Epidemiological and virological findings during an outbreak of equine influenza in Uruguay in 2018

Equine influenza is one of the major respiratory infectious diseases in horses. In 2018, equine influenza virus (EIV) was confirmed as the cause of outbreaks of respiratory disease in horses in Chile and Argentina. In the same year, for the first time in Uruguay, EIV infection was confirmed by isolation and molecular analysis to be the cause of respiratory disease among hundreds of clinically affected thoroughbred horses in training and racing facilities. The virus was detected in nasopharyngeal swabs by a pan-reactive influenza type A realtime reverse transcription polymerase chain reaction (rRT-PCR). The partial nucleotide sequence of the haemagglutinin 1 (HA1 ) gene (994 base pairs) was determined and analysed phylogenetically using MEGA X software. Amino acid sequence alignments were constructed, and serum samples were tested by haemagglutination inhibition and single radial haemolysis. The diagnosis of EIV was confirmed by rRT-PCR, virus isolation and serological testing. The phylogenetic analysis of the partial HA1 gene sequence of the isolated virus indicated that it belongs to clade 1 of the Florida sub-lineage of the American lineage and is closely related to viruses isolated in the recent past. Study of the HA1 region (331 amino acids) of the virus identified in horses in racing facilities in Uruguay displayed the highest amino acid sequence identity with viruses detected in Argentina, Chile and the United Kingdom in 2018. The surveillance data reported illustrate the international spread of EIVs and support the recommendation of the World Organisation for Animal Health (OIE) Expert Surveillance Panel to include viruses of the Florida sub-lineage in vaccines.

RID: Evaluation of the Possible Inhibiting Effect of the Proinflammatory Signaling Induced by TNF-α through NF-κβ and AP-1 in Two Cell Lines of Breast Cancer

Receptor internalization and degradation (RID), is a transmembrane protein coded within the E3 region expression cassette of adenoviruses. RID downregulates the cell surface expression of epidermal growth factor receptor (EGFR), tumor necrosis factor receptor (TNFR), and apoptosis antigen 1 (FAS), causing a reduction of the effects of their respective ligands. In addition, RID inhibits apoptosis by decreasing the secretion of TNF-related apoptosis-inducing ligand (TRAIL) by normal tissue cells. In this article, we report that RID inhibited chemokine expression in human breast cancer cell line MDA-MB-231 but showed no effect in cell line MCF7. These dissimilar results may be due to the different molecular and functional properties of both cell lines. Therefore, it is necessary to replicate this study in other breast cancer cell models.

A multimodal intervention program to control a long-term Acinetobacter baumannii endemic in a tertiary care hospital

Background

Acinetobacter baumannii causes frequently nosocomial infections worldwide. Its ability to survive on dry surfaces facilitates its spread and the persistence of endemic situations, especially in the intensive care units (ICUs).

The objective of this paper is to describe a multicomponent intervention program designed to control a hyperendemic persistence of multidrug-resistant A. baumannii (MDR-Ab) and to characterize its impact.

Methods

Design: Quasi-experimental intervention study based on open cohorts.

Setting: Public tertiary referral centre. Period: January 2009–August 2017.

Intervention: multifaceted program based on environmental decontamination, hand hygiene, antimicrobial stewardship, contact precautions, active surveillance, weekly reports and regular meetings.

Analysis: joinpoint regression and interrupted time-series analysis.

Results

The intervention was successfully implemented. Through the study period, the compliance with contact precautions changed from 0 to 100% and with hand hygiene, from 41.8 to 82.3%. Between 2012 and 2016, the antibiotic consumption decreased from 165.35 in to 150.44 daily-defined doses/1000 patients-days in the ICU. The incidence density of MDR-Ab in the ICU was 10.9 cases/1000 patients-days at the beginning of the intervention. After this moment, the evolution of the incidence density of MDR-Ab was: between months 0 and 6°, it remained stable; between months 7° and 10°: there was an intense decrease, with an average monthly percentage change (AMPC) = − 30.05%; from 11° month until the end, the decrease was lighter but continuous (AMPC:-2.77%), achieving an incidence density of 0 cases/1000 patients-days on the 18° month, without any new case for 12 months. From the 30° month until the end of the study period, several little outbreaks of MDR-Ab were detected, all of them rapidly controlled. The strains of MDR-Ab isolated during these outbreaks were not clonally related with the previously endemic one, which supports its eradication from the environmental reservoirs.

