Browsing by Author "ALBERTINI, R"
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- ItemASSESSMENT OF A UNIVERSITY SCIENTIFIC CAPABILITIES AND PROFILE - THE CASE OF THE FACULTY OF BIOLOGICAL SCIENCES OF THE PONTIFICIA-UNIVERDIDAD-CATOLICA-DE-CHILE(1995) KRAUSKOPF, M; VERA, MI; ALBERTINI, RThe scientific capabilities and performance profiles of the Faculty of Biological Sciences of the Pontificia Universidad Catolica de Chile were assessed building performance indicators from the ISI's Chile-National Citation Report, 1981-1992. Consistent with the educational goals of the Faculty, the scientific activity which nurtures graduate training, especially at the doctoral level, was examined field by field and compared to Chilean and World scores. The approach rendered a portrait of the Faculty which depicts, trends, strengths and weaknesses, and standards for the evaluation of future activity. The study shows a very competitive performance in most of the fields, relative to national and world average achievements. A remarkable finding was the outstanding performance in applied fields, such as medical and agricultural sciences, and also in biotechnology, with shows that when good basic science takes place, high level goal oriented research also occurs.
- ItemBLUNTING EFFECT OF PEPSANURIN INTRODUCED IN THE DUODENUM ON THE ATRIAL-NATRIURETIC-PEPTIDE DIURETIC ACTION IN RATS(1993) CROXATTO, HR; BORIC, MP; ROBLERO, JS; ALBERTINI, RPepsanurin (PU) is a peptide(s) obtained by pepsin hydrolysis of human plasma or its globulin fraction. We have reported that the accelerated renal excretory rate induced by atrial natriuretic peptide (ANP) can be considerably blunted by PU either in the intact rat or in the isolated perfused rat kidney. We explored whether or not PU can be part of a signaling mechanism originated in the digestive tract, involved in the regulation of water and electrolyte homeostasis. PU obtained either from human (0.5 ml) or rat plasma (0.25-0.5 ml) administered into the duodenal lumen of rats, counteracted significantly the diuretic-saluretic action ot a 0.5- mug bolus of ANP, reproducing qualitatively the effect of its intraperitoneal administration. Human PU reduced the ANP-stimulated renal excretion by 67-90% for Na (P < 0.001) and by 35-54% for water (P < 0.02-P < 0.001); the inhibition induced by rat PU was 45-96% for Na (P < 0.05-P < 0.01) and 35-65% for water (P < 0.05-P < 0.01). Rat PU (0.5 ml) abolished the rise of glomerular filtration rate induced by ANP without affecting fractional Na excretion. All the samples tested decreased K excretion, but in some experiments, the difference did not reach statistical significance. Contrary to the effect of PU, the introduction in the duodenum of (i) isotonic glucose solution, (ii) hydrolysate of bovine serum albumin, or (iii) hydrolysate of casein prepared after the same procedure yielding PU from plasma failed to produce an inhibition of the ANP stimulation of renal excretory rate. In addition, human plasma incubated at 37-degrees-C for 24 to 48 hr, prior to pepsin digestion, did not yield PU, which indicates that PU is generated from a substrate sensitive to endogenous enzymes and/or that its stability is vulnerable to endogenous enzymes.
