified coronary EDHF synthase/CYP 2C as a novel mechanosensitive gene product in native and cultured endothelial cells. Because this enzyme generates both EETs and superoxide anions, this finding has wide-reaching implications for vascular homeostasis in conditions of manifest endothelial dysfunction.

The coronary endothelium-derived hyperpolarizing factor (EDHF) stimulates multiple signalling pathways and proliferation in vascular cells

In the present study we determined whether the endothelium-derived hyperpolarizing factor (EDHF), in addition to its acute effects on vascular tone, activates intracellular signalling pathways other than those associated with Ca2+-dependent K+ channels. EDHF was generated by rhythmic distension of porcine coronary arteries under conditions of combined nitric oxide (NO) synthase/cyclo-oxygenase blockade, and the EDHF-containing luminal incubate was applied to cultured human coronary endothelial or smooth muscle cells. In both cell types, the luminal incubate activated tyrosine kinases, the mitogen-activated protein (MAP) kinases, extracellular signal regulated kinases 1 and 2 (Erk1/2) and p38, as well as protein kinase B/Akt. The constituent responsible for Erk1/2 phosphorylation was identified as a cytochrome P450 (CYP) metabolite, as Erk1/2 activation was attenuated by pretreating the EDHF donor with the CYP 2C inhibitor sulfaphenazole as well as by CYP 2C antisense oligonucleotides. Erk1/2 phosphorylation in detector cells was also observed following the transfer of supernatant from cultured endothelial cells treated with the CYP inducer beta-naphthoflavone. The CYP 2C product 11,12-epoxyeicosatrienoic acid (11,12-EET) also activated tyrosine kinases, Erk1/2 and p38 MAP kinase. Overexpression of CYP 2C8 in native porcine coronary artery endothelial cells resulted in an increase in endothelial 11,12-EET production and Erk1/2 phosphorylation compared to that detected in untreated cells or cells transfected with an antisense CYP 2C8. Endothelial cell number was unaffected by transfection with LacZ or CYP 2C8 antisense but was significantly enhanced in cells overexpressing CYP 2C8. These observations indicate that EDHF/11,12-EET is not simply a vasodilator and that its continuous release under pulsatile conditions in vivo may affect vascular cell signalling and proliferation.

The value of book distribution in a clinic-based literacy intervention program

The purpose of this study was to determine whether anticipatory guidance at well-child visits (WCV) that included early literacy development and the provision of books by the examining physician changed family literacy practices. It was conducted in an inner-city pediatric clinic that serves as the continuity practice site for pediatric and pediatric/internal medicine residents. There were 352 children (181 treatment: 171 control), aged 2 to 24 months, enrolled in this prospective, controlled study. The health care providers underwent training on literacy and on how to incorporate this information during WCV. Anticipatory guidance on safety, development, and early literacy was given to all parents. Additionally, the treatment group received an age-appropriate book at each WCV. There were 1,263 visits made (686 treatment, 577 control). Questionnaires were completed by parents on physician helpfulness and by physicians on parental receptiveness. Parental ratings on physician helpfulness were higher in the treatment group than in the control group (p<0.05). Physician's rating of parental receptiveness was also higher in the treatment group than in the control group (p<0.05). Two years after enrollment, mother-child pairs who received guidance and a book were two times more likely to report enjoyment in reading together than the controls who received guidance but no book. We conclude that anticipatory guidance that included early literacy development and distribution of books at WCV resulted in increased family literacy orientation, parental receptiveness, and perception of physician helpfulness.

