Adsorption and Thermal Reactions of Alkanethiols on Pt(111): Dependence on the Length of the Alkyl Chain

The adsorption and thermal decomposition of alkanethiols (R-SH, where R = CH3, C2H5, and C4H9) on Pt(111) were studied with temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) with synchrotron radiation. Dissociation of sulfhydryl hydrogen (RS-H) of alkanethiol results in the formation of alkanethiolate; the extent of dissociation at an adsorption temperature of 110 K depends on the length of the alkyl chain. At small exposure, all chemisorbed CH3SH, C2H5SH, and C4H9SH decompose to desorb hydrogen below 370 K and yield carbon and sulfur on the surface. Desorption of products containing carbon is observed only at large exposure. In thermal decomposition, alkanethiolate is proposed to undergo a stepwise dehydrogenation: R'-CH2S --> R'-CHS --> R'-CS, R' = H, CH3, and C3H7. Further decomposition of the R'-CS intermediate results in desorption of H2 at 400-500 K and leaves carbon and sulfur on the surface. On the basis of TPD and XPS data, we conclude that the density of adsorption of alkanethiol decreases with increasing length of the alkyl chain. C4H9SH is proposed to adsorb mainly with a configuration in which its alkyl group interacts with the surface; this interaction diminishes the density of adsorption of alkanethiols but facilitates dehydrogenation of the alkyl group.

Thiamine deficiency and unexplained encephalopathy in hemodialysis and peritoneal dialysis patients

Patients with end-stage renal disease undergoing regular dialysis are prone to encephalopathy, but the cause is often unclear. Dialysis patients are at risk for thiamine deficiency, which may mimic many uremic complications, including encephalopathy. To determine whether unexplained encephalopathy in regular dialysis patients is associated with thiamine deficiency, we conducted a prospective study that enrolled 30 consecutive dialysis patients with altered mental status admitted to a referred hospital during a 1-year period. A complete history, physical and neurological examinations, laboratory investigations, and computed tomographic scans or magnetic resonance imaging of the brain were obtained for each subject. In 10 of the 30 patients, diagnoses remained obscure after the initial workup. Manifestations included confusion, chorea, acute visual loss, rapidly progressive dementia, myoclonus, convulsions, and coma. Intravenous thiamine was administered to these 10 patients. All 10 patients had thiamine deficiency confirmed by a marked response to thiamine supplementation and/or a low serum thiamine concentration (35.3 +/- 6.0 nmol/L; normal, >50 nmol/L). Nine patients recovered, but one patient failed to respond because of delayed treatment. We conclude that in regular dialysis patients, unexplained encephalopathy can be mainly attributed to thiamine deficiency. This condition is fatal if unrecognized and can be successfully treated with prompt thiamine replacement.

Erythropoietin and iron: the role of ascorbic acid

Provision of sufficient available iron is a prerequisite to ensure the optimal response to recombinant human erythropoietin (rHuEpo). Functional iron deficiency (a state when iron supply is reduced to meet the demands for increased erythropoiesis) is the common cause of rHuEpo hyporesponsiveness in dialysis patients who have normal iron status, even when they are iron-overloaded. Iron supplementation is not justified for this hyporesponsiveness in patients with iron overload due to the potential hazards of iron overload aggravated by intravenous iron therapy. Furthermore, in vivo studies indicated that the promising effect of intravenous iron medication to overcome iron-deficient erythropoiesis is not observed in iron-overloaded haemodialysis (HD) patients. Ascorbic acid, a water-soluble antioxidant as well as a reducing agent, has a number of associations with iron metabolism. Recent research highlights that ascorbic acid can potentiate the mobilization of iron from inert tissue stores and facilitates the incorporation of iron into protoporphyrin in iron-overloaded HD patients being treated with rHuEpo. Interest has turned towards the use of ascorbic acid as an adjuvant therapy in this field. This review focuses on the improvement of rHuEpo response by administration of ascorbic acid and discusses its clinical implications and potential issues for nephrologists.

An occult cause of arteriovenous access failure: central vein stenosis from permanent pacemaker wire. Report of three cases and review of the literature

Central vein stenosis is an indolent and underestimated complication of permanent pacemaker placement. It leads to serious problems in hemodialysis patients when arteriovenous (AV) fistulae/grafts were created at the ipsilateral arm. We, herein, reported 3 cases of AV access failure resulting from permanent pacemaker-related central vein stenosis. The pathogenesis, clinical manifestations, radiological findings, and therapeutic solution on this issue are discussed. It is mandatory to place the AV fistula/graft and permanent pacemaker wire on the opposite side for prevention of the high risk of AV access failure.

Chorea induced by thiamine deficiency in hemodialysis patients

Thiamine deficiency is mainly encountered in alcoholics or food faddists, but it may complicate chronic dialysis because of low intake and accelerated loss of thiamine in dialysis patients. We report here 2 hemodialysis (HD) patients who developed chorea induced by thiamine deficiency. We propose that thiamine deficiency, with a consequent dysfunction of the basal ganglia, may induce chorea in HD patients.

8-hydroxy-2'-deoxyguanosine of leukocyte DNA as a marker of oxidative stress in chronic hemodialysis patients

In contrast to proteins and lipids, oxidative damage to DNA has not been well studied in patients undergoing hemodialysis (HD). We hypothesized that phagocytes are activated after blood-membrane contact during HD, and oxidants from metabolic activation can damage leukocyte DNA. To test this hypothesis, the 8-hydroxy-2'-deoxyguanosine (8-OHdG) content of leukocyte DNA was measured by high-performance liquid chromatography electrochemical detection method in 35 age- and sex-matched healthy subjects, 22 undialyzed patients with advanced renal failure, and 109 HD patients to assess the relation between oxidative DNA damage and complement-activating membranes, blood antioxidants, and iron status. Dialysis membranes were classified into complement-activating (cellulose; n = 55) and non-complement-activating (polymethylmethacrylate [PMMA]; n = 35; polysulfone [PS]; n = 19) membranes. We found increased oxidative stress in undialyzed and HD patients based on a decrease in plasma levels of ascorbate and alpha-tocopherol adjusted for blood lipid (alpha-tocopherol/lipid), serum albumin, and reduced glutathione levels in whole blood and an increase in oxidized glutathione levels in whole blood compared with controls (P < 0.001). The greatest 8-OHdG level in leukocyte DNA was in HD patients, followed by undialyzed patients and healthy controls (P < 0.001), and was significantly greater in HD patients using cellulose membranes than those using PMMA or PS membranes (P < 0.001). 8-OHdG levels correlated with plasma alpha-tocopherol/lipid (r = -0.314; P < 0.005), serum iron (r = 0. 446; P < 0.001), and transferrin saturation values (r = 0.202; P < 0.05) in the analysis of all HD patients. In a 6-week crossover study, 8-OHdG levels significantly decreased after the switch from cellulose to synthetic membranes for 2 weeks and increased after the shift from synthetic to cellulose membranes (P < 0.05). Iron metabolism indices and plasma alpha-tocopherol/lipid values did not change significantly in the study period. We conclude that 8-OHdG content in leukocyte DNA is a biomarker of oxidant-induced DNA damage in HD patients. Oxidative DNA damage is a consequence of uremia, further augmented by complement-activating membranes.

Spiral computed tomographic angiography--a new technique for evaluation of vascular access in hemodialysis patients

Spiral computed tomographic angiography (CTA), a new noninvasive imaging technique, was used to study 10 arteriovenous fistulas (AVF) in 9 hemodialysis patients. Digital subtraction angiography (DSA) was also performed as a gold standard for comparison. AVF stenosis was graded by a four-point scale: grade 0, well patency of supplying artery, anastomosis and drainage vein; grade 1, < 50% stenosis; grade 2, 50-70% stenosis; grade 3, 70-99% stenosis, and grade 4, total occlusion. We found CTA correlated closely to DSA in detecting both stenosis and dilatation of AVF and it spared all the shortcomings of DSA. CTA has the potential to be alternative for imaging of dialysis fistulas. Further studies will be performed to specify the role of CTA images in the assessment of the hemodialysis vascular access.

Ultrasound-guided cannulation of the internal jugular vein for dialysis vascular access in uremic patients

BACKGROUND

A reliable temporary vascular access is always required for hemodialysis when a permanent vascular access is not available. However, techniques for creating temporary vascular accesses remain imperfect. This study utilized the 'SiteRite' ultrasound device to improve both success and complication rates of jugular venous cannulation for temporary access.

METHODS

This prospective, comparative study recruited 104 uremic patients receiving ultrasound-guided and 86 patients undergoing landmark-guided percutaneous internal jugular venous cannulation of dual-lumen dialysis catheters. Success rate, number of puncture attempts, access time, and the complication rate of the ultrasound technique, in comparison with the landmark-guided technique, were studied.

