A retrospective view of the relationship of soluble Fas with anemia and outcomes in chronic kidney disease

BACKGROUND

Anemia is common in chronic kidney disease (CKD) and is associated with outcomes. In addition, serum soluble Fas (sFas) levels are related to anemia and erythropoietin (EPO) resistance.

OBJECTIVES

Firstly, to compare clinical data and serum levels of sFas, EPO, and pro-inflammatory markers between patients with non-dialytic CKD (NDD-CKD) and healthy subjects. Subsequently, to compare and evaluate the relationship of serum EPO, sFas levels with anemia, and outcomes in patients with NDD-CKD over a long follow-up period.

METHODS

We performed a retrospective study in 58 NDD-CKD patients compared with 20 healthy subjects on complete blood count, kidney function, serum EPO, sFas, and inflammatory markers (CRP, IL- 6, and IFN-γ) at baseline. We then compared the same baseline data between patients with NDD-CKD who evolved to anemia and those who did not have anemia over the follow-up. We also evaluated the frequency of outcomes in patients with CKD with higher sFas levels. Finally, we performed a multivariate analysis of factors associated with CKD anemia.

RESULTS

There were lower eGFR and Hb but higher serum inflammatory markers, sFas levels, sFas/eGFR, and EPO/Hb ratios in patients with NDD-CKD. Comparatively, on the other hand, NDD-CKD patients with anemia had lower eGFR but were older, had more diabetes, and had higher sFas/ eGFR, EPO/Hb ratios, and serum levels of IL-6 and sFas than NDD-CKD without anemia for an extended period. In addition, there was an association in a multivariate analysis of diabetes, age, and sFas levels with kidney anemia. Furthermore, there were higher frequencies of outcomes in increased serum sFas levels.

CONCLUSION

As an elective risk factor, serum sFas levels, in addition to age and diabetes, were independently associated with kidney anemia for an extended period. Thus, more studies are necessary to analyze the proper relationship of sFas with kidney anemia and its outcomes and therapy in CKD.

Soluble Fas affects erythropoiesis in vitro and acts as a potential predictor of erythropoiesis-stimulating agent therapy in patients with chronic kidney disease

Serum soluble Fas (sFas) levels are associated with erythropoietin (Epo) hyporesponsiveness in patients with chronic kidney disease (CKD). Whether sFas could predict the need for erythropoiesis-stimulating agent (ESA) usage and its influence in erythropoiesis remain unclear. We evaluated the relation between sFas and ESA therapy in patients with CKD with anemia and its effect on erythropoiesis in vitro. First, we performed a retrospective cohort study with 77 anemic patients with nondialysis CKD. We performed in vitro experiments to investigate whether sFas could interfere with the behavior of hematopoietic stem cells (HSCs). HSCs were isolated from umbilical cord blood and incubated with recombinant sFas protein in a dose-dependent manner. Serum sFas positively correlated with Epo levels (r = 0.30, P = 0.001) but negatively with hemoglobin (r = -0.55, P < 0.001) and glomerular filtration rate (r = -0.58, P < 0.001) in patients with CKD at baseline. Elevated sFas serum levels (4,316 ± 897 vs. 2,776 ± 749, P < 0.001) with lower estimated glomerular filtration rate (26.2 ± 10.1 vs. 33.5 ± 14.3, P = 0.01) and reduced hemoglobin concentration (11.1 ± 0.9 vs. 12.5 ± 1.2, P < 0.001) were identified in patients who required ESA therapy compared with patients with non-ESA. Afterward, we detected that the sFas level was slight correlated with a necessity of ESA therapy in patients with nondialysis CKD and anemia. In vitro assays demonstrated that the erythroid progenitor cell frequency negatively correlated with sFas concentration (r = -0.72, P < 0.001). There was decreased erythroid colony formation in vitro when CD34+ HSCs were incubated with a higher concentration of sFas protein (1.56 ± 0.29, 4.33 ± 0.53, P < 0.001). Our findings suggest that sFas is a potential predictor for ESA therapy in patients with nondialysis CKD and that elevated sFas could affect erythropoiesis in vitro.

Chronic kidney disease induces inflammation by increasing Toll-like receptor-4, cytokine and cathelicidin expression in neutrophils and monocytes

TLR expression in neutrophils and monocytes is associated with increased cytokine synthesis, resulting in increased inflammation. However, the inflammatory pathway related to TLR and cathelicidin expression in these cells from CKD patients is unclear. To evaluate TLR4, cathelicidin, TNF-α, IL-6, IL-10 and MCP-1 expression in neutrophils and monocytes from HD and CKD patients. Blood samples were drawn from 47 CKD and 43 HD patients and 71 age and gender-matched healthy volunteers (CONT). TLR4 was analyzed using flow cytometry. Cathelicidin, TNF-α, IL-6, IL-10 and MCP-1 were analyzed via ELISA.TLR4 expression in neutrophils was higher in HD patients than in stage 3 and 4 CKD patients. In these cells, we observed a positive correlation between TLR4 and cathelicidin, TNF-α, IL-6, IL-10 and MCP-1 levels. In monocytes, TLR4 expression was significantly higher in CKD 3 and 4 groups than in the control and HD groups and positively and negatively correlated with IL-6 and MCP-1 and cathelicidin, respectively. TNF-α, IL-6 and MCP-1 serum levels were higher in HD and CKD patients than in control. Cathelicidin and IL-10 levels were only higher in HD patients. IL-6 serum levels were positively correlated with all cytokines, and cathelicidin was negatively correlated with MCP-1 (r = - 0.35; p < 0.01) and positively correlated with IL-10 (r = 0.37; p = 0.001). These results suggest that a uremic environment induces high TLR4, cathelicidin and cytokine expression and may increase inflammation. Thus, future studies should be conducted to evaluate whether TLR4 and cathelicidin should be targets for anti-inflammatory therapeutic strategies.

TNF-α depuration is a predictor of mortality in critically ill patients under continuous veno-venous hemodiafiltration treatment

INTRODUCTION

Critically ill patients with acute kidney injury (AKI) present high mortality rates. The magnitude of inflammatory response could determine the prognosis of such patients. Continuous renal replacement therapy (CRRT) may play an important role in removing inflammatory mediators in patients with AKI.

AIM

To investigate whether the magnitude of inflammatory mediator's removal is associated with mortality among critically ill patients on CVVHDF, a CRRT modality.

METHODS

This study consisted of 64 critically ill patients requiring CVVHDF. Plasma levels of C3a, TNF-α, IL-10, IL-6, IL-1β, sTNFRI and sTNFRII were determined by enzyme-linked immunosorbent assay (ELISA) at the beginning of CVVHDF and after 24h (outlet). Clearance of cytokines during the first 24h of CVVHDF was calculated. Clinical and laboratory data were acquired from patient's records data.

RESULTS

Mean age of patients requiring CVVHDF was 63years, 67.2% were men and 87.3% were Caucasian. Thirty-five (35) patients (54.7%) died. Comparing non-survivors with the group of survivors we observed higher incidence of sepsis (68.6 versus 37.9%, p<0.05), higher APACHE II score (34.8±7.6 versus 29.2±7.1, p<0.05) and higher lactate levels (23.2±17.6 versus 16.4±6.6, p<0.05). According to the inter-tertile range of TNF-α clearance (ITR1 (<0.54); ITR2 (0.54-2.93); ITR3 (>2.93)) we found that those patients with higher TNF-α removal by RRT (ITR3) had a better survival. Multivariable analysis showed that lower clearance of TNF-α remained independently associated with high mortality after adjustment for sex, age, use of vasoactive drugs, APACHE II score sepsis, creatinine and lactate before CVVHDF (HR: 0.179, 95% IC: 0.049-0.661, p<0.01).

CONCLUSION

The attenuation of inflammatory response may be related to the lower mortality observed on those patients with higher TNF-α removal by CVVHDF.

