Isolation of recombinant apolipoprotein E4 N-terminal domain by foam fractionation.

Apolipoprotein (apo) E functions in lipoprotein metabolism as a low density lipoprotein receptor ligand. ApoE is comprised of two structural domains, a 22 kDa N-terminal (NT) domain that adopts a helix bundle conformation and a 10 kDa C-terminal domain with strong lipid binding affinity. The NT domain is capable of transforming aqueous phospholipid dispersions into discoidal reconstituted high density lipoprotein (rHDL) particles. Given the utility of apoE-NT as a structural component of rHDL, expression studies were conducted. A plasmid construct encoding a pelB leader sequence fused to the N-terminus of human apoE4 (residues 1-183) was transformed into Escherichia coli. Upon expression, the fusion protein is directed to the periplasmic space where leader peptidase cleaves the pelB sequence, generating mature apoE4-NT. In shaker flask expression cultures, apoE4-NT escapes the bacteria and accumulates in the medium. In a bioreactor setting, however, apoE4-NT was found to combine with gas and liquid components in the culture medium to generate large quantities of foam. When this foam was collected in an external vessel and collapsed into a liquid foamate, analysis revealed that apoE4-NT was the sole major protein present. The product protein was further isolated by heparin affinity chromatography (60-80 mg/liter bacterial culture), shown to be active in rHDL formulation, and documented to serve as an acceptor of effluxed cellular cholesterol. Thus, foam fractionation provides a streamlined process to produce recombinant apoE4-NT for biotechnology applications.

Parsimony and the rank of a flattening matrix.

The standard models of sequence evolution on a tree determine probabilities for every character or site pattern. A flattening is an arrangement of these probabilities into a matrix, with rows corresponding to all possible site patterns for one set A of taxa and columns corresponding to all site patterns for another set B of taxa. Flattenings have been used to prove difficult results relating to phylogenetic invariants and consistency and also form the basis of several methods of phylogenetic inference. We prove that the rank of the flattening equals [Formula: see text], where r is the number of states and [Formula: see text] is the minimum size of a vertex cut separating A from B. When T is binary the rank of the flattening equals [Formula: see text] where [Formula: see text] equals the parsimony length of the binary character separating A and B. We provide a direct proof that requires little more than undergraduate algebra, but note that the formula could also be derived from work by Casanellas and Fernández-Sánchez (2011) on phylogenetic invariants.

Risk factors and prognostic implications of diagnosis of cancer within 30 days after an emergency hospital admission (emergency presentation): an International Cancer Benchmarking Partnership (ICBP) population-based study.

