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Biomedical subjects

E Escobar

Publications and source records attributed to E Escobar.

At least 19 recordsLinked to original sources
PubMed2005

Blockage of angiotensin II type I receptor decreases the synthesis of growth factors and induces apoptosis in C6 cultured cells and C6 rat glioma.

Angiotensin II (Ang II) is a main effector peptide in the renin-angiotensin system and participates in the regulation of vascular tone. It also has a role in the expression of growth factors that induce neovascularisation which is closely associated to the growth of malignant gliomas. We have shown that the selective blockage of the AT1 receptor of angiotensin inhibits tumour growth, cell proliferation and angiogenesis of C6 rat glioma. The aim of this study was to study the effects of the blockage of AT1 receptor on the synthesis of growth factors, and in the genesis of apoptosis in cultured C6 glioma cells and in rats with C6 glioma. Administration of losartan at doses of 40 or 80 mg kg(-1) to rats with C6 glioma significantly decreased tumoral volume and production of platelet-derived growth factor, vascular endothelial growth factor and basic fibroblast growth factor. It also induced apoptosis in a dose-dependent manner. Administration of Ang II increased cell proliferation of cultured C6 cells which decreased by the administration of losartan. Our results suggest that the selective blockage of AT1 diminishes tumoral growth through inhibition of growth factors and promotion of apoptosis.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2004

Asphalt volcanism and chemosynthetic life in the Campeche Knolls, Gulf of Mexico.

In the Campeche Knolls, in the southern Gulf of Mexico, lava-like flows of solidified asphalt cover more than 1 square kilometer of the rim of a dissected salt dome at a depth of 3000 meters below sea level. Chemosynthetic tubeworms and bivalves colonize the sea floor near the asphalt, which chilled and contracted after discharge. The site also includes oil seeps, gas hydrate deposits, locally anoxic sediments, and slabs of authigenic carbonate. Asphalt volcanism creates a habitat for chemosynthetic life that may be widespread at great depth in the Gulf of Mexico.

Animals↗
PubMed2002

Hypertension and coronary heart disease.

The association of hypertension and coronary heart disease is a frequent one. There are several pathophysiologic mechanisms which link both diseases. Hypertension induces endothelial dysfunction, exacerbates the atherosclerotic process and it contributes to make the atherosclerotic plaque more unstable. Left ventricular hypertrophy, which is the usual complication of hypertension, promotes a decrease of 'coronary reserve' and increases myocardial oxygen demand, both mechanisms contributing to myocardial ischaemia. From a clinical point of view hypertensive patients should have a complete evaluation of risk factors for atherosclerosis, damage of arterial territories other than the coronary one, and of the extension and severity of coronary artery involvement. It is important to emphasise that complications and mortality of patients suffering a myocardial infarction are greater in hypertensive patients. Treatment should be aimed to achieve optimal values of blood pressure, and all the strategies to treat coronary heart disease should be considered on an individual basis.

Animals↗
PubMed2000

[Prevention of cardiovascular diseases: should the same criteria be applied in Latin America and Europe and North America?].

The prevention of cardiovascular diseases is based on the management of known cardiovascular risk factors by pharmacological means or by modifying lifestyles. A reduction in cholesterol levels is associated with a lower incidence of cardiovascular events and mortality, in both primary or secondary prevention trials. A reduction in blood pressure also leads to a decrease in acute myocardial infarction and the incidence of stroke. Regular exercise is associated with better disease free survival and the effects of smoking cessation are well known. High homocysteine levels are also associated with cardiovascular disease. However, there are no prospective clinical trials showing a beneficial effect of homocysteine reduction on cardiovascular mortality. A change in the type of dietary fat should also be beneficial, but this has not been proven in prospective clinical trials. In Chile, cardiovascular diseases are the leading cause of death among adults and the prevalence of cardiovascular risk factors, including hyperhomocysteinemia is similar to that of European or North American populations. Successful primary and secondary prevention programs to manage these risk factors have been developed in Chile. Therefore, the criteria applied in North America and Europe for the prevention of cardiovascular diseases, should be applied with slight modifications, in Latin American Countries.

