tbuckley/cabot-search huggingface dataset:
Multiple types of Ca2+ currents in single canine Purkinje cells.
Authors: G NTseng, P ABoyden
Journal: Circulation Research (1989)

Whole-cell Ca2+ channel currents were recorded from isolated single canine Purkinje and ventricular cells to determine whether there were multiple types of Ca2+ channels in these two cell types, as in many other excitable tissues. The experimental conditions were such that currents other than Ca2+ channel currents were largely suppressed. The charge carrier was either Ca2+ or Ba2+ (5mM). In every canine Purkinje cell studied (n = 36), we saw T and L Ca2+ channel currents that are similar to their counterparts in other tissues. Neither current was affected by tetrodotoxin (30 microM), but both were reduced by Mn2+ (5mM). Ni2+ (50 microM) blocked T more than L current. Nisoldipine (1 microM) apparently abolished the L current but also decreased the T current by 50%. Substitution of Ba2+ for Ca2+ augmented and prolonged L current but did not affect T current significantly. At 36 degrees C and with 5 mM [Ca2+]o, T current inactivated over a voltage range from -70 to -30 mV whereas L current inactivated betwee...
Pituitary suppression in chronic airways disease?
Authors: D Newton, I Bone, S M Barrow, P Sheridan
Journal: BMJ (1979)

cases of travellers' diarrhoea belonged to sero- groups previously associated with infantile gastroenteritis.Indeed, one of our toxigenic strains could not be typed at all.Therefore in screening for ETEC in travellers with diarrhoea not associated with Salmonella and Shigella we feel that it is important to underline the need to test several colonies of E coli isolated from the primary culture, regardless of serotype.
Antiarrhythmic effects of potassium channel openers in rhythm abnormalities related to delayed repolarization.
Authors: LCarlsson, CAbrahamsson, LDrews, GDuker
Journal: Circulation (1992)

BACKGROUNDEarlier observations have indicated that repolarization-delaying agents may, under certain circumstances, have the propensity to induce polymorphous ventricular tachyarrhythmias (PVTs) (i.e., torsade de pointes). We have studied whether the potassium channel opener pinacidil and two of its pyridylcyanoguanidine analogues (P1075 and P1188) have any antiarrhythmic effects on clofilium-induced PVTs and triggered responses in rabbits in vivo and in vitro.METHODS AND RESULTSAnesthetized rabbits were pretreated with propranolol (2 mumol/kg i.v.) and subsequently given a concomitant intravenous infusion of clofilium (63 nmol/kg/min for maximally 15 minutes) and the alpha 1-agonist methoxamine (70 nmol/kg/min). In vehicle-pretreated rabbits (n = 19), clofilium invariably induced PVTs, which closely resembled torsade de pointes and were preceded by a marked prolongation of the QTU interval (27 +/- 2.4%, p less than 0.001). In a separate group of seven rabbits in which monophasic action potentials were re...
Contractility and stiffness of noninfarcted myocardium after coronary ligation in rats. Effects of chronic angiotensin converting enzyme inhibition.
Authors: S ELitwin, C MLitwin, T ERaya, A LWarner, SGoldman
Journal: Circulation (1991)

BACKGROUNDPrevious studies have shown that global left ventricular function is depressed after myocardial infarction. However, little is known about the effects of myocardial infarction on contractility and the passive-elastic properties of residual myocardium.METHODS AND RESULTSWe evaluated isometric function and passive myocardial stiffness in isolated, noninfarcted left ventricular papillary muscle from rats 6 weeks after sham operation or myocardial infarction. Maximal developed tension and peak rate of tension rise (+dT/dt) were significantly decreased in untreated rats with large myocardial infarction compared with controls (3.3 +/- 1.1 versus 4.3 +/- 0.6 g/mm2 and 49.5 +/- 17.5 versus 72.5 +/- 10.5 g/mm2/sec, respectively). Time to peak tension was prolonged (120 +/- 8 versus 102 +/- 4 msec) and myocardial stiffness was increased in untreated myocardial infarction rats compared with controls (35.2 +/- 4.9 versus 24.2 +/- 3.7). Rats with smaller myocardial infarctions differed from controls only wit...
Regulation of cell locomotion by nanosecond-laser-induced hydroxyapatite patterning
Authors: Seung-Hoon Um, Jaehong Lee, In-Seok Song, Myoung-Ryul Ok, Yu-Chan Kim, Hyung-Seop Han, Sang-Hoon Rhee, Hojeong Jeon
Journal: Bioactive Materials (2021)

