PubMed Health⌕ Search

Biomedical subjects

C Valenzuela

Publications and source records attributed to C Valenzuela.

At least 91 records · Page 5Linked to original sources
PubMed1988

[Experimental esophageal transsection. Application to the treatment of hemorrhage in portal hypertension].

Nineteen of twenty dogs undergoing experimental esophageal transection with mechanical suturing were followed up over 1 to 120 days by means of light and electron microscopy examinations to evaluate changes in suture line. Histology showed few reactions to the metallic clips, the absence of new vessel formation with early healing from the 4th day, development of collagen fascicles after 1 week and consolidation after 2 weeks with reparation by the end of 1st month. Stability of healing process was apparent between 3 and 4 months, without evidence of stenosis due to scar tissue.

Animals↗
PubMed1988

Intraarticular progesterone: effects of a local treatment for rheumatoid arthritis.

The antiinflammatory effect of a single intraarticular injection of progesterone was investigated in 12 patients with rheumatoid arthritis. A local, but no systemic decline of inflammation was observed in 10 of them for at least one month. The average local scores of inflammation at Days 7, 14, 21 and 30 after injection were significantly lower than pretreatment scores (p less than 0.000003 for each comparison). In some patients the effect continued for up to 2 months. No important side effects were observed during the following 2 months. However, a more prolonged followup of treated patients is necessary to rule out the late onset of side effects.

Arthritis, Rheumatoid↗
PubMed1987

Electrophysiological effects of 5-hydroxypropafenone on guinea pig ventricular muscle fibers.

The effects of 5-hydroxypropafenone (5-OH-P), the main metabolite of propafenone, were studied in guinea pig papillary muscles obtained from untreated animals and from animals pretreated with 5-OH-P, 3 mg/kg for 24 days. In untreated muscles perfused with 2.7 and 5.4 mM K+, 5-OH-P depressed action potential amplitude and Vmax, reduced the resting membrane potential, and prolonged the effective refractory period (ERP), but had no effect on the duration of the action potential (APD), recovery time (RT), or ERP/RT ratio. 5-OH-P also shifted the membrane responsiveness curve downward and to the left (i.e., in hyperpolarizing direction), prolonged the ERP/APD ratio, depressed the amplitude and Vmax, and shortened the duration of the slow action potentials induced by isoproterenol in K+-depolarized muscles. Pretreatment with 5-OH-P had no effect on phase 0 characteristics or resting membrane potential, but it shortened the APD, ERP, and RT and decreased the ERP/APD ratio. Further addition of 5-OH-P produced similar but more marked changes than in untreated muscles. In papillary muscles perfused with 10 mM K+, the depressant effects of 5-OH-P on phase 0 characteristics and ERP/APD ratio were potentiated. A slight lengthening of the APD was also observed. Because all these effects are similar to those previously described with propafenone, it is concluded that 5-OH-P is an active metabolite which exhibits class 1 antiarrhythmic effects and which may be responsible for some of the cardiodepressant and antiarrhythmic effects previously described for propafenone.

Action Potentials↗
PubMed1987

Effects of 5-hydroxy-propafenone in guinea-pig atrial fibres.

The effects of 5-hydroxy-propafenone (5-OH-P), an active metabolite of propafenone, were studied on isolated atrial muscle fibres obtained from non-treated guinea-pigs and from animals pretreated with 5-OH-P, 3 mg kg-1, for 28 days. In untreated atria 5-OH-P, 10(-8) M-10(-4) M, produced a dose-dependent decrease in amplitude and df/dtmax and reduced the amplitude of the slow contractions induced by isoprenaline and histamine in high K+ media. 5-OH-P also produced a dose-dependent decrease in atrial rate, prolonged the sinus node recovery time and reduced the maximum chronotropic responses to isoprenaline. In untreated atrial muscle fibres 5-OH-P depressed action potential amplitude and Vmax, reduced the resting membrane potential and prolonged the action potential duration (ADP) and the effective refractory period, lengthening the effective refractory period relative to APD. Pretreatment with 5-OH-P reduced atrial rate and increased contractile force, but did not modify the action potential characteristics from the values obtained in untreated atria. Further addition of 5-OH-P produced similar but more marked changes than in untreated atria. It is concluded that in guinea-pig isolated atrial muscle fibres 5-OH-P, like propafenone, exhibits class I (membrane stabilizing), class II (antisympathetic) and class IV (Ca antagonistic) antiarrhythmic actions. Therefore, this metabolite could be responsible, at least in part, for some of the antiarrhythmic effects previously attributed to propafenone.

Adrenergic beta-Antagonists↗
PubMed1987

Comparative effects of oxodipine and nifedipine in the isolated guinea-pig heart.

The electromechanical effects of 2 dihydropyridines, oxodipine (OXD) and nifedipine, were compared on isolated guinea-pig atrial and ventricular muscle fibres. Intracardiac conduction times were measured in the Langendorff-perfused guinea-pig heart. On isolated atria OXD and nifedipine produced a dose-dependent decrease in rate and amplitude of contractions, the negative inotropic effect being accompanied by a shortening of the time to peak tension and time for total contraction. In both atrial and ventricular muscle fibres OXD and nifedipine shortened the duration of the action potential without altering the resting membrane potential and the Vmax and amplitude of phase 0. OXD also decreased the amplitude and Vmax and shortened the duration of the slow action potentials and decreased the amplitude of the slow contractions elicited by isoprenaline in K-depolarized papillary muscle fibres. In the Langendorff-perfused heart OXD and nifedipine slowed the conduction through the A-V node at concentrations at which it had no effect on intraatrial and intraventricular conduction times. The depression on A-V conduction was more marked with nifedipine than with OXD. All these results indicate that in the guinea-pig heart OXD, a new dihydropyridine, exhibit a potent and selective inhibition of Ca influx via the slow inward current.