Canada↗
PubMed2000

[The Beca's in Chilean psychiatry].

The Chilean psychiatrists, Manuel and Francisco Beca, father and son, who lived at the turn of the XIX century and in the first half of the XX respectively, dedicated their lives to the care of mental patients and to the teaching of psychiatry, contributing in their own way and time to the development of the specialty in Chile. Manuel Beca, a clinician, published the first mental patient statistics and Francisco, an academic, became professor of Psychiatry at the Catholic University. Although they dedicated themselves to different fields in the area of mental health, such as clinical research and teaching, both have outstanding merits to become a part of the historical memory of Chilean psychiatry.

Chile↗
PubMed1999

Heart rate variability in severe aortic stenosis.

BACKGROUND AND AIM OF THE STUDY: Autonomic dysfunction may be a risk factor for the generation of arrhythmias and sudden death in patients with severe aortic stenosis; thus, patients with this condition were studied to assess cardiac autonomic function. METHODS: Twelve patients (five males, seven females; mean age 63 +/- 13 years) with severe symptomatic aortic stenosis before and after aortic valve replacement, were compared with a control group matched by age and sex. In the study group, mean fractional shortening was 36.5 +/- 5% and maximal aortic gradient 94.7 +/- 12 mmHg, assessed echocardiographically. Autonomic dysfunction was evaluated by following heart rate variability in both time and frequency domains. Spectral analysis was assessed at very low frequency (VLF: 0.017-0.05 Hz), low frequency (LF: 0.05-0.15 Hz) and high frequency (HF: 0.15-0.50 Hz). Heart rate variability was analyzed during three intervals, between 6:00-8:00 am (morning), 14:00-16:00 (afternoon) and 02:00-04:00 (night), and re-evaluated at 8-10 months after aortic valve replacement. RESULTS: Compared with controls, patients with aortic stenosis presented a significantly lower heart rate variability in the morning and afternoon, analyzed either by time or frequency domain: 50 +/- 22 versus 132 +/- 52 ms (p < 0.05); VLF 5.0 +/- 1.5 versus 7.9 +/- 1.4 ln (ms)2 (p < 0.05); LF 4.9 +/- 1.7 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05); HF 5.3 +/- 1.4 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05). Results at night showed a similar tendency, but were not statistically significantly different. At 8-10 months after aortic valve replacement, heart rate variability was increased significantly during the morning, from 50 +/- 22 to 79.5 +/- 22 ms (p < 0.05); VLF from 5.0 +/- 1.5 to 6.7 +/- 0.8 ln (ms)2 (p < 0.05); LF from 4.9 +/- 1.7 to 6.2 +/- 1.3 ln (ms)2 (p < 0.05). HF values tended to increase, though not significantly so. During the remainder of the day there was also a non-statistically significant increment in all values of heart rate variability. CONCLUSIONS: The study results suggest that patients with severe symptomatic aortic stenosis present with autonomic dysfunction that tends to normalize within the first year of valve replacement.

Aortic Valve Stenosis↗
PubMed1999

[The first Chilean journal of psychiatry, neurology and forensic medicine].

This historical review refers to the first Chilean Journal of Psychiatry, Neurology and Forensic Medicine, that was published for the first time in July 1917, and allows to get acquainted of the knowledge level of those times. The publication was in charge of physicians from "Casa de Orates", the Clinic of Nervous and Mental diseases and the Chair of Forensic Medicine. The journal publication was interrupted in 1919. More than half of papers were of psychiatric topics, reviewing a disease or updating treatments. Analysis of psychiatric themes showed a special interest for problems related to hospital management and mental health.

