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Biomedical subjects

F Rivera

Publications and source records attributed to F Rivera.

At least 37 records · Page 2Linked to original sources
PubMed2000

G-Protein beta(3) subunit gene variant and left ventricular hypertrophy in essential hypertension.

A functional genetic variant consisting of a C825T substitution in the GNB3 gene, encoding for the G-protein beta(3) subunit, has been associated with enhanced G-protein activation and cell growth. The aim of the study was to investigate the association of this polymorphism with left ventricular hypertrophy (LVH) in a sample of patients with essential hypertension. Left ventricular mass was assessed by 2-mode echocardiography in 86 patients with essential hypertension, and GNB3 C825T genotype was determined by polymerase chain reaction and restriction digestion. Thirty-seven (0.43) patients were homozygous for the C allele (CC), 40 (0.47) were heterozygous (CT), and 9 (0.10) were homozygous for the T allele (TT). The genotype distribution among the patients was in Hardy-Weinberg equilibrium. Values of left ventricular end-diastolic diameter (52.0+/-0.7 versus 48.9+/-0.9 mm, P=0.007), posterior wall thickness (11.3+/-0.2 versus 10.6+/-0.2 mm, P=0.042), and left ventricular mass index (152.7+/-4.4 versus 135.2+/-6.4 g/m(2), P=0. 023) were significantly higher in patients with CT and TT genotypes considered together (CT+TT) than in CC patients. The distribution of the genotypes was significantly different when comparing patients with LVH: 20 (0.33) CC and 40 (0.67) CT+TT patients had this complication, and 17 (0.65) CC and 9 (0.35) CT+TT patients did not (P<0.01). The frequency of the T allele was significantly different among patients with (0.40) and without (0.20) LVH (P<0.01). A logistic regression analysis showed that the association between the T allele and LVH was independent of age, mean blood pressure, body mass index, and alcohol consumption. The relative risk of LVH in patients bearing the T allele (CT+TT group) compared with CC hypertensive patients was 3.03 (95% CI 1.14 to 8.05). The findings suggest an association between LVH and the 825T allele in hypertensive patients.

Adult↗
PubMed2000

Long-term aquaretic efficacy of a selective nonpeptide V(2)-vasopressin receptor antagonist, SR121463, in cirrhotic rats.

Water retention in experimental cirrhosis can be reversed by blocking V(2)-vasopressin (AVP) receptors with the nonpeptide antagonist OPC-31260 or by using the kappa-opioid receptor agonist niravoline, a compound inhibiting central AVP release. However, reluctance to use these drugs in human beings has emerged because the former loses aquaretic efficacy in rats after 2 days of treatment and the latter may have adverse effects in humans. Recently, a new potent and selective nonpeptide V(2)-AVP receptor antagonist, SR121463, has been developed that could be useful for the treatment of dilutional hyponatremia in human cirrhosis. The current study assessed the aquaretic efficacy of 10-day chronic oral administration of SR121463 (0.5 mg/kg/day) in cirrhotic rats with ascites and impaired water excretion after a water load (minimum urinary osmolality >160 mOsm/kg and percentage of water load excreted <60%). Urine volume (UV), osmolality (U(Osm)V), and sodium excretion (U(Na)V) were measured daily. At the end of the 10-day treatment, mean arterial pressure also was measured. In basal conditions cirrhotic rats showed ascites, sodium retention, and impaired water excretion. UV, U(Osm)V, and U(Na)V did not change throughout the study in cirrhotic rats receiving the vehicle. In contrast, SR121463 increased UV and reduced U(Osm)V during the 10-day treatment. This resulted in a greater renal ability to excrete a water load and normalization in serum sodium and osmolality. During the first 6 days of treatment, SR121463 also increased U(Na)V without affecting mean arterial pressure. These data suggest that SR121463 could be of therapeutical value for chronic management of human cirrhosis.

Animals↗
PubMed2000

A prospective multicenter comparison of peritonitis in peritoneal dialysis patients aged above and below 65 years. Levante PD Multicenter Group.