Abstract 228: Apolipoprotein E (ApoE) Genetic Polymorphism Modulation Of Endothelial Dysfunction In Hypertensive Patients Is Determined By Renal Function

INTRODUCTION: ADMA, an endogenous inhibitor of nitric oxide synthase, is an independent marker of progression of renal dysfunction, vascular complications and death. Overexpression of the ADMA degrading enzyme dimethylarginine dimethylaminohydrolase 1 (DDAH1) ameliorates atherosclerosis in genetic ApoE deficient mice. Once ApoE polymorphism is a key player on lipid metabolism, it is possible that it brings on individual susceptibility to endothelial dysfunction.

OBJECTIVE: The aim of this study was to assess the effect of the ApoE genetic polymorphism on ADMA levels in a cohort of hypertensive patients stratified by renal function.

PATIENTS AND METHODS: Patients were stratified into 3 groups according to GFR using the CKD-EPI: I > 60ml/min, II ≤ 60 ml/min and > 15 ml/min, and III ≤ 15 ml/min. HPLC was used for the measurement of ADMA. Polymorphic ApoE analysis performed by PCR amplification and allele frequency compared in each group between first and third tertile of ADMA as epidemiological, clinical and laboratorial characteristics. Statistical analysis performed using the software IBM SPSS Statistics 20.0.

RESULTS: Mean age of the patients was 60.1± 14.1 years, 318 (50.7%) were male, mean BMI was 28.0 ± 5.3, 396 (63.2%) were Caucasians, 244 (38.9%) had DM, 316 (50.4%) had dyslipidemia, 223 (35.6%) had cardiovascular disease (CVD). Groups were composed respectively of 189, 229 and 202 patients. E2 allele was present in 67 (10.7%) patients, E3 allele in 588 (93.8%), E4 allele in 116 (18.5%). In group III, the frequency of E4 allele of ApoE was lower in the third tertile of ADMA (p = .000, Pearson Chi-Square). This link remained significant even after control for confounders like age, sex, BMI, DM, CVD, PCR and LDL (OR 0.127, CI: 0.35 - 0.468, p = .002).

CONCLUSION: ApoE E4 allele independent association with lower levels of ADMA is pronounced among those patients with advanced stage of renal disease. This association may represent an unknown genetic pathway that modulates ADMA levels on this population.

Abstract 468: Diversity of Apolipoprotein E genetic polymorphism significance on cardiovascular risk is determined by the presence of Metabolic Syndrome among hypertensive patients

INTRODUCTION: Hypertension has a significant relevance as a cardiovascular risk factor. A consistent increase on world’s Metabolic syndrome (MetS) incidence has been associated with an epidemic cardiovascular risk in different populations. Dislipidemia plays a major role determining the epidemic CV burden attributed to MetS. Apolipoprotein E (ApoE) is involved on cholesterol and triglycerides metabolism regulation. Once ApoE polymorphism may influence lipid metabolism, it is possible that it brings on individual susceptibility consequences for the development of MetS and cardiovascular risk.

OBJECTIVE: To measure the discriminatory power of ApoE polymorphism in determining the cardiovascular risk stratification based on the presence MetS in a cohort of hypertensive patients.

PATIENTS AND METHODS: It was enrolled 401 patients, divided in two groups, classified by MetS presence (IDF criteria): Group 1: 275 patients with MetS (MetS +) and Group 2: 126 patients without Mets (MetS -). Patient’s data were collected by clinical evaluation, physical exam, file reviews and laboratory testing. Polymorphic ApoE analysis was performed by PCR amplification. Groups were compared on clinical and laboratorial characteristics as well as allele and genotype distribution in relation to ApoE polymorphism. Prevalence of CVD, in relation to Mets presence, was analysed based on allele 4 prevalence.

RESULTS: The results evidenced 186 men (47,4%), 62,1% whites, 44,1% diabetics and 11,5% of patients were smokers. Mean age was 64,0±12,0 years. When genotypic distribution was analyzed, E3/3 genotype and E3 allele frequency were more prevalent. Among patients with MetS, we observed an independent association between CVD prevalence and allele E4 frequency(OR 2.42(1.17-1.5, p<0,05)). On the contrary, in those without MetS, there was lesser CVD burden in E4 allele carriers(OR 0,14(0,02-0,75)). These associations remained significant even after confounding factor corrections.