Nifedipine increases cytochrome P4502C expression and endothelium-derived hyperpolarizing factor-mediated responses in coronary arteries

In addition to NO and prostacyclin, endothelial cells release a factor that elicits vasodilatation by hyperpolarizing the underlying vascular smooth muscle cells. In some vascular beds, this so-called endothelium-derived hyperpolarizing factor (EDHF) displays the characteristics of a cytochrome P450 (CYP)-derived arachidonic acid metabolite, such as an epoxyeicosatrienoic acid. Native porcine and cultured human coronary artery endothelial cells were screened for CYP epoxygenases, and CYP2B, CYP2C, and CYP2J were detected with reverse transcription-polymerase chain reaction. The CYP inducer beta-naphthoflavone and the Ca(2+) antagonist nifedipine significantly increased CYP2C mRNA but did not change the expression of CYP2J or CYP2B. To determine the relationship between CYP2C expression and EDHF production in native endothelial cells, we incubated porcine coronary arteries with nifedipine. Nifedipine enhanced endothelial CYP2C protein expression, as well as the generation of 11,12-epoxyeicosatrienoic acid. In organ bath experiments, pretreatment with nifedipine enhanced bradykinin-induced, EDHF-mediated relaxations as well as the concomitant hyperpolarization of smooth muscle cells. The specific CYP2C9 inhibitor sulfaphenazole, on the other hand, significantly attenuated EDHF-mediated hyperpolarization and relaxation. These results demonstrate that in porcine coronary arteries, the elevated expression of a CYP epoxygenase, homologous to CYP2C8/9, is associated with enhanced EDHF-mediated hyperpolarization in response to bradykinin. Therefore, we propose that an isozyme of CYP2C is the most likely candidate for the CYP-dependent EDHF synthase in porcine coronary arteries.

Analysis of flame retarded polymers and recycling materials

Recycling activities on polymeric materials are increasing and becoming more and more important in recent years. For polymers containing no flame retardants, suitable recycling strategies already exist. In order to investigate the recyclability of flame retarded polymers that contain brominated flame retardants, a number of samples were analysed as received from a recycling company. Following the identification and sorting of the samples according to type of polymers and flame retardants, material recycling was tested for the flame retarded polymers identified to occur most frequently. The reactivity of the flame retardants during the recycling procedure was studied by analysing for brominated dioxins and furans. The results demonstrate that flame retarded polymers can be recycled under certain experimental conditions.

Cytochrome P450 2C is an EDHF synthase in coronary arteries

In most arterial beds a significant endothelium-dependent dilation to various stimuli persists even after inhibition of nitric oxide synthase and cyclo-oxygenase. This dilator response is preceded by an endothelium-dependent hyperpolarization of vascular smooth muscle cells, which is sensitive to a combination of the calcium-dependent potassium-channel inhibitors charybdotoxin and apamin, and is assumed to be mediated by an unidentified endothelium-derived hyperpolarizing factor (EDHF). Here we show that the induction of cytochrome P450 (CYP) 2C8/34 in native porcine coronary artery endothelial cells by beta-naphthoflavone enhances the formation of 11,12-epoxyeicosatrienoic acid, as well as EDHF-mediated hyperpolarization and relaxation. Transfection of coronary arteries with CYP 2C8/34 antisense oligonucleotides results in decreased levels of CYP 2C and attenuates EDHF-mediated vascular responses. Thus, a CYP-epoxygenase product is an essential component of EDHF-mediated relaxation in the porcine coronary artery, and CYP 2C8/34 fulfils the criteria for the coronary EDHF synthase.

Proinflammatory mediators chronically downregulate the formation of the endothelium-derived hyperpolarizing factor in arteries via a nitric oxide/cyclic GMP-dependent mechanism

BACKGROUND

Endothelium-dependent dilator responses mediated by NO and endothelium-derived hyperpolarizing factor (EDHF) are altered in arteriosclerosis and sepsis. The possibility that proinflammatory mediators that stimulate the expression of inducible NO synthase (NOS II) affect the generation of EDHF was examined in isolated arteries.

