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J G Martínez

Publications and source records attributed to J G Martínez.

14 recordsLinked to original sources
PubMed2006

A quantitative trait locus for recognition of foreign eggs in the host of a brood parasite.

Avian brood parasites reduce the reproductive output of their hosts and thereby select for defence mechanisms such as ejection of parasitic eggs. Such defence mechanisms simultaneously select for counter-defences in brood parasites, causing a coevolutionary arms race. Although coevolutionary models assume that defences and counter-defences are genetically influenced, this has never been demonstrated for brood parasites. Here, we give strong evidence for genetic differences between ejector and nonejectors, which could allow the study of such host defence at the genetic level, as well as studies of maintenance of genetic variation in defences. Briefly, we found that magpies, that are the main host of the great spotted cuckoo in Europe, have alleles of one microsatellite locus (Ase64) that segregate between accepters and rejecters of experimental parasitic eggs. Furthermore, differences in ejection rate among host populations exploited by the brood parasite covaried significantly with the genetic distance for this locus.

Animals↗
PubMed2001

Tissue factor/tissue factor pathway inhibitor system and long-term prognosis after acute myocardial infarction.

UNLABELLED: The tissue factor and tissue factor pathway inhibitor (TFPI) system has been studied in the acute phase of coronary disease but its prognostic importance has been less well assessed. We evaluated its association with recurrent coronary events during long-term follow-up after a myocardial infarction. METHODS: We studied 55 consecutive patients with the following criteria for inclusion: (1) first myocardial infarct; (2) aged < 70 years; (3) non-complicated infarct; (4) low risk effort-test. Blood samples were taken 60-80 days after infarction. Tissue factor, total and free-TFPI were measured. A 4-year follow-up was carried out. Death, unstable angina and new myocardial infarction were considered as poor prognosis. RESULTS: There were no statistical differences in tissue factor/TFPI levels between patients and controls. Total-TFPI showed statistical correlation with total cholesterol (r = 0.59), triglycerides (r = 0.34), LDL-cholesterol (r = 40) and Lipoprotein(a) (r = 0.48). Patients with high levels of cholesterol, LDL-cholesterol and triglycerides showed elevated levels of total-TFPI with no differences in free-TFPI. During follow-up, 8 patients showed poor prognosis. There were no statistical associations between tissue factor/TFPI levels and prognosis. CONCLUSIONS: After acute myocardial infarction, we did not find any differences in the tissue factor/TFPI system between controls and patients. The tissue factor/TFPI system showed little value as a prognostic factor.

Aged↗
PubMed1999

Sperm mobility determines the outcome of sperm competition in the domestic fowl.

The aim of this study was to establish whether the mobility of sperm of the domestic fowl, as measured by an in vitro assay, predicted the outcome of sperm competition. Thirteen pairs of New Hampshire roosters, comprising one male categorized as having high-mobility sperm and the other as having average-mobility sperm, were used. Each male provided 25 x 10(6) sperm, which were mixed and artificially inseminated into between four and seven New Hampshire hens, each of which produced 2-11 offspring. The experiment was conducted twice, such that the same pair of males inseminated the same females. Paternity was assigned by using microsatellite markers. There was a clear effect of sperm-mobility phenotype on the outcome of sperm competition: in all 13 pairs the high-mobility male fathered the majority of offspring (75.3% overall; p < 0.0001). The proportion of offspring fathered by the high-mobility male within pairs varied significantly between male pairs (p < 0.0005). This effect was associated with the difference in sperm-mobility scores between males within pairs; there was a significant positive relationship between the proportion of offspring fathered by the high-mobility male and the ratio of mobility scores between males (p < 0.05). In addition, compared with their success predicted from the non-competitive situation, in the competitive situation high-mobility males were disproportionately successful in fertilizing eggs compared with average-mobility males. This may occur because female sperm storage is limited in some way and a greater proportion of high-mobility sperm gain access to the female's sperm storage tubules. There was no evidence that female effects accounted for any of the variation in paternity.

Animals↗
PubMed1998

Hypofibrinolysis in atrial fibrillation.