RESULTS

The ultrasound-guided cannulation was superior to the external landmark-guided cannulation in overall success rate (99.0 vs. 86.0%, p < 0.01), success rate of the first puncture attempt (80.8 vs. 34.9%, p < 0.01), average puncture (access) times (15.8 vs. 43.7 s, p < 0.01), puncture trials (1.39 vs. 2.58, p < 0.01), and traumatic complication rate (1.9 vs. 1 1.6%, p = 0.015). The incidence of infective complications for the ultrasound group was not different from that of the landmark-guided groups (2.9 vs. 2.3%, p = 0.589).

CONCLUSION

The ultrasound-guided technique offers both safety and convenience in inserting jugular venous dialysis catheters. It represents a valuable technique in creating temporary dialysis hemoaccesses.

Improvement of nutritional status in patients receiving maintenance hemodialysis after correction of renal anemia with recombinant human erythropoietin

Despite a large body of evidence showing the beneficial effects of successful treatment of anemia with recombinant human erythropoietin (EPO) in patients with end-stage renal disease, controversy remains as to whether EPO treatment of anemia can improve the nutritional status in patients on maintenance hemodialysis. This prompted us to conduct a prospective study in 41 hemodialysis patients with basal hemoglobin less than 9 g/dl. The dose of EPO was increased for 12 weeks to achieve the target hemoglobin concentration of 10 g/dl and then titrated in the following 12 weeks to maintain the target value. Nutritional status was assessed at baseline and after 6 months of follow-up, using the global protein-calorie malnutrition (PCM) index proposed by Bilbrey and Cohen. A low global PCM score indicates better nutrition. The results showed that hemoglobin values significantly increased from 8.7 +/- 0.8 g/dl at baseline to 10.7 +/- 0.5 g/dl in the 6th month (p < 0.001). No significant changes were observed in the normalized protein catabolic rate and Kt/V during the study period. Global PCM scores improved from 30.0 +/- 7.5 to 23.6 +/- 3.1 (p < 0.001) and paralleled the correction of anemia by EPO treatment. The data were consistent with a major improvement in the nutritional markers of relative body weight, triceps skinfold, midarm circumference, midarm muscle circumference, serum albumin, serum transferrin and total lymphocyte count in the 6th month as compared to baseline. The percentages of mild and moderate-severe PCM at baseline were 32 and 58%, respectively. These percentages were significantly reduced during the 6th month to 20 and 30%, respectively (p = 0.0004). In summary, correction of renal anemia with EPO improves the nutritional status in hemodialysis patients. A postulated mechanism is that EPO may exhibit anabolic effects, with a better utilization of ingested protein.

Recombinant human erythropoietin resistance in iron-replete hemodialysis patients: role of aluminum toxicity

The present study was designed to investigate the impact of aluminum toxicity on the response to recombinant human erythropoietin (rHuEPO) therapy in hemodialysis patients, when iron deficiency has been corrected or excluded. We studied 39 patients on regular hemodialysis (20 males and 19 females; mean age 58.8 years), who were under maintenance rHuEPO treatment for at least 6 months, and who had stable hematocrit levels for more than 3 months. All patients had adequate iron stores and availability with serum ferritin > 100 micrograms and iron saturation > 25%. They were classified into two groups: 19 poor responders, who required subcutaneous rHuEPO doses > 100 U/kg/week and failed to achieve the target hematocrit level of 30%, and 20 good responders, who needed doses of < or = 100 U/kg/week to maintain the target level. Serum aluminum levels including basal (Albasal) and 44 h after desferrioxamine (DFO) infusion (Alpost-DFO), intact parathyroid hormone, and inflammatory and hemolytic indices were examined in both groups. The results showed that the mean weekly rHuEPO doses were significantly lower and the mean hematocrit levels higher in the good responders than in the poor responders. Although the poor responders had markedly higher mean Albasal and Alpost-DFO levels, no differences were observed in the other parameters between the two groups. Furthermore, the poor responders significantly had the greater increment in the serum aluminum levels after DFO infusion (delta Al = Alpost-DFO-Albasal). The mean corpuscular volume had a strong inverse correlation with delta Al in the poor response group (r = -0.711, p < 0.001). We concluded that the post-DFO rise of serum aluminum can be used as a means of estimating tissue stores. Subclinical aluminum toxicity may exhibit an inhibitory effect on erythropoietic response to rHuEPO therapy.

Persistent transforming growth factor-beta 1 expression may predict peritoneal fibrosis in CAPD patients with frequent peritonitis occurrence

The efficiency of continuous ambulatory peritoneal dialysis depends on the permeability of the peritoneal membrane. Peritoneal fibrosis (PF) causes loss of the dialytic function. Several studies have indicated that PF is closely related to the proliferation of peritoneal fibroblasts and the deposition of extracellular matrix. Transforming growth factor-beta 1 (TGF-beta1) plays a major role in stimulating extracellular matrix deposition. Frequent peritonitis occurrence may cause persistent TGF-beta1 mRNA expression. In an attempt to search for a factor related to PF, we designed a longitudinal study to measure TGF-beta1 levels in dialysate and TGF-beta1 mRNA expression in peritoneal mononuclear cells from peritoneal dialysate before onset, once a week during peritonitis, and after peritonitis in high and low peritonitis occurrence (HPO and LPO) patients. Fifteen patients with a LPO rate and 5 patients with a HPO rate were followed up longitudinally. Meanwhile, TGF-beta1 levels and TGF-beta1 mRNA expression were augmented in peritoneal dialysate effluents before, during, and after the episodes of peritonitis. The peritoneal permeability was evaluated by the peritoneal equilibration test. The results revealed that in the LPO group, TGF-beta1 and TGF-beta1 mRNA were detectable at early stages of peritonitis, but the levels decreased rapidly and were undetectable 2 weeks after peritonitis. On the other hand, in the HPO group, TGF-beta1 and TGF-beta1 mRNA persisted for a long time. We could detect TGF-beta1 and TGF-beta1 mRNA in dialysate effluents and peritoneal mononuclear cells even 2, 3, and 4 weeks after episodes of peritonitis. When compared with that of first or second episode of peritonitis, the peritoneal function evaluated with the peritoneal equilibration test was found to obviously deteriorate during the third episode of peritonitis. These findings were confirmed by an in situ hybridization technique to evaluate the relationship between TGF-beta1 mRNA expression and PF from biopsied peritoneal specimens. These findings suggest that the high TGF-beta1 levels in the dialysate are related to an increased expression of TGF-beta1 in the peritoneum. Thus, the persistent TGF-beta1 expression in the peritoneum may serve as a useful parameter in predicting PF in continuous ambulatory peritoneal dialysis patients with frequent peritonitis occurrence.

Effect of vitamin E-bonded membrane on the 8-hydroxy 2'-deoxyguanosine level in leukocyte DNA of hemodialysis patients

BACKGROUND

8-Hydroxy 2'-deoxyguanosine (8-OHdG) of leukocyte DNA has been identified as a surrogate marker of oxidative stress in chronic hemodialysis (HD) patients. In this study, we focused on the determinants of the 8-OHdG level in leukocyte DNA of HD patients. We further investigated the influence of vitamin E-modified, regenerated cellulose (CL-E) membrane on the oxidative DNA damage, intracellular reactive oxygen species (ROS) production of granulocytes, and plasma alpha-tocopherol concentration.

METHODS

8-OHdG content in cellular DNA of leukocytes was measured by a high-performance liquid chromatography-electrochemical detection (HPLC-ECD) method. Intracellular production of ROS, H2O2 and O2-. were analyzed by flow cytometry in leukocytes with and without phorbol-12-myristate-13-acetate (PMA) stimulation before dialysis, as well as at 15 and 30 minutes of dialysis. Plasma alpha-tocopherol concentration was measured by a HPLC method, and the value of alpha-tocopherol was corrected by total blood lipid concentration.

RESULTS

In the prospective cross sectional study, the mean 8-OHdG level in leukocyte DNA was equally lower in the patients of the CL-E, polymethylmethacrylate (PMMA), and polysulfone (PS) groups as compared with the cellulosic group (ANOVA, P < 0.001). The leukocyte 8-OHdG level correlated negatively with plasma alpha-tocopherol and blood lipid-adjusted plasma alpha-tocopherol, but correlated positively with serum iron and percentage of transferrin saturation. Forward stepwise multiple regression showed that dialysis membrane type, serum iron, and blood lipid-adjusted plasma alpha-tocopherol were the independent determinants of the leukocyte 8-OHdG level in HD patients. Like synthetic membranes, granulocyte ROS production was less augmented during dialysis with the CL-E membrane as compared with the cellulose membrane. Exposure to cellulose membrane impaired intracellular ROS production of granulocytes in response to PMA challenge, whereas the CL-E and synthetic membranes improved the granulocyte responsiveness to PMA. In the longitudinal cross-over study, the 8-OHdG level significantly decreased, and blood lipid-adjusted plasma alpha-tocopherol increased after switching the cellulose membrane to CL-E or synthetic membrane for eight weeks. In contrast, the 8-OHdG level dramatically rose, and blood lipid-adjusted plasma alpha-tocopherol declined after shift of CL-E or synthetic membrane to the cellulose membrane.