Action Potentials↗
PubMed1986

Electrophysiological effects of amoxapine in untreated and in amoxapine-pretreated rat atria.

The effects of amoxapine (10(-7)-10(-4) M) have been studied in rat atrial fibres obtained from untreated animals and animals pretreated for 28 days with amoxapine (10 mg kg-1, i.p.). In untreated atria amoxapine reduced atrial rate, contractile force and df/dtmax, prolonged the sinus node recovery time and decreased atrial excitability. Amoxapine also decreased amplitude and Vmax of the upstroke, prolonged the duration of the action potential (APD) and effective refractory period (ERP) and reduced the resting membrane potential. During the treatment with amoxapine behavioural and cardiovascular adverse effects, including hypotension, tachycardia and prolongation of the Q-Tc, were observed. However, with the exception of the ERP which was significantly prolonged in pretreated atria, pretreatment with amoxapine did not modify the control values of the measured parameters compared to those obtained in untreated atria. Further addition of amoxapine produced similar changes in both pretreated and untreated atria. However, in contrast to untreated atria, in pretreated atria the prolongation of the ERP produced by amoxapine exceeded the prolongation of the APD and thus, the ERP/APD ratio increased. The decrease in atrial excitability was also more marked in pretreated than in untreated atria. Amoxapine inhibited the slow action potentials and contractions induced by isoprenaline in K-depolarized atria. It is concluded that the electrophysiological effects of amoxapine on rat atrial fibres are similar to those described for other tricyclic antidepressants. Possible explanations for the lower cardiodepressant activity of amoxapine are discussed.

Action Potentials↗
PubMed1985

Negative inotropic effect of somatostatin in guinea-pig atrial fibres.

The effect of somatostatin (SS, 1 X 10(-7) M-5 X 10(-6) M) was studied on the electrical and mechanical properties of isolated atria of the guinea-pig. On spontaneously beating right atria, SS produced a dose-dependent negative inotropic effect which was accompanied by a decrease in atrial rate and a prolongation of the sinus node recovery time. In electrically driven left atria, SS produced a dose-dependent negative inotropic effect which occurred concomitantly with a decrease in the amplitude and duration of the plateau phase of the action potential of atrial fibres. SS also decreased the amplitude and maximum rate of depolarization of the slow action potential as well as the amplitude of the slow contractions induced by isoprenaline and caffeine in K-depolarized atrial fibres. The negative inotropic effect of SS varied with the concentration of Ca and Na in the bathing media and the frequency of stimulation. SS, 1 X 10(-6) M and 5 X 10(-6) M, decreased 45Ca uptake in electrically driven atria. All these results suggest that the negative inotropic effect produced by SS on rat isolated atria is related to its ability to reduce Ca influx via the slow inward Ca current.

Action Potentials↗
PubMed1979

Trichuriasis. Roentgenographic features and differential diagnosis with lymphoid hyperplasia.

Twenty patients with massive trichuriasis were studied with double contrast barium enema. The following changes were observed: 1) Impregnation defects of the colonic wall probably due to abundant mucous secretions. 2) Granular features. 3) Pear-shaped caecum. 4) Radiolucid ringlike images with some contrast material in its center, similar to those seen in lymphoid hyperplasia. On closer observation it was seen that the radiolucid ring was not complete and was continued by a prolongation which corresponds to the whipworm. This feature is central to the differential diagnosis.

Cecum↗
PubMedDate not supplied

[Clinical features of multiple sclerosis in Western Cuba. A comparison with two other regions in the country].

INTRODUCTION: Multiple sclerosis (MS) is an inflammatory disease in its early stages whose primary or secondary immunological mechanisms produce reversible or irreversible lesions in the myelin and axons in the central nervous system. The first case of MS in Cuba was reported in 1965. Current prevalence of MS is considered to be 10 cases/100,000 inhabitants. AIMS: The aim of this study was to characterise MS in Western Cuba from a clinical point of view and in comparison with other similar studies carried out in two other regions in the country. PATIENTS AND METHODS: 50 patients living in the western region were clinically assessed. Statistical tests were carried out to compare this survey with two similar studies conducted in the central and eastern regions. RESULTS: 80% of our patients were females, predominantly white skinned, the main events in their family histories were neurological diseases and psychiatric diseases, essentially schizophrenia, the chief triggering event being psychic tension, the most frequent form of progression was the remittent recurring form, followed by secondary progressive form, and then the primary progressive; the main symptoms at onset were visual, followed by pyramidal and sensory; the most strongly affected functional system was the pyramidal and then the sensory system; the functional systems are more affected in the primary progressive form, except the visual and the brainstem; the largest group of patients corresponded to those that had a history of over 10 years with the disorder. By far the majority of results compared with the series from the central region and from Santiago de Cuba were similar, but some significant differences did appear on comparing these two series. CONCLUSIONS: The study shows the characteristics of the disease in the Western region valuated using distinct parameters and several differences between the three series can be observed fundamentally with regard to skin colour, triggering events, symptoms at onset and functional involvement in the forms of progression.

Cuba↗