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Biomedical subjects

J Vilar

Publications and source records attributed to J Vilar.

35 records · Page 2Linked to original sources
PubMed1993

Lack of control by adrenal steroids of oxidative enzymes and Na/K-ATPase development in the rat proximal tubule.

The activities of citrate synthase, 3-oxoacid CoA-transferase, and Na/K-ATPase were determined in the proximal convoluted tubules (PCT) of midcortical nephrons from 16-, 21- and 30-day-old and adult rats. Enzyme microassays based on NAD amplification were run on tubule segments microdissected from lyophilized tissue sections, and the activities were expressed per unit of tissue dry weight. The activities of 3-oxoacid CoA-transferase (+ 155%) and citrate synthase (+ 44%) increased between 16 and 30 days, while no significant change in Na/K-ATPase activity occurred during this period. The results obtained in PCT from subcapsular nephrons were similar. It is concluded that active transport of Na+ coupled to mitochondrial ATP production might be mature in the PCT by the time of weaning, consistent with data on the development of Na+ reabsorption. Since adrenalectomy on day 16 induced no changes in the activities of oxidative enzymes or Na/K-ATPase on day 21 in midcortical or subcapsular PCT, the physiological rise in circulating glucocorticoids, characteristic of the weaning period, does not trigger the development of oxidative enzymes and Na/K-ATPase in the PCT of the developing rat kidney.

Adrenal Cortex Hormones↗
PubMed1993

Relationship between autonomic dysfunction and BP variability in subjects with diabetes mellitus.

Autonomic vagal heart rate (HR) control, office BP and ambulatory BP were examined in 54 diabetic subjects, aged 63 +/- 6 years. Sixteen subjects were insulin-dependent. The HR response to deep breathing (the bradypnoea test) was used to evaluate the vagal HR control, and ambulatory BP was determined by the Spacelabs 5200 system (one determination every 15 minutes, for 24 hours). Twenty-seven subjects had normal office BP (SBP < or = 140 mmHg and DBP < or = 90 mmHg), seven had established hypertension (SBP > or = 160 mmHg and DBP > or = 95 mmHg) and 30 were borderline hypertensives. Over the total group, office systolic/diastolic BP (mean +/- SD) was 142 +/- 20/85 +/- 10 mmg. Systolic/diastolic ambulatory BP was 123 +/- 13/77 +/- 10 mmHg and ambulatory HR was 70 +/- 8 beats/min. Because of the small age range of our subjects, the HR score was not correlated with age (r = 0.19, NS). The HR score was not correlated with the levels of office and ambulatory pressures. In contrast, it was significantly correlated with the variability of ambulatory SBP, whether the variability was defined by the pressure standard deviation, or by the ratio SD/mean value (r = 0.40, P = 0.005 and r = 0.33, P < 0.017, respectively). We suggest that an impairment of the autonomic control in diabetics might induce an increase in variability of SBP. BP variability might play a role in the cardiovascular complications observed in diabetics.

Aged↗
PubMed1992

Administration of oral chloral hydrate to paediatric patients undergoing magnetic resonance imaging.

Sedation is frequently required in children undergoing magnetic resonance imaging (MRI). 172 Paediatric patients (82 female and 90 male, age 42 +/- 26 months, weight 14.7 +/- 5.6 kg) entered an open, non-comparative, prospective study to assess the utilization of oral chloral hydrate. Chloral hydrate syrup (70 mg/ml) was administered 20-30 min prior to the procedure. Effective sedation was reached in 80.3% with an average initial dose of 55 mg/kg and in 93.6% with an average total dose of 65 mg/kg. Significant differences in effectivity were correlated with the dose (54 +/- 11 mg/kg in failure cases versus 66 +/- 16 mg/kg in effective cases; p < 0.05) and diagnosis (effectivity falls to 62.5% and 76.0% in children with medullar tumours and encephalic white matter alterations, respectively; p < 0.01). Average sleep induction time was 30 +/- 19 min, and average duration of sleep was 62 +/- 24 min. Adverse reactions occurred in 4.7%, with nausea, vomiting and stomach pain being the most common side-effects (3.5%). Multivariate statistical analysis selects total dose and age into the discriminant function, with a 100% relative percentage of correct classification. A simple method for optimizing the chloral hydrate dose in children is proposed: the dose in mg/kg is calculated as half the age in months + 50.

Administration, Oral↗
PubMed1992

Ambulatory blood pressure monitoring: a critical review of the current methods to handle outliers.

