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J Urzúa

Publications and source records attributed to J Urzúa.

At least 19 recordsLinked to original sources
PubMed2000

Cytochemical and electrophoretic study of the stallion epididymal glycoproteins.

It has been suggested that proteins produced in specific regions of the epididymis, mostly androgen dependent glycoproteins, are involved in the sperm maturation process. In the present work, the glycoconjugated distribution pattern and the electrophoretic characteristics of the stallion epididymal proteins were examined using lectin probes. The identification in the luminal fluid of some new proteins, probably synthesized and secreted by the epididymis, is an important initial step to investigate their interaction with the stallion sperm membrane. The binding of FITC-lectins (ConA, WGA, LPA, UEA, RCA, HPA) confirmed the presence of macromolecules containing carbohydrate residues in the epithelial cells with a distribution and relative density that was dependent on the epididymal region analyzed. The epithelium displayed affinity for more than one lectin, indicating diversity in the exposed sugar residues. The electrophoretic pattern of proteins obtained from ductus efferentes, corpus and cauda epididymis differed not only from those of the homologous blood serum, but also among the different epididymal regions. The most prominent bands correspond to 66, 55, 45 and 14 kDa proteins, present in different relative concentrations, in the three analyzed regions. A major band of 36 kDa was observed in the cauda epididymis region. The relative concentrations of protein bands of Mw 45, 36, 32, 20 and 18 kDa were significantly increased towards the distal regions of the ductus. The proteins of Mw 66, 55 and 14 kDa showed a relative higher concentration in the efferent ducts, decreasing to 25-30% in the cauda epididymal regions. The Mw 70, 66, 55, 45, 36, 32, 29, 23, 21, 18 and 14 kDa protein bands gave positive PAS reaction indicating that it corresponds to glycoproteins. Mannose residues were detected in the 70, 66, 55, 45, 36 and 32 kDa proteins. WGA-FITC binds to protein bands of Mw 70, 55, 45, 36, 32, 29, 25 and 24 kDa, suggesting the presence of N-linked glycoproteins. However, based on the resistance to the neuraminidase treatment, we suggest that the stallion epididymis contains both O- and N-glycoconjugates, probably in the N-acetyl O-diacetyl form. Although sperm maturation is an androgen-dependent process, no striking differences were detected in the SDS-PAGE obtained from animals in breeding and non-breeding seasons.

Animals↗
PubMed2000

[Carotid endarterectomy under regional anesthesia: initial experience].

BACKGROUND: Endarterectomy is the treatment of choice for internal carotid artery critical stenosis. Some authors have proposed that the use of regional anesthesia has advantages over general anesthesia. AIM: To report our initial experience with carotid endarterectomy under regional anesthesia. PATIENTS AND METHODS: Between 1998 and 1999, patients with critical carotid artery stenosis, asymptomatic or with transient and recovered symptoms, were selected. A C2, C3, C4 root deep cervical block and superficial block was performed, using a mixture of lidocaine and bupivacaine. A carotid endarterectomy with patch and without routine shunt insertion, with standard and neurological monitoring, was performed. RESULTS: During the study period, 94 carotid endarterectomies were done, 22 under regional anesthesia in 21 patients (12 male, age range 58-90 years old). Ninety five percent had hypertension, 52% smoked and 38% had renal dysfunction. One patient was converted to general anesthesia. Seventeen patients were discharged within 48 hours of the procedure and the rest, within 72 hours. There was no mortality or complications. CONCLUSIONS: Endarterectomy under regional anesthesia is less invasive, has excellent results and is well accepted by patients.

Aged↗
PubMed2000

Changes in the plasma membrane proteins of stallion spermatozoa during maturation in the epididymis.

