Corner-Space Renormalization Method for Driven-Dissipative Two-Dimensional Correlated Systems.

We present a theoretical method to study driven-dissipative correlated quantum systems on lattices with two spatial dimensions (2D). The steady-state density matrix of the lattice is obtained by solving the master equation in a corner of the Hilbert space. The states spanning the corner space are determined through an iterative procedure, using eigenvectors of the density matrix of smaller lattice systems, merging in real space two lattices at each iteration and selecting M pairs of states by maximizing their joint probability. The accuracy of the results is then improved by increasing the dimension M of the corner space until convergence is reached. We demonstrate the efficiency of such an approach by applying it to the driven-dissipative 2D Bose-Hubbard model, describing lattices of coupled cavities with quantum optical nonlinearities.

Instability of the Superfluid Flow as Black-Hole Lasing Effect.

We show that the critical velocity of a superfluid flow through a penetrable barrier coincides with the onset of the analog black-hole lasing effect. This dynamical instability is triggered by modes resonating in an effective cavity formed by two horizons enclosing the barrier. The location of the horizons is set by v(x)=c(x), with v(x),c(x) being the local fluid velocity and sound speed, respectively. We compute the critical velocity analytically and show that it is univocally determined by the configuration of the horizons. In the limit of broad barriers, the continuous spectrum at the origin of the Hawking-like radiation and of the Landau energetic instability is recovered.

Multiple sclerosis and celiac disease: is there an increased risk?

Multiple sclerosis and celiac disease are both considered immune-mediated diseases. Recently, improved serological screening methods provided a higher prevalence of celiac disease (CD) in the general population worldwide and also demonstrated gastrointestinal symptoms may be lacking. The aim of this study was to determine the prevalence of (CD) in an unselected group of 95 adults with multiple sclerosis using transglutaminase antibodies. No patients showed pathological values. Different immune and genetic basis between the two diseases may represent crucial insights to explain our results.

Influence of hepatitis B virus virema upon serum aminotransferase activity in dialysis population.

BACKGROUND: The control of the spread of hepatitis B virus (HBV) infection within dialysis units has been one of the major advances in the management of patients with end-stage renal disease (ESRD). However, clinical and biochemical expression of HBV in dialysis patients have not been adequately addressed. Elevated values of serum aminotransferase activity are a sensitive measure of hepatocellular injury, but the role of HBV infection in the development of liver disease among dialysis patients has not been adequately analysed. Also, the clinical impact related to the virological characteristics of HBV in dialysis has not been evaluated. METHODS: Demographic, biochemical and virological data from 727 patients undergoing chronic dialysis in seven dialysis units in northern Italy were collected in order to assess the biochemical consequences related to the presence of HBV infection in this population. We have measured by RT-PCR technology the titers of HBV viremia in HBsAg positive patients receiving dialysis. RESULTS: Univariate analysis showed that AST and ALT values were significantly higher in HBsAg positive/HBV DNA positive than HBsAg negative patients on dialysis; AST, 22.86+/-31.34 vs. 14.19+/-9.7 IU/L (P=0.00001); and ALT, 25.07+/-41.59 vs. 13.9+/-41.59 IU/L (P=0.00001). In the subgroup of HBsAg positive patients, the frequency of detectable HBeAg in serum was 14.9% (7/47). The median value of HBV DNA in patients with detectable HBV DNA in serum was 2.160 x 10(3) copies/mL (range, 2.5 x 10(2)-4 x 10(6) copies/mL). HBsAg positive/HCV positive patients had higher aminotransferase activity than other subgroups (P=0.0001). Multivariate analysis showed a significant and independent association between detectable HBsAg/HBV DNA in serum and AST (P=0.00001) and ALT (P=0.0001) activity AST and ALT levels were lower in dialysis than healthy individuals--this finding persisted in age- and gender-matched comparisons. CONCLUSIONS: The HBV viral load in HBsAg positive patients receiving maintenance dialysis is not high. HBsAg positivity with detectable HBV DNA in serum is a strong and independent predictor of raised aminotransferase activity among dialysis patients. HBsAg positive patients had greater aminotransferase activity than HBsAg negative individuals even if both the groups had mean aminotransferase levels within the normal range considered for healthy population. Clinical trials aimed at identifying the best cut-off value to enhance the diagnostic yield of AST/ALT for detecting HBV in dialysis population are under way.