OBJECTIVES: To examine the methods to handle marginal readings in the analysis of ambulatory blood pressure. DESIGN: Data obtained from automatic ambulatory blood pressure monitoring include several 'outliers', i.e. readings at the frontier of physiologically acceptable ranges. Several methods have been used to handle these readings. We need to know whether using different methods to reject outliers leads to different results in the analysis of the data. If so, then it is important that a common method be used by different authors. METHODS: Ten reported methods to handle outliers were selected and applied to a large set of unpublished blood pressure profiles (Novacor Diasys system). We compared the effects of data rejection by these methods on the mean values and standard deviations (calculated over 24 h, daytime and night-time) of the remaining data. RESULTS: The different methods had quite different effects on the same data set. Depending on the method used, the discarded data varied from 1 to 17% of the total number of readings. Among the rejected data, readings that occurred in the daytime varied from 14 to 56%. Also, 'high-value' outliers varied from 1 to 60% of the rejected data. On average over the total sample, the rejection of outliers had only a small effect on the mean values of blood pressure. In contrast, it may strongly reduce the standard deviation of the readings. CONCLUSION: The study emphasized the need to use a common method to handle outliers in the analysis of ambulatory blood pressure data.

Adult↗
PubMed1992

Milk-stimulated PGE2 production by isolated gastric cells: a possible role in the inhibition of histamine-induced acid secretion.

The effects of a milk diet on gastric acid secretion of rats fed raw bovine milk for 4 days were examined using dispersed gastric cells. Parietal cell acid secretion was estimated by the accumulation of 14C-aminopyrine (AP), an index of secretory function. Basal AP accumulation was significantly increased (60%) by the milk diet. There was a marked upward shift in the dose-response curve of histamine (HA; 10(-8) to 10(-3) M) in milk-fed rats, indicating enhanced sensitivity of parietal cell-H2 receptor to exogenous HA. In contrast, the dose-dependent inhibition of HA-induced AP accumulation by prostaglandin (PG) E2 was significantly reduced, indicating that the parietal cells of milk-fed rats were less sensitive to exogenous PGE2. The PGE2 content of bovine milk was low (less than 20 pg/ml), but the production of endogenous PGE2 by the gastric cells was dramatically increased by the milk diet and exhibited maximal control production rate in the presence of 10 microM arachidonic acid. The increased responsiveness to histamine and the decreased responsiveness to PGE2 indicated that the milk diet induced low histamine and high PGE2 availability in the vicinity of the parietal cell basolateral membrane. This regulation, which involves stimulation of PGE2 production in the gastric mucosa, may underly the inhibition of acid secretion observed in vivo in chronically milk-fed adult rats.

Aminopyrine↗
PubMed1992

Active and passive effects of antihypertensive drugs on large artery diameter and elasticity in human essential hypertension.

The effects of antihypertensive drugs on the large arteries consist of two parts: the passive effect due to the change in pressure and the active effect, the drug action per se. This study proposes a method of dissociating the passive effect from the active effect. The diameter of the arterial artery was determined by the pulsed Doppler method and the pulse wave velocity of the brachioradial artery by mecanography. Arterial compliance was calculated by the Bramwell-Hill formula. Active and passive effects were determined by a logarithmic pressure-diameter model. This model was supported by in situ direct measurements of blood pressure and diameter in a segment of the femoral artery in dogs. Six drugs, cadralazine, ketanserin, medroxalol, nitrendipine, captopril, and isosorbide dinitrate, administered orally, were tested in 70 essential hypertensive patients. For all drugs, the pressure reduction induced a passive decrease in arterial diameter (p less than 0.02 to p less than 0.01). Cadralazine actively decreased arterial diameter (p less than 0.01), ketanserin had no active effect on diameter, and medroxalol, nitrendipine, captopril, and isosorbide dinitrate actively increased arterial diameter (p less than 0.05, p less than 0.01, p less than 0.01, and p less than 0.01, respectively). For all drugs, the pressure reduction also induced a passive increase in arterial compliance (p less than 0.05 to p less than 0.01). However, only nitrendipine, captopril, and isosorbide dinitrate actively increased arterial compliance (p less than 0.01, p less than 0.05, and p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Ambulatory blood pressure is still elevated in treated hypertensive diabetic subjects compared with untreated diabetic subjects with the same office blood pressure.

