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Biomedical subjects

M Aparicio

Publications and source records attributed to M Aparicio.

At least 37 records · Page 2Linked to original sources
PubMed1999

The extent of the Aznalcóllar pyritic sludge spill and its effects on soils.

This paper presents some initial results from the Instituto Tecnológico Geominero de España's (ITGE) study of the Aznalcóllar mine spill. The spatial distribution of the pyritic sludge released was surveyed by using remote sensing data, aerial photography, and more than 700 field measurements on the sludge thickness. Initial estimation of the extent of the sludge was provided by radar data. Maps at 1:10,000 scale, drawn on the basis of field data and interpretation of aerial photos, show the distribution of the sludge, divided into 168 subsections on the basis of average thickness. GIS analysis provided estimates of the area and volume of the sludge. Three approaches were followed in order to survey the effects of the spill on the Guadiamar river alluvial soils: (1) Mineralogical and chemical characterization of the sludge and its evolution until its removal. Alteration products of the pyritic sludge were also analyzed. (2) Determination of geochemical background of soils in the Guadiamar river basin, in order to establish the content of heavy metals and other elements in the soil before the spill. (3) Assessment of the sludge effect on soils caused by the acid water and the deposited sludge, by comparison of the heavy metal content of soil under the sludge layer with that of background soil. Finally, an airborne multispectral survey was carried out over the Aznalcóllar-Doñana area to evaluate its efficiency for monitoring soil condition during and after sludge removal.

Accidents, Occupational↗
PubMed1999

Outcome of nutritional status and body composition of uremic patients on a very low protein diet.

Concern has been raised about the nutritional adequacy of a very low protein diet (VLPD). Monthly clinical evaluation by a physician and dietitian and quarterly dietary records, anthropometric measurements, blood testing, and dual energy X-ray absorptiometry (DEXA) were used to assess the course of nutritional status for 1 year in 10 clinically stable patients (six men, four women; age, 57.1 +/- 9.3 years) with advanced chronic renal failure (mean glomerular filtration rate, 13.2 +/- 4.8 mL/min/1.73 m(2)). These patients received a VLPD providing 0.3 g/kg/d of protein and were supplemented with amino acids and ketoanalogues. Conventional nutritional markers remained unchanged after 1 year of the VLPD. However, during the same period, whole-body DEXA showed a significant decrease in lean tissue from 46.2 +/- 10.2 to 45.0 +/- 9. 8 kg (P < 0.02); limb-trunk lean tissue ratio was reduced from 0.86 +/- 0.12 to 0.82 +/- 0.12 (P < 0.02), total-body fat increased from 20.0 +/- 6.9 to 21.4 +/- 7.0 kg (P < 0.05), and the percentage of total-body fat increased from 29.2% +/- 8.7% to 31.7% +/- 8.8% (P < 0.03). These different modifications occurred abruptly during the first 3 months, then stabilized or slightly improved thereafter. These mild changes do not appear to be deleterious given the favorable long-term outcome of these patients, even after they began treatment by dialysis or after renal transplantation.

Absorptiometry, Photon↗
PubMed1999

Thymoma associated with myasthenia gravis and minimal lesion nephrotic syndrome.

A nephrotic syndrome has been observed rarely in association with thymoma. In most of the reported cases, it occurs when the thymoma is in remission; histological examination generally shows minimal change disease. We report a case of a 43-year-old man presenting with minimal lesion nephrotic syndrome at the time of the diagnosis of thymoma and myasthenia gravis, which persists despite remission of the thymoma. The role of a disorder of T-cell function and of circulating cytokines is discussed.

Adult↗
PubMed1999

Reduced parathyroid functional mass after successful kidney transplantation.

BACKGROUND: Chronic uremia is responsible for secondary hyperparathyroidism (HPT II). Parathyroid secretion usually tends to normalize after kidney transplantation (KT), but the parameters of the reversibility of HPT II remain poorly defined, particularly the intrinsic mechanisms underlying the improvement of parathyroid function. METHODS: The kinetic functional parameters of the ionized calcium (iCa)/parathormone (PTH) relationship curve were studied in 11 patients with mild to moderate HPT II one and six months after successful KT. Hypercalcemia and hypocalcemia were induced, respectively, by CaCl2 and Na2-ethylenediaminetetraacetic acid (Na2-EDTA) infusions. RESULTS: The mean glomerular filtration rate remained stable during follow-up. Basal PTH decreased from 195 +/- 54 pg/ml before KT to 70 +/- 12 pg/ml six months later (P < 0. 005). During the tests, mean PTH levels decreased significantly between the two measured times for all iCa levels, indicating an improved parathyroid function. An analysis of the kinetic parameters of the curves showed significant decreases of the mean maximal and minimal PTH levels, respectively, from 340 +/- 91 to 220 +/- 30 pg/ml (P = 0.03) and from 25 +/- 6 to 15 +/- 5 pg/ml (P = 0.005). On the other hand, no change was noted in the parathyroid-cell calcium-sensitivity parameters (slope, set point) assessed using two different approaches, either the entire curve or the limited calcium-mediated suppression curve. CONCLUSION: Improvement of the parathyroid function between the first and sixth months post-KT seems mainly attributable to a reduction of the parathyroid functional mass.