Chile↗
PubMed1998

Subcellular distribution of prostaglandin-E2 and prostaglandin-F2 alpha in atrial tissue from patients with mitral valve disease.

The distribution of prostaglandin-E2 (PGE2) and prostaglandin-F2 alpha (PGF2 alpha) was studied in subcellular fractions isolated from homogenates of human atrial fresh tissue by differential centrifugation. Right and left atrial samples were excised from the same heart of six patients with mitral valve disease at the time of open heart surgery. The atrial fractions investigated were mitochondrial (8,500 g pellet), microsomal (100,000 g pellet) and cytosol soluble (100,000 g supernatant) fractions. After extraction of prostaglandins from the three atrial fractions and separation of PGE from PGF series by chromatography on silicic acid column, these prostaglandins were measured by radioimmunoassay. The results showed that PGE2 and PGF2 alpha were located mainly in the soluble cytosolic fraction of right and left atrial tissue (p < 0.001). Furthermore, the prostaglandins levels were higher in left than in right atria of these patients (p < 0.001). The relation between prostaglandins heart generation in response to elevated work load of mitral valve disease is discussed.

Adult↗
PubMed1997

[Demand for consultations at the Emergency Service of the "Dr. José Horwitz B" Psychiatric Institute in Santiago, Chile: comparison between 1988 and 1994].

BACKGROUND: In the last decade, there have been changes in the prevalence of specific psychiatric disorders. AIM: To study the diagnoses and demographic features of patients consulting the emergency wards of a public psychiatric hospital in Santiago during 1994 as compared with those of patients consulting in 1988. MATERIALS AND METHODS: A random sample of 439 patients charts, corresponding to 3% of all consultations during 1994, were analyzed. The results were compared with consultations during 1988, analyzed in a previous study. RESULTS: During 1994, patients were older, came alone to the emergency wards and consulted during the night with greater frequency than during 1988. In both years psychosis were the main cause of consultation. Compared to 1988, during 1994 there was an increase in the frequency of affective disorders (16 and 12% of all consultations respectively) and substance abuse (15 and 3% respectively). CONCLUSIONS: The increase in consultations due to affective disorders and substance abuse in 1994 is in accordance with changes in the epidemiological profile of psychiatric disorders in Santiago.

Adolescent↗
PubMed1996

Stimulation of albumin synthesis in rat hepatocytes by ascites from patients with cirrhosis.

Hepatocyte growth factor (HGF), identified in ultrafiltered ascites and plasma from patients with cirrhosis, enhances the DNA synthesis in adult rat hepatocytes cultured at low cell density. This study was carried out to investigate the effect of ascites and plasma from patients with cirrhosis on liver-specific functions such as albumin synthesis in adult rat hepatocytes cultured at confluent-cell density. Ultrafiltered ascites from patients with cirrhosis and its ascitic protein, partially purified by fractionation with ammonium sulfate and gel filtration on Sephadex G-200, stimulated albumin synthesis in a dose-dependent manner in the presence of 10(-8), M dexamethasone. This effect was greater than that of 10(-7) M insulin and similar to that of 10(-7) M dexamethasone, but was additive with that of insulin plus dexamethasone. The molecular weight of the ascitic factor was estimated as 100,000 to 150,000, corresponding to that of HGF purified from cirrhotic ascites. Moreover, the partially purified ascitic factor markedly stimulated DNA and protein synthesis in hepatocytes. These findings suggest that the ascitic factor may act as HGF by stimulating hepatocyte DNA and albumin synthesis in a cell density-dependent manner.

Aged↗
PubMed1996

[Isolation and some properties of the proteinase atroxin from the venom of the snake Bothrops atrox].