The present paper reports modifications in the electrophoretic and cytochemical characteristics of mature and immature stallion spermatozoa. Some sperm surface glycoproteins (36, 32, 29, 21, 20, 18 kDa) detected in cauda epididymidis spermatozoa, were either absent or present in a very low relative concentration in immature sperm cells. A major 14 kDa protein band, observed in sperm extracts obtained from ductus efferentes, progressively decreased along the epididymal ductus. The nature and distribution of carbohydrate residues on the sperm membrane, during epididymal maturation, was also studied by use of lectin probes. Some protein bands bound concanavalin A while others, as the 36, 32 and 20 kDa proteins, exhibited higher affinity for WGA lectin. The distribution and relative density of mannose-, galactose-, N-acetylglucosamine-, N-acetylgalactosamine-, fucose- and sialic acid-containing macromolecules showed a characteristic pattern depending on the sperm membrane domain and on its origin. Some sperm surface domains displayed affinity for more than one lectin, indicating a diversity in their exposed carbohydrate residues, whereas others bound only one or no lectin. The passage of spermatozoa through the epididymidis was accompanied by changes in the accessibility or abundance of lectin ligands. Some lectins (UEA, WGA, LPA) gave stronger reaction in mature spermatozoa, while others (RCA, WFH, PNA) stained better immature spermatozoa. This remodeling of sperm surface molecules is probably a consequence of interactions between spermatozoa and the epididymal secretions, and may reflect addition or adsorption of new molecules, space configurations changes or biochemical modifications of pre-existing compounds. Our results suggest that the distribution and density of terminal oligosaccharidic residues on the sperm plasma membrane have species-specific characteristics. These post testicular developmental changes may be of significance in the overall understanding of the stallion fertility.

Animals↗
PubMed1999

[Opioids and the immune system].

The immune response is partly regulated by the nervous system, that involves endogenous opioids, stimulating or depressing immune responses. Opioids modulate immune response by indirect and direct mechanisms. Indirect modulation occurs when the activation of opioid receptors within the nervous system modifies the activity of neuroendocrine axes or neurotransmission pathways. Direct modulation results from the effects of opioids on immune system cells. This requires the expression of membrane opioid receptors in these cells. Immunomodulating effects of morphine would be a result of the integration of indirect and direct effects. In animal models, morphine transiently depresses cellular and humoral immunity. In humans, morphine has similar effects; however, the real impact of morphine administration on the immune response in clinical situations in not yet known.

B-Lymphocytes↗
PubMed1998

Estimation of cardiac function from computer analysis of the arterial pressure waveform.

This paper presents a method for estimating parameters of a cardiovascular model, including the left-ventricular function, using the sequential quadratic programming (SQP) and the least minimum square (LMS) algorithms. In a first stage, a radial arterial-pressure waveform with corresponding cardiac output are used to automatically seek the set of parameters of the diastolic model. Computer simulation of the model using these parameters generate a pressure waveform and a cardiac output very close to those used for the estimation. In a second stage, the estimated arterial load parameters are used to select the best left-ventricular model function, from four different possibilities, and to estimate its optimum parameter values. The method has been tested numerically and applied to real cases, using data obtained from cardiovascular patients. It has also been subjected to preliminary validation using data obtained from laboratory dogs, in which cardiovascular function was artificially altered.

Algorithms↗
PubMed1998

[Coronary surgery. 20 years of follow-up].

BACKGROUND: Since the first surgical coronary revascularization done in Chile in 1971, 5000 such procedures have been performed. AIM: To assess the long term results of coronary revascularization surgery in our institution and to identify prognostic factors. PATIENTS AND METHODS: Five groups of 100 patients each, composed by the first consecutive patients subjected exclusively to coronary bypass surgery in the years 1975, 1980, 1985, 1990 and 1995 were retrospectively studied. RESULTS: Mean age of patients increased from a median of 52 years old in 1975 to 62 years old in 1995. No changes in the frequency of diabetes, hypertension, high serum cholesterol or previous myocardial infarction were observed. There was an increase in the proportion of patients with a recent (< 30 days) infarction that were operated along time. Seventy percent of patients had triple vessel disease or LMT and this proportion did not change. The number of grafts per patients increased form 1.9 to 3.4 and the use of arterial conduits from 0.18 to 0.81. Perioperative mortality remained constant and was 1.6%. Follow up information was obtained for 93% of 492 survivors. Actuarial survival at 5, 10, 15 and 20 years was 93 +/- 1, 82 +/- 2, 62 +/- 3 and 41 +/- 4% respectively. Ninety eight +/- 0.7, 89 +/- 2, 73 +/- 4 and 65 +/- 5% of patients remained free of a new myocardial infarction in the same lapses, respectively. Ninety seven +/- 1, 94 +/- 2, 76 +/- 4 and 47 +/- 7% of patients remained free of a new operation. Stepwise logistical regression analysis identified as bad prognostic factors, in decreasing order: cardiac failure, diabetes, smoking, hypercholesterolemia and age at the moment of operation. CONCLUSIONS: Coronary artery bypass surgery provides good and long lasting clinical improvement. The prognosis of patients is influenced by the presence of cardiac failure, some well known coronary risk factors and age at the moment of operation.

