Balanced crystalloid solution versus saline in deceased donor kidney transplantation (BEST-Fluids): a pragmatic, double-blind, randomised, controlled trial

BACKGROUND

Delayed graft function (DGF) is a major adverse complication of deceased donor kidney transplantation. Intravenous fluids are routinely given to patients receiving a transplant to maintain intravascular volume and optimise graft function. Saline (0·9% sodium chloride) is widely used but might increase the risk of DGF due to its high chloride content. We aimed to test our hypothesis that using a balanced low-chloride crystalloid solution (Plasma-Lyte 148) instead of saline would reduce the incidence of DGF.

METHODS

BEST-Fluids was a pragmatic, registry-embedded, multicentre, double-blind, randomised, controlled trial at 16 hospitals in Australia and New Zealand. Adults and children of any age receiving a deceased donor kidney transplant were eligible; those receiving a multi-organ transplant or weighing less than 20 kg were excluded. Participants were randomly assigned (1:1) using an adaptive minimisation algorithm to intravenous balanced crystalloid solution (Plasma-Lyte 148) or saline during surgery and up until 48 h after transplantation. Trial fluids were supplied in identical bags and clinicians determined the fluid volume, rate, and time of discontinuation. The primary outcome was DGF, defined as receiving dialysis within 7 days after transplantation. All participants who consented and received a transplant were included in the intention-to-treat analysis of the primary outcome. Safety was analysed in all randomly assigned eligible participants who commenced surgery and received trial fluids, whether or not they received a transplant. This study is registered with Australian New Zealand Clinical Trials Registry, (ACTRN12617000358347), and ClinicalTrials.gov (NCT03829488).

FINDINGS

Between Jan 26, 2018, and Aug 10, 2020, 808 participants were randomly assigned to balanced crystalloid (n=404) or saline (n=404) and received a transplant (512 [63%] were male and 296 [37%] were female). One participant in the saline group withdrew before 7 days and was excluded, leaving 404 participants in the balanced crystalloid group and 403 in the saline group that were included in the primary analysis. DGF occurred in 121 (30%) of 404 participants in the balanced crystalloid group versus 160 (40%) of 403 in the saline group (adjusted relative risk 0·74 [95% CI 0·66 to 0·84; p<0·0001]; adjusted risk difference 10·1% [95% CI 3·5 to 16·6]). In the safety analysis, numbers of investigator-reported serious adverse events were similar in both groups, being reported in three (<1%) of 406 participants in the balanced crystalloid group versus five (1%) of 409 participants in the saline group (adjusted risk difference -0·5%, 95% CI -1·8 to 0·9; p=0·48).

INTERPRETATION

Among patients receiving a deceased donor kidney transplant, intravenous fluid therapy with balanced crystalloid solution reduced the incidence of DGF compared with saline. Balanced crystalloid solution should be the standard-of-care intravenous fluid used in deceased donor kidney transplantation.

FUNDING

Medical Research Future Fund and National Health and Medical Research Council (Australia), Health Research Council (New Zealand), Royal Australasian College of Physicians, and Baxter.

Study protocol for Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID)

Background

A functioning vascular access (VA) is crucial to providing adequate hemodialysis (HD) and considered a critically important outcome by patients and healthcare professionals. A validated, patient-important outcome measure for VA function that can be easily measured in research and practice to harvest reliable and relevant evidence for informing patient-centered HD care is lacking. Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID) aims to assess the accuracy and feasibility of measuring a core outcome for VA function established by the international Standardized Outcomes in Nephrology (SONG) initiative.

Methods

VALID is a prospective, multi-center, multinational validation study that will assess the accuracy and feasibility of measuring VA function, defined as the need for interventions to enable and maintain the use of a VA for HD.

The primary objective is to determine whether VA function can be measured accurately by clinical staff as part of routine clinical practice (Assessor 1) compared to the reference standard of documented VA procedures collected by a VA expert (Assessor 2) during a 6-month follow-up period. Secondary outcomes include feasibility and acceptability of measuring VA function and the time to, rate of, and type of VA interventions.

An estimated 612 participants will be recruited from approximately 10 dialysis units of different size, type (home-, in-center and satellite), governance (private versus public), and location (rural versus urban) across Australia, Canada, Europe, and Malaysia.

Validity will be measured by the sensitivity and specificity of the data acquisition process. The sensitivity corresponds to the proportion of correctly identified interventions by Assessor 1, among the interventions identified by Assessor 2 (reference standard). The feasibility of measuring VA function will be assessed by the average data collection time, data completeness, feasibility questionnaires and semi-structured interviews on key feasibility aspects with the assessors.

Discussion

Accuracy, acceptability, and feasibility of measuring VA function as part of routine clinical practice are required to facilitate global implementation of this core outcome across all HD trials. Global use of a standardized, patient-centered outcome measure for VA function in HD research will enhance the consistency and relevance of trial evidence to guide patient-centered care.

Trial registration

Clinicaltrials.gov: NCT03969225. Registered on 31st May 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02987-1.

