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Biomedical subjects

C Delgado

Publications and source records attributed to C Delgado.

At least 109 records · Page 6Linked to original sources
PubMed1985

Electrophysiological effects of platelet-activating factor (PAF-acether) in guinea-pig papillary muscles.

The effects of PAF-acether (10(-11) to 10(-7) M) were studied on the electrical and mechanical activity of guinea-pig papillary muscles. At 10(-11) M PAF-acether did not modify the amplitude and Vmax of the upstroke or the resting membrane potential. At higher concentrations PAF-acether produced a dose-dependent increase in the amplitude and Vmax of the upstroke, shortened the action potential duration and hyperpolarized the resting membrane potential. These effects were accompanied by a biphasic effect on ventricular contractile force. The shortening of the APD was inhibited in muscles pretreated with tetraethylammonium or verapamil. In papillary muscles depolarized by 27 mM K Tyrode solution PAF-acether induced slow action potentials which were blocked by verapamil. PAF-acether produced a dose-dependent increase in amplitude and Vmax of the upstroke on the slow action potentials elicited by isoproterenol, prolonged the action potential duration and hyperpolarized the resting membrane potential. These results suggest that in guinea-pig papillary muscles PAF-acether increased Ca influx via the slow inward current.

Action Potentials↗
PubMed1985

Electrophysiological effects of propafenone in untreated and propafenone-pretreated guinea-pig atrial and ventricular muscle fibres.

The electrophysiological effects of propafenone (10(-7) to 10(-4) M) were studied on guinea-pig isolated atrial and ventricular muscle fibres obtained from untreated animals and animals pretreated with propafenone, 3 and 10 mg kg-1, for 28 days. In untreated atria propafenone produced a dose-dependent decrease in the rate and maximum following frequency, prolonged the sinus node recovery time and reduced the maximum chronotropic responses to isoprenaline. In untreated atrial and ventricular muscle fibres propafenone depressed action potential amplitude and Vmax, reduced the resting membrane potential and prolonged the action potential duration (APD) and the effective refractory period, lengthening the effective refractory period relative to APD. Propafenone depressed the amplitude and Vmax and shortened the duration of the slow action potentials induced by isoprenaline and caffeine in K-depolarized papillary muscles. Pretreatment with propafenone reduced atrial rate, but did not modify the action potential characteristics compared to the values obtained in untreated atria. Further addition of propafenone produced similar but more marked changes in untreated atria. In ventricular muscle fibres pretreated with 3 mg kg-1, action potential characteristics before and after further addition of propafenone were similar to those obtained in untreated fibres. However, muscles pretreated with 10 mg kg-1 exhibited a significant prolongation of the APD compared to that in untreated muscles or those pretreated with 3 mg kg-1; further addition of propafenone shortened the APD even when this parameter was of similar value to those observed in the other two series of experiments. It is concluded that even though the effects of propafenone are similar to those of quinidine (class I antiarrhythmic), it also exhibited class II and class IV actions. In pretreated animals a prolongation of the APD (class III action) could also be involved in the antiarrhythmic effects of the drug.

Animals↗
PubMed1984

Effects of chlorbutol on 45Ca movements and contractile responses of rat aorta and its relevance to the actions of Syntocinon.

The effects of chlorbutol (0.7, 1.4 and 2.8 mM) on the contractile responses induced by KCl and noradrenaline (NA) and on 45Ca movements have been studied on rat isolated thoracic aorta. Chlorbutol decreased, in a dose-dependent manner, contractions induced by KCl and NA and this effect was observed whether it was added before or after the induced contractions. Preincubation with chlorbutol inhibited the contractile responses elicited by addition of Ca (1-5 mM) to Ca-free high-potassium solution. It also inhibited in a dose-dependent manner the 45Ca influx but increased 45Ca efflux in rat aortic strips. These results suggest that chlorbutol decreases peripheral resistance by reducing the availability of intracellular Ca to the contractile machinery in vascular smooth muscle cells. The effects of synthetic oxytocin (Syntocinon) at concentrations containing the same chlorbutol concentration were quantitatively similar from those produced by chlorbutol alone. Therefore, the inhibitory cardiovascular effects ascribed previously to synthetic oxytocin may be attributed to its preservative, chlorbutol, and not to oxytocin itself.

Animals↗
PubMed1984

An analysis of the positive inotropic effect of AR-L 115 BS on isolated rat atria.

