Glycosaminoglycan-mediated lipoprotein uptake protects cancer cells from ferroptosis

Lipids are essential for tumours because of their structural, energetic, and signaling roles. While many cancer cells upregulate lipid synthesis, growing evidence suggests that tumours simultaneously intensify the uptake of circulating lipids carried by lipoproteins. Which mechanisms promote the uptake of extracellular lipids, and how this pool of lipids contributes to cancer progression, are poorly understood. Here, using functional genetic screens, we find that lipoprotein uptake confers resistance to lipid peroxidation and ferroptotic cell death. Lipoprotein supplementation robustly inhibits ferroptosis across numerous cancer types. Mechanistically, cancer cells take up lipoproteins through a pathway dependent on sulfated glycosaminoglycans (GAGs) linked to cell-surface proteoglycans. Tumour GAGs are a major determinant of the uptake of both low and high density lipoproteins. Impairment of glycosaminoglycan synthesis or acute degradation of surface GAGs decreases the uptake of lipoproteins, sensitizes cells to ferroptosis and reduces tumour growth in mice. We also find that human clear cell renal cell carcinomas, a distinctively lipid-rich tumour type, display elevated levels of lipoprotein-derived antioxidants and the GAG chondroitin sulfate than non-malignant human kidney. Altogether, our work identifies lipoprotein uptake as an essential anti-ferroptotic mechanism for cancer cells to overcome lipid oxidative stress in vivo, and reveals GAG biosynthesis as an unexpected mediator of this process.

TFCP2 is a transcriptional regulator of heparan sulfate assembly and melanoma cell growth

Heparan sulfate (HS) is a long, linear polysaccharide that is ubiquitously expressed in all animal cells and plays a key role in many cellular processes, including cell signaling and development. Dysregulation of HS assembly has been implicated in pathophysiological conditions, such as tumorigenesis and rare genetic disorders. HS biosynthesis occurs in a non-template-driven manner in the endoplasmic reticulum and Golgi through the activity of a large group of biosynthetic enzymes. While much is known about its biosynthesis, little is understood about the regulation of HS assembly across diverse tissue types and disease states. To address this gap in knowledge, we recently performed genome-wide CRISPR/Cas9 screens to identify novel regulatory factors of HS biosynthesis. From these screens, we identified the alpha globin transcription factor, TFCP2, as a top hit. To investigate the role of TFCP2 in HS assembly, we targeted TFCP2 expression in human melanoma cells using the CRISPR/Cas9 system. TFCP2 knockout cells exhibited decreased fibroblast growth factor binding to cell surface HS, alterations in HS composition, and slowed cell growth compared to wild-type cells. Additionally, RNA sequencing revealed that TFCP2 regulates the expression of multiple enzymes involved in HS assembly, including the secreted endosulfatase, SULF1. Pharmacological targeting of TFCP2 activity similarly reduced growth factor binding and increased SULF1 expression, and the knockdown of SULF1 expression in TFCP2 mutant cells restored melanoma cell growth. Overall, these studies identify TFCP2 as a novel transcriptional regulator of HS and highlight HS-protein interactions as a possible target to slow melanoma growth.

Colopathy Associated with Pentosan Polysulfate Use

Introduction

We describe a novel colopathy associated with pentosan polysulfate (PPS) use and measure the strength of the drug-disease association.

Methods

Two-part investigation. In the cohort study of individuals with a history of prior long-term PPS use, case histories were obtained and gastrointestinal disease course was followed with review of endoscopy records and histopathology specimens. Findings were summarized with descriptive statistics. In the cross-sectional study of individuals with interstitial cystitis, drug exposure and medical histories were obtained for patients seen at a single clinical center. Strength of association between PPS use and diagnoses of inflammatory bowel disease (IBD) and/or irritable bowel syndrome (IBS) was measured with multivariate logistic regression.

Results

In the cohort study of 13 participants, median PPS exposure was 2.04 kg (0.99-2.54). Eleven (84.6%) developed symptoms suggestive of IBD and/or IBS after initiation of PPS therapy. Of the 10 participants whose endoscopic and histopathologic findings we reviewed, six had abnormal-appearing colonic mucosa on endoscopy and all 10 had abnormal mucosal changes on histology. Clinical and histologic improvement was observed after PPS cessation. In the cross-sectional study of 219 subjects with interstitial cystitis, PPS use was a statistically significant predictor of both the IBD [adjusted odds ratio=3.3 (95% confidence interval, 1.2-8.8, p=0.02)] and the composite IBD+IBS [adjusted odds ratio=3.3 (95% confidence interval, 1.5-7.3, p=0.002)] outcomes.

Discussion

We describe a strong association between PPS use and a clinical diagnosis of IBD and/or IBS. Histopathologic findings suggest a novel drug-associated colopathy, with some subjects requiring colectomy for dysplasia.

Glycosaminoglycan Analysis: Purification, Structural Profiling, and GAG-Protein Interactions

Glycosaminoglycans (GAGs) are long, linear polysaccharides that are ubiquitously expressed on the cell surface and in the extracellular matrix of all animal cells. These complex carbohydrates are composed of alternating glucosamine and uronic acids that can be heterogeneously N- and O-sulfated. The arrangement and orientation of the sulfated sugar residues specify the location of distinct ligand binding sites on the cell surface, and their capacity to bind ligands impacts cell growth and development, the ability to form tissues and organs, and normal physiology. The heterogeneous nature of GAGs and their inherent structural diversity across different tissues, cell types, and disease states creates challenges to characterizing their structure and function. Here, we describe detailed methods to investigate GAG-protein interactions in vitro and evaluate the structural composition of two classes of sulfated GAGs, heparan sulfate and chondroitin/dermatan sulfate, using liquid chromatography, mass spectrometry, and radiolabeling techniques. Overall, these methods facilitate the evaluation of GAG structure and function to uncover the unique roles these molecules play in cell biology and human disease.

Spatiotemporal diversity and regulation of glycosaminoglycans in cell homeostasis and human disease

Glycosaminoglycans (GAGs) are long, linear polysaccharides that are ubiquitously expressed on the cell surface and in the extracellular matrix of all animal cells. These complex carbohydrates play important roles in many cellular processes and have been implicated in many disease states, including cancer, inflammation, and genetic disorders. GAGs are among the most complex molecules in biology with enormous information content and extensive structural and functional heterogeneity. GAG biosynthesis is a nontemplate-driven process facilitated by a large group of biosynthetic enzymes that have been extensively characterized over the past few decades. Interestingly, the expression of the enzymes and the consequent structure and function of the polysaccharide chains can vary temporally and spatially during development and under certain pathophysiological conditions, suggesting their assembly is tightly regulated in cells. Due to their many key roles in cell homeostasis and disease, there is much interest in targeting the assembly and function of GAGs as a therapeutic approach. Recent advances in genomics and GAG analytical techniques have pushed the field and generated new perspectives on the regulation of mammalian glycosylation. This review highlights the spatiotemporal diversity of GAGs and the mechanisms guiding their assembly and function in human biology and disease.

TCAD Modeling of Resistive-Switching of HfO2 Memristors: Efficient Device-Circuit Co-Design for Neuromorphic Systems

In neuromorphic computing, memristors (or “memory resistors”) have been primarily studied as key elements in artificial synapse implementations, where the memristor provides a variable weight with intrinsic long-term memory capabilities, based on its modifiable resistive-switching characteristics. Here, we demonstrate an efficient methodology for simulating resistive-switching of HfO2 memristors within Synopsys TCAD Sentaurus—a well established, versatile framework for electronic device simulation, visualization and modeling. Kinetic Monte Carlo is used to model the temporal dynamics of filament formation and rupture wherein additional band-to-trap electronic transitions are included to account for polaronic effects due to strong electron-lattice coupling in HfO2. The conductive filament is modeled as oxygen vacancies which behave as electron traps as opposed to ionized donors, consistent with recent experimental data showing p-type conductivity in HfOx films having high oxygen vacancy concentrations and ab-initio calculations showing the increased thermodynamic stability of neutral and charged oxygen vacancies under conditions of electron injection. Pulsed IV characteristics are obtained by inputting the dynamic state of the system—which consists of oxygen ions, unoccupied oxygen vacancies, and occupied oxygen vacancies at various positions—into Synopsis TCAD Sentaurus for quasi-static simulations. This allows direct visualization of filament electrostatics as well as the implementation of a nonlocal, trap-assisted-tunneling model to estimate current-voltage characteristics during switching. The model utilizes effective masses and work functions of the top and bottom electrodes as additional parameters influencing filament dynamics. Together, this approach can be used to provide valuable device- and circuit-level insight, such as forming voltage, resistance levels and success rates of programming operations, as we demonstrate.