Hydroxyapatite, an essential mineral in human bones composed mainly of calcium and phosphorus, is widely used to coat bone graft and implant surfaces for enhanced biocompatibility and bone formation. For a strong implant–bone bond, the bone-forming cells must not only adhere to the implant surface but also move to the surface requiring bone formation. However, strong adhesion tends to inhibit cell migration on the surface of hydroxyapatite. Herein, a cell migration highway pattern that can promote cell migration was prepared using a nanosecond laser on hydroxyapatite coating. The developed surface promoted bone-forming cell movement compared with the unpatterned hydroxyapatite surface, and the cell adhesion and movement speed could be controlled by adjusting the pattern width. Live-cell microscopy, cell tracking, and serum protein analysis revealed the fundamental principle of this phenomenon. These findings are applicable to hydroxyapatite-coated biomaterials and can be implemented easily by laser patterning without complicated processes. The cell migration highway can promote and control cell movement while maintaining the existing advantages of hydroxyapatite coatings. Furthermore, it can be applied to the surface treatment of not only implant materials directly bonded to bone but also various implanted biomaterials implanted that require cell movement control.
Sites of action and active forms of lidocaine and some derivatives on cardiac Purkinje fibers.
Authors: J IGliklich, B FHoffman
Journal: Circulation Research (1978)

We have compared the effects of lidocaine (L) to those of several derivatives in an attempt to determine the sites of action and active forms of the molecules. We studied cardiac Purkinje fibers with intracellular microelectrodes, and drugs were administered by superfusion or by iontophoretic intracellular injection. We compared to L the effects of QX-314 and QX-572, two quaternary derivatives, and also compound 6603, a tertiary analogue with a pKa of 9.81. When administered by superfusion in concentrations of 10(-5) and 10(-4) M, all four agents exerted qualitatively similar effects on the transmembrane action potential. The rate of onset of action of the quaternary derivatives was considerably slower than that of L and their actions were not reversed by superfusion for 1 hour with drug-free solution. Comparison of effects of L and QX-314 after intracellular injection showed that attenuation of Vmax, and thus of the fast inward current, results from interaction of the charged form acting form acting from...
ATP-sensitive K+ channels mediate dilatation of cerebral arterioles during hypoxia.
Authors: HTaguchi, D DHeistad, TKitazono, F MFaraci
Journal: Circulation Research (1994)

We tested the hypothesis that dilatation of cerebral arterioles during hypoxia is mediated by activation of ATP-sensitive K+ channels. The diameter of pial arterioles was measured through a closed cranial window in anesthetized rabbits. Topical application of aprikalim (10(-6) mol/L), a direct activator of ATP-sensitive K+ channels, dilated pial arterioles by 18 +/- 3% (mean +/- SEM). Glibenclamide (10(-6) mol/L), an inhibitor of ATP-sensitive K+ channels, virtually abolished aprikalim-induced vasodilatation. When arterial PO2 was reduced from 129 +/- 3 to 25 +/- 1 mm Hg, the diameter of cerebral arterioles increased by 66 +/- 9% (P < .05). Glibenclamide inhibited dilatation of pial arterioles during hypoxia by 46 +/- 5% (P < .05). In contrast, vasodilatation in response to sodium nitroprusside was not altered by glibenclamide. Topical application of adenosine (10(-4) mol/L) increased arteriolar diameter by 21 +/- 4%. Glibenclamide did not affect adenosine-induced vasodilatation. These findings suggest th...
Premature pulmonary valve opening.
Authors: L SWann, A EWeyman, J CDillon, HFeigenbaum
Journal: Circulation (1977)

