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Biomedical subjects

S De Marchi

Publications and source records attributed to S De Marchi.

At least 37 records · Page 2Linked to original sources
PubMed1996

Risk factors for vascular disease and arteriovenous fistula dysfunction in hemodialysis patients.

Vascular access dysfunction is an important cause of morbidity for dialysis patients and a major contributor to hemodialysis cost. Thrombosis is a leading cause of vascular access failure, and usually results from stenotic lesions in the venous outflow system. This study was designed to explore the impact of serum levels of various risk factors for thrombosis and accelerated fibrointimal hyperplasia on progressive stenosis, and the subsequent thrombosis of hemodialysis fistula. A cross-sectional and 2-yr prospective pilot study was performed in 30 nondiabetic hemodialysis patients with primary arteriovenous fistula. Venous dialysis pressure, urea recirculation, color Doppler sonography, and angiography were used to monitor vascular access patency. Eleven patients (37%) developed a progressive stenosis in the venous circuit, which was complicated by thrombosis in three patients. Compared with the patients without fistula dysfunction, these patients had higher serum levels of monocyte chemoattractant protein-1 and interleukin-6, two cytokines that regulate the proliferation of vascular smooth muscle cells, which is the key mechanism in the pathogenesis of fistula stenosis. In addition, they had hyperinsulinemia, hyperlipidemia, and increased plasma levels of two hemostasis-derived risk factors for thrombosis: plasminogen activator inhibitor type 1 and factor VII. Monocyte chemoattractant protein-1, interleukin-6, plasminogen activator inhibitor type 1, factor VII, triglycerides, and the ratios for cholesterol/HDL-cholesterol, apolipoprotein (apo) A-I/ apo C-III, apo A-I/apo B, and glucose/insulin were independent predictors of fistula dysfunction. This study demonstrates the influece of cytokines, hemostasis-derived vascular risk factor, hyperinsullnemia, and abnormallties of lipids and apolipoproteins on primary fistula survival. The assessment of these factors might be useful for the identification of the patients at risk of fistula stenosis and thrombosis.

Aged↗
PubMed1996

Correlation between peripheral hemodynamic changes and left ventricular diastolic function in hypertensive patients treated with urapidil.

We evaluated the modifications induced by chronic treatment with an alpha 1-adrenolytic hybrid drug, urapidil, on the hemodynamic parameters in peripheral artery and left ventricle diastolic function. Fifteen mild to moderate essential hypertensive patients (13 men, 2 women; mean age 42 years, range 32-54 years) received urapidil (60 mg b.i.d.) for 6 months. Peripheral hemodynamic and cardiac parameters were evaluated by duplex scanner, coupled with a plethysmographic method, basally (T0) and after 6 weeks' (T1) and 6 months' treatment (T2). Mean blood pressure (BP) showed a reduction after 6 weeks of -9.07 mm Hg (confidence intervals [CI] 95%: -9.21; -8.92; P < 0.01), which was maintained after 6 months (-8.21 mm Hg, CI 95%: -8.97; -7.43; P < 0.01), while no significant change was seen in heart rate. Compliance showed highly significant changes after both 6 weeks (+1.073 dyn-1.cm4.10(-7), 95% CI: +0.965; +1.181, P < 0.001) and 6 months (+0.933 dyn-1.cm4. 10(-7), 95% CI: +0.903; +0.963, P < 0.001), as well as characteristic impedance (T1:-16.689 dyn.s.cm-5/10(2), 95% CI: -16.914; -16.463 P < 0.001; T2: -15.98 dyn.s.cm-5. 10(2), 95% CI: -18.186; -13.784; P < 0.001) and forearm resistances (T1: -26.153 mm Hg.ml-1.s, 95% CI: -34.553; -17.753, P < 0.01; T2: -43.587 mm Hg.ml-1.s, 95% CI: -52.711; -34.464, P < 0.01). Similarly, we have recorded a similar change in left ventricular end-diastolic posterior wall thickness (T1: -1.067 mm, 95% CI: -1.099; -1.035, P < 0.01; T2: -2.866 mm, 95% CI: -3.044; -2.688, P < 0.01), end-diastolic interventricular septum thickness (T1: -0.921 mm, 95% CI: -1.511; -0.289, P < 0.05; T2: -2.711 mm, 95% CI: -3.211; -2.199, P < 0.01), end-diastolic volume (T1: +6.4 ml, 95% CI: +6.343; +6.456, P < 0.01; T2: +19.867 ml, 95% CI: +18.564; +21.170, P < 0.01), and mass/volume index (T1: -0.11, 95% CI: -0.118; -0.101, P < 0.01; T2: -0.218, 95% CI: -0.221; -0.217, P < 0.01). Changes in arterial compliance have shown a statistically significant correlation with changes in mass/volume index (r = -0.468; P < 0.03), end diastolic volume (r = 0.501; P < 0.02), as well as left ventricle rapid filling phase (r = 0.426; P < 0.05) and left ventricle end diastolic posterior wall thickness (r = -0.478, P < 0.03). Our results suggest that the antihypertensive efficacy of urapidil coupled with the restoration of the dumping function of the large arteries, and the reduced activation of reflex sympathetic activation, may play a considerable role among the mechanisms allowing the regression of the functional modifications affecting the left ventricular diastole.

