PubMed Health⌕ Search

Biomedical subjects

M L Miranda

Publications and source records attributed to M L Miranda.

At least 19 recordsLinked to original sources
PubMed2001

Phenotypic changes in Arabidopsis caused by expression of a yeast vacuolar Ca2+/H+ antiporter.

In plants, cytosolic Ca2+ levels are tightly regulated, and changes in cytosolic Ca2+ have been implicated in converting numerous signals into adapted responses. Vacuolar ion transporters are thought to be key mediators of cytosolic Ca2+ concentrations. In an attempt to interpret the role of vacuolar Ca2+ transport in plant processes, we have expressed the yeast vacuolar Ca2+/H+ antiporter, VCX1, in Arabidopsis and tobacco. This transporter localizes to the plant vacuolar membrane. VCX1-expressing Arabidopsis plants displayed increased sensitivity to sodium and other ions. These ion sensitivities could be suppressed by addition of calcium to the media. VCX1-expressing plants demonstrated increased tonoplast-enriched Ca2+/H+ antiport activity as well as increased Ca2+ accumulation. These results suggest that VCX1 expression in Arabidopsis could be a valuable tool with which to experimentally dissect the role of Ca2+ transport around the plant vacuole.

Antiporters↗
PubMed2001

Apolipoprotein E gene polymorphism is related to metabolic abnormalities, but does not influence erythrocyte membrane lipid composition or sodium-lithium countertransport activity in essential hypertension.

The aim of this study was to analyze the influence of the apolipoprotein E (apoE) gene polymorphism on insulin resistance and plasma lipid composition of essential hypertensive patients. A secondary objective was to analyze if differences regarding plasma lipids had an effect on the erythrocyte membrane lipid composition and the activity of the erythrocyte membrane sodium-lithium countertransport. We studied 128 untreated nondiabetic essential hypertensive patients enrolled from our outpatient clinic. We considered as hyperinsulinemic all subjects having more than 80 mU/L of plasma insulin 120 minutes after a 75-g oral glucose intake. The number of hyperinsulinemic subjects among carriers of the epsilon4 allele was higher that in epsilon4 noncarrier subjects (13 of 19 v45 of 109, P < .05; odds ratio [OR], 3.08; confidence interval [CI], 0.99-10.57). Plasma insulin at baseline and plasma insulin and glucose at 120 minutes after overload was higher in carriers of the epsilon4 allele (respectively, 17.5 +/- 6.9 v 12.4 +/- 4.9 mU/L, P < .01; 111.9 +/- 39.9 v 88.7 +/- 48.2, P < .05; and 143.8 +/- 29.3 v 121.2 +/- 30.8 mg/dL, P < .005). Subjects with the epsilon4 allele had a plasma lipid profile more atherogenic than those without this allele. This profile was mainly characterized by higher levels of low-density lipoprotein (LDL) cholesterol (150.1 +/- 31.2 v 133.0 +/- 34.3 mg/dL, P < .05) and very-low-density lipoprotein (VLDL) triglycerides (134.7 +/- 85.5 v 99.2 +/- 68.8 mg/dL, P < .05) and by lower levels of high-density lipoprotein (HDL) cholesterol (41.8 +/- 10.7 v 50.0 +/- 14.7 mg/dL, P < .05). There were no differences between groups regarding erythrocyte membrane cholesterol or phospholipids composition and sodium-lithium countertransport (SLC) activity.

Adult↗
PubMed2000

[Prevalence of dyslipidemia and its phenotypes in recently diagnosed essential arterial hypertension].

BACKGROUND: To know the prevalence of phenotypic dyslipidemias and their clinical and metabolic characteristics in recently diagnosed hypertensive patients. METHODS: Consecutive study of 158 essential hypertensive patients without previous pharmacological treatment. RESULTS: 69.6% of the patients had some kind of dyslipidemia, being the isolated increase of Lp(a) (27.3%) the most prevalent and the hyperapobetalipoproteinemia the less (10.0%). Age, sex, smoking, alcohol consumption, uric acid, systolic and pulse pressure and serum glucose were different among phenotypes. CONCLUSIONS: Essential hypertensive patients have high and heterogeneous prevalence of dyslipidemias.

