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Biomedical subjects

A Miralles

Publications and source records attributed to A Miralles.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Urinary albumin excretion during the night in essential arterial hypertension].

BACKGROUND: The value of nocturnal minute-by-minute urine was analyzed for the detection of microalbuminuria in high blood pressure. METHODS: Urinary albumin excretion (UAE) was measured by immunonephelometry in 70 patients with essential arterial hypertension (34 males, mean age 44 +/- 5 years, body mass index [BMI] 28 +/- 4, clinical blood pressure [BP] 157 +/- 12/97 +/- 7 mmHg) and 12 healthy normotensive controls (5 males, mean age 38 +/- 4 years, BMI 27 +/- 3; clinical BP 126 +/- 12/79 +/- 5 mmHg). Both 24 hours urine as well as nocturnal urine were collected over 2 days. The intraindividual variability was evaluated by calculation of the intraclass correlation coefficient and by the Bland and Altman method. RESULTS: Mean 24-hour UAE was 24.7 +/- 41.9 micrograms/min, greater than nocturnal urine (17.7 +/- 32.8 micrograms/min) (p < 0.05). The UAE rate was significantly greater in the hypertensive patients than in the controls (p < 0.01) for both the 24-hour and nocturnal urine. The intraindividual variability estimated as the percentage of repeatability was 35% for 24-hour UAE and 43% for nocturnal UAE, being slightly higher values than those observed in the controls. Microalbuminuria was detected in 17 (24%) of the patients in 24-hour samples while in the nocturnal urine 12.12 or 10 patients were found according to whether the threshold considered was 14 micrograms/min, 14.9 micrograms/min or 20 micrograms/min, respectively. While the specificity in nocturnal minute-by-minute urine was 98% and the positive predictive value was 0.91 for any of the thresholds considered, sensitivity ranged from 59% for the higher threshold (20 micrograms/min) to 70% for the lower threshold (14 micrograms/min). CONCLUSIONS: The determination of microalbuminuria in minuted nocturnal urine in patients with essential arterial hypertension is less sensitive than that determined in 24-hour urine.

Adult↗
PubMed1995

Valvuloplasty in traumatic aortic insufficiency due to subtotal tear of the intima.

Aortic regurgitation is one of the usual pathologic findings necessitating valve replacement in cardiac surgery. Several diseases may result in leaflet incompetence. Circumferential intimal tear of the aortic root with prolapse of the aortic valve commissures is a rare cause of aortic incompetence. We report the repair of the aortic wall and valve in 1 patient with such a tear 6 months after an important thoracic trauma. Three months after the aortic valve reconstruction the patient is in good condition and fully asymptomatic.

Aged↗
PubMed1995

Molecular characterization and isolation of a 45-kilodalton imidazoline receptor protein from the rat brain.

Imidazoli(di)nes bind to molecular entities different from alpha 2-adrenoceptors: the so-called imidazoline receptors (IRs). Two main types of IRs have been described, the clonidine- and the idazoxan-preferring types, as well as other IRs whose pharmacological properties do not fit either type, but little is known about the molecular features of these receptors. In this study, IR proteins have been solubilized from the rat brain, using the zwitterionic detergent CHAPS, and analyzed by pharmacological and immunological means two of the four peak discriminated by gel filtration chromatography using [3H]idazoxan binding and a specific antibody. The IR eluted in the first peak accounted for 80% of the specific binding of [3H]idazoxan to solubilized brain membranes, and its pharmacological features corresponded to the non-adrenoceptor component of [3H]idazoxan binding in rat brain native membranes. The elution volume of this peak corresponded to a 130-140-kDa protein, but immunoblot analysis with a specific anti-IR antiserum showed the presence of a approximate 45-kDa IR protein, suggesting that this receptor is either an oligomeric protein complex or that it is associated with other proteins. This result was in agreement with the isolation and immunodetection of a 45-kDa peptide by affinity chromatography, which supported the relationship between this protein and a rat brain imidazoline binding site. The second peak, accounting for 15% of the specific binding of [3H]idazoxan to solubilized membranes, had a Mr of approximately 65-70,000, as determined by gel filtration chromatography and immunoblotting.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1995

CD50 (intercellular adhesion molecule-3) is expressed at higher levels on memory than on naive human T cells but induces a similar calcium mobilization on both subsets.

