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Biomedical subjects

F Rivera

Publications and source records attributed to F Rivera.

At least 73 records · Page 4Linked to original sources
PubMed1998

Angiotensin converting enzyme gene I/D polymorphism in essential hypertension and nephroangiosclerosis.

An insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene significantly influences circulating ACE levels and plays a role in the development of target organ damage, that is, left ventricular hypertrophy in essential hypertension (EH), and microalbuminuria in diabetes mellitus. We have examined the role of the I/D polymorphism in essential hypertensive patients with renal involvement. The study was divided in two independent protocols. In protocol 1, we retrospectively analyzed the ACE genotypes in 37 essential hypertensive patients with a clinical and histopathological diagnosis of nephroangiosclerosis. In protocol 2, ACE genotypes as well as microalbuminuria and renal hemodynamic parameters were investigated in 75 patients with EH with normal renal function and a strong family history of hypertension. As control group, 75 healthy subjects with BP < 130/85 mm Hg and no family history of cardiovascular diseases were studied. The ACE variants were determined by PCR and the genotypes were classified as DD, DI and II. In protocol 1, patients with nephroangiosclerosis displayed a significant difference in the genotype distribution (57% DD, 27% DI, 16% II) when compared to the control population (25% DD, 64% DI, 11% II; P < 0.001). There was no significant difference in genotype distribution between hypertensive patients with normal renal function (protocol 2; 33% DD, 59% DI, 8% II) and the control group. There were no differences in age, blood pressure, microalbuminuria and duration of the disease among the three genotypes in the EH group from protocol 2. Taken together, these findings suggest that the DD genotype of ACE is associated with histopathologic-proven kidney involvement in patients with EH and that this polymorphism could be a potential genetic marker in hypertensives at risk of renal complications.

Adult↗
PubMed1998

Haematocrit, leukocyte and platelet counts and the severity of the ovarian hyperstimulation syndrome.

Previous studies have shown that severe ovarian hyperstimulation syndrome (OHSS) is secondary to circulatory dysfunction due to the simultaneous occurrence of increased vascular permeability and marked arteriolar vasodilation which lead to an intense homeostatic stimulation of the renin-aldosterone and sympathetic nervous systems and antidiuretic hormone (ADH). In the present report, we have investigated the correlation between changes in haematocrit concentration, and white blood cell (WBC) and platelet counts and the severity of OHSS, as assessed by these markers of effective intra-arterial blood volume, in a series of 50 patients. In comparison with recovery values (4-5 weeks after hospital discharge), OHSS patients showed arterial hypotension, tachycardia, oliguria, very high plasma concentrations of renin, aldosterone, norepinephrine and ADH, and increased mean haematocrit values and WBC and platelet counts. The haematocrit concentration values were directly related to the plasma concentrations of vasoactive substances (plasma renin activity, aldosterone, norepinephrine and ADH) during OHSS (P < 0.001). In contrast, no correlation was evident between WBC or platelet counts and neurohormonal measurements during the syndrome. It is concluded that haematocrit, but not WBC or platelet counts, can act as a biological marker of the severity of OHSS as indicated by plasma measurement of volume-dependent endogenous vasoactive substances.

Adult↗
PubMed1998

An immunological strategy To monitor In situ the phosphate starvation state in thiobacillus ferrooxidans

Thiobacillus ferrooxidans is one of the chemolithoautotrophic bacteria important in industrial biomining operations. During the process of ore bioleaching, the microorganisms are subjected to several stressing conditions, including the lack of some essential nutrients, which can affect the rates and yields of bioleaching. When T. ferrooxidans is starved for phosphate, the cells respond by inducing the synthesis of several proteins, some of which are outer membrane proteins of high molecular weight (70,000 to 80,000). These proteins were considered to be potential markers of the phosphate starvation state of these microorganisms. We developed a single-cell immunofluorescence assay that allowed monitoring of the phosphate starvation condition of this biomining microorganism by measuring the increased expression of the surface proteins. In the presence of low levels of arsenate (2 mM), the growth of phosphate-starved T. ferrooxidans cells was greatly inhibited compared to that of control nonstarved cells. Therefore, the determination of the phosphorus nutritional state is particularly relevant when arsenic compounds are solubilized during the bioleaching of different ores.

