Publications by authors named "Linda McCann"

22 Publications

  • Page 1 of 1

Asymmetry of marine invasions across tropical oceans.

Ecology 2021 08 14;102(8):e03434. Epub 2021 Jul 14.

Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, Maryland, 21037, USA.

Understanding the mechanisms of spatial variation of biological invasions, across local-to-global scales, has been a major challenge. The importance of evolutionary history for invasion dynamics was noted by Darwin, and several studies have since considered how biodiversity of source and recipient regions can influence the probability of invasions. For over a century, the Panama Canal has connected water bodies and biotas with different evolutionary histories, and created a global shipping hot spot, providing unique opportunities to test mechanisms that affect invasion patterns. Here, we test for asymmetry in both the extent of invasions and predation effects, a possible mechanism of biotic resistance, between two tropical oceans at similar latitudes. We estimated nonnative species (NNS) richness for sessile marine invertebrates, using standardized field surveys and literature synthesis, to examine whether invasions are asymmetrical, with more NNS present in the less diverse Pacific compared to the Atlantic. We also experimentally tested whether predation differentially limits the abundance and distribution of these invertebrates between oceans. In standardized surveys, observed total NNS richness was higher in the Pacific (18 NNS, 30% of all Pacific species) than the Atlantic (11 NNS, 13% of all Atlantic species). Similarly, literature-based records also display this asymmetry between coasts. When considering only the reciprocal exchange of NNS between Atlantic and Pacific biotas, NNS exchange from Atlantic to Pacific was eightfold higher than the opposite direction, exceeding the asymmetry predicted by random exchange based simply on differences of overall diversity per region. Predation substantially reduced biomass and changed NNS composition in the Pacific, but no such effects were detected on the Atlantic coast. Specifically, some dominant NNS were particularly susceptible to predation in the Pacific, supporting the hypothesis that predation may reduce the abundance of certain NNS here. These results are consistent with predictions that high diversity in source regions, and species interactions in recipient regions, shape marine invasion patterns. Our comparisons and experiments across two tropical ocean basins, suggest that global invasion dynamics are likely driven by both ecological and evolutionary factors that shape susceptibility to and directionality of invasions across biogeographic scales.
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http://dx.doi.org/10.1002/ecy.3434DOI Listing
August 2021

Stage-specific overcompensation, the hydra effect, and the failure to eradicate an invasive predator.

Proc Natl Acad Sci U S A 2021 03;118(12)

Woods Hole Oceanographic Institution, Woods Hole, MA 02543.

As biological invasions continue to increase globally, eradication programs have been undertaken at significant cost, often without consideration of relevant ecological theory. Theoretical fisheries models have shown that harvest can actually increase the equilibrium size of a population, and uncontrolled studies and anecdotal reports have documented population increases in response to invasive species removal (akin to fisheries harvest). Both findings may be driven by high levels of juvenile survival associated with low adult abundance, often referred to as overcompensation. Here we show that in a coastal marine ecosystem, an eradication program resulted in stage-specific overcompensation and a 30-fold, single-year increase in the population of an introduced predator. Data collected concurrently from four adjacent regional bays without eradication efforts showed no similar population increase, indicating a local and not a regional increase. Specifically, the eradication program had inadvertently reduced the control of recruitment by adults via cannibalism, thereby facilitating the population explosion. Mesocosm experiments confirmed that adult cannibalism of recruits was size-dependent and could control recruitment. Genomic data show substantial isolation of this population and implicate internal population dynamics for the increase, rather than recruitment from other locations. More broadly, this controlled experimental demonstration of stage-specific overcompensation in an aquatic system provides an important cautionary message for eradication efforts of species with limited connectivity and similar life histories.
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http://dx.doi.org/10.1073/pnas.2003955118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8000505PMC
March 2021

Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder: Synopsis of the Kidney Disease: Improving Global Outcomes 2017 Clinical Practice Guideline Update.

Ann Intern Med 2018 03 20;168(6):422-430. Epub 2018 Feb 20.

Stanford University School of Medicine, Stanford, California (M.B.L.).

Description: The Kidney Disease: Improving Global Outcomes (KDIGO) 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) is a selective update of the prior CKD-MBD guideline published in 2009. The guideline update and the original publication are intended to assist practitioners caring for adults with CKD and those receiving long-term dialysis.

