Pre-treatment with antiarrhythmic drugs for elective electrical cardioversion of atrial fibrillation: a systematic review and network meta-analysis.

AIMS: Our objective was to compare the efficacy of pre-treatment with different classes of anti-arrhythmic drugs (AADs) in patients with atrial fibrillation (AF) undergoing electrical cardioversion. METHODS AND RESULTS: We performed a systematic review and network meta-analysis (NMA) of randomized controlled trials (RCTs) comparing different AADs in patients with AF undergoing electrical cardioversion. We grouped AADs into five network nodes: no treatment or rate control, Class Ia, Class Ic, Class III, and amiodarone. Outcomes were (i) acute restoration and (ii) maintenance of sinus rhythm. We searched MEDLINE and EMBASE from inception until June 2020. We used Python 3.8.3 and R 3.6.2 for data analysis. We evaluated the overall certainty of evidence with the GRADE framework. We included 28 RCTs. Compared with no treatment or rate control, Class III AADs [odds ratio (OR): 2.41; 95% credible interval (CrI): 1.37 to 4.62, high certainty] and amiodarone (OR: 2.58; 95% CrI: 1.54 to 4.37, high certainty) improved restoration of sinus rhythm. Amiodarone improved long-term maintenance of sinus rhythm when compared with no treatment or rate control (OR: 5.37; 95% CrI: 4.00-7.39, high certainty), Class Ic (OR: 1.89; 95% CrI: 1.05-3.45, moderate certainty) and Class III AADs (OR: 2.19; 95% CrI: 1.39-3.26, high certainty). CONCLUSION: Before electrical cardioversion of AF, treatment with Class III AADs or amiodarone improves the acute restoration of sinus rhythm. Amiodarone is most likely to improve the maintenance of sinus rhythm after electrical cardioversion, but Class Ic and Class III AADs are also effective.

Multicenter Evaluation of the Cepheid Xpert Xpress SARS-CoV-2 Test.

Nucleic acid amplification tests (NAATs) are the primary means of identifying acute infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Accurate and fast test results may permit more efficient use of protective and isolation resources and allow rapid therapeutic interventions. We evaluated the analytical and clinical performance characteristics of the Xpert Xpress SARS-CoV-2 (Xpert) test, a rapid, automated molecular test for SARS-CoV-2. Analytical sensitivity and specificity/interference were assessed with infectious SARS-CoV-2; other infectious coronavirus species, including SARS-CoV; and 85 nasopharyngeal swab specimens positive for other respiratory viruses, including endemic human coronaviruses (hCoVs). Clinical performance was assessed using 483 remnant upper- and lower-respiratory-tract specimens previously analyzed by standard-of-care (SOC) NAATs. The limit of detection of the Xpert test was 0.01 PFU/ml. Other hCoVs, including Middle East respiratory syndrome coronavirus, were not detected by the Xpert test. SARS-CoV, a closely related species in the subgenus Sarbecovirus, was detected by a broad-range target (E) but was distinguished from SARS-CoV-2 (SARS-CoV-2-specific N2 target). Compared to SOC NAATs, the positive agreement of the Xpert test was 219/220 (99.5%), and the negative agreement was 250/261 (95.8%). A third tie-breaker NAAT resolved all but three of the discordant results in favor the Xpert test. The Xpert test provided sensitive and accurate detection of SARS-CoV-2 in a variety of upper- and lower-respiratory-tract specimens. The high sensitivity and short time to results of approximately 45 min may impact patient management.

Pre- and post-treatment with amiodarone for elective electrical cardioversion of atrial fibrillation: a systematic review and meta-analysis.