Ambulatory blood pressure, ABP, was determined every 15 min for 24 h (Spacelabs 5200 system) in 16 hypertensive diabetic subjects treated for high blood pressure. Office blood pressure (OBP) in these subjects (systolic BP greater than 160 mmHg and diastolic BP greater than 95 mmHg before treatment) had been reduced by treatment to the borderline range (systolic less than or equal to 160 mmHg and/or diastolic less than or equal to 95 mmHg). Sixty-five diabetic subjects with normal or borderline OBP were included as controls. The two groups had the same age (58 +/- 10 yrs in both groups), duration of diabetes (15 +/- 9 yrs), 24 hr microalbumin, and included the same percentage of subjects with moderate neuropathy (36% and 29%, NS). The two groups had the same OBP (138 +/- 16 mmHg and 140 +/- 16 mmHg systolic, NS, 84 +/- 9 mmHg and 84 +/- 13 mmHg diastolic, NS). In contrast, ambulatory BP was significantly higher in the treated group, when compared with the controls (123 +/- 13 mmHg and 133 +/- 23 mmHg systolic, P less than 0.025, 77 +/- 7 mmHg and 84 +/- 16 mmHg diastolic, P less than 0.015). The difference was significant both in daytime and in nighttime, and was more significant in nighttime (11 mmHg systolic, P less than 0.02, 9 mmHg diastolic, P less than 0.004) than in daytime (9 mmHg systolic, P less than 0.05 and 5 mmHg diastolic, P less than 0.05). Ambulatory heart rate was also significantly higher in the treated group, but only in daytime (7 b/min difference, P less than 0.02). The study demonstrated the need to survey and investigate ABP in treated hypertensive diabetic subjects.

Adult↗
PubMed1991

High density barium sulphate as an MRI oral contrast.

High density barium sulphate suspension was investigated as an oral contrast on MRI. On 30 consecutive subjects, the stomach (in all cases) and the two first portions of the duodenum (in 21 cases) were filled with the suspension. This oral contrast behaved as a negative contrast, being hypointense on all pulse sequences (spin-echo T1-weighted, spin-echo T2-weighted and STIR). This characteristic is probably due to the low proton density of the suspension (260 +/- 40). Since barium sulphate is inexpensive, harmless and available on all radiologic departments, it is recommendable in MRI studies of the liver and head of the pancreas.

Administration, Oral↗
PubMed1991

[Intrinsic (isobaric) effect of essential hypertension on visco-elastic properties of the brachial artery].

The purpose of this study was to estimate the effect of hypertension on the visco-elastic properties of the brachial artery in man. Seventy-five subjects including 23 with normal blood pressure (group N, PN = 95 +/- 7 mmHg, P designates the arterial mean pressure, P = DBP + (SBP-DBP)/3) and 52 with essential hypertension (group H, PH = 122 +/- 12 mmHg) participated to this study. We measured the diameter of the brachial artery (D) by the pulsed Doppler method, the brachial-radial pulse wave velocity (PWV) by the mecanographic method, and calculated the arterial compliance (C) by the Bramwell-Hill formula. A nonlinear model was used to calculate compliance and pression at any given pressure, in particular at PN or PH. We obtained the following results: [table; see text] Passive (pressure-induced) effect was obtained by comparing D(PH) to D(PN) and C(PH) to C(PN). Isobaric effect of hypertension was estimated by comparing D(PH) and C(PN) between the N and H groups. We concluded that hypertension actually induces a decrease in compliance. However, arterial diameter is increased in hypertension. The increase in diameter appears as a compensatory effect, without which the reduction in compliance would be more nocive to the circulatory system.

Adult↗
PubMed1989

Lipoma of the liver: US, CT, and MRI appearance.

A case of hepatic lipoma is reported. Since the sonographic (US), computed tomographic (CT), and magnetic resonance imaging (MRI) findings are characteristic, we believe more aggressive diagnostic procedures are not necessary.

Female↗
PubMed1983

Hemangioma of the kidney.

A case of hemangioma in the lower pole of the right kidney is reported. Relapsing hematuria and a urographic filling defect were the principal findings. A vascular mass of thick uniform vessels with rapid shunting of contrast medium into the vein was seen in arteriography. The histologic appearance was highly dilated vessels with well-framed walls. Lower heminephrectomy was successfully performed. The main features of this rare tumor are discussed.

Female↗
PubMedDate not supplied

Brodie abscess: MR imaging appearance in 10 patients.

