PubMed Health⌕ Search

Biomedical subjects

J R Berrazueta

Publications and source records attributed to J R Berrazueta.

At least 19 recordsLinked to original sources
PubMed2006

Ischemic preconditioning and kidney transplantation: in vivo nitric oxide monitoring in a rat ischemia-reperfusion experimental model.

Direct nitric oxide measurement in live tissue would help us to understand its role in ischemia-reperfusion injury and its relationship to ischemic preconditioning (IP). We constructed four experimental groups of ischemia-reperfusion in the rat kidney: G1 were controls; G2, 1 hour of renal ischemia; G3 and G4: one or two 15/10 minute cycles, respectively, of IP prior to 1 hour of ischemia. Real-time in vivo nitric oxide measurements were compared with functional parameters of kidney damage at 24 hours. The peaks of nitric oxide production in the IP periods increased less in the rising curve of nitric oxide production during the 1 hour ischemia time. No improvement in the IP groups was observed based on serum creatinine levels at 24 hours.

Animals↗
PubMed2003

Autoantibodies against oxidized LDL and serum total antioxidant status in active cyclists and ex-cyclists.

There is an apparent paradox between the benefits of aerobic exercise and the potentially deleterious effects of increased free radicals and decreased circulating antioxidants generated during exercise. To assess the oxidative/antioxidative status in competitive cyclists and ex-cyclists, we measured two markers not well studied in these situations, serum total antioxidant status (TAS) and antibodies against oxidized LDL (AuAb-ox-LDL) in 18 competitive male cyclists, 10 ex-competitive cyclists and 14 healthy males. AuAb-ox-LDL was evaluated by enzyme immunoassay, and serum TAS concentration was analyzed by spectrophotometry. Ex-cyclists had serum TAS levels statistically higher than the control group and cyclists group (p = 0.001 and p < 0.001, respectively). Active sportsmen showed significantly less AuAb-ox-LDL than healthy sedentary males, while there was a non-significant trend in the ex-cyclists to have lower AuAb-ox-LDL than the corresponding control group. AuAb-ox-LDL levels were not statistically different between the groups of active and previously active sporting men. There was a positive correlation between TAS and LDL-cholesterol in active cyclists under heavy training. In the ex-cyclist group, there was a negative correlation between serum TAS and the time elapsed since they had ended the competition. Competitive cycling decreases AuAb-ox-LDL levels, suggesting that it may decrease ox-LDL levels. After ending physical training, antioxidative status remains increased for at least one year, but the effect on AuAb-ox-LDL levels is lost.

Adolescent↗
PubMed2001

Venous endothelial function in postmenopausal women after six months of tibolone therapy.

STUDY OBJECTIVE: To test venous endothelial function in long-term climateric therapy with tibolone. DESIGN: Measurement of dorsal hand-vein diameter by venous occlusion plethysmography during infusion of norepinephrine (NE), bradykinin (BK), NG-monomethyl L-arginine (L-NMMA) and sodium nitroprusside (SNP). SETTING: Plethysmography and Menopause Units. University Hospital Valdecilla. Santander. Spain. PATIENTS: Eleven postmenopausal women having continuous treatment with oral tibolone (2.5 mg/day) for 6 months. INTERVENTIONS: Three plethysmography studies were made: at baseline, and at three and six months of treatment. MAIN OUTCOME MEASURES: Dorsal hand-vein diameter measured by venous occlusion plethysmography during infusion of NE, BK, L-NMMA and SNP. RESULTS: (a) Baseline study: maximum dilation with BK was 54.2+/-10.2%. (b) Three-month study: BK dilation of 71.5+/-11.9%, with a significant increase of 17.3% (P=0.019) compared with baseline. (c) Six-month study: BK dilation of 77.5+/-11.9%, with a significant increase 23.3% (P=0.002) compared with baseline. Maximal vasodilation was reached with SNP in the three studies and L-NMMA infusion has a similar vasoconstrictor response in the three studies. CONCLUSIONS: Long-term climateric therapy with tibolone improves vein endothelium-dependent vasodilation suggesting a positive impact of this drug on endothelial function.

Administration, Oral↗
PubMed1998

Effects of radiation on endothelial function.