METHODS AND RESULTS

Under combined blockade of NOS and cyclooxygenase, EDHF-mediated relaxation elicited by several agonists was significantly attenuated in rabbit carotid and porcine coronary arteries exposed to cytokines and lipopolysaccharide. The blunted relaxation was coincident with NOS II expression and was prevented by inhibition of NOS II as well as of global protein synthesis. The NO donor CAS 1609 and 8-bromo-cGMP mimicked the proinflammatory mediator effect. In contrast, long-term blockade of endothelial NO generation increased the relaxation in carotid but not in coronary arteries. Proinflammatory mediators reduced the synthesis of EDHF assessed as hyperpolarization of vascular smooth muscle cells elicited by the effluent from bradykinin-stimulated coronary arteries. Proinflammatory mediators induced NOS II expression in cultured endothelial cells and decreased the expression of cytochrome P450 enzymes, which are the most probable candidates for the synthesis of EDHF.

CONCLUSIONS

Proinflammatory mediators inhibit the formation of EDHF in isolated arteries. This impairment is coincident with NOS II expression in the arterial wall and seems to be mediated through the induced generation of NO, which downregulates the putative EDHF-forming enzyme. Thus, a decreased formation of EDHF may contribute to the endothelial dysfunction in arteriosclerosis and sepsis.

Spiral bundle nailing for subcapital humeral fractures: preliminary report of the method of Henning

This is a preliminary report of 31 patients treated with Henning's spiral bundle nails for subcapital humeral fractures. Complications included motion restriction at the elbow joint (n = 4), elbow pain caused by pin migration (n = 2), misalignment attributable to incorrect reduction (n = 4), and redislocation attributable to improper technique (n = 1), humeral head perforation (n = 3), caudal subluxation of the humeral head (n = 3), and local infections at the insertion site (n = 1). Immobilization was 3 weeks on average. By using the scoring scheme of Constant and Murley, 11 patients showed a moderate result, whereas 19 patients had an excellent outcome.

Inhibition of the production of endothelium-derived hyperpolarizing factor by cannabinoid receptor agonists

1. The endogenous cannabinoid, anandamide, has been reported to induce an 'endothelium-derived hyperpolarizing factor (EDHF)-like' relaxation in vitro. We therefore investigated the effects of cannabinoid CB1 receptor agonists; HU 210, delta9-tetrahydrocannabinol (delta9-THC) and anandamide, and a CB1 antagonist/inverse agonist, SR 141716A, on nitric oxide (NO) and EDHF-mediated relaxation in precontracted rings of porcine coronary, rabbit carotid and mesenteric arteries. 2. In rings of mesenteric artery HU 210 and delta9-THC induced endothelium- and cyclo-oxygenase-independent relaxations which were sensitive to SR 141716A. Anandamide (0.03-30 microM) induced a slowly developing, endothelium-independent relaxation which was abolished by diclofenac and was therefore mediated by cyclo-oxygenase product(s). None of the CB1 agonists tested affected the tone of precontracted rings of rabbit carotid or porcine coronary artery. 3. In endothelium-intact segments, HU 210, delta9-THC and anandamide did not affect NO-mediated responses but under conditions of continuous NO synthase/cyclo-oxygenase blockade, significantly inhibited acetylcholine and bradykinin-induced relaxations which are attributed to the production of EDHF. The effects of HU 210 and delta9-THC were not observed when experiments were performed in the presence of SR 141716A suggesting the involvement of the CB1 receptor. 4. In a patch clamp bioassay of EDHF production, HU 210 decreased the EDHF-mediated hyperpolarization of detector smooth muscle cells when applied to the donor segment but was without effect on the membrane potential of detector cells. The inhibition of EDHF production was unrelated to alterations in Ca2+ -signalling or cytochrome P450 activity. 5. These results suggest that the activation of endothelial CB1 receptors appears to be negatively coupled to the production of EDHF.