Premature opening of the pulmonary valve (opening independent of atrial or ventricular systole) was originally described in a case of sinus of Valsalva rupture into the right atrium. Since that time we have observed five additional cases in which the pulmonary valve opened prematurely. Entities encountered included: 1) constrictive pericarditis; 2) Loeffler's endocarditis; 3) Ebstein's anomaly with tricuspid regurgitation; 4) tricuspid regurgitation following tricuspid valvulectomy, and 5) pulmonary regurgitation accompanied by atrial septal defect. In the first two cases, premature pulmonary valve opening is felt to be due to restriction of diastolic filling of the right ventricle with subsequent early diastolic rise in pressure equalling or exceeding pulmonary artery diastolic pressure. In the latter three cases, the increased volume of blood entering the right ventricle again appeared to result in a rapid rise in initial right ventricular diastolic pressure and to produce premature opening of the pulmo...
Role of heart and lung receptors with nonmedullated vagal afferents in circulatory control.
Authors: P NThorén, D EDonald, J TShepherd
Journal: Circulation Research (1976)

Vagal afferents from the cardiopulmonary region exert a tonic inhibition on the vasomotor center. This is demonstrated by constriction of systemic resistance and splanchnic capacitance vessels and by increased output of renin when the vagi are cut or blocked. In dogs, removal or selective denervation of organs showed that receptors in the lungs, the atria, and the ventricles each are responsible for the vasomotor inhibition. That this inhibition is due to nonmedullated vagal afferents (C fibers) was demonstrated by selective cooling of the vagi, anodal block of medullated afferents, and selective electrical stimulation of medullated and nonmedullated fibers. In the open-chest cat the discharge frequency of individual C fibers is sparse and irregular (mean, 1.4 impulses/sec) but increases to 10 or more impulses/sec with moderate increases in cardiac filling pressure and exhibits cardiac rhythmicity or is continuous throughout the cardiac cycle. The inhibition of sympathetic vasomotor outflow effected throu...
Oral administration of DuP 753, a specific angiotensin II receptor antagonist, to normal male volunteers. Inhibition of pressor response to exogenous angiotensin I and II.
Authors: YChristen, BWaeber, JNussberger, MPorchet, R MBorland, R JLee, KMaggon, LShum, P BTimmermans, H RBrunner
Journal: Circulation (1991)

BACKGROUNDThe purpose of the present study was to assess the inhibitory effect of DuP 753, an orally active angiotensin II receptor antagonist, on the pressor action of exogenous angiotensin I and II in healthy male volunteers.METHODS AND RESULTSIn the first study (single-dose study), eight volunteers were included in a 2-day protocol repeated four times at 1-week intervals. In each phase, a different dose of drug (2.5, 5, 10, 20, or 40 mg) or placebo was given. The peak systolic blood pressure response to a test-dose of angiotensin I was determined serially before and after oral administration of DuP 753 by continuously monitoring finger blood pressure using a photoplethysmographic method. DuP 753 reduced the systolic blood pressure response to angiotensin I in a dose-dependent fashion. Three, 6, and 13 hours after the 40-mg dose, blood pressure response decreased to 31 +/- 5%, 37 +/- 6%, and 45 +/- 3% of the control values (mean +/- SEM, n = 7), respectively. In the second study, 29 volunteers were trea...
Dispatcher-assisted cardiopulmonary resuscitation. Validation of efficacy.
Authors: A LKellermann, B BHackman, GSomes
Journal: Circulation (1989)

Dispatcher-delivered telephone instruction in cardiopulmonary resuscitation (CPR) has been proposed to increase rates of bystander CPR in cases of out-of-hospital cardiac arrest. We tested the efficacy of a previously developed CPR message using a recording mannikin in a high stress, simulated cardiac arrest scenario. Community volunteers were unaware they would perform CPR until immediately before each trial. Performance of volunteers without prior CPR training (group A, n = 65) who received telephone instruction was compared with that of previously trained volunteers (group B, n = 43) who received the same message. Performances of both groups were also compared with a third group (group C, n = 43) composed of previously trained volunteers who did not receive the message. Quality of CPR was graded by three CPR instructors using explicit criteria. Printout strips from the recording mannikins were also analyzed. Evaluators were unaware of the training status of volunteers. The three groups were of comparab...
Altered myocardial perfusion in patients with angina pectoris or silent ischemia during exercise as assessed by quantitative thallium-201 single-photon emission computed tomography.
Authors: J JMahmarian, C MPratt, M KCocanougher, M SVerani
Journal: Circulation (1990)