Conducting clinical trials during the COVID-19 pandemic-a collaborative trial network response

The unprecedented demand placed on healthcare systems from the COVID-19 pandemic has forced a reassessment of clinical trial conduct and feasibility. Consequently, the Australasian Kidney Trials Network (AKTN), an established collaborative research group known for conducting investigator-initiated global clinical trials, had to efficiently respond and adapt to the changing landscape during COVID-19. Key priorities included ensuring patient and staff safety, trial integrity and network sustainability for the kidney care community. New resources have been developed to enable a structured review and contingency plan of trial activities during the pandemic and beyond.

Effect of a medium cut-off dialyzer on protein-bound uremic toxins and mineral metabolism markers in patients on hemodialysis

INTRODUCTION

Hemodialysis (HD) with medium cut-off (MCO) dialyzers may expand molecular clearance, predominantly larger middle molecules (molecular weight 25-60 kDa). However, the impact of MCO dialyzers on long-term clearance of various other components of the uremic milieu is unknown. The tRial Evaluating Mid cut-Off Value membrane clearance of Albumin and Light chains in HemoDialysis patients (REMOVAL-HD) provided an opportunity to assess the effect of MCO dialyzers on protein-bound uremic toxins and novel markers of mineral metabolism.

METHODS

This exploratory sub-study of REMOVAL-HD evaluated changes in protein-bound solutes (total and free indoxyl sulfate [IS] and p-cresyl sulfate [PCS]) and mineral metabolism markers (intact fibroblast growth factor-23 [iFGF23], fetuin-A and endogenous calciprotein particles [CPP-1 and CPP-2]). Mid-week, pre-HD serum samples were collected at baseline and after 12 and 24 weeks of MCO use in stable adult patients. Change from baseline to Week 12 and 24 was estimated using linear mixed effects models.

FINDINGS

Eighty-nine participants were studied (mean age 67 ± 15 years, 38% female, 51% diabetic, median urine output 200 ml/24 h). Serum iFGF23 was reduced at Week 12 compared to baseline (-26.8% [95%CI -39.7, -11.1], p = 0.001), which was sustained at Week 24 (-21.7% [95%CI -35.7, -4.5], p = 0.012). There was no significant change in serum IS, PCS, fetuin-A, CPP-1, or CPP-2.

DISCUSSION

The use of a MCO dialyzer over 24 weeks was associated with a sustained reduction in FGF23, while other measured components of the uremic milieu were not significantly altered. Further studies are required to determine whether FGF23 reduction is associated with improved patient outcomes.

Study Protocol for Better Evidence for Selecting Transplant Fluids (BEST-Fluids): a pragmatic, registry-based, multi-center, double-blind, randomized controlled trial evaluating the effect of intravenous fluid therapy with Plasma-Lyte 148 versus 0.9% saline on delayed graft function in deceased donor kidney transplantation

Background

Delayed graft function, the requirement for dialysis due to poor kidney function post-transplant, is a frequent complication of deceased donor kidney transplantation and is associated with inferior outcomes and higher costs. Intravenous fluids given during and after transplantation may affect the risk of poor kidney function after transplant. The most commonly used fluid, isotonic sodium chloride (0.9% saline), contains a high chloride concentration, which may be associated with acute kidney injury, and could increase the risk of delayed graft function. Whether using a balanced, low-chloride fluid instead of 0.9% saline is safe and improves kidney function after deceased donor kidney transplantation is unknown.

Methods

BEST-Fluids is an investigator-initiated, pragmatic, registry-based, multi-center, double-blind, randomized controlled trial. The primary objective is to compare the effect of intravenous Plasma-Lyte 148 (Plasmalyte), a balanced, low-chloride solution, with the effect of 0.9% saline on the incidence of delayed graft function in deceased donor kidney transplant recipients. From January 2018 onwards, 800 participants admitted for deceased donor kidney transplantation will be recruited over 3 years in Australia and New Zealand. Participants are randomized 1:1 to either intravenous Plasmalyte or 0.9% saline peri-operatively and until 48 h post-transplant, or until fluid is no longer required; whichever comes first. Follow up is for 1 year. The primary outcome is the incidence of delayed graft function, defined as dialysis in the first 7 days post-transplant. Secondary outcomes include early kidney transplant function (composite of dialysis duration and rate of improvement in graft function when dialysis is not required), hyperkalemia, mortality, graft survival, graft function, quality of life, healthcare resource use, and cost-effectiveness. Participants are enrolled, randomized, and followed up using the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry.

Discussion

If using Plasmalyte instead of 0.9% saline is effective at reducing delayed graft function and improves other clinical outcomes in deceased donor kidney transplantation, this simple, inexpensive change to using a balanced low-chloride intravenous fluid at the time of transplantation could be easily implemented in the vast majority of transplant settings worldwide.

Trial registration

Australian New Zealand Clinical Trials Registry: ACTRN12617000358347. Registered on 8 March 2017. ClinicalTrials.gov: NCT03829488. Registered on 4 February 2019.

