Alterations in skeletal muscle ion and amino acid transport in chronic renal failure.
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Amino Acids↗
Biomedical subjects
A Novarini
Publications and source records attributed to A Novarini.
Renin-angiotensin system unresponsiveness in phaeochromocytoma.
Water immersion to the neck is able to provoke a profound suppression of the renin-angiotensin system in several clinical conditions associated with hyper-reninaemia. Both hyper-reninaemia and secondary aldosteronism have sometimes been described in phaeochromocytoma. We report on two patients, with surgically proven phaeochromocytoma, in whom water immersion, performed before surgery, failed to induce any significant change in plasma renin activity.
Adrenal Gland Neoplasms↗
Vertebral mineral content in diet-dependent and diet-independent hypercalciuria.
The vertebral mineral content was measured using dual photon absorptiometry in 41 calcium stone patients with idiopathic hypercalciuria. These patients had been previously divided into 2 groups (diet-dependent and diet-independent hypercalciuria) during a low sodium and low calcium diet. In some of the patients (11 with diet-dependent and 11 with diet-independent hypercalciuria) the vertebral mineral content was evaluated in relation to serum ionized calcium, intact parathyroid hormone, alkaline phosphatase and osteocalcin determined after a low sodium and low calcium diet. The vertebral mineral content, expressed as Z-VMD, was normal in diet-dependent and lower in diet-independent hypercalciuric stone patients (-0.30 +/- 1.19 versus -0.26 +/- 1.18, p less than 0.02). In 7 of 21 patients (33.3%) the vertebral mineral content was less than 2 standard deviations of the normal value, indicating a true involvement in bone metabolism. Serum intact parathyroid hormone and osteocalcin levels were not different from the controls in both groups, while alkaline phosphatase activity and ionized calcium were higher in diet-independent hypercalciuric patients. Serum ionized calcium was negatively correlated with bone vertebral density. The results suggest that an increased bone turnover may be a primary event in causing hypercalciuria in calcium stone patients unable to decrease urinary calcium to less than the calcium intake.
Absorptiometry, Photon↗
A new diagnostic test for primary aldosteronism.
Isotonic-isooncotic central volume expansion by head-out water immersion was induced in six aldosterone-producing adenoma subjects and in six patients with idiopathic hyperaldosteronism. Plasma renin activity and plasma aldosterone levels did not significantly change during water immersion while serum cortisol was significantly suppressed (P less than .001) and the aldosterone-cortisol ratio increased (P less than .02) in aldosterone-producing adenoma patients. Water immersion also revealed the failure of plasma aldosterone levels to decrease below 10 ng/dL in these subjects, thus confirming previous results obtained during isotonic saline infusion. Otherwise, plasma renin activity and plasma aldosterone were significantly reduced (P less than .05 and P less than .01 respectively) by water immersion and plasma aldosterone invariably fell below 10 ng/dL in patients with idiopathic aldosteronism. In view of the diagnostic reliability of such a suppression test we conclude that water immersion is suitable for discriminating between the two forms of primary aldosteronism. We therefore suggest its use for assessing renin-aldosterone responsiveness in primary aldosteronism.
Adenoma↗
Role of blood pressure in the natriuretic response to acute calcium channel blockade in humans.
Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and renal excretion of sodium and lithium were measured before and after acute oral administration of 20 mg nifedipine in 19 essential hypertensive patients. In 10 of them, with a diastolic pressure less than 105 mm Hg, nifedipine resulted in a decrease in mean blood pressure toward normal (109 +/- 2 to 97 +/- 2, p less than 0.001), a 27% increase in ERPF (p less than 0.001), no change in GFR, and an increase in fractional sodium excretion (28%, p less than 0.001). In nine subjects with a diastolic pressure greater than or equal to 105 mm Hg, nifedipine produced a decrease in mean blood pressure (133 +/- 6 to 117 +/- 4, p less than 0.001), which however remained higher than in mild hypertensives (p less than 0.001). ERPF rose by 29% (p less than 0.001), GFR remained unchanged, and fractional sodium excretion definitely increased more than in mild hypertensives (126%, p less than 0.001), as did fractional lithium excretion, used as an estimate of proximal tubular sodium handling. Acute nifedipine produces renal vasodilation in hypertensives, but with a greater natriuretic response in those subjects whose blood pressure remains elevated. Thus, acute natriuresis following nifedipine administration is largely dependent on the interaction between changes in arterial pressure and renal hemodynamics.