Various authors have found peritonitis rates in older peritoneal dialysis (PD) patients to be higher, similar, or even lower when compared to rates in younger populations. We prospectively analyzed all episodes of peritonitis registered in the 381 patients (219 males, 162 females; mean age, 55.5 +/- 17.0 years) who were treated with PD during four years (1993-1996) in our multicenter group. Patients were distributed into two groups. Group A included 138 patients aged 65 years or over (mean age: 72.3 +/- 5.1 years); group B included 243 patients aged below 65 years (mean age: 46.0 +/- 13.6 years). No differences were seen in general PD characteristics. Normalized protein catabolic rate (nPCR) was higher in younger patients (p = 0.001). Patients in group A experienced more peritonitis (135 episodes; 1 episode per 16.7 patient-months) than patients in group B (198 episodes; 1 episode per 21.7 patient-months; p = 0.01). Although no differences were seen in the general characteristics of the peritonitis episodes, gram-negative peritonitis and peritonitis not achieving a cure were more commonly secondary to enteric bacteria in group A (p = 0.03). We conclude that PD patients aged 65 years or over are at higher risk of peritonitis. Also, in this age group, gram-negative peritonitis and peritonitis with any evolution except cure are more likely to be due to enteric bacteria.

Age Factors↗
PubMed2000

A new method of repair for quadriceps tendon ruptures. A case report.

Rupture of the quadriceps tendon is an uncommon injury observed predominantly in subjects over 40 years old. Multiple surgical techniques have been employed to repair fresh and neglected ruptures; methods that make use of allograft and augmentation with tissues harvested from around the knee have been reported. We describe a case of surgical repair of a tendon-bone junction rupture in a 64-year-old patient by use of suture anchors to attach the tendon to bone and improve fixation of the soft tissue elements. Clinical diagnosis of rupture was confirmed radiographically and echographically. Surgical repair was performed within 24 hours of injury. Active movement of the knee started after 3 weeks and the patient was permitted to walk without weight-bearing with a knee cage. Three weeks later, he was permitted to walk with full weight-bearing unassisted by crutches; the knee cage was removed 6 weeks after surgery. At his most recent follow-up 24 months postoperative, quadriceps strength was equal to that of the controlateral knee and the patient has returned to sports and daily activities. The surgical method presented here provides a suture of the tendon ends without putting excess stress on the suture line during the period of early knee mobilization. Advantages over other techniques include reduced operative time, easy access to the implantation site, and better resistance of the suture material: the patient is thus able to initiate physical therapy earlier and more aggressively.

Humans↗
PubMed1999

Intra-arterial prourokinase for acute ischemic stroke. The PROACT II study: a randomized controlled trial. Prolyse in Acute Cerebral Thromboembolism.

CONTEXT: Intravenous tissue-type plasminogen activator can be beneficial to some patients when given within 3 hours of stroke onset, but many patients present later after stroke onset and alternative treatments are needed. OBJECTIVE: To determine the clinical efficacy and safety of intra-arterial (IA) recombinant prourokinase (r-proUK) in patients with acute stroke of less than 6 hours' duration caused by middle cerebral artery (MCA) occlusion. DESIGN: PROACT II (Prolyse in Acute Cerebral Thromboembolism II), a randomized, controlled, multicenter, open-label clinical trial with blinded follow-up conducted between February 1996 and August 1998. SETTING: Fifty-four centers in the United States and Canada. PATIENTS: A total of 180 patients with acute ischemic stroke of less than 6 hours' duration caused by angiographically proven occlusion of the MCA and without hemorrhage or major early infarction signs on computed tomographic scan. INTERVENTION: Patients were randomized to receive 9 mg of IA r-proUK plus heparin (n = 121) or heparin only (n = 59). MAIN OUTCOME MEASURES: The primary outcome, analyzed by intention-to-treat, was based on the proportion of patients with slight or no neurological disability at 90 days as defined by a modified Rankin score of 2 or less. Secondary outcomes included MCA recanalization, the frequency of intracranial hemorrhage with neurological deterioration, and mortality. RESULTS: For the primary analysis, 40% of r-proUK patients and 25% of control patients had a modified Rankin score of 2 or less (P = .04). Mortality was 25% for the r-proUK group and 27% for the control group. The recanalization rate was 66% for the r-proUK group and 18% for the control group (P<.001). Intracranial hemorrhage with neurological deterioration within 24 hours occurred in 10% of r-proUK patients and 2% of control patients (P = .06). CONCLUSION: Despite an increased frequency of early symptomatic intracranial hemorrhage, treatment with IA r-proUK within 6 hours of the onset of acute ischemic stroke caused by MCA occlusion significantly improved clinical outcome at 90 days.

Aged↗
PubMed1999

[Genetic polymorphisms of the renin-angiotensin system and essential hypertension].

BACKGROUND: The renin-angiotensin system (RAS) plays an important role in blood pressure (BP) regulation. A number of RAS polymorphisms have been linked to essential hypertension (EH), but there is uncertainty about this association in other studies. We examined whether the insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene, and the M235T and T174M polymorphisms of the angiotensinogen (AGT) gene are associated with EH in a Spanish sample of hypertensive patients. MATERIAL AND METHODS: We studied 75 patients with EH (BP > 160/100 mmHg), aged 55 (8.5) years, 30 males, systolic BP (SBP) 182 +/- (22.1) mmHg, diastolic BP (DBP) 109 +/- (9.9) mmHg (mean [SD]) and a strong family history of the disease. As a control group, 75 healthy subjects with no family history of cardiovascular disease were studied. The polymorphisms were determined by PCR amplification of genomic DNA, followed by enzyme digestion for the AGT gene polymorphisms. RESULTS: The genotype distribution and the frequencies of the alleles of the three RAS polymorphisms were similar in hypertensive and control subjects. In addition, we did not find any compound effect of the I/D ACE gene and M235T AGT gene polymorphisms on BP levels in hypertensive and control subjects. CONCLUSIONS: In this sample, the contribution of the ACE I/D polymorphism and the AGT M235T and T174M polymorphisms in the development of EH seems to be less important than previously estimated.

Adult↗
PubMed1999

Vascular endothelial growth factor production in peritoneal macrophages of cirrhotic patients: regulation by cytokines and bacterial lipopolysaccharide.

Vascular endothelial growth factor (VEGF) is an angiogenic peptide with vascular permeability and relaxing properties. This study assessed whether peritoneal macrophages of cirrhotic patients can be up-regulated to produce VEGF under proper stimulatory conditions. Macrophages were isolated from ascites. VEGF protein secretion and mRNA expression were measured in basal conditions and after stimulation with lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-alpha), and interleukin-1 (IL-1). These substances induced a time- and dose-dependent increase in both VEGF production and transcript expression. Assays with actinomycin D showed that VEGF mRNA induction is secondary to both higher VEGF gene transcription and mRNA stability. Ascites and plasma concentration of VEGF was also measured in cirrhotic patients with (n = 15) and without (n = 10) spontaneous bacterial peritonitis (SBP). Plasma values did not differ between both groups of patients. However, ascites VEGF levels were higher in SBP patients than in noninfected cirrhotic patients (710 +/- 183 vs. 94 +/- 15 pg/mL; P <.025). These results indicate that cytokines and LPS markedly increase VEGF protein secretion and mRNA expression in macrophages of cirrhotic patients, and suggest that this substance could be an important mediator of the pronounced arterial vasodilation frequently occurring in SBP patients.

Ascites↗
PubMed1999

Nitric oxide production and inducible nitric oxide synthase expression in peritoneal macrophages of cirrhotic patients.