CONCLUSIONS

CL-E membrane exhibited biocompatible and bioactive characteristics. Like synthetic membranes, treatment with a CL-E dialyzer effectively reduced the 8-OHdG content in leukocyte DNA, suppressed intracellular ROS production of granulocytes, and preserved the plasma level of vitamin E. It could further improve granulocyte responsiveness to a PMA challenge. Reduced DNA damage and improved immune function of leukocytes may reduce the cancer and infection risks in chronic HD patients.

Significance of nitrogen removal mass in uremic patients on different modalities of dialysis therapy

BACKGROUND AND PURPOSE

While most nephrologists use Kt/V values for dialysis prescriptions, some researchers are beginning to view the role of solute removal mass as an indicator of adequate dialysis. This study, using nitrogen as a surrogate for solute removal, probed whether solute removal mass can be used as the target of adequate dialysis. Mathematical formulas for easy bedside calculation of nitrogen removal mass were used to avoid the problems associated with direct measurement.

METHODS

The weekly removal mass of urea nitrogen (M) and the urea generation rate (G) of 32 conventional hemodialysis (HD) and 21 continuous ambulatory peritoneal dialysis (CAPD) patients were calculated. All the patients were anuric, clinically stable, and under adequate dialysis pursuant to either the criterion of the urea index, Kt/V, or clinical requirements.

RESULTS

The difference in MHD (MHD = 41.9 +/- 9.5 g/week, MCAPD = 38.8 +/- 11.9 g/week) and G (GHD = 3.90 +/- 1.02 mg/min, GCAPD = 3.85 +/- 1.21 mg/min) between the two groups was statistically insignificant (p = 0.119 and p = 0.868, respectively). When protein nitrogen leaking through the peritoneal membrane was considered and added to MCAPD, nitrogen removal in CAPD patients (M'CAPD = 42.3 +/- 13.0 g/week) approached that in HD patients (p = 0.886). There was no correlation between dialysis dosage and urea removal mass in either the CAPD or HD groups.

CONCLUSIONS

Urea nitrogen removal mass is similar to the protein catabolic rate (PCR) in stable patients. It is meaningful in dialysis evaluation only when it is used simultaneously with blood urea nitrogen measurement. However, because M changes at the inception of dialysis, it more significant than PCR in the evaluation of unstable patients.

Glomerular epithelial-myofibroblast transdifferentiation in the evolution of glomerular crescent formation

BACKGROUND

Glomerular cellular crescents consist of epithelial cells and macrophages, which can undergo an irreversible process of fibrous organization. However, the origin of the fibroblast-type cells that mediate this fibrous organization is unclear.

METHODS

This study examined glomerular epithelial- myofibroblast transdifferentiation (GEMT) in the formation and evolution of glomerular crescents in two distinct rat models of glomerulonephritis: 5/6 nephrectomy and antiglomerular basement membrane (GBM) disease.

RESULTS

Early in the course of both disease models, and prior to crescent formation, immunohistochemistry staining and in-situ hybridization demonstrated de novo expression of alpha-smooth-muscle actin (alpha-SMA), a marker of smooth muscle cells and myofibroblasts, by glomerular parietal epithelial cells (GPEC). The expression of alpha-SMA by GPEC was accompanied by a loss of E-cadherin staining, a marker of epithelial cells. At this early stage of GEMT, ultrastructural studies identified the presence of characteristic actin microfilaments and dense bodies within GPEC which retained a normal epithelial morphology with apical-basal polarity and microvilli. A late stage of transdifferentiation was seen in fibrocellular crescents. In this case, GPEC attached to intact segments of the capsular basement membrane contained large bundles of actin microfilaments throughout the cell, and this was accompanied by a loss of polarity, microvilli, and tight junctions. There was a significant correlation between the presence of alpha-SMA(+) GPEC and glomerular crescent formation. Cellular crescents contained small numbers of alpha-SMA(+) myofibroblasts. These cells become the dominant population in fibrocellular crescents, which was associated with marked local proliferation. Relatively few alpha-SMA(+) myofibroblasts remained in fibrotic/organizing crescents. Most cells within cellular and fibrocellular crescents expressed transforming growth factor-beta (TGF-beta) and basic fibroblast growth factor (FGF-2), suggesting that these growth factors may regulate this GEMT process during the evolution of glomerular crescents.

CONCLUSIONS

This study provides the first phenotypic and morphological evidence that glomerular epithelial-myofibroblast transdifferentiation participates in the formation and evolution of glomerular crescents.

Intravenous ascorbic acid as an adjuvant therapy for recombinant erythropoietin in hemodialysis patients with hyperferritinemia

BACKGROUND

Inadequate iron mobilization and defective iron utilization may cause recombinant erythropoietin (rEPO) hyporesponsiveness in hemodialysis (HD) patients with iron overload. We have demonstrated that intravenous ascorbic acid (IVAA), but not intravenous iron medication, can effectively circumvent the functional iron-deficient erythropoiesis associated with iron overload in HD patients. However, it is uncertain whether all HD patients with hyperferritinemia will consistently respond to IVAA and which index may indicate functional iron deficiency in the special entity. Therefore, a prospective study was conducted to establish the guidelines for IVAA adjuvant therapy.

METHODS

Sixty-five HD patients with serum ferritin levels of more than 500 microgram/liter were recruited and divided into the control (N = 19) and IVAA (N = 46) groups. IVAA patients with a hematocrit (Hct) of less than 30% received 300 mg of ascorbic acid three times per week for eight weeks. Controls had a Hct of more than 30% and did not receive the adjuvant therapy. Red blood cell and reticulocyte counts, iron metabolism indices, erythrocyte zinc protoporphyrin (E-ZPP), and the concentrations of plasma ascorbate and oxalate were examined before and following the therapy.

RESULTS

Thirteen patients (four controls and nine IVAA patients) withdrew by the end of the study. Eighteen patients had a dramatic response to IVAA with a significant increase in their hemoglobin and reticulocyte index and a concomitant 24% reduction in rEPO dose after eight weeks. This paralleled a significant rise in serum iron and transferrin saturation (TS) and a fall in E-ZPP and serum ferritin (baselines vs. 8 weeks, serum iron 68 +/- 37 vs. 124 +/- 64 microgram/dl, TS 27 +/- 10 vs. 48 +/- 19%, E-ZPP 123 +/- 44 vs. 70 +/- 13 micromol/mol heme, and serum ferritin 816 +/- 435 vs. 587 +/- 323 microgram/liter, P < 0. 05). Compared with responders, mean values of hemoglobin, rEPO dose, iron metabolism parameters, and E-ZPP showed no significant changes in controls (N = 15) and in non-responders (N = 19). Thirty-seven patients (18 responders and 19 non-responders) were further analyzed by receiver operating characteristic curves to seek the criteria for prediction of a response to IVAA treatment. The results showed that E-ZPP at a cut-off level of more than 105 micromol/mol heme and TS at a level of less than 25% were more specific to confirm the status of functional iron deficiency in iron-overloaded patients. The two criterion values had the highest accuracy to predict a response to treatment.

CONCLUSIONS

Functional iron-deficient erythropoiesis plays a role in rEPO-hyporesponsive anemia in HD patients with hyperferritinemia. IVAA may be an adjuvant therapy for rEPO in these patients, and E-ZPP of more than 105 micromol/mol heme and TS of less than 25% should be used to guide the IVAA treatment.

Activation of Kupffer cells and caspase-3 involved in rat hepatocyte apoptosis induced by endotoxin

BACKGROUND/AIMS

Sepsis and lipopolysaccharides (LPS) cause mild to severe hepatic dysfunction. In this study, Kupffer cell activation, involvement of TNFalpha and caspases downstream of the TNFalpha receptor were examined in hepatocyte apoptosis induced by LPS.

METHODS

In in vivo experiments, male Sprague-Dawley rats were injected intravenously with LPS, and small amounts of the blood and liver were sampled to evaluate apoptosis. Kupffer cells were inactivated by pretreatment with gadolinium chloride for 2 days. In in vitro experiments, hepatocytes and Kupffer cells were separately isolated from rat livers using collagenase perfusion.