CONCLUSION: The results presented show that association between ApoE gene and CVD maybe modulated by de presence of MetS, with an increased CV burden observed among E4 carriers with the Syndrome. On the opposite way, E4 carriers without visceral obesity had a lesser prevalence of CVD.

Tumour necrosis factor-α plus interleukin-10 low producer phenotype predicts acute kidney injury and death in intensive care unit patients

Genetic polymorphism studies of cytokines may provide an insight into the understanding of acute kidney injury (AKI) and death in intensive care unit (ICU) patients. The aim of this study was to investigate whether the genetic polymorphisms of -308 G < A tumour necrosis factor (TNF)-α, -174 G > C interleukin (IL)-6 and -1082 G > A IL-10 may predispose ICU patients to the development of AKI and/or death. In a prospective nested case-control study, 303 ICU patients and 244 healthy individuals were evaluated. The study group included ICU patients who developed AKI (n = 139) and 164 ICU patients without AKI. The GG genotype of TNF-α (low producer phenotype) was significantly lower in the with AKI than without AKI groups and healthy individuals (55 versus 62 versus 73%, respectively; P = 0·01). When genotypes were stratified into four categories of TNF-α/IL-10 combinations, it was observed that low TNF-α plus low IL-10 producer phenotypes were more prevalent in patients with AKI, renal replacement therapy and death (P < 0·05). In logistic regression analysis, low TNF-α producer plus low IL-10 producer phenotypes remained as independent risk factors for AKI and/or death [odds ratio (OR) = 2·37, 95% confidence interval (CI): 1·16-4·84; P = 0·02] and for renal replacement therapy (RRT) and/or death (OR = 3·82, 95% CI: 1·19-12·23; P = 0·02). In this study, the combination of low TNF-α plus low IL-10 producer phenotypes was an independent risk factor to AKI and/or death and RRT and/or death in critically ill patients. Our results should be validated in a larger prospective study with long-term follow-up to emphasize the combination of these genotypes as potential risk factors to AKI in critically ill patients.

Ascorbic acid reduces gentamicin-induced nephrotoxicity in rats through the control of reactive oxygen species

BACKGROUND & AIM

Oxidative stress has been implicated in the pathophysiology of many forms of acute renal failure. The aim was examine the effect of vitamin C on oxidative stress and its relationship with nitric oxide on gentamicin-induced nephrotoxicity in rats.

METHODS

We utilized 32 Wistar rats allocated in four groups of eight animals each: control (CTL), vitamin C (VIT C), gentamicin (GENTA), and GENTA + VIT C; all groups were treated during seven days.

RESULTS

Serum urea and creatinine, serum and renal tissue malondialdehyde, blood superoxide anion and hydrogen peroxide in GENTA were increased vs CTL and vs VIT C, and decreased in GENTA + VIT C vs GENTA (all P < 0.05). Serum nitric oxide increased in GENTA vs CTL and vs VIT C, and reduced in GENTA + VIT C vs GENTA (P < 0.001). Urinary nitric oxide was reduced in GENTA vs CTL and vs VIT C and increased in GENTA + VIT C vs GENTA (P < 0.001). Severe degeneration of proximal tubules was present in GENTA, but only mild lesions were observed in GENTA + VIT C.

CONCLUSION

This study suggests that VIT C is a valuable tool to protect against GENTA-induced nephrotoxicity, by reducing reactive oxygen species and increasing the nitric oxide.

Postprandial interleukin-6 response in elderly with abdominal obesity and metabolic syndrome

OBJECTIVE

The aim of this study is to evaluate the contribution of central obesity to inflammatory responses in the postprandial state in elderly patients with and without metabolic syndrome (MetS).

MATERIAL/METHODS

We evaluated 80 elderly individuals who were distributed into three groups: MetS, abdominal obesity (AbObes) and Control, according to ATPIII criteria. Interleukin-6 (IL-6) serum concentration was measured at 0, 2, 4 and 6 hours after the ingestion of a physiological meal without an overload of fat.

RESULTS

Serum IL-6 increased 6 hours after the meal in all of the groups (P<0.001). Comparing the groups, there was no difference in the area under the curve (AUC) of IL-6 in the postprandial state. There was a correlation between the 6-hour changes in the concentrations of IL-6 and the homeostasis model assessment of insulin resistance (HOMA-IR) (r = 0.25, P<0.05).

CONCLUSION

In this study, differences in abdominal circumference (AC) have not determined a different behavior of IL-6 in the postprandial state, despite the correlation between AC and IL-6. However, we found that, in the elderly, there is a rise in serum IL-6 at 6 hours.

Effects of spermidine and p-cresol on polymorphonuclear cell apoptosis and function

Polymorphonuclear leukocytes (PMNs) from chronic kidney disease (CKD) patients display accelerated apoptosis and dysfunction, which may predispose CKD patients to infections. In this study, we investigated the effect of spermidine and p-cresol on apoptosis and function on PMN from healthy subjects. We measured the effect of spermidine and p-cresol on apoptosis, ROS production unstimulated and stimulated (S. aureus and PMA) and expression of CD95, caspase 3, and CD11b on PMN. After incubation with p-cresol and spermidine, we did not observe any changes in apoptosis, viability or expression of caspase 3 and CD95 in PMN from healthy subjects. PMN incubated for 10 minutes with spermidine demonstrated a significant reduction in spontaneous, S. aureus and PMA-stimulated ROS production. p-cresol induced a decrease in PMA-stimulated ROS production. Spermidine and p-cresol also induced a decrease in the expression of CD11b on PMN. Spermidine and p-cresol decreased the expression of CD11b and oxidative burst of PMN from healthy subjects and had no effect on PMN apoptosis and viability.

Clinical implications of initial renal function after deceased donor transplant

The aim of this study was to investigate whether slow graft function (SGF) after transplantation of deceased-donor kidneys affected the prevalence of anemia or the glomerular filtration rate (GFR). We retrospectively evaluated the records of 534 kidney transplant patients who were classified based on their initial renal function, namely, immediate graft function (IGF), slow graft function (SGF), or delayed graft function (DGF). Among the 534 kidney transplant patients studied, the occurrences of each condition were IGF 104, SGF 133, and DGF 297. Six months after transplantation, a greater percentage of DGF patients were anemic compared with the others (P = .028). However, at 12 months after transplantation, SGF patients showed more anemia than the IGF group. DGF and SGF patients displayed similar GFR values at 18 and 24 months after transplantation. However, IGF patients displayed higher GFRs, even when subjects who experienced acute rejection episodes were censored (P = .004). The incidence of acute rejection episodes was similar among SGF and DGF patients. Patients displaying SGF after deceased-donor transplantation showed a greater tendency to be anemic than those displaying IGF. This study also suggested that SGF patients were at risk for acute rejection episodes and/or significantly reduced kidney function as measured by GFR.

Infectious complications after deceased kidney donor transplantation

BACKGROUND

Despite improvements in immunosuppressive therapy, infections remain a complication of renal transplantation that is associated with increased morbidity and graft rejection. The aim of this study was to evaluate the relationship between initial renal function after deceased donor transplantation and viral infections.

METHODS

We included patients 18 years and older who received a deceased donor transplantation between January 1995 and December 2004. They were divided into 2 groups: cases from 1994 to 1999, versus from 2000 to 2004. Initial renal function was classified as immediate (IGF), slow (SGF), or delayed (DGF). Infections were classified according to Centers for Disease Control and prevention standards.

RESULTS

Among 534 patients, SGF and DGF patients who underwent immunosuppression between 2000 and 2004 show a higher infection rate than IGF patients (P = .005). SGF patients showed a higher incidence of tissue-invasive cytomegalovirus disease (P < .001). Second episodes of viral infections were more common among all patients in this period. However, DGF patients were more susceptible to second episodes of viral infection. In the first group, OKT3 use (P = .013) and donor age (P = .012) were the major risk factors associated with viral infections whereas in the second group, thymoglobulin use (P = .002), acute rejection episode (P = .003), and anemia (P = .044) were the risk factors for viral infection.

CONCLUSION

Initial renal function after deceased donor transplantation was correlated with viral infection. DGF patients had a higher risk for second infection episodes. SGF patients had a higher risk for tissue-invasive cytomegalovirus infection.

Association of endothelial nitric oxide synthase gene intron 4 polymorphism with end-stage renal disease

BACKGROUND

Nitric oxide (NO) released from endothelial cells is related to the maintenance of physiological vascular tone. The impairment of endothelial NO generation brought about by gene polymorphism is considered one of the deterioration factors in progressive renal disease. In the endothelial nitric oxide synthase (eNOS) intron 4 polymorphism, the presence of the aa genotype has been associated with cardiovascular and renal disease. The aim of this study was to investigate the presence of eNOS gene intron 4 polymorphism in patients with end-stage renal disease (ESRD).

METHODS

A total of 114 patients and 94 controls were studied. DNA specimens were extracted from blood and amplified by polymerase chain reaction. The alleles were separated by agarose gel electrophoresis. Genotype distribution and allele frequencies were compared between groups using the chi-squared test.

RESULTS

Statistical analysis revealed that the frequency of the eNOS4 genotype aa was significantly different in ESRD patients and in controls (P=0.016, OR=2.07, CI 95%: 1.14-3.74). There was also a statistically significant difference between ESRD patients and controls regarding allele carriers (P=0.004; OR=2.26; CI 95%: 1.29-3.96). When the frequencies of allele carriers in the diabetic nephropathy group and in the control group were compared, a significant difference was found (P=0.034, OR=2.28; CI 95%: 1.04-5.00).

CONCLUSION

This study showed a strong correlation between eNOS4a polymorphism and end-stage renal disease.

Serum and cellular interleukin-6 in haemodialysis patients: relationship with energy expenditure

BACKGROUND

Inflammation is a highly prevalent condition among end-stage renal disease (ESRD) patients and it has been implicated with several metabolic derangements. Considering the harmful effect of hypermetabolism on nutritional status and clinical outcomes of ESRD patients, we aimed to investigate the relationship between proinflammatory cytokine interleukin-6 (IL-6) and energy expenditure in this population.

METHODS

This cross-sectional study enrolled 80 adult haemodialysis patients for the evaluation of serum IL-6 and energy expenditure. The production of IL-6 by peripheral blood mononuclear cells (PBMCs) (spontaneous and endotoxin-stimulated production) was examined in a subgroup of 30 haemodialysis patients and in 11 healthy control subjects. IL-6 was measured by immunoenzymatic assay. The resting energy expenditure was evaluated by means of indirect calorimetry. Body composition was assessed by bioelectrical impedance analysis and skinfold thicknesses.

RESULTS

Serum IL-6 [6.3 (2.2-163.5) pg/ml] correlated positively with age (R = 0.26; P = 0.02) and C-reactive protein (R = 0.31; P < 0.01). Resting energy expenditure correlated positively with lean body mass (R = 0.68; P < 0.001) and BMI (R = 0.44; P < 0.001), and negatively with Kt/V (R = -0.37; P < 0.01). In the multivariate analysis, controlling for age and lean body mass, serum IL-6 was positively associated with resting energy expenditure (n = 80; beta = 2.4; P = 0.01). The production of IL-6 by PBMCs did not reach statistically significant differences between patients and controls [spontaneous production 6541 (96-7739) pg/ml vs 3410 (50-7806) pg/ml, respectively; and stimulated production 6530 (579-7671) pg/ml vs 5304 (1527-7670) pg/ml, respectively]. IL-6 secreted by monocytes showed no association with either serum IL-6 or resting energy expenditure.

CONCLUSION

Serum IL-6 was associated with an increase of energy expenditure in haemodialysis patients.

The impact of traditional and non-traditional risk factors on coronary calcification in pre-dialysis patients

BACKGROUND

Coronary heart disease (CHD) is the leading cause of death among end-stage renal disease patients. There is evidence that coronary calcification is a marker of atherosclerotic vascular disease and is predictive of cardiovascular events, especially in patients on renal replacement therapy. It has recently been suggested that CHD begins in the pre-dialysis period. However, data regarding coronary calcification in this population is scarce. This study was aimed at evaluating such coronary calcification and identifying related factors.

METHODS

A total of 96 chronic kidney disease out-patients who were not on dialysis were included. Patients presenting neoplastic, infectious or inflammatory diseases were excluded. Demographic characteristics, clinical profiles, laboratory test results and multislice computed tomography scans were evaluated.

RESULTS

The median age was 55 years (range 20-69 years), 67% were men and the median creatinine clearance was 37 ml/min/1.73 m(2). Coronary calcification, defined as a coronary artery calcification score (CACS) >0 Agatston units (AU), was seen in 61 patients (median 89.1 AU, range 0.37-2299.3 AU). On average, these patients were older, more often had diabetes, higher body mass indices and higher Framingham risk indices, as well as presenting higher proteinuria, intact parathyroid hormone (iPTH), blood glucose and triglyceride levels compared with those without calcification. Multiple logistic regression analysis, adjusted for age and diabetes, identified iPTH and triglyceride levels as independent determinants of calcification. Severe calcification (CACS >400 AU) was seen in 22 patients, who were also older and more frequently had a history of cardiovascular disease (CVD), as well as having higher levels of phosphorus, blood glucose and soluble Fas (sFas). Multiple logistic regression analysis, adjusted for age and diabetes, identified phosphorus and sFas levels as independent determinants of severe coronary calcification.

CONCLUSION

Coronary calcification is highly prevalent in pre-dialysis patients and correlates with traditional and non-traditional risk factors for CVD.

Characterization of glycosaminoglycans in tubular epithelial cells: calcium oxalate and oxalate ions effects

BACKGROUND

The interaction between tubular epithelial cells and calcium oxalate crystals or oxalate ions is a very precarious event in the lithogenesis. Urine contains ions, glycoproteins and glycosaminoglycans that inhibit the crystallization process and may protect the kidney against lithogenesis. We examined the effect of oxalate ions and calcium oxalate crystals upon the synthesis of glycosaminoglycans in distal [Madin-Darby canine kidney (MDCK)] and proximal (LLC-PK1) tubular cell lines.

METHODS

Glycosaminoglycan synthesis was analyzed by metabolic labeling with (35)S-sulfate and enzymatic digestion with specific mucopolysaccharidases. Cell death was assessed by fluorescent dyes and crystal endocytosis was analised by flow cytometry.

RESULTS

The main glycosaminoglycans synthesized by both cells were chondroitin sulfate and heparan sulfate most of them secreted to the culture medium or present at cellular surface. Exposition of MDCK cells to oxalate ions increased apoptosis rate and the incorporation of (35)S-sulfate in chondroitin sulfate and heparan sulfate, while calcium oxalate crystals were endocyted by LLC-PK1, induced necrotic cell death, and increased (35)S-sulfate incorporation in glycosaminoglycans. These effects seem to be specific and due to increased biosynthesis, since hydroxyapatite and other carboxylic acid did not induced cellular death or glycosaminoglycan synthesis and no changes in sulfation degree or molecular weight of glycosaminoglycans could be detected. Thapsigargin inhibited the glycosaminoglycan synthesis induced by calcium oxalate in LLC-PK1, suggesting that this effect was sensitive to the increase in cytosolic calcium.

CONCLUSION

Tubular cells may increase the synthesis of glycosaminoglycans to protect from the toxic insult of calcium oxalate crystals and oxalate ions, what could partially limit the lithogenesis.

Effects of customized bicarbonate buffered solutions for continuous renal replacement therapies on polymorphonuclear leukocytes function and viability

It has previously been shown that the mixture of bicarbonate and calcium in the solutions used for continuous renal replacement therapy led to crystallization and significant changes in calcium concentration and pH. The aim of this study was to investigate the impact of bicarbonate/calcium and lactate/calcium solutions for Continuous Renal Replacement Therapies (CRRT) on the viability and function of polymorphonuclear cells (PMN). We tested four customized bicarbonate buffered solutions: single bag (bicarbonate and calcium mixed 24 h before testing), double bag (mixed immediately before testing), filtered single bag and double bag solutions, and a commercial lactate buffered solution. Blood from 6 volunteers was incubated with the solutions for 30 min followed by PMN isolation. After overnight incubation, viability, phagocytosis, and peroxide production by PMN were determined by flow cytometry. There was no difference between the test solutions with respect to PMN viability and function. Therefore, the presence of microcrystals and the consequent changes in electrolyte concentrations do not seem to impair PMN function.

Customized bicarbonate buffered dialysate and replacement solutions for continuous renal replacement therapies: effect of crystallization on the measured levels of electrolytes and buffer

The aim of this study was to investigate the impact of the addition of calcium to bicarbonate solutions for continuous renal replacement therapy (CRRT). We tested single bag (bicarbonate and calcium mixed 24 h before testing) and double bag solutions (mixed immediately before) with and without the addition of 4 mEq/L of acetate. Prescribed calcium varied from 0 to 5 mEq/L. All test solutions containing calcium showed crystallization at light microscopy. The double bag solutions decreased but did not prevent crystallization. The addition of acetate did not interfere with crystallization. Crystallization, as measured by the weight of the crystals after filtration of the solutions, showed a significant positive correlation with the calcium deficit (prescribed minus measured) and with partial pressure of carbon dioxide. The measured level of calcium was lower than expected and correlated with crystallization. Our results suggest that the use of bicarbonate solutions containing calcium as replacement fluids for CRRT is a potentially unsafe procedure.

[Prevalence of cryptosporidiosis in diarrheic syndrome in HIV positive patients]

During the period February 1987-June 1988, we examined 542 stool samples of 271 HIV positive patients both with and without full-blown AIDS. One hundred patients with either acute or chronic diarrhea and 180 patients without diarrhea were studied. The stool samples were examined for the presence of Cryptosporidium sp., other protozoa, helmints, and pathogenic enterobacteria. We found a prevalence of 14.3% of Cryptosporidium sp. in patients with full-blown disease and diarrhea. We encountered no Cryptosporidium sp. among asymptomatic patients. The occurrence of diarrhea was significantly associated with a CD4/CD8 ratio lower than 0.4, with the finding of Cryptosporidium sp. in the stools, being a CDC group IV, and with a positive stool culture for pathogenic enterobacteria. The diarrhea caused by Cryptosporidium sp. could not be distinguished, on clinical grounds, from diarrhea caused by other etiologic agents.

Comparison of daily and twice-weekly regimens to treat pulmonary tuberculosis

A randomised controlled trial compared the effectiveness and toxicity in pulmonary tuberculosis of two drug regimens containing rifampicin and isoniazid given daily or twice-weekly for 4 months after a 2-month period of intensive treatment with daily isoniazid, rifampicin, and pyrazinamide. 667 patients with newly diagnosed pulmonary tuberculosis were randomly allocated to continue daily treatment with isoniazid (400 mg) and rifampicin (600 mg) or to twice-weekly treatment with isoniazid (900 mg) and rifampicin (600 mg). 544 of the 667 patients (81%) completed the 6-month course (287 of 337 [85%] treated daily and 257 of 330 [79%] treated twice-weekly). Drug toxicity was not a great problem; the treatment was permanently discontinued in only 2% of patients. There was no significant difference at the end of months 5 and/or 6 of chemotherapy between the groups treated daily and twice-weekly in the proportions with bacteriological failure (at least one positive sputum culture with more than 20 colonies) or who had died from tuberculosis (17 [6%] vs 10 [3%]). Nor was there a significant difference in the relapse rate (17 [7%] treated daily vs 10 [4%] treated twice-weekly) during follow-up of 12 months. Thus, the twice-weekly regimen was at least as effective as the daily regimen for treatment of pulmonary tuberculosis.