A tRial Evaluating Mid Cut-Off Value Membrane Clearance of Albumin and Light Chains in HemoDialysis Patients: A Safety Device Study

BACKGROUND

A new class of dialysis membrane, the mid cut-off (MCO) dialyzer, has been developed to improve the clearance of uremic toxins in hemodialysis (HD). The a tRial Evaluating Mid cut-Off Value membrane clearance of Albumin and Light chains in HemoDialysis patients (REMOVAL-HD) study aimed to determine if regular use of MCO dialyzer was safe and specifically did not result in a significant loss of albumin.

METHODS

This investigator initiated, crossover, longitudinal, device study was conducted across 9 centers in Australia and New Zealand (n = 89). Participants had a 4-week wash-in with high-flux HD, followed by 24-week intervention with MCO HD and a subsequent 4-week wash-out with high-flux HD. The primary outcome was change in serum albumin between weeks 4 and 28. Secondary outcomes included trends in serum albumin, changes in kappa- and lambda-free light chains (FLC), 6-min walk test (6MWT), malnutrition inflammation score (MIS), restless legs score and quality of life.

RESULTS

Participants had a mean age of 66 ± 14 years, 62% were men, 45% were anuric, and 51% had -diabetes. There was no reduction in serum albumin following treatment with MCO HD (mean reduction -0.7 g/L, 95% CI -1.5 to 0.1). A sustained, unexplained reduction in serum albumin (>25%) was not observed in any participant. A reduction in FLC was observed 2 weeks into MCO HD (lambda-FLC: Δ -9.1 mg/L, 95% CI -14.4 to -3.7; kappa-FLC: Δ -5.7 mg/L, 95% CI -9.8 to -1.6) and was sustained for the rest of the study intervention. Both FLC increased after the cessation of MCO use. There was no improvement in restless legs symptoms, quality of life, 6MWT or MIS scores.

CONCLUSIONS

Regular HD using the MCO dialyzer did not result in a significant fall in serum albumin. There were no effects on quality of life, functional status or nutrition.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry Number (ANZCTRN) 12616000804482.

Association between serum hepcidin-25 and primary resistance to erythropoiesis-stimulating agents in chronic kidney disease: a secondary analysis of the HERO trial

BACKGROUND

Pentoxifylline has been shown to increase haemoglobin levels in patients with chronic kidney disease (CKD) and erythropoietin-stimulating agent (ESA)-hyporesponsive anaemia in the Handling Erythropoietin Resistance with Oxpentifylline multicentre double-blind, randomized controlled trial. The present sub-study evaluated the effects of pentoxifylline on the iron-regulatory hormone hepcidin in patients with ESA-hyporesponsive CKD.

METHODS

This sub-study included 13 patients in the pentoxifylline arm (400 mg daily) and 13 in the matched placebo arm. Hepcidin-25 was measured by ultra performance liquid chromatography/quadrupole time-of-flight mass spectrometry following isolation from patient serum. Serum hepcidin-25, serum iron biomarkers, haemoglobin and ESA dosage were compared within and between the two groups.

RESULTS

Hepcidin-25 concentration at 4 months adjusted for baseline did not differ significantly in pentoxifylline versus placebo treated patients (adjusted mean difference (MD) -7.9 nmol, P = 0.114), although the difference between the groups mean translated into a >25% reduction of circulating hepcidin-25 due to pentoxifylline compared with the placebo baseline. In paired analysis, serum hepcidin-25 levels were significantly decreased at 4 months compared with baseline in the pentoxifylline group (-5.47 ± 2.27 nmol/l, P < 0.05) but not in the placebo group (2.82 ± 4.29 nmol/l, P = 0.24). Pentoxifylline did not significantly alter serum ferritin (MD 55.4 mcg/l), transferrin saturation (MD 4.04%), the dosage of ESA (MD -9.93 U/kg per week) or haemoglobin concentration (MD 5.75 g/l).

CONCLUSION

The reduction of circulating hepcidin-25 due to pentoxifylline did not reach statistical significance; however, the magnitude of the difference suggests that pentoxifylline may be a clinically and biologically meaningful modulator of hepcidin-25 in dialysis of patients with ESA-hyporesponsive anaemia.

Representativeness of Honeypot Trial Participants to Australasian PD Patients

BACKGROUND

The HONEYPOT trial failed to establish the superiority of exit-site application of Medihoney compared with nasal mupirocin prophylaxis for the prevention of peritonitis in peritoneal dialysis (PD) patients. This study aimed to assess the representativeness of the patients in the HONEYPOT trial to the Australian and New Zealand PD population.

METHODS

This study compared baseline characteristics of the 371 PD patients in the HONEYPOT trial with those of 6,085 PD patients recorded on the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry.

RESULTS

Compared with the PD population, the HONEYPOT sample was older (standardized difference [d] = 0.19, p = 0.003), more likely to be treated with automated PD (d = 0.58, p < 0.001), had higher residual renal function (d = 0.26, p < 0.001) and a higher proportion of participants with end-stage kidney disease due to polycystic kidney disease (d = 0.17) and lower proportion due to diabetes (d = -0.17) and glomerulonephritis (d = -0.18) (p < 0.001), and lower proportions of indigenous people (d = -0.17, p < 0.001), current smokers (d = -0.10, p < 0.001), and people with prior histories of hemodialysis (d = -0.16, p < 0.001), diabetes mellitus (d = -0.18, p < 0.001), and coronary artery disease (d = -0.15, p < 0.001).