AIMS: Clinicians frequently pre-treat patients with amiodarone to increase the efficacy of electrical cardioversion for atrial fibrillation (AF). Our objective was to determine the precise effects of amiodarone pre- and post-treatment on conversion efficacy and sinus rhythm maintenance. METHODS AND RESULTS: We conducted a systematic review and meta-analysis of trials comparing pre- and post-treatment for electrical cardioversion with amiodarone vs. no therapy on (i) acute restoration and (ii) maintenance of sinus rhythm after 1 year. We searched MEDLINE and EMBASE from inception to July 2018 for randomized controlled trials. We evaluated the risk of bias for individual studies with the Cochrane tool and overall quality of evidence with the GRADE framework. We identified eight eligible studies (n = 1012). Five studies were deemed to have unclear or high risk of selection bias. We found the evidence to be of high quality based on GRADE. Treatment with amiodarone (200-800 mg daily for 1-6 weeks pre-cardioversion; 0-200 mg daily post-cardioversion) was associated with higher rates of acute restoration [relative risk (RR) 1.22, 95% confidence interval (CI) 1.07-1.39, P = 0.004, n = 1012, I2 = 65%] and maintenance of sinus rhythm over 13 months (RR 4.39, 95% CI 2.99-6.45, P < 0.001, n = 695, I2 = 0%). The effects of amiodarone for acute restoration were maintained when considering only studies at low risk of bias (RR 1.22, 95% CI 1.10-1.36, P < 0.001, n = 572, I2 = 0%). Adverse effects were typically non-serious, occurring in 3.4% (6/174) of subjects receiving amiodarone. CONCLUSION: High-quality evidence demonstrated that treatment with amiodarone improved the restoration and maintenance of sinus rhythm after electrical cardioversion of AF. Short-term amiodarone was well-tolerated.

Decreasing Postoperative Blood Loss by Topical vs. Intravenous Tranexamic Acid in Open Cardiac Surgery (DEPOSITION) study: Results of a pilot study.

BACKGROUND: Cardiac surgery patients are at high risk for postoperative bleeding. Intravenous (IV) tranexamic acid (TxA) is a commonly used antifibrinolytic drug, but is associated with postoperative seizures. We conducted this pilot randomized controlled trial (RCT) to determine the feasibility of a larger trial that will be designed to investigate the impact of TxA administration route, intrapericardial (IP) vs IV, on postoperative bleeding and seizures. METHODS: In this single-center, double-blinded, pilot RCT we enrolled adult patients undergoing nonemergent on-pump cardiac operations through a median sternotomy. Participants were randomized to IP or IV TxA groups. The primary outcomes were cumulative chest tube drainage, transfusion requirements, and incidence of postoperative seizures. RESULTS: A total of 97 participants were randomized to the intervention and control groups. Baseline characteristics were similar in both groups. Most participants underwent a CABG and/or aortic valve replacement. There was no statistical difference. The IP TxA group was found to have a tendency for less chest tube drainage in comparison to the IV TxA group, 500.5 (370.0-700.0) and 540.0 (420.0-700.0) mL, respectively, which was not statistically significant (P = 0.2854). Fewer participants in the IP TxA group with cardiac tamponade and/or required a reoperation for bleeding and fewer packed red blood cell transfusions. None of the IP TxA group developed seizure vs one from the IV TxA group. CONCLUSION: This is the first known pilot RCT to investigate the role of TxA route of administration in open cardiac surgery. Intrapericardial TxA shows promising results with decreased bleeding, transfusion requirements, reoperations, and postoperative seizures. A larger RCT is needed to confirm these results and lead to a change in practice.

Comparison of central laboratory assessments of ER, PR, HER2, and Ki67 by IHC/FISH and the corresponding mRNAs (ESR1, PGR, ERBB2, and MKi67) by RT-qPCR on an automated, broadly deployed diagnostic platform.