The extent of abnormally perfused myocardium was compared in patients with and without chest pain during treadmill exercise from a large, relatively low-risk consecutive patient population (n = 356) referred for quantitative thallium-201 single-photon emission computed tomography (SPECT). All patients had concurrent coronary angiography. Patients were excluded if they had prior coronary angioplasty or bypass surgery. Tomographic images were assessed visually and from computer-generated polar maps. Chest pain during exercise was as frequent in patients with normal coronary arteries (12%) as in those with significant (greater than 50% stenosis) coronary artery disease (CAD) (14%). In the 219 patients with significant CAD, silent ischemia was fivefold more common than symptomatic ischemia (83% versus 17%, p = 0.0001). However, there were no differences in the extent, severity, or distribution of coronary stenoses in patients with silent or symptomatic ischemia. Our major observation was that the extent of qu...
Money and medicine.
Authors: R Klein
Journal: BMJ (1979)

The unnerving discovery every Minister of Health makes at or near the outset of his term of office is that the only subject he is ever destined to discuss with the medical profession is money."So wrote Mr Enoch Powell in 1966, reflecting on his period in office.'If the medical profession's disappointed reactions to the latest Review Body report2 are anything to go by, Mr Patrick Jenkin may soon be tempted to echo these remarks.Like all his predecessors, the new Secretary of State is likely to find himself embroiled in a never-ending argument with the medical profession about the appropriate level of pay.Clearly no new forms of contract, providing for different methods of payment, can end the argument about the level of rewards.So long as the National Health Service is centrally financed, governments-whether Conservative or Labour-are going to insist on controlling the total wage bill and are likely to resist any move which would give the profession an open-ended cheque to determine its own earnings.Interestingly, the Review Body largely accepted the Government's view that the new consultant contract should be financed out of existing funds, though it did propose an 8% once-and-for-all increase to cover the transitional costs of change.Not unexpectedly, perhaps, con- sultants' representatives have rejected the pricing of the new contract.
Reactive oxygen metabolites relax the lamb ductus arteriosus by stimulating prostaglandin production.
Authors: R IClyman, O DSaugstad, FMauray
Journal: Circulation Research (1989)

To determine whether oxygen metabolites can cause ductus relaxation, we used rings of fetal ductus obtained from 36 near-term lambs and measured the effects of the oxygen metabolites generated by the combination of hypoxanthine and xanthine oxidase. The oxygen metabolites produced by hypoxanthine plus xanthine oxidase caused relaxation of the ductus that was inhibited by catalase (hydrogen peroxide scavenger) but not by superoxide dismutase (superoxide anion scavenger). In addition, hypoxanthine plus xanthine oxidase produced a 14-fold increase in prostaglandin (PG) E2 production with only twofold increase in 6-keto-PGF1 alpha (the stable metabolite of PGI2). PGE2 is the most potent relaxant of the ductus arteriosus. The presence of either catalase or indomethacin blocked both the increase in prostaglandin production and the relaxation. We conclude that reactive oxygen metabolites relax the ductus arteriosus and oppose the normal constriction that occurs after birth. However, the vasoactive effects of rea...
Results and follow-up after percutaneous pulsed laser-assisted balloon angioplasty guided by spectroscopy.
Authors: H JGeschwind, EAptecar, GBoussignac, J LDubois-Randé, RZelinsky, GPoirot, TTomaru
Journal: Circulation (1991)

BACKGROUNDFew data are available on the long-term outcome of patients who undergo laser-assisted balloon angioplasty for recanalization of occluded peripheral arteries. Because the cost of laser angioplasty is high, the value of the method should be carefully analyzed before it can be considered a routine method for recanalization. The purpose of this study was to evaluate the early and late results of laser-assisted balloon angioplasty in patients who could not be recanalized by conventional techniques.METHODS AND RESULTSLaser angioplasty was performed in 66 patients with total occlusion of the iliofemoral artery in whom mechanical techniques failed to recanalize the obstructed vessel. The system consisted of a pulsed dye laser operated at 480 nm, 2 microseconds/pulse, 5 Hz, 50 mJ/pulse coupled into a 0.021-in. laser catheter. The treatment laser was connected with a diagnostic laser to induce tissue fluorescence for spectroscopic analysis via the same fiber. The treatment laser was emitted only when ath...
cis-regulatory elements and trans-acting factors directing basal and cAMP-stimulated human renin gene expression in chorionic cells.
Authors: PBorensztein, SGermain, SFuchs, JPhilippe, PCorvol, FPinet
Journal: Circulation Research (1994)