A proteolytic enzyme from the venom of Bothrops atrox snake was isolated. It was designed as Atroxin, and three chromatography steps were used to purification: ion exchange chromatography on DEAE-Sephadex A-50 equilibrated with 0.05 M Tris HCl buffer, 1 mM CaCl2 pH 7.4, followed by gel filtration on Sephadex G-50 and Sephadex G-100, respectively, using the same buffer. The enzyme was recovered with a 7.4 folds and 11% of yield. It had a high activity on casein being 7.4 optimus pH. A molecular weight was 19.9 Kd calculated by polyacrilamide gel electrophoresis, and head treatment showed that the enzyme preserves its activity in the range of 37-45 degrees C, while it was decrease when the temperature values were higher. On the other hand, 0.133 mumoles of Ca2+ and Mg2+, and Zn2+ ions (0.266 mumoles) were activators, while EDTA (0.20 mumoles) and sodium azide (0.053 mumoles) were inhibitors. The enzymatic activity was not affected by glicerol (1.33 mumoles) and phenyl methyl sulphonyl fluoride (PSMF) (0.16 mumoles). In addition, iodoacetic acid (0.08 mumoles) was slight inhibitor, but 0.16 mumoles of p-tosyl-1-lysine chloromethyl ketone (TLCK) was activator. Biological assays on mice showed that atroxin produced hemorrhagic and necrosis after 24 h of injection, which was increased by 5 mM calcium chloride.

Animals↗
PubMed1995

Interventional cardiology in Chile.

In Chile the first experiences with cardiac catheterization began very shortly after Forssmann's first studies. Percutaneous coronary balloon angioplasty (PTCA) was first performed in 1982. Despite a progressively great interest and training of physicians in invasive cardiology there are still restrictions in its development. Most private institutions have modern facilities but their caseloads, ever increasing, are still limited because they take care of only 35% of the population. Public institutions are limited because of funding, and some are just developing PTCA. The situation has improved recently because of deals between the private and public systems. Experience with newer devices is even more limited.

Angioplasty, Balloon, Coronary↗
PubMed1994

Effect of NPPB on chloride (Cl-) transport in distal colon of potassium (K+) adapted rats.

Secondary hyperaldosteronism enhances the rate of K secretion in distal colon, at least in part, through the stimulation of Na(+)-K(+)-Cl- cotransport across the basolateral membrane. To maintain a constant intracellular Cl- activity an increase in Cl- transport out of the cell must be assumed. We explored, under amiloride 10(-4) M and short circuited conditions, conductive pathways for Cl- exit in the distal colon of K(+)-adapted rats by means of a putative Cl- channel blocker, NPPB (5-nitro-2(3-phenyl-propylamino-benzoate. Results prior to NPPB showed an increase in JClms after K+ loading from 5.84 +/- 0.66 to 8.33 +/- 0.86 and JClsm from 4.77 +/- 0.55 to 8.16 +/- 0.96 microEq h-1 cm-2 (P < 0.001), when compared with controls. Net fluxes were not different between groups. Luminal NPPB in K+ adaptation resulted in a decrease of JClsm, from 7.85 +/- 1.5 to 6.69 +/- 1.5 microEq h-1 cm-2 (P < 0.05). There were no changes in both unidirectional Cl- fluxes in controls under luminal NPPB and in potential difference (V) and short-circuit current (Isc) under any condition. Finally, K+ adaptation resulted in an increase of luminal cyclic AMP (cAMP) concentration (0.09 +/- 0.02 to 0.20 +/- 0.03 pmol 100 microliters -1, P < 0.005), when compared with control rats. The data may suggest a transcellular recycling of Cl- and an activated NPPB inhibitable serosal to mucosal Cl- pathway on luminal membrane in the K+ adapted state, possibly mediated by an increase in cAMP production.

Adaptation, Physiological↗
PubMed1993

Water handling in Caco-2 cells: effects of acidification of the medium.