PURPOSE: The methods (IHC/FISH) typically used to assess ER, PR, HER2, and Ki67 in FFPE specimens from breast cancer patients are difficult to set up, perform, and standardize for use in low and middle-income countries. Use of an automated diagnostic platform (GeneXpert®) and assay (Xpert® Breast Cancer STRAT4) that employs RT-qPCR to quantitate ESR1, PGR, ERBB2, and MKi67 mRNAs from formalin-fixed, paraffin-embedded (FFPE) tissues facilitates analyses in less than 3 h. This study compares breast cancer biomarker analyses using an RT-qPCR-based platform with analyses using standard IHC and FISH for assessment of the same biomarkers. METHODS: FFPE tissue sections from 523 patients were sent to a College of American Pathologists-certified central reference laboratory to evaluate concordance between IHC/FISH and STRAT4 using the laboratory's standard of care methods. A subset of 155 FFPE specimens was tested for concordance with STRAT4 using different IHC antibodies and scoring methods. RESULTS: Concordance between STRAT4 and IHC was 97.8% for ESR1, 90.4% for PGR, 93.3% for ERBB2 (IHC/FISH for HER2), and 78.6% for MKi67. Receiver operating characteristic curve (ROC) area under the curve (AUC) values of 0.99, 0.95, 0.99, and 0.85 were generated for ESR1, PGR, ERBB2, and MKi67, respectively. Minor variabilities were observed depending on the IHC antibody comparator used. CONCLUSION: Evaluation of breast cancer biomarker status by STRAT4 was highly concordant with central IHC/FISH in this blinded, retrospectively analyzed collection of samples. STRAT4 may provide a means to cost-effectively generate standardized diagnostic results for breast cancer patients in low- and middle-income countries.

High concordance of a closed-system, RT-qPCR breast cancer assay for HER2 mRNA, compared to clinically determined immunohistochemistry, fluorescence in situ hybridization, and quantitative immunofluorescence.

Historically, mRNA measurements have been tested on several commercially available platforms, but none have gained broad acceptance for assessment of HER2. An mRNA measurement, as a continuous value, has the potential for use in adjudication of the equivocal category. Here we use a real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) assay in a closed, single-use cartridge, automated system. Multiple cores (1 mm in diameter) were retrospectively collected from 80 formalin-fixed paraffin-embedded (FFPE) tissue blocks with invasive breast cancer seen by Yale Pathology Labs between 1998 and 2011. Tissue cores were processed with a FFPE lysis kit to create lysates that were tested with the automated RT-qPCR assay. Results for IHC and FISH were extracted from the pathology reports and quantitative immunofluorescence (QIF) for each case was measured as previously described. Quality control testing showed that the GX platform RT-qPCR shows no case to case cross contamination on material from routine histology practices. Concordance between RT-qPCR and IHC/FISH was 91.25% (sensitivity=0.87; specificity=0.94; PPV=0.89; NPV=0.92) using a pre-defined delta Ct cut-off (dCt≥-1) for HER2. Concordance (OPA) between RT-qPCR and QIF was 94% (sensitivity=0.90; specificity=0.96; PPV=0.93; NPV=0.94) using dCt≥-1 and a previously defined cut-point for positivity by QIF. In conclusion, the closed system RT-qPCR assay shows >90% concordance with the ASCO/CAP HER2 IHC/FISH scoring. Additionally, the RT-qPCR assay is highly concordant (94%) with the continuous variable HER2 QIF assay, and may better reflect the true continuum of HER2 receptor status in invasive breast cancer. These initial results suggest that fast, closed system molecular assays may have future value for the adjudication of the ASCO/CAP HER2 equivocal category or possibly routine usage in time constrained or low resource settings.

Oral administration of obeldesivir protects nonhuman primates against Sudan ebolavirus.

Obeldesivir (ODV, GS-5245) is an orally administered prodrug of the parent nucleoside of remdesivir (RDV) and is presently in phase 3 trials for COVID-19 treatment. In this work, we show that ODV and its circulating parent nucleoside metabolite, GS-441524, have similar in vitro antiviral activity against filoviruses, including Marburg virus, Ebola virus, and Sudan virus (SUDV). We also report that once-daily oral ODV treatment of cynomolgus monkeys for 10 days beginning 24 hours after SUDV exposure confers 100% protection against lethal infection. Transcriptomics data show that ODV treatment delayed the onset of inflammation and correlated with antigen presentation and lymphocyte activation. Our results offer promise for the further development of ODV to control outbreaks of filovirus disease more rapidly.

Characterization of the Cynomolgus Macaque Model of Marburg Virus Disease and Assessment of Timing for Therapeutic Treatment Testing.