Adult↗
PubMed2000

Gordon's syndrome: increased maximal rate of the Na-K-Cl cotransport and erythrocyte membrane replacement of sphingomyelin by phosphatidylethanolamine.

OBJECTIVE: Gordon's syndrome comprises hypertension, hyperchloremic acidemia, hyperkalemia and intact renal function. We hypothesize that disturbances of one or more cell membrane ion carriers, handling sodium, chloride and potassium, might be relevant in this disorder and, furthermore, that such disturbances might be related to altered.cell membrane composition. DESIGN AND METHODS: In a patient diagnosed with Gordon's syndrome, we assessed the kinetics (K(m) and maximal rate) of four membrane sodium transport systems in sodium-enriched erythrocytes, according to the technique of Garay. We also measured the lipid composition of erythrocyte membrane in this patient and 69 essential hypertensive controls, using the latroscan technique. RESULTS: Compared to reference values of patients with essential hypertension, this patient exhibited a marked increase in the maximal rate of the Na+-K+-2Cl(-)-cotransport (964.0 micromol/l per cell versus the 391.6 +/- 222 micromol/l per cell in essential hypertensives). Also, there was an increased concentration of erythrocyte membrane phosphatidylethanolamine and a reduced concentration of sphingomyelin (27.9 and 11.1% versus 17.9 +/- 3.8% and 18.2 +/- 3.4%, respectively). CONCLUSIONS: We conclude that this abnormality in membrane Na+-K+-2Cl- cotransport could be responsible for the hyperkalemia, hyperchloremic acidemia and increased reabsorption of sodium observed in this condition and, furthermore, that such disturbance in membrane cotransport might be related to altered phospholipid concentration in cell membranes.

Adolescent↗
PubMed1999

Prevalence of attention-deficit/hyperactivity disorder symptoms in 4- to 17-year-old children in the general population.

The purposes of this study were (a) to estimate the prevalence of Attention-Deficit/Hyperactivity Disorder (AD/HD) symptoms in the general preschool and school population; and (b) to analyze the influence of gender, age, and socioeconomic status (SES) variables on AD/HD symptoms. Out of the 80,000 preschool and schoolchildren living in Manizales, Colombia, a random sample of 540 children was selected. Two gender, three age (4- to 5-year olds, 6- to 11-year olds, and 12- to 17-year olds), and three SES (low, middle, and high) groups were used. The 18 DSM-IV symptoms corresponding to AD/HD Criterion A were assessed on a scale of 0 (never) to 3 (almost always). All three demographic variables established statistically significant differences: AD/HD symptoms were more frequent in 6- to 11-year-old, low-SES, male participants. DSM-IV Criterion A for AD/HD was fulfilled by 19.8% of the boys and 12.3% of the girls. However, this difference was marginally significant only in the AD/HD Subtype I: Combined. It was concluded that demographic variables are significant correlates of the AD/HD diagnosis. The prevalence found in this study was higher than usually reported, even though only the symptomatic DSM-IV AD/HD criterion was analyzed. We failed to confirm the assumed AD/HD gender ratio.

Adolescent↗
PubMed1998

[Economic impact of a health care program on antibiotics].

The increased use of more expensive broad-spectrum antibiotics has had an impact on health care costs and the potential emergence of antimicrobial resistance. Antimicrobial drug prescription programs resulted in a significant reduction in the inappropriate use of certain antibiotics and in the pharmacy budget. The authors present the economic impact of an antimicrobial drug prescription program in a small community hospital.

Anti-Bacterial Agents↗
PubMed1997

[Hypertensive subpopulations as defined by their natriuretic response to ambulation].