CD50, the intercellular adhesion molecule-3 (ICAM-3), is expressed almost exclusively on hematopoietic cells. T lymphocytes display a bimodal distribution on CD50 expression levels. It was observed that CD45RO+ cells expressed higher levels of CD50 than CD45RA+ T lymphocytes. A similar situation was observed when CD4 and CD8 subpopulations were analyzed, with CD8+ cells expressing higher levels of CD50 than CD4+ cells. When adult T lymphocytes were analyzed by three-color flow cytometry in CD8+CD45RA+ cells both CD50low and CD50high expressing cells were detected, in accordance with several memory markers on T lymphocytes, whereas only cells with a low level of CD50 were observed in CD4+CD45RA+. The different level of CD50 expression was confirmed by analyzing purified CD45RA+ and CD45RO+ T cells. Moreover, after the comparison of CD50 expression level in thymocytes, cord blood and adult T lymphocytes, a progressive increase was observed. When T cells were sorted by their intensity of CD50 expression, only CD50high cells proliferated in response to tetanus toxoid. Therefore, the phenotypic and functional analysis of adult and cord blood T lymphocytes as well as thymocytes indicates that CD50 expression increases during the maturation process of T lymphocytes: from the lowest CD50 levels present on CD1+ thymocytes, to the highest levels of CD50 on human memory T cells. In addition, we have observed that after CD50 cross-linking on human T lymphocytes, a transient increase in intracellular calcium concentration ([Ca2+]i) is produced. When CD45RA+ and CD45RO+ T cells were analyzed, in spite of the level of CD50 expression, the stimulation through CD50 induced a similar level of Ca2+ mobilization in both subpopulations, contrasting with the higher rise in [Ca2+]i induced by CD3 stimulation on CD45RA+ versus CD45RO+. These data suggest that the signal transduction pathways activated after CD50 cross-linking are, at least partially, independent of those involved after CD3 stimulation.

Adult↗
PubMed1994

CD50 (intercellular adhesion molecule 3) stimulation induces calcium mobilization and tyrosine phosphorylation through p59fyn and p56lck in Jurkat T cell line.

The leukocyte differentiation antigen, CD50, has been recently identified as the intercellular adhesion molecule 3 (ICAM-3), the third counter-receptor of leukocyte function-associated antigen 1 (LFA-1). This molecule seems to be specially involved in the adhesion events of the initial phases of the immune response. To characterize the role of CD50 in leukocyte interactions, the different molecular events induced after cross-linking of CD50 on T cell-derived Jurkat cell line have been analyzed. When cells were incubated with anti-CD50 mAbs and cross-linked with polyclonal goat anti-mouse immunoglobulins, a rise in intracellular calcium concentration ([Ca2+]i) was observed. This increase in [Ca2+]i was mainly due to the uptake of extracellular Ca2+. This Ca2+ flux involved tyrosine phosphorylations and was further increased by CD3 costimulation. These data, together with those obtained by phosphotyrosine (P-Tyr) immunoprecipitation and in vitro kinase assays, suggested the involvement of protein-tyrosine kinases (PTK) in CD50 transduction pathways. By using specific antisera, the presence of p56lck and p59fyn protein tyrosine kinases (PTK) was clearly demonstrated in the CD50 immunoprecipitates. These findings suggest that the interaction of CD50 with its natural ligand (LFA-1) may result in T lymphocyte activation events, in which CD50 could play a very active role after antigen triggering.

Animals↗
PubMed1994

Signaling through CD50 (ICAM-3) stimulates T lymphocyte binding to human umbilical vein endothelial cells and extracellular matrix proteins via an increase in beta 1 and beta 2 integrin function.

Regulated adhesion of T lymphocytes to antigen-presenting cells, endothelial cells and extracellular matrix proteins is crucial in T lymphocyte activation and migration to the sites of injury. In this study, we show that three monoclonal antibodies (mAb) recognizing different epitopes on the CD50 (ICAM-3) molecule increase T lymphocyte adhesion to tumor necrosis factor (TNF)-stimulated human umbilical vein endothelial cells and extracellular matrix proteins. These phenomena are mediated by an increase in beta 1 and beta 2 integrin avidity since (a) CD50-induced adhesion to endothelial cells was abrogated by simultaneous blocking of beta 1- and beta 2-mediated adhesion pathways but not by interfering with either one individually, (b) CD50 mAb increased beta 1 integrin-mediated adhesion to extracellular matrix proteins and to fibronectin-derived synthetic peptides, (c) CD50 mAb enhanced T lymphocyte binding to ICAM-1 transfectants, and (d) CD50 mAb did not modify surface expression patterns of beta 1 or beta 2 integrins on T lymphocytes. Our data suggest that constitutively expressed CD50 (ICAM-3) can play a pivotal role in initiating a cascade of adhesion events which may be crucial in immune activation and in the development of inflammatory lesions.