[Natural history of hepatitis B virus infection in dialysis patients: prospective study by quantitative analysis of HBV viremia]. / Storia naturale dell'infezione da virus dell'epatite B in dialisi: studio prospettico mediante analisi quantitativa della viremia HBV.

BACKGROUND: The natural history of hepatitis B virus (HBV) infection in patients undergoing maintenance dialysis is still unclear. The aim of this study was to measure the HBV viral load (HBV DNA) in a cohort (n=20) of HBsAg positive chronic dialysis patients over a 12-month observation period. METHODS; HBV DNA was measured by the Amplicor HBV MonitorTM Test Kit, an in vitro test that utilizes Polymerase Chain Reaction (PCR) nucleic acid amplification and DNA hybridisation for the quantitative measurement of hepatitis B viral DNA in human serum. Amplicor HBV MonitorTM Test Kit amplifies a sequence in the pre-Core/Core region of the HBV genome with biotinylated and non-biotinylated oligonucleotide primers. RESULTS: There was no significant difference between the median HBV load at the start and the end of the study, 1.85 x 104 HBV copies/ml (percentile 16.84; 6.35 x 102 - 3.5 x 106 HBV copies/ ml) and 8.5 x 103 HBV copies/ml (percentile 16.84; 5.5 x 102 - 6.38 x 105 HBV copies/ml), respectively. These serum HBV DNA levels were lower than those measured by the same test in patients with chronic hepatitis B and normal renal function (Hepatology 2000; 32: 116-23). In the group of HBsAg positive carriers on dialysis, we identified three patterns of HBV viremia over time: 1) patients (n=6) with persistent HBV DNA, 2) those (n=2) with undetectable HBV DNA and 3) those (n=12) with intermittent HBV DNA. Patients with persistent HBV DNA (median, 3.3 x 104 HBV copies/ml; percentile 16.84; 3.5 x 103 - 2.3 x 106 HBV copies/ml) had higher viral HBV load than those with intermittent HBV viremia (median, 1.2 x 103 HBV copies/ml; percentile 16.84; 3.5 x 102 - 2.3 x 104 HBV copies/ml) (p=0.0001). Patients with persistent HBV DNA had higher frequency of serum hepatitis B e antigen (HBeAg) positivity than those showing intermittent and negative HBV DNA, 50% (3/6) vs. 0% (p=0.04). The frequency of serum IgM antibody against hepatitis B core antigen (IgM anti-HBc) was higher in patients with persistent HBV DNA than those having intermittent or negative HBV DNA, 100% (6/6) vs. 33% (4/12), p=0.03. We detected no difference in aminotransferase activity between patients with persistent HBV DNA and those showing intermittent or negative HBV DNA. In the group with persistent HBV DNA, the mean difference between maximum and minimum values of HBV DNA observed in each individual patient was 6.13+/-1.25 decimal logarithm (Log10) and in patients with intermittent HBV DNA 3.87+/-1.49 Log10 (p=0.006). In the entire group, the fluctuations in HBV DNA values over time between and within individuals were not significant. CONCLUSIONS: The viremic HBV load was low and relatively stable over a 12-month follow-up period; three patterns of HBV viremia over time were observed; 30% of the viremic patients had persistent HBV viremia, and those patients had larger viral load and higher frequency of HBeAg and anti-HBc IgM than did patients with intermittent or negative HBV DNA. Prospective studies with longer observation periods are in progress to fully understand the natural history of HBV in these immunosuppressed patients.

[Hepatopathy and hepatitis B virus infection in dialysis patients: cross-sectional study]. / Epatopatia e infezione da virus dell'epatite B nei pazienti in dialisi: studio trasversale.