BACKGROUND: There is a high incidence of systemic embolism in patients with chronic atrial fibrillation. A hypercoagulable state has been demonstrated, but the fibrinolytic system is rarely studied. METHODS: Plasma levels of modified antithrombin III (ATM), tissue plasminogen activator (TPA), its inhibitor (PAI-1), TPA-PAI-1 complexes and plasmin-antiplasmin complexes (PAP), d -dimer, and fibrinogen were measured in plasma from 36 patients with chronic atrial fibrillation. Fifteen patients had rheumatic mitral stenosis and 21 had nonrheumatic atrial fibrillation. Levels were compared with those found in the plasma of 20 healthy subjects. Transthoracic echocardiographic studies were done. RESULTS: Patients with atrial fibrillation had higher plasma levels of ATM, d -dimer, PAI-1, and TPA-PAI-1 complexes than controls (P <.001). The rheumatic atrial fibrillation group also showed elevated levels of fibrinogen (P <. 05). No significant differences were found in TPA and PAP. There were no differences between rheumatic and nonrheumatic atrial fibrillation. CONCLUSIONS: Atrial fibrillation shows a hypofibrinolytic state caused by elevated PAI-1 levels with no increase in PAP complex concentration. Elevated plasma d -dimer levels suggest increased intravascular thrombogenesis. This may contribute to increased risk of thrombosis.

Aged↗
PubMed1998

Efficacy and safety of losartan in the treatment of hypertension in renal transplant recipients.

Arterial hypertension, which represents a common problem in patients with renal transplant, contributes to the cardiovascular morbidity and mortality of these patients. The most usual immunosuppressive drugs (cyclosporine and FK-506) collaborate on the development of hypertension. Calcium channel blockers are the most habitually used antihypertensive drugs in this population, although its long-term hemodimamycs effects could be deleterious especially in transplanted patients with chronic graft nephropathy. Losartan, a specific blocker of angiotensin II (AT1) receptors, has demonstrated a potent antihypertensive effect with a good safety and tolerance profile. The glomerular effects of losartan could be useful in transplanted patients. The present open, prospective and multicenter study evaluated the efficacy and safety of losartan in the treatment of hypertension in a group of patients with a renal transplant. Seventy-six patients with systolic blood pressure > or = 140 and/or diastolic blood pressure > or = 90 mm Hg, and/or patients on therapy with one antihypertensive drug and related side effects were included. After inclusion, therapy with losartan 50 mg/24 hr was started, discontinuing the previous antihypertensive therapy and/or therapy which caused the side effects. At four weeks, if blood pressure (BP) was not controlled, hydrochlorothiazide 25 mg or furosemide 40 mg/24 hr was added. At baseline and at weeks 2, 4, 8 and 12, the following parameters were monitored: BP, creatinine, hematocrit, hemoglobin, glucose, ions, uric acid, cholesterol, triglycerides, bilirubin, SGOT, SGPT, GGT, LDH, calcium, phosphate, alkaline phosphatase, proteinuria, and both cyclosporine and FK-506 levels in whole blood. Sixty-seven patients completed the 12-week study period. Mean blood pressure decreased from 113 +/- 10 to 102 +/- 9 mm Hg at the end of the study (P < 0.0001); 38 of the 67 patients (56.7%) who completed the study had a SBP lower than 140 mm Hg and a DBP lower than 90. These blood pressures were obtained in 30 patients on monotherapy with losartan (78.9%). Proteinuria decreased significantly at week 4 and was confirmed at week 12, especially in patients with proteinuria > or = 300 mg/24 hr. Nine patients were withdrawn during the study period for different reasons. Serum creatinine showed a slight, non-clinically significant increase at week 4, remaining stable until the end of the study. Two patients developed a mild normocytic anemia, and three others presented a mild impairment of pre-existent anemia. No interactions with cyclosporine or FK-506 were described. These results indicate that losartan is effective in reducing BP in hypertensive patients with a renal transplant. It has a good tolerance profile and does not interfere with immunosuppressive therapy.

Adult↗
PubMed1996

[Heart disease in acromegaly. Study of 27 patients].