CONCLUSIONS

HONEYPOT trial participants tended to be healthier than the Australian and New Zealand PD patient population. Although the differences between the groups were generally modest, it is possible that their cumulative effect may have had some impact on external generalizability, which is not an uncommon occurrence in clinical trials.

The effect of pentoxifylline on oxidative stress in chronic kidney disease patients with erythropoiesis-stimulating agent hyporesponsiveness: Sub-study of the HERO trial

OBJECTIVE

Pentoxifylline has previously been shown to increase haemoglobin levels in patients with chronic kidney disease (CKD) and erythropoietin-stimulating agent (ESA)-hyporesponsive anaemia in the HERO multi-centre double-blind, randomized controlled trial. The present study evaluated the effects of pentoxifylline on oxidative stress in ESA-hyporesponsive CKD patients.

METHODS

This sub-study of the HERO trial compared 15 patients in the pentoxifylline arm (400 mg daily) and 17 in the matched placebo arm on oxidative stress markers: plasma total F2-isoprostanes, protein carbonyls, glutathione peroxidase (GPX), and superoxide dismutase (SOD) activities.

RESULTS

Pentoxifylline did not significantly alter total F2-isoprostanes (adjusted mean difference (MD) 35.01 pg/ml, P = 0.11), SOD activity (MD 0.82 U/ml, P = 0.07), GPX activity (MD -6.06 U/l, P = 0.09), or protein carbonyls (MD -0.04 nmol/mg, P = 0.52). Replicating results from the main study, pentoxifylline significantly increased haemoglobin concentration compared with controls (MD 7.2 g/l, P = 0.04).

CONCLUSIONS

Pentoxifylline did not alter oxidative stress biomarkers, suggesting that alternative mechanisms may be responsible for the agent's ability to augment haemoglobin levels in CKD patients with ESA-hyporesponsive anaemia.

The β-Blocker to Lower Cardiovascular Dialysis Events (BLOCADE) Feasibility Study: A Randomized Controlled Trial

BACKGROUND

β-Blocking agents reduce cardiovascular mortality in patients with heart disease, but their potential benefit in dialysis patients is unclear. We aimed to determine the feasibility of a randomized controlled trial (RCT).

STUDY DESIGN

Pilot RCT.

SETTING & PARTICIPANTS

Patients who received dialysis for 3 or more months and were 50 years or older (or ≥18 years with diabetes or cardiovascular disease) were recruited from 11 sites in Australia and New Zealand. We aimed to recruit 150 participants.

INTERVENTION

After a 6-week run-in with the β-blocker carvedilol, we randomly assigned participants to treatment with carvedilol or placebo for 12 months.

OUTCOMES & MEASUREMENTS

The prespecified primary outcome was the proportion of participants who tolerated carvedilol, 6.25mg, twice daily during the run-in period. After randomization, we report participant withdrawal and the incidence of intradialytic hypotension (IDH).

RESULTS

Of 1,443 patients screened, 354 were eligible, 91 consented, and 72 entered the run-in stage. 49 of 72 run-in participants (68%; 95% CI, 57%-79%) achieved the primary outcome. 5 of the 23 withdrawals from run-in were attributable to bradycardia or hypotension. After randomization, 10 of 26 allocated to carvedilol and 4 of 23 allocated to placebo withdrew. 4 participants randomly assigned to carvedilol withdrew because of bradycardia or hypotension. Overall, there were 4 IDH events per 100 hemodialysis sessions; in participants allocated to carvedilol versus placebo, respectively, there were 7 versus 2 IDH events per 100 hemodialysis sessions (P=0.1) in the 2 weeks immediately following a dose increase and 4 versus 3 IDH events per 100 hemodialysis sessions after no dose increase (P=0.7).

LIMITATIONS

Unable to recruit planned sample size.

CONCLUSIONS

Recruiting patients receiving dialysis to an RCT of β-blocker versus placebo will prove challenging. Possible solutions include international collaboration and exploring novel trial designs such as a registry-based RCT.

Association between serum alkaline phosphatase and primary resistance to erythropoiesis stimulating agents in chronic kidney disease: a secondary analysis of the HERO trial

BACKGROUND

Erythropoiesis stimulating agent (ESA)-resistant anemia is common in chronic kidney disease (CKD).

OBJECTIVES

To evaluate the determinants of severity of ESA resistance in patients with CKD and primary ESA-resistance.

DESIGN

Secondary analysis of a randomized controlled trial (the Handling Erythropoietin Resistance with Oxpentifylline, HERO).

SETTING AND PATIENTS

53 adult patients with CKD stage 4 or 5 and primary ESA-resistant anemia (hemoglobin ≤120 g/L, ESA resistance index [ERI] ≥1.0 IU/kg/week/gHb for erythropoietin or ≥0.005 μg/kg/week/gHb for darbepoeitin, no cause for ESA-resistance identified).

MEASUREMENTS

Iron studies, parathyroid hormone, albumin, liver enzymes, phosphate or markers of oxidative stress and inflammation.