RESULTS

LPS induced time-dependent and dose-dependent increases in the number of TUNEL-positive cells, which coincided with the apoptotic features of hepatocytes demonstrated by electron microscopy and DNA ladder. Activation of caspase-3-like proteases was observed with an increase in the number of apoptotic hepatocytes. Immunostaining with activated caspase-3-specific antibody showed that caspase-3 was activated only in the cytoplasm of TUNEL-positive hepatocytes. Inactivation of Kupffer cells by gadolinium chloride was concomitantly accompanied by the prevention of caspase-3 activation, hepatocyte apoptosis and liver injury induced by LPS. The co-culture system of hepatocytes and Kupffer cells, but neither cell culture system, individually, showed LPS-induced hepatocyte apoptosis. Kupffer cell-conditioned medium induced hepatocyte apoptosis, whereas addition of anti-TNFalpha antibody to Kupffer cell-conditioned medium did not. Additions of acetyl-DEVD-CHO, acetyl-YVAD-CHO, and acetyl-IETD-CHO to Kupffer cell-conditioned medium decreased the number of apoptotic hepatocytes.

CONCLUSIONS

These results suggest that the activation of Kupffer cells, TNFalpha and caspases downstream of TNFR1 were involved in hepatocyte apoptosis induced by LPS.

Activation of Kupffer cells and caspase-3 involved in rat hepatocyte apoptosis induced by endotoxin

BACKGROUND/AIMS

Sepsis and lipopolysaccharides (LPS) cause mild to severe hepatic dysfunction. In this study, Kupffer cell activation, involvement of TNFalpha and caspases downstream of the TNFalpha receptor were examined in hepatocyte apoptosis induced by LPS.

METHODS

In in vivo experiments, male Sprague-Dawley rats were injected intravenously with LPS, and small amounts of the blood and liver were sampled to evaluate apoptosis. Kupffer cells were inactivated by pretreatment with gadolinium chloride for 2 days. In in vitro experiments, hepatocytes and Kupffer cells were separately isolated from rat livers using collagenase perfusion.

RESULTS

LPS induced time-dependent and dose-dependent increases in the number of TUNEL-positive cells, which coincided with the apoptotic features of hepatocytes demonstrated by electron microscopy and DNA ladder. Activation of caspase-3-like proteases was observed with an increase in the number of apoptotic hepatocytes. Immunostaining with activated caspase-3-specific antibody showed that caspase-3 was activated only in the cytoplasm of TUNEL-positive hepatocytes. Inactivation of Kupffer cells by gadolinium chloride was concomitantly accompanied by the prevention of caspase-3 activation, hepatocyte apoptosis and liver injury induced by LPS. The co-culture system of hepatocytes and Kupffer cells, but neither cell culture system, individually, showed LPS-induced hepatocyte apoptosis. Kupffer cell-conditioned medium induced hepatocyte apoptosis, whereas addition of anti-TNFalpha antibody to Kupffer cell-conditioned medium did not. Additions of acetyl-DEVD-CHO, acetyl-YVAD-CHO, and acetyl-IETD-CHO to Kupffer cell-conditioned medium decreased the number of apoptotic hepatocytes.

CONCLUSIONS

These results suggest that the activation of Kupffer cells, TNFalpha and caspases downstream of TNFR1 were involved in hepatocyte apoptosis induced by LPS.

Erythropoietin hyporesponsiveness: from iron deficiency to iron overload

Iron deficiency is the most frequently encountered cause of suboptimal response to recombinant human erythropoietin (rHuEPO). Carefully assessing iron status is of paramount importance in chronic renal failure patients prior to or during rHuEPO therapy. Because there is great need for iron in the EPO-stimulated erythroid progenitors, it is essential that serum ferritin and transferrin saturation levels should be maintained over 300 microg/liter and 30%, respectively. Investigators have shown that oral iron is unlikely to keep pace with the iron demand for an optimal rHuEPO response in uremics. Therefore, patients with iron deficiency will always require intravenous iron therapy. The early and prompt iron supplementation can lead to reductions in rHuEPO dose and hence cost. After the iron deficiency has been corrected or excluded, we must remember all of the possible causes of hyporesponsiveness in every rHuEPO-treated patient. As dose requirements vary, it is not clear which dose of rHuEPO causes this hyporesponsiveness. However, if the patient with iron repletion does not respond well after the induction period, the major causes blunting the response to rHuEPO should be investigated. Most factors are reversible and remediable, except resistant anemia associated with hemoglobinopathy or bone marrow fibrosis, which requires a further increase in the rHuEPO dose. By means of early detection and correction of the possible causes, the goal of increasing therapeutic efficacy can be achieved. Iron overload may lead to an enhanced risk for infection, cardiovascular complication, and cancer. Over-treatment with iron should be avoided in dialysis patients, despite the fact that the safe upper limit of serum ferritin to avoid iron overload is not clearly defined. On the other hand, functional iron deficiency may develop even when serum ferritin levels are increased. Controversy remains as to whether intravenous iron therapy can overcome this form of hyporesponsiveness in iron-overloaded patients. Moreover, a treatment option of iron supplementation is not warranted in these patients, as the potential hazards of iron overload will be worsened. We demonstrated that the mean hematocrit significantly increased from 25.1+/-0.9% to 31+/-1.2% after eight weeks of intravenous ascorbate therapy (300 mg three times a week) in 12 hemodialysis patients with serum ferritin levels of more than 500 microg/liter. The enhanced erythropoiesis paralleled with a rise in transferrin saturation (27.8+/-2.5% vs. 44.8+/-9.5%, P < 0.05) and reductions in erythrocyte zinc protoporphyrin (130+/-32 vs. 72+/-19 micromol/mol heme, P < 0.05) and monthly rHuEPO dose (24.2+/-4.5 vs. 16.8+/-3.4 x 10(3) units, P < 0.05) at the end of study. It is speculated that ascorbate supplementation not only facilitates the iron release from storage sites and its delivery to hematopoietic tissues, but also increases iron utilization in erythroid cells. Our study provides a more complete understanding of the pathogenesis of iron overload-related anemia and the development of an adjuvant therapy, intravenous ascorbic acid, to the existing treatments.

Internal jugular vein haemodialysis catheter-induced right atrium endocarditis--case report and review of the literature

We present a case of right-sided endocarditis as a life-threatening complication of having a jugular vein haemodialysis catheter inadvertently placed in the right atrium. The mechanisms of direct traumatization of the endocardium by the catheter tip and continuous inoculation of bacteria onto the endocardial surface make dual lumen catheter-induced endocarditis similar to the pathophysiology of experimental endocarditis in animals. Therefore, the catheter tip should be placed in the distal superior vena cava during cannulation. Once endocarditis is present, removal of catheters and a 4-6-week course of intravenous antibiotics guided by the sensitivity test are recommended.

A parallel, comparative study of intravenous iron versus intravenous ascorbic acid for erythropoietin-hyporesponsive anaemia in haemodialysis patients with iron overload

BACKGROUND

Functional iron deficiency may develop and cause erythropoietin resistance in haemodialysis patients with iron overload. Controversy remains as to whether intravenous iron medication can improve this hyporesponsiveness due to decreased iron availability, or whether iron therapy will aggravate haemosiderosis. Intravenous administration of ascorbic acid has been shown to effectively circumvent resistant anaemia associated with iron overload in a small preliminary study. To elucidate further the possible mechanisms of this resistance, a parallel, comparative study was conducted to compare the effects of intravenous iron and ascorbate therapies in iron-overloaded haemodialysis patients.

METHODS

Fifty haemodialysis patients with serum ferritin of > 500 microg/l were randomly divided into two protocols. They were further stratified into controls (Control I, n = 11) and intravenous iron group (IVFE, n = 15) in protocol I; and into controls (Control II, n = 12) and intravenous ascorbic acid group (IVAA, n = 12) in protocol II. Controls had a haematocrit of > 30% and did not receive any adjuvant therapy. IVFE and IVAA patients were hyporesponsive to erythropoietin and functionally iron deficient. Ferric saccharate (100 mg dose) was administered intravenously postdialysis on five consecutive dialysis sessions in the first 2 weeks; and ascorbic acid (300 mg dose) thrice a week for 8 weeks. Red cell and iron metabolism indices were examined before and following therapy.

RESULTS

Mean values of haematocrit and transferrin saturation were significantly lower, and erythropoietin dose was higher in IVFE and IVAA patients compared to controls. Intravenous iron therapy neither improved erythropoiesis nor reduced erythropoietin dose during 12 weeks. Iron metabolism indices significantly increased at 2 and 6 weeks, but decreased at 12 weeks returning to the baselines. In contrast, mean haematocrit significantly increased from 25.8+/-0.5 to 30.6+/-0.6% with a concomitant reduction of 20% in erythropoietin dose after 8 weeks of ascorbate therapy. Serum ferritin modestly fell but with no statistical significance. The enhanced erythropoiesis paralleled a rise in transferrin saturation from 27+/-3 to 48+/-6% and serum iron from 70+/-11 to 107+/-19 microg/dl (P<0.05).