Adult↗
PubMed1999

Effect of the cyclo-oxygenase blocker ibuprofen on cerebral blood volume and cerebral blood flow during normocarbia and hypercarbia in newborn piglets.

Indomethacin modifies baseline cerebral haemodynamics and metabolism, as well as vasomotor adaptive responses. However, the significance of arachidonic acid metabolites in the regulation of cerebral circulation remains unclear. A study was made of the effect of inhibition of the cyclo-oxygenase pathway on baseline cerebral haemodynamics and CO2-induced vasodilation using the more specific cyclo-oxygenase blocker ibuprofen in a neonatal pig model. Two methods were used: radiolabelled microspheres to measure cerebral blood flow and near infrared spectroscopy to calculate absolute changes in cerebral blood volume. The relationship between CO2-induced changes in these two haemodynamic parameters was evaluated. Fifteen newborn piglets <7 d old received an i.v. infusion of either ibuprofen (30 mg/kg) (IB group, n = 8) or saline (control group, n = 7). Cerebral blood flow and absolute changes in cerebral blood volume were measured while the piglets were breathing room air at baseline and 30 min after infusion of ibuprofen or saline, and 15 min and 30 min after inducing hypercarbia. Global and regional cerebral blood flow (ml/hg/min) and absolute changes in cerebral blood volume (ml/hg) did not vary between baseline and 30 min after infusion of ibuprofen or saline. During hypercarbia, global and regional cerebral blood flow and absolute changes in cerebral blood volume increased significantly in both the ibuprofen and control groups (p < 0.01). The mean percentage increases in blood flow and blood volume at each measurement were almost identical, with approximately 90% of the increase in both parameters occurring after 15 min of hypercarbia, then reaching a plateau. However, we found no agreement between cerebral blood flow changes and absolute changes in cerebral blood volume. We conclude that ibuprofen did not alter either baseline cerebral circulation or physiological CO2-induced vasodilation in newborn pigs. We speculate that hypercarbic cerebral vasodilation could be caused either by mediators other than the cyclo-oxygenase metabolites of arachidonic acid or by a direct effect on vessel walls.

Analysis of Variance↗
PubMed1999

Nutritional status of haemodialysis patients: a French national cooperative study. French Study Group for Nutrition in Dialysis.

BACKGROUND: Despite the severity and the prognosis value of undernutrition in haemodialysed patients, no large study is available as yet in Europe. Hence, this French National Cooperative Study aimed to determine the prevalence of undernutrition and its relationship to dialysis efficacy. METHODS: Nutritional status was determined in 7123 patients (i.e. one-third of the French haemodialysis population) using body mass index (BMI), predialysis haemoglobin, albumin, pre-albumin, cholesterol, and also normalized protein catabolic rate (nPCR) and lean body mass (LBM) calculated from pre- and postdialysis urea and creatinine. Dialysis treatment was estimated from weekly dialysis time and KtV determination. RESULTS: Dialysis time was 12.4+/-2.7 h/week and KtV 1.36+/-0.36. BMI was below 20 kg/m2 in 24% and the observed/expected LBM ratio below 90% in 62%. Albumin, pre-albumin and nPCR were below the high-risk thresholds of 35 g/l, 300 mg/l and 1g/kg/day in 20%, 36% and 35% of patients, respectively. Pre-albumin was the most representative nutritional parameter. Albumin, pre-albumin and LBM correlated with nPCR. A dialysis time above 12 h/week was associated with higher BMI, albumin, pre-albumin and LBM. LBM was higher in patients with a KtV value >1.1. CONCLUSION: This study showed life-threatening undernutrition in 20-36% of the studied population, according to nutritional parameters. Protein intake (estimated by nPCR) and dialysis efficacy (estimated by dialysis time and KtV) appeared to be major determinants of nutritional status in this population.

Adult↗
PubMed1999

Bone mass and dynamic parathyroid function according to bone histology in nondialyzed uremic patients after long-term protein and phosphorus restriction.

One year of a very low protein diet (VLPD) can reverse secondary hyperparathyroidism in uremic patients. We studied bone histology, bone mineral density (BMD), and dynamic parathyroid function (calcium/PTH curves) in 16 nondialyzed patients with advanced renal failure who had been receiving a VLPD for a mean of 5 yr (mean protein intake, 0.34 +/- 0.12 mg/kg x day; mean phosphorus intake, 8.2 +/- 2.1 mg/kg x day) and daily supplementation with essential amino acids and their ketoanalogs (1000 IU vitamin D2 and 1-2 g calcium carbonate). Three patients exhibited a high bone formation rate (BFR), 7 patients had normal bone remodeling, and 6 patients had a low BFR, including 2 with osteomalacia and 4 with adynamic bone disease without aluminum overload. A longer diet duration and lower caloric intake were associated with low BFR. More than half of the patients exhibited moderate or severe osteoporosis at the appendicular skeleton. The t score of femur BMD explained 65% of the BFR variance. Patients with a low BFR had a dynamic parathyroid function similar to that of patients with a normal BFR, except they had a lower capacity to buffer a calcium load, whereas patients with a high BFR had a higher basal PTH/maximum PTH and a steeper calcium/PTH curve slope; the calcium set-point was identical in the three groups.