BACKGROUND: Control of spread of HBV infection in dialysis units in developed countries has been one of the major advances in managing end-stage renal disease (ESRD). Patients with chronic HBV, however, continue to enter the population pool of dialysis patients and transplant candidates. The clinical significance related to the presence of HBsAg in serum of dialysis patients has not been completely understood. AIM AND METHODS: We collected demographic, biochemical and virological data from a large (n=464) population of patients on maintenance dialysis. This was done to assess the influence of virological and host factors on hepatocellular damage, as shown by serum aminotransferase activity. RESULTS: The frequency of HBsAg positivity in our dialysis population was 8.2 % (38/464); the rate of HBsAg positive patients showing HBe antigen was 20.6% (7/34). Twenty-two (84.6%) of 26 HBsAg positive patients showed detectable HBV DNA in serum by Amplicor HBV MonitorTM Test. HBsAg positive patients had serum aminotransferase activity significantly higher than HBsAg negative individuals; GOT (AST) 25.1+/-29.9 vs. 16+/-21.5 UI/L (p=0.001), and GPT (ALT) 31.3+/-52.5 vs. 17.7+/-21.9 UIL (p=0.034). In the subset of HBsAg positive dialysis patients, those in the replicative phase HBeAg positive) had aminotransferase activity higher than HBeAg negative individuals, AST, 42.3+/-43.6 vs. 22.4+/-27.3 UI/L (p=0.097) and ALT, 49.41+/-54.7 vs. 29.17+/-55.76 UI/L (NS) respectively. We did a multivariate analysis by standard least square model on the entire patient group and we found independent and significant association between detectable HBsAg in serum and AST (p=0.0089)and ALT (p=0.0159) values. There was an independent and significant relationship between age and ALT (p=0.01). CONCLUSIONS: In our study group, HBsAg positive patients on dialysis had serum aminotransferase activity significantly higher than that measured in HBsAg negative individuals. However, mean transaminase levels in HBsAg positive patients on dialysis were below the upper limit of normal for the reference range of healthy controls. HBsAg positive dialysis patients with active viral replication showed the greatest liver damage. Studies are in progress to understand further HBV-related liver disease in dialysis population.

[Living-donor kidney transplantation in the cyclosporine era]. / Il trapianto di rene da donatore vivente nell'era della ciclosporina.

BACKGROUND: Renal transplantation is the best possibile form of treatment for chronic renal failure. It offers the patient a longer life expectancy when compared to dialysis. Aim of the study was to evaluate our results with live donor transplantation and the variables that influenced the long-term patient and graft survival. METHODS: 190 patients received a live donor kidney transplantation in our Hospital between 1984 and 2000. Thirty-eight of them received a graft from an HLA identical donor, 130 from an HLA haploidentical donor, 22 from a living unrelated donor (spouse). Fourteen patients underwent a pre-emptive transplantation. Aim of the study was to evaluate which variables could influence the long-term patient and graft survival. RESULTS: The median follow-up of recipients was 69.5 months. The 10-year patient and graft survival were 94.7% and 73.4% respectively. Graft half-life was 29.6 years. Six patients died. Twelve patients lost their graft because of vascular thrombosis and five patients because of rejection within the first six months. After the first year, 11 patients lost their graft because of chronic rejection and 4 after recurrence of the original disease. One hundred and forty-four patients are still under observation, and at the last examination their mean plasma creatinine was 2.0+/-1.1 mg/dl. At univariate statistical analysis the absence of locus DR incompatibility was associated with a trend toward a better long-term survival of both patient and graft (P=0.05), while less than one year of dialysis showed a significantly better survival rate (P < 0.01). CONCLUSIONS: Living-donor transplantation offers an excellent long-term patient and graft survival.

Decreased serum aminotransferase activity in patients with chronic renal failure: impact on the detection of viral hepatitis.