CONCLUSIONS

Short term intravenous iron therapy cannot resolve the issue of functional iron deficiency in haemodialysis patients with iron overload. Intravenous administration of ascorbic acid not only facilitates iron release from storage sites, but also increases iron utilization in the erythron. Our study draws attention to a potential adjuvant therapy, intravenous ascorbic acid, to treat erythropoietin-hyporesponsive anaemia in iron-overloaded patients.

Tubular epithelial-myofibroblast transdifferentiation in progressive tubulointerstitial fibrosis in 5/6 nephrectomized rats

BACKGROUND

Tubulointerstitial fibrosis is the final common pathway to end-stage renal failure. The present study investigated the potential role of tubular epithelial cells (TEC) in progressive fibrosis in the rat remnant kidney model.

METHODS

Rats underwent 5/6 nephrectomy or a sham operation (control), and groups of six animals were killed at weeks 1, 3, 5, 9, 13, 17 and 21.

RESULTS

Immunohistochemistry staining and in situ hybridization at week 3 after nephrectomy demonstrated de novo expression of alpha-smooth muscle actin (alpha-SMA)--a marker of smooth muscle cells and myofibroblasts--by TEC that was invariably associated with disruption of the tubular basement membrane (TBM). This phenotypic evidence of tubular epithelial-myofibroblast transdifferentiation was supported by ultrastructural studies identifying the presence of characteristic actin microfilaments and dense bodies within TEC with a transformed morphology. In the late stage of this apparent tubular epithelial-myofibroblast transdifferentiation, TEC lost apical-basal polarity and tight junctions, became elongated, detached from the TBM, separated from neighboring cells and appeared to migrate into the peritubular interstitium through the damaged basement membrane. Indeed, focal peritubular accumulation of alpha-SMA+ myofibroblasts and local tubulointerstitial fibrosis was closely associated with alpha-SMA+ tubules, suggesting a tubular epithelial origin for some of these cells. Quantitative analysis found a significant correlation between the number of alpha-SMA+ TEC and the accumulation of interstitial alpha-SMA+ myofibroblasts and the severity of tubulointerstitial fibrosis (both P < 0.001).

CONCLUSIONS

This study provides phenotypic and morphological evidence to support the hypothesis that TEC are pro-fibrogenitor cells capable of tubular epithelial-myofibroblast transdifferentiation in progressive renal fibrosis. In addition, we postulate that disruption of the TBM, which facilitates epithelial cell contact with the interstitial matrix, promotes this process of transdifferentiation.

Serum transferrin receptor concentration is not indicative of erythropoietic activity in chronic hemodialysis patients with poor response to recombinant human erythropoietin

BACKGROUND

Serum transferrin receptor (sTfR) is a transmembrane glycoprotein derived from erythroid precursors in the bone marrow. Its concentration provides a quantitative measure of total erythropoietic activity and an indication of functional iron deficiency. This study was conducted to investigate whether sTfR is a useful index of erythropoietic activity in chronic hemodialysis patients with poor response to maintenance recombinant human erythropoietin (rHuEPO) therapy.

METHODS

Using an enzyme-linked immunosorbent assay, sTfR concentration was measured in 67 uremic patients who had been on hemodialysis for a mean of 42 months (3-242 months). rHuEPO was administered three times a week to keep the hematocrit above 30%. Hemoglobin, red blood cell indices, serum ferritin, serum total iron binding capacity and unsaturated iron binding capacity were determined. Of the 67 patients, 35 who responded favorably to rHuEPO with hematocrits above 30% were categorized as Group I and 32 who did not attain the target hematocrit were categorized as Group II. As a control group, 31 healthy subjects were also investigated.

RESULTS

The serum iron, ferritin, transferrin iron saturation, dialysis efficiency and nutritional state were not different between groups of hemodialysis patients. The mean sTfR concentration was 2.1 +/- 0.6 micrograms/ml (range, 1.15-3.53 micrograms/ml) in Group I patients, compared with 1.9 +/- 0.9 micrograms/ml (range, 1.03-2.65 micrograms/ml) in Group II. The difference was not significant. In addition, the mean sTfR concentration of 1.8 +/- 0.4 micrograms/ml (range, 0.86-2.76 micrograms/ml) in the healthy controls was not significantly different from Groups I and II.

CONCLUSIONS

sTfR concentration cannot be used to distinguish good from poor rHuEPO responders among chronic hemodialysis patients who have elevated serum ferritin (> 300 micrograms/l) and transferrin iron saturation (> 25%) during the course of maintenance rHuEPO therapy.

Endothelin A-receptor blockade worsens endotoxin-induced hepatic microcirculatory changes and necrosis

BACKGROUND & AIMS

Endothelin 1 is considered to be an important regulator of sinusoidal blood flow and increases during endotoxemia. The purpose of this study was to investigate the role of endothelin 1 in hepatic microcirculation, oxygen transport, and liver injury during endotoxemia.

METHODS

Male Sprague-Dawley rats were continuously infused with 2.5 mL/h of saline, 0.8 mg . kg-1 . h-1 of lipopolysaccharide (LPS), 3 mg . kg-1 . h-1 of BQ-485, an endothelin A-receptor antagonist, or LPS plus BQ-485 for 7 hours.

RESULTS

BQ-485 infusion had no significant effect on hepatic microcirculation and liver injury. LPS increased the plasma levels of aspartate aminotransferase (AST) and total bilirubin and decreased the hepatic adenosine triphosphate (ATP) level and bile flow rate. LPS + BQ-485 infusion further increased the plasma levels of AST and total bilirubin and decreased the bile flow rate and the hepatic ATP level. Dual-spot microspectroscopy revealed mild decreases in sinusoidal erythrocyte velocity and oxygen transport in the LPS group and profound decreases in these parameters in the LPS + BQ-485 group. Histological examinations revealed massive necrotic changes in the pericentral regions of the LPS + BQ-485 group.

CONCLUSIONS

These results suggest that blockade of endothelin A receptors disturbs hepatic microcirculation and oxygen transport and aggravates the necrotic injury induced by endotoxin.

PCR diagnosis on formalin-fixed, paraffin-embedded tissues with acid-fast stain and culture negativity in chronic dialysis patients of cervico-mediastinal tuberculous lymphadenitis

BACKGROUND

Bacteriologic studies often provide negative results in tuberculous infection, and do not favour early diagnosis. Polymerase chain reaction (PCR) is known to diagnose tuberculosis quickly. With this in mind, we used PCR to detect mycobacterial DNA on formalin-fixed, paraffin-embedded tissues with acid-fast stain and culture negativity in two dialysis patients with cervico-mediastinal lymphadenopathy.

METHODS

Sections of neck lymph nodes were cut at two different levels. At each level, two semi-adjacent sections with a thickness of 5 microm each were cut using standard microtomes with disposable blades. The first section mounted on a glass slide was stained by Ziehl-Neelsen, and the second section was examined by PCR based on a 123 bp fragment of IS6110 that is specific for the Mycobacterium tuberculosis complex.

RESULTS

The histology of lymph nodes disclosed inflammatory necrotizing granulomas, but acid-fast stain for M. tuberculosis was negative in the two patients. DNA of M. tuberculosis was detected in lymph node samples from each patient by PCR on the IS6110 element and by dot-blot hybridization.

CONCLUSIONS

PCR assay is a potentially useful approach for early and rapid diagnosis of tuberculous lymphadenitis in chronic dialysis patients, since mycobacterial staining and culture often provide negative results.

Focal segmental glomerulosclerosis after poststreptococcal glomerulonephritis in the elderly: a case report

Acute poststreptococcal glomerulonephritis (PSGN) is quite rare in the elderly population. It is very difficult to recognize because the initial symptoms are similar to those of more common diseases of this age group. Compared with younger patients, elderly patients with PSGN tend to have a high incidence of renal function impairment and anuria or prolonged oliguria. Recovery from acute PSGN in the elderly is less predictable than in children and younger adults, especially when associated with severe impairment of renal function. We present the case of an elderly patient with PSGN, who had a skin infection of the face and anuria on admission. Percutaneous left renal biopsy was performed in the initial hospitalization period and in the recovery phase of the disease. Renal function recovered within two months. However, increased urinary white blood cell sediments with normal serum creatinine concentrations persisted in the successive three years of follow-up. Renal biopsy was repeated and showed evidence of focal segmental glomerulosclerosis.

Brachial plexus compression due to subclavian pseudoaneurysm from cannulation of jugular vein hemodialysis catheter

Jugular venous cannulation is generally safer than subclavian cannulation. The traumatic complications associated with jugular vein hemodialysis catheters are rare. A jugular vein, therefore, has become the preferred site for hemodialysis catheter insertion. We describe the first case of brachial plexus compression attributable to delayed recognition of a right subclavian pseudoaneurysm as a complication of jugular venous cannulation of hemodialysis catheter. We advocate that any neck swelling, new bruit, and the symptoms of brachial plexopathy after jugular venous cannulation warrant an intensive investigation to exclude arterial injury. Because delayed diagnosis may lead to a worsened prognosis in patients with brachial plexus palsy, physicians should exercise vigilance to detect and manage early the potentially serious and fatal complications of subclavian artery pseudoaneurysm and brachial nerve injury.