Journal Article↗
PubMed1998

[Risk factors for psychomotor development among infants born under optimal biological conditions].

OBJECTIVE: The objective of this study is to evaluate the effect of risk factors on infant development, among low socioeconomic children born under optimal biological conditions, and who are exposed to adverse social circumstances. METHOD: Infants of both sexes, in the amount of 788, were studied and controlled prospectively at between 6 and 12 months. Their mental (MDI) and psychomotor (PDI) development was evaluated using the Bayley Scale of Infant Development. Eighteen risk factors were identified and dichotomized (high or low risk). RESULTS: Breast feeding, child temperament, maternal intelligence and home stimulation are consistently associated with lower MDI and PDI. After adjustment for co-variables, home stimulation persisted as a significant factor for explaining the variation of both developmental indexes and child sex also appears as a risk factor for motor skills development. The accumulated effect of 7 or more risk factors is associated with a significant decrease of development scores. The combination of risk categories of child temperament, maternal IQ, paternal role and home stimulation shows higher prediction power for infant development than other combinations analyzed in this study. CONCLUSION: The findings suggest than even for children born under optimal biological conditions their psychomotor development is negatively affected by the presence of simultaneous adverse environmental conditions.

Child Development↗
PubMed1997

Impairment of renal function during moderate physical exercise in cirrhotic patients with ascites: relationship with the activity of neurohormonal systems.

Moderate physical exercise does not affect glomerular filtration rate (GFR) and renal excretory function in normal subjects. This study is aimed at assessing the effects of moderate physical exercise on renal function in 21 nonazotemic cirrhotic patients with ascites. Arterial pressure, heart rate, and renal function were assessed in the patients after 2 hours in the supine position and during 30 minutes of moderate cycloergometric exercise in the sitting position. The activity of the renin-aldosterone and sympathetic nervous systems and the plasma levels of antidiuretic hormone (ADH) and atrial natriuretic peptide (ANP) were determined at the end of each period. Physical exercise induced a marked reduction in GFR (75 +/- 10 to 49 +/- 6 mL/min), free-water clearance (6.1 +/- 1 to 3.4 +/- 1 mL/min), and sodium excretion (7.8 +/- 2 to 4.3 +/- 1 microEq/min) in 10 patients (Group I). In the remaining 11 cases (Group II) there were no changes in these parameters. Renal perfusion significantly decreased in both groups although the reduction was greater in Group I (-34.7% +/- 4.6% vs. -7.5% +/- 3.1%, P < .001). Physical exercise was associated with a significant and comparable increase in arterial pressure, heart rate, and plasma levels of renin, aldosterone, and norepinephrine (NE) in the two groups of patients. The ANP concentration did not change. Patients from Groups I and II differed significantly (P < .05) only in plasma renin activity (PRA) and NE concentration, which were higher in Group I patients both in the supine rest (renin: 4.7 +/- 1.6 vs. 1.4 +/- 0.5 ng/mL x h; NE: 576 +/- 115 vs. 288 +/- 42 pg/ mL) and during exercise (renin: 7.1 +/- 1.8 vs. 2.6 +/- 1 ng/ mL x h; NE: 925 +/- 135 vs. 630 +/- 90 pg/mL). In conclusion, moderate physical exercise has no detrimental effects on renal function in cirrhotic patients with ascites with no or mild activation of the renin-aldosterone and sympathetic nervous systems. However, moderate physical exercise causes a marked impairment in the renal function of patients with ascites with marked stimulation of these vasoconstrictor systems.

Ascites↗
PubMed1997

Effect of bacterial lipopolysaccharide on endothelin-1 production in human vascular endothelial cells.