Hepatitis C virus (HCV) infection is common in the dialysis population and patients with chronic renal failure (CRF) not requiring dialysis. HCV is the most important cause of chronic liver disease in dialysis patients; however, its role has been underestimated by the lower aminotransferase activity in the dialysis population. Aminotransferase activity in patients with CRF not requiring dialysis has not been adequately addressed to date. The aim of this study is to investigate whether serum aminotransferase levels in predialysis patients with CRF are less than those obtained in healthy individuals and dialysis patients. We also analyzed the potential association between serum aminotransferase activity and demographic, clinical, and biochemical parameters. Aspartate (AST) and alanine aminotransferase (ALT) activity was greater in antibody to hepatitis C (anti-HCV)-positive than anti-HCV-negative patients with CRF not requiring dialysis (AST, 32.3 +/- 19 versus 18.1 +/- 8 IU/L [P = 0.0001]; ALT, 32.9 +/- 28 versus 17.7 +/- 11 IU/L [P = 0.00001], respectively). Predialysis patients with CRF had lower AST and ALT activity in comparison to healthy individuals (AST, 19.7 +/- 11.2 versus 20.4 +/- 6.8 IU/L [P = 0.00001]; ALT, 19.5 +/- 15.1 versus 21.7 +/- 11.3 IU/L [P = 0.00001], respectively). The difference was much greater after correction for viral markers: AST and ALT levels in hepatitis B surface antigen (HBsAg)-negative anti-HCV-negative predialysis patients with CRF were less than those in the healthy population (AST, 17.9 +/- 8 versus 20.4 +/- 6.8 IU/L [P = 0.00001]; ALT, 17.5 +/- 10 versus 21.7 +/- 11.3 IU/L [P = 0.00001], respectively). Comparison of AST and ALT activity between age-matched healthy and predialysis seronegative CRF groups showed lower AST and ALT values in the study population. HBsAg-negative anti-HCV-negative dialysis patients had lower AST and ALT activity than seronegative predialysis patients with CRF (AST, 16.6 +/- 11.6 versus 17.9 +/- 8 IU/L [P = 0.01]; ALT, 16.3 +/- 9.4 versus 17.5 +/- 10 [P = 0.041], respectively). Multivariate analysis in the predialysis CRF population showed an independent association between AST (P = 0.00001) and ALT (P = 0.00001) activity and anti-HCV positivity, and age was negatively linked to AST (P = 0.011) and ALT levels (P = 0.001). AST level was negatively related to serum creatinine level (P = 0.0001). In conclusion, HCV infection causes significant liver injury in predialysis patients with CRF. These patients have decreased aminotransferase activity compared with the general population. Dialysis patients show lower aminotransferase activity than predialysis patients with CRF. Because serum aminotransferase levels are commonly used to screen for liver disease in the dialysis and predialysis CRF population, recognition of liver damage may be hampered by the reduction in aminotransferase values in these patients. Studies aimed to clarify the pathogenesis of this phenomenon are in progress.

Folate supplementation in peritoneal dialysis patients with normal erythrocyte folate: effect on plasma homocysteine.

The possible role of folate supplementation in reducing hyperhomocysteinemia in dialysis patients has been reported in several recent papers. However, scant data are available for peritoneal dialysis patients; besides, none of these studies investigated either the role of intraerythrocyte folate concentration or the presence of side effects caused by folate administration. Sixty-six peritoneal dialysis patients with hyperhomocysteinemia (>15 micromol/l) and normal folate status (as assessed by erythrocyte folate level >600 nmol/l) were randomly allocated to receive either oral folate (5 mg/day) or no vitamin supplementation. After 2 months of therapy, patients were requested to answer a questionnaire investigating the occurrence of symptoms possibly related to folate supplementation. Twenty-nine treated patients and 30 untreated controls completed the study. In the treated patients, serum and erythrocyte folate increased significantly (p < 0.0001) (respectively from 10.6 +/- 4.9 to 237 +/- 231 nmol/l and from 1,201 +/- 297 to 2,881 +/- 294 nmol/l) to levels at the uppermost limit of detection by laboratory methods. Serum vitamin B(12) levels did not change. Plasma homocysteine levels decreased from 54 +/- 32 to 23 +/- 14 micromol/l after folate supplementation and remained unchanged in the control group. After 4 months of folate therapy, homocysteine concentration was within the normal range in 5 patients (17%) and below 30 micromol/l in the other 21 (72%). Folate therapy resulted in a decrease in homocysteine of more than 50% in 45% of the patients and decrease of more than 20% in a further 38%. No significant symptoms were reported. Thus, serum and erythrocyte folate increase confirms that normal folate levels are inadequate in dialysis patients, even if serum and erythrocyte levels before folate supplementation cannot predict the effect on homocysteine plasma levels.

Serum cardiac troponin I after conventional and minimal invasive coronary artery bypass surgery.

We evaluated myocardial release of cardiac troponin I (cTnI) in patients treated with conventional coronary artery bypass grafting (CABG), which employs extracorporeal circulation, and different kinds of minimal invasive coronary artery bypass grafting (MICABG), a surgical technique where the operation is performed without extra-corporeal circulation. Furthermore, we evaluated the usefulness of serum cTnI measurement to detect perioperative myocardial infarction (PMI) after coronary artery bypass surgery. Thirty-one patients were included: sixteen underwent CABG, fifteen underwent different MICABG and five patients had PMI. Blood specimens for cTnI measurements were collected up to 72 hours after opening the graft. Aortic cross-clamping time was a minor determinant of myocardial damage; on the other side, the trauma during surgery correlated with the number of involved arteries and with the manoeuvre employed to obtain heart dislocation, and appeared a more important determinant of myocardial damage. In patients with PMI, the cumulative release of cTnI was higher than in patients free from PMI; however, only after 24-72 hours we observed significant differences in serum cTnI values, because the increased perioperative values of cTnI complicated the interpretation of the myocardial status and a single cut-off could not be used to exclude PMI.

Homocysteine, vitamin B12, serum and erythrocyte folate in peritoneal dialysis patients.

Plasma homocysteine (tHcy) is an important risk factor for atherosclerosis in dialysis patients. Few data were reported on the prevalence and severity of hyperhomocysteinemia in peritoneal dialysis (PD) patients. In addition, little attention was paid to the search of factors possibly involved in the pathogenesis of hyperhomocysteinemia in these patients. A cross-sectional study was performed in 107 stable PD patients. None of them was given folate or vitamin B12 supplementation before or during the study. Plasma tHcy, serum vitamin B12, serum and erythrocyte folate were measured by immunoenzymatic methods. Genetic analysis of the methylentetrahydrofolate-reductase thermolabile mutation (tMTHFR) was performed in 61 patients. 97% of patients had tHcy levels higher than normal. tHcy was not different between men and women, patients with or without malnutrition, with or without clinically evident atherosclerotic vasculopathy, with or without anemia. tHcy levels were significantly higher in homozygotes for the tMTHFR mutation than in patients carrying the wild type form. Significant univariate correlation was found between hyperhomocysteinemia and time since the start of dialysis, serum and erythrocyte folate and vitamin B12. The best fitted model equation was log tHcy = 108.53 + 0.1606 (duration of dialysis) -1.1053 (s-F) -0.7980 (age) 0.0215 (vitamin B12). Our results agree with those reported by other authors in hemodialysis patients. Despite the large number of PD patients with normal serum vitamin B12 and folate status, the relation between tHcy and vitamin B12 or folate suggests that the supplementation of these vitamins could be useful irrespective of their serum levels, especially in younger patients or in those treated for a long period of time with peritoneal dialysis.

Healing of diabetes and vascular ulcers on switching from peritoneal dialysis to hemodialysis.

Vascular complications are the main problem in diabetic patients and can be worsened by continuous ambulatorial peritoneal dialysis (CAPD). A 46-year old woman with a family history of diabetes progressively developed hyperglycemia and subsequently lower limb ulcers after beginning CAPD. Hypertonic bags were required to control fluid balance. On account of the severe and painful ulcers, the patient was changed to hemodialysis. Within a few weeks her diabetes improved and the vascular ulcers healed completely.

Preliminary evaluation of incremental peritoneal dialysis in 25 patients.

BACKGROUND: Incremental dialysis has been suggested for patients with some residual renal function. However, very little published clinical data exist on the feasibility of this schedule. OBJECTIVES: To assess feasibility of incremental dialysis, with regard to its effect, complications, and impact on quality of life. DESIGN: Pilot prospective study, not controlled. SETTING: Nephrology division, public clinical research hospital. PATIENTS: Twenty-five patients (19 men, mean age 61+/-13 years, body weight 63+/-11 kg) began peritoneal dialysis (the first treatment of uremia) with a single nightly exchange lasting 10 hours or 2 daily exchanges over 12 hours according to creatinine clearance and Kt/N. Patients gave informed consent and reported their work activity, degree of rehabilitation, and their quality of life by answering a questionnaire prepared for this purpose. OUTCOME MEASURES: Survival rate, complications related to peritoneal dialysis, and residual renal and peritoneal clearances. RESULTS: During the study period no patient died. Complications related to dialysis were peritonitis (0.41 episodes/year) and exit-site infection (0.32 episodes/year). All patients continued to work with full rehabilitation and considered 1 or 2 exchanges per day less troublesome than 3 or 4. CONCLUSIONS: Incremental dialysis is well accepted by patients and staff. This technique does not involve a high risk of complications and is economical. Therefore incremental dialysis is feasible.

Sleep disorders in peritoneal and haemodialysis patients as assessed by a self-administered questionnaire.