METHODS

Participants were divided into tertiles of ERI. Multinomial logistic regression was used to analyse the determinants of ERI tertiles.

RESULTS

All patients, except one, were receiving dialysis for end-stage kidney disease. The mean ± SD ERI values in the low (n = 18), medium (n = 18) and high (n = 17) ERI tertiles were 1.4 ± 0.3, 2.3 ± 0.2 and 3.5 ± 0.8 IU/kg/week/gHb, respectively (P < 0.001). There were no significant differences observed in age, gender, ethnicity, cause of kidney disease, diabetes, iron studies, parathyroid hormone, albumin, liver enzymes, phosphate or markers of oxidative stress and inflammation between the ERI tertiles. The median [inter-quartile range] serum alkaline phosphatase concentrations in the low, medium and high ERI tertiles were 89 [64,121], 99 [76,134 and 148 [87,175] U/L, respectively (P = 0.054). There was a weak but statistically significant association between ERI and serum alkaline phosphatase (R(2) = 0.06, P = 0.03). Using multinomial logistic regression, the risk of being in the high ERI tertile relative to the low ERI tertile increased with increasing serum alkaline phosphatase levels (P = 0.02). No other variables were significantly associated with ERI.

LIMITATIONS

Small sample size; bone-specific alkaline phosphatase, other markers of bone turnover and bone biopsies not evaluated.

CONCLUSIONS

Serum alkaline phosphatase was associated with severity of ESA resistance in ESA-resistant patients with CKD. Large prospective studies are required to confirm this association. (

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry 12608000199314).

The Effect of Exit-Site Antibacterial Honey Versus Nasal Mupirocin Prophylaxis on the Microbiology and Outcomes of Peritoneal Dialysis-Associated Peritonitis and Exit-Site Infections: A Sub-Study of the Honeypot Trial

♦

BACKGROUND

The HONEYPOT study recently reported that daily exit-site application of antibacterial honey was not superior to nasal mupirocin prophylaxis for preventing overall peritoneal dialysis (PD)-related infection. This paper reports a secondary outcome analysis of the HONEYPOT study with respect to exit-site infection (ESI) and peritonitis microbiology, infectious hospitalization and technique failure. ♦

METHODS

A total of 371 PD patients were randomized to daily exit-site application of antibacterial honey plus usual exit-site care (N = 186) or intranasal mupirocin prophylaxis (in nasal Staphylococcus aureus carriers only) plus usual exit-site care (control, N = 185). Groups were compared on rates of organism-specific ESI and peritonitis, peritonitis- and infection-associated hospitalization, and technique failure (PD withdrawal). ♦

RESULTS

The mean peritonitis rates in the honey and control groups were 0.41 (95% confidence interval [CI] 0.32 - 0.50) and 0.41 (95% CI 0.33 - 0.49) episodes per patient-year, respectively (incidence rate ratio [IRR] 1.01, 95% CI 0.75 - 1.35). When specific causative organisms were examined, no differences were observed between the groups for gram-positive (IRR 0.99, 95% CI 0.66 - 1.49), gram-negative (IRR 0.71, 95% CI 0.39 - 1.29), culture-negative (IRR 2.01, 95% CI 0.91 - 4.42), or polymicrobial peritonitis (IRR 1.08, 95% CI 0.36 - 3.20). Exit-site infection rates were 0.37 (95% CI 0.28 - 0.45) and 0.33 (95% CI 0.26 - 0.40) episodes per patient-year for the honey and control groups, respectively (IRR 1.12, 95% CI 0.81 - 1.53). No significant differences were observed between the groups for gram-positive (IRR 1.10, 95% CI 0.70 - 1.72), gram-negative (IRR: 0.85, 95% CI 0.46 - 1.58), culture-negative (IRR 1.88, 95% CI 0.67 - 5.29), or polymicrobial ESI (IRR 1.00, 95% CI 0.40 - 2.54). Times to first peritonitis-associated and first infection-associated hospitalization were similar in the honey and control groups. The rates of technique failure (PD withdrawal) due to PD-related infection were not significantly different between the groups. ♦

CONCLUSION

Compared with standard nasal mupirocin prophylaxis, daily topical exit-site application of antibacterial honey resulted in comparable rates of organism-specific peritonitis and ESI, infection-associated hospitalization, and infection-associated technique failure in PD patients.

A randomized, placebo-controlled trial of pentoxifylline on erythropoiesis-stimulating agent hyporesponsiveness in anemic patients with CKD: the Handling Erythropoietin Resistance With Oxpentifylline (HERO) trial

BACKGROUND

Erythropoiesis-stimulating agent (ESA)-hyporesponsive anemia is common in chronic kidney disease (CKD). Pentoxifylline shows promise as a treatment for ESA-hyporesponsive anemia, but has not been rigorously evaluated.

STUDY DESIGN

Multicenter, double-blind, randomized, controlled trial.

SETTING & PARTICIPANTS

53 adult patients with CKD stage 4 or 5 (including dialysis) and ESA-hyporesponsive anemia (hemoglobin≤120g/L and ESA resistance index [calculated as weight-adjusted weekly ESA dose in IU/kg/wk divided by hemoglobin concentration in g/L]≥1.0IU/kg/wk/g/L for erythropoietin-treated patients and ≥0.005μg/kg/wk/g/L for darbepoetin-treated patients).

INTERVENTIONS

Pentoxifylline (400mg/d; n=26) or matching placebo (control; n=27) for 4 months.

OUTCOMES

PRIMARY OUTCOME

ESA resistance index at 4 months; secondary outcomes: hemoglobin concentration, ESA dose, blood transfusion requirement, serum ferritin level and transferrin saturation, C-reactive protein level, adverse events, quality of life, and health economics.

RESULTS

There was no statistically significant difference in ESA resistance index between the pentoxifylline and control groups (adjusted mean difference, -0.39 [95%CI, -0.89 to 0.10] IU/kg/wk/g/L; P=0.1). Pentoxifylline significantly increased hemoglobin concentration relative to the control group (adjusted mean difference, 7.6 [95%CI, 1.7-13.5] g/L; P=0.01). There was no difference in ESA dose between groups (-20.8 [95%CI, -67.2 to 25.7] IU/kg/wk; P=0.4). No differences in blood transfusion requirements, adverse events, or quality of life were observed between groups. Pentoxifylline cost A$88.05 (US $82.94) per person over the trial and produced mean savings in ESA cost of A$1,332 (US $1,255). The overall economic impact over the trial period was a saving of A$1,244 (US $1,172) per person for the pentoxifylline group compared with controls.

LIMITATIONS

Sample size smaller than planned due to slow recruitment.

CONCLUSIONS

Pentoxifylline did not significantly modify ESA hyporesponsiveness, but increased hemoglobin concentration. Further studies are warranted to determine whether pentoxifylline therapy represents a safe strategy for increasing hemoglobin levels in patients with CKD with ESA-hyporesponsive anemia.

Antibacterial honey for the prevention of peritoneal-dialysis-related infections (HONEYPOT): a randomised trial

BACKGROUND

There is a paucity of evidence to guide the best strategy for prevention of peritoneal-dialysis-related infections. Antibacterial honey has shown promise as a novel, cheap, effective, topical prophylactic agent without inducing microbial resistance. We therefore assessed whether daily application of honey at the exit site would increase the time to peritoneal-dialysis-related infections compared with standard exit-site care plus intranasal mupirocin prophylaxis for nasal carriers of Staphylococcus aureus.

METHODS

In this open-label trial undertaken in 26 centres in Australia and New Zealand, participants undergoing peritoneal dialysis were randomly assigned in a 1:1 ratio with an adaptive allocation algorithm to daily topical exit-site application of antibacterial honey plus standard exit-site care or intranasal mupirocin prophylaxis (only in carriers of nasal S aureus) plus standard exit-site care (control group). The primary endpoint was time to first infection related to peritoneal dialysis (exit-site infection, tunnel infection, or peritonitis). The trial is registered with the Australian New Zealand Clinical Trials Registry, number 12607000537459.

FINDINGS

Of 371 participants, 186 were assigned to the honey group and 185 to the control group. The median peritoneal-dialysis-related infection-free survival times were not significantly different in the honey (16·0 months [IQR not estimable]) and control groups (17·7 months [not estimable]; unadjusted hazard ratio 1·12, 95% CI 0·83-1·51; p=0·47). In the subgroup analyses, honey increased the risks of both the primary endpoint (1·85, 1·05-3·24; p=0·03) and peritonitis (2·25, 1·16-4·36) in participants with diabetes. The incidences of serious adverse events (298 vs 327, respectively; p=0·1) and deaths (14 vs 18, respectively; p=0·9) were not significantly different in the honey and control groups. 11 (6%) participants in the honey group had local skin reactions.

INTERPRETATION

The findings of this trial show that honey cannot be recommended routinely for the prevention of peritoneal-dialysis-related infections.

FUNDING

Baxter Healthcare, Queensland Government, Comvita, and Gambro.

Toxicity and detoxification of lipid-derived aldehydes in cultured retinal pigmented epithelial cells

Age-related macular degeneration (ARMD) is the leading cause of blindness in the developed world and yet its pathogenesis remains poorly understood. Retina has high levels of polyunsaturated fatty acids (PUFAs) and functions under conditions of oxidative stress. To investigate whether peroxidative products of PUFAs induce apoptosis in retinal pigmented epithelial (RPE) cells and possibly contribute to ARMD, human retinal pigmented epithelial cells (ARPE-19) were exposed to micromolar concentrations of H2O2, 4-hydroxynonenal (HNE) and 4-hydroxyhexenal (HHE). A concentration- and time-dependent increase in H2O2-, HNE-, and HHE-induced apoptosis was observed when monitored by quantifying DNA fragmentation as determined by ELISA, flow cytometry, and Hoechst staining. The broad-spectrum inhibitor of apoptosis Z-VAD inhibited apoptosis. Treatment of RPE cells with a thionein peptide prior to exposure to H2O2 or HNE reduced the formation of protein-HNE adducts as well as alteration in mitochondrial membrane potential and apoptosis. Using 3H-HNE, various metabolic pathways to detoxify HNE by ARPE-19 cells were studied. The metabolites were separated by HPLC and characterized by ElectroSpray Ionization-Mass Spectrometry (ESI-MS) and gas chromatography-MS. Three main metabolic routes of HNE detoxification were detected: (1) conjugation with glutathione (GSH) to form GS-HNE, catalyzed by glutathione-S-transferase (GST), (2) reduction of GS-HNE catalyzed by aldose reductase, and (3) oxidation of HNE catalyzed by aldehyde dehydrogenase (ALDH). Preventing HNE formation by a combined strategy of antioxidants, scavenging HNE by thionein peptide, and inhibiting apoptosis by caspase inhibitors may offer a potential therapy to limit retinal degeneration in ARMD.