The magnetic resonance (MR) imaging features of Brodie abscess have not yet been fully evaluated. Ten patients with Brodie abscess, eight of long bone and two of vertebra, were studied with MR imaging. Long bone abscess had a characteristic "target" appearance with four layers: (a) a center with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR (short-inversion-time inversion recovery) images, (b) an inner ring isointense to muscle on T1-weighted images and with high signal intensity on T2-weighted and STIR images, (c) an outer ring hypointense on all images, and (d) a peripheral halo hypointense on T1-weighted images. In six of eight cases, a soft-tissue mass was found. The two vertebral abscesses had a less specific appearance, with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR images. Only the peripheral halo was clearly identified in both cases.

Abscess↗
PubMedDate not supplied

Regional lymphadenopathies in patients with renal calculi: analysis with ultrasound and MRI.

Thirty-nine patients with renal calculi were retrospectively studied with magnetic resonance (MR) imaging and an ultrasound (US). All patients were examined as part of a research project for imaging evaluation of complications of extracorporeal shock wave lithotripsy. Twelve of the patients showed lymph node enlargement in the retroperitoneal perivascular space. Adenopathies were visualized by MR imaging but not with US: The presence of large lymph nodes was associated with urinary, renal parenchymal, or stone infection. When large lymph nodes are found in the retroperitoneal perivascular space in patients with lithiasis, urinary tract infection must be assumed as the cause of these adenopathies.

Female↗
PubMedDate not supplied

Lesion/fat intensity ratio in MR characterization of hepatic masses.

On T2-weighted spin echo images, lesion/liver intensity ratios can be used to accurately distinguish hepatic cavernous hemangioma from malignant lesions. However, since patients with focal liver lesions may present diffuse liver disease, this relationship can be inaccurate. We studied 91 hepatic lesions to compare the value of lesion/liver and lesion/fat ratios in the differential diagnosis of liver lesions. In doubtful cases the use of lesion/fat intensity ratio can be used to improve accuracy in the diagnosis of liver lesions. The combination of both ratios into a single diagnostic index gave a correct classification of malignant versus hemangioma in 92.3% of the cases.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Effect of glucocorticoids on mitochondrial oxidative enzyme and Na-K-ATPase activities in the rat proximal tubule and thick ascending limb of Henle.

The activities of three mitochondrial oxidative enzymes (citrate synthase, 3-ketoacid-CoA transferase, beta-hydroxyacyl-CoA dehydrogenase) and Na-K-ATPase were microassayed in isolated segments of the rat proximal convoluted tubule (PCT) and medullary thick ascending limb of the loop of Henle (mTAL). The effects of adrenalectomy (ADX) and ADX plus exogenous glucocorticoids were analyzed. The hormonal replacement was daily injections of dexamethasone (10 micrograms/100 g body weight/24 h) for 5 days. ADX lowered the activity of all oxidative enzymes studies in the mTAL, but not in the PCT and led to a decrease in Na-K-ATPase in both nephron segments. Dexamethasone restored the normal level of oxidative enzymes and Na-K-ATPase in the mTAL and of Na-K-ATPase in the PCT. We conclude that the activities of citrate synthase, 3-ketoacid-CoA transferase and beta-hydroxyacyl-CoA dehydrogenase and of Na-K-ATPase are coordinately regulated in the mTAL and that glucocorticoids are essential for the long-term regulation of these enzyme activities in this nephron segment. In contrast, the activities of mitochondrial oxidative enzymes are not influenced by glucocorticoids in the PCT. This study presents the first evidence for a cell-specific regulation by glucocorticoids of oxidative metabolism in the nephron of adult rat kidney.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMedDate not supplied

[Sporadic non-A, non-B hepatitis in Argentina. The responsibility of the hepatitis E virus?].

Sporadic non A, non B hepatitis non related to blood transfusions or parenteral exposure is present in India and various countries of southeast Asia and Africa. We present the experience in a northeastern region of Argentina from January 1987 to September 1990. During this period twenty one patients where identified with acute hepatitis without serologic evidence of infection with HAV, HBV, HCV, toxoplasmosis, infectious mononucleosis nor clinical evidence of Herpes virus infection. Clinic and biochemical parameters were analyzed and showed a considerable elevation of transaminases and cholestasis. Of the 21 patients diagnosed as having acute non A non B hepatitis of probable enteric transmission (NANBE), 10 where male and 11 female. Mean age was 24.7 years. In all cases the disease was self limited and follow up during more than one year after the acute episode did not demonstrate signs of reactivation nor evidence of chronicity.

Acute Disease↗