Methods: Development of the guideline update followed an explicit process of evidence review and appraisal. The approach adopted by the Work Group and the evidence review team was based on systematic reviews of relevant trials, appraisal of the quality of the evidence, and rating of the strength of recommendations according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. Searches of the English-language literature were conducted through September 2015 and were supplemented with targeted searches through February 2017. Final modification of the guidelines was informed by a public review process involving numerous stakeholders, including patients, subject matter experts, and industry and national organizations.

Recommendations: The update process resulted in the revision of 15 recommendations. This synopsis focuses primarily on recommendations for diagnosis of and testing for CKD-MBD and treatment of CKD-MBD that emphasizes decreasing phosphate levels, maintaining calcium levels, and addressing elevated parathyroid hormone levels in adults with CKD stage G3a to G5 and those receiving dialysis. Key elements include basing treatment on trends in laboratory values rather than a single abnormal result and being cautious to avoid hypercalcemia when treating secondary hyperparathyroidism.
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http://dx.doi.org/10.7326/M17-2640DOI Listing
March 2018

Executive summary of the 2017 KDIGO Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) Guideline Update: what's changed and why it matters.

Kidney Int 2017 07;92(1):26-36

Stanford University School of Medicine, Stanford, California, USA. Electronic address:

The KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of CKD-MBD represents a selective update of the prior CKD-MBD Guideline published in 2009. This update, along with the 2009 publication, is intended to assist the practitioner caring for adults and children with chronic kidney disease (CKD), those on chronic dialysis therapy, or individuals with a kidney transplant. This review highlights key aspects of the 2017 CKD-MBD Guideline Update, with an emphasis on the rationale for the changes made to the original guideline document. Topic areas encompassing updated recommendations include diagnosis of bone abnormalities in CKD-mineral and bone disorder (MBD), treatment of CKD-MBD by targeting phosphate lowering and calcium maintenance, treatment of abnormalities in parathyroid hormone in CKD-MBD, treatment of bone abnormalities by antiresorptives and other osteoporosis therapies, and evaluation and treatment of kidney transplant bone disease.
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http://dx.doi.org/10.1016/j.kint.2017.04.006DOI Listing
July 2017

Evaluating the combined effects of ballast water management and trade dynamics on transfers of marine organisms by ships.

PLoS One 2017 20;12(3):e0172468. Epub 2017 Mar 20.

Marine Invasions Research Laboratory, Smithsonian Environmental Research Center, Edgewater, Maryland, United States of America.

Global trade by merchant ships is a leading mechanism for the unintentional transfer of marine organisms, including non-indigenous species, to bays and estuaries worldwide. To reduce the likelihood of new invasions, ships are increasingly being required to manage their ballast water (BW) prior to discharge in coastal waters. In the United States, most overseas arrivals have been required to manage BW discharge since 2004, primarily through ballast water exchange (BWE), which flushes out ballast tanks in the open ocean (>200 miles from shore). Studies have found BWE to generally reduce the abundance of organisms, and the amount of water exchanged has been estimated at 96-100%. Despite its widespread use, the overall effect of this management strategy on net propagule supply through time has not been explored. Here, temporal changes in zooplankton concentrations and the volume of BW discharged in Chesapeake Bay, U.S. were evaluated, comparing pre-management era and post-management era time periods. Chesapeake Bay is a large port system that receives extensive BW discharge, especially from bulk cargo vessels (bulkers) that export coal overseas. For bulkers arriving from overseas, mean zooplankton concentrations of total and coastal indicator taxa in BW did not decline between pre- (1993-2000) and post management (2012-2013) eras, when controlling for season and sampling method. Moreover, bulkers discharged 21 million tonnes (82% of total for Chesapeake Bay) of overseas BW in 2013, representing a 374% increase in volume when compared to 2005. The combination of BW discharge volume and zooplankton concentration data indicates that (a) net propagule supply by bulkers has increased since BWE began in Chesapeake Bay; and (b) changes in vessel behaviour and trade have contributed strongly to this outcome. Specifically, the coal-driven increase in BW discharge volume from 2005-2013, concurrent with the onset of BWE regulations, worked to counteract intended results from BW management. A long-term analysis of bulker arrivals (1994-2013) reveals a 20-year minimum in arrival numbers in 2000, just when the implementation of BWE began. This study underscores the need to consider shifts in trade patterns, in order to advance and evaluate effective management strategies for biological invasions.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172468PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5358743PMC
August 2017

Academy of Nutrition and Dietetics and National Kidney Foundation: revised 2014 standards of practice and standards of professional performance for registered dietitian nutritionists (competent, proficient, and expert) in nephrology nutrition.