Discovery of estrogen receptor alpha target genes and response elements in breast tumor cells

Microarray analysis has identified 89 estrogen target genes. The cis-regulatory elements found upstream of those genes are not well conserved in mouse and human.

Background

Estrogens and their receptors are important in human development, physiology and disease. In this study, we utilized an integrated genome-wide molecular and computational approach to characterize the interaction between the activated estrogen receptor (ER) and the regulatory elements of candidate target genes.

Results

Of around 19,000 genes surveyed in this study, we observed 137 ER-regulated genes in T-47D cells, of which only 89 were direct target genes. Meta-analysis of heterogeneous in vitro and in vivo datasets showed that the expression profiles in T-47D and MCF-7 cells are remarkably similar and overlap with genes differentially expressed between ER-positive and ER-negative tumors. Computational analysis revealed a significant enrichment of putative estrogen response elements (EREs) in the cis-regulatory regions of direct target genes. Chromatin immunoprecipitation confirmed ligand-dependent ER binding at the computationally predicted EREs in our highest ranked ER direct target genes, NRIP1, GREB1 and ABCA3. Wider examination of the cis-regulatory regions flanking the transcriptional start sites showed species conservation in mouse-human comparisons in only 6% of predicted EREs.

Conclusions

Only a small core set of human genes, validated across experimental systems and closely associated with ER status in breast tumors, appear to be sufficient to induce ER effects in breast cancer cells. That cis-regulatory regions of these core ER target genes are poorly conserved suggests that different evolutionary mechanisms are operative at transcriptional control elements than at coding regions. These results predict that certain biological effects of estrogen signaling will differ between mouse and human to a larger extent than previously thought.

Isolated epithelial cells from amphibian urinary bladder express functional gap junctional hemichannels

Exposure of the urinary bladder epithelium of Necturus maculosus (NUB) to protease and collagenase yields approximately 50% isolated polarized cells. These cells express a membrane current slowly activated by depolarization or by removal of external divalent cations. The biophysical and pharmacological properties of the current are largely consistent with those of gap junctional hemichannels. After removal of divalent cations, the cells can also be loaded with 5(6)-carboxyfluorescein, a hydrophilic fluorescent anionic dye, and exposure to dye reduces the current in a manner dependent on membrane voltage and side of application. In contrast, Necturus gallbladder (NGB) cells exhibit no membrane conductance attributable to gap junctional hemichannels, although previous studies reveal the persistence of gap junction plaques on the plasma membrane. We conclude that functional gap junctional hemichannels can be expressed on the surface of certain isolated epithelial cells and that this is not a necessary consequence of the isolation procedure. These structures may contribute to cell damage under pathological conditions involving cell detachment.

Dependence of intracellular signaling and neurosecretion on phospholipase D activation in immortalized gonadotropin-releasing hormone neurons

The excitability of gonadotropin-releasing hormone (GnRH) neurons is essential for episodic neuropeptide release, but the mechanism by which electrical activity controls GnRH secretion is not well characterized. The role of phospholipase D (PLD) in mediating the activity-dependent secretory pathway was investigated in immortalized GT1 neurons, which both secrete GnRH and express GnRH receptors. Activation of these Ca2+-mobilizing receptors was associated with transient hyperpolarization of GT1 cells, followed by sustained firing of action potentials. This was accompanied by an increase in PLD activity, as indicated by elevated phosphatidylethanol (PEt) production. GnRH-induced PEt production was reduced by inhibition of phospholipase C-dependent phosphoinositide hydrolysis by U73122 and neomycin, suggesting that signaling from phospholipase C led to activation of PLD. The intermediate role of protein kinase C (PKC) in this process was indicated by the ability of phorbol 12-myristate 13-acetate to induce time- and dose-dependent increases in PEt and diacylglycerol, but not inositol trisphosphate, and by reduction of GnRH-induced PEt accumulation in PKC-depleted cells. Consistent with the role of action potential-driven Ca2+ entry in this process, agonist-induced PLD activity was also reduced by nifedipine and low extracellular Ca2+. Inhibition of the PLD pathway by ethanol and propranolol reduced diacylglycerol production and caused a concomitant fall in GnRH release. These data indicate that voltage-gated Ca2+ entry and PKC act in an independent but cooperative manner to regulate PLD activity, which contributes to the secretory response in GT1 cells. Thus, the electrical activity of the GnRH-secreting neuron participates in the functional coupling between GnRH receptors and PLD pathway.

