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Background: Frailty is associated with adverse outcomes in advanced heart failure. We studied the impact of frailty on postoperative outcomes in bridge to transplant (BTT) durable mechanical circulatory support (MCS) recipients., Methods: Patients undergoing left ventricular assist device (LVAD, n = 96) or biventricular support (BiV, n = 11) as BTT underwent frailty assessment. Frailty was defined as ≥ 3 physical domains of the Fried's Frailty Phenotype (FFP) or ≥ 2 physical domains of the FFP plus cognitive impairment on the Montreal Cognitive Assessment (MoCA)., Results: No difference in mortality at 360 days was observed in frail (n = 6/38, 15.8%) vs non-frail (n = 4/58, 6.9%) LVAD supported patients, p = 0.19. However, there was a significant excess mortality in frail BiV (n = 4/5) vs non-frail BiV (n = 0/6) supported patients, p = 0.013. In all patients, frail patients compared to non-frail patients experienced longer intensive care unit stay, 12 vs 6 days (p < 0.0001) and hospital length of stay, 48 vs 27 days (p < 0.0001). There was no difference in hemocompatibility and infection related adverse events. The majority (n = 22/29, 75.9%) of frail patients became non-frail following MCS; contrastingly, a minority (n = 3/42, 7.1%) became frail from being non-frail (p = 0.0003)., Conclusions: Abnormal markers of frailty are common in patients undergoing BTT-MCS support and those used herein predict mortality in BiV-supported patients, but not in LVAD patients. These findings may help us better identify patients who will benefit most from BiV-BTT therapy., (Copyright © 2022 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Background: In late 2012, ivacaftor became available in the UK for people with cystic fibrosis (CF) aged 6 years and over with a G551D mutation. Long-term changes in treatment patterns have not previously been reported. We investigated long-term treatment patterns in people with CF with a G551D mutation who took ivacaftor and compared these with non-ivacaftor-treated cohorts using the UK Cystic Fibrosis Registry., Methods: Using 2007-2018 data we compared treatment patterns between four cohorts: 1: ivacaftor-treated; 2: ivacaftor era (2013-2018), ineligible genotype (no G551D mutation); 3: pre-ivacaftor era (2007-2012), eligible genotype (G551D mutation); 4: pre-ivacaftor era, ineligible genotype. Treatments included: inhaled antibiotics, dornase alfa, hypertonic saline, chronic oral antibiotics and supplementary feeding., Results: Up to 2012 the percentages of people taking each treatment were similar between the two cohorts defined by genotype and tended to increase by year with a similar slope. Once ivacaftor was introduced, the use of other treatments tended to decrease or remain stable by year for the ivacaftor-treated cohort, whereas it remained stable or increased in the non-ivacaftor-treated cohort. This led to differences in treatment use between the two cohorts in the ivacaftor-era, which became more marked over time., Conclusions: We have shown a clear divergence in treatment patterns since the introduction of ivacaftor in a number of key treatments widely used in CF. Further research is needed to investigate whether the differences in treatment patterns are associated with changes in health outcomes., Competing Interests: Conflict of interest statement GD has received personal fees from Chiesi Limited for lectures, unrelated to the current work. She is co-Chief Investigator for the CF STORM clinical trial. EG has no conflicts of interest to declare. RHK received funding from a Circle of Care Award from Vertex., (Copyright © 2021. Published by Elsevier B.V.)