BACKGROUND: Greater understanding of international cancer survival differences is needed. We aimed to identify predictors and consequences of cancer diagnosis through emergency presentation in different international jurisdictions in six high-income countries. METHODS: Using a federated analysis model, in this cross-sectional population-based study, we analysed cancer registration and linked hospital admissions data from 14 jurisdictions in six countries (Australia, Canada, Denmark, New Zealand, Norway, and the UK), including patients with primary diagnosis of invasive oesophageal, stomach, colon, rectal, liver, pancreatic, lung, or ovarian cancer during study periods from Jan 1, 2012, to Dec 31, 2017. Data were collected on cancer site, age group, sex, year of diagnosis, and stage at diagnosis. Emergency presentation was defined as diagnosis of cancer within 30 days after an emergency hospital admission. Using logistic regression, we examined variables associated with emergency presentation and associations between emergency presentation and short-term mortality. We meta-analysed estimates across jurisdictions and explored jurisdiction-level associations between cancer survival and the percentage of patients diagnosed as emergencies. FINDINGS: In 857 068 patients across 14 jurisdictions, considering all of the eight cancer sites together, the percentage of diagnoses through emergency presentation ranged from 24·0% (9165 of 38 212 patients) to 42·5% (12 238 of 28 794 patients). There was consistently large variation in the percentage of emergency presentations by cancer site across jurisdictions. Pancreatic cancer diagnoses had the highest percentage of emergency presentations on average overall (46·1% [30 972 of 67 173 patients]), with the jurisdictional range being 34·1% (1083 of 3172 patients) to 60·4% (1317 of 2182 patients). Rectal cancer had the lowest percentage of emergency presentations on average overall (12·1% [10 051 of 83 325 patients]), with a jurisdictional range of 9·1% (403 of 4438 patients) to 19·8% (643 of 3247 patients). Across the jurisdictions, older age (ie, 75-84 years and 85 years or older, compared with younger patients) and advanced stage at diagnosis compared with non-advanced stage were consistently associated with increased emergency presentation risk, with the percentage of emergency presentations being highest in the oldest age group (85 years or older) for 110 (98%) of 112 jurisdiction-cancer site strata, and in the most advanced (distant spread) stage category for 98 (97%) of 101 jurisdiction-cancer site strata with available information. Across the jurisdictions, and despite heterogeneity in association size (I2=93%), emergency presenters consistently had substantially greater risk of 12-month mortality than non-emergency presenters (odds ratio >1·9 for 112 [100%] of 112 jurisdiction-cancer site strata, with the minimum lower bound of the related 95% CIs being 1·26). There were negative associations between jurisdiction-level percentage of emergency presentations and jurisdiction-level 1-year survival for colon, stomach, lung, liver, pancreatic, and ovarian cancer, with a 10% increase in percentage of emergency presentations in a jurisdiction being associated with a decrease in 1-year net survival of between 2·5% (95% CI 0·28-4·7) and 7·0% (1·2-13·0). INTERPRETATION: Internationally, notable proportions of patients with cancer are diagnosed through emergency presentation. Specific types of cancer, older age, and advanced stage at diagnosis are consistently associated with an increased risk of emergency presentation, which strongly predicts worse prognosis and probably contributes to international differences in cancer survival. Monitoring emergency presentations, and identifying and acting on contributing behavioural and health-care factors, is a global priority for cancer control. FUNDING: Canadian Partnership Against Cancer; Cancer Council Victoria; Cancer Institute New South Wales; Cancer Research UK; Danish Cancer Society; National Cancer Registry Ireland; The Cancer Society of New Zealand; National Health Service England; Norwegian Cancer Society; Public Health Agency Northern Ireland, on behalf of the Northern Ireland Cancer Registry; the Scottish Government; Western Australia Department of Health; and Wales Cancer Network.

Impact of the COVID-19 pandemic on emergency hospital cancer admissions in a UK region.

BACKGROUND: The pandemic disrupted society and health services through lockdowns and resource reallocation to care for COVID-19 patients. Reductions in numbers of cancer patients having surgery, being diagnosed pathologically or via 2-week wait, and screening programs pauses have been described. The effect on emergency presentation, which represents an acute episode with poor outcomes, has not been investigated. This study explored the pandemic's impact on emergency hospital admissions for cancer patients in a UK region. METHODS: Hospital discharge data for cancer patients in Northern Ireland, which included route to admission, were analysed for the pandemic era in 2020 compared to averages for March to December 2017-2019, focusing on volume and route of emergency admissions by demography and tumour site. FINDINGS: Compared with the pre-pandemic era, the number of cancer emergency admissions fell by 12·3% in 2020. Emergency admissions for cancer were significantly reduced when COVID-19 levels were highest (- 18·5% in April and - 16.8% in October). Females (- 15·8%), urban residents (- 13·2%), and age groups 0 to 49 and 65-74 years old (- 17%) experienced the largest decreases as did those with haematological (- 14·7%), brain and CNS (- 27·9%), and lung cancers(- 14·3%). Significant reductions in referrals from outpatient departments (- 51%) and primary care (- 43%) (p < 0·001) were counterbalanced by admissions from other routes including confirmed or suspected COVID-19 infection (increase 83·6%). INTERPRETATION: Reductions in emergency admissions, and pathologically diagnosed cancers, as reported by the Northern Ireland Cancer Registry (NICR), indicate undiagnosed patients in the community which has implications for future workloads and survival. Data suggest undiagnosed cases may be higher for haematological, brain and CNS, and lung cancers and among females. Efforts should be made to encourage people with symptoms to present for diagnosis or reassurance. FUNDING: The NICR is funded by the Public Health Agency of Northern Ireland. This work was supported by Macmillan Cancer Support and uses data collected by health services as part of their care and support functions.

Survival of cancer patients with pre-existing heart disease.

