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Biomedical subjects

M Córdoba

Publications and source records attributed to M Córdoba.

At least 19 recordsLinked to original sources
PubMed2006

Heparin and quercitin generate differential metabolic pathways that involve aminotransferases and LDH-X dehydrogenase in cryopreserved bovine spermatozoa.

Heparin and quercetin induce capacitation in spermatozoa through membrane receptor binding and inhibition of Ca-ATPase of the plasma membrane, respectively. Although capacitation is energy intensive, ammonia from amino acid metabolism can inhibit respiration and Krebs cycle activity. The objective was to determine activities of key enzymes in bull spermatozoa that contribute to the redox state and supply energy for capacitation. Malate dehydrogenase (MDH-NAD(+)), alanine and aspartate aminotransferases (ALT, AST), and lactate dehydrogenase-X (LDH-X) were measured spectrophotometrically (340 nm); mean (+/-S.D.) activities in control spermatozoa were 7.65+/-1.67, 0.45+/-0.05 and 0.74+/-0.14x10(-2)U/10(8) spermatozoa for MDH-NAD(+), ALT and AST, respectively, and were 2.83+/-0.66U/10(8) spermatozoa for LDH-X. Heparin decreased (P<0.05) activities of MDH-NAD(+), ALT, AST and LDH-X (78, 53, 66 and 66% of control levels, respectively); we inferred that amino acid catabolism was decreased. Quercetin decreased (P<0.05) activities of MDH-NAD(+) and ALT (60 and 49% of control levels), but activities of AST and LDH-X were not significantly different from controls; apparently maintenance of LDH-X activity supplied pyruvate for cellular metabolism. The proportion of capacitated spermatozoa in controls (8.5+/-1.73%) was substantially increased (P<0.05) by treatment with either heparin (36.2+/-4.5%) or quercetin (32.8+/-4.7%), there was no significant difference among groups for acrosomal integrity and sperm viability. In conclusion, heparin- or quercetin-induced capacitation affected different metabolic pathways that modulated the redox state and oxidative metabolism in cryopreserved bovine spermatozoa.

Animals↗
PubMed2005

Respiratory burst and NAD(P)H oxidase activity are involved in capacitation of cryopreserved bovine spermatozoa.

Heparin (a glycosaminoglycan) and quercetin (a calcium-ATPase plasma membrane specific inhibitor) induce bovine sperm capacitation. Mitochondria from frozen semen are capable of generating oxidative energy. The aim of the study was to determine oxygen uptake variation and the participation of diphenileneiodonium (DPI)-sensitive oxidases from spermatozoa capacitated with heparin or quercetin. Oxygen uptake was measured polarographically and 2 microM diphenileneiodonium (DPI) was used as a specific inhibitor of NAD(P)H-oxidases. Sperm capacitation was determined by the chlorotetracycline technique. Heparin produced a respiratory burst (17.0+/-3.2 microL O2/h/10(8) spermatozoa; mean+/-S.D.) versus control (11.3+/-0.9 microL O2/h/10(8) spermatozoa; P<0.05). Oxygen uptake and sperm hypermotility were inhibited by cyanide. Treatment with DPI blocked heparin capacitation and oxygen uptake (cyanide-sensitive) decreased to control levels. Respiration of quercetin-treated samples (cyanide-sensitive; 9.7+/-0.7 microL O2/h/10(8) spermatozoa) was not significantly different from the controls; oxygen uptake was not modified by DPI, but quercetin capacitation was inhibited (P<0.05). The effect of DPI with heparin confirmed that oxidases participate in capacitation induction. The addition of superoxide dismutase and/or catalase to heparin- or quercetin-treated samples, failed to modify oxygen uptake and blocked capacitation (P<0.05), suggesting that the superoxide anion (O2*-) participates in the capacitation induction. High mitochondrial activity from heparin-treated samples indicated that energy requirements, especially for hypermotility, were supported by the respiratory chain. Although a respiratory burst was not produced by quercetin, DPI-sensitive-oxidases (O2*- source) were necessary for capacitation. In cryopreserved bovine spermatozoa, heparin- or quercetin-induced capacitation required different levels of mitochondrial energy and DPI-sensitive oxidase activity.

