tbuckley/cabot-search huggingface dataset:
Letter by Zhang Regarding Article, “Early Dual Versus Mono Antiplatelet Therapy for Acute Non-Cardioembolic Ischemic Stroke or Transient Ischemic Attack: An Updated Systematic Review and Meta-Analysis”
Authors: Hong Zhang
Journal: Circulation (2014)

An Updated Systematic Review and Meta-Analysis" by Wong and colleagues 1 with great interest.In this meta-analysis, the authors included 14 randomized, controlled trials (9012 patients) comparing dual versus mono antiplatelet therapy for acute noncardioembolic ischemic stroke or transient ischemic attack (TIA) within 3 days of ictus.They found that when compared with mono antiplatelet therapy, dual therapy was associated with a reduction in stroke recurrence, and composite vascular events, but without a significant increase in the risk of major bleeding.As the authors state, they included the CHANCE (Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events) trial, 2 which accounted for ≈50% of participants (5170 patients) in this meta-analysis, and is a randomized, double-blind, multicenter, placebo-controlled trial designed to test efficacy and safety for clopidogrel plus aspirin against aspirin alone in the prevention of recurrent stroke in Chinese patients with acute minor stroke or TIA.We wonder whether this meta-analysis may help to modify current Chinese guidelines for stroke, or whether it is the best CHANCE for Chinese with minor ischemic stroke or TIA in the real-world clinical practice?After a TIA or stroke, patients are at a high risk of experiencing recurrent stroke, which will aggravate stroke-related neurological deficit and sometimes even lead to death.Antiplatelet therapy is a major strategy for preventing recurrent stroke in patients with stroke or TIA, as recommended by some guidelines for the control of stroke, such as those formulated by the Chinese Guideline for Stroke, the American Stroke Association, and the American Heart Association.These guidelines suggested aspirin, clopidogrel, and the combined use of aspirin and extended-release dipyridamole as acceptable alternatives for initial therapy.In Asia, dissatisfaction with poststroke recovery has led many to opt for complementary and alternative therapies.Traditional Chinese herb medicine (TCM) is 1 of the dominant forms of complementary and alternative therapies for many Asian populations, including those who have migrated to Western countries.Pharmacological studies have indicated that some TCM can be used for dilating the cardiocerebral vessels, suppressing
Serum antioxidants and myocardial infarction. Are low levels of carotenoids and alpha-tocopherol risk factors for myocardial infarction?
Authors: D AStreet, G WComstock, R MSalkeld, WSchüep, M JKlag
Journal: Circulation (1994)

BACKGROUNDIn vitro, animal and epidemiological studies suggest that lipoprotein oxidation may play an important role in atherosclerosis. Antioxidants may protect against lipoprotein oxidation and in that way inhibit atherosclerosis and its clinical sequelae. To investigate this possibility, we examined the association between levels of several antioxidants and myocardial infarction using serum specimens collected 7 to 14 years before the onset of myocardial infarction.METHODS AND RESULTSA nested case-control design was used. Cases and control subjects were selected from the 25,802 persons who had donated 15 mL of blood in 1974 for a serum bank. Cases comprised 123 persons with a subsequent first diagnosis of myocardial infarction who ranged from 23 through 58 years of age in 1974 and who had had their first diagnosis of myocardial infarction during 1981 to 1988. Two groups of control subjects matched to the cases for sex and age were selected from donors to the serum bank, one from those with hospital adm...
Abstract 17097: A Novel Method to Estimate the True Aortic Valve Effective Orifice Area Using Valve Resistance in Routine Clinical Echocardiography
Authors: Hideaki Kanzaki, Makoto Amaki, Atsushi Okada, Takuya Hasegawa, Yasuhiro Hamatani, Hiroyuki Takahama, Yasuo Sugano, Satoshi Yasuda, Toshihisa Anzai
Journal: Circulation (2017)

Introduction: To determine the true effective orifice area (EOA) in aortic stenosis (AS), ideally, a transvalvular volume flow rate (TVFR) of ≥250 ml/s is required. EOA is underestimated in patient...
Correlation of plasma serotonin changes with platelet aggregation in an in vivo dog model of spontaneous occlusive coronary thrombus formation.
Authors: C RBenedict, BMathew, K ARex, JCartwright, L ASordahl
Journal: Circulation Research (1986)