Adult↗
PubMed1995

Micro- and macrocirculatory, and biohumoral changes after a month of physical exercise in patients with intermittent claudication.

We studied 15 subjects with intermittent claudication, classed as stage II according to Leriche-Fontaine. The patients were subjected to laser Doppler flowmetry, strain gauge plethysmography, Doppler velocimetry, and blood sampling, in basal conditions and after one month of physical training. Symptom-free walking distance at the end of the training period showed a significant increase, while there was no major change in maximal walking distance or the Windsor index. Laser Doppler flowmetry showed no significant change in cutaneous blood flow at rest, after the month of physical training. On the other hand, strain gauge plethysmography showed a significant decrease in rest flow at the end of the training period, while peak flow of postischemic hyperemia did not change appreciably. Biohumoral evaluations showed a significant decrease of white blood cell count, triglycerides and uric acid. Platelet count, prothrombin time, aPTT and plasminogen were unchanged. On the other hand, we recorded a small, but significant, rise of fibrinogen. Our study confirmed the importance of scheduled physical activity in the patient with intermittent claudication, showing that clinical improvement is not accompanied by an increase in the circulatory reserve. The unchanged levels of plasminogen suggest that the fibrinolytic activity does not vary significantly after a course of physical exercise.

Aged↗
PubMed1994

Changes induced by nicardipine slow release in forearm and myocardial hemodynamics of subjects with essential hypertension.

OBJECTIVE: To evaluate the modifications induced by chronic treatment with a new formulation of nicardipine (slow release) on the hemodynamic parameters in peripheral artery and left ventricle diastolic function. MATERIALS AND METHODS: Ten mild to moderate essential hypertensive male patients (mean age 42 years, range 32-54 years) received nicardipine slow release (40 mg b.i.d.) for six months. Peripheral hemodynamic and cardiac parameters were evaluated by duplex scanner, coupled with a plethysmographic method, basally (T0) and after 1 (T1) and 6 months' treatment (T2). RESULTS: Blood pressure showed a significant reduction after 1 month (mean blood pressure 109 +/- 2 vs 124 +/- 3 mmHg, M +/- SE, p < 0.001), which was maintained after 6 months (mean blood pressure 112 +/- 3 mmHg, p < 0.001), while heart rate showed only a slight, non-significant increase. There were highly significant changes in distensibility (0.29 +/- 0.02 vs 0.16 +/- 0.01 s2.cm-2, T2 vs T0, p < 0.001), characteristic impedance (55 +/- 3 vs 78 +/- 3 dyn.s.cm-5.10(2), T2 vs T0, p < 0.001) and local resistances (71 +/- 5 vs 118 +/- 4 mmHg.ml-1. s, T2 vs T0, p < 0.001) in the brachial artery, and also in left ventricle posterior wall diastolic thickness (10.2 +/- 0.4 vs 11.5 +/- 0.3 mm, T2 vs T0, p < 0.05), end diastolic volume (127 +/- 3 vs 109 +/- 3 ml, T2 vs T0, p < 0.01) and mass/volume index (1.21 +/- 0.03 vs 1.35 +/- 0.03, p < 0.05). CONCLUSIONS: The antihypertensive efficacy of nicardipine slow release, with only two daily administrations, allows the restoration of the dumping function of the large arteries, and the regression of the functional modifications affecting the left ventricular diastole.