BACKGROUND: While cancer outcomes have improved over time, in Northern Ireland they continue to lag behind those of many other developed economies. The role of comorbid conditions has been suggested as a potential contributory factor in this but issues of data comparability across jurisdictions has inhibited efforts to explore relationships. We use data from a single jurisdiction of the UK using data from - the Northern Ireland Cancer Registry (NICR), to examine the association between mortality (all-cause and cancer specific) and pre-existing cardiovascular diseases among patients with cancer. MATERIALS AND METHODS: All patients diagnosed with cancer (excluding non-melanoma skin cancer) between 2011 and 2014 were identified from Registry records. Those with a pre-existing diagnosis of cardiovascular diseases were identified by record linkage with patient hospital discharge data using ICD10 codes. Survival following diagnosis was examined using descriptive statistics and Cox proportional hazards regression analyses. Analyses examined all-cause mortality and cancer specific mortality for lung, colorectal, breast and prostate cancer. As well as cardiovascular diseases, regression models controlled for age, gender (where appropriate), deprivation (as quintiles), stage at diagnosis and other comorbidities. RESULTS: Almost 35,000 incident cancer cases were diagnosed during the study period of which approximately 23% had a prior heart condition. The pan-cancer hazard ratio for death in the presence of pre-existing cardiovascular diseases was 1.28 (95% CI: 1.18-1.40). All-cause and cancer specific mortality was higher for patients with cardiovascular diseases across lung, female breast, prostate and colorectal cancer groups after controlling for age, gender (where appropriate), deprivation (as quintiles), stage at diagnosis and other comorbidities. CONCLUSION: Pre-existing morbidity may restrict the treatment of cancer for many patients. In this cohort, cancer patients with pre-existing cardiovascular diseases had poorer outcomes than those without cardiovascular diseases. A high prevalence of cardiovascular diseases may contribute to poorer cancer outcomes at a national level.

Bayesian Inference of Species Trees using Diffusion Models.

We describe a new and computationally efficient Bayesian methodology for inferring species trees and demographics from unlinked binary markers. Likelihood calculations are carried out using diffusion models of allele frequency dynamics combined with novel numerical algorithms. The diffusion approach allows for analysis of data sets containing hundreds or thousands of individuals. The method, which we call Snapper, has been implemented as part of the BEAST2 package. We conducted simulation experiments to assess numerical error, computational requirements, and accuracy recovering known model parameters. A reanalysis of soybean SNP data demonstrates that the models implemented in Snapp and Snapper can be difficult to distinguish in practice, a characteristic which we tested with further simulations. We demonstrate the scale of analysis possible using a SNP data set sampled from 399 fresh water turtles in 41 populations. [Bayesian inference; diffusion models; multi-species coalescent; SNP data; species trees; spectral methods.].

Inequalities in the decline and recovery of pathological cancer diagnoses during the first six months of the COVID-19 pandemic: a population-based study.

BACKGROUND: The restructuring of healthcare systems to cope with the demands of the COVID-19 pandemic has led to a reduction in clinical services such as cancer screening and diagnostics. METHODS: Data from the four Northern Ireland pathology laboratories were used to assess trends in pathological cancer diagnoses from 1st March to 12th September 2020 overall and by cancer site, sex and age. These trends were compared to the same timeframe from 2017 to 2019. RESULTS: Between 1st March and 12th September 2020, there was a 23% reduction in cancer diagnoses compared to the same time period in the preceding 3 years. Although some recovery occurred in August and September 2020, this revealed inequalities across certain patient groups. Pathological diagnoses of lung, prostate and gynaecological malignancies remained well below pre-pandemic levels. Males and younger/middle-aged adults, particularly the 50-59-year-old patient group, also lagged behind other population demographic groups in terms of returning to expected numbers of pathological cancer diagnoses. CONCLUSIONS: There is a critical need to protect cancer diagnostic services in the ongoing pandemic to facilitate timely investigation of potential cancer cases. Targeted public health campaigns may be needed to reduce emerging inequalities in cancer diagnoses as the COVID-19 pandemic continues.

V-Spline: An Adaptive Smoothing Spline for Trajectory Reconstruction.