The present study assessed whether peritoneal macrophages isolated from cirrhotic patients produce nitric oxide (NO) and express NO synthase type II (NOS II) mRNA and protein. Patients with cirrhosis and ascites without peritonitis or with unresolved or resolved spontaneous bacterial peritonitis (SBP) were studied. Following paracentesis, ascites NO(2)(-) + NO(3)(-) content (NOx) was measured. Peritoneal macrophages from ascites were seeded on well plates, and NO(2)(-) in the medium was determined. NOx was higher in patients with unresolved or resolved SBP than in cirrhotic patients without peritonitis. Macrophages of patients with SBP or resolved SBP produced NO(2)(-) after 30 hours in culture, but those obtained from patients without peritonitis did not. Reverse-transcription polymerase chain reaction (RT-PCR) and immunocytochemical analysis revealed the presence of a clear signal for NOS II mRNA and protein in macrophages of SBP patients, regardless of whether or not the infection subsided. Therefore, peritoneal macrophages isolated from cirrhotic patients with unresolved or resolved SBP produce NO and express the NOS II mRNA and protein, suggesting that NOS II may contribute to the control of SBP, or to its associated pathology, in human cirrhosis.

Adult↗
PubMed1999

Selective inhibition of cyclooxygenase 2 spares renal function and prostaglandin synthesis in cirrhotic rats with ascites.

BACKGROUND & AIMS: The critical role of cyclooxygenase (COX) products in maintenance of renal function in cirrhosis with ascites discourages the use of nonsteroidal anti-inflammatory drugs in this disease. The recent development of selective COX-2 inhibitors opens new avenues for the use of these compounds in decompensated cirrhosis. The current study evaluates the effects of a selective COX-2 inhibitor (SC-236) on renal function in cirrhotic rats with ascites. METHODS: In protocol 1, urine volume, urinary excretion of sodium and prostaglandins, glomerular filtration rate, and renal plasma flow were measured before and after administration of SC-236 (n = 12) or ketorolac (n = 10) to rats with cirrhosis. Protocol 2 was aimed at assessing the effects of COX inhibitors on renal water metabolism in 28 cirrhotic rats. RESULTS: Administration of SC-236 to cirrhotic animals did not produce significant renal effects, whereas administration of the nonselective COX-1/COX-2 inhibitor, ketorolac, resulted in a marked reduction in urine volume, urinary excretion of prostaglandins, and glomerular filtration rate and in a significant impairment in renal water metabolism. CONCLUSIONS: These findings indicate that SC-236 does not significantly impair renal function in rats with cirrhosis.

Animals↗
PubMed1999

Losartan decreases plasma levels of TGF-beta1 in transplant patients with chronic allograft nephropathy.

BACKGROUND: Chronic allograft nephropathy represents the principal cause of graft loss after the first year of transplantation. Transforming growth factor-beta1 (TGF-beta1) is a key factor in fibrogenesis and has been involved in the pathogenesis of chronic allograft nephropathy and other chronic nephropathies. Experimental studies have demonstrated that the angiotensin II receptor antagonist (losartan) could decrease the synthesis of TGF-beta1. The aim of this study was to determine the plasma levels of TGF-beta1 in transplant patients with chronic allograft nephropathy, and to evaluate the effect of losartan on TGF-beta1 plasma levels and other vasoactive peptides (angiotensin II, plasma renin activity, aldosterone, endothelin-1, and nitrites and nitrates). Angiotensin-converting enzyme genotypes were also determined in all patients. METHODS: Fourteen transplant patients with chronic allograft nephropathy were included. Treatment with losartan (50 mg) was introduced. Consecutive determinations of TGF-beta1 and other vasoactive peptides were performed during follow-up. RESULTS: Patients with chronic allograft nephropathy presented higher plasma levels of TGF-beta1 than the control groups. The treatment with losartan significantly decreased the plasma levels of TGF-beta1 (P < 0.05) and endothelin (P < 0.05) in all patients. The decrease of TGF-beta1 was statistically correlated with the blockade of the angiotensin II receptor (P < 0.05). No significant correlation could be demonstrated between angiotensin-converting enzyme genotypes and TGF-beta, endothelin-1, and nitrite-nitrate serum levels. CONCLUSIONS: This study demonstrates that losartan significantly decreases the plasma levels of TGF-beta1, the most important fibrogenetic factor. These results could play a decisive role in the treatment and prevention of chronic nephropathies, not only graft nephropathy, because the intrinsic pathogenetic mechanism is very similar in all forms, with a crucial roles for the renal renin-angiotensin system and TGF-beta1.