Background: Frailty is prevalent in the patients with advanced heart failure; however, its impact on clinical outcomes after heart transplantation (HTx) is unclear. The aim of this study was to assess the impact of pre-transplant frailty on mortality and the duration of hospitalization after HTx., Methods: We retrospectively reviewed the post-transplant outcomes of 140 patients with advanced heart failure who had undergone frailty assessment within the 6-month interval before HTx: 43 of them were frail (F) and 97 were non-frail (NF)., Results: Post-transplant survival rates for the NF cohort at 1 and 12 months were 97% (93-100) and 95% (91-99) (95% CI), respectively. In contrast, post-transplant survival rates for the F cohort at the same time points were 86% (76-96) and 74% (60-84) (p < 0.0008 vs NF cohort), respectively. The Cox proportional hazards regression analysis demonstrated that pre-transplant frailty was an independent predictor of post-transplant mortality with a hazard ratio of 3.8 (95% CI: 1.4-10.5). Intensive care unit and hospital length of stay were 2 and 7 days longer in the F cohort (both p < 0.05), respectively, than in the NF cohort., Conclusions: Frailty within 6 months before HTx is independently associated with increased mortality and prolonged hospitalization after transplantation. Future research should focus on the development of strategies to mitigate the adverse effects of pre-transplant frailty., (Copyright © 2020 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Widely used loss functions for CNN segmentation, e.g., Dice or cross-entropy, are based on integrals over the segmentation regions. Unfortunately, for highly unbalanced segmentations, such regional summations have values that differ by several orders of magnitude across classes, which affects training performance and stability. We propose a boundary loss, which takes the form of a distance metric on the space of contours, not regions. This can mitigate the difficulties of highly unbalanced problems because it uses integrals over the interface between regions instead of unbalanced integrals over the regions. Furthermore, a boundary loss complements regional information. Inspired by graph-based optimization techniques for computing active-contour flows, we express a non-symmetric L 2 distance on the space of contours as a regional integral, which avoids completely local differential computations involving contour points. This yields a boundary loss expressed with the regional softmax probability outputs of the network, which can be easily combined with standard regional losses and implemented with any existing deep network architecture for N-D segmentation. We report comprehensive evaluations and comparisons on different unbalanced problems, showing that our boundary loss can yield significant increases in performances while improving training stability. Our code is publicly available 1 ., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Background: Infertility is a common presentation of female genital tuberculosis in endemic areas. Female genital tuberculosis-related maternal and neonatal complications have increased in recent years after assisted reproductive technology treatments. Despite rising emigration rates to the United States, guidelines to identify those with latent tuberculosis or female genital tuberculosis in fertility centers do not exist., Objective: This study aimed to characterize the prevalence of female genital tuberculosis in infertile patients at our academic fertility center., Study Design: This is a prospective cohort study. All patients presenting for infertility evaluation between January 2014 and January 2017 were assessed for risk factors for latent tuberculosis. Patients at risk for latent tuberculosis underwent screening using QuantiFERON-TB Gold serum assay. QuantiFERON-TB Gold-positive patients underwent further testing for female genital tuberculosis consisting of endometrial biopsy with histopathologic examination by a clinical pathologist, polymerase chain reaction for tuberculosis, and culture for acid-fast Mycobacterium tuberculosis., Results: Twenty-five of 323 infertility patients (7.7%) screened for latent tuberculosis had positive QuantiFERON-TB Gold results. A greater number of patients with a positive test result for QuantiFERON-TB Gold were foreign born than those with a negative test result for QuantiFERON-TB Gold (92% vs 29%; P<.001). Of note, the QuantiFERON-TB Gold-positive population had a higher incidence of both recurrent pregnancy loss (28% vs 7%; P=.003) and Asherman syndrome (8% vs 0.3%; P<.001). Among