Conclusion

The multicomponent intervention performed by a multidisciplinary team was effective to eradicate the endemic MDR-Ab.

Determination of Low-Level Pesticide Residues in Soft Drinks and Sports Drinks by Liquid Chromatography with Tandem Mass Spectrometry: Collaborative Study

A collaborative study was conducted on a method for the measurement of 11 low-level pesticide residues in soft drinks and sports drinks by liquid chromatography with tandem mass spectrometry. The pesticide residues determined in this study were alachlor, atrazine, butachlor, isoproturon, malaoxon, monocrotophos, methyl paraoxon, phorate, phorate sulfone, phorate sulfoxide, and 2,4-dichlorophenoxyacetic acid (2,4-D). Blind fortification solutions containing 3 different levels of pesticide residues were provided to 9 collaborating laboratories to create test samples at concentrations of 0, 0.1, and 0.5 g/L with a 10-fold concentration for phorate in a total of 6 matrixes (2 colas, 1 diet cola, 1 clear lemon-lime soft drink, 1 orange soft drink, and 1 sports drink). Good qualitative performance of the method was demonstrated for all pesticide residues. Reproducibility relative standard deviation (RSDR) ranged from 7 to 151 for alachlor, atrazine, butachlor, isoproturon, malaoxon, monocrotophos, methyl paraoxon, phorate, phorate sulfone, phorate sulfoxide, and 2,4-D at the 0.1 g/L level (1.0 g/L for phorate). At 0.5 g/L (5.0 g/L for phorate), RSDR ranged from 9 to 57 for alachlor, atrazine, butachlor isoproturon, malaoxon, monocrotophos, methyl paraoxon, phorate, phorate sulfone, phorate sulfoxide, and 2,4-D in all matrixes. Repeatability relative standard deviation (RSDr), applicable to the diet cola and sports drink, ranged from 0 to 124 for the 11 pesticide residues at the 0.1 g/L level (1.0 g/L for phorate). At 0.5 g/L (5.0 g/L for phorate), RSDr ranged from 4 to 26. Recoveries for the 11 pesticide residues in all matrixes ranged from 84 to 300 at the 0.1 g/L level (1.0 g/L for phorate) and from 66 to 127 at the 0.5 g/L (5.0 g/L for phorate) level. Coefficients of determination (r2) of the matrix-matched calibration curves were 0.95. It is recommended that the method be accepted by AOAC as Official First Action with a limit of quantification of 0.5 g/L for alachlor, atrazine, butachlor, isoproturon, malaoxon, methyl paraoxon, monocrotophos, phorate sulfone, phorate sulfoxide, and 2,4-D and 5.0 g/L for phorate.

Determination of Pesticide Residues (>0.5 g/L) in Soft Drinks and Sports Drinks by Gas Chromatography with Mass Spectrometry: Collaborative Study