- ItemEFFECT OF RENAL NERVE-STIMULATION ON URINE AND TISSUE KININOGENASE ACTIVITY IN CATS(1981) ALBERTINI, R; DEGUEVARA, RL; ASENJO, F; BORIC, M
- ItemINHIBITION OF ATRIAL-NATRIURETIC-PEPTIDE INDUCED NATRIURESIS BY PLASMA HYDROLYSATES CONTAINING PEPSANURIN(1992) BORIC, MP; CROXATTO, HR; ALBERTINI, R; ROBLERO, JSThe specificity of antidiuretic actions of pepsanurin, a peptidic fraction obtained by pepsin hydrolysis of plasma, was studied in anesthetized rats and in isolated perfused rat kidneys. Pepsanurin was obtained from fresh dialyzed human plasma digested with pepsin (2,400 units/ml, 18 hours at 37-degrees-C, pH 2.5), deproteinized (10 minutes at 80-degrees-C), and centrifuged. In the rat, intraperitoneal injections of pepsanurin (0.5 ml/100 g body wt) significantly inhibited the effects of an intravenous bolus of atrial natriuretic peptide (ANP) (0.5-mu-g) on water, sodium, and potassium excretion without altering systemic blood pressure. In addition, pepsanurin abolished the peak in glomerular filtration rate and reduced the ANP-induced rise in fractional sodium excretion. Pepsanurin also inhibited the natriuretic effects of amiloride (10-mu-g/100 g body wt i.v.) without changing glomerular filtration rate, but it did not inhibit the potassium-retaining effect of amiloride. In contrast, pepsanurin had no effect on basal urinary excretion, and it did not affect the diuretic response induced by furosemide (doses of 25, 50, or 100-mu-g i.v.). Control peptidic hydrolysates prepared from human plasma preincubated 48 hours at 37-degrees-C (PIPH), bovine albumin (BSAH), or human albumin did not inhibit ANP, amiloride, or furosemide. In perfused kidneys, pepsanurin significantly and reversibly reduced sodium and water excretion. Furthermore, pepsanurin, but not PIPH or BSAH, blocked the natriuretic and diuretic effects of ANP. These results support the existence of a specific plasma substrate able to release a peptide or peptides that counteract distal tubule diuresis and natriuresis by an intrarenal mechanism.
- ItemINHIBITORY EFFECT OF RENIN EXTRACTS UPON URINARY KALLIKREIN EXCRETION(1978) CROXATTO, HR; ROJAS, M; CORTHORN, J; ALBERTINI, R; ROBLERO, JI.p. injections of 1-5 IU of renin purified extracts, obtained either from hog or rat kidneys, in hyperhydrated rats receiving distilled water or 0.4% NaCl (5% body wt) produce not only a striking increase in the Na excretion rate but a very significant decrease in kallikrein excretion as well. In the urine excreted in the 1st h after renin administration kallikrein practically disappeared in the urine; with higher doses the inhibitory effect was very marked and lasted up to 120 min. In the same rats under a 2nd hyperhydration, not associated with renin injection, kallikrein tends to return to control levels.
- ItemISOLATION AND CHARACTERIZATION OF RAT PLASMA GLANDULAR KALLIKREIN(1985) MASFERRER, J; ALBERTINI, R; CROXATTO, HR; GARCIA, P; PINTO, IA method was developed to purify glandular kallikrein present in rat plasma by using Sepharose-Aprotinin affinity chromatography and elution of the enzyme with p-aminobenzamidine. The isolated enzyme liberated kinins for kininogen II of low MW (sp. act. 14 ng kinins/min .times. mg) and p-nitroaniline (pNA) from the substrate S-2266 (sp. act. 1.23 nmol pNA/min .times. mg); it was inhibited by aprotinin, benzamidine and rat urinary antikallikrein antibody but not by ovomucoid. In polyacrylamide gel electrophoresis, the enzymatic activities of the preparation were associated with 2 light protein bands of MW equal to that of urinary kallikrein (35,000 daltons). Using this method, the recovery of [125I]kallikrein added to the plasma was 82-88%. The concentration of the enzyme in normal rat plasma was equivalent to 6.1 .+-. 2.1 ng kallikrein/ml. The mean value found in nephrectomized rats was 20.0 .+-. 6.3 ng kallikrein/ml. This increment was highly significant (P < 0.001). These results confirm the presence of glandular kallikrein in plasma which had been detected by other methods; they also demonstrate that the material purified from plasma is enzymatically active, suggesting that kallikrein may play a biological role in the control of blood circulation.
- ItemRENAL URINARY KALLIKREIN IN NORMOTENSIVE AND HYPERTENSIVE RATS DURING ENHANCED EXCRETION OF WATER AND ELECTROLYTES(1976) CROXATTO, HR; ALBERTINI, R; ARRIAGADA, R; ROBLERO, J; ROJAS, M; ROSAS, R
- ItemSYMPATHETIC NERVOUS-SYSTEM MEDIATES URINARY KALLIKREIN EXCRETION IN CONSCIOUS RATS(1987) ALBERTINI, R; VARGAS, L; OLIVERI, P; PARDO, F; PAREDES, MC