Trajectory reconstruction is the process of inferring the path of a moving object between successive observations. In this paper, we propose a smoothing spline-which we name the V-spline-that incorporates position and velocity information and a penalty term that controls acceleration. We introduce an adaptive V-spline designed to control the impact of irregularly sampled observations and noisy velocity measurements. A cross-validation scheme for estimating the V-spline parameters is proposed, and, in simulation studies, the V-spline shows superior performance to existing methods. Finally, an application of the V-spline to vehicle trajectory reconstruction in two dimensions is given, in which the penalty term is allowed to further depend on known operational characteristics of the vehicle.

Solutions of the Multivariate Inverse Frobenius-Perron Problem.

We address the inverse Frobenius-Perron problem: given a prescribed target distribution ρ, find a deterministic map M such that iterations of M tend to ρ in distribution. We show that all solutions may be written in terms of a factorization that combines the forward and inverse Rosenblatt transformations with a uniform map; that is, a map under which the uniform distribution on the d-dimensional hypercube is invariant. Indeed, every solution is equivalent to the choice of a uniform map. We motivate this factorization via one-dimensional examples, and then use the factorization to present solutions in one and two dimensions induced by a range of uniform maps.

Dye binding assay reveals doxorubicin preference for DNA versus cardiolipin.

Doxorubicin (DOX) is a potent anticancer agent that binds both DNA and cardiolipin (CL). To investigate DOX binding to CL versus DNA, aqueous soluble, CL-enriched nanoparticles, termed nanodisks (ND), were employed. Upon incubation with CL-ND, but not with phosphatidylcholine ND, DOX binding was detected. DOX binding to CL-ND was sensitive to buffer pH and ionic strength. To investigate if a DOX binding preference for DNA versus CL-ND exists, an agarose gel-based dye binding assay was developed. Under conditions wherein the commercial fluorescent dye, GelRed, detects a 636 bp DNA template following electrophoresis, DOX staining failed to visualize this DNA band. Incubation of the template DNA with DOX prior to electrophoresis resulted in a DOX concentration-dependent attenuation of GelRed staining intensity. When the template DNA was pre-incubated with equivalent amounts of free DOX or DOX-CL-ND, no differences in the extent of GelRed staining intensity attenuation were noted. When DOX was incubated with DNA alone, or a mixture of DNA and CL-ND, the extent of DOX-induced GelRed staining intensity attenuation was equivalent. Thus, DOX has a binding preference for DNA versus CL and, moreover, DOX-CL-ND offer a potential strategy to prevent DOX-induced cardiotoxicity while not affecting its affinity for DNA.

Modeling low-frequency vibration in light-weight timber floor/ceiling systems.

Producing practical designs for light-weight timber-framed structures that achieve high sound isolation remains a challenging task, in part because of the lack of models that can accurately predict the sound transmission through proposed designs. This work develops detailed modeling of structural vibration in timber floor/ceiling systems, from which sound transmission in the low-frequency regime (10-150 Hz) can be computed, as a design tool for producing practical timber floor/ceiling details that achieve high isolation for low-frequency sound. The mathematical model uses a variational formulation that enables straightforward modeling of complex composite structures, and introduces the notion of coupling layers to model the movement between joined materials that occurs with practical bonding methods, thereby improving on existing models that assume either perfectly bonded or perfectly slipping interfaces. The composite model structure is assembled only at the computational step, giving an efficient computational scheme that also fits well into the design-development cycle. Results from a parallel experimental program are used to validate the model and to determine effective coupling and damping parameters. The influence of coupling parameters is shown for an example floor, demonstrating that finite slippage at joints is required for the model to predict low-frequency vibration in practical constructions.

Foam fractionation studies of recombinant human apolipoprotein A-I.

Apolipoprotein A-I (apoA-I), the primary protein component of plasma high-density lipoproteins (HDL), is comprised of two structural regions, an N-terminal amphipathic α-helix bundle domain (residues 1-184) and a hydrophobic C-terminal domain (residues 185-243). When a recombinant fusion protein construct [bacterial pelB leader sequence - human apoA-I (1-243)] was expressed in Escherichia coli shaker flask cultures, apoA-I was recovered in the cell lysate. By contrast, when the C-terminal domain was deleted from the construct, large amounts of the truncated protein, apoA-I (1-184), were recovered in the culture medium. Consequently, following pelB leader sequence cleavage in the E. coli periplasmic space, apoA-I (1-184) was secreted from the bacteria. When the pelB-apoA-I (1-184) fusion construct was expressed in a 5 L bioreactor, substantial foam production (~30 L) occurred. Upon foam collection and collapse into a liquid foamate, SDS-PAGE revealed that apoA-I (1-184) was the sole major protein present. Incubation of apoA-I (1-184) with phospholipid vesicles yielded reconstituted HDL (rHDL) particles that were similar in size and cholesterol efflux capacity to those generated with full-length apoA-I. Mass spectrometry analysis confirmed that pelB leader sequence cleavage occurred and that foam fractionation did not result in unwanted protein modifications. The facile nature and scalability of bioreactor-based apolipoprotein foam fractionation provide a novel means to generate a versatile rHDL scaffold protein.