Genome-wide screens uncover KDM2B as a modifier of protein binding to heparan sulfate

Heparan sulfate (HS) proteoglycans bind extracellular proteins that participate in cell signaling, attachment and endocytosis. These interactions depend on the arrangement of sulfated sugars in the HS chains generated by well-characterized biosynthetic enzymes; however, the regulation of these enzymes is largely unknown. We conducted genome-wide CRISPR-Cas9 screens with a small-molecule ligand that binds to HS. Screening of A375 melanoma cells uncovered additional genes and pathways impacting HS formation. The top hit was the epigenetic factor KDM2B, a histone demethylase. KDM2B inactivation suppressed multiple HS sulfotransferases and upregulated the sulfatase SULF1. These changes differentially affected the interaction of HS-binding proteins. KDM2B-deficient cells displayed decreased growth rates, which was rescued by SULF1 inactivation. In addition, KDM2B deficiency altered the expression of many extracellular matrix genes. Thus, KDM2B controls proliferation of A375 cells through the regulation of HS structure and serves as a master regulator of the extracellular matrix.

The Prolyl-tRNA Synthetase Inhibitor Halofuginone Inhibits SARS-CoV-2 Infection

We identify the prolyl-tRNA synthetase (PRS) inhibitor halofuginone ¹ , a compound in clinical trials for anti-fibrotic and anti-inflammatory applications ² , as a potent inhibitor of SARS-CoV-2 infection and replication. The interaction of SARS-CoV-2 spike protein with cell surface heparan sulfate (HS) promotes viral entry ³ . We find that halofuginone reduces HS biosynthesis, thereby reducing spike protein binding, SARS-CoV-2 pseudotyped virus, and authentic SARS-CoV-2 infection. Halofuginone also potently suppresses SARS-CoV-2 replication post-entry and is 1,000-fold more potent than Remdesivir ⁴ . Inhibition of HS biosynthesis and SARS-CoV-2 infection depends on specific inhibition of PRS, possibly due to translational suppression of proline-rich proteins. We find that pp1a and pp1ab polyproteins of SARS-CoV-2, as well as several HS proteoglycans, are proline-rich, which may make them particularly vulnerable to halofuginone's translational suppression. Halofuginone is orally bioavailable, has been evaluated in a phase I clinical trial in humans and distributes to SARS-CoV-2 target organs, including the lung, making it a near-term clinical trial candidate for the treatment of COVID-19.

Differential effects of abaloparatide and teriparatide on hip cortical volumetric BMD by DXA-based 3D modeling

In postmenopausal osteoporotic women in ACTIVE, abaloparatide reduced fracture risk and increased areal bone mineral density (BMD) more than teriparatide at the hip and wrist. DXA-based 3D modeling showed significantly greater increases in hip cortical volumetric BMD with abaloparatide versus teriparatide. This may explain differences reported in aBMD by DXA.

INTRODUCTION

In ACTIVE, abaloparatide (ABL) increased bone mineral density (BMD) shown by dual-energy X-ray absorptiometry (DXA) while reducing fracture incidence in postmenopausal osteoporotic women. Changes in DXA BMD with ABL, 80 μg, were significantly greater than with open-label teriparatide (TPTD), 20 μg, at cortical sites including total hip, femoral neck, and 1/3 distal radius. The purpose of this study was to better understand the relative effects of ABL and TPTD on cortical and cancellous compartments in the proximal femur.

METHODS

Hip DXA images from a subset of randomly selected patients in the ACTIVE trial (n = 250/arm) were retrospectively analyzed using three-dimensional modeling methods (3D-SHAPER software) to evaluate changes from baseline at months 6 and 18.

RESULTS

Similar significant increases in trabecular volumetric BMD (vBMD, + 9%) and cortical thickness (+ 1.5%) were observed with ABL and TPTD by 3D-DXA at 18 months. In contrast, only ABL significantly increased cortical vBMD versus baseline (+ 1.3%), and changes in both cortical vBMD and cortical surface BMD were significantly greater with ABL versus TPTD. In the TPTD group, changes in cortical vBMD were inversely correlated with changes in serum CTX (carboxy-terminal telopeptide of type I collagen) and PINP (procollagen type I N-terminal propeptide), suggesting that higher bone turnover may have attenuated cortical gains.

CONCLUSION

These results suggest previously reported differences in areal BMD increases between ABL and TPTD may be due to differential effects on cortical vBMD. Further studies are warranted to investigate how these differences affect therapeutic impact on hip strength in postmenopausal women with osteoporosis.

Characterizing patients initiating abaloparatide, teriparatide, or denosumab in a real-world setting: a US linked claims and EMR database analysis

We characterized patients initiating abaloparatide (ABL), teriparatide (TPTD), or denosumab (DMAB) in a real-world clinical setting from a large medical and pharmacy claims database. Differences were noted in sex, age, pathologic fractures, comorbidity index, and prior bisphosphonate use for patients initiating ABL and TPTD compared with those receiving DMAB.

INTRODUCTION

To characterize patients initiating abaloparatide (ABL), teriparatide (TPTD), or denosumab (DMAB) treatment in a real-world clinical setting.

METHODS

Patients aged ≥ 18 years initiating ABL, TPTD, or DMAB between May 1, 2017, and September 24, 2018 (without receiving the same drug in the previous 12 months), were identified using the OM1 Data Cloud, which contains medical and pharmacy claims from approximately 200 million US patients. The index date was the date of initial prescription or dispensing for ABL, TPTD, or DMAB during the study period.

RESULTS

During the study period, 2666 patients initiated ABL, 9210 TPTD, and 116,718 DMAB. Mean age (standard deviation) was 69.2 (10.6) years for the ABL cohort, 68.6 (11.3) for TPTD, and 72.1 (10.2) for DMAB (P < 0.001; ABL vs DMAB). Proportionally more patients initiating ABL were female (95.2% ABL, 86.9% TPTD, and 91.3% DMAB, P < 0.001 ABL vs TPTD or DMAB). Nearly twice as many patients initiating ABL (19.1%) and TPTD (18.8%) had a previous pathologic/fragility fracture vs DMAB (9.6%; P < 0.001 ABL vs DMAB). Fewer patients initiating ABL (36.3%) or TPTD (39.7%) had Charlson comorbidity index of ≥ 2 vs DMAB (48.4%; P < 0.001 ABL vs DMAB). Before initiating ABL, TPTD, or DMAB, 44.3%, 33.8%, and 33.9% of patients had prior osteoporosis treatment, respectively. Bisphosphonate use was more common before initiating ABL (19.2%) or TPTD (19.6%), than before initiating DMAB (16.6%; P < 0.001 ABL vs DMAB).

CONCLUSIONS

Patients initiating ABL and TPTD differed in sex, age, pathologic fractures, comorbidity index, and prior bisphosphonate use compared with those initiating DMAB.

Osteoporotic fracture trends in a population of US managed care enrollees from 2007 to 2017

This study expands on previous findings that hip fracture rates may no longer be declining. We found that age- and sex-adjusted fracture rates in the US plateaued or increased through mid-2017 in a population of commercially insured and Medicare Advantage health plan enrollees, in contrast to a decline from 2007 to 2013.

INTRODUCTION

The purpose of this study was to evaluate fracture trends in US commercial and Medicare Advantage health plan members aged ≥ 50 years between 2007 and 2017.

METHODS

Retrospective analysis of the Optum Research Database from January 1, 2007, to May 31, 2017.

