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Biomedical subjects

C Zoccali

Publications and source records attributed to C Zoccali.

At least 19 recordsLinked to original sources
PubMed1992

The influence of autonomic failure on plasma ANF concentration in uremic patients on chronic hemodialysis.

We compared plasma ANF concentration in 5 diabetic-uremics with combined sympathetic-parasympathetic dysfunction with that in 9 uremic patients without autonomic impairment. Symptomatic dialysis hypotension was a major clinical problem in all diabetic-uremics. In the volume-expanded state, ANF was almost twice as high (p less than 0.025) in diabetic-uremics than in control uremics (152 +/- 29 vs 84 +/- 10 pg/ml) in the face of similar right atrial pressure (14 +/- 3 vs 12 +/- 1 cm H2O). After isolated ultrafiltration, ANF fell significantly in both groups remaining slightly (NS) higher in diabetic-uremics. The slope of the relationship between ANF and right atrial pressure was significantly (p less than 0.01) steeper in diabetic-uremics than in control uremics. The data indicate that autonomic failure amplifies the effect of atrial stretching on plasma ANF in diabetic-uremics on chronic hemodialysis treatment.

Adult↗
PubMed1991

Hyperfiltration and calcium metabolism in essential hypertension.

To test the hypothesis that hyperfiltration in essential hypertension is linked to alterations in calcium metabolism, we studied the relationship between urinary calcium excretion and glomerular filtration rate (GFR, creatinine clearance) in 38 untreated essential hypertensives on a free diet. We also studied the influence of changes in calcium intake on GFR in 30 essential hypertensives (15 with well-defined hypercalciuria and 15 with normal urinary calcium excretion) and in 11 normotensive healthy subjects. In the patients on a free diet, urinary calcium excretion was directly and independently related to GFR (r = 0.56, P less than .001), while serum calcium showed an opposite trend (r = -0.27, P = .12). In patients on fixed calcium diets, GFR was significantly higher (P = .008) at low calcium intake (115 +/- 31 mL/min/1.73 m2) than at high calcium intake (98 +/- 22 mL/min/1.73 m2). Further analysis showed that the hyperfiltering effect of low calcium almost exclusively occurred in hypercalciuric patients and in hypertensive women. In hypercalciuric hypertensives there was a highly significant inverse correlation between GFR and serum calcium (r = -0.51, P = .004) and a similar correlation between GFR and plasma renin activity (r = -0.70, P = .003) in the high calcium phase of the study. Changes in calcium intake had no influence on GFR in normal subjects (Low Ca 103 +/- 22 mL/min/1.73 M2, High Ca 110 +/- 23 mL/min/1.73 m2). The data indicate that alterations in calcium metabolism interfere to an important extent with mechanism(s) regulating GFR in essential hypertension.

Adult↗
PubMed1991

The reflex control of vasopressin in haemodialysis patients.

We studied the reflex arginine vasopressin (AVP) response to hypotensive, isosmotic fluid subtraction (by isolated UF) in 14 uraemic patients on renal dialysis treatment: five with normal autonomic function and nine with autonomic involvement of various degrees. Fluid subtraction caused a comparable mean arterial pressure (MAP) decrease in the two groups. The reduction in right atrial pressure was inversely related with the severity of autonomic neuropathy (rs = -0.72, P = 0.004), being distinctly attenuated in the second group (P = 0.006). Plasma arginine vasopressin increased similarly in patients with normal autonomic function and in those with autonomic involvement. The response of patients with haemodialysis hypotension was similar to that of other patients. Reflex control of arginine vasopressin is preserved even in the presence of afferent/central neuropathy or more advanced, widespread autonomic damage in uraemic man. The data suggest that it is unlikely that altered release of arginine vasopressin is involved in the pathogenesis of haemodialysis hypotension.

Adult↗
PubMed1991

Mechanism of hypercalciuria in essential hypertension and in primary nephrolithiasis.

We have studied the metabolic response to changes in calcium in 15 hypercalciuric essential hypertensives, in 8 normotensive hypercalciuric stone formers and in 11 normotensive healthy subjects matched for age and sex. At variance with hypercalciuric stone formers, at low calcium intake hypercalciuric hypertensives did not appropriately reduce urinary calcium excretion and developed mild hypocalcemia. Furthermore, the PTH response to calcium deprivation was not appropriately enhanced in these patients. The data indicate that different mechanisms prevail in these two forms of hypercalciuria: the renal in essential hypertension and the intestinal in urolithiasis.