Sleep disorders have been reported as a frequent problem in dialysis patients. However, only one paper has compared the prevalence and possible causes of this complication in peritoneal (PD) and haemodialysis (HD) patients. We surveyed 84 PD and 87 HD patients about disordered sleep using a self-administered questionnaire. Forty-nine percent of PD and 56% of HD patients reported problems sleeping. These problems were rated as severe by 29 PD and 22 HD patients. Type of disturbances involved delayed sleeping (13 PD and 32 HD, p < 0.005), interrupted sleep (32 PD and 44 HD) and early morning awakening (25 PD and 37 HD). The number of hours of sleep varied widely among patients: it was 5 and 21 minutes in PD patients with sleep disorders and 7 and 37 min in PD pts without such problems. No statistically significant relationship was evidenced between sleep disorders and age, sex, body weight, obesity, duration of dialysis, dialysis dose, self-assessed sadness, anxiety, worry, pain, pruritus, dyspnoea, restless leg syndrome, use of cigarettes, caffeine, or sleeping pills. In conclusion, sleep disorders are a frequent problem in both PD and HD patients. Apparently the relationship with demographics, dialysis dose, lifestyle and personality traits is poor. The possible role of other causes should be investigated.

Homocysteine, vitamin B12, and serum and erythrocyte folate in peritoneal dialysis and hemodialysis patients.

BACKGROUND: Plasma homocysteine (Hcy) is an independent risk factor for cardiovascular disease. High levels of plasma Hcy have been observed in end-stage renal disease patients. Few studies have compared peritoneal dialysis (PD) and hemodialysis (HD) patients and few data are available on erythrocyte folate (ery-F) levels in dialysis patients. OBJECTIVES: To evaluate plasma Hcy concentrations, vitamin B12 (B12), and folate status in dialysis patients; to analyze the possible causes of high Hcy levels; to follow up changes in folate and B12 concentrations after 6 months. DESIGN: A cross-sectional observational study. SETTING: Nephrology division and laboratory of hematology in a university and clinical research hospital. PATIENTS: The study included 82 patients treated with PD for 37 + 37 months and 70 patients treated with HD for 136 + 95 months. LABORATORY METHODS: Plasma Hcy was measured by the immunoenzymatic IMx Hcy FPIA method (Abbott Laboratories, Diagnostic Division, Abbott Park, IL, U.S.A.), serum folate (s-F) and ery-F by the Stratus folate fluorometric enzyme-linked assay, and B12 by the Stratus vitamin B12 fluorometric enzyme-linked assay (DADE-Behring, Newark, DE, U.S.A.). RESULTS: Ninety-six percent of PD and 97% of HD patients had Hcy levels above the cutoff (13.5 micromol/L). Homocysteine level was higher in HD than in PD patients, while the prevalence of hyperhomocysteinemia was similar with the two techniques. Erythrocyte folate was significantly higher in PD (1333 +/- 519 pmol/L) than in HD (1049 +/-511 pmol/L, p < 0.01). Statistically significant correlations were observed between Hcy and B12, s-F, ery-F, and dialysis duration. Multivariate analysis showed a strong correlation between s-F and Hcy. After 6 months there were no differences in Hcy, B12, s-F, and ery-F levels. CONCLUSIONS: Plasma Hcy levels were high in more than 95% of our dialysis patients, with no relation to the type of dialysis. Vitamin B12 and folate were normal in the majority of our patients. However, serum folate was the major determinant of Hcy levels. Such a relation between Hcy and folate suggests that levels of folate within the reference interval are inadequate for dialysis patients.

Folate measurements in patients on regular hemodialysis treatment.

Patients on regular hemodialysis treatment may develop megaloblastic anemia caused by folate deficiency, but whether folate supplementation is required is still controversial, particularly during erythropoietin administration. Erythrocyte folate concentration is a better indicator of folate status than serum folate, although the latter is the variable generally measured. We measured serum and erythrocyte folate in blood samples from 112 regular hemodialysis patients (57 men, 55 women, 50 treated with erythropoietin, and 62 not) by Stratus Folate immunoenzymatic assay (Dade). Patients with very low serum (<2.87 ng/mL) but normal erythrocyte folate were reinvestigated 4 months later without receiving folate supplementation meanwhile. Serum folate concentrations were 0.48 to 12.76 ng/mL (median, 3.40) and erythrocyte folate 0.19 to 1.85 microg/mL (median, 0.42). Only 37% serum folate values were in the relevant reference interval compared with 80.2% erythrocyte folate values (3.08 to 17.65 ng/mL and 0.24 to 0.64 microg/mL, respectively). A significant correlation was found between serum and erythrocyte folate concentrations, without clinical relevance caused by the wide scatter around the regression line. Serum and erythrocyte folate did not vary significantly between patients given erythropoietin and those not so treated. The folate status of the 24 patients with very low serum folate was almost unchanged 4 months later. According to the serum folate test, 63% of patients needed folate supplementation, whereas the erythrocyte folate test, a better indicator of folate status, suggested that only 1.8% of patients needed folate supplementation. Erythropoietin therapy appears not to be an indication for standard folate supplementation in hemodialysis patients.

Renal effects of dietary supplementation with fish oil in cyclosporine-treated liver transplant recipients.

Nephrotoxicity is the main untoward effect of cyclosporine (CsA) treatment. Experimental and clinical data suggest that dietary supplementation with fish oil may lessen cyclosporine nephrotoxicity, possibly by lowering renal thromboxane (Tx) production. We have studied the renal effects of a daily supplementation for 2 months of 12 g fish oil (18% C20:5 n-3 eicosapentaenoic acid [EPA] and 12% C22:6 n-3 docosahexanoic acid [DHA]) in a placebo-controlled (12 g corn oil), prospective, randomized, double-blind study of stable CsA-treated liver transplant recipients. Thirteen patients ingested corn oil capsules and 13 fish oil. Compliance with dietary regimen was confirmed by fatty acid chromatography that showed increased plasma concentrations of EPA (from 0.4 +/- 0.02% to 4.6 +/- 0.5%, P < .0001) and DHA (from 1.8 +/- 0.2% to 3.9 +/- 0.1%, P < .0001) in the fish oil group and increased plasma concentration of linoleic acid (C18:2 n-6) in the corn oil group (from 25 +/- 2% to 28.4 +/- 2%, P < .001). At the end of the 2 months of the study, in the fish oil group the effective renal plasma flow increased by 22% (P = .012), the glomerular filtration rate increased by 33% (P = .057), the renal blood flow increased by 17% (P = .024), and the calculated total renal vascular resistances decreased by 20% (P = .034). In contrast, none of these parameters changed in the corn oil group. The renal functional reserve determined during L-arginine infusion, plasma renin activity (PRA), and plasma aldosterone (PA) remained unchanged during the study in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of gastric acid secretion on intestinal phosphate and calcium absorption in normal subjects.

BACKGROUND: Phosphate-induced hyperparathyroidism still represents an intriguing problem in dialysis patients. Postprandial hyperphosphataemia is considered to be the main stimulus to parathyroid hyperfunction, and therefore many efforts have focused on the use of phosphate binders to prevent phosphate absorption. METHODS: We investigated whether the pH-mediated gastric ionization of calcium phosphate dietary salts is necessary for its intestinal absorption. In eight normal subjects we measured 24-h urinary calcium phosphate excretion and the postprandial blood calcium phosphate profile after a meal containing 1 g of calcium and 2 g of phosphate salts in a crossover placebo-omeprazole study. On two occasions the subjects received either placebo or omeprazole 60 mg/day 2 days before and during the day test. RESULTS: Serum gastrin levels were measured as an indicator of achlorhydria and were 13.7 +/- 1 pg/ml after placebo and 30.4 +/- 4.7 after omeprazole (P < 0.003). Postprandial plasma phosphate profiles were not significantly different between the two studies (+36 +/- 8% after placebo and +24 +/- 8% after omeprazole, NS), while plasma calcium increased by +6.1 +/- 1% after placebo and decreased by -4.2 +/- 0.7% after omeprazole (P < 0.01). The 24-h urinary phosphate excretion was 1068 +/- 85 mg after placebo and 773 +/- 55 after omeprazole (P < 0.002), while the 24-h urinary calcium excretion was 360 +/- 21 after placebo and 238 +/- 15 after omeprazole (P < 0.0001). A negative relationship was observed between absolute changes in plasma gastrin and those in urinary calcium (P < 0.009) and phosphate (P < 0.05). CONCLUSIONS: The inhibition of gastric acid secretion by omeprazole significantly reduces both urinary phosphate and calcium excretion after an oral load. The behaviour of the postprandial calcium-phosphate plasma profile suggests that gastric acid inhibition is more effective in reducing calcium rather than phosphate dietary salts absorption in normal subjects.