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Biomedical subjects

F Malberti

Publications and source records attributed to F Malberti.

At least 55 records · Page 3Linked to original sources
PubMed1987

Pharmacological evaluation of urate renal handling in humans: pyrazinamide test vs combined pyrazinamide and probenecid administration.

Uricosuric and antiuricosuric drugs have been utilised widely for the study of tubular urate transport in humans. A normal suppression of urate excretion after pyrazinamide is usually taken as evidence of normal presecretory reabsorption. However, in patients with reduced presecretory reabsorption, during pyrazinamide inhibition of urate secretion unreabsorbed urate might still undergo reabsorption along postsecretory sites, allowing for a normal pyrazinamide suppression of urate excretion. To test this possibility, we have performed the pyrazinamide test both alone and after pretreatment with probenecid, which should block postsecretory urate reabsorption. The test was performed in 8 controls, in 9 patients with 'low-excretory' hyperuricaemia, and in 7 patients with tubular urate wasting. Pyrazinamide-non-suppressible urate excretion after pretreatment with probenecid did not differ from the excretion obtained after pyrazinamide alone in hyperuricaemic patients (mean difference 1.33 +/- 2.3% of filtered urate; P = NS); it was slightly higher in controls (3.4 +/- 3.4; P less than 0.05), but was much higher in patients with tubular urate wasting (19.6 +/- 12.7; P less than 0.005). The pyrazinamide test, performed alone, was normal in three patients with tubular urate wasting, but it was abnormal in all patients after pretreatment with probenecid. These results are consistent with the possibility that, during maximal pyrazinamide effect, some uric acid escaping reabsorption at presecretory sites may undergo reabsorption along postsecretory sites, leading to a quantitative overestimation of presecretory reabsorption. This phenomenon appears to have clinical relevance, especially in patients with abnormal urate reabsorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

The influence of dialysis fluid composition on dialysis tolerance.

To evaluate the role of bicarbonate loss through the dialyser and acetate flux to the patient in the development of symptoms during acetate dialysis, bicarbonate loss during acetate dialysis was prevented by using a combination of acetate and bicarbonate in the dialysate. Seven uraemic patients were treated for 4 months with acetate dialysis and, successively, for a similar period of time with bicarbonate, and a combination of acetate and bicarbonate dialysis. Blood-pressure drop and the incidence of hypotension and symptomatic episodes were similar in bicarbonate and combination dialysis, and significantly lower than in acetate dialysis. Serum acetate concentrations were similar during acetate and combination dialysis. These findings indicate that bicarbonate loss rather than the presence of acetate was responsible for the patients' intolerance to acetate dialysis.

Acetates↗
PubMed1987

Clinical evaluation of segmental tubular reabsorption of sodium and fluid in man: lithium vs free water clearances.

Segmental sodium reabsorption in the proximal and distal tubule was evaluated by different methods in seven healthy subjects, seven patients with recurrent calcium nephrolithiasis, five patients with isolated renal glucosuria and three patients with Fanconi syndrome. In all the subjects, the delivery of fluid from the proximal tubule, evaluated as 'chloride' factor during maximal water diuresis (DDCl, 12.4 +/- 5.5 ml/dl GFR), was lower (P less than 0.001) than 'volume' or 'chloride' factors during maximal water diuresis plus frusemide administration (40 mg i.v.) (Vf, 22.5 +/- 7.5 and DDClf, 27.1 +/- 8.9 ml/dl GFR, respectively), and of lithium clearance (FELi, 28.1 +/- 12.6%). Vf was lower than DDClf (P less than 0.001) and FELi (P less than 0.005), while DDClf and FELi did not differ; these unequal results are likely to represent different degrees of free water back-diffusion along distal tubule segments in the free water clearance studies. Accordingly, estimation of sodium reabsorption in the distal tubule showed corresponding differences within the four methods as those observed for the distal delivery: it was 25.5 +/- 12.2% when evaluated as [FELi-FECl]; 24.8 +/- 8.3 ml/dl GFR when evaluated as [CH2Of/GFR + delta FECl] (i.e. free water clearance during frusemide plus the frusemide-induced absolute increase in FECl); 19.5 +/- 6.7 ml/dl GFR (P less than 0.001 vs [FELi-FECl] and [CH2Of/GFR + delta FECl] when evaluated as [(CH2O + CH2OBD)/GFR] (i.e. CH2O before frusemide plus the frusemide-induced absolute increase in urine flow rate); and 10.0 +/- 4.8 ml/dl GFR when evaluated as CH2O (P less than 0.001 vs all the other evaluations).(ABSTRACT TRUNCATED AT 250 WORDS)

Furosemide↗
PubMed1985

Vitamin D metabolites and osteomalacia in the human Fanconi syndrome.