Adult↗
PubMed1993

Renal tubular dysfunction in chronic alcohol abuse--effects of abstinence.

BACKGROUND: Alcohol abuse may be accompanied by a variety of disorders of electrolyte and acid-base metabolism. The role of the kidney in the pathogenesis of these disturbances is obscure. We sought to evaluate the alcohol-induced abnormalities of renal function and improvement during abstinence and to assess the relation between renal dysfunction and electrolyte and acid-base disorders. METHODS: We measured biochemical constituents of blood and renal function before and after four weeks of abstinence in 61 patients with chronic alcoholism who had little or no liver disease. RESULTS: On admission, 18 patients (30 percent) had hypophosphatemia and hypomagnesemia, 13 patients (21 percent) had hypocalcemia, and 8 patients (13 percent) had hypokalemia. Twenty-two patients (36 percent) had a variety of simple and mixed acid-base disorders. Twenty of these patients had metabolic acidosis, and among them, 80 percent had alcoholic acidosis. A wide range of defects in renal tubular function, with normal glomerular filtration rate, were detected in these patients. The defects included decreases in the threshold and maximal reabsorptive ability for glucose (38 percent of patients) and in the renal threshold for phosphate excretion (36 percent); increases in the fractional excretion of beta 2-microglobulin (38 percent), uric acid (12 percent), calcium (23 percent), and magnesium (21 percent); and aminoaciduria (38 percent). Seventeen patients (28 percent) had a defect in tubular acidification, and five an impairment in urinary concentrating ability. Urinary excretion of N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase were increased in 41 and 34 percent of patients, respectively. The abnormalities of blood chemistry and renal tubular function disappeared after four weeks of abstinence. CONCLUSIONS: Transient defects in renal tubular function are common in patients with chronic alcoholism and may contribute to their abnormalities of serum electrolyte and blood acid-base profiles.

Acid-Base Imbalance↗
PubMed1993

Hemodynamic changes induced by cilazapril and atenolol during isometric stress in hypertensive patients.

We studied 16 mild to moderate essential hypertensive patients (14 male, 2 female; mean age 45 years, range 34-55 years) in order to investigate the effects of an ACE inhibitor, cilazapril (5 mg o.d.) and a selective beta-blocker, atenolol (100 mg o.d.) on the hemodynamics of the brachial and carotid arteries after an isometric stress test with a handgrip. Both drugs caused a statistically significant decrease in blood pressure after three months' treatment, but only cilazapril reduced it after the first dose. Heart rate was reduced only by atenolol (61 +/- 3 vs 71 +/- 3 bpm; p < 0.01). Changes in forearm compliance and characteristic impedance showed a difference statistically significant both for acute test and after three months of treatment. The increase in blood pressure during handgrip did not differ appreciably between the two treatment groups. On the contrary, after handgrip only cilazapril caused a significant increase of the reactive hyperemia.

Adult↗
PubMed1992

Relief of pruritus and decreases in plasma histamine concentrations during erythropoietin therapy in patients with uremia.

