Selenium in uremia: culprit or bystander?
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Biomedical subjects
Publications and source records attributed to M Bonomini.
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Lipid disturbances have been linked to the progression of chronic renal disease. We examined 52 patients with a creatinine clearance (CCr) of 38.5 +/- 7.9 ml/min due to various nephropathies, on free diet. Bimonthly, over a 12-month period, we assessed: serum creatinine (Cr); CCr; daily urinary urea excretion; urinary protein excretion per unit of residual renal function (UProt/CCr); total, HDL, VLDL and LDL cholesterol; triglycerides; Apo A, Apo B. Chronic renal failure was progressive in 22 patients with a slope of 1/Cr-0.00358 +/- 0.00247, stable in 30 with a slope of 0.00420 +/- 0.00285. Lipid parameters did not differ significantly between the two groups but for the lower Apo A and Apo A/Apo B ratio values in the progressive group. Overall slope inversely correlated with basal CCr; in the progressive patients the slope correlated with the percentage variation of UProt/CCr and only partially with the altered Apo profile.
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The formation of circulating platelet-leukocyte complexes has been observed in a variety of conditions and may be pathophysiologically significant. Platelet-leukocyte interactions in fact facilitate metabolic cooperation and mutual activation, which may be of relevance in many biological processes including inflammation, atherogenesis and hemostasis. During hemodialysis procedure, the series of reactions that can occur upon blood contact with the foreign membrane surface may involve a variety of changes affecting almost every cellular and plasmatic component of the blood. This article reviews the evidence for abnormal interactions between circulating platelets and leukocytes in uremic patients undergoing maintenance hemodialysis and the pathophysiologic implications which may stem from such interactions.
The Italian Registry of Dialysis and Transplantation (RIDT) was born in 1996 under the aegis of the Italian Society of Nephrology, and it is organized as a federation of regional registries. This study aimed to completely revise the epidemiological data collected during the first 5 yrs (1996-2001) of RIDT activity to evaluate the trends of the main epidemiological features. During this period, regional registries were not always able to assure complete and exhaustive information according to RIDT requirements, owing to different levels of organization and functioning. To avoid any possible error in data analysis, information inadequately assessed was refused. The incidence of end-stage renal disease (ESRD) patients on renal replacement therapy (RRT) in Italy has increased from 114 pmp in 1996 to 139 pmp in 2001, that means an increase of 3.5%/yr, corresponding to 5718 patients during 1996 and 8000 patients during 2001. Primary renal diseases (according to the EDTA) in incident ESRD patients are vascular and diabetic nephropathy. Main dialysis modality in incident patients was hemodialysis (HD) (85%), while peritoneal dialysis (PD) was only 15%; pre-emptive transplantation was a very unusual modality. The prevalence of ESRD patients at 31 December was 693 pmp in 1996 and 827 pmp in 2001; among dialysis patients, the corresponding rates were 575 pmp and 657 pmp, respectively. Consequently, the number of dialyzed patients increased, respectively, from 28892 to 37919. The prevalent dialysis modality was bicarbonate dialysis in 74% of cases, followed by hemodiafiltration (HDF) in 15%, continuous ambulatory peritoneal dialysis (CAPD) in 7% and APD in 3%. The gross mortality rate in dialyzed patients was stable during this period, at approximately 14%, the main causes of death being cardiovascular diseases and cachexia.
The phospholipids of the erythrocyte membrane are normally distributed asymmetrically in the double layer with the aminophospholipid phosphatidylserine (PS) present only on the inside of the membrane, since its exposure on the outside has numerous physiopathological consequences. In previous studies we have observed that solutes retained in uremia cause increased exposure of PS on the outer surfaces of the erythrocyte membrane and that this phenomenon may be involved in the uremic physiopathology, reducing erythrocyte survival and encouraging abnormal erythrocyte-endothelium interactions. The capability of the extracorporeal blood clearance treatment in removing the circulating uremic factors, responsible for the increased exposure of PS in red blood cells (RBC), was evaluated in 6 chronic uremic patients treated with haemodialysis (HD) or with on-line HFR in a random cross-over perspective study. The PS removal was evaluated indirectly by measuring the expression of PS in normal RBC incubated with uremic plasma obtained at various moments of the clearance session. The capability of the uremic plasma to expose PS on the RBC of healthy subjects (n-times increase compared to incubation of normal RBC with autologous plasma) was essentially unmodified during HD (3.3 +/- 0.2 pre HD; 3.3 +/- 0.1 after 2 hours; 3.1 +/- 0.2 at the end of the session) but was reduced during HFR (3.1 +/- 0.2 pre HD; 2.3 +/- 0.1 after 2 hours; 1.6 +/- 0.1 at the end of dialysis; p<0.001 at the end of dialysis vs pre and after 2 hours and p<0.001 vs HD at 2 hours and at the end of the session). The reduced capability of the uremic plasma obtained during the HFR session to expose PS in normal RBC, proves removal of the plasmatic uremic factors able to externalize the PS. To assess whether this removal effect is linked to the cartridge containing styrene resin used in the treatment with HFR, samples of ultrafiltrate were taken before and after the cartridge and its capability to express PS on normal RBC was measured. The absolute RBC values expressing PS (%) were (pre-cartridge vs post-cartridge) 8.6 +/- 0.3 vs 3.8 +/- 0.2 after 5 minutes from the start of the session; 3.9 +0.1 vs 1.6 +0.2 halfway through the session; 3.1 +/- 0.1 vs 1.3 +/- 0.66 at the end of the session (p<0.005 pre vs post at all times). Our results show that uremic compounds able to cause increased exposure of PS in RBC can be removed during on-line HFR, mainly thanks to the adsorption properties of the cartridge containing resin. This removal might be of benefit to uremic patients, improving the anaemic condition and reducing abnormal RBC-endothelium interactions which may contribute to endothelial disorder during uremia.
BACKGROUND: Gastroenteric angiodysplasia (AD) is a vascular lesion characterized by vascular ectasias to the submucous sheath of the gastrointestinal tract. Lesions can be flat or raised, isolated or grouped and can break or ulcerate causing acute hemorrhage or, more commonly, chronic bleeding. CASE-REPORT: We describe a 65-year-old patient with a 3-yr history of chronic renal failure (CRF), who gradually developed anemia (hemoglobin (Hb) 10 g/dl) without any episodes of clinically relevant bleeding or any exposure to bleeding risk factors. Blood pressure (BP) was normal and renal function was stable (serum creatinine (Cr) 1.9 mg/dl). Routine laboratory tests showed a slight reduction in serum iron and transferrin saturation and a slightly elevated absolute reticulocyte count. These findings were associated with a positive occult gastrointestinal blood test and raised the clinical suspicion of chronic gastrointestinal blood loss. Oesophagogastro-duodenoscopy and colonoscopy demonstrated an absence of significant lesions, suggesting the need to investigate for a lesion localized in the small intestine. Capsular endoscopy, a recently developed endoscopic technique, particularly suited for small bowel pathology, was performed, and demonstrated the presence of an angiodysplasic lesion, located in the jejunum. CONCLUSIONS: Our case report supports the necessity for a complete clinical and laboratory evaluation of the possible causes of anemia superimposed on relative erythropoietin deficiency in CRF patients. When gastrointestinal blood loss is suspected, the entire gastroenteric tract should be examined to search for the bleeding sites. Our report also demonstrates that AD could be responsible for gastrointestinal bleeding even in mild CRF and not only, as usually reported, in end-stage renal disease (ESRD). Capsular endoscopy offers the unique possibility to determine the bleeding site in the small intestine and appears as an effective diagnostic procedure in CRF patients.
BACKGROUND: Guidelines have indicated the achievement of blood pressure target (BP <130/80 mmHg) as a priority in the conservative treatment of chronic kidney disease (CKD), but the current implementation of these recommendations in clinical practice is unknown. METHODS: We assessed control rates, treatment and clinical correlates of hypertension in 1201 adult non-dialyzed CKD patients followed up by a nephrologist for at least 6 months. RESULTS: Estimated glomerular filtration rate (GFR) was 32 (SD 15) mL/min/1.73 m2. BP target was not achieved in 88% of patients (95% confidence interval (95% CI): 86-90%). In 84% of patients, BP levels were also above the target at the first visit to the nephrology unit 4.5 yrs previously. The risk of not achieving BP target during the nephro-logy follow-up was associated with older age (odds ratio (OR): 1.24, 95% CI 1.06-1.45, p=0.008), diabetes (OR: 2.25, 95% CI 1.20-4.20, p=0.011), and the duration of hypertension (OR: 1.13, 95% CI 1.02-1.24, p=0.016). Among patients with uncontrolled BP, about 70% received multidrug antihypertensive therapy including renin-angiotensin system (RAS) inhibitors; conversely, diuretic treatment was prescribed in a minority of patients (37%), and at insufficient doses in half the cases, despite the insufficient implementation of a low salt diet (18%). CONCLUSIONS: BP target was not reached in most CKD patients routinely seen in the renal clinics. The main barrier to guideline implementation is possibly the inadequate treatment of extracellular volume expansion despite the large prevalence of factors, such as older age and diabetes, which further enhance the intrinsic BP salt sensitivity of CKD.
The Italian Society of Nephrology (SIN) promoted a national survey in order to collect detailed information from all Italian renal and dialysis units. This is the second paper, following the first one which focused on three northwestern regions, aim-ing to present the results of the survey. In this paper, data from the central regions (Abruzzo, Lazio, Marche, Molise and Umbria) are reported. The most relevant findings in the five regions were: A) epidemiology--prevalence of dialysis patients = 742, 781, 731, 814, 768 per million population (pmp); prevalence of transplanted patients = 162, 153, 296, 134, 304 pmp; incidence of dialysis patients = 175, 179, 184, 143, 162; gross mortality of dialysis patients = 12.3, 11.8, 15.9, 13.4, 14.0%; distribution of vascular access in prevalent dialysis patients: arteriovenous fistula = 90, 87, 82, 94, 80%, central venous catheter = 7, 10, 15, 4, 17%; vascular graft = 3, 3 ,3, 2, 3%. B) Structural resources--number of hospital beds = 52, 43, 39, 62, 44; dialysis places = 205, 260, 203, 301, 226. C) Personal resources--renal physicians = 50, 78, 47, 53, 47 pmp; renal nurses = 162, 172, 180, 224, 245 pmp; each renal physician takes care of 15, 10, 16, 15, 17 dialysis patients and each renal nurse cares of 4.6, 4.6, 4.1, 3.6, 3.1 dialysis patients. D) Activity--admission to hospital= 2334, 1689, 2652, 1255, 1377 pmp; renal biopsies = 59, 84, 97, 19, 80 pmp. Despite the differences we find among the regions, most indexes are similar and show a satisfactory level of renal care provided in the central regions examined.
The authors studied the effects of 6 months of zinc therapy on cell-mediated immunity in regular dialysis therapy patients. Serum zinc was significantly enhanced (p less than 0.01) at 2 months. While cells, OKT3, and OKT4 did not show significant variation, but after 6 months of therapy a significant (p less than 0.02) decrease of OKT8 cells, with enhancement of the OKT4/OKT8 ratio, and a significant (p less than 0.01) increase in the Multitest Composite score were found. At the same time, a significant elevation (p less than 0.001) of adenosine triphosphate (ATP), and a reduction (p less than 0.01) of lymphocyte adenosine monophosphate was seen; consequently, energy charge levels increased. Zinc-induced improvement of uremic lymphocyte function is likely mediated by an increase in intracellular ATP.
A causal link between hypercholesterolemia due to elevated plasma concentrations of LDL and VLDL remnants of CAPD patients has been established. The effects of 24 weeks of treatment with Simvastatin, a new HMG coenzyme A-reductase inhibitor (at 20 and 40 mg/day) on serum lipid, lipoprotein, and apolipoprotein A-I and B concentrations, as well as safety parameters and subjective side effects, were evaluated in eight patients (mean duration CAPD 24.80 +/- 7.50 months, age 54.50 +/- 13.70 years). Maximal effects on plasma lipoprotein and apolipoprotein concentrations were achieved after 4 weeks, and remained stable thereafter during the study. Mean fasting plasma cholesterol concentrations decreased from 280.5 +/- 60.2 mg% to 190.2 +/- 40.4 mg/dl (p less than 0.005) (-47%); mean plasma LDL-cholesterol concentrations also decreased from 257.6 +/- 13.4 mg% to 190.5 +/- 15.4 mg/dl (p less than 0.001) (-35%). Apolipoprotein A and B concentrations decreased significantly from 1.78 +/- 0.19 to 1.40 +/- 0.22 g/L (p less than .005) and 1.81 +/- 0.26 to 1.38 +/- 0.20 g/L (p less than .005). These data substantiate the view that Simvastatin is well tolerated and that no serious clinical or adverse laboratory effects have been observed. It appears to be a promising drug for the effective control of hyperlipemia in a large proportion of hypercholesterolemic patients, reducing their cardiovascular morbidity while on CAPD.
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