Aged↗
PubMed1998

[Mechanism of action of general anesthetics. Effect on ion channel proteins or on membrane phospholipids?].

General anesthesia is defined by reversible unconsciousness, lack of response to noxious stimuli, and amnesia, induced by chemical agents. Mechanisms underlying the anesthetic effect are not known. The most prevalent belief was that anesthetic drugs acted on the lipid cell membranes, based on the correlation between oil solubility and anesthetic potency. Later, it has been proposed that anesthetic agents act on specific proteins of the cellular membrane of neurons. Voltage-gated ionic channels are inhibited by anesthetic agents, being some subtypes more sensitive. Clinical concentration of anesthetic agents inhibit or stimulate excitatory or inhibitory neurotransmitter receptors, respectively. Specific receptor agonists and antagonists modify this effect. Intercellular channels (gap junctions) are also affected by anesthetic agents through direct interaction with some of their protein subunits. Thus, anesthesia would result from combined effects on specific proteins acting on neural cell excitability as well as transmission and propagation of nerve impulses.

Anesthetics, General↗
PubMed1997

[Myocardial revascularization with one and two mammary arteries: clinical results and long-term follow-up].

BACKGROUND: Coronary bypass grafts made with internal mammary artery have better long-term results than those made with saphenous vein. It is possible that the use of both mammary arteries would lead to even better results. AIM: To compare the long-term survival and the incidence of new coronary events of patients, in whom one or two mammary arteries were used as coronary bypass grafts. PATIENTS AND METHODS: One hundred and eight randomly selected patients who received one mammary artery for myocardial revascularization and 108 patients, matched for prognostic factors, who received two mammary arteries were studied. These patients were followed for a mean of 4 years (range 1 to 12 years). Operative complications, hospital mortality and long-term probability of being free of disease were compared in both groups. RESULTS: Operative mortality was similar in both groups (0.9%). Patients that received two mammary arteries had a higher frequency of operative wound complications. Long-term survival was 84% in patients who received one and 83% in patients who received two mammary arteries. The probabilities of being free of myocardial infarction (92 and 82% respectively) and angina (94 and 86% respectively) were lower in the later group. CONCLUSIONS: Patients who received two mammary arteries had a higher probability of a long term disease free survival than patients who received one mammary artery.

Disease-Free Survival↗
PubMed1997

[Abdominal aortic aneurysm: course of morbimortality of elective surgery in 20 years].

Abdominal aortic aneurysms (AAA) usually undergo progressive dilatation and eventually may rupture, complication that carries a high mortality rate. If certain clinical conditions, like operative risk and aortic diameter are met, all patients should be considered for surgical repair. Analysis of our results with the surgical treatment of asymptomatic AAA prompted this study. Out of 479 consecutive patients operated because of AAA between 1976 and 1995, 378 (79%) were electively treated. Two decades: 1976-85 (101 patients) and 1986-95 (277 patients) were compared as far as associated medical conditions, surgical procedures, complications and mortality rate. There was no difference in age, sex, risk factors and aortic diameter. During the second decade we favoured the use of aortic tube grafts (53% vs 25%, p < 0.01) and epidural anesthesia (94% vs 35%, p < 0.01). During the last decade only 53.3% of the patients received blood transfusion, compared to 95.3% during the first period (p < 0.001). Operative mortality decreased from 5.94% to 0.72% (p < 0.05). Postoperative hospital stay diminished from 11.2 +/- 8.2 to 9.6 +/- 6.3 days (p < 0.05). These results compare favourably with those reported from other academic centers and support our therapeutic approach. Our contemporary surgical results serve as a reference for future clinical evaluation of endovascular procedures currently under investigation.

Aged↗
PubMed1996

[Surgical myocardial revascularization during the 1st 15 days of evolution of acute myocardial infarction].