Adult↗
PubMed1989

The 'breakpoint' test, a new statistical method for studying progression of chronic renal failure.

The application of a new statistical method ('breakpoint' test) to the study of the progression of chronic renal failure is described. This test establishes whether the best fit of a series of GFR measurements is linear or broken. Such an approach avoids the analytical constraint of the time of intervention assumed by other methods. Re-analysis by this test of previous studies of low-protein diet suggests that in some cases the effect of the dietary regimen has been overemphasized.

Creatinine↗
PubMed1989

Postprandial alterations in arterial pressure control during hemodialysis in uremic patients.

To test the hypothesis that eating may adversely affect the hemodynamic response to ultrafiltration-dialysis, we studied the effect of a standard snack (about 400 Kcal) in 13 patients on RDT. Each patient was studied in random order during two standard hemodialysis sessions (snack-HD and control-HD) performed at identical UF rate. Arterial pressure fell significantly (p less than 0.01) during both the Control-HD (from 135 +/- 8/76 +/- 3 to 121 +/- 10/68 +/- 5 mmHg) and the Snack-HD (from 137 +/- 7/77 +/- 3 to 105 +/- 8/59 +/- 4 mmHg). The rate of fall, however, was significantly higher (p less than 0.01) after the snack than during the corresponding period in the control HD. Consequently, there were more hypotensive episodes requiring saline infusion during Snack-HD (23 in 10 patients) than during Control-HD (12 in 6 patients) (p less than 0.025). In spite of the greater number of interventions, the average fall in arterial pressure after a snack (-22 +/- 3/-13 +/- 2 mmHg) was more marked than during the corresponding period in the control-HD (-13 +/- 3/-9 +/- 2 mmHg). The hypotensive effect of snack was more pronounced in the presence of advanced autonomic neuropathy. Food ingestion impairs the arterial pressure response to UF in patients on RDT. Fasting during hemodialysis may in part prevent hypotension.

Autonomic Nervous System↗
PubMed1988

Double-blind randomized, crossover trial of calcium supplementation in essential hypertension.

In a double-blind, randomized, placebo-controlled, crossover trial, 23 middle-aged patients with mild to moderate essential hypertension were given an oral calcium supplement (1 g/day) for 8 weeks. At the end of this period, eight patients continued with this treatment for an additional 2 weeks but were also given 0.5 micrograms/day of 1,25-(OH)2 vitamin D3. In the 21 patients who completed the study, arterial pressure during the calcium-supplemented phase was almost identical to that of the placebo phase. In eight patients, mean arterial pressure (MAP) had changed by greater than 5 mmHg at the end of the calcium-supplemented period, compared with the end of the placebo phase (six patients showed an increase in MAP and two a decrease). Changes in arterial pressure were unrelated to age, plasma ionized calcium, parathyroid hormone (PTH), plasma renin activity (PRA), plasma aldosterone, 24-h urinary calcium, sodium and potassium and were only weakly related to body weight. In the eight patients who continued with the treatment of calcium plus 1,25-(OH)2 vitamin D3 after the 8-week study period, arterial pressure changed very little and not significantly. These results do not support the suggestion that calcium supplements lower arterial pressure in middle-aged subjects with mild to moderate essential hypertension.

Adult↗
PubMed1987

Severe hypothyroidism induced by amiodarone in a dialysis patient.

A 54-year-old man on regular haemodialysis developed severe amiodarone-induced hypothyroidism after an unusually short latency period. The iodide accumulation and/or the derangement in thyroid function associated with chronic renal failure may predispose uraemic patients to this serious side effect of amiodarone. Although the pharmacokinetics of amiodarone are not altered by renal failure, caution is advised in prescribing this drug to uraemic patients.

Amiodarone↗
PubMed1987

Plasma met-enkephalin and leu-enkephalin in chronic renal failure.