The role of platelets in contributing to occlusive coronary artery thrombus formation remains unresolved. A large number of studies have utilized in vitro techniques to study platelet aggregation. This report describes a model of spontaneous in vivo thrombus formation which involves application of current in the left circumflex coronary artery of the dog. Changes in mean coronary blood flow velocity (50% above control) are used to predict the point at which current can be discontinued without interrupting the ongoing process of thrombus formation. Thrombus formation proceeds to total vessel occlusion within 62 +/- 18 minutes after discontinuation of current. Coronary sinus plasma serotonin concentrations are used as an in vivo index of platelet aggregation during thrombus formation. Plasma serotonin levels increased only slightly above baseline levels during initial thrombus formation. Coronary sinus serotonin levels rose markedly after cessation of current, reaching a peak just prior to total vessel occl...
Diagnostic accuracy of deep learning in medical imaging: a systematic review and meta-analysis
Authors: Ravi Aggarwal, Viknesh Sounderajah, Guy Martin, Daniel S. W. Ting, Alan Karthikesalingam, Dominic King, Hutan Ashrafian, Ara Darzi
Journal: npj Digital Medicine (2021)

Deep learning (DL) has the potential to transform medical diagnostics. However, the diagnostic accuracy of DL is uncertain. Our aim was to evaluate the diagnostic accuracy of DL algorithms to identify pathology in medical imaging. Searches were conducted in Medline and EMBASE up to January 2020. We identified 11,921 studies, of which 503 were included in the systematic review. Eighty-two studies in ophthalmology, 82 in breast disease and 115 in respiratory disease were included for meta-analysis. Two hundred twenty-four studies in other specialities were included for qualitative review. Peer-reviewed studies that reported on the diagnostic accuracy of DL algorithms to identify pathology using medical imaging were included. Primary outcomes were measures of diagnostic accuracy, study design and reporting standards in the literature. Estimates were pooled using random-effects meta-analysis. In ophthalmology, AUC's ranged between 0.933 and 1 for diagnosing diabetic retinopathy, age-related macular degeneration and glaucoma on retinal fundus photographs and optical coherence tomography. In respiratory imaging, AUC's ranged between 0.864 and 0.937 for diagnosing lung nodules or lung cancer on chest X-ray or CT scan. For breast imaging, AUC's ranged between 0.868 and 0.909 for diagnosing breast cancer on mammogram, ultrasound, MRI and digital breast tomosynthesis. Heterogeneity was high between studies and extensive variation in methodology, terminology and outcome measures was noted. This can lead to an overestimation of the diagnostic accuracy of DL algorithms on medical imaging. There is an immediate need for the development of artificial intelligence-specific EQUATOR guidelines, particularly STARD, in order to provide guidance around key issues in this field.
Assessment of effects of autonomic stimulation and blockade on the signal-averaged electrocardiogram.
Authors: J JGoldberger, M WAhmed, M AParker, A HKadish
Journal: Circulation (1994)

BACKGROUNDSignal-averaged ECG is a noninvasive test designed to detect late potentials. The effects of alterations in autonomic tone on the signal-averaged ECG have not been evaluated systematically.METHODS AND RESULTSThe effects of autonomic stimulation and blockade on the signal-averaged ECG were evaluated in 14 healthy subjects (8 men and 6 women; age, 28.5 +/- 4.8 years) on 2 separate days. The signal-averaged ECG was recorded at baseline and after physiological and pharmacologic beta-adrenergic stimulation (tilt, exercise, and epinephrine and isoproterenol infusions), sequential and combined beta-adrenergic and parasympathetic blockade, and alpha-adrenergic stimulation before and after parasympathetic blockade. Analysis was performed with a bidirectional filter (40-Hz high-pass). Significant changes in the signal-averaged QRS duration from baseline (105.1 +/- 12.0 milliseconds) were noted with tilt (96.8 +/- 8.8 milliseconds), tilt after double blockade (97.5 +/- 9.0 milliseconds), epinephrine (110...
Hemodynamic effects of vasodilator agents in dogs with experimental ventricular septal defects.
Authors: D PSynhorst, R MLauer, D BDoty, M JBrody
Journal: Circulation (1976)

The ratio of pulmonary to systemic vascular resistance (Rp/Rs) largely determines the amount of left-to-right shunting and pulmonary to systemic flow rat (Qp/Qs) in the presence of a large isolated ventricular septal defect. The possibility that pharmacologic reduction of systemic vascular resistance with alpha-adrenergic receptor blockade or beta-adrenergic receptor stimulation would increase the ratio Rp/Rs, and therefore reduce the ratio Qp/Qs, was studied in dogs in which ventricular septal defects had been surgically created. Administration of phentolamine and phenoxybenzamine caused a 42% reduction in Rs and no reduction in Rp. Qs was unchanged and Qp declined by 24% and the ratio Qp/Qs fell by 32%. Infusion of the beta-adrenergic receptor stimulant isoproterenol also reduced Qp/Qs. However, this was accomplished as a result of an increase in Qs and at the expense of an increase in heart rate. As a decline in the ratio Qp/Qs has been shown to be beneficial to patients with large left-to-right shunts...
Radiofrequency catheter ablation guided by intracardiac echocardiography.
Authors: EChu, A PFitzpatrick, M CChin, KSudhir, P GYock, M DLesh
Journal: Circulation (1994)