Alkaline surface treatment and time-resolved reading of mn-doped nanocrystal signal transducer for enhanced bioassay sensitivity.

Recently, Mn-doped semiconductor nanocrystals (NCs) with high brightness, long lifetimes, and low-energy excitation are emerging for time-resolved luminescence biosensing/imaging. Following our previous work on Mn-doped NCs, in this work we developed poly(styrene-co-maleic anhydride) (PSMA)-encapsulated Mn-doped AgZnInS/ZnS NCs as signal transducers for immunoassay of capsular polysaccharide (CPS), a surface antigen and also a biomarker of Burkholderia pseudomallei which causes a fatal disease called melioidosis. To enhance the assay sensitivity, a surface treatment for PSMA-encapsulated NCs (NC-probes) was performed to promote the presence of carboxyl groups that help conjugate more anti-CPS antibodies to the surface of NC-probes and thus enhance bioassay signals. Meanwhile, time-resolved reading on the luminescence of NC-probes was adopted to minimize the assay background autofluorescence. Both strategies essentially enhance the assay signal-to-background ratio (or equivalently the assay sensitivity) by increasing the signal and decreasing the background, respectively. Through performing and comparing immunoassays with different NC-probes (with and without surface treatment) and different signal reading methods (time-resolved reading and non-time-resolved reading), it was proven that the immunoassay adopting surface-treated NC-probes and time-resolved reading achieved a lower limit-of-detection (LOD) than the ones adopting non-surface-treated NC-probes or non-time-resolved reading. Moreover, the achieved LOD is comparable to the LOD of immunoassay using enzyme horseradish peroxidase as a signal transducer.

Formulation and Characterization of Bioactive Agent Containing Nanodisks.

The term nanodisk refers to a discrete type of nanoparticle comprised of a bilayer forming lipid, a scaffold protein, and an integrated bioactive agent. Nanodisks are organized as a disk-shaped lipid bilayer whose perimeter is circumscribed by the scaffold protein, usually a member of the exchangeable apolipoprotein family. Numerous hydrophobic bioactive agents have been efficiently solubilized in nanodisks by their integration into the hydrophobic milieu of the particle's lipid bilayer, yielding a largely homogenous population of particles in the range of 10-20 nm in diameter. The formulation of nanodisks requires a precise ratio of individual components, an appropriate sequential addition of each component, followed by bath sonication of the formulation mixture. The amphipathic scaffold protein spontaneously contacts and reorganizes the dispersed bilayer forming lipid/bioactive agent mixture to form a discrete, homogeneous population of nanodisk particles. During this process, the reaction mixture transitions from an opaque, turbid appearance to a clarified sample that, when fully optimized, yields no precipitate upon centrifugation. Characterization studies involve the determination of bioactive agent solubilization efficiency, electron microscopy, gel filtration chromatography, ultraviolet visible (UV/Vis) absorbance spectroscopy, and/or fluorescence spectroscopy. This is normally followed by an investigation of biological activity using cultured cells or mice. In the case of nanodisks harboring an antibiotic (i.e., the macrolide polyene antibiotic amphotericin B), their ability to inhibit the growth of yeast or fungi as a function of concentration or time can be measured. The relative ease of formulation, versatility with respect to component parts, nanoscale particle size, inherent stability, and aqueous solubility permits myriad in vitro and in vivo applications of nanodisk technology. In the present article, we describe a general methodology to formulate and characterize nanodisks containing amphotericin B as the hydrophobic bioactive agent.

Studies of the cardiolipin interactome.