Experimental evidence suggests that renal 1 alpha-hydroxylase activity is impaired in Fanconi syndrome. We have evaluated plasma vitamin D metabolites in five patients with Fanconi syndrome, three of whom had metabolic bone disease; plasma 1,25(OH)2D3 was low in the three patients with bone disease, and normal in the two patients without a bone mineralisation defect. The data supports the hypothesis that renal 1 alpha-hydroxylase activity may be impaired in human Fanconi syndrome, and that altered vitamin D metabolism may contribute to the pathogenesis of metabolic bone disease in Fanconi syndrome.

Aged↗
PubMed1983

Relationship between sodium intake, proximal tubular function and calcium excretion in normal subjects and in idiopathic hypercalciuria.

Proximal tubular function was studied with maximal water clearance studies in 15 controls (C), 22 Ca stone formers with idiopathic hypercalciuria (IH) and 10 normocalciuric Ca stone formers (NC). Distal delivery of glomerular filtrate (ClDD) and Na excretion were higher in IH and NC than in C; NaCl loading (6 g/day) for seven days in C increased Na excretion and ClDD to similar levels as in IH and NC; the distribution of ClDD for any level of Na excretion was similar in C, NC and IH. NaCl loading in C slightly reduced renal phosphate threshold, which still remained higher than in IH on a free diet. It appears that reduced tubular reabsorption of glomerular filtrate in Ca stone formers is related to habitual high Na intake and is not peculiar to hypercalciuric patients. Habitual high Na intake is unlikely to be responsible for all the metabolic spectrum of idiopathic hypercalciuria.

Adolescent↗
PubMedDate not supplied

[Effect of an ambulatory program devoted to chronic renal insufficiency on the reduction of mobidity and hospitalization among patients at the beginning of dialysis treatment].

BACKGROUND: Late nephrological referral of end-stage renal disease (ESRD) patients is associated with increased risk of emergent dialysis start and poor complications control. However, the relative contribution of pre-dialysis care organization is unknown. METHODS: All 175 consecutive patients who started chronic dialysis for ESRD at our Institution from 1.1.99 to 30.6.02 were grouped as follows: referred ? 3 months before dialysis, (A, n=50); followed by non-dedicated specialists (B, n=74) or by pre-dialysis educational program personnel (PEP, n=51). We examined the first six months of hospitalization, uraemic complications control, type of dialysis initiation, and first dialysis modality. RESULTS: There was no difference in baseline characteristics and comorbidities among groups. PEP patients had higher creatinine clearance, haemoglobin, calcemia and BMI at initiation. They also made greater use of ACE-inhibitors and were more likely to have a planned start and choose peritoneal dialysis. Emergent starts were 50% (A 100%, B 45%, PEP 4%, p<0.001). Mean pre-dialysis hospitalization (due to in-patient emergency dialysis onset for unplanned starts and planned for access insertion for elective out-patient starts) was shorter among PEP patients (7days-PEP, 17days-B, 30days-A). Logistic regression confirmed the predictive role of PEP for emergent start (AOR 0.03, 0.001 to 0.101, p<0.001) even excluding late referrals (AOR 0.1, 0.033 to 0.306, p<0.001), independently of baseline characteristics and comorbidities. CONCLUSIONS: Pre-dialysis follow-up by dedicated personnel was more effective than traditional specialist care in reducing morbidity and health care resources utilization in patients starting dialysis.

Adult↗
PubMedDate not supplied

[Disturbances of mineral metabolism and vascular calcifications in dialysis patients (review)].

Vascular calcifications are more frequent in dialysis patients than in the general population or in patients with cardiovascular disease and normal renal function. The reasons for this high incidence are multiple. They include traditional factors such as hypertension, diabetes, dyslipidaemia, and specific factors such as sodium overload, hyperomocysteinaemia, chronic inflammation, oxidative stress as well as disturbance of mineral metabolism. Specifically, hyperphosphataemia and the elevated calcium (Ca) x phosphate product have been associated with an increased risk for development of vascular calcification and death. Even though a causal relationship between the use of Ca- containing phosphate binders and the development of vascular calcifications has not been documented, treatment with Ca salts can induce hypercalcaemia, increased Ca x phosphate product, and Ca overload. A net intestinal Ca absorption of 180-500 mg has been documented in uraemic patients after a meal containing 1200 mg of Ca. Thus, treatment with Ca salts may induce Ca overload when a patient is dialyszed against a high dialysate Ca (> 1.5 mmol/L) solution, which is known to determine a positive dialysis balance. On the contrary, an overall negative Ca balance can result from the use of a low Ca dialysate (1.25 mmol/L) when the patients do not receive Ca supplements or vitamin D metabolites. Maintaining a normal Ca and phosphate balance remains one of the primary goals in the management of dialysis patients. Control of hyperphopshataemia should be obtained using either Ca and aluminium- free phosphate binders, such as sevelamer, or Ca salts, while avoiding a daily oral elemental Ca intake > 1.5 g.

Calcinosis↗
PubMedDate not supplied

[Italian study on the treatment of anaemia in chronic dialysis patients switched over to less frequent doses of darbepoetin from human recombinant erythropoietin (rHuEPO)].

BACKGROUND: Darbepoetin alpha is a novel erythropoiesis stimulating protein with unique properties as compared to recombinant human erythropoietin (rHuEPO), including a three-fold longer elimination half-life that allows for less frequent dosing. This study was aimed at testing the efficacy and safety of darbepoetin alpha in a large number of chronic dialysis patients switched from rHuEPO. METHODS: Nine hundred and fifty dialysis patients in stable treatment with rHuEPO were switched to darbepoetin alpha. Patients receiving rHuEPO 2 or 3 times weekly were switched to once weekly darbepoetin alpha and those receiving rHuEPO once weekly were switched to once every other week darbepoetin alpha. Patients received darbepoetin alpha by the same route of administration (SC or IV) as the one used for rHuEPO. The unit doses of darbepoetin alpha (10-150 microg) were titrated to maintain haemoglobin concentration within -1.0 and +1.5 g/dL of the individual mean baseline haemoglobin levels and between 10 and 13 g/dL for 24 weeks. RESULTS: The mean change in haemoglobin from baseline to the evaluation period (weeks 21-24) was statistically but not clinically significant [-0.10 g/dL (95% CI: -0.18, -0.02]. In general, the geometric mean weekly dose of study drug from screening/baseline to evaluation period remained substantially unmodified [(from 26.10 micro g/wk to 25.90 microg/wk; percentage change -0.40% (95% CI: -3.78, 3.10)]. Overall, darbepoetin alpha was well tolerated. CONCLUSIONS: The treatment of anaemia of a large dialysis patient population with unit dosing of darbepoetin alpha is effective and safe in maintaining target haemoglobin concentration at reduced dose frequency.

Anemia↗
PubMedDate not supplied

[Epidemiology and demography of uremia: data from the Lombardy Dialysis and Transplantation Registry (RLDT)].

The Lombardy Registry of Dialysis and Transplantation (RLDT) since 1983 has collected data concerning patients affected by end-stage renal disease (ESRD) on renal replacement therapy (RRT) in Lombardy, a region of Northern Italy with 9 million inhabitants. This report illustrates the main features of ESRD patients on RRT: there were 6589 patients undergoing treatment at 31 December 2003, with a prevalence rate of 727 pmp. Patient numbers regularly increased by 4.5%/yr for the last 5 yrs. This phenomenon is probably due to the high incidence rate (172 pmp) of ESRD patients in Lombardy during these years related to a relatively stable mortality rate (15.2%). The increasing incidence is probably correlated to the population's characteristics: higher rates (189-223 pmp) were observed in certain provinces (Cremona, Lodi and Pavia) with a larger elderly population (people >65 yrs = >20%, people <65 yrs = <16%). Of dialysis modalities, 85% of prevalent patients were on hemodialysis (HD), 55% in hospital, and 30% in limited care units. The number of patients treated by peritoneal dialysis (PD) was stable during the last years, but showed a slow percentage decline (15% during 2003) since 1999. However, PD remains the first dialysis modality for 21.4% of new patients, with a wide variability among renal units. Regarding HD, highly efficient techniques (on-line hemodiafiltration (HDF)) represented 19.2%, with a significant increase (1.8%) compared to 2002. During 2003, the number of dialysis units in Lombardy was stable; there was only an increase in facility beds in limited care units in order to treat the increasing numbers of uremic patients.