RESULTS

Of 1,841,263 patients identified with an index fracture, 930,690 were case-qualifying and included in this analysis. The overall age- and sex-adjusted fracture rate decreased from 14.67/1000 person-years (py) in 2007 to 11.79/1000 py in 2013, followed by a plateau for the next 3 years and then an increase to 12.50/1000 py in mid-2017. In females aged ≥ 65 years, fracture rates declined from 27.49/1000 py in 2007 to 22.08/1000 py in 2013, then increased to 24.92/1000 py in mid-2017. Likewise, fracture rates in males aged ≥ 65 years declined from 2007 (12.00/1000 py) to 2013 (10.72/1000 py), then increased to 12.04/1000 py in mid-2017. The age- and sex-adjusted fracture rates for most fracture sites declined from 2007 to 2013 by 3.7% per year (P = 0.310).

CONCLUSIONS

Following a consistent decline in fracture rate from 2007 to 2013, trends from 2014 to 2017 indicate fracture rates are no longer declining and, for some fracture types, rates are rising.

ZNF263 is a transcriptional regulator of heparin and heparan sulfate biosynthesis

Heparin is the most widely prescribed biopharmaceutical in production globally. Its potent anticoagulant activity and safety makes it the drug of choice for preventing deep vein thrombosis and pulmonary embolism. In 2008, adulterated material was introduced into the heparin supply chain, resulting in several hundred deaths and demonstrating the need for alternate sources of heparin. Heparin is a fractionated form of heparan sulfate derived from animal sources, predominantly from connective tissue mast cells in pig mucosa. While the enzymes involved in heparin biosynthesis are identical to those for heparan sulfate, the factors regulating these enzymes are not understood. Examination of the promoter regions of all genes involved in heparin/heparan sulfate assembly uncovered a transcription factor-binding motif for ZNF263, a C2H2 zinc finger protein. CRISPR-mediated targeting and siRNA knockdown of ZNF263 in mammalian cell lines and human primary cells led to dramatically increased expression levels of HS3ST1, a key enzyme involved in imparting anticoagulant activity to heparin, and HS3ST3A1, another glucosaminyl 3-O-sulfotransferase expressed in cells. Enhanced 3-O-sulfation increased binding to antithrombin, which enhanced Factor Xa inhibition, and binding of neuropilin-1. Analysis of transcriptomics data showed distinctively low expression of ZNF263 in mast cells compared with other (non-heparin-producing) immune cells. These findings demonstrate a novel regulatory factor in heparan sulfate modification that could further advance the possibility of bioengineering anticoagulant heparin in cultured cells.

Author Correction: Dynamical nonlinear memory capacitance in biomimetic membranes

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Assembly and Characterization of Biomolecular Memristors Consisting of Ion Channel-doped Lipid Membranes

The ability to recreate synaptic functionalities in synthetic circuit elements is essential for neuromorphic computing systems that seek to emulate the cognitive powers of the brain with comparable efficiency and density. To date, silicon-based three-terminal transistors and two-terminal memristors have been widely used in neuromorphic circuits, in large part due to their ability to co-locate information processing and memory. Yet these devices cannot achieve the interconnectivity and complexity of the brain because they are power-hungry, fail to mimic key synaptic functionalities, and suffer from high noise and high switching voltages. To overcome these limitations, we have developed and characterized a biomolecular memristor that mimics the composition, structure, and switching characteristics of biological synapses. Here, we describe the process of assembling and characterizing biomolecular memristors consisting of a 5 nm-thick lipid bilayer formed between lipid-functionalized water droplets in oil and doped with voltage-activated alamethicin peptides. While similar assembly protocols have been used to investigate biophysical properties of droplet-supported lipid membranes and membrane-bound ion channels, this article focuses on key modifications of the droplet interface bilayer method essential for achieving consistent memristor performance. Specifically, we describe the liposome preparation process and the incorporation of alamethicin peptides in lipid bilayer membranes, and the appropriate concentrations of each constituent as well as their impact on the overall response of the memristors. We also detail the characterization process of biomolecular memristors, including measurement and analysis of memristive current-voltage relationships obtained via cyclic voltammetry, as well as short-term plasticity and learning in response to step-wise voltage pulse trains.

Memristive Ion Channel-Doped Biomembranes as Synaptic Mimics

Solid-state neuromorphic systems based on transistors or memristors have yet to achieve the interconnectivity, performance, and energy efficiency of the brain due to excessive noise, undesirable material properties, and nonbiological switching mechanisms. Here we demonstrate that an alamethicin-doped, synthetic biomembrane exhibits memristive behavior, emulates key synaptic functions including paired-pulse facilitation and depression, and enables learning and computing. Unlike state-of-the-art devices, our two-terminal, biomolecular memristor features similar structure (biomembrane), switching mechanism (ion channels), and ionic transport modality as biological synapses while operating at considerably lower power. The reversible and volatile voltage-driven insertion of alamethicin peptides into an insulating lipid bilayer creates conductive pathways that exhibit pinched current-voltage hysteresis at potentials above their insertion threshold. Moreover, the synapse-like dynamic properties of the biomolecular memristor allow for simplified learning circuit implementations. Low-power memristive devices based on stimuli-responsive biomolecules represent a major advance toward implementation of full synaptic functionality in neuromorphic hardware.

Surfen and oxalyl surfen decrease tau hyperphosphorylation and mitigate neuron deficits in vivo in a zebrafish model of tauopathy

Background

Tauopathies comprise a family of neurodegenerative disorders including Alzheimer’s disease for which there is an urgent and unmet need for disease-modifying treatments. Tauopathies are characterized by pathological tau hyperphosphorylation, which has been shown to correlate tightly with disease progression and memory loss in patients suffering from Alzheimer’s disease. We recently demonstrated an essential requirement for 3-O-sulfated heparan sulfate in pathological tau hyperphosphorylation in zebrafish, a prominent model organism for human drug discovery. Here, we investigated whether in vivo treatment with surfen or its derivatives oxalyl surfen and hemisurfen, small molecules with heparan sulfate antagonist properties, could mitigate tau hyperphosphorylation and neuronal deficits in a zebrafish model of tauopathies.

Results

In vivo treatment of Tg[HuC::hTau^P301L; DsRed] embryos for 2 days with surfen or oxalyl surfen significantly reduced the accumulation of the pThr181 tau phospho-epitope measured by ELISA by 30% and 51%, respectively. Western blot analysis also showed a significant decrease of pThr181 and pSer396/pSer404 in embryos treated with surfen or oxalyl surfen. Immunohistochemical analysis further confirmed that treatment with surfen or oxalyl surfen significantly decreased the AT8 tau epitope in spinal motoneurons. In addition, in vivo treatment of Tg[HuC::hTau^P301L; DsRed] embryos with surfen or oxalyl surfen significantly rescued spinal motoneuron axon-branching defects and, as a likely consequence, the impaired stereotypical touch-evoked escape response. Importantly, treatment with hemisurfen, a surfen derivative devoid of heparan sulfate antagonist activity, does not affect tau hyperphosphorylation, nor neuronal or behavioural deficits in Tg[HuC::hTau^P301L; DsRed] embryos.

Conclusion

Our findings demonstrate for the first time that surfen, a well-tolerated molecule in clinical settings, and its derivative, oxalyl surfen, could mitigate or delay neuronal defects in tauopathies, including Alzheimer’s disease.

Electronic supplementary material

The online version of this article (10.1186/s40035-018-0111-2) contains supplementary material, which is available to authorized users.

Surfen and oxalyl surfen decrease tau hyperphosphorylation and mitigate neuron deficits in vivo in a zebrafish model of tauopathy

BACKGROUND

Tauopathies comprise a family of neurodegenerative disorders including Alzheimer's disease for which there is an urgent and unmet need for disease-modifying treatments. Tauopathies are characterized by pathological tau hyperphosphorylation, which has been shown to correlate tightly with disease progression and memory loss in patients suffering from Alzheimer's disease. We recently demonstrated an essential requirement for 3-O-sulfated heparan sulfate in pathological tau hyperphosphorylation in zebrafish, a prominent model organism for human drug discovery. Here, we investigated whether in vivo treatment with surfen or its derivatives oxalyl surfen and hemisurfen, small molecules with heparan sulfate antagonist properties, could mitigate tau hyperphosphorylation and neuronal deficits in a zebrafish model of tauopathies.