Caco-2 cells were cultured on permeable supports. At confluence the minute-by-minute net water movement (Jw) was automatically recorded. Simultaneously, unidirectional [14C]mannitol, 22Na+, and/or 36Cl- fluxes and transepithelial resistances were measured. The water and mannitol permeabilities went progressively down between 9 and 16 days after seeding and then stabilized. In this last condition the hydrostatic permeability coefficient (Phydr) was 2.67 +/- 0.31 cm s-1 while the osmotic permeability coefficient (Posm) was 0.0017 +/- 0.0004 cm s-1. Phydr but not Posm was dependent on the temperature and on the presence of Na+ in the medium. A net secretory Jw was observed 16 days after seeding, in the absence of any osmotic, hydrostatic or chemical gradient. This secretory Jw was associated with net Cl- (1.43 +/- 0.43 muequiv h-1 cm-2) and Na+ (1.05 +/- 0.35 muequiv h-1 cm-2) secretions. Amiloride reduced, in open-circuit conditions, both Na+ and Cl- apical to basal fluxes, thus enhancing the net Na+ and Cl- exit. Acidification of the medium (pH 6.2) reversibly increased water and mannitol permeabilities in 10-day-old cultures. In 16-day-old cultures the same shift in medium pH did not change mannitol permeability, while stimulating water secretion. These results, obtained in the absence of supracellular structures (villae, crypts) and subepithelial components (muscular, vascular and conjunctive tissues) indicate that paracellular and transport-associated water pathways are sensitive to changes in the pH of the medium in Caco-2 cell layers.

Adenocarcinoma↗
PubMed1993

Water and ion coupling in the rat cecum during dietary potassium loading.

The transepithelial net water movement (Jw) was minute by minute recorded in the cecum of Wistar rats adapted to a high potassium diet (HKD). The potential difference (PD), short circuit current (SCC) and unidirectional 22Na, 36Cl, and 89Rb fluxes were also measured. The hydrostatic and osmotic permeabilities were not modified by potassium adaptation when a standard bicarbonate buffer was employed. Potassium adaptation implicated the development of a secretory, transport-associated Jw (Jwt), associated to an increase in transepithelial PD, SCC and net sodium transport. Contrary to the case of control rats, no net chloride transport was observed in HKD rats. The secretory Jwt compensated, in the presence of sodium, chloride and bicarbonate, an absorptive Jwt. Water secretion was coupled to net potassium secretion. Replacement of chloride by sulphate ions was paralleled by the development of a net absorptive Jw and by increases in the transepithelial Pd and hydrostatic permeability. Replacement of the bicarbonate buffer by a tris-hepes buffer made drop both the observed absorptive Jw and PD amiloride sensitive Na+ entry was observed.

Animals↗
PubMed1993

[Treatment of mild hypertension with captopril and captopril with hydrochlorothiazide. Impact on blood pressure values and quality of life].

The effects of captopril alone or associated to hydrochlorothiazide on blood pressure and quality of life was studied in 244 hypertensive subjects. After a medication wash out period of 30 days (and 7 additional days when diuretics were used) patients were treated initially with captopril 25 mg b.i.d. (scheme A); if blood pressure was not normalized, hydrochlorothiazide 25 mg o.d. was added (scheme B) and the dose of captopril was increased to 50 mg bid (scheme C) in a stepwise fashion. Sixteen patients (6.6%) were lost from follow up; in the rest a significant reduction of blood pressure was obtained at the end of the treatment period (from 163/98.9 +/- 19.7/3.1 to 143/85 +/- 12.7/6.7 p < 0.05), without changes in cardiac frequency. Using captopril alone, blood pressure was normalized at 15 and 75 days in 62.9 and 70.6% of patients respectively. With captopril plus hydrochlorothiazide blood pressure was normalized in 80.9% of patients. Quality of life improved significantly from of 42.8 +/- 1.7 to 50.7 +/- 15 score points (p < 0.05) secondary effects were observed in 7.4% of patients. It is concluded that captopril alone or associated to hydrochlorothiazide is effective in the treatment of mild hypertension, produces few secondary effects and improves the quality of life.

Adult↗