Adult↗
PubMed1998

Effects of low-protein diet on carbohydrate metabolism and energy expenditure.

Low-protein diets (LPD), which are prescribed for uremic patients to slow the progression of chronic renal failure, theoretically may exacerbate disorders of carbohydrate metabolism that are frequently observed in these patients because increased carbohydrate rations are required to maintain a sufficient caloric intake. No such exacerbation actually occurs. Glucose tolerance has been shown to improve after 3 months of a diet affording .3 g protein/kg body weight supplemented with essential amino acids and ketoanalogs with carbohydrates accounting for 67% of the total energy intake. Hyperinsulinemic euglycemic clamp studies show that this amelioration is linked with an increase in insulin sensitivity, which is also observed in uremic diabetic patients on this diet. The improvement in glucose tolerance involves the insulin sensitivity of endogenous glucose production, glucose oxidative disposal, and its nonoxidative disposal. Besides these effects, LPD increases the metabolic clearance rate of insulin and causes blood insulin levels to decrease. LPD's low acid load and phosphorus content, the reduced synthesis of uremic toxins derived from alimentary protein, or both may explain these effects, which are indirectly protective against atherosclerosis. However, the significant increase in resting energy production after 3 months on LPD justifies strict monitoring of nutritional status and caloric intake.

Basal Metabolism↗
PubMed1998

Erythropoietin can deteriorate glucose control in uraemic non-insulin-dependent diabetic patients.

Two patients with non-insulin-dependent diabetes mellitus (NIDDM) and moderate chronic renal failure experienced a worsening of glycaemic control when recombinant human erythropoietin (r-HuEPO) was introduced, leading to insulin therapy. A 71-year-old woman with a 20-year history of NIDDM had presented histologically documented diabetic nephropathy for 2 years during which glucose control was stabilized by a diet and glibenclamide 10 mg. In the 6 months following introduction of r-HuEPO, hyperglycaemic symptoms developed, and HbA1C increased from 8.9% to 12.3%. During this period, no intercurrent events occurred, except epistaxis due to accelerated hypertension one month after r-HuEPO was started. A 62-year-old man had a 15-year history of NIDDM, with proliferative retinopathy, macroproteinuria and chronic renal failure for 4 years. The day after the first injection of r-HuEPO, capillary glucose level rose dramatically. In both of these cases, antihypertensive treatment was increased and insulin introduced. The role of r-HuEPO in hyperglycaemia was probable in the first case and highly probable in the second. Reports about the effects of r-HuEPO on glucose metabolism in uraemic patients are conflicting. Short- and long-term effects can differ, although long-term benefit is likely. The fact that our patients were not dialized may have been important. Clinicians should be aware that glucose control may deteriorate with r-HuEPO, requiring some uraemic NIDDM patients to undergo insulin therapy.

Aged↗
PubMed1998

[Scleroderma renal crisis. 7 cases and review of the literature].

We report a series of seven patients who had scleroderma renal crisis. Their primary clinical and laboratory features along with the details of their management were compared with those of similar cases from the literature. The seven patients died within one to four months of the diagnosis with a pattern of acute renal failure, left ventricular failure and malignant hypertension. Histopathologic examination was performed in four of the patients, in two of whom it revealed thickening of the wall of the interlobular arteries related to the scleroderma, and in the other two patients nonspecific lesions of malignant hypertension. This histopathologic particularity led us to propose, on the basis of multiple renal biopsies performed in patients with scleroderma, a lesion chronology of the kidney in patients with scleroderma. Nevertheless, the triggering factors and pathophysiologic mechanisms of scleroderma renal crisis remain unclear and its prognosis is severe. Early treatment with angiotensin-converting enzyme inhibitors and other vasodilatators administered intravenously can prevent death and dialysis.

Acute Kidney Injury↗
PubMed1997

[Spontaneous rupture of the esophagus (Boerhaave syndrome) in a patient with scleroderma treated by continuous ambulatory peritoneal dialysis].

Esophageal involvement is a common situation found in 50 to 80% of patients with scleroderma, but Boerhaave's syndrome is rare in this context. The authors report the first case of spontaneous esophageal rupture occurring in a chronic renal failure patient treated by continuous ambulatory peritoneal dialysis. In this observation, sclerodermal esophageal dyskinesia, chronic renal failure which is a classical cause of vomiting and the peritoneal dialysis which play an increasing role in the intraabdominal pressure are potential contributing factors to Boerhave's syndrome. In such patients presenting risk factors, even if they are asymptomatic, it seems reasonable to propose esophageal explorations with manometry or/and endoscopy looking for dyskinesia or other complications of gastro-esophageal reflux.

Esophageal Diseases↗