RESULTS

In vivo treatment of Tg[HuC::hTau^P301L; DsRed] embryos for 2 days with surfen or oxalyl surfen significantly reduced the accumulation of the pThr181 tau phospho-epitope measured by ELISA by 30% and 51%, respectively. Western blot analysis also showed a significant decrease of pThr181 and pSer396/pSer404 in embryos treated with surfen or oxalyl surfen. Immunohistochemical analysis further confirmed that treatment with surfen or oxalyl surfen significantly decreased the AT8 tau epitope in spinal motoneurons. In addition, in vivo treatment of Tg[HuC::hTau^P301L; DsRed] embryos with surfen or oxalyl surfen significantly rescued spinal motoneuron axon-branching defects and, as a likely consequence, the impaired stereotypical touch-evoked escape response. Importantly, treatment with hemisurfen, a surfen derivative devoid of heparan sulfate antagonist activity, does not affect tau hyperphosphorylation, nor neuronal or behavioural deficits in Tg[HuC::hTau^P301L; DsRed] embryos.

CONCLUSION

Our findings demonstrate for the first time that surfen, a well-tolerated molecule in clinical settings, and its derivative, oxalyl surfen, could mitigate or delay neuronal defects in tauopathies, including Alzheimer's disease.

Targeting heparin and heparan sulfate protein interactions

Heparin and heparan sulfate glycosaminoglycans are long, linear polysaccharides that are made up of alternating dissacharide sequences of sulfated uronic acid and amino sugars. Unlike heparin, which is only found in mast cells, heparan sulfate is ubiquitously expressed on the cell surface and in the extracellular matrix of all animal cells. These negatively-charged glycans play essential roles in important cellular functions such as cell growth, adhesion, angiogenesis, and blood coagulation. These biomolecules are also involved in pathophysiological conditions such as pathogen infection and human disease. This review discusses past and current methods for targeting these complex biomolecules as a novel therapeutic strategy to treating disorders such as cancer, neurodegenerative diseases, and infection.

Abstract 5945: CRISPR-Cas9 dissection of heparan sulfate

Heparan sulfate proteoglycans (HSPGs) are expressed on virtually all animal cells and play important roles in tumor growth and metastasis. Each HSPG consists of a core protein with one or more covalently attached linear heparan sulfate (HS) chains composed of alternating glucosamine and uronic acids that are heterogeneously N- and O-sulfated. These complex cell surface carbohydrates regulate important biological processes including cell proliferation and development through their interaction with a large number of matrix proteins and growth factors. The arrangement and orientation of the sulfated sugar residues of HS specify the location of distinct ligand binding sites on the cell surface, and these modifications can vary temporally during development and spatially across tissues. Previous studies have shown that HSPGs can modulate tumor growth kinetics and are abundantly expressed on the cell surface of many types of cancer. Additionally, genetically reducing the sulfation of HS has been shown to selectively inhibit tumor angiogenesis and lymph node metastasis. While most of the enzymes involved in HS biosynthesis have been studied extensively, much less information exists regarding the specific mechanisms that give rise to the variable composition and binding properties of HS. The overall goal of this project is to uncover and characterize novel genes whose expression influences HS-mediated regulatory networks in tumor growth and metastasis. A genome-wide CRISPR/Cas9-mediated screen was developed to uncover and characterize novel genes other than those encoding known HS biosynthetic enzymes. A lentiviral single guide RNA (sgRNA) library was utilized to knock down gene expression across the entire genome in a human malignant melanoma cell line. Subsequently, a high-throughput screening assay was adapted to identify lentiviral-encoded sgRNAs that induce resistance to cytotoxins whose action depends on HSPGs. Parallel screens using alternative HS-dependent toxins or plant lectins that cause cytotoxicity dependent on other types of glycosylation were performed in order to sort genes that selectively affect HS biosynthesis. From the toxin screens, we identified previously studied genes essential for HS formation and factors involved in the intoxication of cells by diphtheria toxin, an HS-dependent exotoxin. Furthermore, we uncovered potential candidate genes whose function is unknown relative to HS biosynthesis. Top hits from the screens were characterized and categorized based on their predicted gene functions and are currently being individually validated and examined for their potential involvement in the regulation of HS biosynthesis. Overall, these studies will provide a better understanding of the genetic regulatory factors involved in HS biogenesis. Additionally, the factors we identify could reveal novel targets for anti-cancer therapies, as well as lead us to methods to manipulate HS and its activities in other cellular processes that go awry in human diseases.

Citation Format: Ryan J. Weiss, Philipp N. Spahn, Nathan E. Lewis, Jeffrey D. Esko. CRISPR-Cas9 dissection of heparan sulfate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5945. doi:10.1158/1538-7445.AM2017-5945

Small molecule antagonists of cell-surface heparan sulfate and heparin-protein interactions

Surfen, bis-2-methyl-4-amino-quinolyl-6-carbamide, was previously reported as a small molecule antagonist of heparan sulfate (HS), a key cell-surface glycosaminoglycan found on all mammalian cells. To generate structure-activity relationships, a series of rationally designed surfen analogs was synthesized, where its dimeric structure, exocyclic amines, and urea linker region were modified to probe the role of each moiety in recognizing HS. An in vitro assay monitoring inhibition of fibroblast growth factor 2 binding to wild-type CHO cells was utilized to quantify interactions with cell surface HS. The dimeric molecular structure of surfen and its aminoquinoline ring systems was essential for its interaction with HS, and certain dimeric analogs displayed higher inhibitory potency than surfen and were also shown to block downstream FGF signaling in mouse embryonic fibroblast cells. These molecules were also able to antagonize other HS-protein interactions including the binding of soluble RAGE to HS. Importantly, selected molecules were shown to neutralize heparin and other heparinoids, including the synthetic pentasaccharide fondaparinux, in a factor Xa chromogenic assay and in vivo in mice. These results suggest that small molecule antagonists of heparan sulfate and heparin can be of therapeutic potential for the treatment of disorders involving glycosaminoglycan-protein interactions.

Rearrangement of 3-membered 1,1,2-trifluorobromonium and iodonium ions and comparison of trifluorochloronium to fluorocarbenium ions

Reactions of chlorine (Cl(2)) with 4-halo-1,1,2-trifluorobut-1-enes (1, 2, or 3) give open-ion intermediates A and E that are in equilibrium. The open-chloronium ions (E) rearrange to a five-membered-ring halonium ion during ionic chlorination of 3 when the number-4 halo-substituent is iodine. Three-membered-ring bromonium and iodonium ions from alkenes 1, 2, or 3 are rather symmetrical and similar in structure. Quantum chemical calculations show that five-membered-ring halonium ion intermediates are 11 to 27 kcal/mol more stable than the three-membered-ring halonium ions or the open-ions A and E. The five-membered-ring intermediates lead to rearranged products. Rearranged products increase as the number-4 halogen (Z) becomes more nucleophilic (Z: Cl < Br < I). Open chloronium ions from ionic chlorination of terminal fluorovinyl alkenes are compared to the open ions generated by protons to similar alkenes.

Decrease of RA-related orthopaedic surgery of the upper limbs between 1998 and 2004: data from 54,579 Swedish RA inpatients

OBJECTIVES

To describe the overall use and temporal trends in orthopaedic upper limb surgery associated with RA on a nation wide basis in Sweden between 1998 and 2004.

METHODS

Data for all inpatient visits during 1998-2004 for patients older than 18 yrs with RA-related diagnoses were extracted from the Swedish National Hospital Discharge Registry (SNHDR). The SNHDR prospectively collects data on all hospital admissions in Sweden according to the International Classification of Diseases (ICD). Data were analysed with respect to orthopaedic surgery of the hand, elbow and shoulder.

RESULTS

During the study period, 54,579 individual RA patients were admitted to a Swedish hospital and 9% of these underwent RA-related surgery of the upper limbs. The RA patient cohort underwent a total of 8251 RA-related upper limb surgical procedures. The hand (77%) was most frequently operated on, followed by the shoulder (13%) and the elbow (10%). There was a statistically significant decrease of 31% for all admissions associated with RA-related upper limb surgery during 1998-2004 (P = 0.001). Some 10% of all RA-related upper limb surgery was due to total joint arthroplasties (TJAs), mostly for the elbow (59%). During 1998-2004, all TJAs, elbow-TJAs and shoulder-TJAs had a stable occurrence. In contrast, the overall numbers of hand-TJAs significantly increased (P = 0.009).