A collaborative study was conducted on a method for the measurement of 19 low-level pesticide residues in soft drinks and sports drinks by gas chromatography with mass spectrometry (GC/MS). The pesticide residues determined were 2,4-dichlorodiphenyldichloroethylene (2,4-DDE); 2,4-dichlorodiphenyldichloroethane (2,4-DDD); 4,4-dichlorodiphenyldichloroethylene (4,4-DDE); 2,4-dichlorodiphenyltrichloroethane (2,4-DDT); 4,4-dichlorodiphenyltrichloroethane (4,4-DDT); 4,4-dichlorodiphenyldichloroethane (4,4-DDD); -endosulfan; endosulfan-sulfate; dieldrin; aldrin; ethion; chlorpyrifos; -endosulfan; malathion; methyl-parathion; -hexachlorocyclohexane (-HCH); -HCH; -HCH; and -HCH. Blind fortification solutions containing 4 different levels of pesticide residues (0, 0.1, 0.5, and 1.0 g/L) were provided to 8 collaborating laboratories who used them to create test samples in 6 matrixes (also provided): 2 colas, a diet cola, a clear lemon-lime soft drink, an orange soft drink, and a sports drink. Reproducibility (RSDR) for all 19 pesticide residues in all matrixes ranged from 7 to 151 at the 0.1 g/L level, 11 to 121 at 0.5 g/L, and 14 to 67 at 1.0 g/L. Repeatability (RSDr), applicable to the diet cola and the sports drink, ranged from 1 to 76 for the 19 pesticide residues at the 0.1 g/L level, 9 to 38 at 0.5 g/L, and 9 to 38 at 1.0 g/L. Recoveries for the 19 pesticide residues in allmatrixes ranged from 77 to 645 at the 0.1 g/L level, 60 to 231 at 0.5 g/L, and 61 to 146 at 1.0 g/L. It is recommended that the method be accepted by AOAC as Official First Action with a limit of quantification (LOQ) equal to 0.5 g/L for 4,4-DDT; 2,4-DDT; 2,4-DDD; 4,4-DDE; 4,4-DDD; 2,4-DDE; aldrin; dieldrin; -endosulfan; endosulfan-sulfate; chlorpyrifos; and ethion, and an LOQ equal to 1.0 g/L for -endosulfan; -HCH; -HCH; -HCH; -HCH; methyl-parathion; and malathion.

Determination of Ephedrine Alkaloids in Botanicals and Dietary Supplements by HPLC-UV: Collaborative Study

An international collaborative study was conducted of a high-performance liquid chromatography (HPLC)-UV method for the determination of the major (ephedrine [EP] and pseudoephedrine [PS]) and minor (norephedrine [NE], norpseudoephedrine [NP], methylephedrine [ME], and methylpseudoephedrine [MP]) alkaloids in selected dietary supplements representative of the commercially available products. Ten collaborating laboratories determined the ephedrine-type alkaloid content in 8 blind replicate samples. Five products contained ephedra ground herb or ephedra extract. These 5 products included ground botanical raw material of Ephedra sinica, a common powdered extract of Ephedra sinica, a finished product containing only Ephedra sinica ground botanical raw material, a complex multicomponent dietary supplement containing Ma Huang, and a high-protein chocolate flavored drink mix containing Ma Huang extract. In addition, collaborating laboratories received a negative control and negative control spiked with ephedrine alkaloids at high and low levels for recovery studies. Test extracts were treated to solid-phase extraction using a strong-cation exchange column to help remove interferences. The HPLC analyses were performed on a polar-embedded phenyl column using UV detection at 210 nm. Repeatability relative standard deviations (RSD r) ranged from 0.64–3.0% for EP and 2.0–6.6% for PS, excluding the high protein drink mix. Reproducibility relative standard deviations (RSD R) ranged from 2.1–6.6% for EP and 9.0–11.4% for PS, excluding the high protein drink mix. Recoveries ranged from 84.7–87.2% for EP and 84.6–98.2% for PS. The data developed for the minor alkaloids are more variable with generally unsatisfactory HORRATS (i.e., >2). However, since these alkaloids generally add little to the total alkaloid content of the products, the method gives satisfactory results in measuring total alkaloid content (RSD r 0.85–3.13%; RSDR 2.03–10.97%, HORRAT 0.69–3.23, exclusive of the results from the high protein drink). On the basis of these results, the method is recommended for Official First Action for determination of EP and PS in dietary supplements exclusive of the high protein drinks.

Determination of Ephedrine Alkaloids in Human Urine and Plasma by Liquid Chromatography/Tandem Mass Spectrometry: Collaborative Study

A collaborative study was conducted to evaluate the accuracy and precision of a method for ephedrine-type alkaloids (i.e., norephedrine, norpseudoephedrine, ephedrine, pseudoephedrine, methylephedrine, and methylpseudoephedrine) in human urine and plasma. The amount of ephedrine-type alkaloids present was determined using liquid chromatography (LC) with tandem mass selective detection. The test samples were diluted to reflect a concentration of 5.00–100 ng/mL for each alkaloid. An internal standard was added and the alkaloids were separated using a 5 μm phenyl LC column with an ammonium acetate, glacial acetic acid, acetonitrile, and water mobile phase. Eight blind duplicates of human urine and eight blind duplicates of human plasma were analyzed by 10 collaborators. In addition to negative controls, test portions of urine and plasma were fortified at 3 different levels with each of the 6 ephedrine-type alkaloids at approximately 1, 2, and 5 μg/mL for urine and 100, 200, and 500 ng/mL for plasma. On the basis of the accuracy and precision results for this collaborative study, it is recommended that this method be adopted Official First Action for the determination of 6 different ephedrine-type alkaloids in human urine and plasma.

Determination of Ephedrine Alkaloids in Dietary Supplements and Botanicals by Liquid Chromatography/Tandem Mass Spectrometry: Collaborative Study

An interlaboratory study was conducted to evaluate the accuracy and precision of a method for ephedrine-type alkaloids [i.e., norephedrine (NE), norpseudoephedrine (NPE), ephedrine (E), pseudoephedrine (PE), methylephedrine (ME), and methylpseudoephedrine (MPE)] in dietary supplements and botanicals. The amount of ephedrine-type alkaloids present was determined using liquid chromatography with tandem mass selective detection. The samples were diluted to reflect a concentration of 0.0200 to 1.00 μg/mL for each alkaloid. An internal standard was added and the alkaloids were separated using a 5 μm phenyl LC column with an ammonium acetate, glacial acetic acid, acetonitrile, and water mobile phase. Eight blind duplicates of dietary supplements or botanicals were analyzed by 10 collaborators. Included was a negative control, ephedra nevadensis, and negative controls fortified at 2 different levels with each of the 6 ephedrine-type alkaloids. The spike levels were approximately 100 and 1000 μg/g for NE, 100 and 600 μg/g for NPE, 6500 and 65 000 μg/g for E, 1000 and 10 000 μg/g for PE, 300 and 3000 μg/g for ME, and 100 and 1000 μg/g for MPE. On the basis of the accuracy and precision results for this interlaboratory study, it is recommended that this method be adopted Official First Action for the determination of 6 different individual ephedrine-type alkaloids in dietary supplements and botanicals.

P6351A point-of-care risk score predicts 30-day readmission in patients hospitalized with heart failure (HF): derivation and validation of the LENT index

Background

Risk prediction models in heart failure (HF) are typically complex, derived retrospectively from administrative databases, and modest in their ability to discriminate between high, medium, and low risk categories. The complexity of these models makes them difficult to use at the point of care.

Purpose

To determine if a simple risk index using Length of hospital stay (L), number of Emergency department visits in the preceding 6 months (E), and either admission or discharge N-Terminal (NT) prohormone of Brain Natriuretic Peptide (pro-BNP) at the point of care can predict 30-day readmissions in patients hospitalized for HF.

Methods

This is a sub-study of the Patient-Centered Care Transitions in HF (PACT-HF) stepped-wedge cluster randomized trial. We included 772 patients hospitalized for HF at 10 Canadian hospitals. We used log-binomial regression models with Length of stay, Emergency department visits in the preceding 6 months, and either admission or discharge N-Terminal prohormone of Brain Natriuretic Peptide (NT-pro-BNP) as the predictor variables and 30-day all-cause readmission as the outcome. We derived the LENT risk score from the β-coefficients of the regression model (Fig. 1). All the models were adjusted for post-discharge services. We assessed model discrimination with C-statistics and model calibration with the net reclassification index (NRI). We used the bootstrapping approach with 100 runs for internal validation.