PURPOSE: The response of endothelium to ionizing radiation was studied. METHODS AND MATERIALS: The abdominal aorta in different experimental groups of rats was irradiated, and the response of arterial rings from the irradiated segments to norepinephrine, acetylcholine (ACh), and nitroglycerin (NTG) was studied. Nonirradiated thoracic segments in the same experimental animals were used as as a control for comparisons. Two age-matched nonirradiated control groups were also studied. RESULTS: A poor endothelium-dependent vasodilator response was obtained with ACh in the irradiated rings and also in those not directly irradiated; the endothelium-independent vasodilator response to NTG was preserved during the first 3 days after irradiation. By 6 months, both the endothelium-dependent response and endothelium-independent response were impaired. CONCLUSIONS: Alterations in nitric oxide synthesis and/or release by the endothelium were observed during the early phase of radiation in irradiated and nonirradiated segments. In the delayed phase of radiation, endothelium-independent muscular relaxation was also affected.

Acetylcholine↗
PubMed1998

Age-related responses of vasoactive factors during acute exercise.

To evaluate the age-related response of vasoactive factors during acute exercise, young (n = 8, aged 23.6+/-2 years) and old (n = 13, aged 77+/-6 years) healthy volunteers performed a stress test using a treadmill, and blood samples were taken before and after exercise. There were neither basal (old people 77+/-53 vs. young people 67.6+/-40 pg/ml) nor peak exercise-related (old people 77+/-43 vs. young people 66.8+/-34 pg/ml) differences in plasma adrenomedullin (AM) between both groups. AM did not increase with exercise in either group. Regarding plasma cAMP, there were neither basal nor exercise related differences, but this nucleotide increased with exercise in both groups (old people p < 0.0001, young people p < 0.05). Plasma Atrial Natriuretic Peptide (ANP) was higher in basal (116.3+/-64 vs. 46.8+/-21 pg/ml, p < 0.003) and after exercise samples (150.2+/-76.5 vs. 68.7+/-29.5 pg/ml, p < 0.004) in old people as compared with young people. Old people showed an increase in ANP with exercise (p < 0.05), but in young people, though there was a trend to increase, it did not reach statistical significance. There were neither basal nor exercise related differences in plasma cGMP, but this nucleotide increased with exercise in both groups. Angiotensin II (AT-II) levels were lower in basal and after exercise samples in old people as compared with young people. AT-II levels did not increase with exercise in either group. These data suggest that, with increasing age, the vascular tree develops resistance to ANP and higher sensitivity to AT-II, while AM levels do not change. Exercise makes ANP changes more evident, while AM and AT-II are not modified.

Adrenomedullin↗
PubMed1998

Plasma adrenomedullin levels in type 1 diabetes. Relationship with clinical parameters.

OBJECTIVE: To assess the relationship between plasma adrenomedullin (AM) levels and the presence of microvascular complications in type 1 diabetic patients. RESEARCH DESIGN AND METHODS: We measured plasma AM and cAMP levels in 103 type 1 diabetic patients (46 without complications, 24 with retinopathy only, 14 with microalbuminuria but normal kidney function, and 19 with renal insufficiency) and 41 matched healthy control subjects. RESULTS: Patients with renal insufficiency had higher levels of AM and cAMP than all other groups. Patients with only retinopathy showed a trend to have higher levels than patients without complications. There were no differences among all other groups. There was a significant correlation between AM and cAMP in the total diabetic group (rs = 0.36, P < 0.001) but not in the control group. In multiple regression analysis, plasma AM demonstrated significant relationships with creatinine clearance (beta = -0.31, P = 0.004) and duration of the disease (beta = 0.28, P = 0.008). CONCLUSIONS: Plasma AM and cAMP are increased in type 1 diabetic patients with renal insufficiency. Creatinine clearance (CrClc) and duration of the disease are related to plasma AM levels in these patients.

Adrenomedullin↗
PubMed1997

Dose- and time-dependency of the dilator effects of the endothelin antagonist, BQ-123, in the human forearm.