BACKGROUND/AIMS: The plasma levels of endothelin (ET) are 2-5 fold higher in patients with cirrhosis than in healthy subjects. It has been proposed that endotoxemia could be a mechanism responsible for this phenomenon. However, investigations in rats with cirrhosis indicate that a differential regulation for prepro ET-1 mRNA expression occurs in the liver tissue of these animals but not in the aorta or other organs. The aim of the study was to investigate the effect of bacterial lipopolysaccharide (LPS) on endothelin-1 synthesis and release in cultured human vascular endothelial cells (HUVEC). METHODS: Confluent HUVEC at passage levels 3 and 4 were exposed to increasing doses of LPS (1-1000 ng/ml) for 4 h at 37 degrees C and prepro ET-1 mRNA accumulation and big ET-1 and ET-1 concentrations in the conditioned medium were measured. RESULTS: Endotoxin had a dual effect on HUVEC. LPS at doses ranging between 250 and 1000 ng/ml induced a progressive diminution in ET-1 concentration in the culture medium. However, lower LPS concentrations dose-dependently increased big ET-1 and ET-1 release by HUVEC without altering prepro ET-1 mRNA expression. CONCLUSIONS: These results suggest that low LPS concentrations promote ET-1 release in HUVEC by a post-transcriptional mechanism located upstream of big ET-1 in the biosynthetic pathway of ET-1. These findings could explain the existence of high circulating levels of ET-1 in cirrhosis in spite of transcriptional activation of prepro ET-1 mRNA only occurring in the liver.

Cells, Cultured↗
PubMed1997

Urinary endothelin-like immunoreactivity in patients with cirrhosis.

BACKGROUND/AIMS: To investigate a possible relationship between the renal production of endothelin and the presence of renal dysfunction and activation of vasoactive systems in cirrhosis, the urinary excretion and the circulating plasma levels of immunoreactive endothelin (irET) and the plasma levels of vasoactive hormones were measured in 19 healthy subjects, 12 cirrhotic patients without ascites and 39 patients with ascites and different degrees of renal dysfunction. METHODS: The urinary excretion and the circulating levels of irET were assessed after 5 days on a 40 mEq sodium diet and off diuretics. Renal function parameters and the plasma levels of vasoactive hormones were also measured. RESULTS: Patients with and without ascites had similar values of urinary irET as compared with healthy subjects (30+/-3, 31+/-3 and 29+/-2 ng/day, respectively, p>0.10). By contrast, patients with ascites had higher circulating levels of irET (15+/-1.2 pg/ml) than patients without ascites and healthy subjects (11+/-1.6 and 5+/-0.4 pg/ml, p<0.01). In patients with cirrhosis, no correlation was found between urinary irET and circulating irET. Moreover, urinary irET did not correlate with liver tests, serum and urine sodium, glomerular filtration rate or vasoactive substances. Patients with hepatorenal syndrome had similar urinary irET to patients with ascites without hepatorenal syndrome. CONCLUSIONS: Urinary excretion of irET is not increased in cirrhotic patients with ascites and does not correlate with abnormalities in renal function.

Adult↗
PubMed1997

Mediastinal non-seminomatous germ cell tumours (MNSGCT) treated with cisplatin-based combination chemotherapy.

BACKGROUND: Primary mediastinal non-seminomatous germ cell tumours (MNSGCT) constitute a rare malignancy. This study was performed to review our experience with cisplatin-based chemotherapy in patients with MNSGCT. PATIENTS AND METHODS: Patients with MNSGCT treated with cisplatin-based combination chemotherapy between 1978-1995 in three university hospitals in Spain were retrospectively studied. RESULTS: There were 25 males and two females with a median age of 26 years (range 4-71). Fifteen patients had disease confined to the mediastinum and 12 had metastatic disease. All patients were treated with cisplatin chemotherapy regimens (PVB: 7, BEP: 6, and other regimens 12) and considered for residual mass surgery (RMS) when indicated. Eleven patients (40.7%) were rendered disease-free with initial treatment: four with chemotherapy alone, one with surgery plus adjuvant chemotherapy and six with chemotherapy plus RMS. Three of these patients relapsed at two, six and seven months. The remaining 16 had unfavourable responses (five partial response, three no change, seven progressive disease and one toxic death). Eleven patients received salvage treatment but none of them achieved a durable response. After a median follow-up of 77 months (range 1-168), 10 patients remain alive. Actuarial survival at five years is 31.7%. No patients in this series developed a haematological malignancy. Chromosomal analysis showed that 2 out of 10 patients (20%) had a 47XXY karyotype. CONCLUSIONS: Only patients who achieved disease-free status are likely to be cured. Therefore, new up-front strategies are needed for the treatment of MNSGCT.

Adolescent↗
PubMed1997

Nitric oxide production by peritoneal macrophages of cirrhotic rats: a host response against bacterial peritonitis.