Marburg virus (MARV) causes severe disease and high mortality in humans. The objective of this study was to characterize disease manifestations and pathogenesis in cynomolgus macaques exposed to MARV. The results of this natural history study may be used to identify features of MARV disease useful in defining the ideal treatment initiation time for subsequent evaluations of investigational therapeutics using this model. Twelve cynomolgus macaques were exposed to a target dose of 1000 plaque-forming units MARV by the intramuscular route, and six control animals were mock-exposed. The primary endpoint of this study was survival to Day 28 post-inoculation (PI). Anesthesia events were minimized with the use of central venous catheters for periodic blood collection, and temperature and activity were continuously monitored by telemetry. All mock-exposed animals remained healthy for the duration of the study. All 12 MARV-exposed animals (100%) became infected, developed illness, and succumbed on Days 8-10 PI. On Day 4 PI, 11 of the 12 MARV-exposed animals had statistically significant temperature elevations over baseline. Clinically observable signs of MARV disease first appeared on Day 5 PI, when 6 of the 12 animals exhibited reduced responsiveness. Ultimately, systemic inflammation, coagulopathy, and direct cytopathic effects of MARV all contributed to multiorgan dysfunction, organ failure, and death or euthanasia of all MARV-exposed animals. Manifestations of MARV disease, including fever, systemic viremia, lymphocytolysis, coagulopathy, and hepatocellular damage, could be used as triggers for initiation of treatment in future therapeutic efficacy studies.

Activation of the SARS coronavirus spike protein via sequential proteolytic cleavage at two distinct sites.

The coronavirus spike protein (S) plays a key role in the early steps of viral infection, with the S1 domain responsible for receptor binding and the S2 domain mediating membrane fusion. In some cases, the S protein is proteolytically cleaved at the S1-S2 boundary. In the case of the severe acute respiratory syndrome coronavirus (SARS-CoV), it has been shown that virus entry requires the endosomal protease cathepsin L; however, it was also found that infection of SARS-CoV could be strongly induced by trypsin treatment. Overall, in terms of how cleavage might activate membrane fusion, proteolytic processing of the SARS-CoV S protein remains unclear. Here, we identify a proteolytic cleavage site within the SARS-CoV S2 domain (S2', R797). Mutation of R797 specifically inhibited trypsin-dependent fusion in both cell-cell fusion and pseudovirion entry assays. We also introduced a furin cleavage site at both the S2' cleavage site within S2 793-KPTKR-797 (S2'), as well as at the junction of S1 and S2. Introduction of a furin cleavage site at the S2' position allowed trypsin-independent cell-cell fusion, which was strongly increased by the presence of a second furin cleavage site at the S1-S2 position. Taken together, these data suggest a novel priming mechanism for a viral fusion protein, with a critical proteolytic cleavage event on the SARS-CoV S protein at position 797 (S2'), acting in concert with the S1-S2 cleavage site to mediate membrane fusion and virus infectivity.

Use of the Xpert Breast Cancer STRAT4 for Biomarker Evaluation in Tissue Processed in a Developing Country.

OBJECTIVES: Breast cancer immunohistochemistry (IHC) biomarker testing is limited in low-resource settings, and an alternative solution is needed. A point-of-care mRNA STRAT4 breast cancer assay for ESR1, PGR, ERBB2, and MKi67, for use on the GeneXpert platform, has been recently validated on tissues from internationally accredited laboratories, showing excellent concordance with IHC. METHODS: We evaluated STRAT4/IHC ESR1/estrogen receptor (ER), ERBB2/human epidermal growth factor receptor 2 (HER2) concordance rates of 150 breast cancer tissues processed in Rwanda, with undocumented cold ischemic and fixation time. RESULTS: Assay fail/indeterminate rate was 2.6% for ESR1 and ERBB2. STRAT4 agreement with ER IHC was 92.5% to 93.3% and 97.8% for HER2, for standard (1x) and concentrated (4x) reagent-conserving protocols, respectively. Eleven of 12 discordant ER/ESR1 cases were ESR1- negative/IHC-positive. These had low expression of ER by IHC in mostly very small tumor areas tested (7/12; <25 mm2). In two of three discordant HER2 cases, the STRAT4-ERBB2 result correlated with the subsequent fluorescence in situ hybridization (FISH) result. STRAT4-ERBB2 results in 9 of 10 HER2-IHC equivocal cases were concordant with FISH. CONCLUSIONS: The STRAT4 assay is an alternative for providing quality-controlled breast cancer biomarker data in laboratories unable to provide quality and/or cost-efficient IHC services.