Much knowledge was accumulated in the regulation of plasma renin activity and renin secretion during recent years. However, the mechanisms of renin gene transcription, especially for the human gene, have been poorly studied because of the lack of cell lines expressing renin. Cells derived from chorion tissue were used to study renin gene transcription because these cells express renin and regulate renin secretion in a similar way to JG cells. The present study was performed to determine the cis-regulatory elements and the trans-acting factors involved in human renin gene expression using chorionic cells. Transient DNA transfections were performed with various constructs containing the 5'-flanking region of the human renin gene. 5'-Deletion analysis of the human renin promoter (from -2616 to -67 bp) revealed the presence of two proximal negative cis-regulatory elements between -374 and -273 bp and between -273 and -137 bp. These elements were not present in a non-renin-producing cell line, JEG-3 cells. DNa...
Aortic sinus of Valsalva aneurysms simulating primary right-sided valvular heart disease.
Authors: B HBulkley, G MHutchins, R SRoss
Journal: Circulation (1975)

While acute regurgitation is the most common valvular lesion associated with aortic sinus of Valsalva aneurysms, this report describes the pathological findings in five patients in whom primary right-sided valve dysfunction was simulated by sinus of Valsalva aneurysms. In two patients aneurysms of the noncoronary sinus projected into the right atrium at the level of the tricuspid valve and caused tricuspid incomptence. In three patients aneurysms of the right sinus of Valsalva projected into the right ventricle immediately below the pulmonic valve and caused pulmonary outflow tract obstruction. In only one of these patients was the aneurysm perforated at necropsy. Although valvular dysfunction was evident clinically, in none was there a clinical suspicion of a sinus of Valsalva aneurysm. In addition to valvular dysfunction, two patients had conduction disturbances and two, right coronary arterial occlusions found to be the result of aneurysms. The risks of valve dysfunction, arrythmias, aneurysm rupture, ...
Influence of mitral valve morphology on double-balloon catheter balloon valvuloplasty in patients with mitral stenosis. Analysis of factors predicting immediate and 3-month results.
Authors: C LReid, P AChandraratna, D TKawanishi, AKotlewski, S HRahimtoola
Journal: Circulation (1989)

To determine if mitral valve morphology influences the results of double-balloon catheter balloon valvuloplasty (CBV) for mitral stenosis, two-dimensional echocardiography was performed in 33 patients before CBV. The two-dimensional echocardiographic features of leaflet motion, leaflet thickness, subvalvular disease, and commissural calcium and 14 pre-CBV clinical and hemodynamic variables were then correlated to the immediately post-CBV mitral valve area (MVA). At 3 months after CBV, the two-dimensional echocardiographic features of patients with a 25% or greater decrease in MVA were analyzed to determine whether mitral valve morphology had influenced early results. Leaflet motion had a significant relation with the immediately post-CBV MVA (r = 0.67, y = 4.5x + 0.29, and SEE = 0.45). Leaflet thickness had a weak and negative relation (r = -0.48, y = -0.17x + 2.6, and SEE = 0.53) with the immediately post-CBV MVA. Subvalvular disease and commissural calcium had no significant relation to the immediately ...
Serum lipoprotein profile in children from a biracial community: the Bogalusa Heart Study.
Authors: S RSrinivasan, R RFrerichs, L SWebber, G SBerenson
Journal: Circulation (1976)

Serum lipoprotein profiles in 3182 children, ages 5-14 years, were studied in a biracial community as part of the Bogalusa Heart Study to describe the early natural history of atherosclerosis. White and black children showed similar mean levels of beta-lipoproteins. Pre-beta-lipoprotein levels, however, were significantly higher in white shildren, while significantly higher levels of alpha-lipoprotein were found in black children. Girls had generally higher levels of beta- and pre-beta-lipoprotein and lower levels of alpha-lipoprotein than boys, although the differences were not significant at each age group. With age there was little change in alpha-lipoprotein levels, a significant increase in pre-beta-lipoprotein levels and a slight but significant decrease between 11 and 14 years in beta-lipoprotein levels. The correlation of alpha-lipoprotein was negative with beta-lipoprotein and, to a greater extent, with pre-beta-lipoprotein. The above inverse relationships were significantly greater in white chil...