Antigens, CD↗
PubMed1994

Straw thermal stabilizer for embryo cryopreservation.

Embryo cryopreservation procedures have been highly developed to support in vitro fertilization techniques, but the clinical results have not met initial expectations. Many variables influence the outcome of the embryo cryopreservation procedure. Exposure to classical freezing media does not affect further embryo development. Therefore, the first crucial step seems to be embryo thermal behavior during the freezing/thawing procedure. With the aim of avoiding thermal oscillations to the embryos due to liquid nitrogen injection into the freezing chamber, we have developed a straw thermal stabilizer (STS) cryopreservation accessory that when adapted to a programmable biological freezer offers a more exact control of the straws temperature and also a greater reproducibility of the freezing process. The STS incorporates a seeding mechanism controlled by specially designed software. For the biological assays, 2-cell mouse embryos were cooled until seeding at -7 degrees C or frozen to -120 degrees C using 1.5 M 1,2-propanediol and 0.1 M sucrose. As control groups, embryos were either untreated or were exposed to cryoprotectants, developing to blastocyst at rates of 90.8 and 88.4%, respectively. The embryos cooled until seedling or subjected to the complete freezing procedure developed into blastocysts at rates of 95.7 and 82.8%, respectively, disregarding the effect of the cryoprotectant exposure. These results show a substantial improvement in cryopreservation with no loss in embryo development due to the seeding procedure.

Animals↗
PubMed1994

Fecal excretion of alpha 1-antitrypsin in patients with Crohn's disease. A comparison of nephelometry and radial immunodiffusion.

A comparison is made of two methods for quantifying fecal alpha 1-antitrypsin (A1ATF): nephelometry (NPL) (the method habitually employed in our laboratory), and radial immunodiffusion (RID). A method is also described for extracting A1ATF from single 24-hr stool samples. The normal A1ATF values were initially established in 25 healthy controls, followed by quantification of the protein in 30 patients with Crohn's disease, with the aim of evaluating the sensitivity and specificity of the test in assaying A1ATF and alpha 1-antitrypsin fecal clearance (CLAT). The precision of the measurement method and its applicability to the A1ATF extraction process are also evaluated. The ranges of normal A1ATF and CLAT values were found to be 0-42.2 mg/24 hr and 0-12.6 ml/24 hr, respectively; sensitivity was in turn 83% and 80% for A1ATF and CLAT, respectively, with a specificity of 100% in both cases. A good correlation was observed between the A1ATF quantifications afforded by RID and NPL in both the controls and patients with Crohn's disease (r = 0.917 and 0.997, respectively). We consider that A1ATF quantification is a rapid, safe, and reproducible method that is well tolerated by the patient.

Adolescent↗
PubMed1994

Factors related to the presence of microalbuminuria in essential hypertension.

The objective of the present study was to assess factors related to the presence of microalbuminuria in essential hypertension. Ninety-five patients with essential hypertension (58 males and 37 females, mean age 38.6 +/- 6.1 years) who had never been treated previously for hypertension were included in the study. Patients with nephropathy or diabetes mellitus, hyperglycemia > 120 mg/dL, glomerular filtration rate < 80 mL/min/1.73 m2, urinary tract infection, or positive dipstick for albumin or glucose were excluded. Blood pressure, echocardiographically determined left ventricular mass, serum biochemistry, and lipid profile were obtained. Twenty-four-hour urinary albumin excretion (UAE) was measured on two separate days using an immunonephelometric assay. Microalbuminuria (UAE 30 to 300 mg/24 h) occurred in 26% of patients and was associated with higher diastolic blood pressure (DBP), left ventricular mass index (LVMI), and a higher prevalence of hypertriglyceridemia and hyperapolipoproteinemia B (apo-B). Logistic regression analysis showed that the risk of microalbuminuria was independently related to diastolic blood pressure and hypertriglyceridemia when controlling for age, sex, body mass index, LVMI, and apo-B. Multiple regression analysis likewise confirmed that both DBP and LVMI were linearly related to UAE independent of age, sex, body mass index, total cholesterol, triglycerides, and apo-B. In conclusion, our study indicates that among hypertensive patients with elevated excretion rates of urinary albumin, even at the subclinical level, an increased cardiovascular risk exists compared to normoalbuminuric patients with a similar blood pressure. Assessment of the presence of microalbuminuria may be useful in the evaluation and management of hypertension.

Adult↗
PubMed1994

Ambulatory blood pressure and microalbuminuria in essential hypertension: role of circadian variability.

OBJECTIVE: To assess the relationship of subclinical urinary albumin excretion with ambulatory and circadian variability of blood pressure. DESIGN AND METHODS: Patients with essential hypertension (82 males and 59 females, mean +/- SD age 38.9 +/- 7.3 years) who had never been previously treated for hypertension were included in the study. Patients with nephropathy or diabetes mellitus, hyperglycemia > 120 mg/dl, glomerular filtration rate < 80 ml/min per 1.73 m2, urinary tract infection and positive dipstick for albumin or glucose were excluded. Twenty-four-hour ambulatory blood pressure monitoring on a regular working day using an oscillometric device was performed. Twenty-four-hour urinary albumin excretion was measured on two separate days using an immunonephelometric assay. RESULTS: Microalbuminuric patients (urinary albumin excretion 30-300 mg/24 h, n = 31) had significantly higher mean ambulatory systolic blood pressure (SBP) and diastolic blood pressure (DBP) than those with normoalbuminuria (urinary albumin excretion < 30 mg/24 h, n = 96) during the 24-h, daytime (0800-2200 h) and night (2400-0600 h) periods, whereas for office blood pressure only DBP was significantly higher. Urinary albumin excretion was positively correlated with the means of SBP and DBP. Multiple regression analysis similarly confirmed that DBP during daytime was positively and day:night ratio of DBP inversely associated with urinary albumin excretion independent of age, sex and other parameters of ambulatory blood pressure. CONCLUSIONS: In conclusion, the present study indicates that, in middle-aged essential hypertensive patients, the presence of microalbuminuria is a marker for the presence of higher values of blood pressure throughout a 24-h period.

Adult↗
PubMed1994

Recurrent Trichosporon beigelii endocarditis after aortic valve replacement.

Fungal endocarditis of the bioprosthetic heart valve, implanted in a patient without evidence of impaired immunity, is reported. Clinical manifestations of endocarditis appeared 7 years after aortic valve replacement for rheumatic disease and included embolization into the popliteal artery. Trichosporon beigelii was isolated from the cultured fragments of the embolus. Two valve replacements were performed because of recurrent infection during the following 4 years. In spite of prolonged antifungal therapy, the patient died from multiorgan septic involvement.

Adult↗
PubMed1994

Cardiac echinococcosis. Surgical treatment and results.

During the last 15 years, eight patients with a diagnosis of hydatid cysts of the heart and one patient with a diagnosis of alveolar hydatid disease with intracardiac parasitic thrombus underwent successful operation at La Pitié Hospital. Only five cases had symptoms, and the remaining four cases were diagnosed incidentally. Serologic tests achieved a variety of results and were not determinant. All patients were examined with echocardiography and angiography, and almost all patients underwent magnetic resonance scanning. Sternotomy was the approach used, and all patients underwent operation with cardiopulmonary bypass. Surgical treatment included puncture and aspiration of the cyst content, previous sterilization with hypertonic saline solution, and excision of the cyst with closure of the cavity in seven patients with different concomitant procedures. No case of intraoperative rupture was reported, and the only complication was an atrioventricular block in a patient with a cyst of the left ventricular wall invading the intraventricular septum. There was no operative mortality, and only one late death was observed. No recurrences or associated complications were reported in the late follow-up.

Adolescent↗
PubMed1993

No effect of genetic obesity and mazindol on imidazoline I2 binding sites in the brain of Zucker rats.

The density and affinity states of imidazoline I2 binding sites as well as the density of alpha 2-adrenoceptors were quantitated in the brain of lean and obese Zucker rats. No significant differences were obtained between Zucker phenotypes for these receptors in the cerebral cortex and hypothalamus. Moreover, chronic treatment with the anorexic imidazoline derivative, mazindol, did not alter the density of brain imidazoline I2 binding sites. It is concluded that this genetic model of obesity is not associated with abnormal imidazoline I2 binding sites.