BACKGROUND: The patients with acromegaly have an increased propensity to develop cardiovascular complications. The aim of this study was to evaluate the most relevant clinic, echocardiographic and Holter recording findings in acromegaly and its correlation with the growth hormone (GH) levels and duration of the disease. PATIENTS AND METHODS: 27 patients with acromegaly were evaluated. The basal levels of GH and insulin-like growth factor 1 (IGF-1) were measured at the time of cardiological study and compared with the spontaneous GH secretion during 12-24 hours previously studied. Echocardiogram was made using complete M-mode, two dimensional and spectral Doppler ultrasound mechanical system. Additionally an standard EKG and a Holter recording were performed during 24 hours. RESULTS: There was a strong correlation between basal levels of GH and integrated concentration of GH during the study of spontaneous secretion (r = 0.92; p < 0.01). The prevalence of symptomatic cardiovascular complications in this study was 49%, including 3 patients who died for cardiovascular events. The echocardiographic study showed a high prevalence of left ventricular hypertrophy (66.7%), diastolic dysfunction (63%) and impaired systolic function (18.5%). There was no correlation between GH and IGF-1 levels and echocardiographic findings. Conversely the degree of hypertrophy was related to the duration of the disease and the presence of arterial hypertension. The diastolic function only was related with the presence of hypertension. We found supraventricular arrhythmic events and malignant premature ventricular complexes in 6 and 6 patients, respectively. The EKG showed a high fiability to detect ventricular hypertrophy but no rhythm events. CONCLUSIONS: The high prevalence of cardiovascular complications in acromegaly, most of them asymptomatic, and its clinical relevance, advise the necessity to perform systematic cardiovascular evaluation in these patients.

Acromegaly↗
PubMed1996

[The fibrinolytic system in patients with dilated myocardiopathy].

OBJECTIVES: To study the fibrinolytic system in dilated cardiomyopathy (DCM) patients, and the relationship between the degree of severity (NYHA degree), and the presence of complications (atrial fibrillation, intracavity thrombus, and peripheral embolism). We also analyzed the influence of the antithrombotic therapy on the fibrinolysis's proteins. PATIENTS AND METHODS: We included 18 patients, stratified in two etiologic groups: 9 with idiopathic and 9 with ethyl DCM. The fibrinolytic system was investigated through the plasma levels of antigenic and functional t-PA and PAI-1. We also carried out a venous occlusion test to investigate the fibrinolytic the fibrinolytic activity in t-PA secretion. The clinical aspects were recorded. We included 30 healthy individuals matched for age and sex, as controls. RESULTS: The antigenic levels of t-PA and PAI-1, were significantly higher in the DCM group than in the control group (p < 0.01). The venous occlusion test responses were normal. No relationship between the fibrinolytic parameters and clinical data were observed. DISCUSSION: The high levels of antigenic t-PA found in DCM patients were considered as a vascular injury marker, and a atherothrombotic risk factor. Furthermore, there is a hypofibrinolytic condition shown by a PAI-1 augmentation. In conclusion, we are prone to consider long term oral anticoagulation in the management of DCM patients.

Adult↗
PubMedDate not supplied

Anticoagulant therapy modifies fibrinolytic dysfunction in chronic atrial fibrillation.

OBJECTIVE: We evaluated the changes in fibrinolytic activation markers before starting anticoagulation, at 1 and 6 months following the introduction of anticoagulant therapy. DESIGN AND METHODS: Tissue plasminogen activator (t-PA), its endothelial inhibitor (PAI-1), plasmin:antiplasmin complexes (PAPc), modified antithrombin III (ATM), D dimer (D-D) and fibrinogen (FIB) were measured in 36 patients with chronic atrial fibrillation. Fifteen of them had rheumatic mitral stenosis and 21 had nonrheumatic atrial fibrillation. Basal levels were compared with a sex- and age-matched healthy control group. RESULTS: At baseline, patients with atrial fibrillation showed significantly higher plasma levels of PAI-1, ATM, D-D and FIB levels (p < 0.05) than controls, and no differences in t-PA and PAPc concentrations. Levels of t-PA, PAI-1, ATM and D-D decreased significantly under anticoagulant therapy, whereas FIB levels were not significantly modified. PAPc levels were significantly increased at 6 months in the rheumatic group but did not differ significantly in the nonrheumatic group. CONCLUSIONS: Patients with chronic atrial fibrillation show a hypercoagulant state and a relatively low fibrinolytic function. After 6 months of anticoagulant therapy, an improvement in fibrinolytic function markers was detected.

Aged↗