Anatomical variation of the internal jugular vein and its impact on temporary haemodialysis vascular access: an ultrasonographic survey in uraemic patients

BACKGROUND

Creation of a reliable haemoaccess is a critical problem for practicing nephrologists once haemodialysis has been considered. A double-lumen internal jugular-vein catheter is favoured in most cases requiring temporary haemoaccess. However, numerous complications, even lethal ones, may occur with the cannulating procedure. Using ultrasound, we attempted to describe the occult anatomical variations of vessels which may be responsible for complications.

METHODS

A 'SiteRite' ultrasonographic device was used to inspect the anatomical structure of the internal jugular veins (IJV) in 104 consecutive uraemic patients undergoing creation of internal jugular vein temporary angioaccess. Images of the vessels and demographic data of patients were recorded and analysed.

RESULTS

Anatomical variations of the right and left IJVs were found in 19 (18.3%) and 17 (16.4%) uraemic patients respectively. Unilateral IJV variations were found in 18 patients (17.3%) and bilateral variations were discovered in nine patients (8.7%). A total of 27 patients (26.0%) had IJV anatomical variations that might contribute to difficulty in external landmark-guided IJV cannulation.

CONCLUSIONS

The external anatomical landmarks for cannulating the IJV are not reliable in about one-quarter of uraemic patients. An ultrasound survey on the IJV anatomy is recommended for selecting proper puncture site and reducing risks of insertion complications for IJV dialysis catheters.

Low molecular weight heparin in diabetic and nondiabetic hypercholesterolemic patients receiving long-term hemodialysis

Dyslipidemia is a major factor associated with cardiovascular disease, which is the leading cause of death in hemodialysis patients. Low molecular weight heparin (LMWH) is superior to conventional unfractionated heparin in treating hyperlipidemia in nondiabetic long-term hemodialysis patients and has fewer side-effects. Only a few reports have addressed the influence of LMWH on serum lipids in diabetic patients, although dyslipidemia is common among this population. We investigated the effect of LMWH on serum lipids in 12 nondiabetic and eight diabetic hypercholesterolemic patients receiving long-term hemodialysis. Patients had been receiving hemodialysis with unfractionated heparin for a minimum of 6 months before beginning the study. Continuous LMWH infusion during hemodialysis was administered to all patients for 2 months, followed by unfractionated heparin administration for 2 months. During LMWH treatment, plasma anti-factor Xa activity increased from 0.06 +/- 0.04 IU/mL before dialysis to 0.49 +/- 0.25 IU/mL after 3 hours. Serum total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and apolipoprotein B (Apo B) in both nondiabetic and diabetic patient groups and lipoprotein (a) (Lp(a)) in patients with higher initial values (> or = 15 mg/mL) decreased significantly after LMWH treatment (TC from 6.38 +/- 1.14 to 5.07 +/- 1.09 mmol/L, LDL-C from 3.08 +/- 0.93 to 2.15 +/- 0.88 mmol/L, Apo B from 100 +/- 18 to 78 +/- 18 mg/dL, all p < 0.01; Lp(a) from 41.8 +/- 34.5 to 28.5 +/- 22.8, p < 0.05). They rebounded to pre-LMWH levels after the 2 months on unfractionated heparin (TC 5.72 +/- 1.11 mmol/L, LDL-C 2.97 +/- 1.01 mmol/L, Apo B 98 +/- 20 mg/dL, Lp(a) 38.1 +/- 29.0 mg/dL). We conclude that continuous infusion of LMWH during dialysis reduces serum total cholesterol, low-density lipoprotein-cholesterol, and apolipoprotein B concentrations in both diabetic and nondiabetic hypercholesterolemic hemodialysis patients, and does not increase the risk of bleeding compared with unfractionated heparin.

Persistent transforming growth factor beta 1 expression may predict peritoneal fibrosis in CAPD patients with frequent peritonitis occurrence

The efficiency of continuous ambulatory peritoneal dialysis (CAPD) depends on the permeability of the peritoneal membrane. Peritoneal fibrosis (PF) causes the loss of dialytic function. Several studies have indicated that PF is closely related to the proliferation of peritoneal fibroblasts and the deposition of extracellular matrix (ECM). Transforming growth factor beta 1 (TGF beta 1) plays a major role in stimulating ECM deposition. Frequent peritonitis occurrence may cause persistent TGF beta 1 mRNA expression. In an attempt to search for a factor related to PF, we designed a longitudinal study to measure TGF beta 1 levels in dialysate and TGF beta 1 mRNA expression in peritoneal mononuclear cells (PMNCs) from peritoneal dialysate before, at the onset of and once a week during peritonitis and after peritonitis in patients with high peritonitis occurrence (HPO) and patients with low peritonitis occurrence (LPO). Fifteen patients with a LPO rate and 5 patients with a HPO rate were followed up longitudinally. Meanwhile, TGF beta 1 levels and TGF beta 1 mRNA expression were augmented in peritoneal dialytic fluid before, during, and after the episodes of peritonitis. Peritoneal permeability was evaluated by the peritoneal equilibration test (PET). The results revealed that in the LPO group, TGF beta 1 and TGF beta 1 mRNA were detectable at early stages of peritonitis, but the levels decreased rapidly and were undetectable 2 weeks after peritonitis. On the other hand, in the HPO group, TGF beta 1 and TGF beta 1 mRNA persisted for a long time. We could detect TGF beta 1 and TGF beta 1 mRNA in dialytic fluid and PMNCs even 2, 3, and 4 weeks after episodes of peritonitis. When compared with that of the first or second episode of peritonitis, peritoneal function evaluated with the PET was found to obviously deteriorate at the third episode of peritonitis. These findings were confirmed by an in situ hybridization technique to evaluate the relationship between TGF beta 1 mRNA expression and PF from biopsied peritoneal specimens. These findings suggest that the high TGF beta 1 levels in the dialysate are related to an increased expression of TGF beta 1 in the peritoneum. Persistent TGF beta 1 expression in the peritoneum may serve as a useful parameter in predicting PF in CAPD patients with frequent peritonitis occurrence.

Absence of modulating effects of cytokines on antioxidant enzymes in peritoneal mesothelial cells

OBJECTIVE

To investigate the modulation of superoxide dismutase, glutathione peroxidase, and catalase by cytokines and endotoxin in human peritoneal mesothelial cells.

DESIGN

Cultured human peritoneal mesothelial cells were treated with various concentrations of interleukin-1 alpha, tumor necrosis factor-alpha (TNF-alpha), interleukin-6, interleukin-8, transforming growth factor-beta (TGF beta), and lipopolysaccharide. Cell morphology was observed and the activities of superoxide dismutase, catalase, and glutathione peroxidase were assayed. The antioxidant enzyme activities of human peritoneal mesothelial cells were also compared with those of human liver and kidney tissues.

RESULTS

Interleukin-1 alpha, TNF alpha, TGF beta, and lipopolysacharide caused dose-dependent cytotoxicities in mesothelial cells. The activities of these three antioxidant enzymes did not change after treatment with cytokines and endotoxin. The total superoxide dismutase activity of confluent human peritoneal mesothelial cells was found to be greater than that of human liver and kidney tissues and was composed mostly of manganese superoxide dismutase activity. Furthermore, glutathione peroxidase and catalase activities of human peritoneal mesothelial cells were lower than those of human liver and kidney tissues.

CONCLUSION

In human peritoneal mesothelial cells, lack of induction of antioxidant enzymes by inflammatory cytokines, as well as high superoxide dismutase activity accompanied by insufficient glutathione peroxidase and catalase activities may both contribute to the susceptibility of these cells to oxidative damage. Therefore, appropriate management to decrease oxidative injury to the peritoneum should be taken into consideration when treating long-term continuous ambulatory peritoneal dialysis patients.