Revascularization significantly improves early and late prognosis in acute myocardial infarction and has prompted substantial changes in therapeutic stategies. We report 140 patients aged 60.3 years old (123 male) operated within 15 days of sustaining an acute myocardial infarction, between January 1984 and December 1989. Coronary angiogram showed single vessel disease in 8 (6%), double vessel disease in 32 (23%), triple vessel disease in 85 (61%) and left main vessel disease in 13 (9%). Indications for surgery were postinfarction angina in 92 patients (66%), multiple severe coronary stenoses in 18 (13%), infarction of less than six hours from onset in 16 (11%), acute angioplasty failure in 7 (5%) and cardiogenic shock in 7 (5%). Thirty one patients were operated during the initial 24 h of infarction (16 with less than 6 h), 14 between the second and third day and 95 between the fourth and fifteenth day. Overall mortality was 4.3% (6/140). Among patients with failed angioplasty and cardiogenic shock, mortality was 23% (7/140), among patients with postinfarction angina this figure was 2.1% (2/92). No patient operated within 6 hours of infarction onset or due to severe coronary stenosis, died. Ninety seven percent of patients were followed during mean of 49 months. Three patients had a new acute myocardial infarction, two had sudden death and two died of unrelated causes. One required angioplasty and none was reoperated. Five years actuarial survival was 95% and the actuarial probability of being free of acute myocardial infarction, angioplasty or reoperation at five years was 99 and 100% respectively. It is concluded that early surgical revascularization in cute myocardial infarction is safe and has excellent long term results.

Adult↗
PubMed1995

[Retrograde cerebral perfusion during circulatory arrest with deep hypothermia. A new technique for brain protection in surgery of ascending aorta and aortic arch].

Between May 1993 and August 1994, 15 patients (10 men) with type A aortic dissection (9 acute) had a replacement of the ascending aorta and/or aortic arch with circulatory arrest with profound hypothermia and retrograde cerebral perfusion. Mean circulatory arrest time was 47.5 min (range 23 to 68 min). Three patients (20%) died in relation to postoperative bleeding. No patient had a new neurologic damage related to surgery. Ten patients were awake and oriented before 24 hours of the operation and another one before 48 hours; 4 patients required more than 48 hours to be completely awake and oriented. Two patients were operated on with a recent stroke. One of them recovered without sequelae before hospital discharge and the other one had a major regression of his brain damage. Two other patients had emergency surgery because of cardiac tamponade and cardiogenic shock. Both of them had a satisfactory recovery. Six patients presented azotemia but only 2 of them needed dialysis. There was no case of Q wave infarction nor congestive heart failure in the perioperative period. Follow-up was 100% completed (12 patients) with a mean of 9.8 months (range 5 to 18 months). One patient died on the 10th postoperative month because of a late infectious process. Eight patients are in functional class I and 3 in II. Ten of them are back to their usual activities'. Although retrograde cerebral perfusion is a new surgical technique, it seems to be a very valuable complement for brain protection in ascending aorta and/or aortic arch surgery with circulatory arrest with profound hypothermia.

Aged↗
PubMed1993

[Surgery of acute mitral valve insufficiency].

Between January 1980 and December 1990, 16 patients with acute mitral insufficiency were operated on an emergency basis at our institution. They represented 1.8% of all mitral surgical cases. All of them were in acute pulmonary edema and 7 in cardiogenic shock. The etiology was ischemic in 6, degenerative in 4, infectious in 3, degenerative and infectious in 2 and traumatic in 1. The pathologic mechanism was chordal rupture in 8 patients (5 anterior) and papillary muscle rupture in the other 8 (5 posterior). A mitral valve replacement was performed in all cases. Two patients died and 7 had morbidity in the postoperative period. One patient died 6 months after surgery of congestive heart failure. Ten patients are in NYHA functional class I at a mean follow-up of 48.1 months. Acute mitral insufficiency has different etiologies and pathologic mechanisms. In spite of the severe clinical condition of these patients, mitral valve replacement has good immediate and long-term results.

Acute Disease↗
PubMed1992

[Dissection of the ascending aorta (type A): diagnostic aspects, surgical treatment and long-term follow-up].

Aortic replacement is the treatment of choice and improves the natural history of dissections involving the ascending aorta. Forty patients (23 male), aged 49.4 years, have been operated at the hospital Clínico de la Universidad Católica. Twenty six presented with acute dissections. Angiography conformed the dissection in 63.3% and computed axial tomography in 84.6% of patients; lately, transesophageal echocardiography has become the most sensitive diagnostic method. Twenty three patients (57.5%) were subjected to emergency operations and 17 to semielective procedures. In 24 patients (60%) ascending aorta was replaced and in 16 a composite graft was used. Operative mortality was 27.5%. Univariate analysis showed that the period in which the operation was performed and the presence of limb ischemia were the only independent predictors of operative mortality. Long term follow up was achieved in 26 patients (89.6%). Actuarial 5 year survival without considering operative mortality was 87.9%. It is concluded that patients with acute dissections involving the ascending aorta should be operated as soon as the imaging diagnosis is complete and, since this is a palliative procedure, a close follow up is required for early detection of complications.