AIMS: Endothelin-1 is a potent endogenous vasoconstrictor that acts on the endothelin A (ET[A]) receptor. The dose-response and time-course of the dilator effect of the ET(A) receptor antagonist, BQ-123, was investigated in the forearm of healthy volunteers. METHODS: Forearm blood flow was measured using mercury-in rubber strain gauge venous occlusion plethysmography. RESULTS: Following intra-arterial infusion of BQ-123 (50 nmol min-1) for 5 min, forearm blood flow increased by approximately 60% over the next 60 minutes; lower doses were without significant effect. The degree of dilatation was similar to that observed in previous studies using 20-fold larger doses. CONCLUSIONS: This study confirms that basal endothelin-1 has a role in the physiological regulation of vascular tone. It is possible that at low doses, BQ-123 might be a more sensitive pharmacological tool for the detection of abnormal endothelin-1 mediated constriction.

Adult↗
PubMed1997

Contribution of nitric oxide to exercise-induced changes in healthy volunteers: effects of acute exercise and long-term physical training.

Endothelium plays a central role in the regulation of regional blood flow through the release of certain vasoactive substances. We conducted this study to test whether an increase in the production of nitric oxide (NO) metabolites, atrial natriuretic peptide (ANP) and plasma and intraplatelet cyclic guanosine 3':5' monophosphate (cGMP) is involved in the adaptation to chronic exercise in physically trained people and in the vasodilatation induced by acute physical exercise. We studied one group of 10 trained athletes and another group of 10 untrained people. We measured plasma levels of nitrites, nitrates and cGMP and intraplatelet levels of cGMP, as an indicator of intracellular guanylate cyclase activity, and ANP before and after a maximal treadmill test. Resting cardiac rate (CR) and systolic blood pressure (SBP) were lower in the athlete group than in the control group (73.8 +/- 3.6 vs. 92 +/- 5.9; P < 0.02 and 110 +/- 2.58 vs. 118 +/- 3.27; P < 0.02 respectively). SBP did not show differences between groups after the exercise test. Diastolic blood pressure (DBP) at rest was lower in the athlete group (71 +/- 1.79 vs. 80.5 +/- 3.53; P < 0.03) and the decrease after maximal exercise was more pronounced in this group (64 +/- 2.67 vs. 74.5 +/- 3.2; P < 0.02). Basal plasma nitrites were 4.9 +/- 0.8 in the athlete group and 1.9 +/- 0.3 in the control group (P < 0.05). After exercise, test differences between groups remained (P < 0.05). Nitrates were significantly higher in the group of athletes and did not show exercise-related changes. Plasma levels of cGMP and ANP increased in both groups after the treadmill test, with no differences between groups. Among the athletes, cGMP increased from 1.11 +/- 0.1 to 2.6 +/- 0.4 (P < 0.001), whereas in the untrained group plasma cGMP rose from 1.14 +/- 0.09 to 1.86 +/- 0.2 (P < 0.01). There was a significant correlation between the increases in plasma cGMP and the atrial natriuretic peptide in both groups (r = 0.91, P < 0.0002, for athletes; and r= 0.68, P < 0.04, for control group). The intraplatelet concentration of cGMP did not show differences between groups and did not change after exercise. In conclusion, we have found increased basal levels of plasma nitrite and nitrate in trained subjects. Exercise does not produce differences in the increments of these metabolites. Therefore, we speculate the release of nitric oxide is not augmented by exercise in trained athletes.

Adult↗
PubMed1996

Regression of lupus endocarditis after treatment of an arteriovenous fistula.

A young woman with systemic lupus erythematosus (SLE) and antiphospholipid antibodies was referred to our Cardiology Department. She had a large vegetation on the mitral valve, along with significant mitral regurgitation, pulmonary hypertension and slight signs of heart failure on physical examination and chest X-ray. A previously undetected iatrogenic arteriovenous fistula was surgically corrected, with subsequent normalization of pulmonary arterial pressure. Surprisingly, the mitral valve recovered a normal appearance in 21 days. We interpret the hemodynamic disturbances as a consequence of the high-output situation created by the fistula, and the regression of the vegetation as the lysis of a thrombus versus a silent embolism.

Adult↗
PubMed1996

Nitric oxide production during the hyperacute vascular rejection.