BACKGROUND: The pathophysiologic aspects of pruritus in patients with chronic renal insufficiency are poorly understood, and there is no universally effective treatment. The improvement of pruritus in several patients receiving erythropoietin therapy raised the possibility that erythropoietin affects uremic pruritus directly. METHODS: We undertook a 10-week placebo-controlled, double-blind, crossover study in a group of patients receiving hemodialysis who had severe pruritus, to investigate the effects of recombinant human erythropoietin on their pruritus and plasma histamine levels. Twenty patients with uremia, of whom 10 had severe pruritus and 10 did not, received erythropoietin (36 units per kilogram of body weight three times weekly) and placebo in random order, each for five weeks. The severity of pruritus was scored weekly, and plasma histamine levels were measured at the beginning and end of each five-week period. RESULTS: Eight of the 10 patients with pruritus had marked reductions in their pruritus scores during erythropoietin therapy. The mean (+/- SE) pruritus score decreased from 25 +/- 3 to 6 +/- 1 in these patients. The pruritus returned within one week after the discontinuation of therapy. The improvement was not related to the change in hemoglobin level. These eight patients were successfully treated again with low doses of erythropoietin (18 units per kilogram three times weekly), and the effect has persisted for six months. The patients with pruritus had elevated plasma histamine concentrations (20.7 +/- 2.7 nmol per liter), as compared with the patients without pruritus (4.2 +/- 0.6 nmol per liter; P less than 0.001) and normal subjects (2.1 +/- 0.2 nmol per liter; P less than 0.001). Therapy with erythropoietin induced a decrease in plasma histamine concentrations in both groups of patients with uremia, and recurrences of pruritus after the discontinuation of erythropoietin were accompanied by increases in plasma histamine concentrations. CONCLUSIONS: Erythropoietin therapy lowers plasma histamine concentrations in patients with uremia and can result in marked improvement of pruritus.

Double-Blind Method↗
PubMed1992

Bardet-Biedl syndrome and cystinuria.

An unusual association of Bardet-Biedl syndrome with cystinuria was described in one patient. A 21-year-old male was admitted to hospital because of renal failure, severe deterioration of visual acuity, polydactyly, brachydactyly, and mental retardation. Laboratory investigations revealed a serum creatinine of 292 mumol/L (3.3 mg/dL) and a GFR of 25 mL/min per 1.73 m2. Quantitative ion exchange chromatography demonstrated an increased urinary excretion rate of cystine, lysine, arginine, and ornithine. The ophthalmologic examination showed a severe atypical retinal dystrophy. Visual acuity was severely deteriorated and the patient could only count the examining physician's fingers. The patient had been previously evaluated at the age of 7 years for polyuria, polydipsia, and growth failure. His workup at that time demonstrated nephrogenic diabetes insipidus, normal GFR, and a urinary amino acid pattern consistent with the cystinuric phenotype. There was mental retardation notwithstanding the normal ophthalmologic examination. Intravenous pyelography showed calyceal clubbing, calyceal cysts, and lobulated renal outlines of the fetal type. The patient was evaluated again at the age of 13 years for deterioration of visual acuity and the ophthalmologic examination showed an atypical retinal dystrophy, with sparse pigmentation, central and peripheral atrophy, attenuated vessels, and marked optic disk pallor. To our knowledge the association of Bardet-Biedl syndrome with cystinuria has never been reported. It is unlikely that cystinuria may have contributed to the kidney damage. The possibility that mental retardation has been induced or aggravated by cystinuria cannot be excluded.

Adult↗
PubMed1991

Hepatic computed tomography for monitoring the iron status of haemodialysis patients with haemosiderosis treated with recombinant human erythropoietin.

1. A randomized, partial-crossover study was conducted in uraemic patients with dialysis-associated anaemia and transfusional iron overload to evaluate the effects of desferrioxamine chelation therapy and of recombinant human erythropoietin treatment on hepatic iron storage determined by computed tomography, as well as by serum ferritin concentration and transferrin saturation. 2. Twenty-one haemodialysis patients with moderate iron overload, confirmed by values of serum ferritin concentration, transferrin saturation and hepatic computed tomography density exceeding 1000 micrograms/l, 45% and 68 Hounsfield units respectively, were randomly allocated to three groups and were followed for 12 months. 3. During the first 6 months group 1 (n = 7) received desferrioxamine chelation therapy (30 mg/kg intravenously three times a week) and group 2 (n = 7) underwent recombinant human erythropoietin treatment (36 units/kg intravenously three times a week). Thereafter, in the second 6 months of observation patients in group 1 were switched to receive recombinant human erythropoietin. Because of a poor response in the desferrioxamine-treated group in the initial 6 months, patients in group 2 continued on the maintenance dose of recombinant human erythropoietin (18 units/kg three times a week) until the end of the trial. Patients in group 3 (n = 7) were maintained on placebo throughout the study. 4. In comparison with placebo, recombinant human erythropoietin treatment, but not desferrioxamine chelation therapy, reduced serum ferritin concentration, transferrin saturation and hepatic computed tomography density, and was associated with a rise in haemoglobin and packed cell volume. Hepatic computed tomography density, serum ferritin concentration and transferrin saturation decreased in 13 out of 14 patients (93%) during treatment with recombinant human erythropoietin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Asymptomatic autoimmune thyroiditis and thyroid dysfunction in Alport's syndrome. A report of three families.