BACKGROUND & AIMS: Patients and rats with cirrhosis and ascites are prone to develop peritonitis. The aim of this study was to assess whether peritoneal macrophages of cirrhotic rats without peritoneal infection produce nitric oxide and express inducible NO synthase (iNOS). METHODS: NO2- accumulation produced by macrophages from control rats and cirrhotic rats with ascites was determined. iNOS messenger RNA and protein expression were analyzed by Northern and Western blot and immunocytochemical analysis. The in vivo effects of inhibiting iNOS were investigated by giving the specific iNOS inhibitor L-N-(1-iminoethyl)-lysine (L-NIL) or sterile saline to 9 and 7 cirrhotic rats with ascites, respectively. RESULTS: Cirrhotic macrophages produced NO2- that was around fourfold greater than that of control macrophages after 30 hours in culture. Northern and Western blot and immunocytochemical analysis showed the presence of iNOS messenger RNA and protein in macrophages of cirrhotic rats. Ascites cultures were positive in all rats administered L-NIL and negative in those administered saline. CONCLUSIONS: Macrophages of cirrhotic rats produce NO and express iNOS messenger RNA and protein, and these changes are not a consequence of overt bacterial infection. Because iNOS inhibition results in peritoneal infection, these results suggest that iNOS induction in macrophages of cirrhotic rats is a host defense response to prevent bacterial peritonitis.

Animals↗
PubMed1997

Hyperplastic foveolar gastropathies and hyperplastic foveolar gastritis.

Thirteen gastrectomy specimens having diffuse (n = 5), focal (i.e., nodular, n = 6) or combined (n = 2) giant hypertrophic folds at gross examination were reviewed. Of the five specimens with grossly diffuse hypertrophic fundic mucosal folds, two had at histology tortuous foveolar hyperplasia (without intraepithelial lymphocytosis) and prominent glandular cysts; they were classified as Ménétrier's gastropathy. The other three specimens with diffuse foveolar hyperplasia had serrated foveolar infoldings with marked intraepithelial lymphocytosis; they were classified as Ménétrier-like lymphocytic gastritis. Of the six, specimens with multiple mucosal nodules at gross examination, four had focal foveolar hyperplasia with crest depression and no intraepithelial lymphocytosis; they were classified as varioliform gastropathy. The other two specimens with multiple nodules at gross examination had focal foveolar hyperplasia with marked intraepithelial lymphocytosis; they were classified as varioliform gastritis. In the remaining two cases, both diffuse and nodular hypertrophic gastric mucosa were found at gross examination; at histology, both foveolar hyperplasia and intraepithelial lymphocytosis were found. The diffuse or focal distribution of the lesions, the occurrence of intraepithelial lymphocytosis and the architecture of the upper part of the crypts (in diffuse foveolar hyperplasias) were valuable criteria in the differential diagnosis between the various types of foveolar hyperplasia of the stomach.

Aged↗
PubMed1997

Glucose regulation of islet amyloid polypeptide gene expression in rat pancreatic islets.

Intracellular pathways by which glucose regulates islet amyloid polypeptide (IAPP) gene expression in pancreatic islets were studied. IAPP mRNA levels were threefold higher in islets cultured with 16.7 mM glucose compared with control (5.5 mM glucose). Mannose and amino acids but not 2-deoxyglucose or 6-deoxyglucose mimicked the effect of glucose. Mannoheptulose (a glycolysis inhibitor) and verapamil and diazoxide (which affect calcium signaling pathway) abolished the difference in islet IAPP mRNA content between high and low glucose. At low glucose, IAPP mRNA levels were increased 1.9-fold in islets treated with forskolin or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) but not with 12-O-tetradecanoylphorbol 13-acetate. Insulin mRNA levels were 1.6-fold higher in islets cultured at high glucose than controls; glucose metabolism was required, whereas no effects of cAMP or diazoxide were observed. IAPP and insulin were cosecreted into the media. We conclude that glucose regulation of IAPP mRNA abundance requires intracellular metabolism of the hexose and that calcium may serve as a mediator of this effect; cAMP but not protein kinase C possibly participates in this regulation.

Amyloid↗
PubMed1996

Acute phase is the only significantly reduced component of the injury response after laparoscopic cholecystectomy.