Adult↗
PubMedDate not supplied

[Control of calcium and phosphate metabolism and prevention of vascular calcifications in uremic patients].

Vascular calcifications are more frequent in dialysis patients than in the general population or in patients with cardiovascular disease (CVD) and normal renal function. The reasons for this high incidence are multiple; they include traditional factors such as hypertension, diabetes, dyslipidemia, and specific factors such as sodium overload, hyperomocysteinemia, chronic inflammation and oxidative stress, as well as mineral metabolism disturbances. Specifically, hyperphosphatemia and the elevated calcium (Ca) x phosphate product have been associated with an increased risk for the development of vascular calcification and death. Treatment with Ca salts can induce hypercalcemia, increased Ca x phosphate product and Ca overload. Sevelamer substitution for Ca salts has been documented to attenuate the progression of coronary artery and aortic calcification. A possible mechanism explaining this observation could be ongoing Ca loading related to oral Ca ingestion. Treatment with Ca salts could induce Ca overload, particularly in patients dialyzed against a high dialysate Ca (>1.5 mmol/L) solution, which is known to determine a positive dialysis balance. Conversely, an overall negative Ca balance can result from low Ca dialysate use (1.25 mmol/L) when the patients do not receive Ca supplements or vitamin D metabolites. Maintaining normal Ca and phosphate balances remains a primary goal in the management of dialysis patients. Control of hyperphopshataemia should be achieved either using Ca and aluminum-free phosphate binders, such as sevelamer, or Ca salts, alone or in combination, provided that a daily oral elemental Ca intake of 1.5 g is not exceeded.

Calcinosis↗
PubMedDate not supplied

Atherosclerotic renovascular disease: medical therapy versus medical therapy plus renal artery stenting in preventing renal failure progression: the rationale and study design of a prospective, multicenter and randomized trial (NITER).

BACKGROUND: Many studies suggest a major prevalence of atherosclerotic renovascular disease (ARVD), caused by mono or bilateral renal artery stenosis (RAS). Unfortunately, there is no definite therapy to cure this disease to date; therefore, ARVD is burdened by important clinical complications with high social and economic costs. The last few years have seen important advancements in both medical therapy and in interventional radiology (for example, percutaneous transluminal renal artery stenting (PTRS)). All of them could affect, in some way, the natural history of ARVD, but to date the optimal strategy has not been established. METHODS: The protocol of a prospective, multicenter, randomized trial "Nephropathy Ischemic Therapy (NITER)" is presented. It enrolls patients with stable renal failure (glomerular filtration rate (GFR) >or=30 ml/min) and hypertension, and hemodynamically significant atherosclerotic ostial RAS (>or=70%) diagnosed by duplex Doppler (DD) ultrasonography and confirmed by magnetic resonance angiography (MRA). This study aims to evaluate whether medical therapy plus interventional PTRS is superior to medical therapy alone according to the following combined primary endpoint: death or dialysis initiation or reduction by >20% in estimated GFR after 0.5, 1, and 2 yrs of follow-up and an extended follow-up until the 4th year. Medical therapy means drugs to control hypertension, improve dyslipidemia and optimize platelet anti-aggregant therapy. The sample size is estimated in 50 patients per group to achieve a statistical significance of 0.05 in case of a reduction by 50% in the combined endpoints.

Aged↗
PubMedDate not supplied

[Statistical models and multivariable analysis].

Most clinical research can be simplified as an investigation of an input/output relationship. The inputs are called explanatory (independent) variables or predictors and are thought to be related to the outcome, or response (independent) variable. This relationship is usually complicated by other factors related to both the input and the output (presence of confounding) and can vary according to the levels of the other variables (presence of interaction). This input/output relationship is usually described by statistical models that include a fit part and a residual component or difference between the data and the fit. The most popular models are the general linear models, which can be considered the paradigm of all models used in multi-variable analyzes.

Biomedical Research↗
PubMedDate not supplied

[Introduction of the general linear models].

General linear models can be considered the paradigm of all models used in clinical epidemiology. In these models, the independent variables combine in linear fashion to predict the values of the variable response. Since no model predicts the variable response perfectly, an error term is incorporated into the model to acknowledge what remains to be explained after getting a fit to the data. When this error term is normally distributed with constant variance, the linear models are reasonably appropriate to describe the input/output relationship of interest.

Linear Models↗