BACKGROUNDRadiofrequency catheter ablation requires precise positioning of the ablation electrode. Fluoroscopically guided catheter manipulation has limitations, and there are risks of radiation exposure. The purpose of this study was to examine the feasibility of guiding catheter ablation within the right atrium with catheter-based intracardiac echocardiography.METHODS AND RESULTSA 10F, 10-MHz intracardiac imaging catheter was used to direct an ablation electrode at four or five anatomic landmarks in the right atrium. Thirty-eight radiofrequency energy applications were performed in nine anesthetized dogs, and 38 lesions were identified on pathological examination. Lesions were created a mean of 1.9 +/- 2.1 mm from the ultrasound-guided site. Twenty-six of 38 lesions (68%) were less than 2.2 mm from the imaged site. Intracardiac echocardiography also was used to confirm stable electrode-endocardial contact in 37 energy applications (97%) and identified catheter movement in 9 energy applications (24%). Di...
Receptor-effector coupling pathway for alpha 1-adrenergic modulation of abnormal automaticity in 'ischemic' canine Purkinje fibers.
Authors: E PAnyukhovsky, S FSteinberg, I SCohen, M RRosen
Journal: Circulation Research (1994)

We studied the receptor-effector coupling mechanism responsible for alpha 1-adrenergic receptor-induced increases in abnormal automaticity (AA) occurring at low membrane potentials in ischemic Purkinje fibers, superfused with Tyrode's solution containing [K+]o 10 mmol/L, pH 6.8, PO2 < 25 mm Hg. To exclude beta-adrenergic actions, propranolol was added to all solutions. We derived membrane slope resistance (Rsl) from the current-voltage relation obtained with two microelectrodes for intracellular current injection and transmembrane voltage recording. We also measured the membrane time constant, Tm, to assess changes in membrane resistance (Rm). Phenylephrine effects on Rsl in simulated ischemia were studied in the absence or presence of the alpha 1-subtype blockers WB 4101 (WB) or chloroethylclonidine (CEC), both 0.1 mumol/L, and in Purkinje fibers from dogs injected with pertussis toxin (PTX) (30 micrograms/kg i.v., 60 to 72 hours before study). There were no significant differences in mean values of Rs...
Left atrial contribution to ventricular filling during the course of evolving heart failure.
Authors: TKono, H NSabbah, HRosman, MAlam, P DStein, SGoldstein
Journal: Circulation (1992)

BACKGROUNDAbnormal left ventricular (LV) filling has been observed in patients with heart failure and is characterized by marked heterogeneity of mitral inflow velocity. In the present study, the contribution of the left atrium to LV filling was examined in eight dogs during the course of evolving heart failure.METHODS AND RESULTSHeart failure was produced by multiple sequential intracoronary embolizations with microspheres. Pulsed Doppler echocardiography was used to measure mitral inflow velocity at baseline, before embolization, and at 3, 8, 15, 23, and 33 weeks after initiation of microembolization. The early rapid LV filling (Ei) and late left atrial filling (Ai) components were quantitated based on the time-velocity integral of the early and late mitral inflow velocity waveforms, respectively. Ei decreased progressively from 7.6 +/- 1.5 cm at baseline to 4.0 +/- 0.4 cm at 33 weeks (p less than 0.01). In contrast, Ai initially increased from 1.8 +/- 0.9 cm at baseline to 2.7 +/- 0.4 cm at 3 weeks (p ...
Abstract 16179: Coronary Artery Disesae in Hypoplastic Left Heart Syndrome Following Staged Palliation
Authors: Sruti Rao, Salima Bhimani, Lourdes R Prieto, Rukmini R Komarlu
Journal: Circulation (2019)

Introduction: Coronary artery abnormalities are known to occur in hypoplastic left heart syndrome (HLHS), especially in patients (pts) with aortic atresia (AA)/mitral stenosis (MS) group. Coronary ...
Multiple pathways of capillary permeability.
Authors: E MRenkin
Journal: Circulation Research (1977)