CONCLUSIONS

Rates of RA-related upper limb surgery decreased and TJAs had a stable occurrence in Sweden during 1998-2004. The findings of this study may reflect trends in disease management and health outcomes of RA patients in Sweden.

Ankle/hindfoot arthrodesis in rheumatoid arthritis improves kinematics and kinetics of the knee and hip: a prospective gait analysis study

OBJECTIVES

To evaluate the effects of ankle/hindfoot arthrodesis in rheumatoid arthritis (RA) patients on gait pattern of the knee and hip.

METHODS

In this prospective follow-up study, 14 RA patients scheduled for ankle/hindfoot arthrodesis (talo-calcaneal, talo-navicular, calcaneo-cuboid and/or talo-crural joints) and 14 age- and sex-matched healthy controls were included. Three-dimensional gait analyses of joint angles, moments and work were performed at the index operation and after 13 months of follow-up. Each patient underwent clinical assessments of pain while walking, overall evaluation of disease activity, Health Related Quality of Life Questionnaire (EQ-5D), activity limitations, maximum walking distance, difficulty with walking surface and gait abnormality. For comparisons of pre- vs post-operative conditions, Wilcoxon's matched pairs test and Friedman ANOVA by rank test were used.

RESULTS

At follow-up after ankle/hindfoot fusion surgery, RA patients demonstrated a statistically significant improvement in mean range of joint motions, moments and work in the overlying joints such as the knee and hip. Moreover, there was significantly less pain, disease activity, activity limitation, difficulty with walking surface and gait abnormality. EQ-5D and maximum walking distance were also significantly improved at follow-up.

CONCLUSIONS

Our results demonstrate that ankle/hindfoot arthrodesis in RA is an effective intervention to reduce pain and to improve Health Related Quality of Life and functional ability. Moreover, the overlying leg joints experience an improvement in joint motion, muscle-generated joint moments and work during walking. Three-dimensional gait analysis may assist future investigations of the effects of orthopaedic surgery on functional mobility in RA to prevent irreversible disablement.

Orthopaedic surgery of the lower limbs in 49,802 rheumatoid arthritis patients: results from the Swedish National Inpatient Registry during 1987 to 2001

OBJECTIVES

To analyse changes in the rates of hospital admission and use of orthopaedic surgery to the lower limbs in Swedish patients with rheumatoid arthritis between 1987 and 2001.

METHODS

Data for all rheumatoid patients admitted to hospital between 1987 and 2001 were abstracted from the Swedish National Hospital Discharge Register (SNHDR). The data in the register are collected prospectively, recording all inpatient admissions throughout Sweden. The SNHDR uses the codes for diagnoses at discharge and surgical procedures according to the Swedish version of the International Classification of Diseases (ICD).

RESULTS

In all, 49,802 individual patients with rheumatoid arthritis were identified, accounting for 159,888 inpatient visits. Hospital admissions for rheumatoid arthritis decreased by 42% (p<0.001) during the period 1987 to 2001. Twelve per cent of all admissions were for a rheumatoid arthritis related surgical procedure to the lower limbs; those admissions decreased markedly (by 16%) between 1987 and 1996, and by 12% between 1997 and 2001, as did the overall number of rheumatoid arthritis related surgical procedures to the lower limbs during both time periods. Between 1997 and 2001, 47% of all rheumatoid arthritis related surgical procedures were total joint arthroplasties. There was an overall trend towards reduced length of hospital stay after orthopaedic surgery to the lower limbs during the study period.

CONCLUSIONS

Rates of hospital admission and rheumatoid arthritis related surgical procedures to the lower limbs in Swedish patients with rheumatoid arthritis decreased between 1987 and 2001. This may reflect trends in disease severity, management, and health outcomes of this disease in Sweden.

Morphological Characterization of Receptor Activator of NFkappaB Ligand (RANKL) and IL-1beta Expression in Rodent Collagen-Induced Arthritis

Bone loss represents a major unsolved problem in rheumatoid arthritis (RA). The receptor activator of nuclear factor-kappaB ligand (RANKL) is essential for the development and activation of osteoclasts, which are key mediators of bone erosions. This study was performed to determine temporal and spatial expression of RANKL compared with the potentially destructive cytokine interleukin-1beta (IL-1beta), related to progression of synovitis and joint destruction in collagen-induced arthritis (CIA), a model of RA. CIA was induced in dark agouti (DA) rats, and tissue specimens were obtained for immunohistochemical analyses at various time points before and after disease onset. Arthritis was monitored visually, and joint pathology was examined histologically. No disease-preceding expression of RANKL was detected. However, a marked increase of both RANKL- and IL-1beta-expressing cells correlated with the progression of synovial inflammation and clinical disease severity. Abundant and concomitant expression of these cytokines was detected at sites of bone erosion, where a colocalization by osteoclast-like multinuclear tartrate-resistant acid phosphatase (TRAP)+ cells was noted. In contrast to the paucity of RANKL expression in cartilage, an abundant expression of IL-1beta was demonstrated, particularly in superficial cartilage layers. These data support the hypothesis that RANKL and IL-1beta are central contributors to joint destruction in CIA.

Clinical and radiological disease-course in a Swedish DMARD-treated early RA-inception cohort: an observational study

OBJECTIVES

Disease-modifying anti-rheumatic drugs (DMARDs) decrease clinical signs and symptoms in rheumatoid arthritis (RA). However, radiographic changes sometimes continue to accrue despite effective suppression of clinical symptoms by therapy. The objective of this study was to identify whether successful clinical disease-control in a Swedish early RA-inception cohort of patients led to an attenuation of radiological progression.

PATIENTS AND METHODS

We analysed clinical data and radiographs of 95 patients who were on a stable treatment regimen [methotrexate (MTX), sulfasalazine (SSZ), oral gold (AUR)] or who had changed between different DMARDs during the 2-year observation period [multiple therapy failures (mTF)]. Radiographs were quantified using the modified Larsen score and 'X-Ray RheumaCoach' software.

RESULTS

Clinical measures improved markedly (p <0.001) from baseline to year 2 under AUR, MTX, and SSZ therapy but not in the mTF group. Similar levels of disease control were seen for each DMARD. During this period, patients treated with AUR had a deltaLarsen score (+ 14.5+/-1.3) similar to mTF patients (+ 15.8+/-1.1) but greater than patients on MTX (+8.6+/-0.8) or SSZ (+9.1+/-0.8).

CONCLUSIONS

This study confirms that radiological progression occurs despite a clinically acceptable disease control, but also shows that, given the same degree of clinical disease control, radiological progression can be different for different DMARDs.

Radiological progression of joint damage in a longitudinal cohort of early DMARD-treated rheumatoid arthritis patients followed for 10 years

OBJECTIVE

The efficacy of DMARD therapy in rheumatoid arthritis (RA) can be judged by radiological analysis. This study aimed to determine the time-dependent progression of joint damage, acute-phase response, and rates of radiologic progression in early DMARD-treated RA patients over 10 years.

PATIENTS AND METHODS

We evaluated outpatient records, and radiographs of hands and feet of 54 early RA patients on DMARDs for 10 years. Radiographs were quantified by the Larsen method using recently developed quantification software.

RESULTS

Radiological damage attenuated, with disease progression from baseline to Year 10 [correlation coefficient (r)=0.95, probability (p)<0.001]. Radiographic scores progressed more rapidly during the first 5 years than thereafter. Cumulative erythrocyte sedimentation rate (ESR) was strongly correlated with radiological progression (p<0.001, r=0.88).

CONCLUSION

Our findings reveal a higher amount of radiographic RA progression during the first years of DMARD treatment. Thus, our data provide strong evidence for the importance of both early DMARD therapy and continuous radiographic assessments in RA.