Adult↗
PubMed1999

Audit on the degree of application of universal precautions in a haemodialysis unit.

BACKGROUND: The purpose of the study was to investigate the degree of compliance with standard precautions (hand washing and wearing of gloves) by health workers in one haemodialysis unit. METHODS: During 4 months, two observers monitored the activities of the health care staff in the dialysis unit. Thirty five randomly distributed observation periods of 60 min duration covered one haemodialysis session. The observers evaluated (i) the total number of potential opportunities to implement standard precautions and (ii) the number of occasions when these were actually put into practice. RESULTS: A total of 364 opportunities to wear gloves and to wash hands thereafter and 273 opportunities to wash hands before a patient-oriented activity were observed. The proportion of occasions when gloves were actually used was 18.7%. Hand washing after a patient-oriented activity was performed only on 32.4% of occasions. Finally, only on 3% of such occasions was hand washing before the activity. CONCLUSIONS: The degree of compliance with standard precautions by health care personnel is unsatisfactory and this favours nosocomial transmission in haemodialysis units.

Blood-Borne Pathogens↗
PubMed1999

Comparison of two aquaretic drugs (niravoline and OPC-31260) in cirrhotic rats with ascites and water retention.

kappa-Opioid receptor agonists (niravoline) or nonpeptide antidiuretic hormone (ADH) V2 receptor antagonists (OPC-31260) possess aquaretic activity in cirrhosis; however, there is no information concerning the effects induced by the chronic administration of these drugs under this condition. To compare the renal and hormonal effects induced by the long-term oral administration of niravoline, OPC-31260, or vehicle, urine volume, urinary osmolality, sodium excretion, and urinary excretion of aldosterone (ALD) and ADH were measured in basal conditions and for 10 days after the daily oral administration of niravoline, OPC-31260, or vehicle to cirrhotic rats with ascites and water retention. Creatinine clearance, serum osmolality, ADH mRNA expression, and systemic hemodynamics were also measured at the end of the study. Niravoline increased water excretion, peripheral resistance, serum osmolality, and sodium excretion and reduced creatinine clearance, ALD and ADH excretion, and mRNA expression of ADH. OPC-31260 also increased water metabolism and sodium excretion and reduced urinary ALD, although the aquaretic effect was only evident during the first 2 days, and no effects on serum osmolality, renal filtration, and systemic hemodynamics were observed. Therefore, both agents have aquaretic efficacy, but the beneficial therapeutic effects of the long-term oral administration of niravoline are more consistent than those of OPC-31260 in cirrhotic rats with ascites and water retention.

Aldosterone↗
PubMed1998

[Evolution of the prevalence of hepatitis A antibody in Seville].

OBJECTIVE: To find the evolution of the prevalence of the Hepatitis-A antibody in Sevilla. DESIGN: Observational study of a crossover type. Comparison of results in 1995 with those from a similar study in 1981. SETTING: Health Area covered by Sevilla's University Hospital Virgen del Rocío. PATIENTS AND OTHER PARTICIPANTS: Aliquots of serum from patients without Hepatitis were obtained from the hospital's clinical analysis laboratories. MEASUREMENTS AND MAIN RESULTS: The sera were analysed in the Nuclear Medicine laboratory of the HUVR. 37.96% (62.74% in 1981) of the individuals surveyed were HA-positive. Prevalence increased with age: in the over-24s it was over 75% (90% in 1981). The differences between the two sets of results was significant (p < 0.001). CONCLUSIONS: Hepatitis-A infection is becoming less common in Andalusia, which can now be considered a low-incidence area.

Adolescent↗