Results

The LENT index had a possible score ranging from 1 to 13 (Fig 1). Increments in the LENT risk score were associated with an increased risk of 30-day readmission; a 1-point increase in the LENT index using the admission and discharge NT-pro-BNP predicted a 23% and 19% increase in 30-day readmission risk, respectively. The internal validation produced similar results. Compared to a null model, the LE index had an NRI of 0.35 [95% CI 0.18, 0.53], and admission and discharge NT-pro-BNP further improved calibration of the LE index (NRI 0.15 [95% CI 0, 0.32] and 0.20 [95% CI 0.03, 0.37], respectively). The LENT index offered modest discrimination for 30-day readmission (C-statistic 0.64 [95% CI 0.59, 0.69]), similar to more complex risk models.

Figure 1. The LENT index scoring system

Conclusion

A simple risk index based on Length of stay, Emergent visits, and NT-pro-BNP at the point of care can reliably predict 30-day readmissions. The LENT index offers ease of use over traditional risk prediction models.

Acknowledgement/Funding

Canadian Institutes of Health Research, Ontario MOHLTC, Roche Diagnostics

Standards for the diagnosis and management of complex regional pain syndrome: Results of a European Pain Federation task force

Background

Complex regional pain syndrome is a painful and disabling post‐traumatic primary pain disorder. Acute and chronic complex regional pain syndrome (CRPS) are major clinical challenges. In Europe, progress is hampered by significant heterogeneity in clinical practice. We sought to establish standards for the diagnosis and management of CRPS.

Methods

The European Pain Federation established a pan‐European task force of experts in CRPS who followed a four‐stage consensus challenge process to produce mandatory quality standards worded as grammatically imperative (must‐do) statements.

Results

We developed 17 standards in 8 areas of care. There are 2 standards in diagnosis, 1 in multidisciplinary care, 1 in assessment, 3 for care pathways, 1 in information and education, 4 in pain management, 3 in physical rehabilitation and 2 on distress management. The standards are presented and summarized, and their generation and consequences were discussed. Also presented are domains of practice for which no agreement on a standard could be reached. Areas of research needed to improve the validity and uptake of these standards are discussed.

Conclusion

The European Pain Federation task force present 17 standards of the diagnosis and management of CRPS for use in Europe. These are considered achievable for most countries and aspirational for a minority of countries depending on their healthcare resource and structures.

Significance

This position statement summarizes expert opinion on acceptable standards for CRPS care in Europe.

SEIS: Insight's Seismic Experiment for Internal Structure of Mars

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars' surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking's Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars' surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of M w ∼ 3 at 40 ∘ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (10.1007/s11214-018-0574-6) contains supplementary material, which is available to authorized users.

Preoperative oral antibiotic prophylaxis reduces Pseudomonas aeruginosa surgical site infections after elective colorectal surgery: a multicenter prospective cohort study

Background

Healthcare-associated infections caused by Pseudomonas aeruginosa are associated with poor outcomes. However, the role of P. aeruginosa in surgical site infections after colorectal surgery has not been evaluated. The aim of this study was to determine the predictive factors and outcomes of surgical site infections caused by P. aeruginosa after colorectal surgery, with special emphasis on the role of preoperative oral antibiotic prophylaxis.

Methods

We conducted an observational, multicenter, prospective cohort study of all patients undergoing elective colorectal surgery at 10 Spanish hospitals (2011–2014). A logistic regression model was used to identify predictive factors for P. aeruginosa surgical site infections.

Results

Out of 3701 patients, 669 (18.1%) developed surgical site infections, and 62 (9.3%) of these were due to P. aeruginosa. The following factors were found to differentiate between P. aeruginosa surgical site infections and those caused by other microorganisms: American Society of Anesthesiologists’ score III–IV (67.7% vs 45.5%, p = 0.001, odds ratio (OR) 2.5, 95% confidence interval (95% CI) 1.44–4.39), National Nosocomial Infections Surveillance risk index 1–2 (74.2% vs 44.2%, p < 0.001, OR 3.6, 95% CI 2.01–6.56), duration of surgery ≥75thpercentile (61.3% vs 41.4%, p = 0.003, OR 2.2, 95% CI 1.31–3.83) and oral antibiotic prophylaxis (17.7% vs 33.6%, p = 0.01, OR 0.4, 95% CI 0.21–0.83). Patients with P. aeruginosa surgical site infections were administered antibiotic treatment for a longer duration (median 17 days [interquartile range (IQR) 10–24] vs 13d [IQR 8–20], p = 0.015, OR 1.1, 95% CI 1.00–1.12), had a higher treatment failure rate (30.6% vs 20.8%, p = 0.07, OR 1.7, 95% CI 0.96–2.99), and longer hospitalization (median 22 days [IQR 15–42] vs 19d [IQR 12–28], p = 0.02, OR 1.1, 95% CI 1.00–1.17) than those with surgical site infections due to other microorganisms. Independent predictive factors associated with P. aeruginosa surgical site infections were the National Nosocomial Infections Surveillance risk index 1–2 (OR 2.3, 95% CI 1.03–5.40) and the use of oral antibiotic prophylaxis (OR 0.4, 95% CI 0.23–0.90).