Estimated prediagnosis radiological progression: an important tool for studying the effects of early disease modifying antirheumatic drug treatment in rheumatoid arthritis

OBJECTIVE

To determine if intrapatient comparisons between prediagnosis and subsequent radiological progression could be used to assess effects of DMARDs in an RA inception cohort.

PATIENTS AND METHODS

149 non-randomised patients with newly diagnosed RA in four groups were analysed: patients treated with (a) methotrexate (n = 56); (b) sulfasalazine (n = 55); (c) auranofin (n = 19); and (d) controls who were poor treatment responders (n = 19). Radiographs were quantified using the Larsen erosion score. The prediagnosis radiological progression from the onset of RA symptoms to diagnosis was calculated and compared with the observed progression rate during the first year after diagnosis while receiving DMARD treatment.

RESULTS

Mean (SD) disease duration from onset of symptoms until diagnosis was 6.7 (4.0) months. Mean (SD) baseline Larsen score was 13.2 (9.3), giving a mean (SD) estimated prediagnosis progression rate of 23.6 (12.4) Larsen score units/year. Control and auranofin groups showed radiological progression after diagnosis similar to the progression predicted by prediagnosis progression rates. Patients receiving methotrexate or sulfasalazine showed a marked reduction (71% and 73%, respectively; p<0.001) in radiographic progression compared with prediagnosis progression.

CONCLUSIONS

Prediagnosis rates of radiological progression can be used quantitatively to obtain information on the potential efficacy of DMARDs, and indicate that methotrexate and sulfasalazine, but not auranofin, significantly retard radiographic damage in the first year after diagnosis.

[Improving local control in patients with aggressive fibromatosis by combined surgery and radiotherapy]

INTRODUCTION

The purpose of this retrospective analysis is to evaluate whether the combination of surgery and radiation therapy in patients with aggressive fibromatosis influences the therapeutic outcome.

METHOD

Clinical, radiological and pathological results of 23 consecutive cases with histologically proven aggressive fibromatosis were retrospectively analyzed. The median follow-up was 59 months.

RESULTS

Twelve patients received surgery alone for their first treatment, 10 patients had a combination of surgery and radiotherapy and 1 patient had radiochemotherapy. Of 23 patients 14 (63%) had one or more local recurrences and 9 (39%) were recurrence-free. The patients received a total of 50 treatments: 29/50 (58%) treatments were followed by a local recurrence and 21/50 (42%) were without relapse. Twenty-nine treatments with local recurrence consisted of 25/29 (86%) surgical treatments, 3/29 (10%) combinations of surgery and radiation therapy, and 1/29 (3%) radiochemotherapy. Of the patients who had only surgery for their first treatment, after one year 8 of 12 (66%) and after 5 years all patients had a local recurrence. In the group with surgery and radiotherapy, there was no recurrence after 1 year and 1 recurrence after 5 years (p = 0.0001).

CONCLUSION

We recommend a complete tumor resection, without mutilating the patient. Radiation therapy in combination with surgery in contrast to surgery alone is an efficient treatment option for reducing local recurrence.

Influence of sodium intake on the reliability of active renin as a measure of the renin-angiotensin system in essential hypertension

Plasma renin activity (PRA), active renin (AR), prorenin, and angiotensinogen were assessed in 486 hypertensive and 175 normotensive subjects with a sodium intake of 10 or 200 mEq/d during supine and upright posture and after infusion of angiotensin II. PRA and AR levels were compared in hypertensive subjects in each condition. With low sodium intake, particularly while upright, there was a significant correlation between PRA and AR. In upright subjects with low sodium intake who had a PRA of 2.4 ng/mL per hour or less (1.85 nmol.L-1.h-1 or less), the correlation was also strong. With high sodium intake, the correlation was weaker. With intermediate sodium excretion, the correlation was intermediate. Prorenin was less predictive of PRA than was AR, and angiotensinogen had a marginal role. Using PRA during sodium restriction while upright as the standard for determining renin status, the precision of AR for predicting renin status was excellent. AR may be used for surrogate assessment of the renin-angiotensin system activity when the system is activated.

Fluvastatin titrate-to-goal clinical practice study

The efficacy and safety of fluvastatin in patients with moderate hypercholesterolemia was evaluated in this open-label, multicenter trial. Patients whose cholesterol did not meet National Cholesterol Education Program guidelines after an 8-week dietary stabilization period underwent a 12-week treatment period. The study population was 1776 patients ranging in age from 18 to 75 years with an average low-density lipoprotein cholesterol level for two visits of 160 to 200 mg/dL. For all patients, the mean serum level of low-density lipoprotein cholesterol showed a decrease of 21% between baseline and week 12 (177.8 +/- 19.0 to 141.0 +/- 22.7 mg/dL). Total cholesterol decreased 14% (263.3 +/- 24.3 to 224.2 +/- 12.9 mg/dL). Triglycerides decreased 14% (183.7 +/- 82.3 to 158.0 +/- 70.1 mg/dL). High-density lipoprotein cholesterol levels increased only slightly (49.7 +/- 12.1 to 51.8 +/- 12.9 mg/dL). Therapy with fluvastatin resulted in few adverse effects. No patient terminated the study prematurely because of laboratory abnormalities, although laboratory values of concern occurred in 0.3% of patients regarding serum glutamic oxaloacetic transaminase and in 0.07% regarding creatine phosphokinase. Fluvastatin is confirmed as effective and safe for the treatment of moderate hypercholesterolemia in the general-practice patient.

Long-term efficacy, tolerability, and safety of the combination of enalapril and felodipine ER in the treatment of hypertension. Enalapril-Felodipine ER Factorial Study Group

A recent 8-week, double-masked, placebo-controlled, 3 x 4 factorial-design study demonstrated that enalapril-felodipine extended-release (ER) combinations had statistically significant additive effects for reducing both sitting systolic blood pressure (SiSBP) and sitting diastolic blood pressure (SiDBP) and were generally well tolerated in hypertensive patients with SiDBPs ranging from 95 to 115 mm Hg. The present open-label study was undertaken to assess the long-term efficacy, tolerability, and safety of such combinations. Patients from the factorial study were eligible for the 1-year, open-label extension. Initially, all patients received enalapril 5 mg-felodipine ER 2.5 mg once daily; if SiDBP was not controlled (< 90 mm Hg) after 4 weeks of treatment, the dose was titrated upward at 2- to 4-week intervals to a maximum of enalapril 10 mg-felodipine ER 10 mg. Hydrochlorothiazide (HCTZ) 12.5 mg was added to the regimen of patients whose hypertension was not controlled at the highest enalapril-felodipine ER dose. A total of 507 patients were enrolled, of whom 502 were assessable. At their last study visit, 391 (78%) of the assessable patients were receiving only an enalapril-felodipine ER combination. The enalapril-felodipine ER combinations resulted in mean trough SiDBPs of 85 to 89 mm Hg (decreases of 13 to 16 mm Hg from baseline) and SiSBPs of 137 to 140 mm Hg (decreases of 13 to 21 mm Hg). Overall, 407 (81%) of the 502 assessable patients achieved an SiDBP < 90 mm Hg or a reduction from baseline > or = 10 mm Hg (responders); such a response was recorded in 331 patients (66%) taking a combination of enalapril-felodipine ER alone and 76 patients (15%) taking the combination with the addition of HCTZ 12.5 mg. Blood pressure reductions were maintained throughout the treatment period. Drug-related adverse events were relatively infrequent, often transient, usually mild, and apparently not dose related. The most frequently reported drug-related adverse events were edema/swelling, asthenia/fatigue, dizziness, cough, and headache. These results suggest that combination therapy with enalapril-felodipine ER is effective for long-term blood pressure reduction, has an excellent safety profile, and is generally well tolerated. Addition of low-dose HCTZ to the enalapril-felodipine ER combination appears to provide further blood pressure control without increasing drug-related adverse events.