The effect of AR-L 115 BS on mechanical and electrical properties of isolated rat atria was investigated. AR-L 115 BS (10(-7) M -5 X 10(-4) M) produced a dose-dependent increase in rate, contractile force and df/dtmax and shortened the sinus node recovery time and the effective refractory period. The increase in contractile force occurred concomitantly with an increase in the height of the plateau of the atrial action potential. The positive inotropic effect produced by AR-L 115 BS depended on the external Ca concentration and was diminished in low Na solution. The drug also decreased the amplitude-interval relationship and post-extrasystolic potentiation. The positive inotropic effect of AR-L 115 BS was inhibited by verapamil and caffeine. These results suggest that in isolated rat atria the positive inotropic effect of AR-L 115 BS might be due to an increase in transmembrane Ca influx into atrial fibres as well as to an effect probably related to the inhibition of Ca sequestration by the sarcoplasmic reticulum.

Animals↗
PubMed1984

Inotropic and electrophysiological effects of PY 108-068 on isolated cardiac preparations.

The inotropic and electrophysiological effects of PY 108-068 (PY), a new Ca-antagonist agent, were studied on isolated atria and guinea-pig papillary muscles. On isolated atria PY produced a dose-dependent decrease in amplitude and rate of spontaneous contractions. This negative inotropic effect was more evident at fast stimulation rates. PY decreased the maximum inotropic and chronotropic responses to isoprenaline and caused a dose-response parallel shift of the Ca dose-response curve. On papillary muscles, PY produced a shortening in action potential duration without changes in the resting potential and the Vmax and amplitude of phase O. PY also produced a dose-dependent decrease in amplitude and Vmax and a shortening of the duration of the slow action potentials elicited by isoprenaline in K (27 mM)-depolarized papillary muscles. These results suggest that in isolated right atria and guinea-pig papillary muscles PY produced a selective inhibition of Ca Influx via the slow inward current.

Action Potentials↗
PubMed1983

Effects of bunaphtine on 45Ca movements in rat aortic smooth muscle.

The effect of bunaphtine (BNA, 5 X 10(-5)M) on La3+ -resistant 45Ca content and 45Ca efflux was studied on rat aortic smooth muscle. BNA decreased both control and norepinephrine-stimulated La3+-resistant 45Ca content and increased the 45Ca efflux. These effects could explain the inhibition of the contractile responses induced by BNA.

Animals↗
PubMed1975

Estrogen binding protein of rat liver.

An estrogen binding protein for estradiol-17beta is present in the liver cytosol of female intact and one day oophorectomized rats. The dissociation constant reveals high affinity binding (Kd: 0.69 +/- 0.14 times 10(-10) M). Quantitation of EBP using a dextran-coated charcoal method shows that this specific macromolecular binding is much less than in the rat uterus, but similar to that in DMBA-induced mammary tumors. Sucrose density gradient analysis shows sedimentation at 8-9 S and 4-5 S when compared to bovine serum albumin.

Animals↗
PubMedDate not supplied

CO(2) wedged hepatic venography: technical considerations and comparison with direct and indirect portography with iodinated contrast.

BACKGROUND: We evaluated the efficacy and safety of CO(2) wedged hepatic venography (CO(2) WHV) by comparing it with direct transjugular (DP) and indirect arterial portography (IP). METHODS: Twenty-one CO(2) WHV and IP examinations were performed in 20 patients; 13 of them also underwent DP within 48 h of CO(2) WHV and IP. IP involved the injection of iodinated contrast into the superior mesenteric and splenic arteries. DP was performed from a transjugular approach, during transjugular intrahepatic portosystem shunt placement, with the injection of iodinated contrast into the superior mesenteric or splenic vein. The parameters evaluated were visualization of vessels and varices, portal vein thrombosis detection, and complications. RESULTS: CO(2) WHV depicted the splenic vein in 57%, the superior mesenteric vein in 62%, the main portal vein in 90%, the right portal vein in 95%, and the left portal vein in 90% of patients. It also demonstrated gastroesophageal varices in seven cases, a splenorenal shunt in one case, mesenteric varices in one case, and a recanalized umbilical vein in one case; other varices were also seen. CONCLUSION: CO(2) WHV is a good and safe technique for demonstrating the portal circulation. It may provide information not obtainable by IP and DP. However, IP provides better demonstration of the variceal network.

Adult↗
PubMedDate not supplied

Ascites due to anastomotic stenosis after liver transplantation using the piggyback technique: treatment with endovascular prosthesis.

Liver transplantation preserving the retrohepatic inferior vena cava, the so-called piggyback technique, is becoming more frequently used because it avoids caval cross-clamping during the anhepatic phase of surgery. However, hepatic venous outflow blockade causing ascites seems to be less infrequent after piggyback than with cavo-caval anastomosis. We report a 62-year-old patient who underwent liver transplantation using the piggyback technique and developed a stenosis in the anastomosis between the hepatic veins and the inferior vena cava leading to severe postoperative ascites. Ascites was unresponsive to diuretic therapy and was associated with renal function impairment. Since the etiology of the stenosis was mechanical (torsion), percutaneous transluminal angioplasty was unsuccessful. Finally, an autoexpandable prosthesis was placed across the anastomosis resulting in rapid and permanent (3 years of follow-up) resolution of ascites.