Conclusions

We observed that surgical site infections due to P. aeruginosa are associated with a higher National Nosocomial Infections Surveillance risk index, poor outcomes, and lack of preoperative oral antibiotic prophylaxis. These findings can aid in establishing specific preventive measures and appropriate empirical antibiotic treatment.

Multistate modelling to estimate excess length of stay and risk of death associated with organ/space infection after elective colorectal surgery

BACKGROUND

Accounting for time-dependency and competing events are strongly recommended to estimate excess length of stay (LOS) and risk of death associated with healthcare-associated infections.

AIM

To assess the effect of organ/space (OS) surgical site infection (SSI) on excess LOS and in-hospital mortality in patients undergoing elective colorectal surgery (ECS).

METHODS

A multicentre prospective adult cohort undergoing ECS, January 2012 to December 2014, at 10 Spanish hospitals was used. SSI was considered the time-varying exposure and defined as incisional (superficial and deep) or OS. Discharge alive and death were the study endpoints. The mean excess LOS was estimated using a multistate model which provided a weighted average based on the states patients passed through. Multivariate Cox regression models were used to assess the effect of OS-SSI on risk of discharge alive or in-hospital mortality.

FINDINGS

Of 2778 patients, 343 (12.3%) developed SSI: 194 (7%) OS-SSI and 149 (5.3%) incisional SSI. Compared to incisional SSI or no infection, OS-SSI prolonged LOS by 4.2 days (95% confidence interval (CI): 4.1-4.3) and 9 days (8.9-9.1), respectively, reduced the risk of discharge alive (adjusted hazard ratio (aHR): 0.36 (95% CI: 0.28-0.47) and aHR: 0.17 (0.14-0.21), respectively), and increased the risk of in-hospital mortality (aHR: 8.02 (1.03-62.9) and aHR: 10.7 (3.7-30.9), respectively).

CONCLUSION

OS-SSI substantially extended LOS and increased risk of death in patients undergoing ECS. These results reinforce OS-SSI as the SSI with the highest health burden in ECS.

Factors Affecting β2-Microglobulin Plasma Concentration during Hemodialysis

We studied ten patients on hemodialysis (HD) treated in sequence with cuprophan (CU), ethylenevinylalcohol (EVAL), polyacrylonitrile (A-69) and polysulphone (PSP) membrane dialyzers. ß2-microglobulin (ß2m) was measured by radioimmunoassay in plasma and dialysate samples. Plasma concentrations were corrected for changes in extracellular volume (ECV). We also studied adsorption in vitro by incubating the above membranes with I-125-labelled ß2m. There were no changes in ß2m plasma concentration after HD with CU dialyzers, but a significant decrease was observed with the other membranes tested. Filtration of ß2m across the dialyzer was absent with CU and minimal with EVAL. However, large amounts were recovered from dialysate with the high-permeability dialyzers, AN-69 and PSP. In vitro studies showed that maximal adsorption capacity was obtained with AN-69 (73%) compared to 9% with CU, 4% with EVAL and 7% with PSP. In summary, ß2m clearance with PSP is achieved through greater removal of this protein by mass transport across the membrane. The mechanism by which ß2m is removed from blood during AN-69 dialysis seems to include both adsorption to and filtration by the membrane itself.