Adult↗
PubMed1991

Anesthesia for elective cardioversion: a comparison of four anesthetic agents.

Elective cardioversion is a short procedure performed under general anesthesia for the treatment of cardiac dysrhythmias. Selection of the anesthetic agent is important, because a short duration of action and hemodynamic stability are required. Forty-four patients scheduled for elective cardioversion in the coronary care unit were studied prospectively. All patients were randomly assigned, according to the last digit of their clinical record number, to receive one of the four anesthetic agents studied: group 1, 12 patients who received 3 mg/kg of sodium thiopental; group 2, 10 patients who received 0.15 mg/kg of etomidate; group 3, 12 patients who received 1.5 mg/kg of propofol; and group 4, 10 patients who received 0.15 mg/kg of midazolam. All patients also received 1.5 micrograms/kg of fentanyl 3 minutes before induction. All four drugs provided satisfactory anesthesia for cardioversion and there were no major complications. Midazolam produced a more prolonged duration of effect and more interindividual variability. Propofol was associated with hypotension and a higher incidence of apnea, and its duration of action was similar to that of etomidate or thiopental. Etomidate produced myoclonus and pain on injection; however, it was the only agent that did not decrease arterial blood pressure. Thiopental reduced blood pressure but otherwise seemed an appropriate anesthetic for this procedure. In conclusion, all four anesthetic agents were acceptable for cardioversion, although their pharmacological differences suggest specific indications for individual patients.

Adult↗
PubMed1986

Changes in platelet beta-thromboglobulin, fibrinogen, albumin, 5-hydroxytryptamine, ATP, and ADP during and after surgery with extracorporeal circulation in man.

Surgery with extracorporeal circulation (ECC) is associated with transient alterations of platelet function whose pathogenic mechanisms are not completely understood. To define further the platelet abnormalities, we determined the changes in platelet content of several granule-associated substances during and after ECC in patients subjected to aortocoronary bypass surgery. Platelet beta-thromboglobulin (beta-TG) decreased to 79.8% of the preoperative level at the end of ECC (p less than 0.01) and, as expected, did not recover 1 hr after the end of surgery. Platelet fibrinogen and albumin decreased to 67.9% (p less than 0.01) and to 29.8% (p less than 0.01) of baseline, respectively. However, 1 hr after surgery, platelet fibrinogen rose to 92% and albumin to 55.5% of baseline, denoting that during the recovery from ECC, platelets incorporate some plasma proteins. During ECC, platelet 5-hydroxytryptamine (5-HT) and total ATP and ADP decreased to 50.8% (p less than 0.01), 63.2% (p less than 0.01), and 69.9% (p less than 0.01) of their respective preoperative values, indicating dense body release. One hour after surgery, ATP recovered to 83.8%, suggesting that previous depletion compromised also the metabolic pool of adenine nucleotides. In summary, Our results confirm and extend previous observations demonstrating alpha-granule release during ECC. Platelets undergoing ECC can incorporate plasma proteins as evidenced by the rapid increase of platelet fibrinogen and albumin after bypass. Although the mechanisms of this increase and site of storage of the exogenous substances are unknown, this observation justifies further studies to determine if internalization of plasma proteins, especially fibrinogen, may take place in physiological conditions. Dense body depletion with transient storage pool deficiency appears to be a component of the reduced platelet function during ECC. Consumption of metabolic ATP with alteration of platelet energy metabolism may further impair platelet function, contributing to the bleeding episodes observed during surgery with ECC.

Adenosine Diphosphate↗
PubMed1986

Disc dislodgment in Björk Shiley mitral valve prosthesis: two successfully operated cases.

Two patients with Björk Shiley mitral valve replacement had migration and embolization of the occluding disc. One patient suffered migration of the disc a few hours after surgery and the other had a strut fracture with disc translocation six years after the initial operation. Clinical signs in both cases were pulmonary edema, cardiogenic shock, and absence of prosthetic sounds. Both patients were reoperated on an emergency basis, recovering after a complicated postoperative course. They are on functional Class I, 8 and 1 years later, respectively, with their dislodged discs still in the abdominal aorta. The only hope for survival in these patients is emergency reoperation, once the prosthetic mitral valve dysfunction is confirmed.

Adult↗