Anastomosis, Surgical↗
PubMedDate not supplied

Immunogenicity of H-2 positive and H-2 negative clones of a mouse tumour, GR9.

The GR9 tumour was induced with methylcholanthrene in a BALB/c mouse, adapted to tissue culture and cloned without any passage in vivo GR9 clones were typed for H-2 with three monoclonal antibodies that define H-2Kd + Dd, Kd and Dd antigens. A great heterogeneity of H-2d expression was found from clones which were Kd and Dd positive to clones Kd and Dd negative. These results were confirmed for A7 and B9 clones using immunoprecipitation with anti-H-2D.4 and anti-H-2K.31 alloantisera and SDS-PAGE analysis. In addition, the number of chromosomes per cell was heterogeneous amongst the clones, ranging from 38 +/- 2 to pseudotetraploid clones which have 75 +/- 2 chromosomes. GR9 clones were injected into syngeneic BALB/c mice to measure local tumour growth. We found that the growth correlated with the amount of H-2 antigen expressed, i.e. clones with low H-2d expression were highly malignant while clones with normal H-2d expression were highly immunogenic. Finally we found that BALB/c mice immunized against A7 (Kd, Dd-positive) protected against A7, as expected, but surprisingly also against B9 (Kd, Dd-negative).

Animals↗
PubMedDate not supplied

Characterization of the syngeneic anti-tumour response against the GR9 tumour with the production of isoantisera and monoclonal antibodies.

Isoantisera and syngeneic monoclonal antibodies have been produced against A7, a clone derived from a BALB/c methylcholanthrene-induced tumour named GR9. The antigens defined by the isoantisera and mAbs are widely distributed in a large number of GR9 clones as well as in other tumour cell lines of different aetiology and origin. Two GR9 clones with marked differences in H-2 expression and syngeneic in vivo growth (A7, which is H-2d-positive and highly immunogenic and B-9, which is H-2d-negative and highly malignant) were selected to further analyse the presence or absence of the antigens recognized by the syngeneic anti-tumour antibodies. Immunoprecipitation data with two different isoantisera revealed a group of proteins with a molecular weight of Mr 65-70,000 present in both clones. Furthermore, immunoprecipitation with the A7-1 mAb again showed a single Mr 65K band present in A7 and B9 clones. We conclude that the marked differences observed in the syngeneic growth of the two clones are not due to differences in tumour associated antigens (TAA), defined by syngeneic antibodies, and emphasize the role that class I H-2 antigens could play in tumour rejection.

Animals↗
PubMedDate not supplied

Successful lipid-complexed amphotericin B treatment of Candida arthritis in a lymphoma patient.

Fungal arthritis is uncommon but has been increasingly diagnosed over recent years, particularly in patients with immunodeficiency due for instance to hematological malignancies. Candida albicans is the most frequent causative agent, and the knee is the joint most often involved. Amphotericin B is the drug of choice, but is associated with significant toxicity. Recently developed lipid formulations of amphotericin B have been found as effective and less toxic than the conventional formulation. We report a new case of Candida arthritis that occurred after chemotherapy for nonHodgkin's lymphoma and was successfully treated with lipid-complexed amphotericin B.

Aged↗
PubMedDate not supplied

Effects of pimobendan and UD-CG-212 CL on calcium exchange and contraction in isolated rabbit aorta.

The effects of pimobendan and its O-demethylmetabolite UD-CG-212 CL on contractile responses and transmembrane Ca fluxes were studied on rabbit isolated aortic rings. Both pimobendan and UD-CG-212 CL (10(-7) M-5 X 10(-4) M) concentration-dependently inhibited the contractile responses induced by KCl (80 mM) and noradrenaline (10(-6) M). This inhibitory effect was observed when these compounds were added either before or after the induced contractions, but was reduced in aortic rings after removal of endothelium. Pimobendan and UD-CG-212 CL shifted the concentration-response curve to noradrenaline downwards and to the right and inhibited the contractile responses elicited by addition of Ca (1-5 mM) to Ca-free high K solution. Pimobendan also inhibited the contractile responses induced by caffeine (20 mM) in aortic rings incubated in normal or in Ca-free medium. At 5 X 10(-4) M, pimobendan inhibited 45Ca influx in resting as well as in aortic rings stimulated by high K and noradrenaline and increased the rate of 45Ca efflux in nonstimulated aortae. It is concluded that pimobendan and its O-dimethylmetabolite UD-CG-212 CL exhibit vasodilator properties in the isolated rabbit aorta by their acting at multiple sites of action, thus decreasing the availability of Ca required for smooth muscle activation.

Animals↗