Role of nitric oxide in oxygen transport in rat liver sinusoids during endotoxemia

To evaluate the role of nitric oxide (NO) in hepatic microcirculation and liver injury during endotoxemia, we studied O2 transport in the hepatic microcirculation of endotoxin-infused rats. Rats were continuously infused with Escherichia coli lipopolysaccharide (LPS) (0.8 mg/kg/h) for 7 hours. LPS increased the plasma levels of NO2- + NO3- and aspartate transaminase (AST), and decreased the bile flow rate and hepatic adenosine triphosphate (ATP) level. Hepatic microcirculation was evaluated by two methods: reflectance spectrophotometry showed a decrease in the oxygenation of hemoglobin (Hb) in the liver, and dual-spot microspectroscopy indicated that LPS administration decreased blood velocity, the oxygenation of Hb, and O2 release from sinusoids to hepatocytes. The observed decreases in the O2 transport parameters were prominent in pericentral sinusoids. All of these phenomena were further aggravated by the administration of N(w)-nitro-L-arginine methyl ester (L-NAME) (5 mg/kg/h) plus LPS, and by aminoguanidine (AMG) (5 mg/kg/h) plus LPS, and these could be reversed by the concomitant administration of L-arginine (L-Arg) (100 mg/kg/h). These results suggest that deterioration of hepatic oxygen transport and liver function induced by endotoxin can be ameliorated by NO.

Resistance to recombinant erythropoietin in a hemodialysis patient with heterozygous hemoglobinopathy J-Meinung

The mechanism of resistance to recombinant human erythropoietin (EPO) in hemodialysis patients with hemoglobinopathy is not yet fully understood. Poor responses to EPO have been reported in anemic dialysis patients with sickle cell disease and thalassemia. We present the first case of a hemodialysis patient with EPO resistance and hemoglobin J-Meinung, which is initially found by hemoglobin electrophoresis and finally proven by molecular genetic analysis. Additionally, the patient was diagnosed as having chronic active hemolysis with hallmarks of splenomegaly, an increased serum bilirubin and reticulocyte index, and a reduced haptoglobin level. We discuss the possible mechanisms and proper treatment options in such patients with a poor response to EPO.

Uremic pruritus: roles of parathyroid hormone and substance P

BACKGROUND

Most patients receiving maintenance hemodialysis have pruritus, but its underlying mechanism remains unknown. Secondary hyperparathyroidism is another common problem in these patients, but its role in uremic pruritus is controversial. Capsaicin can deplete substance P from the peripheral neurons and is known to be effective in the treatment of pain and itching.

OBJECTIVE

Our purpose was to evaluate the role of parathyroid hormone (PTH) and substance P in uremic pruritus and to elucidate the underlying mechanisms.

METHODS

The study contained two phases. In phase I, we analyzed the correlation between the intensity of itching and serum levels of intact PTH. In phase II, patients with moderate to severe pruritus were placed into two groups: one with high PTH levels and one with low levels. A double-blind, placebo-controlled study of capsaicin 0.025% cream was conducted in phase II.

RESULTS

Serum levels of intact PTH did not correlate with the intensity of pruritus and did not significantly change during treatment with capsaicin or placebo. Capsaicin was significantly more effective in alleviating uremic pruritus than the placebo, and no serious side effects were noted.

CONCLUSION

Uremic pruritus is not related to PTH. Substance P may act as a neurotransmitter in uremic pruritus and topical capsaicin can be used in the treatment of localized pruritus.

Peritoneal dialysis solution induces apoptosis of mesothelial cells

For better simulation of the long-dwell exchanges in conventional CAPD, we have developed a modified mesothelial cell culture system consisting of a Transwell culture apparatus. The equilibration patterns of pH, dextrose and osmolality in the present culture system were observed to be very similar to those in human CAPD. The effects of six different peritoneal dialysis solutions on the apoptosis of mesothelial cells were evaluated using this modified culture system. The results imply that peritoneal dialysis solution per se may incite apoptosis of mesothelial cells, and also that low calcium peritoneal dialysis solution is a milder apoptosis stimulant as compared to the conventional peritoneal dialysis solution. Moreover, varying concentrations of dextrose in the peritoneal dialysis solution were not observed to significantly affect the apoptosis rate. The roles of ambient high concentrations of calcium and dextrose, low pH, as well as high osmolality in the apoptosis are also discussed.

Mathematical approach for estimating iron needs in hemodialysis patients on erythropoietin therapy

Functional iron deficiency occurs when recombinant human erythropoietin (rHuEPO) accelerates erythropoiesis to an extent that the iron availability cannot meet the anticipated demand. Such a phenomenon will reduce the optimal response to rHuEPO. To estimate the iron needs of functional iron deficiency in hemodialysis patients on rHuEPO therapy, we utilized a mathematical method. Forty hemodialysis patients were examined in the study, and all had a baseline serum ferritin (SF) level > 100 microg/l. They were stratified into patients with a transferrin saturation (TfS) value > or = 25% (group I) and those below this value (group II). The treatment protocol consisted of rHuEPO therapy in the two groups for 6 months and iron supplement only in group II. The target hemoglobin level was 10.5 g/dl, and iron metabolism indices were analyzed prior to and following therapy. The results showed (1) in group I (n = 20) hemoglobin rose from 7.5 +/- 0.9 to 10.7 +/- 0.7 g/dl (p < 0.01) and the mean SF level declined from 1,583 +/- 997 to 968 +/- 664 mg (p < 0.01); (2) in group II (n = 20) hemoglobin also increased from 7.8 +/- 0.9 to 10.6 +/- 0.8 g/dl (p < 0.01) following iron supplement, while the SF rose from 183 +/- 70 to 326 +/- 125 mg (p < 0.01); (3) TfS was significantly elevated in group II following iron therapy (18.9 +/- 4.8 vs. 34.5 +/- 9.1%, p < 0.01), and (4) the nomogram showed a sensitivity of 80%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 83% in estimating the iron status before rHuEPO therapy. We conclude that SF levels reflect iron stores and that TfS < 25% is an index of functional iron deficiency. Iron supplementation is not necessary in patients with SF > 100 microg/l and TfS > or = 25%. It seems rational to provide intravenous iron in EPO-resistant patients with functional iron deficiency (SF > 100 microg/l, TfS < 25%). This paper illustrates the importance that accurate assessment of iron needs by a mathematical method would enhance treatment efficacy and avoid iron overload in hemodialysis patients on rHuEPO therapy.

Improvement of rat liver graft function by insulin administration to donor

BACKGROUND & AIMS

The nutritional status of a donor is considered to be an important factor affecting organ viability. The purpose of the present study was to examine hepatic energy status in connection with posttransplantation liver function.

METHODS

The following five groups of donor rat livers were prepared and stored in University of Wisconsin solution at 4 degrees C: fasted group, rats fasted for 24 hours; fed group, rats provided standard laboratory chow; fed plus insulin group, fed rats treated with insulin before harvest; fasted plus insulin group, fasted rats treated with insulin before harvest; and fed plus glucagon group, fed rats pretreated with glucagon.

RESULTS

Hepatic levels of adenosine triphosphate and total adenine nucleotides were maintained in the decreasing order of the fed plus insulin, fed, fasted plus insulin, fasted, and fed plus glucagon groups during preservation. Lactate production rate and fructose 2,6-bisphosphate level increased in the order of the fed plus insulin, fed, fed plus glucagon, fasted, and fasted plus insulin groups. Liver function after transplantation evaluated by the bile flow rate and enzyme leakage was well restored in the fed plus insulin group.

CONCLUSIONS

Insulin administration to nutritionally well-supported livers before harvest improved energy metabolism during preservation and liver function after transplantation.

The removal index for evaluation of dialysis

OBJECTIVES

To find an index of adequacy that takes into consideration the effect of the decreasing concentration of urea nitrogen in hemodialysis (HD) and can be used before treatments to quantitate the prescriptions with the same criterion for both HD and continuous ambulatory peritoneal dialysis (CAPD).

DESIGN

The removal index was obtained through mathematical theories and then compared with the urea index (KT/V) values of the sample patients.

PATIENTS

Thirty-two HD and 21 CAPD patients were included. All patients were dialyzed with optimal urea index values and had been stable for at least one year.

RESULTS

The removal index in HD (xi HD) for each dialysis was O.62 +/- 0.07, and the normalized removal index in CAPD (xi CAPD) was 0.59 +/- 0.11. There was no statistical significance. This result is consistent with the fact that no difference of morbidity or mortality exists between these two modalities.

CONCLUSION

After mathematical manipulation, the removal index in HD can be presented in the form of the urea reduction ratio, which is a retrospective measure to estimate the performance of hemodialysis. This study implies that the removal index is able to facilitate the prescriptions for adequate dialysis. The removal index can also be used to explain the reason why the urea index values are always larger in HD than in CAPD.