Expression of purinergic receptor channels and their role in calcium signaling and hormone release in pituitary gonadotrophs. Integration of P2 channels in plasma membrane- and endoplasmic reticulum-derived calcium oscillations

The role of ATP as a positive feedback element in Ca2+ signaling and secretion was examined in female rat pituitary gonadotrophs. ATP and ADP, but not AMP or adenosine, induced a dose- and extracellular Ca2+-dependent rise in [Ca2+]i in identified gonadotrophs in a Mg2+- and suramin-sensitive manner. ATP, adenosine-5'-O-(3-thiotriphosphate), adenosine-5'-O-(1-thiotriphosphate), 2-methylthio-ATP, and 3'-O-(4-benzoyl)benzoyl-ATP were roughly equipotent in rising [Ca2+]i in gonadotrophs, while ADP was effective only at submillimolar concentration range, and none of these compounds permeabilized the cells. On the other hand, alpha,beta-methylene-ATP, beta,gamma-methylene-ATP, and UTP were unable to induce any rise in [Ca2+]i. This pharmacological profile is consistent with expression of P2X2 and/or P2X5 purinergic receptor channels. Patch-clamp experiments showed that ATP induced an inward depolarizing current in gonadotrophs clamped at -90 mV, associated with an increase in [Ca2+]i. The ATP-induced [Ca2+]i response was partially inhibited by nifedipine, a blocker of voltage-sensitive Ca2+ channels (VSCC), but was not affected by tetrodotoxin, a blocker of voltage-sensitive Na+ channels. Thus, the P2-depolarizing current itself drives Ca2+ into the cell, but also activates Ca2+ entry through VSCC. In accord with this, low [ATP] induced plasma membrane-dependent [Ca2+]i oscillations in quiescent cells, and increased the frequency of spiking in spontaneously active cells. ATP-induced Ca2+ influx also affected agonist-induced and InsP3-dependent [Ca2+]i oscillations by increasing the frequency, base line, and duration of Ca2+ spiking. In addition, ATP stimulated gonadotropin secretion and enhanced agonist-induced gonadotropin release. ATP was found to be secreted by pituitary cells during agonist stimulation and was promptly degraded by ectonucleotidase to adenosine. These observations indicate that ATP represents a paracrine/autocrine factor in the regulation of Ca2+ signaling and secretion in gonadotrophs, and that these actions are mediated by P2 receptor channels.

GnRH-induced cytosolic calcium oscillations in pituitary gonadotrophs: phase resetting by membrane depolarization

Cultured rat pituitary gonadotrophs under whole-cell voltage clamp conditions respond to the hypothalamic hormone GnRH with synchronized oscillatory changes in both cytosolic Ca2+ concentration ([Ca2+]i) and [Ca2+]i-activated, apamin-sensitive K+ current (IK(Ca)). We found, and report here for the first time, that in GnRH-stimulated cells a brief depolarizing pulse can elicit a transient [Ca2+]i rise similar to the endogenous cycle. Furthermore, Ca2+ entry during a single depolarizing pulse was found to shift the phase of subsequent endogenous [Ca2+]i oscillations, which thereafter continue to occur at their previous frequency before the pulse. Application of two consecutive depolarizing pulses showed that the size of the [Ca2+]i rise evoked by the second pulse depended on the time lapsed between two consecutive pulses, indicating that each endogenous or evoked [Ca2+]i rise cycle leaves the Ca2+ release mechanism of the gonadotroph in a refractory state. Recovery from this condition can be described by an exponential function of the time lapsed between the pulses (time constant of ca. 1 s). We propose that the underlying mechanism in both refractoriness after endogenous cycles and phase resetting by a brief pulse of Ca2+ entry involves the InsP3 receptor-channel molecule presumed to be located on the cytosolic aspect of the endoplasmic reticulum membrane.

Inhibitory effect of strychnine on acetylcholine receptor activation in bovine adrenal medullary chromaffin cells

1. Strychnine, which is known as a potent and selective antagonist of the inhibitory glycine receptor in the central nervous system, inhibits the nicotinic stimulation of catecholamine release from bovine cultured adrenal chromaffin cells in a concentration-dependent (1-100 microM) manner. At 10 microM nicotine, the IC50 value for strychnine is approximately 30 microM. Strychnine also inhibits the nicotine-induced membrane depolarization and increase in intracellular Ca2+ concentration. 2. The inhibitory action of strychnine is reversible and is selective for nicotinic stimulation, with no effect observed on secretion elicited by a high external K+ concentration, histamine or angiotensin II. 3. Strychnine competes with nicotine in its effect, but not modify the apparent positive cooperatively of the nicotine binding sites. In the absence of nicotine, strychnine has no effect on catecholamine release. Glycine does not affect catecholamine release nor the inhibitory action of strychnine on this release. 4. These results suggest that strychnine interacts with the agonist binding site of the nicotinic acetylcholine receptor in chromaffin cells, thus exerting a pharmacological effect independently of the glycine receptor.