The purpose of this study was to investigate the significance of serum antithyroid antibodies in Alport's syndrome. Thyroid microsomal and thyroglobulin antibodies were assessed in three families with Alport's syndrome for a total of 11 patients and 17 healthy relatives, as well as in 40 haemodialysis patients and in 40 healthy subjects. Thyroid function tests, including the measurement of serum total thyroxine (TT4), total triiodothyronine (TT3), free thyroxine (fT4) and free triiodothyronine (fT3) concentrations, and thyrotropin-releasing hormone (TRH) stimulation tests were performed in all patients and subjects. Among patients with Alport's syndrome, five (45%) had elevated titres of thyroid microsomal antibodies and eight (73%) had positive titres of thyroglobulin antibodies, whereas only one healthy relative (6%) had circulating antithyroid antibodies. Fine-needle aspiration biopsy of the thyroid demonstrated a lymphocytic infiltration that indicated the existence of asymptomatic autoimmune thyroiditis in all five patients with elevated thyroid microsomal antibody titres. The prevalence of antithyroid antibodies in healthy subjects and in haemodialysis patients was 7.5% and 12.5% respectively. Functional tests demonstrated a thyroid dysfunction in four of five patients with asymptomatic autoimmune thyroiditis. Two patients had evidence of subclinical hypothyroidism. Two other patients, both with end-stage renal failure, showed a blunted TSH response to TRH, increased fT4 and elevated borderline fT3. The present study indicates that elevated titres of serum antithyroid antibodies may be detected in patients with Alport's syndrome. These patients are at risk of developing asymptomatic autoimmune thyroiditis and thyroid dysfunction. Subclinical hypothyroidism and, perhaps, preclinical hyperthyroidism may be found in these patients.

Adult↗
PubMed1990

Efficacy of hepatic computed tomography to detect iron overload in chronic hemodialysis.

The diagnostic efficacy of hepatic computed tomography density (HCTD) in comparison with serum ferritin for the detection of iron overload was investigated in uremic patients on maintenance hemodialysis (HD) and in patients with idiopathic hemochromatosis (IHC). Ten IHC patients, 38 HD patients and 40 healthy subjects underwent the CT scanning of the liver and determination of percent saturation of transferrin, serum ferritin concentration and HLA typing. Liver iron content was determined by histochemical grading and direct measurement of liver iron concentration either in IHC patients or in HD patients. Nineteen HD patients were considered to have iron overload on the basis of liver iron concentration exceeding 3.6 mumol/100 mg dry weight. The mean +/- SD values of HCTD in healthy subjects, IHC patients, HD patients with iron overload and without iron overload were 60.2 +/- 5.6, 79 +/- 5.6, 71.4 +/- 3.6, 58 +/- 3.8 Hounsfield units, respectively. HCTD showed positive correlations with liver iron concentration and serum ferritin either in IHC patients or in HD patients. The analysis of the diagnostic efficacy of HCTD in comparison with serum ferritin for the detection of excessive hepatic iron in HD patients demonstrated that HCTD had higher sensitivity, specificity, positive and negative predictive values. Cut-off points were arbitrarily fixed to 66 Hounsfield units for HCTD, 400 micrograms/liter for serum ferritin and 3.6 mumol/100 mg dry weight for liver iron concentration. Seventeen HD patients who possessed the histocompatibility antigens associated with IHC, namely HLA-A3 and/or HLA-B7 and/or HLA-B14, had liver iron concentration, serum ferritin and HCTD values higher than those of the HD patients without these "hemochromatosis alleles".(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