Animals↗
PubMed2005

[Improvements in lung preservation: 3 years' experience with a low-potassium dextran solution].

OBJECTIVE: Lung preservation quality is a crucial factor in the success of a lung transplant. In October 2000 we stopped using Euro-Collins (EC) lung preservation solution and began using a low potassium dextran solution (Perfadex [PER]). The objective of the present study was to assess outcome with the 2 solutions. MATERIAL AND METHODS: We analyzed the results of 68 lung transplants in which PER was used and compared the results with those of a historical control group consisting of the same number of transplants in which EC was used. RESULTS: There were no significant differences in the ages and diagnoses of the recipients in the 2 groups. Waiting list time was longer in the PER group. The most frequent cause of donor death in the EC group was craniocerebral trauma (62%), whereas in the PER group it was cerebral hemorrhage (54%). In the PER group more double lung transplants were performed than in the EC group (78% and 53% respectively; P=.002). There were no differences in the use of extracorporal circulation or ischemia time between the 2 groups. Early graft function, based on the patient's oxygenation index (ratio of PaO2 to inspired oxygen fraction [FiO2]) on arrival at the intensive care unit, was similar in the 2 groups. The incidence of severe graft failure (PaO2/FiO2<150 mm Hg) was significantly lower in the PER group than in the EC group (16% and 37% respectively; P=.01). No significant differences in hours of mechanical ventilation or postoperative mortality between the 2 patient series were found. CONCLUSIONS: Use of the newer lung preservation solution --PER-- led to a 50% lower incidence of severe ischemia-reperfusion graft injury during the early recovery from lung transplantation.

Adolescent↗
PubMed2005

Differential activities of malate and isocitrate NAD(P)-dependent dehydrogenases are involved in the induction of capacitation and acrosome reaction in cryopreserved bovine spermatozoa.

Sperm catabolic processes produce energy for capacitation and acrosome reaction induction required for oocyte fertilization. The aim was to determine metabolic enzymes' activities and their participation in the supply of energy and generation of the redox state to acquire fertilizing capacity. Capacitation was induced with heparin and quercetin, and the acrosome reaction with progesterone. Enzymatic activities were determined spectrophotometrically. The chlortetracycline and differential-interferential contrast microscopy/tryptan blue techniques were used to evaluate capacitation and acrosome reaction, acrosomal integrity and sperm viability respectively. A 2 : 1 and 3 : 1 ratio were obtained for isocitrate dehydrogenase (IDH)-NADP/NAD and malate dehydrogenase (MDH)-NADP/NAD activities respectively. MDH-NADP activity remained constant with different treatments, unlike MDH-NAD activity, which diminished with both capacitation inducers and in acrosome-reacted spermatozoa previously treated with heparin (P < 0.05). IDH-NADP decreased its activity 50% in spermatozoa capacitated with heparin and acrosome reacted with progesterone (P < 0.05). Capacitation and acrosome reaction processes induced with heparin and progesterone, respectively, involve a differential oxidative metabolism, with the participation of MDH-NAD(P) and IDH-NAD(P) enzymes, whose activities would be linked to the malate-aspartate, lactate-pyruvate and isocitrate cytosolic-mitochondrial shuttles. These enzymes play a major role in supplying reduction equivalents and/or energy required for capacitation and acrosome reaction in cryopreserved bovine spermatozoa.

Acrosome Reaction↗
PubMed2004

Proacrosin-acrosin activity in capacitated and acrosome reacted sperm from cryopreserved bovine semen.

Acrosin activity is associated with normal fertility in human and bovine spermatozoa. The aim of the study was to determine the variation of the enzyme activity in the proacrosin-acrosin system in capacitated and acrosome reacted cryopreserved bovine sperm. Enzyme activity was assessed spectrophotometrically using N-alpha-benzoyl-DL-arginine p-nitroanilide (BAPNA) as specific substrate for acrosin at pH 8. Capacitation with heparin and quercitin failed to induce conversion of proacrosin to acrosin. An increase in acrosin activity produced by the presence of progesterone, in a dose-dependent manner, was related with the induction of true acrosome reaction. The total level of acrosin activity registered showed that 96% of acrosin of capacitated sperm samples and control is present in the zymogen form. Moreover, progesterone is capable of duplicating the level of active enzyme, indicating that enzyme activity changes are related to acrosome reaction, suggesting that only a minor proportion of the total of proacrosin-acrosin system is required in the exocytotic process on cryopreserved bovine sperm.