Morphological and physiological studies indicate multiple routes for transport across capillary endothelium. However, the identification of the morphological counterparts of specific transport processes (or the assignment of specific transport roles to morphologically identifiable pathways) has been only partly achieved: the contribution of endothelial cell membranes to transport of water and small, lipid-insoluble molecules needs to be evaluated. The identification of the small pore pathway for water and lipid-insoluble molecules with the intercellular junctions still remains questionable. The contributions to total macromolecular transport of junctions, single vesicles (pinocytosis, cytopempsis), chains of vesicles, and fenestrae are not yet known.
Different effects of strenuous exercise and moderate exercise on platelet function in men.
Authors: J SWang, C JJen, H CKung, L JLin, T RHsiue, H IChen
Journal: Circulation (1994)

BACKGROUNDPlatelets play an important role in the pathogenesis of cardiovascular diseases. It is also noticed that on one hand, regular exercise can reduce the risk of cardiovascular diseases, and on the other hand, vigorous exercise provokes sudden cardiac death. We therefore hypothesize that various intensities of exercise may affect platelet function differently.METHODS AND RESULTSStrenuous and moderate exercise (about 50% to 55% of peak oxygen consumption, VO2peak) on a bicycle ergometer in 10 sedentary and 10 physically active healthy young men was executed on two separate occasions. Blood samples were collected before and immediately after exercise. A newly designed tapered parallel plate chamber was used to assess platelet adhesiveness. Platelet aggregation induced by ADP was evaluated by the percentage of reduction in single platelet count. beta-Thromboglobulin (beta-TG) and platelet factor 4 (PF4) were measured by ELISA. In addition, a similar study on 5 patients with stable angina were also cond...
Arteriolar control of capillary cell flow in striated muscle.
Authors: T ESweeney, I HSarelius
Journal: Circulation Research (1989)

This study tests the hypothesis that capillary perfusion is controlled in groups rather than at the level of the individual capillary. We measured cell flux (using cells labeled with substituted tetramethyl rhodamine isothiocyanate, XRITC) and vessel diameter in adjoining arterioles of the terminal vasculature of hamster cremaster muscle (Nembutal, 70 mg/kg i.p.) during rest and hyperemia (10(-4) M adenosine). In terminal arterioles (TAs), 32 of 68 vessels showed cell flux increases from rest to hyperemia exceeding 25 times (i.e., 47% of TAs were relatively unperfused at rest). In vessels feeding TAs (TAFs), 33 of 95 (34%) were relatively unperfused at rest. Cell flux heterogeneity in TAFs decreased significantly by 27% from rest to hyperemia; the corresponding decrease (16%) in TAs was not significant. Thus, unperfused TAFs are present in a proportion which reflects capillary recruitment in hamster cremaster (Sarelius et al, Am J Physiol 1981;241:H317) while TAs are not, and TAFs independently modulate f...
Different functions of the platelet-derived growth factor-alpha and -beta receptors for the migration and proliferation of cultured baboon smooth muscle cells.
Authors: NKoyama, C EHart, A WClowes
Journal: Circulation Research (1994)

Migration of medial smooth muscle cells (SMCs) and their proliferation in the intima contribute to thickening of injured and atherosclerotic vessels. These events have been proposed to be regulated in part by platelet-derived growth factor (PDGF). Two separate PDGF receptors have been identified, PDGF-R alpha and PDGF-R beta. To study the functions of PDGF-R alpha and PDGF-R beta in vascular SMCs, neutralizing monoclonal antibodies (mAbs) specific for each of the two receptors were used. These antibodies allowed us to evaluate the role of each receptor for PDGF-induced proliferation and migration of cultured baboon SMCs. Both PDGF-AA and PDGF-BB stimulated SMC growth, with PDGF-BB being more potent than PDGF-AA. Studies with anti-PDGF-R alpha and anti-PDGF-R beta mAbs revealed that both PDGF receptors promoted the stimulatory signals for proliferation. In contrast, PDGF-BB stimulated SMC migration, whereas PDGF-AA had no stimulatory activity on its own. Additionally, PDGF-AA was able to suppress migration...
Cancer of the Prostate
Authors: Timothy J. Wilt
Journal: JAMA (1992)

<h3>To the Editor.</h3> —We read with interest the article by Johansson et al<sup>1</sup>and the Editorial by Oesterling<sup>2</sup>regarding screening and treatment for prostate cancer. We agree with Johansson et al "that without evidence of benefit from controlled clinical trials, the radical treatment of early-stage prostate cancer remains in its experimental phase." We disagree with the editorial statement by Oesterling that recommends "a serum... PSA concentration<i>and</i>... DRE. If both are normal, the patient should be followed with annual evaluations..." [his italics]. This statement is not convincingly supported by the medical literature or the majority of expert panel recommendations.<sup>3,4</sup>Such an editorial position is of particular concern because an ongoing national prostate cancer screening program, organized and sponsored by a pharmaceutical corporation, also pressures physicians to adopt screening strategies of unproven benefit. The Schering Corporation, manufacturer of flutamide, has sponsored National Prostate Cancer Awareness Week (PCAW) for
Measurement of Na(+)-K+ pump current in isolated rabbit ventricular myocytes using the whole-cell voltage-clamp technique. Inhibition of the pump by oxidant stress.
Authors: M JShattock, HMatsuura
Journal: Circulation Research (1993)