A Multitask Deep-Learning System to Classify Diabetic Macular Edema for Different Optical Coherence Tomography Devices: A Multicenter Analysis.

OBJECTIVE: Diabetic macular edema (DME) is the primary cause of vision loss among individuals with diabetes mellitus (DM). We developed, validated, and tested a deep learning (DL) system for classifying DME using images from three common commercially available optical coherence tomography (OCT) devices. RESEARCH DESIGN AND METHODS: We trained and validated two versions of a multitask convolution neural network (CNN) to classify DME (center-involved DME [CI-DME], non-CI-DME, or absence of DME) using three-dimensional (3D) volume scans and 2D B-scans, respectively. For both 3D and 2D CNNs, we used the residual network (ResNet) as the backbone. For the 3D CNN, we used a 3D version of ResNet-34 with the last fully connected layer removed as the feature extraction module. A total of 73,746 OCT images were used for training and primary validation. External testing was performed using 26,981 images across seven independent data sets from Singapore, Hong Kong, the U.S., China, and Australia. RESULTS: In classifying the presence or absence of DME, the DL system achieved area under the receiver operating characteristic curves (AUROCs) of 0.937 (95% CI 0.920-0.954), 0.958 (0.930-0.977), and 0.965 (0.948-0.977) for the primary data set obtained from CIRRUS, SPECTRALIS, and Triton OCTs, respectively, in addition to AUROCs >0.906 for the external data sets. For further classification of the CI-DME and non-CI-DME subgroups, the AUROCs were 0.968 (0.940-0.995), 0.951 (0.898-0.982), and 0.975 (0.947-0.991) for the primary data set and >0.894 for the external data sets. CONCLUSIONS: We demonstrated excellent performance with a DL system for the automated classification of DME, highlighting its potential as a promising second-line screening tool for patients with DM, which may potentially create a more effective triaging mechanism to eye clinics.

Comparison of Heart Team vs Interventional Cardiologist Recommendations for the Treatment of Patients With Multivessel Coronary Artery Disease.

Importance: Although the heart team approach is recommended in revascularization guidelines, the frequency with which heart team decisions differ from those of the original treating interventional cardiologist is unknown. Objective: To examine the difference in decisions between the heart team and the original treating interventional cardiologist for the treatment of patients with multivessel coronary artery disease. Design, Setting, and Participants: In this cross-sectional study, 245 consecutive patients with multivessel coronary artery disease were recruited from 1 high-volume tertiary care referral center (185 patients were enrolled through a screening process, and 60 patients were retrospectively enrolled from the center's database). A total of 237 patients were included in the final virtual heart team analysis. Treatment decisions (which comprised coronary artery bypass grafting, percutaneous coronary intervention, and medication therapy) were made by the original treating interventional cardiologists between March 15, 2012, and October 20, 2014. These decisions were then compared with pooled-majority treatment decisions made by 8 blinded heart teams using structured online case presentations between October 1, 2017, and October 15, 2018. The randomized members of the heart teams comprised experts from 3 domains, with each team containing 1 noninvasive cardiologist, 1 interventional cardiologist, and 1 cardiovascular surgeon. Cases in which all 3 of the heart team members disagreed and cases in which procedural discordance occurred (eg, 2 members chose coronary artery bypass grafting and 1 member chose percutaneous coronary intervention) were discussed in a face-to-face heart team review in October 2018 to obtain pooled-majority decisions. Data were analyzed from May 6, 2019, to April 22, 2020. Main Outcomes and Measures: The Cohen κ coefficient between the treatment recommendation from the heart team and the treatment recommendation from the original treating interventional cardiologist. Results: Among 234 of 237 patients (98.7%) in the analysis for whom complete data were available, the mean (SD) age was 67.8 (10.9) years; 176 patients (75.2%) were male, and 191 patients (81.4%) had stenosis in 3 epicardial coronary vessels. A total of 71 differences (30.3%; 95% CI, 24.5%-36.7%) in treatment decisions between the heart team and the original treating interventional cardiologist occurred, with a Cohen κ of 0.478 (95% CI, 0.336-0.540; P = .006). The heart team decision was more frequently unanimous when it was concordant with the decision of the original treating interventional cardiologist (109 of 163 cases [66.9%]) compared with when it was discordant (28 of 71 cases [39.4%]; P < .001). When the heart team agreed with the original treatment decision, there was more agreement between the heart team interventional cardiologist and the original treating interventional cardiologist (138 of 163 cases [84.7%]) compared with when the heart team disagreed with the original treatment decision (14 of 71 cases [19.7%]); P < .001). Those with an original treatment of coronary artery bypass grafting, percutaneous coronary intervention, and medication therapy, 32 of 148 patients [22.3%], 32 of 71 patients [45.1%], and 6 of 15 patients [40.0%], respectively, received a different treatment recommendation from the heart team than the original treating interventional cardiologist; the difference across the 3 groups was statistically significant (P = .002). Conclusions and Relevance: The heart team's recommended treatment for patients with multivessel coronary artery disease differed from that of the original treating interventional cardiologist in up to 30% of cases. This subset of cases was associated with a lower frequency of unanimous decisions within the heart team and less concordance between the interventional cardiologists; discordance was more frequent when percutaneous coronary intervention or medication therapy were considered. Further research is needed to evaluate whether heart team decisions are associated with improvements in outcomes and, if so, how to identify patients for whom the heart team approach would be beneficial.