BACKGROUND: The heterogeneity among patients with essential hypertension is known. We observed in an earlier study a large spread in the values of fractional excretion of sodium in a group of subjects with mild essential hypertension after ambulation, suggesting possible subgroups among them. We defined as the retainer (R) group that which presented a reabsorption index (RI = fractional excretion of sodium during supine/fractional excretion of sodium after ambulation) < 2.5 and the non-retainer (NR) group as that whose RI < 2.5. We analyzed at what level the reabsorption of Na was produced and the differences between the possible groups. PATIENTS AND METHODS: We studied 51 mild essential hypertensive patients, 22 men and 29 women, in two consecutive periods -recumbent, 90 minutes; ambulation, 90 minutes-. We calculated the clearance of creatinine and lithium, fractional proximal and distal reabsorption of Na, plasma renin activity (PRA), plasma aldosterone (ALDO) and elimination of PGE2 and kallikrein in the urine; the plasma catecholamines at the end of the recumbent position and after 10 minutes in the upright position. The study was taken after at least ten days without treatment and following a diet with free Na intake. RESULTS: We did not encounter significant differences between the retainer (n = 19) and non-retainer (32) group with regard to age, sex, body mass index or elimination of Na/24 h. The lower natriuresis in ambulation in the R group compared with the NR group is due to a higher fractional reabsorption of sodium, proximal (83.7 +/- 4.9% vs 79 +/- 5.2; p < 0.01) as well as distal (96.8 +/- 2 vs 95.3 +/- 2%; p < 0.05). The increment in the PRA was greater in the R group (1.3 +/- 1.4 vs 0.8 +/- 0.8; p < 0.05) after ambulation; in the R group showed a lower index -increment in ALDO/increment in PRA- in response to postural change although without significancy. We observed a lower elimination of PGE2 and kallikrein in the R group as compared with NR group (p < 0.05). We did not find differences with regard to plasma catecholamines. CONCLUSIONS: Ambulation allows to distinguish two groups of essential hypertensive patients according to natriuresis. The lower natriuresis in ambulation on the part of the R group could be due to the increase in PRA and therefore of the angiotensin II at the level of the proximal tubule, and to a lower activity of natriuretic hormones (PGE21 kallikrein) at the distal level.

Adult↗
PubMed1996

Modifications induced by -10 degrees Trendelenburg's posture in sodium tubular handling in patients with essential hypertension.

In essential hypertensive patients "exaggerated natriuresis" is a response to acute volume expansion. However, the underlying mechanisms for this remain to be determined. We studied 19 patients with essential hypertension (HP) and 9 normotensive subjects (NS). In all examined subjects the response to acute central volume expansion, without the plasma compositional change that Trendelenburg's position involves, was evaluated during 90 min (period T) after a similar period of deambulation (period D). Mean blood pressure (MBP), tubular sodium handling by the lithium clearance technique, plasma renin activity (PRA), plasma aldosterone (PA), plasma catecholamines and urine prostaglandine E2 and kallikrein were assessed after D and T. MBP was significantly higher in HP than in NS (p = 0.00001). HP showed "exaggerated natriuresis" after T (fractional excretion of sodium increased from 0.55 +/- 0.1% after D to 1.20 +/- 0.2% after T, p < 0.01). This was because of a decrease in their proximal fractional reabsorption of sodium (from 74.96 +/- 1.8% after D to 62.50 +/- 2.8% after T, p < 0.01). Plasma epinephrine and plasma dopamine after T were significantly lower than in standing position in HP (p < 0.01) but no in NS. The decrease in plasma renin activity after T in HP was 53%, and 32% in NS. There were not any significant differences between groups in the other neurohormonal systems studied. We conclude that the major determinant of "exaggerated natriuresis" in hypertensive patients is a higher stimulation of the cardiopulmonary receptors following Trendelenburg's position and consequently stronger reflex inhibition of sympathetic system activity and renin-angiotensin II activity. The "exaggerated natriuresis" after Trendelenburg's position in HP was an expression of abnormal pressure natriuresis.

Adult↗
PubMed1995

Description of a new quotient that may differentiate blood pressure profiles in essential versus Cushing's syndrome-related hypertension.