Animals↗
PubMed1993

Acute and chronic effects of reserpine on biochemical and functional parameters of central and peripheral alpha 2-adrenoceptors.

The specific binding of the agonist, [3H]UK 14304, and of the antagonist, [3H]RX 821002, to rat brain membranes, as well as clonidine-induced mydriasis, clonidine-induced inhibition and idazoxan-induced stimulation of brain 3,4-dihydroxyphenylalanine (DOPA) synthesis, and clonidine and UK 14304-induced inhibition of twitch responses in the vas deferens were used to evaluate the affinity and sensitivity of central and peripheral alpha 2-adrenoceptors after various treatments with reserpine. Treatment with reserpine (0.25 mg/kg s.c., every 48 h) for 4, 11 and 18 days induced consistent and significant increases in the affinity (KD values) of [3H]UK 14304 for the cortical alpha 2-adrenoceptor with no change in receptor density. Chronic treatment with reserpine also resulted in a greater affinity of (-)-adrenaline for the high-affinity state of the alpha 2-adrenoceptor when the catecholamine competed with the binding of [3H]RX 821002 to cortical membranes. In line with these radioligand binding data, various functional responses mediated by central and peripheral alpha 2-adrenoceptors were found to be potentiated after repeated treatment with reserpine. Thus, the inhibitory alpha 2-autoreceptor that modulates the synthesis of brain noradrenaline and the central postsynaptic inhibitory alpha 2-adrenoceptor that induces mydriasis displayed greater responses in vivo after chronic treatment with reserpine. Short-term and chronic treatments with reserpine also increased the sensitivity of peripheral presynaptic alpha 2-adrenoceptors in the vas deferens.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Agonists↗
PubMed1993

Acute and chronic effects of cholinesterase inhibitors and pilocarpine on the density and sensitivity of central and peripheral alpha 2-adrenoceptors.

The specific binding of the agonists [3H]clonidine and [3H]UK 14304 (bromoxidine) and of the antagonist [3H]RX 821002 (2-metoxy idazoxan) to rat brain membranes, as well as clonidine-induced mydriasis, clonidine-induced inhibition of brain (3,4-dihydroxyphenylalaninme) DOPA synthesis and clonidine-induced inhibition of twitch responses in the vas deferens, was used to evaluate the density and sensitivity of central and peripheral alpha 2-adrenoceptors after prolonged activation of the cholinergic system. Acute (12 h), short-term (4 days) or chronic (7-18 days) treatment with the cholinesterase inhibitors neostigmine (0.1 mg/kg), physostigmine (0.1 mg/kg) and diisopropylfluorophosphate (2 mg/kg) and with the muscarinic receptor agonist pilocarpine (10 mg/kg) did not alter the density of brain alpha 2-adrenoceptors. In contrast, various functional responses mediated by central and peripheral alpha 2-adrenoceptors were potentiated after the repeated treatments. Thus, the inhibitory alpha 2-autoreceptor that modulates the synthesis of brain noradrenaline and the central postsynaptic inhibitory alpha 2-adrenoceptor that induces mydriasis displayed greater responses in vivo after chronic treatment with neostigmine or pilocarpine. These treatments also increased the sensitivity of peripheral presynaptic alpha 2-adrenoceptors in the vas deferens. The results indicate that prolonged activation of central and peripheral cholinergic pathways results in up-regulation of alpha 2-adrenoceptor function without apparent increases in receptor density.

Adrenergic alpha-Agonists↗
PubMed1993

CDw50 and ICAM-3: two names for the same molecule.

CDw50 differentiation antigen is a molecule broadly expressed on hematopoetic cells but not on other cells. Previous experiments showed that CDw50 monoclonal antibodies (mAb) inhibited primary mixed lymphocyte culture (MLC). To understand the function of CDw50 better, we purified it and obtained peptide sequence. At the same time, intercellular adhesion molecule (ICAM)-3, the third ligand of lymphocyte function-associated molecule 1, was described by mAb and subsequent cDNA cloning. Immunochemical, functional, and protein sequencing studies show that ICAM-3 and CDw50 are the same glycoprotein, a 120-kDa surface molecule with presumably an important role in the immune responses.

Amino Acid Sequence↗