Intracranial aneurysm and hemorrhagic stroke in glucocorticoid-remediable aldosteronism

There are anecdotal reports of early cerebrovascular complications occurring in patients with glucocorticoid-remediable aldosteronism (GRA). The issue has never been systematically evaluated. In this study, we retrospectively reviewed the International Registry for GRA to see if there was an association between cerebrovascular complications and GRA. We searched the records of 376 patients from 27 genetically proven GRA pedigrees for premature death or cerebrovascular complications. Each case was subsequently verified through the referring physician, or autopsy reports. The number of complications occurring in patients with proven GRA were compared to GRA negative subjects from the same pedigrees. There were 18 cerebrovascular events in 15 patients with proven GRA (n=167) and none in the GRA negative group (n=194; P<.001). There were an additional 15 events in 15 subjects that were suspected of having GRA based on clinical history. Seventy percent of events were hemorrhagic strokes; the overall case fatality rate was 61%. The mean (+/- SD) age at the time of the initial event was 31.7+/-11.3 years. In total, 48% of all GRA pedigrees and 18% of all GRA patients had cerebrovascular complications, which is similar to the frequency of aneurysm in adult polycystic kidney disease. GRA is associated with high morbidity and mortality from early onset of hemorrhagic stroke and ruptured intracranial aneurysms. Screening for intracranial aneurysm with magnetic resonance angiography is advised for patients with genetically proven GRA.

Combined enalapril and felodipine extended release (ER) for systemic hypertension. Enalapril-Felodipine ER Factorial Study Group

This multicenter, placebo-controlled, double-blind trial of factorial design evaluated the safety and efficacy of combination treatment with the angiotensin-converting enzyme inhibitor, enalapril, and the vascular selective calcium antagonist felodipine extended release (ER) in patients with essential hypertension. After a 4-week, single-blind placebo baseline period, 707 patients with sitting diastolic blood pressures (BPs) in the range of 95 to 115 mm Hg received placebo, enalapril (5 or 20 mg), felodipine ER (2.5, 5, or 10 mg), or their combinations for an 8-week double-blind treatment period. All doses of enalapril and felodipine ER had a statistically significant (p < 0.05) additive effect in reducing both systolic and diastolic BP. The trough to peak ratios for the combinations ranged from 0.63 (enalapril 5 mg-felodipine ER 2.5 mg) to 0.79 (enalapril 20 mg-felodipine ER 10 mg) and were consistent with effective BP control with 1 dose/day. Patients aged > or = 65 years demonstrated a greater reduction in diastolic BP. Combinations of enalapril-felodipine ER were associated with less drug-induced peripheral edema (4.1%) compared to felodipine ER monotherapy (10.8%). There were no serious drug-related adverse effects observed during the study. In this trial, the combination of enalapril and felodipine ER effectively lowered BP and was generally well tolerated with an excellent safety profile when used in the treatment of hypertension.

Hematologic and erythropoietin responses to iron dextran in the hemodialysis environment

OBJECTIVE

To investigate the hematologic and economic advantages of using iron dextran as the sole supplemental agent to safely increase and maintain hematocrit levels and iron availability while optimizing erythropoietin dosing in patients on chronic hemodialysis.

DESIGN

Iron dextran 100 mg (2 ml) was administered i.v. slow push, undiluted three times per week, sometime during the last 30 minutes of each hemodialysis treatment, until a total required ml (determined by using the package insert's formula) was attained. Maintenance doses of either 25 or 50 mg per week (dependent upon body weight) were administered ongoing to compensate for dialytic and gastrointestinal blood losses. The analysis duration was 12 months.

SAMPLE/SETTING

A prospective analysis was performed on 13 clinically stable hemodialysis outpatients in a rural community hospital-based dialysis facility (mean age 56.4 years ranging from 24-76; sample included 9 males, 4 females).

METHODS

The means and medians were calculated for each variable: hematocrit, ferritin, transferrin saturation, and erythropoietin dose. A one-tailed paired student t test was performed on doses of erythropoietin at -1 and 6 months, -1 and 9 months, and -1 and 12 months. Cost per patient of iron dextran loading dose and maintenance, as well as cost savings from actual erythropoietin dose reductions, were calculated at 3, 9, and 12 months. Cost savings reflected the cost of iron dextran.

RESULTS

After 6 months on the protocol, erythropoietin doses decreased an average of 3100 units per patient with an 8% increase in hematocrit and 66% and 78% increase in transferrin saturation and ferritin, respectively. Based on averages in actual reduced erythropoietin dosing, a savings of +5,070 per patient per year was realized.

CONCLUSIONS

This analysis found the use of iron dextran in the hemodialysis setting to be an effective and economic means to maintain hematocrit values and iron availability while optimizing erythropoietin dosing.

Addition of zatebradine, a direct sinus node inhibitor, provides no greater exercise tolerance benefit in patients with angina taking extended-release nifedipine: results of a multicenter, randomized, double-blind, placebo-controlled, parallel-group study. The Zatebradine Study Group

OBJECTIVES

We examined the antianginal and anti-ischemic effects of oral zatebradine, a direct sinus node inhibitor that has no blood pressure-lowering or negative inotropic effects in patients with chronic stable angina pectoris taking extended-release nifedipine.

BACKGROUND

Heart rate reduction is considered an important pharmacologic mechanism for providing anginal pain relief and anti-ischemic action in patients with chronic stable angina, suggesting a benefit for sinus node-inhibiting drugs.

METHODS

In a single-blind placebo run-in, randomized double-blind, placebo-controlled, multicenter study, patients already receiving extended-release nifedipine (30 to 90 mg once a day) were randomized to receive zatebradine (5 mg twice a day [n = 64]) or placebo (n = 60). All subjects had reproducible treadmill exercise-induced angina at baseline, and after randomization they performed a serial exercise test 3 h after each dose for 4 weeks.

RESULTS

Zatebradine reduced rest heart rate both at 4 weeks ([mean +/- SEM] 12.9 +/- 1.23 vs. 2.3 +/- 1.6 [placebo] beats/min, p < 0.0001) and at the end of comparable stages of Bruce exercise (16.7 +/- 1.2 vs. 3.4 +/- 1.2 [placebo] beats/min, p < 0.0001). Despite the significant effects on heart rate at rest and exercise, there were no additional benefits of zatebradine from placebo baseline in measurements of total exercise duration, time to 1-mm ST segment depression or time to onset of angina. Subjects taking zatebradine also had more visual disturbances as adverse reactions.

CONCLUSIONS

Zatebradine seems to provide no additional antianginal benefit to patients already receiving nifedipine, and it raises questions regarding the benefit of heart rate reduction alone as an antianginal approach to patients with chronic stable angina.

A large, prospective, open-label study of isradipine in patients with essential hypertension. The Isradipine Investigators Group

Isradipine is a dihydropyridine calcium-entry blocker. Previous controlled and blinded trials have demonstrated the safety and efficacy of isradipine in lowering blood pressure in patients with hypertension. The purpose of this study was to reassess this safety and efficacy in a large number of patients in an open-label, long-term, multicenter trial. A total of 501 patients with essential hypertension (diastolic blood pressure 95 to 114 mm Hg) received 5 to 10 mg/d of isradipine in two divided doses for a period of 32 weeks. The mean dose used was 7.4 mg/d with titration at week 4 from 5 mg/d (2.5 mg BID) to 10 mg/d (5 mg BID) if the diastolic pressure was still > 90 mm Hg. After 32 weeks of isradipine treatment, systolic blood pressure decreased from 154.9 +/- 16.4 mm Hg to 140.2 +/- 13.9 mm Hg (P < 0.001) and diastolic pressure from 101.2 +/- 5.2 mm Hg to 86.6 +/- 7.9 mm Hg (P < 0.001). This monotherapy was successful in reducing diastolic blood pressure > 10 mm Hg in 62.5% of the patients. Significant adverse effects were noted in 92 (18.4%) of the 501 patients; only 30 (6.0%) withdrew from the study because of adverse events. In this large, long-term, community-based study, isradipine was effective and well tolerated in most patients.