The objective demonstration of improved postoperative recovery suggests that the surgical injury response induced by the laparoscopic approach is less intensive than that after open surgery. Twenty-five patients diagnosed as having noncomplicated gallstones were studied prospectively. They were operated by laparoscopy (group I, n = 12) or open surgery (group II, n = 13). Analgesia requirements (p < 0.026) and postoperative stay (p < 0.001) were significantly less in group 1. Cholecystectomy performed by either technical options induced a significant increase over basal values of glucose, lactate, white blood cell count, prolactin, ACTH, cortisol, interleukin 6, C-reactive protein, and PCO2. Both surgical procedures induced a significant reduction of total proteins, albumin, prealbumin, free fatty acids hemoglobin, hematocrit, and pH. There were no differences between the levels of growth hormone, insulin, glucagon, or PO2 during any of the periods studied. Comparison of the results of the two cholecystectomy techniques showed that laparoscopic cholecystectomy induced a significantly less intensive acute-phase response (area under the curve) of interleukin 6 (17 +/- 17 versus 47 +/- 26 pg/ml x hr x 10(2); p < 0.003), C-reactive protein (16 +/- 12 versus 35 +/-16 mg/dl x hr x 10; p < 0.004), and prealbumin (16 +/- 2.7 versus 13.8 +/- 2.3 mg/dl x hr x 10(2); p < 0.05). The surgical injury response after laparoscopic cholecystectomy is similar to that after open cholecystectomy, but the aeute-phase response component is less intense. This finding may be a consequence of the reduced size of the operative wound with laparoscopic cholecystectomy.

Adrenocorticotropic Hormone↗
PubMed1996

Intermediate filament aggregates in mitoses of primary cutaneous neuroendocrine (Merkel cell) carcinoma.

Primary cutaneous neuroendocrine carcinomas express different kinds of intermediate filaments and frequently in a 'paranuclear globular' pattern. We have observed the same pattern not only in interphase but also in mitotic cells, which are very frequent in these tumours. We report a quantitative and morphological study of eight primary cutaneous neuroendocrine carcinomas stained with different antibodies against cytokeratins (CAM 5.2 and anticytokeratin 20), neurofilaments (70 kDa and 200 kDa) and peripherin. We have found a predominance of CAM 5.2 expression in interphase cells and of neurofilament proteins in mitotic cells; 87.02% of the interphase cells were positive with CAM 5.2 whereas only 6.08% were positive for neurofilaments (P < 0.01); 35.41% of the mitotic cells were positive with CAM 5.2, whereas 50% were positive for neurofilaments (P < 0.01). A correlation between a globular pattern of intermediate filament proteins and prognosis has not been found. We describe for the first time the division of neoplastic cells with a globular pattern; the presence of intermediate filament proteins with a globular pattern in all mitotic stages; and the uneven distribution of this formation between the two daughter cells.

Aged↗
PubMed1996

Increased nitric oxide synthase expression in arterial vessels of cirrhotic rats with ascites.

Arterial vasodilatation is thought to play a major role in the pathogenesis of systemic hemodynamics and renal disturbances occurring in cirrhotic patients. Recent investigations suggest that an increased vascular nitric oxide (NO) production could be implicated in this abnormality. The current study assessed whether increased expression of inducible and/or endothelial nitric oxide synthase (iNOS and eNOS, respectively) occurs in arterial vessels of cirrhotic rats. The investigation was performed in thoracic and abdominal aortas and mesenteric arteries of 10 control rats and 16 cirrhotic rats with ascites. iNOS and eNOS messenger RNA (mRNA) expression were evaluated by polymerase chain reaction and ribonuclease protection assay, respectively. Endothelial NOS protein expression was assessed by Western blot. No iNOS mRNA was detected in arterial vessels of control rats. In contrast iNOS mRNA was consistently detected in all arteries of cirrhotic rats with ascites, the weakest signal being observed in the thoracic aorta and the strongest in the mesenteric artery. Enhanced eNOS mRNA abundance was found in the aorta of cirrhotic animals as compared with controls. Higher eNOS protein expression was noted in the thoracic aorta of cirrhotic rats. These results indicate the existence of increased eNOS and iNOS expression in arterial vessels of cirrhotic rats, suggesting that transcriptional activation of vascular NOSs and the associated nitric oxide hyperproduction may be of major importance in the pathogenesis of arterial vasodilation in cirrhosis.

Animals↗