Free radical-induced oxidant stress has been implicated in ischemia and reperfusion-induced injury in the heart. A number of studies have reported that oxidant stress reduces the activity of isolated Na+,K(+)-ATPase enzyme. We have studied the effects of oxidant stress on the Na(+)-K+ pump current recorded in isolated rabbit ventricular myocytes using the whole-cell voltage-clamp technique. Singlet oxygen and superoxide were generated by the photoactivation of rose bengal (50 nM). The compositions of Tyrode's and pipette solutions were designed to block channel currents and electrogenic Na(+)-Ca2+ exchange. Cells were dialyzed with a pipette solution containing 30 mM sodium via wide-tipped (1-2-M omega) electrodes, and outward Na(+)-K+ pump current was recorded during a voltage-ramp protocol. The validity of using such a ramp protocol was confirmed by comparison with steady-state Na(+)-K+ pump current measurements made at the end of 200-msec square-clamp steps. Active currents were abolished by potassium-...
Across-the-papilla side-by-side placement of 6-mm fully covered metallic stents for malignant hilar biliary obstruction: a novel concept that may facilitate reintervention
Authors: Mamoru Takenaka, Tomohiro Yamazaki, Yasuo Otsuka, Kota Takashima, Rei Ishikawa, Masatoshi Kudo
Journal: Endoscopy (2021)

For transpapillary drainage of a malignant hilar biliary obstruction (MHBO) with a metallic stent, considering the risk of branched bile duct obstruction and duodenobiliary reflux, insertion of an uncovered metallic stent above the level of the papilla tends to be selected [1] [2] [3] [4]. However, this form of deployment often makes endoscopic reintervention difficult, even though it is frequently required [5]. Here, we report a novel concept of drainage for MHBO with endoscopic reintervention in mind, in the form of across-the-papilla side-by-side placement of 6-mm fully covered metallic stents.
Subunit-dependent modulation of recombinant L-type calcium channels. Molecular basis for dihydropyridine tissue selectivity.
Authors: AWelling, Y WKwan, EBosse, VFlockerzi, FHofmann, R SKass
Journal: Circulation Research (1993)

At least four calcium channel subtypes (P, T, N, and L) have now been classified on the basis of their biophysical and/or pharmacological properties. L-type channels, a channel family particularly important to physiological function of the cardiovascular system, are identified by their slow voltage- and calcium-dependent inactivation as well as their sensitivity to dihydropyridine (DHP) calcium channel antagonists. In this study, we report the results of experiments in which we have measured the DHP modulation of recombinant calcium channel activity in cells transfected with alpha 1 subunits of cardiac and smooth muscle L-type calcium channels. We find subunit-dependent differences in the voltage and concentration dependence of channel modulation. Our results provide evidence for a molecular basis for DHP sensitivity of heart and smooth muscle calcium channels and, additionally, indicate that, even within one family of calcium channels, slight differences in channel structure can cause marked differences ...
Surgical treatment of ventricular tachycardia after surgical repair of tetralogy of Fallot. Relation between intraoperative mapping and histological findings.
Authors: TMisaki, MTsubota, GWatanabe, YWatanabe, YMatumoto, KIshida, TIwa, ROkada
Journal: Circulation (1994)

BACKGROUNDThe mechanism of ventricular tachycardia (VT) after correction of tetralogy of Fallot (TF) is poorly understood. The purpose of this study was to examine the histopathology of the arrhythmogenic area detected by intraoperative mapping.METHODS AND RESULTSThe patients were three men who underwent radical surgery for TF at age 3, 3, or 5 years, respectively. VT developed at 8, 9, or 11 years, respectively, after surgery, and shock developed during VT in every case. The ECG revealed monomorphic VT in two cases and polymorphic VT in one case. Induction of VT resulted in a wide left-axis deviation-pattern QRS with cycle lengths varying between 260 and 330 milliseconds. The VT origin was identified at the right ventricular outflow tract (RVOT). A radical operation was performed with the patient under cardiopulmonary bypass. On epicardial mapping, delayed activation of the RVOT was recorded during sinus rhythm, and clockwise circus movement of the macroreentry current during VT on the right ventricular ...