Since the presence or absence of a nocturnal decrease in blood pressure values (BP) may suggest an increased risk of visceral complications or the existence of secondary hypertension, several methods have been described for evaluating the BP profile. Nevertheless, a universally accepted system to evaluate this item has not yet been established. Our aim in this study was to test different dispersion quotients (DQ) which estimate the differences between the mean of each hour, and the mean of all the readings in the 24 h period. These quotients may be employed regarding systolic (SBP) or diastolic (DBP) blood pressure, and may be referred to the whole period of 24 h, or to the subperiods morning (m), afternoon (a) or night (n). We have studied two non selected groups of essential (n = 20) or secondary (Cushing's syndrome, n = 17) hypertensives. We observed a marked decrease in these quotients, particularly DQ-SBP and nDQ-SBP, in secondary hypertensives (respectively 10.2 +/- 2.9 vs 15.6 +/- 4.2 and 11.8 +/- 5.0 vs 20.5 +/- 6.3, p < 0.0001), thus indicating, a blunted nocturnal fall of BP in these patients. Also the DQ and particularly DQ-SBP, nDQ-SBP and nDQ-DBP, showed a high positive and negative predictive value, sensitivity and specificity for pertaining to the Cushing's syndrome group (respectively: 0.75, 0.88, 0.88, 0.75; 0.86, 0.82, 0.77 0.90; and 0.78, 0.84, 0.82, 0.80).

Adolescent↗
PubMed1995

Two different dosages of cefotaxime in the treatment of spontaneous bacterial peritonitis in cirrhosis: results of a prospective, randomized, multicenter study.

Cefotaxime (CTX) is considered one of the first-choice antibiotics in the therapy of spontaneous bacterial peritonitis (SBP) in cirrhosis. Because CTX is largely metabolized in the liver, this drug may also be effective in SBP by administering lower doses than those habitually used. To investigate this possibility, a prospective, randomized, multicenter study was performed to compare the therapeutic efficacy of two different dosages of CTX in 143 patients with SBP: 71 (group I) were allocated to receive a high dose (2 g every 6 hours, which is one of the most frequently recommended doses in this infection), and 72 (group II) were allocated to receive a low dose (2 g every 12 hours). At inclusion, both groups were similar in relation to clinical and laboratory data, with the exception of a higher incidence of positive ascitic fluid culture in group I than in group II (59% vs. 40%; P = .029). The rate of infection resolution was similar for both groups (77% vs. 79%). Hospital survival was also similar in both groups (69% vs. 79%). No difference was observed between patients with positive or negative ascitic fluid cultures with regard to infection resolution and patient survival. The duration of antibiotic therapy was similar in both groups (9.0 +/- 3.3 days in group I vs. 8.8 +/- 3.1 days in group II). In a subset of 13 patients from group I and 11 patients from group II CTX levels were determined in serum (peak and trough) and ascitic fluid (concomitantly with trough serum). Peak serum levels were similar in patients from both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Ambulatory blood pressure monitoring in physicians working in a hospital: is there an increase in the number of subjects with high workplace blood pressures?

Sixty-two physicians from our hospital who were normotensives, as supported by casual blood pressure measurements, underwent 24-h blood pressure monitoring which included their normal work, home rest and sleep periods. During working hours, 19% of the subjects showed mean diastolic and/or diastolic plus systolic blood pressures higher than those admitted as normal by the WHO for casual measurements for out of work subjects. Both mean systolic and diastolic blood pressure measurements, during the work at the hospital, were significantly higher in males (P < 0.01 and P < 0.005, respectively) than the mean of the readings obtained during the 24-h period, but this phenomenon did not occur among the females. Male's mean systolic (129.8 +/- 10.6 vs. 117.1 +/- 9.7 mmHg, P < 0.0001) and diastolic pressures (83.4 +/- 8 vs. 74.9 +/- 7.3 mmHg, P < 0.001) were significantly higher during the working period in relation to those of the female group. Discussing the influence of the kind of work on blood pressure, we came to the conclusion of the existence in our environment of a group of subjects (generally males), presenting high blood pressure values during their working period at the hospital and normal or borderline values during the rest of the day. This should be of interest, since it has been reported that subjects with high workplace blood pressure have an increased risk of hypertension and target-organ damage.

Adult↗
PubMed1994

Evaluation of some pharmacological activities of Eugenia uniflora L.

In view of the extensive use of Eugenia uniflora in folk medicine, different extracts of dried and fresh leaves of the plant were assayed to test its possible pharmacological activities. The infusion of fresh leaves had a highly significant anti-inflammatory effect when administered p.o. to rats 1 h before subplantar injection of carrageenin. The infusion increased the pentobarbital sleeping time and also had an effect on intestinal transit, and had no acute toxic effect. No analgesic or antimicrobial activities were observed with any of the extracts used.

Administration, Oral↗