Pulsatile stretch in coronary arteries elicits release of endothelium-derived hyperpolarizing factor: a modulator of arterial compliance

To date, the release of the endothelium-derived hyperpolarizing factor (EDHF) has been demonstrated only in response to receptor-dependent Ca2+-elevating agonists. Since endothelial cells in situ are continuously subjected to rhythmic distension, we investigated the effect of rhythmic stretch on the release of EDHF from isolated porcine coronary arteries. In the combined presence of diclofenac and N(G)-nitro-L-arginine (L-NNA), sinusoidal pressure oscillations (from 40 to 50 mm Hg, 4 minutes, 1.5 Hz) led to simultaneous oscillations in the external diameter of coronary artery segments, the amplitude of which were decreased by iberiotoxin and apamin and also by endothelial denudation. In order to directly demonstrate the release of EDHF, the intraluminal solution from endothelium-intact coronary segments exposed to pulsatile stretch was applied to detector rat aortic smooth muscle cells, the membrane potential of which was continuously measured using the patch-clamp technique. The hyperpolarization of detector cells induced by the intraluminal solution was proportional to the amplitude of the pressure oscillations applied to the donor artery and was attenuated by either preincubation of donor arteries with 17-octadecynoic acid or application of either tetrabutylammonium or iberiotoxin to detector cells. In contrast to the bradykinin-induced release of EDHF, the EDHF synthesized in response to pulsatile stretch did not exhibit any tachyphylaxis. These findings demonstrate for the first time that the synthesis of EDHF in coronary arteries can be mechanically stimulated by rhythmic vessel wall distension and suggest that the continuous release of EDHF may contribute to the adjustment of an adequate vascular compliance and to the control of coronary blood flow.

Recommendations for training in performance and interpretation of stress echocardiography. Committee on Physician Training and Education of the American Society of Echocardiography

Stress echocardiography has emerged as a clinically useful procedure in the management of patients with ischemic heart disease and other conditions. However, the accuracy of this test relies on the ability of those who carry out the technical aspects of the test and depends critically on proper interpretation of the images. Appreciation of wall motion abnormalities is generally acknowledged as one of the most difficult skills to master in echocardiography. There is consensus that this is also one of the most difficult skills to teach. Appreciating stress-induced changes in wall motion, which sometimes are subtle, requires a significant commitment to initial training in this skill and its maintenance. This document provides recommendations for physician training in stress echocardiography.

Endothelium-derived hyperpolarizing factor, but not nitric oxide, is reversibly inhibited by brefeldin A

The subcellular localization of the enzymes synthesizing endothelium-derived vasodilator autacoids has been proposed to play a role in determining the ability of endothelial cells to enhance autacoid production in response to stimulation. We therefore investigated the effects of brefeldin A-induced disruption of the Golgi apparatus and Golgi-plasma membrane trafficking on the production of nitric oxide (NO), prostacyclin, and the endothelium-derived hyperpolarizing factor (EDHF) by native and cultured endothelial cells. In porcine coronary artery segments, brefeldin A (35 micromol/L, 90 minutes) did not affect relaxations to sodium nitroprusside or the K+ channel opener cromakalim but elicited a rightward shift in the concentration-response curve to bradykinin without altering the maximum vasodilator response (Rmax). Brefeldin A failed to attenuate the bradykinin-induced, NO-mediated relaxation under depolarizing conditions but inhibited the bradykinin response under conditions of combined cyclooxygenase/NO synthase blockade, suggesting that this agent selectively interferes with the production of EDHF. Indeed, incubation of porcine coronary arteries with brefeldin A, which did not affect the bradykinin-induced accumulation of either cyclic GMP or 6-keto-prostaglandin F1alpha, markedly and reversibly attenuated the EDHF-mediated hyperpolarization of detector smooth muscle cells in a patch-clamp bioassay system. The microtubule destabilizer nocodazole also affected both the EC50 and Rmax to bradykinin in porcine coronary arteries. Since EDHF is thought to be a cytochrome P450-derived metabolite of arachidonic acid and both brefeldin A and nocodazole are known to interfere with the targeting of cytochrome P450 from the Golgi apparatus to the plasma membrane, it is conceivable that brefeldin A inhibits EDHF formation by preventing the targeting of the EDHF-synthesizing enzymes to the plasma membrane.