Blood Pressure↗
Sodium metabolism in human essential hypertension.
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Biochemical Phenomena↗
[Antihypertensive treatment: a combination of delapril, a new ACE-inhibitor, and indapamide].
The controlled study was carried out on 15 patients with essential hypertension not sufficiently controlled after one month of monotherapy with an ACE-inhibitor. To the above therapy was therefore associated a low dosage diuretic (indapamide 2.5 mg/day). The observation period was of 12 weeks. The delapril-indapamide combination was found to be very effective in reducing blood pressure values; no significant metabolic adverse effects were observed.
Adult↗
Dopaminergic modulation of acute renal effects of nicardipine.
In order to investigate whether dopamine receptors are involved in the acute natriuretic effects of calcium channel blockade, experiments were carried out in humans with uncomplicated essential hypertension. In 8 hypertensives 5 mg intravenous nicardipine produced a large decrease in blood pressure and renal vascular resistance, a slight but significant increase in glomerular filtration rate (GFR) and marked natriuresis. When a second identical experiment was performed in the same subjects with the addition of 10 mg metoclopramide as dopamine blocker, changes in sodium excretion and vascular resistance were the same, but GFR did not increase during nicardipine. In a second set of experiments (n = 5) the same design was used, but nicardipine was infused at a dose of 0.01 mg/kg, ie, seven times less than in previous experiments. Under these conditions, blood pressure, renal vascular resistance and GFR did not change, but significant natriuresis occurred. Natriuresis was almost completely prevented by metoclopramide. In 5 additional hypertensives, metoclopramide alone was infused and 0.01 mg/kg nicardipine was added to the infusion. No change in any parameter was observed. Our findings suggest that the dopaminergic system participates in maintaining or increasing GFR during blood pressure reduction by calcium antagonists, although renal vasodilation and natriuresis are largely independent of dopamine receptor activity. In addition, when low doses of calcium antagonists produce natriuresis in the absence of renal or systemic hemodynamic changes (direct tubular effect), dopamine blockade is able to blunt this effect. This indicates a modulation by dopaminergic receptors of the direct tubular action of calcium antagonists.
Blood Pressure↗
Sodium homeostasis and hormonal responses during dopaminergic blockade in normal humans.
Six normal subjects were submitted to 2 h water immersion (WI) with and without pharmacological dopaminergic (DA) blockade with metoclopramide (MCP). Urinary sodium excretion showed a marked increase during WI alone while it was blunted during WI plus DA blockade. Plasma aldosterone was significantly suppressed by WI alone but remained unchanged during WI plus MCP. Plasma atrial natriuretic factor showed similar augmentation during WI alone and during WI plus MCP. The reduced sodium and 6-keto-PGF1 alpha excretion, observed during WI plus MCP administration, suggests that dopamine might induce prostacyclin synthesis in the kidney during WI.
Adult↗
Epidemiological study of urinary tract stones in a northern Italian city.
An epidemiological study of stone disease in a Northern Italian city was carried out by means of a postal questionnaire mailed to 6000 individuals (2.5% of the entire population). It was found that the incidence of stone disease was comparable to that of industrialised Western Europe. There was a relationship between stone disease and gout and stone disease and a positive family history. The frequency of uric acid stones was high (26.5%). Stone-formers showed no alimentary differences from non-stone formers apart from the use of spices and herbs. Stone-formers used less water from public aqueducts and more uncarbonated mineral water, but only 19% of these drank at least 2 litres a day.
Adult↗
[Cystinuria: description of a simple method of determination and our 5-year clinical experience].