Cardiolipin (CL) is a unique phospholipid that is fundamental to the structure and function of the highly curved cristae membranes of mitochondria. Given its distinctive cone-shaped molecular architecture, CL induces negative membrane curvature in a bilayer setting. Another key feature of CL is its intrinsic ability to interact with various ligands, including cytochrome c, the anti-neoplastic anthracycline, doxorubicin, and the divalent cation, calcium. Although these, and other, binding interactions exert profound effects on mitochondrial and cellular function, they are difficult to study in intact mitochondria. Whereas liposomes provide a potential model membrane system, their relatively large size, limited ability to accommodate CL and the presence of an inaccessible interior bilayer leaflet, make these structures suboptimal. The discovery that CL can be formulated into aqueous soluble, reconstituted high density lipoprotein particles, termed nanodisks (ND), provides an alternative model membrane system. Comprised solely of CL and an apolipoprotein scaffold, CL-ND exist as a disk-shaped phospholipid bilayer whose perimeter is stabilized by contact with the scaffold protein. In these nanoscale particles, both leaflets of the bilayer are solvent accessible, an advantage for studies of ligand interactions. Recent experiments employing CL-ND have yielded novel insight into apoptosis, cardiotoxicity and CL-dependent bilayer to non-bilayer transitions.

Foam fractionation of a recombinant biosurfactant apolipoprotein.

Locusta migratoria apolipophorin III (apoLp-III) possesses the ability to exist as a water soluble amphipathic α-helix bundle and a lipid surface seeking apolipoprotein. The intrinsic ability of apoLp-III to transform phospholipid vesicles into reconstituted discoidal high-density lipoproteins (rHDL) has led to myriad applications. To improve the yield of recombinant apoLp-III, studies were performed in a bioreactor. Induction of apoLp-III expression generated a protein product that is secreted from E. coli into the culture medium. Interaction of apoLp-III with gas and liquid components in media produced large quantities of thick foam. A continuous foam fractionation process yielded a foamate containing apoLp-III as the sole major protein component. The yield of recombinant apoLp-III was ~0.2 g / liter bacterial culture. Mass spectrometry analysis verified the identity of the target protein and indicated no modifications or changes to apoLp-III occurred as a result of foam fractionation. The functional ability of apoLp-III to induce rHDL formation was evaluated by incubating foam fractionated apoLp-III with phosphatidylcholine vesicles. FPLC size exclusion chromatography revealed a single major population of particles in the size range of rHDL. The results described offer a novel approach to bioreactor-based apoLp-III production that takes advantage of its intrinsic biosurfactant properties.

Lutein nanodisks protect human retinal pigment epithelial cells from UV light-induced damage.

The hydrophobic carotenoid, lutein, was conferred with aqueous solubility upon formulation into reconstituted discoidal high density lipoprotein particles, termed lutein nanodisks (ND). When formulated with phosphatidylcholine (PC), apolipoprotein (apo) A-I and lutein (formulation ratio = 5 mg PC/2 mg apoA-I/1 mg lutein), lutein solubilization efficiency in phosphate buffered saline (PBS) was ~90%. The UV/Vis absorbance maxima for lutein ND in PBS were red shifted by 6-13 nm versus the corresponding lutein absorbance maxima in ethanol. FPLC gel filtration chromatography gave rise to a single major absorbance peak in the size range of ND. Incubation of cultured ARPE-19 cells with lutein ND resulted in lutein uptake, as determined by HPLC analysis of cell extracts. Compared to control incubations, ARPE-19 cells incubated with lutein ND were protected from UV light-induced loss of cell viability. Consistent with this, reactive oxygen species generation, induced by exposure to UV irradiation, was lower in lutein-enriched cells than in control cells. Thus, uptake of ND-associated lutein protects ARPE-19 cells from UV light-induced damage. Taken together, the data indicate ND provide an aqueous lutein delivery vehicle for biotechnological or therapeutic applications.

Cardiolipin nanodisks confer protection against doxorubicin-induced mitochondrial dysfunction.

Doxorubicin (DOX) is an aqueous soluble anthracycline therapeutic widely used in cancer treatment. Although DOX anti-cancer activity is dose-dependent, increased dosage enhances the risk of cardiotoxicity. Despite intensive investigation, the molecular basis of this undesirable side effect has yet to be established. In addition to serving as a DNA intercalation agent, DOX is known to bind to the signature mitochondrial phospholipid, cardiolipin (CL). