Search PubMed⌕ Search

Biomedical subjects

L Romero

Publications and source records attributed to L Romero.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Influence of the permeability of the artery responsible for the infarction on the variability of heart rate and late potentials. Its importance in the risk stratification after myocardial infarction].

The use of the heart rate variability for the study of the Autonomic nervous system has been well established. We analyzed late potentials and heart rate variability in 29 control patients and in 102 consecutive patients with a first myocardial infarction. The data obtained were analyzed with both, the medical treatment (thrombolysis and beta-blockers) and the patency of the infarct related vessel. Patients with an infarct had diminished vagal tone as compared with the control group. Those patients with occluded related arteries showed higher incidence of late potentials; interestingly patients with late potentials also had diminished vagal tone. Without looking at the patency of the infarct related artery, thrombolitic and betablocker therapy did not have any effect on vagal tone. All the variables were correlated with the patency of the infarct related artery. Those patients with patent arteries had a preservation of the vagal tone; this was independent of the treatment received and the presence of late potentials. We concluded that the patency of the infarct related artery determines the absence of late potentials and preservation of the vagal tone. This might be one of the mechanisms of how thrombolitic therapy decreases the incidence of cardiac death.

Action Potentials↗
PubMed1992

Effects of a high molecular weight toxin from the sea anemone Condylactis gigantea on cholinergic responses.

1. The effects of a high molecular weight toxin isolated from the sea anemone Condylactis gigantea (Condytoxina 2) on the cholinergic responses were studied in two different preparations: identified cells of a land snail and enzymatically dissociated mice sensory neurons. These neurons were studied using intracellular recording and concentration clamp techniques respectively. 2. The toxin produces a concentration-dependent dual effect on the cholinergic responses in both preparations. Thus the application of the toxin at concentrations up to 25 nmol/l produces a reversible block of the response whereas higher doses potentiates it. 3. These results suggest that Condytoxina 2 contains an active compound(s) with the capacity to bind to the nicotinic acetylcholine receptor of excitable cells in both snail and mice neurons. During this action complex allosteric interactions among the binding sites could occur.

Animals↗
PubMed1988

Evaluating hyperfiltration with glycine in hypertensive rats with renal ablation.

Hypertension-induced renal damage is mediated by increased glomerular pressure and flow. These alterations have been evaluated by the renal response to protein or amino acids. To test this assumption, we studied glomerular hemodynamic responses to glycine infusion in rats with reduced renal mass, with and without Goldblatt hypertension. The left kidney was ablated by two thirds in 12 rats, and in 5, hypertension was induced by clipping the right renal artery. Seven normal, unmanipulated rats served as controls. Micropuncture was performed in the left kidney during control and 15% glycine infusion periods, 45 days after surgery. Arterial pressure was higher in hypertensive rats (160.3 mm Hg) than in controls (103.8 mm Hg) and rats with renal ablation (125 mm Hg; p less than 0.05). Higher values of single-nephron glomerular filtration rate and single-nephron plasma flow in rats with renal ablation (63.0, 223.7 nl/min) and hypertension (46.1, 239.7 nl/min) than in controls (28.8, 94.9; p less than 0.05) demonstrated the presence of hyperfiltration. However, glomerular pressure was elevated only in hypertensive rats (40.1 mm Hg), when compared to controls (32.7 mm Hg; p less than 0.05) and rats with renal ablation (33.4 mm Hg; p less than 0.05). Glycine increased single-nephron glomerular filtration rate and single-nephron plasma flow in control rats by 76 and 65%; rats with renal ablation had only partial responses, 35% and 23%, respectively, whereas in hypertensive rats the response was completely abolished. Glycine detected hyperfiltration and unmasked a dysfunction of preglomerular vessels that was greater in hypertensive rats and could contribute to the rise in glomerular pressure and flow and thereby to glomerular damage.

Animals↗
PubMed1986

Hemodynamic and metabolic effects of the calcium channel blocking agent nitrendipine.

In an open crossover comparison of propranolol and nitrendipine, 19 patients with hypertension received 40 to 160 mg propranolol and 5 to 20 mg nitrendipine twice a day. Mean (+/- SD) predose supine blood pressure fell from 145/98 +/- 11/7 to 132/88 +/- 12/8 mm Hg with propranolol and to 135/92 +/- 11/9 mm Hg with nitrendipine. Resting heart rate was reduced by propranolol but was unchanged 12 hours after nitrendipine dosing. Neither propranolol nor nitrendipine altered plasma glucose or insulin after oral glucose. Propranolol significantly increased fasting triglyceride levels and reduced high-density lipoprotein cholesterol levels, but nitrendipine induced no change. Propranolol reduced and nitrendipine increased plasma renin activity after exercise. Peak plasma nitrendipine levels were dose proportional and occurred at 1 to 2 hours after dosing, whereas peak blood pressure reductions occurred 4 hours after the last dose of nitrendipine and were associated with mean increases in heart rate. Nitrendipine is almost equivalent in hypotensive effect to propranolol, but nitrendipine increases plasma renin activity after exertion and may produce transient tachycardia. However, nitrendipine does not cause unwanted metabolic effects.

Administration, Oral↗
PubMed1986

Evaluation of renal functional reserve of contralateral kidney of two-kidney, one clip Goldblatt hypertensive rats.

To evaluate the presence of hyperfiltration in two-kidney, one clip (2K, 1C) Goldblatt hypertensive rats, micropuncture studies of the unclipped kidney were used to examine renal functional reserve (RFR) with glycine (G) infusion in normal (N) rats and 2K, 1C rats. Systemic hypertension in 2K, 1C rats was associated with significantly increased values of single-nephron glomerular filtration rate (SNGFR), glomerular plasma flow (QA) and glomerular capillary hydrostatic pressure (PGC) when compared with N rats. Glycine infusion produced a marked increase in SNGFR, QA and whole-kidney GFR in N rats. In contrast, no changes were observed in these parameters in 2K, 1C rats. Lack of response in 2K, 1C rats was related to the failure of renal vessels to dilate during G infusion. These results suggest that loss of renal functional reserve in systemic hypertension is dependent on an abnormal function of renal vascular resistances.

Animals↗
PubMed1986

Effect of captopril and hydrochlorothiazide on glomerular haemodynamics and histological damage in Goldblatt hypertension with partial renal ablation.

Increased glomerular capillary pressure (GCP) mediates glomerular damage in hypertension. The efficacy of captopril, an angiotensin converting enzyme (ACE) inhibitor, and captopril-hydrochlorothiazide (captopril-TZ) in lowering GCP and preventing glomerular damage was evaluated in rats with two-kidney, one clip (2K, 1C) Goldblatt hypertension and partial ablation of the unclipped kidney. Thirty days after surgery nine rats received captopril, 11 received captopril-TZ and eight served as untreated control rats. Sixty days later systemic hypertension was associated with increased GCP and severe structural damage in the unclipped kidney of C rats. Captopril lowered arterial pressure (AP), and prevented the rise in GCP and structural lesion. Captopril-TZ decreased AP and GCP to a greater extent, but did not reduce structural damage further. Captopril lowered GCP, preventing structural damage; greater reduction of GCP with captopril-TZ did not provide further protection.

Animals↗
PubMed1984

Comparative effects of propranolol and prazosin upon serum lipids in thiazide- treated hypertensive patients.

Earlier reported thiazide-induced changes in serum lipid concentrations were confirmed with increased triglyceride and total cholesterol levels. However, lipoprotein cholesterol ratios were unchanged. Propranolol caused further increases in triglyceride and very low-density lipoprotein cholesterol, and lowered high-density lipoprotein cholesterol and the high-density lipoprotein:total cholesterol ratio. With the addition of prazosin to the polythiazide regimen, there was a significant increase in serum high-density lipoprotein cholesterol when compared with the placebo.

Adult↗
PubMed1983

Graft replacement of the thoracic aorta with a sutureless technique.

A sutureless intraluminal graft requiring only ligature fixation was used for replacement of the thoracic aorta in 8 patients. The graft was deployed in the ascending and descending thoracic aorta as well as in the arch. It was used for aortic dissection and atherosclerotic aneurysms. Insertion was easy and relatively quick. Fixation was secure and without serious complications. Seven of the 8 patients became long-term survivors.

Aged↗