A double-blind, placebo-controlled trial of sustained-release diltiazem in patients with angina. Sustained-Release Diltiazem Study Group

The efficacy of a new sustained-release formulation of diltiazem was examined in a placebo-controlled, double-blind trial in patients with stable angina. Doses of 60 mg BID, 90 mg BID, 180 mg BID and 240 mg BID were compared with placebo in 208 patients at 3 hours and 12 hours after dosing. Diltiazem, in doses of 90 mg BID and 180 mg BID, was statistically superior to placebo with respect to increasing total exercise time. Treadmill exercise time at 3 hours postdose increased with placebo from 356.1 +/- 118.7 sec to 375.7 +/- 119.8 sec (NS); with 90 mg BID, 382.7 +/- 111.8 sec to 445.4 +/- 117.5 sec (P < 0.005); and with 180 mg BID, 386.8 +/- 145.9 sec to 467.2 +/- 166.2 sec (P < 0.0001). At 12 hours postdose, treadmill exercise time with placebo increased from 357.6 +/- 128.3 sec to 383.8 +/- 128.7 sec (NS); with 90 mg BID, 395.2 +/- 119.4 sec to 449.7 +/- 123.1 sec (P = 0.053); with 180 mg BID, 395.3 +/- 141.4 sec to 476.6 +/- 165.6 sec (P < 0.0001). Time to onset of angina was also increased by the 180-mg-BID dose both at 3 hours postdose (257.3 +/- 126.8 sec to 354.3 +/- 158.7 sec; P < 0.0001) and at 12 hours postdose (274.7 +/- 131.2 sec to 377.4 +/- 186.2 sec; P < 0.0001). Sustained-release diltiazem is effective and safe in treating patients with chronic stable angina.

Randomized placebo-controlled trial of amlodipine in vasospastic angina. Amlodipine Study 160 Group

OBJECTIVES

This study was designed to assess the efficacy and safety of amlodipine, a long-acting calcium channel blocker, in patients with vasospastic angina.

BACKGROUND

Previous studies have established the value of short-acting calcium channel blockers in the treatment of coronary spasm.

METHODS

Fifty-two patients with well documented vasospastic angina were entered into the present study. After a single-blind placebo run-in period, patients were randomized (in a double-blind protocol) to receive either amlodipine (10 mg) or placebo every morning for 4 weeks. Twenty-four patients received amlodipine and 28 received placebo. All patients were given diaries in which to record both the frequency, severity, duration and circumstances of anginal episodes and their intake of sublingual nitroglycerin tablets.

RESULTS

The rate of anginal episodes decreased significantly (p = 0.009) with amlodipine treatment compared with placebo and the intake of nitroglycerin tablets showed a similar trend. Peripheral edema was the only adverse event seen more frequently in amlodipine-treated patients. No patient was withdrawn from the double-blind phase of the study because of an adverse event. Patients who completed the double-blind phase as responders to amlodipine or as nonresponders to placebo were offered the option of receiving amlodipine in a long-term, open label extension phase. During the extension, the daily dose of amlodipine was adjusted to 5 or 15 mg if needed and the rate of both anginal episodes and nitroglycerin tablet consumption showed statistically significant decreases between baseline and final assessment.

CONCLUSION

This study suggests that amlodipine given once daily is efficacious and safe in the treatment of vasospastic angina.

Perindopril as monotherapy in hypertension: a multicenter comparison of two dosing regimens. The Perindopril Study Group

Perindopril erbumine, a new long-acting, non-sulfhydryl-containing angiotensin converting enzyme inhibitor, was evaluated in 289 patients with hypertension in a 16-week, double-blind, placebo-controlled dose-ranging study. After 4 weeks of single-blind placebo treatment, patients with supine diastolic arterial pressures from 95 to 114 mm Hg were randomized to receive placebo, 4 mg perindopril once daily, or 2 mg perindopril twice daily. The daily dose of perindopril was increased by 4 mg every 4 weeks to a maximum of 16 mg per day. Mean decreases in systolic and diastolic arterial pressure were greater with perindopril than with placebo (p < 0.05). The dose-response curve flattened after 8 mg per day, and there was no difference in arterial pressure reduction or in the percentage of responders between once- and twice-daily administration of perindopril. Adverse reactions with perindopril were generally mild and, with the exception of cough, were similar with placebo. The findings of this study indicate that perindopril is effective, well tolerated, and suitable for once-daily administration for the treatment of hypertension.

Effects of antihypertensive agents on sexual function

Patient compliance with antihypertensive therapy can be improved by minimizing drug-induced sexual dysfunction. Impotence, decreased libido, impaired ejaculation and gynecomastia are potential side effects, depending on the agent prescribed. Centrally acting antihypertensive agents such as methyldopa and clonidine, nonselective beta-adrenergic blockers and potassium-sparing diuretics are the drugs most often associated with sexual dysfunction. Thiazide diuretics cause impotence but may otherwise play a minimal role in sexual dysfunction. Alpha-adrenergic blockers, angiotensin converting enzyme inhibitors and calcium channel blockers have little adverse effect on sexual function. It is important to obtain an adequate history before and after initiating therapy. If sexual dysfunction develops in a patient, a different class of medication can be tried.

Cardiac microdialysis to estimate interstitial adenosine and coronary blood flow

The purpose of this study was twofold: 1) to investigate the feasibility and usefulness of cardiac microdialysis for the simultaneous estimation of regional cardiac interstitial fluid (ISF) adenosine (ADO) concentration and coronary blood flow (CBF); and 2) to determine the changes in the ISF levels of ADO and CBF during cardiac stimulation or regional myocardial ischemia. Cardiac microdialysis probes were implanted in the left ventricular myocardium of chloralose-urethan-anesthetized dogs and perfused with Krebs-Henseleit buffer. The concentration of ADO in the effluent dialysate was used as an index of intramyocardial ISF ADO concentration while local CBF was measured by H2 clearance via a platinum wire within the dialysis fiber. Dialysate ADO was elevated immediately after insertion of the microdialysis probe, declined rapidly in the first 20 min, stabilized by 60 min, and remained constant for 2 h. Based on the relationship in vitro and in vivo between microdialysis probe perfusion rate and dialysate ADO concentration, ISF ADO concentration within the left ventricular myocardium was estimated to be 0.9-1.3 microM. Dobutamine (10 micrograms.kg-1.min-1) infusion resulted in a 36% increase in CBF and a 2.5-fold increase in dialysate ADO (n = 9; P less than 0.05). Regional myocardial ischemia, induced by occlusion of the left anterior descending artery (LAD), caused a 13-fold increase in dialysate ADO in the LAD perfused myocardium (n = 9; P less than 0.05). These results are consistent with the ADO hypothesis and suggest that cardiac microdialysis provides a reliable technique for the sampling of regional intramyocardial ISF.

A phase II trial of intraperitoneal cisplatin and etoposide for primary treatment of ovarian epithelial cancer

We conducted a phase II trial of intraperitoneal (IP) cisplatin (DDP) and etoposide (VP-16) in stage III and IV newly diagnosed ovarian carcinoma patients with residual disease of any size. Twenty-three patients were entered, 19 had stage III and four stage IV disease. DDP 200 mg/m2 and VP-16 350 mg/m2 were given in 2 L saline IP via a Port-A-Cath (Pharmacia-Deltec, St Paul, MN). Sodium thiosulfate 4 g/m2 was given intravenously (IV) just before the start of IP instillation, and continued as a constant IV infusion of 2 g/m2/hr IV for a total of 6 hours. Treatment was given once every 4 weeks; six cycles of therapy were planned. Thirteen patients (56%) were in complete clinical remission at the end of treatment (normal physical exam, computed tomographic [CT] scan, CA-125, and peritoneal cytology). Seven of these 13 underwent a second-look laparotomy: three (13%) were in pathologic complete remission and four (17%) had microscopic disease only. Projected survival is 68% at 27 months, with 10 patients being alive and continuously free of disease. There was a very rapid fall in mean CA-125 to within normal limits at the end of the second course of treatment. The major toxicity was myelosuppression with median nadir WBC, granulocyte, and platelet counts of 2,600, 896, and 205,000/microL, respectively. There was no cumulative renal damage, anemia, hypomagnesemia, or chemical peritonitis. Neurotoxicity was similar to that observed with IV dosing. We conclude that therapy with the IP DDP/VP-16/IV thiosulfate regimen, in which all cytotoxic drugs are given only by the IP route, produces less anemia and renal damage than standard IV DDP-containing regimens, and that survival with this regimen appears to be at least as good as that produced by IV programs.