J Acad Nutr Diet 2014 Sep;114(9):1448-1457.e45

Compelling evidence indicates that the incidence of chronic kidney disease (CKD) is increasing because of an aging population and a higher prevalence of cardiovascular disease, diabetes, and hypertension. Nutrition management of patients with CKD requires early disease recognition, appropriate interpretation of the markers and stages of CKD, and collaboration with other health care practitioners. Better management of CKD can slow its progression, prevent metabolic complications, and reduce cardiovascular related outcomes. Caring for patients with CKD necessitates specialized knowledge and skills to meet the challenges associated with this growing epidemic. The Academy of Nutrition and Dietetics Renal Dietitians Practice Group and the National Kidney Foundation Council on Renal Nutrition, with guidance from the Academy of Nutrition and Dietetics Quality Management Committee, have updated the 2009 Standards of Practice in Nutrition Care and Standards of Professional Performance as a tool for registered dietitian nutritionists working in nephrology nutrition to assess their current skill levels and to identify areas for additional professional development in this practice area. The Standards of Practice apply to the care of patients/clients with kidney disease. The Standards of Professional Performance consist of six domains of professionalism, including: Quality in Practice, Competence and Accountability, Provision of Services, Application of Research, Communication and Application of Knowledge, and Utilization and Management of Resources. Within each standard, specific indicators provide measurable action statements that illustrate how nephrology nutrition principles can be applied to practice. The indicators describe three skill levels (ie, competent, proficient, and expert) for registered dietitian nutritionists working in nephrology nutrition.
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http://dx.doi.org/10.1016/j.jand.2014.05.006DOI Listing
September 2014

Academy of Nutrition and Dietetics and National Kidney Foundation: revised 2014 Standards of Practice and Standards of Professional Performance for registered dietitian nutritionists (competent, proficient, and expert) in nephrology nutrition.

J Ren Nutr 2014 Sep;24(5):275-285.e45

Clinical Support, DaVita HealthCare Partners, Yorba Linda, California.

Compelling evidence indicates that the incidence of chronic kidney disease (CKD) is increasing because of an aging population and a higher prevalence of cardiovascular disease, diabetes, and hypertension. Nutrition management of patients with CKD requires early disease recognition, appropriate interpretation of the markers and stages of CKD, and collaboration with other health care practitioners. Better management of CKD can slow its progression, prevent metabolic complications, and reduce cardiovascular related outcomes. Caring for patients with CKD necessitates specialized knowledge and skills to meet the challenges associated with this growing epidemic. The Academy of Nutrition and Dietetics Renal Dietitians Practice Group and the National Kidney Foundation Council on Renal Nutrition, with guidance from the Academy of Nutrition and Dietetics Quality Management Committee, have updated the 2009 Standards of Practice in Nutrition Care and Standards of Professional Performance as a tool for registered dietitian nutritionists working in nephrology nutrition to assess their current skill levels and to identify areas for additional professional development in this practice area. The Standards of Practice apply to the care of patients/clients with kidney disease. The Standards of Professional Performance consist of six domains of professionalism, including: Quality in Practice, Competence and Accountability, Provision of Services, Application of Research, Communication and Application of Knowledge, and Utilization and Management of Resources. Within each standard, specific indicators provide measurable action statements that illustrate how nephrology nutrition principles can be applied to practice. The indicators describe three skill levels (ie, competent, proficient, and expert) for registered dietitian nutritionists working in nephrology nutrition.
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http://dx.doi.org/10.1053/j.jrn.2014.05.008DOI Listing
September 2014

Multidisciplinary team care for CKD-MBD. Achieving KDIGO guideline recommendations in the bundling era.

Nephrol News Issues 2014 Apr;28(4):24-6, 28, 30-2 passim

The increasing prevalence of end-stage renal disease and planned expansion of the Medicare bundled payment system will place a greater financial burden on dialysis providers. Management of chronic kidney disease mineral and bone disorder (CKD-MBD) is dependent on interdisciplinary team (IDT) interventions such as dietary modification, medication, and adequate dialysis therapy. Optimizing adherence to diet and medications requires an educated and motivated IDT, patient, and patient support system. The financial constraints of bundling will increase the roles of social workers and dietitians in promoting therapy adherence. Innovative and relevant tactics provide opportunity to overcome monotonous routines, encourage adherence to diet and complex polypharmacy regimens, and achieve recommended biochemical targets as outlined in Kidney Disease Improving Global Outcomes Guideline for Chronic Kidney Disease (KDIGO) - CKD-MBD.
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April 2014

Promoting invasive species control and eradication in the sea: options for managing the tunicate invader Didemnum vexillum in Sitka, Alaska.

Mar Pollut Bull 2013 Dec;77(1-2):165-71

Bioinvasions are a significant force of change--and economic and ecological threat--in marine ecosystems. The threat now encroaches on Alaska, which has had relatively few invasions compared to other global regions, prompting need to develop new incursion response tools. We appraised five 'eco-friendly' immersion treatment options (dilute acetic acid, dilute bleach, freshwater, brine and hypoxia) at either minute- or hour-scale exposures to kill the invasive tunicate Didemnum vexillum. Data revealed 100% treatment efficacy after two minutes in acetic acid, ten minutes in bleach, four hours in freshwater and over four hours in brine solution. We also demonstrated the importance of monitoring D. vexillum recovery for at least three weeks, since seemingly destroyed colonies rebounded during this timeframe. Combined, these findings provide insights towards a bay-scale eradication and post-border management plan applicable to the recent D. vexillum incursion in Whiting Harbor, Alaska and other shallow, inshore invasion sites.
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http://dx.doi.org/10.1016/j.marpolbul.2013.10.011DOI Listing
December 2013

Roles of calcium-sensing receptor and vitamin d receptor in the pathophysiology of secondary hyperparathyroidism.

J Ren Nutr 2010 May 19;20(3):141-50. Epub 2010 Mar 19.

Dialysis Division, Satellite Healthcare, Mountain View, California, USA.

The calcium-sensing receptor (CaR) and the vitamin D receptor (VDR) play key roles in calcium homeostasis. The CaR regulates the release of parathyroid hormone (PTH) in response to changes in extracellular calcium, whereas the VDR mediates the effects of calcitriol, the active metabolite of vitamin D. The development of secondary hyperparathyroidism (HPT) is a common complication of chronic kidney disease. Secondary HPT is characterized by disturbances in mineral metabolism, elevated serum PTH, and parathyroid gland hyperplasia. Alterations in CaR and VDR expression and activation play central roles in the development of secondary HPT. The impact of any nutritional and pharmacologic intervention on these two receptors should be carefully considered, to optimize patient outcomes. The important roles of CaR and VDR in the pathogenesis of secondary HPT are demonstrated by the complex interactions between their respective signaling pathways.
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http://dx.doi.org/10.1053/j.jrn.2010.01.004DOI Listing
May 2010

American Dietetic Association and the National Kidney Foundation Standards of Practice and Standards of Professional Performance for registered dietitians (generalist, specialty, and advanced) in nephrology care.

J Ren Nutr 2009 Sep;19(5):345-56

The American Dietetic Association (ADA) Renal Dietitians Practice Group (RPG) and the National Kidney Foundation Council on Renal Nutrition (NKF CRN), under the guidance of the ADA Quality Management Committee and Scope of Dietetics Practice Framework Sub-Committee, have developed the Standards of Practice (SOP) and Standards of Professional Performance (SOPP) for Registered Dietitians (Generalist, Specialty, and Advanced) in Nephrology Care (Supplementary Figures 1, 2, and 3 are available only online at www.jrnjournal.org). The SOP and SOPP documents are based upon the 2008 Revised Standards of Practice in Nutrition Care and Standards of Professional Performance for Registered Dietitians (RDs)(1), which are part of ADA's Scope of Dietetics Practice Framework(2). The 2008 Revised SOP in Nutrition Care and SOPP, along with the Code of Ethics(3), guide the practice and performance of RDs in all settings.
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http://dx.doi.org/10.1053/j.jrn.2009.06.020DOI Listing
September 2009

Interrupting a multi-species bioinvasion vector: the efficacy of in-water cleaning for removing biofouling on obsolete vessels.

Mar Pollut Bull 2008 Sep 18;56(9):1538-44. Epub 2008 Jul 18.

Aquatic Bioinvasion Research and Policy Institute, Portland State University, Portland, OR 97207-0751, USA.

Vector management is the primary method for reducing and preventing nonindigenous species (NIS) invasions and their ecological and economic consequences. This study was the first to examine the efficacy of in-water scrubbing using a submersible cleaning and maintenance platform (SCAMP) to prevent invertebrate species transfers from a heavily fouled obsolete vessel. Initially, prior to treatment, 37 species were recorded in a biofouling matrix that reached 30cm depth in some locations. The bryozoan Conopeum chesapeakensis, and bivalves Mytilopsis leucophaeata and Ischadium recurvum, were dominant sessile species that created structure, supporting mobile biota that included crabs and the associated parasitic barnacle Loxothylacus panopae. Scrubbing had the effect of significantly reducing organism extent and the number of species per sample, but a substantial and diverse (30 species) residual fouling community remained across the entire vessel. Further assessments of management options are needed to prevent potentially damaging NIS transfers. Additional measures taken within an integrated vector management (IVM) strategy may further improve invasion prevention measures.
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http://dx.doi.org/10.1016/j.marpolbul.2008.05.024DOI Listing
September 2008

Multicenter study of the validity and reliability of subjective global assessment in the hemodialysis population.

J Ren Nutr 2007 Sep;17(5):336-42

Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106-4954, USA.

Objective: Subjective Global Assessment (SGA) is a nutrition assessment tool recommended by the 2000 NKF K/DOQI Nutrition Guidelines. However, the validity and reliability of this tool have not been established in hemodialysis (HD) patients. The purpose of this observational study was to determine the reliability and validity of SGA in the HD population. Renal dietitians (RD) were recruited to perform SGA (7-point scale version) and collect data on demographics, clinical status, biochemistries, dietary intake, and quality of life (Medical Outcomes Short Form-36) on 3 HD patients at baseline and 6 months later.

Design: The 54 participating RDs were trained to perform SGA and collect data via a website created for this study. Interrater reliability for SGA was tested in a subset of 76 patients, via an SGA performed by a second RD at baseline, while intrarater reliability was assessed by the original RD repeating the SGA at 1 month. Data collection occurred at HD facilities in the United States (109 patients), Canada (35 patients), and New Zealand (9 patients).

Results: Of the 153 patients, 46% were female, 64% were Caucasian, 6% were Hispanic, 21% were African American, and 6% were Asian. The primary etiologies were hypertension (33%), type 2 diabetes mellitus (DM) (27%), type 1 DM (10%), and glomerular nephritis (10%); 59% had cardiovascular disease. The mean age, body mass index (BMI), serum albumin, and duration on HD were 64 +/- 14 years (mean +/- SD), 28 +/- 7 kg/m(2), 3.7 +/- 0.4 mg/dL, and 41 +/- 34 months, respectively. SGA scores were well nourished (7)-30%; mildly malnourished (MN 6)-41%; moderately MN 5-21%, 4-7%, and 3-2%; and severely MN (2 and 1)-0%. SGA training via the Internet achieved fair interrater reliability (weighted Kappa = 0.5, Spearman's Rho = 0.7) and substantial intrarater reliability (weighted Kappa = 0.7, Spearman's Rho = 0.8) (P < .001). Validity was demonstrated through statistically significant differences in mean BMI and serum albumin across the 5 categories of SGA (7-28 +/- 7, 6-29 +/- 7, 5-28 +/- 8, 4-21 +/- 4, 3-24 +/- 2, P < .05; and 7-3.8 +/- 0.3, 6-3.8 +/- 0.4, 5-37 +/- 0.05, 4-3.4 +/- 0.07, 3-2.9 +/- 1.2, P < .001, respectively). Nutritional status varied by age (P < .05), but not ethnicity or nationality.

Conclusion: We conclude that the 7-point scale SGA is a reliable and valid tool for nutritional assessment in adults on HD.
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http://dx.doi.org/10.1053/j.jrn.2007.05.004DOI Listing
September 2007

Calcium in chronic kidney disease: recommended intake and serum targets.

Authors:
Linda McCann

Adv Chronic Kidney Dis 2007 Jan;14(1):75-8

Satellite Healthcare, Inc, Mountain View, CA 94041, USA.

Abnormal mineral metabolism has the potential to significantly increase mortality in patients with chronic kidney disease, especially by the time renal replacement therapy is required. While excess phosphorus and hyperphosphatemia have long been identified as risks for increased morbidity and mortality, the roles of calcium load and serum calcium levels have been less clear. Calcium-based recommendations in the K/DOQI Clinical Practice Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease were labeled as expert opinion. The rationale behind the opinion-based recommendations is reviewed along with additional supportive information that has become available since the bone and mineral guidelines were published.
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http://dx.doi.org/10.1053/j.ackd.2006.10.011DOI Listing
January 2007

Subjective Global Assessment in chronic kidney disease: a review.