Acrosin↗
PubMed2001

Progesterone effect mediated by the voltage-dependent calcium channel and protein kinase C on noncapacitated cryopreserved bovine spermatozoa.

An increase in intracellular calcium is essential to trigger capacitation and the acrosome reaction. The aim of this study was to determine the progesterone effect mediated by the voltage-dependent calcium channel and protein kinase C on heparin-capacitated and noncapacitated spermatozoa. Protein kinase C was activated by 1-oleoyl-2-acetyl glycerol, a membrane-permeant diacyl-glycerol, and inhibited by GF-109203X. The percentage of true acrosome reaction was evaluated using differential-interferential optical contrast microscopy and trypan blue stain. The calcium concentration was evaluated by FURA-2AM and methoxyverapamil was used as a voltage-dependent calcium channel inhibitor. A rapid calcium increase and acrosome reaction were induced by progesterone in capacitated and noncapacitated spermatozoa, a higher intracellular calcium increase being observed in capacitated than in noncapacitated samples (P < 0.05). The calcium increase and acrosome reaction were blocked significantly by GF-109203X in noncapacitated and capacitated spermatozoa by the addition of progesterone and/or 1-oleoyl-2-acetylglycerol. Methoxyverapamil blocked calcium influx in samples treated with progesterone and heparin/progesterone, but not in those treated with 1-oleoyl-2-acetyl glycerol. Progesterone induces the acrosome reaction in noncapacitated cryopreserved bovine spermatozoa through intracellular mechanisms dependent on protein kinase C and the voltage-dependent calcium channel.

Animals↗
PubMed1997

[Factors related to the appearance of peripheral vascular complications after taneous cardiovascular interventions].

BACKGROUND: Percutaneous diagnostic and therapeutic cardiac catheterization procedures carries some risks, most of them related to the appearance of peripheral vascular complications. These complications imply additional treatments for the patient including vascular surgery, longer hospital stays and increased costs. Some clinical and procedural variables have been pointed out as independent predictors of appearance of vascular complications. Nevertheless, no information have been reported concerning to the influence of the experience of the cardiologist who performs the procedure or provides the local hemostasia and the rate of vascular complications. OBJECTIVE: To characterise the type and incidence of peripheral vascular complications in patients undergoing a percutaneous cardiac procedure, to identify the predictors and to determine the influence of the professional experience and the complexity of the technique in the complications rate. METHODS AND RESULTS: Within 1-year (1994 to 1995) period, 1,008 consecutive patients undergoing a percutaneous cardiovascular procedure (750 diagnostic and 258 therapeutic) were prospectively included. Seventy percent were male. Mean age was 63 +/- 2 years. A total of 55 vascular complications were demonstrated (5.6%): 36 (3.6%) hematomas, 14 (1.4%) pseudoaneurysms, 2 (0.2%) arteriovenous fistula, 2 (0.2%) episodes of limb ischemia and 1 (0.1%) retroperitoneal hematoma. Only 28 (2.8%) were severe complications. By multivariate analysis, only experience to perform hemostasis (OR: 3.36; 95% CI: 1.37-8.22), previous treatment with aspirin (OR: 2.69; 95% IC: 1.31-5.52), left femoral artery puncture (OR: 2.53; 95% IC: 1-1.02), sheath removal later than 60 minutes (OR: 1.02; 95% IC: 1.01-1.04) and hemostasis which lasted > 30 minutes (OR: 1.01; 95% IC: 1-1.02), were independent predictors of vascular complications. CONCLUSIONS: Vascular complications rate after percutaneous cardiovascular procedures was low. Most of them associated to procedural variables and potentially avoidable, with promotion of a well planned policy of training in order to modify the factors involved.