Management of patients on bisphosphonates and prevention of bisphosphonate-related osteonecrosis of the jaw.

Bisphosphonate related osteonecrosis of the jaw (BRONJ) is a recent discovery and has only been brought to the attention of health care professionals in since 2003. The purpose of this article is to describe this phenomenon and focus on preventive strategies to minimize the risk of patients developing this condition. Management and prevention will be broken down into patients taking IV bisphosphonates and patients taking oral bisphosphonates.

Avoiding S3 Valve Over-Sizing by Deployment Balloon Over-Filling: Impact on Rates of Permanent Pacemaker and Other Procedural Complications During TAVR.

OBJECTIVES: Patients with annular areas just above nominal S3 valve areas are at increased risk of over-sizing if a larger valve is implanted. We therefore evaluated the rate of permanent pacemaker (PPM) implantation associated with avoiding over-sizing by selective deployment balloon over-filling during transcatheter aortic valve replacement (TAVR) with the Sapien 3 (S3) valve. METHODS: We included consecutive patients treated with the S3 valve from January 2016 to May 2017. We identified computed tomography annular areas where the nominally deployed valve would be over-sized by >12%-15% (areas 340-360 mm² for 23 mm valve, 420-450 mm² for 26 mm valve, 530-580 mm² for 29 mm valve) as those at highest risk for valve over-sizing. In these situations, we used the smaller valve and over-filled the deployment balloon to achieve a predicted valve area/annular area ratio of approximately 1. For annular areas >650 mm², we over-filled the 29 mm valve to achieve a similar ratio. RESULTS: We evaluated 102 patients (59 males; mean age, 83.7 ± 6.5 years; mean STS score, 10.2). Over-filling of the deployment balloon was used in 35 cases (34%). We observed a post-TAVR PPM rate of 6.9% overall and 2.7% among the 75 patients without pre-TAVR right bundle-branch block (RBBB). Cases with valve over-filling vs nominal deployment had infrequent need for postdilation (14.3% vs 6.0%, respectively; P=.17) and similar postprocedure gradients (9.9 mm Hg vs 10.3 mm Hg, respectively; P=.59). CONCLUSION: A strategy to avoid S3 valve over-sizing by selective deployment balloon over-filling was associated with a low rate of PPM, especially in patients without pre-existing RBBB.

Feline aminopeptidase N is not a functional receptor for avian infectious bronchitis virus.