J Ren Nutr 2004 Oct;14(4):191-200

Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106, USA.

Nutritional assessment of patients with chronic kidney disease is a vital function of health care providers. Subjective Global Assessment (SGA) is a tool that uses 5 components of a medical history (weight change, dietary intake, gastrointestinal symptoms, functional capacity, disease and its relation to nutritional requirements) and 3 components of a brief physical examination (signs of fat and muscle wasting, nutrition-associated alternations in fluid balance) to assess nutritional status. SGA was originally used to predict outcomes in surgical patients; however, its use has gone beyond this function and population. In chronic kidney disease patients, SGA is incorporated into the complete nutritional assessment. Validation of SGA as a screening tool for surgical patients was done by Detsky et al in 1984. Since that time, SGA has been altered by different researchers and clinicians to better meet the needs of the patients they served. Validation of the altered SGA formats has not been thoroughly done. Further work in establishing validity and reliability of each version of SGA in different patient populations should be done to enable clinicians and researchers to properly use this nutritional assessment tool.
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October 2004

Randomized trial of folic acid for prevention of cardiovascular events in end-stage renal disease.

J Am Soc Nephrol 2004 Feb;15(2):420-6

Satellite Research, Redwood City, California 94598, USA.

High serum total homocysteine (tHcy) is gaining scrutiny as a risk factor for cardiovascular disease in the general population. The relationship between tHcy and mortality and cardiovascular events in patients with end-stage renal disease (ESRD) is unsettled. This randomized trial evaluates the efficacy of high-dose folic acid in preventing events in ESRD. A total of 510 patients on chronic dialysis were randomized to 1, 5, or 15 mg of folic acid contained in a renal multivitamin with a median follow-up of 24 mo. Mortality, cardiovascular events, and homocysteine levels were assessed. There were 189 deaths, and 121 patients experienced at least one cardiovascular event. Composite rates of mortality and cardiovascular events among the folic acid groups did not differ (at 24 mo: 43.7% in 1 mg group, 38.6% in 5 mg group, 47.1% in 15 mg group; log-rank P = 0.47). Unexpectedly, high baseline tHcy was associated with lower event rates. From lowest to highest quartile, event rates at 24 mo were 54.5% for Q1, 41.8% for Q2, 41.2% for Q3, and 34.7% for Q4 (log-rank P = 0.033). In contrast to some studies describing tHcy as a risk factor for mortality and cardiovascular events, this study found a reverse relationship between tHcy and events in ESRD patients. Administration of high-dose folic acid did not affect event rates.
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http://dx.doi.org/10.1097/01.asn.0000110181.64655.6cDOI Listing
February 2004

A comparison of dual dialyzers in parallel and series to improve urea clearance in large hemodialysis patients.

Am J Kidney Dis 2003 May;41(5):1008-15

Nephrology Associates, Santa Rosa, CA, USA.

Background: Dialysis adequacy targets frequently are difficult to achieve in large hemodialysis patients. Dual dialyzers can be used to improve clearance. It is unknown whether series or parallel configurations are superior.

Methods: Eighteen large hemodialysis patients (mean weight, 92.4 kg) were enrolled in a randomized, crossover trial to directly compare dual dialyzers in parallel and series configurations. Treatment times, blood flow rates, and dialysate flow rates were kept constant.

Results: Compared with a single dialyzer, parallel dual dialyzers increased the single-pool Kt/V (spKt/V) from 1.25 +/- 0.22 to 1.43 +/- 0.29 (P < 0.003). Series dual dialyzers improved urea clearance measured by spKt/V (spKt/V(urea)) to 1.46 +/- 0.26 (P < 0.0003 compared with a single dialyzer). Kt/V and urea reduction ratio of dual dialyzers in parallel were not significantly different from those of dual dialyzers in series. Half the subjects failed to meet the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative recommended adequacy target for spKt/V(urea) of 1.2 or less using a single dialyzer. With the use of dual dialyzers, 83% of subjects achieved this adequacy target. Serum levels of a middle molecule, beta2-microglobulin, were reduced 34% after 2 months of dual-dialyzer therapy. Cost analysis estimates annual net savings of 1,260 dollars with dual-dialyzer therapy, primarily from projected savings in inpatient expenses.

Conclusion: In large hemodialysis patients, our study shows that dual dialyzers in parallel and series are equally effective at improving urea clearance without prolonging dialysis treatment times.
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http://dx.doi.org/10.1016/s0272-6386(03)00198-7DOI Listing
May 2003
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