Aged↗
PubMed1997

Intracellular calcium variation in heparin-capacitated bovine sperm.

This report investigates the mechanisms by which heparin induces capacitation of sperm. Capacitation was determined with chlortetracycline and intracellular calcium concentration, [Ca2+]i, with FURA 2-AM. After 15 minutes incubation with heparin [Ca2+]i was increased 60% over basal, reaching a plateau thereafter. Sixty percent of calcium entry was inhibited by methoxy-verapamil, suggesting that activation of voltage dependent calcium channels (VDCC) may be involved in the process. A significant correlation (R1 = 0.88, p < 0.006) was found between the percentage of capacitated spermatozoa and the [Ca2+]i increase. The effects of heparin on both processes were blocked by the protein kinase C (PKC) inhibitors staurosporine (100%) and GF-109203X (90%). It is concluded that heparin may induce sperm capacitation and calcium influx mainly through VDCC (approx. 60%), and also through other membrane systems (40%). Both systems of calcium entry as well as the capacitation process appear to involve on PKC activity.

Animals↗
PubMed1997

Improved distribution of pulmonary flush solution to the tracheobronchial wall in pulmonary transplantation.

This report describes the experimental results obtained with conventional (pulmonary artery, PA) flushing versus retrograde perfusion (via left atrium, LA) using 99mTc-labeled macroaggregated albumin (MAA-99mTc) to ascertain the distribution throughout the tracheobronchial (TB) tree in 10 Large-White pigs. Lung preservation was achieved with 4 degrees C Euro-Collins solution (60 ml/kg) instilled via PA (n = 5) or LA (n = 5). Simultaneously, MAA-99mTc was given using the same respective route and the isotope uptake quantified at different TB levels after heart-lung block harvest and dissection of all tissue adjacent to TB: proximal and distal trachea and right and left main bronchi. Retrograde distribution resulted in a significantly higher 99mTc count compared to the PA route (p < 0.01).

Animals↗
PubMed1996

Clinical experience with retrograde lung preservation.

Previous reports and our own experimental work suggest increased vascularity of the tracheobronchial wall when retrograde lung preservation is used. This principle was clinically applied in 21 consecutive lung transplant recipients (10 single and 11 bilateral). Lung preservation was achieved via the left atrial appendage and drainage was obtained through the pulmonary artery. Pneumoplegic preservation was achieved with modified Euro-Collins solution. Cardioplegia was induced by the standard method and the heart, harvested by different teams, did not exhibit left ventricular dilatation. Thirty-two bronchial anastomoses without wrapping were performed. No primary lung graft failure was documented. Cardiopulmonary bypass was instituted in three cases of pulmonary hypertension; however, this was deemed unnecessary in the remainder of the cases of bilateral transplantation while the second organ was being implanted. All bronchial anastomoses were followed between 2 and 28 months. A single instance of bronchial anastomosis dehiscence was observed on the 30th postoperative day. However, no stents were employed in this series, and no strictures or anastomotic granulomas have been reported so far. All the hearts could be used satisfactorily except for one primary graft failure. In conclusion, retrograde lung preservation is feasible in clinical lung transplantation, with simultaneous harvesting of the heart. The impact of retrograde lung preservation on the late clinical outcome remains to be seen.

Anastomosis, Surgical↗
PubMed1996

Gangliosides minimize motor disabilities and histopathological changes in cortical lesioned and transplanted rats.

The effect of bovine brain gangliosides was studied in rats lesioned by partial suction of the right somatosensory cortex and also in rats implanted with a piece of fetal brain tissue in this area. In both experiments a group of animals received 30 mg/kg i.p. of gangliosides daily for a period of 7 days after surgery. In lesioned rats, the untreated group showed a lower maintenance on a tight rope test at 7 as well as at 14 days, as compared with a sham-operated group (p < 0.05). In transplanted rats ganglioside treatment prevented the increase of the probability of falls from a horizontal bar at days 7 and 14 post-operations and the probability of slips on a vertical bar at day 7 (p < 0.05). Rats were killed at day 15 and brain coronal sections were obtained. Nuclear area and circularity were measured in a sample of cortical and grafted cells in a computer aid-image analyzer. Ganglioside protection on the normal size and shape of the nuclei in the ipsilateral cortex in lesioned as well as in transplanted rats (p < 0.01) was found. A higher nuclear area in ganglioside than in saline treated grafts was noted. Results suggest a protective action of the gangliosides against the lesion-induced motor dysfunction and secondary cortical cell degeneration.