Plasma met-enkephalin and leu-enkephalin has been measured in a group of 28 patients with chronic renal failure, to discover whether these opioids are affected by standard haemodialysis and haemofiltration. Met-enkephalin was markedly higher (P less than 0.001) in uraemic patients than in a group of 13 normal subjects, and was directly related to plasma creatinine (r = 0.60; P less than 0.01) and to plasma urea (r = 0.36; P = 0.06). In contrast, leu-enkephalin was suppressed in uraemic patients (P less than 0.001). Met-enkephalin fell slightly but significantly (P less than 0.02) after both haemodialysis and haemofiltration; however, on average it remained at concentrations four times higher than normal. No changes in plasma leu-enkephalin were observed after haemodialysis and haemofiltration. The cause(s) of the altered plasma concentrations of these opioid substances remains to be clarified.

Adult↗
PubMed1986

Parasympathetic function in haemodialysis patients.

The long-term course of the parasympathetic neuropathy in patients with chronic renal failure maintained on haemodialysis was investigated. Well-established tests of parasympathetic function (deep breathing test, atropine test) were performed in 45 patients who had been dialysed for periods ranging from 1 to 12 years and in 34 normal subjects. The responses to these tests were clearly compromised in dialysis patients but there was no relationship between duration of haemodialysis treatment and results of parasympathetic tests. In the 13 patients who were re-evaluated after an interval of 4 years there was no evidence of progression of the parasympathetic neuropathy. The results suggest that chronic haemodialysis treatment halts parasympathetic damage in patients with chronic renal failure.

Adult↗
PubMed1986

Effect of ultrafiltration on plasma concentrations of atrial natriuretic peptide in haemodialysis patients.

We have investigated the influence of body fluid volume status on plasma levels of immunoreactive atrial natriuretic peptide (irANP) in eight uraemic patients on chronic haemodialysis, including two diabetics with severely impaired reflex control of the heart. IrANP was significantly higher in volume-expanded uraemic patients (36 +/- 16 pg/ml) than in a group of seven age and sex-matched normal subjects (14 +/- 2 pg/ml), and fell consistently, approaching the normal range after the removal of 2.0-4.3 litres of isotonic plasma ultrafiltrate (by isolated ultrafiltration). Plasma levels of the hormone were strictly related to right atrial pressure. The irANP response to ultrafiltration in the two diabetics was similar to that of the other uraemic patients. The results suggest that the elevated irANP levels found in volume-expanded uraemic patients depend largely on fluid overload per se. The preserved irANP response to ultrafiltration of the two diabetics with severe autonomic neuropathy indicates that in chronic renal failure irANP secretion may be regulated independently from autonomic influences.

Adult↗
PubMed1986

Autonomic function in uremic patients treated by hemodialysis or CAPD and in transplant patients.

Tests of autonomic nerve function have been performed in patients receiving dialysis and following transplantation. These tests, consisting of blood pressure and heart rate response to standard stimuli were carried out in four groups of subjects: 10 patients were receiving continuous ambulatory peritoneal dialysis (CAPD), 12 hemodialysis, 11 had functioning transplants and there were 12 healthy subjects. The heart rate responses to the Valsalva maneuver, deep breathing and standing were equally reduced in the hemodialysis and CAPD patients while the responses in the transplant patients were not significantly different from those in the control subjects. Peroneal nerve conduction velocity was used to measure the degree of peripheral neuropathy and while in most patients there was a positive relationship with the autonomic studies, in five patients the results were clearly dissociated. Plasma parathyroid hormone (PTH) levels were elevated in both the dialysis groups but not in the transplanted patients and there was no correlation between the PTH levels and any of the neurological tests. This study has confirmed the presence of autonomic neuropathy in dialysed uremic patients and has demonstrated almost complete resolution of this following transplantation but has failed to show any benefit of CAPD over hemodialysis in protecting against neuropathy.

Adult↗
PubMed1985

Effect of naloxone on the defective autonomic control of heart rate in uraemic patients.

The role of endogenous opioids on the reflex cardiovascular control of chronic uraemic patients was investigated. The opiate antagonist naloxone administered intravenously caused a significant increase in the abnormal Valsalva manoeuvre ratio in nine chronic uraemic patients, but it had no effect in six diabetic patients with normal renal function, whose response to the Valsalva manoeuvre was similar to that of chronic uraemic patients. Naloxone had no effect in eight normal subjects. The increase in the Valsalva ratio observed in uraemic patients was due to restoration of the parasympathetically mediated reflex bradycardia of the release phase of the manoeuvre. Naloxone did not modify supine and standing blood pressure and heart rate in any group. Endogenous opioids may be involved in the defective autonomic control of heart rate in uraemic patients.

Adult↗