BACKGROUND: Coronaviruses are an important cause of infectious diseases in humans, including severe acute respiratory syndrome (SARS), and have the continued potential for emergence from animal species. A major factor in the host range of a coronavirus is its receptor utilization on host cells. In many cases, coronavirus-receptor interactions are well understood. However, a notable exception is the receptor utilization by group 3 coronaviruses, including avian infectious bronchitis virus (IBV). Feline aminopeptidase N (fAPN) serves as a functional receptor for most group 1 coronaviruses including feline infectious peritonitis virus (FIPV), canine coronavirus, transmissible gastroenteritis virus (TGEV), and human coronavirus 229E (HCoV-229E). A recent report has also suggested a role for fAPN during IBV entry (Miguel B, Pharr GT, Wang C: The role of feline aminopeptidase N as a receptor for infectious bronchitis virus. Brief review. Arch Virol 2002, 147:2047-2056. RESULTS: Here we show that, whereas both transient transfection and constitutive expression of fAPN on BHK-21 cells can rescue FIPV and TGEV infection in non-permissive BHK cells, fAPN expression does not rescue infection by the prototype IBV strain Mass41. To account for the previous suggestion that fAPN could serve as an IBV receptor, we show that feline cells can be infected with the prototype strain of IBV (Mass 41), but with low susceptibility compared to primary chick kidney cells. We also show that BHK-21 cells are slightly susceptible to certain IBV strains, including Ark99, Ark_DPI, CA99, and Iowa97 (<0.01% efficiency), but this level of infection is not increased by fAPN expression. CONCLUSION: We conclude that fAPN is not a functional receptor for IBV, the identity of which is currently under investigation.

Heparan sulfate is a selective attachment factor for the avian coronavirus infectious bronchitis virus Beaudette.

The avian coronavirus infectious bronchitis virus (IBV) strain Beaudette is an embryo-adapted virus that has extended species tropism in cell culture. In order to understand the acquired tropism of the Beaudette strain, we compared the S protein sequences of several IBV strains. The Beaudette strain was found to contain a putative heparan sulfate (HS)-binding site, indicating that the Beaudette virus may use HS as a selective receptor. To ascertain the requirements of cell-surface HS for Beaudette infectivity, we assayed for infectivity in the presence of soluble heparin as a competitor and determined infectivity in mutant cell lines with no HS or glycosaminoglycan expression. Our results indicate that HS plays a role as an attachment factor for IBV, working in concert with other factors like sialic acid to mediate virus binding to cells, and may explain in part the extended tropism of IBV Beaudette.

Membrane potassium currents in human radial artery and their regulation by nitric oxide donor.

OBJECTIVE: The human radial artery has demonstrated superior long-term results as a graft in coronary bypass surgery, but undesirable post-surgical spasm limits its clinical application. Few have examined its excitatory properties, especially the underlying ion channel mechanisms. In this study, we investigated the kinetic and pharmacological properties of the smooth muscle membrane potassium currents of this important artery. METHODS AND RESULTS: Using whole cell patch-clamp techniques, we found the K(+) current to be voltage-dependent and outwardly rectifying. Voltage-dependent inactivation was observed, being half-maximal at +28.0 mV but incomplete even at +40 mV. The K(+) currents were predominantly sensitive to the K(Ca) blocker tetraethylammonium (TEA; 63.9+/-12.1% inhibition, p<0.05), less sensitive to the Kv blocker 4-aminopyridine (4-AP; 32.8+/-4.4% inhibition, p<0.05), and the K(ATP) blocker glibenclamide (28.7+/-8.5% inhibition), at -20 mV testing potential. Resting membrane potential was -52.0+/-6.8 mV (n=5), and suppression of K(+) currents by TEA and iberiotoxin (IbTx) caused membrane depolarization. Western blot analysis with channel-specific antibodies confirmed the presence of K(Ca) and Kv channel proteins. TEA evoked 20.7+/-9.9% of the contractile response to 60 mM KCl, whereas IbTx caused about 10% of the above response at 10(-7) M. The nitric oxide donor SNAP augmented membrane K(+) currents in a concentration-dependent fashion; the augmentation was completely suppressed by TEA, but was relatively insensitive to the guanylate cyclase inhibitor ODQ. CONCLUSIONS: The radial artery manifests mainly Ca(2+)-dependent K(+) currents at rest; this current is augmented by nitric oxide through a cGMP- and protein kinase G-independent action. The relatively depolarized membrane potential, as well as its muscular structure, predisposes the radial artery to spasm. Agents that activate the Ca(2+)-dependent K(+) current could be of therapeutic value in preventing post-surgical vasospasm.