Ion exchange chromatography is the best method for the determination of cysteine in urine, but it requires an expensive apparatus, specialized technicians and a long time. The major colorimetric procedure is the nitroprusside color reaction first described by Brand, but it involves the reaction with toxic cyanide reagent. Moreover commercial stick are not available. We have experienced a colorimetric procedure in which the sulfhydryl group of cystine reduces phosphotungstic acid to tungstic blue, which is determined photometrically. This procedure avoids the use of cyanide. We used this screening test during 5 years of ambulatory evaluation of nephrolithiasis and we found these results: urine cystine 191 controls: 87 +/- 57 mg/day, 870 stone oxalate and uric acid patients: 99 +/- 57 mg/day, 11 stone cystine patients: 479 +/- 379 mg/day (p 0.001). A close correlation was found in stone cystine patients between our data obtained in the same sample with ion exchange chromatography. We conclude that this inexpensive and simple method can be recommended as a screening test for cystinuria.
Adolescent↗
Increased urinary 6-keto-PGF1 alpha excretion during water immersion is blunted by metoclopramide in normal man.
Urinary excretion of 6-keto-PGF1 alpha and 2,3 dinor-6-keto-PGF1 alpha, as indices of the renal and systemic production of prostaglandins, was measured during water immersion in a group of 6 healthy volunteers both in the presence and absence of dopamine blockade by the dopamine receptor antagonist, metoclopramide. Urinary flow rate and excretion of both sodium and 6-keto-PGF1 alpha increased during water immersion, while plasma renin activity and plasma aldosterone were reduced. Urinary kallikrein and 2,3 dinor-6-keto-PGF1 alpha also tended to increase during water immersion. Administration of metoclopramide significantly reduced 6-keto-PGF1 alpha and sodium excretion during water immersion, but produced no changes in plasma renin activity or in 2,3 dinor-6-keto-PGF1 alpha. Plasma aldosterone concentrations after metoclopramide were similar to those observed in the pre-immersion period. An increased synthesis of the vasodilator and natriuretic prostacyclin in the kidney might play a role in the response to water immersion. The reduced sodium and 6-keto-PGF1 alpha excretion observed after metoclopramide administration suggests that dopamine might induce prostacyclin synthesis in the kidney during water immersion.
6-Ketoprostaglandin F1 alpha↗
The antinatriuretic effect of dopaminergic blockade during volume expansion is independent of circulating atrial natriuretic factor.
1. Ten normal subjects were subjected to 2 h water immersion with and without pharmacological dopaminergic blockade with either metoclopramide (group I) or domperidone (group II). 2. In group I, urinary sodium excretion showed a marked increase during water immersion alone, whereas it was blunted during water immersion plus dopaminergic blockade with metoclopramide (P less than 0.05 vs water immersion alone, n = 5). Plasma aldosterone was significantly suppressed by water immersion alone (P less than 0.05), but remained unchanged during water immersion plus metoclopramide. Plasma atrial natriuretic factor showed similar augmentation during water immersion alone and during water immersion plus metoclopramide. 3. Another five subjects (group II) were studied during water immersion alone and during water immersion plus dopaminergic blockade with domperidone. In this group the increase in urinary sodium excretion was similarly blunted by dopaminergic blockade. Plasma atrial natriuretic factor was equally elevated during water immersion alone and during water immersion plus domperidone, but aldosterone was suppressed by both water immersion alone and water immersion plus domperidone. 4. Our findings suggest that water immersion-induced atrial natriuretic factor release is independent of dopaminergic activity. Dopamine blockade is able to blunt significantly both water immersion-induced natriuresis and plasma aldosterone suppression, independently of the marked elevation of circulating atrial natriuretic factor, via a mechanism involving type 2 dopaminergic receptors.
Adult↗
[Curriculum of graduate studies in medicine and surgery: study on graduates in Parma from 1983-1984 to 1987-1988].
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Curriculum↗
The influence of ubiquinone (Co Q10) on the metabolic response to work.
Ubiquinone (Co Q10) is a natural substance suitable for therapeutic use in cardiology and in the treatment of some muscular diseases. It might therefore be used during strenuous exercise (as in athletic competitions), especially in the presence of metabolic modifications which may justify its use. For this purpose, we have evaluated the effect of prolonged treatment with Co Q10 (100 mg/day per os for one month) on the biological changes induced by prolonged work on an ergometer bicycle (equal to about 50% of the single VO2max per 60 m'), immediately followed by exhaustive work (25 watts increase every 2 m'). From the venous blood of 12 healthy untrained subjects (students, volunteers, mean age 25.7 and body mass index 23.3) we examined some biological parameters [free fatty acids (FFA), free glycerol, lactate, glucose, insulin, CK] before, at the end of aerobic work, at the end of exhaustive work, and after 30 and 60 m' of the recovery phase. The same indexes, measured after identical times and work, were evaluated after one month of treatment with Co Q10. The only relevant modifications observed were those concerning FFA: at the end of aerobic work and after the administration of the drug, lower levels were reached (before, 1011 +/- 329 microEq/l; after 790 +/- 392; p less than 0.05); the same trend was observed at the end of the exhaustive work (1031 +/- 320 microEq/l vs 826 +/- 387; p less than 0.05). At the subsequent times, as well as for the other biological parameters examined, we did not observe any variation before or after the period of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Role of renal hemodynamics in the exaggerated natriuresis of essential hypertension.
Extracellular fluid volume expansion is known to produce exaggerated natriuresis in essential hypertension. In order to assess the role of hemodynamic and intrarenal physical factors upon natriuretic response to central volume expansion, two hour water immersion (WI) experiments were made in six uncomplicated essential hypertensives and six normotensive healthy controls. Before and during WI we measured mean arterial pressure (MAP), urine flow (V/min), sodium (UNaV) and potassium (UKV) excretion, glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and intrarenal (wedged) venous pressure (IRVP). In comparison with normotensive controls, the exaggerated natriuretic response in hypertensives (P less than 0.05 for UNaV during WI) was associated with an enhanced vasodilating response as demonstrated by a greater increase in ERPF (P less than 0.05) and by a more pronounced fall in calculated renal precapillary resistances (P less than 0.05). A more significant increase in IRVP was found in hypertensive group (P less than 0.05). Glomerular filtration rate (GFR) did not change in either group during WI. MAP, unchanged in normotensives, was significantly reduced in hypertensives (P less than 0.05), while remaining in the hypertensive range. These findings suggest that intrarenal physical factors play a major role in determining the exaggerated natriuresis during WI in hypertensive man.
Adult↗
Circulating opioid peptides during water immersion in normal man.
1. This study was designed to evaluate variations in plasma beta-endorphin, methionine-enkephalin, adrenocorticotropic hormone and serum prolactin in healthy volunteers during head-out water immersion. 2. Water immersion induced an increase in methionine-enkephalin plasma levels, which was associated with a significant fall in mean arterial pressure and heart rate. 3. Conversely, a suppression of plasma beta-endorphin, adrenocorticotropic hormone and serum prolactin was detected during water immersion. 4. We suggest that a dopaminergic inhibitory control mechanism may be involved in regulating circulating levels of beta-endorphin, adrenocorticotropic hormone and prolactin in normal subjects undergoing extracellular fluid volume expansion produced by water immersion.
Adrenocorticotropic Hormone↗
Acute effect of indapamide on urine calcium excretion in nephrolithiasis and human essential hypertension.
The effects of indapamide (2.5 mg once a day) on urinary composition are reported in 20 patients (10 with recurrent calcium nephrolithiasis and 10 with essential hypertension) compared with 20 controls. Indapamide was well absorbed in every patient (mean plasma level at the steady state was 111 +/- 41 ng/ml) and its antihypertensive action was more pronounced in hypertensive than in normotensive patients. It lowered calcium excretion in 18/20 patients (mean fall on the 7th day of treatment: 53%) and raised the Mg/Ca ratio in 20/20 patients (mean increase on the 7th day: 167%). The effect on Ca2+ and Mg2+ excretion was not associated with a strong diuretic effect. During intravenous calcium loading (0.375 mmol/kg body weight) 6 normal subjects after a single oral dose of indapamide excreted less calcium, suggesting a direct renal hypocalciuric action by the drug. Indapamide could represent an alternative drug to thiazide diuretics in diseases with dangerous renal calcium losses, but long-term studies are needed.
Adult↗