those with a positive test result for QuantiFERON-TB Gold, chest x-ray was abnormal in only 2 patients (8.0%). Endometrium evaluation revealed abnormalities in 2 patients (8.0%), in whom chest x-ray was normal, with 1 showing evidence of female genital tuberculosis. This was indicated by histology consistent with chronic granulomatous endometritis and positive endometrial testing for tuberculosis by polymerase chain reaction, acid-fast bacilli smear, and culture for Mycobacterium tuberculosis., Conclusion: Although the prevalence of female genital tuberculosis in infertile women in the United States seems to be low, this study indicates that it can be underdiagnosed without utilization of multiple diagnostic modalities including endometrial sampling. Given the potential for serious maternal and neonatal morbidity in affected patients utilizing assisted reproductive technology, we propose that all at-risk women seeking infertility care in the United States be screened for latent tuberculosis. In patients who screen positive, endometrial biopsy should be obtained for evaluation by histology, polymerase chain reaction, and culture for Mycobacterium tuberculosis to rule out female genital tuberculosis before infertility treatments are initiated., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Weakly-supervised learning based on, e.g., partially labelled images or image-tags, is currently attracting significant attention in CNN segmentation as it can mitigate the need for full and laborious pixel/voxel annotations. Enforcing high-order (global) inequality constraints on the network output (for instance, to constrain the size of the target region) can leverage unlabeled data, guiding the training process with domain-specific knowledge. Inequality constraints are very flexible because they do not assume exact prior knowledge. However, constrained Lagrangian dual optimization has been largely avoided in deep networks, mainly for computational tractability reasons. To the best of our knowledge, the method of Pathak et al. (2015a) is the only prior work that addresses deep CNNs with linear constraints in weakly supervised segmentation. It uses the constraints to synthesize fully-labeled training masks (proposals) from weak labels, mimicking full supervision and facilitating dual optimization. We propose to introduce a differentiable penalty, which enforces inequality constraints directly in the loss function, avoiding expensive Lagrangian dual iterates and proposal generation. From constrained-optimization perspective, our simple penalty-based approach is not optimal as there is no guarantee that the constraints are satisfied. However, surprisingly, it yields substantially better results than the Lagrangian-based constrained CNNs in Pathak et al. (2015a), while reducing the computational demand for training. By annotating only a small fraction of the pixels, the proposed approach can reach a level of segmentation performance that is comparable to full supervision on three separate tasks. While our experiments focused on basic linear constraints such as the target-region size and image tags, our framework can be easily extended to other non-linear constraints, e.g., invariant shape moments (Klodt and Cremers, 2011) and other region statistics (Lim et al., 2014). Therefore, it has the potential to close the gap between weakly and fully supervised learning in semantic medical image segmentation. Our code is publicly available., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Aim: To describe the ECPR experience of two Australian ECMO centres, with regards to survival and neurological outcome, their predictors and complications., Methods: Retrospective observational study of prospectively collected data on all patients who underwent extracorporeal cardiopulmonary resuscitation (ECPR) at two academic ECMO referral centres in Sydney, Australia., Measurements and Main Results: Thirty-seven patients underwent ECPR, 25 (68%) were for in-hospital cardiac arrests. Median age was 54 (IQR 47-58), 27 (73%) were male. Initial rhythm was ventricular fibrillation or pulseless ventricular tachycardia in 20 patients (54%), pulseless electrical activity (n=14, 38%), and asystole (n=3, 8%). 27 (73%) arrests were witnessed and 30 (81%) patients received bystander CPR. Median time from arrest to initiation of ECMO flow was 45min (IQR 30-70), and the median time on ECMO was 3days (IQR 1-6). Angiography was performed in 54% of patients, and 27% required subsequent coronary intervention (stenting or balloon angioplasty 24%). A total of 13 patients (35%) survived to hospital discharge (IHCA 33% vs. OHCA 37%). All survivors were discharged with favourable neurological outcome (Cerebral Performance Category 1 or 2). Pre-ECMO lactate level was predictive of mortality OR 1.35 (1.06-1.73, p=0.016)., Conclusions: In selected patients with refractory cardiac arrest, ECPR may provide temporary support as a bridge to intervention or recovery. We report favourable survival and neurological outcomes in one third of patients and pre-ECMO lactate levels predictive of mortality. Further studies are required to determine optimum selection criteria for ECPR., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: The aim of this study was to identify whether the addition of cognitive impairment, depression, or both, to the assessment of physical frailty provides better outcome prediction in patients with advanced heart failure referred for heart transplantation (HT)., Methods: Beginning in March 2013, all patients with advanced heart failure referred to our Transplant Unit have undergone a physical frailty assessment using the Fried frailty phenotype. Cognition was assessed with the Montreal Cognitive Assessment and depression with the Depression in Medical Illness questionnaire. We assessed the value of 4 composite frailty measures: physical frailty (PF ≥ 3 of 5 = frailty), "cognitive frailty" (CogF ≥ 3 of 6 = frail), "depressive frailty" (DepF ≥ 3 of 6 = frail), and "cognitive-depressive frailty" (ComF ≥ 3 of 7 = frail) in predicting outcomes., Results: Frailty was assessed in 156 patients (109 men, 47 women), aged 53 ± 13 years, and with a left ventricular ejection fraction of 27% ± 14%. Inclusion of cognitive impairment or depression in the definition of frailty increased the proportion classified as frail from 33% using PF to 42% using ComF. During follow-up, 28 patients died before ventricular assist device implantation or HT. Frailty was associated with significantly lower ventricular assist device- and HT-free survival, with CogF best capturing early mortality: 12-month survival for non-frail and frail cohorts was 81% ± 5% vs 58% ± 10% (p < 0.02) using PF and 85% ± 5% vs 56% ± 9% (p < 0.002) using CogF. Combining the Depression in Medical Illness score with PF or CogF did not strengthen the relationship between frailty and mortality., Conclusions: The addition of cognitive impairment to the assessment of PF strengthened its capacity to identify advanced heart failure patients referred for HT who are at high risk of early death., (Copyright © 2016 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)

Background: There is limited information on outcomes using the HeartWare ventricular assist device (HVAD; HeartWare, Framington, MA) as a biventricular assist device, especially with respect to site of right ventricular assist device (RVAD) implantation., Methods: Outcomes in 13 patients with dilated cardiomyopathy and severe biventricular failure who underwent dual HVAD implantation as bridge to transplantation between August 2011 and October 2014 were reviewed., Results: Of 13 patients, 10 were Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) Level 1, and 3 were INTERMACS Level 2. Mean age was 45 ± 11 years, and mean body mass index was 26 ± 4 kg/m(2). There were 7 patients on temporary mechanical support pre-operatively (extracorporeal life support, n = 5; intra-aortic balloon pump, n = 2). The median hospital length of stay was 53 days (interquartile range [IQR] 33-70 days) with a median intensive care unit length of stay of 14 days (IQR 8-36 days). The median length of support on device was 269 days (IQR 93-426 days). The right HVAD was implanted in the right ventricular (RV) free wall in 6 patients and in the right atrial (RA) free wall in 7 patients. Transplantation was successfully performed in 5 patients, and overall survival for the entire cohort was 54%. RVAD pump thrombosis occurred in 3 of 6 RV pumps and 1 of 7 RA pumps. No left ventricular assist device pump thrombosis was observed. Bleeding tended to be higher in the RV implantation group (3 of 6 vs 0 of 7). During follow up, 6 patients died (4 of 7 in the RA group vs 2 of 6 in the RV group). Cause of death was multiple-organ failure in 3 patients, sepsis in 2 patients, and intracerebral hemorrhage in 1 patient., Conclusions: Critically ill patients who require biventricular support can be successfully bridged to transplant using 2 HVADs. RA implantation may allow right heart support with lower pump thrombosis and bleeding complications, although this was at the expense of a higher mortality in this cohort., (Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.)

Background: Orthotopic heart transplantation is the gold-standard long-term treatment for medically refractive end-stage heart failure. However, suitable cardiac donors are scarce. Although donation after circulatory death has been used for kidney, liver, and lung transplantation, it is not used for heart transplantation. We report a case series of heart transplantations from donors after circulatory death., Methods: The recipients were patients at St Vincent's Hospital, Sydney, Australia. They received Maastricht category III controlled hearts donated after circulatory death from people younger than 40 years and with a maximum warm ischaemic time of 30 min. We retrieved four hearts through initial myocardial protection with supplemented cardioplegia and transferred to an Organ Care System (Transmedics) for preservation, resuscitation, and transportation to the recipient hospital., Findings: Three recipients (two men, one woman; mean age 52 years) with low transpulmonary gradients (<8 mm Hg) and without previous cardiac surgery received the transplants. Donor heart warm ischaemic times were 28 min, 25 min, and 22 min, with ex-vivo Organ Care System perfusion times of 257 min, 260 min, and 245 min. Arteriovenous lactate values at the start of perfusion were 8·3-8·1 mmol/L for patient 1, 6·79-6·48 mmol/L for patient 2, and 7·6-7·4 mmol/L for patient 3. End of perfusion lactate values were 3·6-3·6 mmol/L, 2·8-2·3 mmol/L, and 2·69-2·54 mmol/L, respectively, showing favourable lactate uptake. Two patients needed temporary mechanical support. All three recipients had normal cardiac function within a week of transplantation and are making a good recovery at 176, 91, and 77 days after transplantation., Interpretation: Strict limitations on donor eligibility, optimised myocardial protection, and use of a portable ex-vivo organ perfusion platform can enable successful, distantly procured orthotopic transplantation of hearts donated after circulatory death., Funding: NHMRC, John T Reid Charitable Trust, EVOS Trust Fund, Harry Windsor Trust Fund., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Continuous-flow left ventricular assist devices (CF-LVADs) improve functional capacity in patients with end-stage heart failure. Pump output can be increased by increased pump speed as well as changes in loading conditions., Methods: The effect of exercise on invasive hemodynamics was studied in two study protocols. The first examined exercise at fixed pump speed (n = 8) and the second with progressive pump speed increase (n = 11). Patients underwent simultaneous right-heart catheterization, mixed venous saturation, echocardiography and mean arterial pressure monitoring. Before exercise, a ramp speed study was performed in all patients. Patients then undertook symptom-limited supine bicycle exercise., Results: Upward titration of pump speed at rest (by 11.6 ± 8.6% from baseline) increased pump flow from 5.3 ± 1.0 to 6.3 ± 1.0 liters/min (18.9% increase, p < 0.001) and decreased pulmonary capillary wedge pressure (PCWP; 13.6 ± 5.4 to 8.9 ± 4.1 mm Hg, p < 0.001). Exercise increased pump flow to a similar extent as pump speed change alone (to 6.2 ± 1.0 liters/min, p < 0.001), but resulted in increased right- and left-heart filling pressures (right atrial pressure [RAP]: 16.6 ± 7.5 mm Hg, p < 0.001; PCWP 24.8 ± 6.7 mm Hg, p < 0.001). Concomitant pump speed increase with exercise enhanced the pump flow increase (to 7.0 ± 1.4 liters/min, p < 0.001) in Protocol 2, but did not alleviate the increase in pre-load (RAP: 20.5 ± 8.0 mm Hg, p = 0.07; PCWP: 26.8 ± 12.7 mm Hg; p = 0.47). Serum lactate and NT-proBNP levels increased significantly with exercise., Conclusions: Pump flow increases with up-titration of pump speed and with exercise. Although increased pump speed decreases filling pressures at rest, the benefit is not seen with exercise despite concurrent up-titration of pump speed., (Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.)

Objectives: The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs)., Background: Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return., Methods: Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded., Results: Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p < 0.0001 analysis of variance). With active ankle flexion, LVAD flow returned to baseline. There was no significant change in flow with a 20° head-down tilt with or without ankle flexion exercise. There were no suction events., Conclusions: Centrifugal cfLVAD flows are not significantly affected by changes in heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Owing to persisting donor shortages, the use of "marginal hearts" has increased. Because patients who receive a marginal heart may require hemodynamic support in the early post-operative period, extracorporeal membrane oxygenation (ECMO) may be used until recovery of acute graft dysfunction., Methods: A retrospective file review of 124 primary adult heart transplant patients from 2003 to 2008 was conducted. We compared 17 patients who received post-transplant ECMO support with 107 transplant recipients without ECMO. Donor and recipient pre-transplant, intra-operative, and post-transplant clinical variables to 6 months after transplant were compared., Results: Pre-operative demographics of the 2 groups were similar. Eight (47%) of the patients in the ECMO group received marginal donor hearts, compared with 1 (1%) in the non-ECMO group (p < 0.05). There were 3 early deaths in the ECMO group (2 of whom had received optimal donor hearts), resulting in lower Day 30 ECMO survival of 82.4% vs 100% for non-ECMO, respectively (p < 0.001), and 6-month survival of 82.4% vs 95.6%, respectively (p < 0.02). Most of the difference in survival was in patients who required salvage ECMO despite normal pre-transplant donor LV function. The rate of early dialysis was higher in the ECMO group, at 18% vs 6% at Day 3, but there was no difference between the 2 groups by Day 7. Pre-discharge ventricular function was normal in all discharged ECMO patients and all but 1 non-ECMO patient. ECMO patients had a longer intensive care unit stay (8.9 ± 3.4 vs 4.8 ± 5.4 days, p < 0.005), but there was a slightly shorter ward stay, resulting in a similar overall hospitalization length of stay (22.9 ± 8.3 vs 25.1 ± 25.2 days)., Conclusions: ECMO allows for salvage of acute graft dysfunction and may allow use of marginal donor hearts. Survival rates are lower in patients who require ECMO compared with optimal donors, but early cardiac dysfunction normalizes in most without long-term cardiac or renal sequelae. Despite longer ventilation times, overall hospitalization is not prolonged., (Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.)

Background: As a major provider of health care for racial and ethnic minority groups, the federal government has affirmed its commitment to the elimination of health disparities. Although numerous studies have examined health care disparities in various federal systems of care, few have examined these issues within TRICARE, the Department of Defense (DoDJ's program for providing health care coverage to members of the uniformed services and their dependents., Methods: This study provides an exploratory analysis examining apparent disparities in health status, access to and satisfaction with care, and use of preventive care using the 2007 Health Care Survey of DoD Beneficiaries. Analyses compare outcomes by race/ethnicity and between TRICARE beneficiaries and national norms derived from the National Consumer Assessment of Health Plans Study Benchmarking Database and the National Healthcare Disparities Report, and are stratified by duty status., Results: Compared to black non-Hispanics, a higher proportion of white non-Hispanic active-duty and retiree TRICARE beneficiaries reported good to excellent health status. However, on most measures, we found no differences between white non-Hispanic beneficiaries and members of racial/ethnic groups. When differences did exist, minority populations were likely to report better access to and use of services than whites., Conclusions: Although health disparities exist in health status and some measures of preventive care, black non-Hispanics and Hispanics often receive more equitable care under TRICARE than in the nation as a whole. These findings suggest the need to explore the characteristics of TRICARE that may be associated with more-favorable outcomes for racial and ethnic minority groups.

The structure and physical properties of solloids (surfactant aggregates adsorbed on surfaces) adsorbed on particles are of general interest. The relationship between solloid structure and properties of hexadecyltrimethylammonium bromide (HTAB), cetylpyridinium chloride (CPC) and cetylpyridinium salicylate (CPS) adsorbed on silica particles was studied by electron paramagnetic resonance (EPR) spectroscopy using the spin-probes peroxylaminedisulfonate (PADS) and 4-[N,N-dimethyl-N-(n-hexadecyl)ammonium]-2,2,6,6-tetramethylpiperidin yl-N-oxy bromide (HTAB*). Using HTAB* incorporated in HTAB, CPC and CPC solloids and comparing the results to those in micelles, it was determined that for silica around pH 4 the solloids are very similar in properties to the micelles. This is consistent with a linear solvation-energy relationship (LSER) analysis of solute equilibration data which indicates that at pH 5 HTAB solloids have similar properties to HTAB micelles. The PADS spin-probe appears to be more sensitive to changes in the properties of the double layer, and substantial differences were observed between HTAB, CPC and CPS and as a function of HTAB concentration for HTAB solloids on silica.