A complete understanding of the biological mechanisms that take part in the hyperacute vascular rejection is necessary to prevent its development. Nitric Oxide (NO) release by the graft could be one of those mechanisms as cytokine induction of NO synthase in reticuloendothelial cells produces NO with cytotoxic activity. We have performed 20 heterotopic pig-to-dog kidney xenotransplantations in order to determine if cytotoxic NO is released during the hyperacute rejection. Nitrites and cGMP levels were determined in plasma samples taken from the graft artery and vein until vessel thromboses. NO synthase activity was measured in pieces from renal artery and renal tissue. The results show that after discordant xenotransplantation, inducible NO synthase is activated in the transplanted organ, indicating that NO can mediate host tissue damage during the hyperacute rejection.

Acute Disease↗
PubMed1996

Tricuspid valve replacement in rheumatic disease: preoperative predictors of hospital mortality.

BACKGROUND AND AIM OF THE STUDY: The study analyzes the possible predictive power of different clinical and hemodynamic parameters with regard to hospital mortality after the first tricuspid valve replacement. METHODS: A retrospective study of 62 consecutive patients undergoing tricuspid valve replacement from 1974 to 1994 (7.2% of all tricuspid surgery performed at our institution in this period) was completed. Hospital mortality was 37%. Twenty-three patients died in hospital after the first tricuspid valve replacement (group I) and 39 patients (group II) survived this procedure. Tricuspid insufficiency was organic in 87% of group I and 84.6% of group II. RESULTS: The parameters showing significant differences between the two groups were NYHA class IV (p = 0.05), severe congestive heart failure (p = 0.02), mean right atrial pressure (p = 0.05), pulmonary arterial resistance (p = 0.006) and mean pulmonary arterial pressure (p = 0.0001). Cardiopulmonary bypass time (p = 0.005) and aortic cross-clamp time (p = 0.05) were longer in group I. Multiple regression analysis showed that the variables with greatest predictive power for hospital death were preoperative functional class, congestive heart failure and mean pulmonary artery pressure. The model gave a p < 0.001, with r = 0.58. CONCLUSIONS: The high hospital mortality rate after tricuspid valve replacement seems to be related to clinical functional class, severe congestive heart failure, and to chronic hemodynamic changes in the right atrium and pulmonary circulation.

Adult↗
PubMed1995

Effect of isosorbide-5-mononitrate on plasma and urine levels of cyclic GMP in relation to exercise in coronary patients compared with control subjects.

Nitric oxide (NO) and atrial natriuretic peptide (ANP) relax vascular smooth muscle increasing levels of cyclic guanosine 3':5' monophosphate (cGMP). Nitrovasodilators act as exogenous nitric oxide donors. The aim of this study was to ascertain the response of cGMP to exercise without medication and after the administration of 20 mg of isosorbide-5-mononitrate (IS-5-MN) in coronary patients (n = 8) and healthy control subjects (n = 9). A third group of 10 normal volunteers was studied to test plasma cGMP response to second exercise test without IS-5-MN administration. Plasma cGMP increased significantly in both patients (P < 0.02) and controls (P < 0.01) after the first ergometry. After IS-5-MN administration, plasma cGMP did not increase either before or after exercise. In normal volunteers without IS-5-MN plasma cGMP increased significantly after first (P < 0.004) and second (P < 0.0008) exercise test. In conclusion, plasma cGMP increases during exercise. Administration of IS-5-MN does not raise plasma cGMP and neither does performance of further exercise after its administration.

Angina Pectoris↗
PubMed1994

Induction of nitric oxide synthase in human mammary arteries in vitro.

This study investigated whether human mammary arteries express an inducible nitric oxide (NO) synthase and, if so, what its effects are on vascular tone. In human mammary artery pre-contracted with phenylephrine there was a gradual time-dependent loss of tone over an 8 h period. L-Arginine and lipopolysaccharide enhanced the rate but not the magnitude of this loss in tone, whereas NG-nitro-L-arginine, NG-monomethyl-L-arginine, dexamethasone, and polymyxin B inhibited these effects. These findings indicate that incubation of human mammary artery with lipopolysaccharide resulted in the expression of an inducible NO synthase. The induction of this enzyme in human vessels may be important in the pathogenesis of septic shock.

Amino Acid Oxidoreductases↗