Hemodialysis-related pruritus: a double-blind, placebo-controlled, crossover study of capsaicin 0.025% cream

Pruritus is a significant symptom among patients receiving hemodialysis. However, its underlying mechanisms remain obscure. Substance P, a neuropeptide, has been implicated in the mediation of pain and some itch sensations. Local application of capsaicin depletes the peripheral neurons of substance P and may block the conduction of pain or pruritus. This study aims to assess the efficacy and safety of capsaicin 0.025% cream in the treatment of hemodialysis-related pruritus and to further explore the underlying pathomechanism. Nineteen hemodialysis patients with idiopathic, moderate (n = 5) to severe (n = 14) pruritus were examined in a double-blind, placebo-controlled, crossover study and 17 of them completed the study. Topical agent of capsaicin or placebo base cream was applied to localized areas of pruritus 4 times a day. The severity of pruritus and treatment-related side effects (cutaneous burning/stinging sensations, dryness, or erythema) were evaluated weekly. The results showed (1) that 14 of 17 patients reported marked relief and 5 of these 14 patients had complete remission of pruritus during capsaicin treatment (Wilcoxon signed-ranks test, 2p < 0.001); (2) capsaicin was significantly more effective than placebo (Mann-Whitney rank sum test, 2p < 0.001) and a prolonged antipruritic effect was observed 8 weeks posttreatment; (3) no serious side effects were noted during the study and (4) there were no significant changes in serum concentrations of albumin, calcium, phosphorus, alkaline phosphatase, or intact parathyroid hormone during the treatment with either capsaicin or placebo. In summary, the present study indicates indirectly that idiopathic pruritus in some patients on maintenance hemodialysis may be transmitted by substance P from the peripheral sensory neurons to the central nervous system. Topical capsaicin with the unique pharmacological effect is demonstrated to markedly improve the pruritus of these patients.

Dialyzer reuse: interaction between dialyzer membrane, disinfectant (formalin), and blood during dialyzer reprocessing

The growing practice of dialyzer reuse in recent years is mainly based on medical and economic considerations. However, adverse reactions such as immunohemolytic anemia due to anti-Nform antibody associated with dialyzer reuse have been reported. In this study, scanning electron microscopy and cytologic staining were used to evaluate the interaction between blood components and the reprocessed synthetic dialyzer membrane (polysulfone) after disinfectant (formaldehyde) treatment. The results showed that various blood components such as fibrin and blood cells still adhered to the dialyzer membrane after reprocessing. The study also demonstrated that the adhered denatured blood components could be detached by sonication and/or simulated hemodialysis and then gain access into the circulation. The re-entry of the denatured blood components to the patients exposed to reused dialyzers may result in an enhanced immunological response which may contribute to antibody formation (such as anti-Nform antibody) with a reused hemodialyzer.

Increased excretion of tumor necrosis factor alpha and interleukin 1 beta in urine from patients with IgA nephropathy and Schönlein-Henoch purpura

Urinary proteins (5 mg/ml) collected from a group of 16 patients including 13 with IgA nephropathy and 3 with Schönlein-Henoch purpura (SHP) and from a control group consisting of 6 patients with diabetic nephropathy, 5 patients with hypertensive nephrosclerosis, and 5 healthy hospital staff members were studied for the contents of interleukins (IL) 1 beta, 2, 4, 6, and 12 and tumor necrosis factor alpha (TNF-alpha). Eleven patient with IgA nephropathy or SHP (11/16) but only 1 of the controls (1/16) had TNF-alpha activity in urinary proteins (p < 0.01). The IL-1 beta activity exhibited a similar tendency but to a lesser extent (10 of 16 patients with IgA nephropathy or SHP vs. 2 of 16 with other conditions, p < 0.05). Conversely, the detection rates of IL-2, IL-4, and IL-6 in both groups were not significantly different. IL-12 was not found in any of the samples from both groups. Sera and nonpurified urine samples from the same individuals were also measured for cytokines. IL-1 beta, IL-2, IL-4, and IL-12 were absent in all these samples, but TNF-alpha was found in four of the serum samples from patients with IgA nephropathy. Urinary proteins (2 mg/ml) were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereby peptides of 52, 49, 45, 34, 30, and 11 kD could be demonstrated in the patients with IgA nephropathy or SHP. Urinary proteins (200 micrograms/ml from patients with IgA nephropathy or SHP exerted a mitogen-like effect on the normal human mononuclear cells, as demonstrated by 3H-thymidine incorporation. In addition, these urinary proteins (400 micrograms/ml) enhanced the proliferative activity of the cultured rat glomerular mesangial cells. The exaggerated proliferation of rat glomerular mesangial cells exerted by urine proteins from 2 patients with active disease was markedly suppressed after treatment with glucocorticoids/cyclophosphamide. These results suggest that patients with IgA nephropathy or SHP can excrete excessive amounts of TNF-alpha and IL-1 beta in the urine. The inconsistent presence of these two cytokines in urine and serum may indicate that they can be produced locally and that they are implicated in the development of mesangial inflammation and glomerular damage.

Iron metabolism indices for early prediction of the response and resistance to erythropoietin therapy in maintenance hemodialysis patients

A prospective study with 65 maintenance hemodialysis (MHD) patients on recombinant human erythropoietin (rHuEPO) therapy was conducted to assess the effect of iron balance on responsiveness. An attempt to define the predictors of erythropoietin (EPO) response and identify the specific causes of EPO resistance was undertaken in the present study. The treatment protocol consisted of two stages, the first was rHuEPO therapy for 6 months and the second was iron supplementation plus rHuEPO therapy in patients without response to EPO for the next 6 months. According to the hemoglobin (Hb) changes (increment exceeded 30% of baseline or did not exceed 15% of baseline for 3 consecutive months) and whether or not there was an achievement of target Hb level (>10.5 g/dl), all patients (n = 65) were divided into EPO-responsive (n = 20) and EPO-resistant (n = 45) groups. The EPO-resistant patients were then further stratified into iron-responsive (n = 29) and iron-irresponsive (n=16) groups. Iron metabolism and red cell indices were analyzed prior to and following rHuEPO therapy and iron supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraperitoneal recombinant human erythropoietin therapy: influence of the duration of continuous ambulatory peritoneal dialysis treatment and peritonitis

This study was performed to investigate the factors that influence intraperitoneal absorption of recombinant human erythropoietin (rHuEPO) and to evaluate the differences of the pharmacokinetics of intraperitoneally administered rHuEPO before peritonitis and after recovery. First, the pharmacokinetics in different groups of continuous ambulatory peritoneal dialysis (CAPD) patients was studied. Thirty-six CAPD patients were enrolled and divided into four groups. Group 1 included 20 patients who were either just placed on CAPD therapy or had been on CAPD for < 1 year, but with a low frequency of peritonitis episodes. Group 1 was divided into four subgroups by body weight (20-30, 31-45, 46-55, and > 55 kg). Group 2, patients who had received CAPD treatment for more than 1 year, was further divided into group 2a and group 2b according to a low or a high frequency of peritonitis episodes, respectively. rHuEPO (100 U/kg) was administered as a single bolus of intravenous, subcutaneous, or intraperitoneal injection. Intraperitoneal rHuEPO was retained for 10 h. The results showed no significant differences between subcutaneous and intraperitoneal administration in group 1 patients. However, peak concentration, time to reach peak serum level, area under the curves, and bioavailability were substantially lower after intraperitoneal than after subcutaneous administration in group 2a and group 2b patients. There was no influence of body size on peak concentration and area under the curve in group 1 patients. Second, comparison of the pharmacokinetics of intraperitoneal administration before and after recovery from peritonitis in group 1 patients revealed that the serum levels of rHuEPO became lower after the occurrence of peritonitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal function in gout patients

Patients with gouty arthritis were examined at Veterans General Hospital to evaluate whether their renal function is impaired and to define the factor(s), if any, of renal function deterioration. A total of 152 cases were included in the study, and the patients were divided into two groups. One group (n = 80) exhibited pure gout without any associated medical problems or preexisting renal disorders. The second group (n = 72) included patients with gout and hypertension. The group with pure gout was further stratified into patients with tophi (n = 21) and those without (n = 59). Seventy-two sex- and age-matched normal adults served as the control group. We found (1) that the renal function was impaired in the pure-gout group when compared with sex- and age-matched normal individuals (serum creatinine 1.56 +/- 0.64 vs. 0.90 +/- 0.16 mg/dl, p = 0.0001; creatinine clearance 59.91 +/- 30.90 vs. 97.10 +/- 27.19 ml/min, p = 0.0001); (2) that the renal function was significantly more aggravated in patients with clinically visible tophi than in those without (gout with tophi vs. gout without tophi: serum creatinine 1.89 +/- 0.90 vs. 1.44 +/- 0.48 mg/dl, p = 0.040; creatinine clearance 47.27 +/- 31.90 vs. 64.40 +/- 29.53 ml/min, p = 0.030), and (3) that a further significant decline of the renal function was noted in gouty patients with an associated medical illness, i.e., hypertension (gout with hypertension vs. pure gout: serum creatinine 2.10 +/- 0.97 vs. 1.56 +/- 0.64 mg/dl, p = 0.0001; creatinine clearance 45.06 +/- 24.69 vs. 59.91 +/- 30.90 ml/min, p = 0.0029).(ABSTRACT TRUNCATED AT 250 WORDS)