Animals↗
PubMed1995

Mitochondrial calcium uptake in bovine frozen sperm.

Mitochondria from bovine frozen semen are capable of preserving oxidative energy. The purpose of this work was to study calcium uptake by the inner mitochondrial membrane which, together with the plasmatic membrane, is involved in spermatic motility and viability regulation. Mitochondrial coupling was confirmed. In the active state, there was a drop in oxygen uptake rate using calcium concentrations ranging from 20 to 100 microM. In the resting state, 75 microM calcium concentration mimicked the active respiration state. In both states, concentrations greater than 100 microM induced mitochondrial uncoupling. Maximal mitochondrial uptake was recorded in the active state with 10 microM lactate. At calcium concentrations greater than 100 microM, there was a drop in mitochondrial calcium uptake for both respiration states. The ability to preserve oxidative energy allows the spermatozoon to take up mitochondrial calcium, thus regulating its functional activity.

Adenosine Diphosphate↗
PubMed1984

Relation of midwall circumferential systolic stress to equatorial midwall fibre shortening in chronic aortic regurgitation. Value as a predictor of postoperative outcome.

Nineteen patients with chronic aortic regurgitation and a large increase in heart size were studied before aortic valve replacement. By relating midwall circumferential systolic stress to midwall circumferential fibre shortening (Cs/Cd) before operation the patients could be divided into two well defined groups. Twelve patients (group 1) had a pronounced decrease in heart size as measured by the cardiothoracic ratio and an excellent clinical outcome six months after operation. Seven patients (group 2) had no significant decrease in heart size and a less good clinical outcome. The ratio of midwall circumferential systolic stress to end systolic volume index was significantly higher in group 1 than in group 2. Group 2 had more severe left ventricular hypertrophy determined by the ratio of the wall thickness to the minor internal radius of the left ventricle (h:r ratio), total left ventricular mass, and left ventricular mass to end diastolic volume ratio. There were no significant differences in any other haemodynamic or angiographic indices between the two groups. Thus the relation of midwall circumferential systolic stress to fibre shortening is useful in determining the prognosis in individual patients with chronic aortic regurgitation undergoing aortic valve replacement.

Adult↗
PubMed1983

Early in vivo hemodynamic evaluation of the mitral Medtronic-Hall cardiac valve.

We studied the hemodynamics of 14 patients with a Medtronic-Hall prosthesis in mitral position 6 months after valve implantation. The usual hemodynamic parameters showed a striking improvement after surgery. The mean pulmonary arterial pressure decreased from (mean +/- SD) 37 +/- 10.7 mmHg to 20 +/- 6.5 mmHg (p less than 0.005). Mean pulmonary capillary pressure decreased from 24 +/- 7.1 mmHg to 10 +/- 3.0 mmHg (p less than 0.001). Cardiac output increased slightly from 3.7 +/- 0.8 L/min to 4.2 +/- 0.45 L/min, the difference not being significant. Valvular area at rest was 1.82 +/- 0.25 cm2 and increased significantly during exercise to 2.47 +/- 0.45 cm2 (p less than 0.001). The opening angle of the disk occluder reached a mean value of 64 +/- 4.6 degrees, that is 91% of the maximal theoretical opening angle. We fitted a hydraulic function gradient = Ax (Flow)n (mean r = 0.9176), to the paired data of gradient and flow obtained during progressive exercise. This procedure permitted us to establish the actual hemodynamic behavior of the prostheses which did not concur with the behavior predicted by the Gorlin formula. We conclude that the Medtronic-Hall mitral prosthesis is an acceptable alternative when mitral valve replacement is considered.

Adult↗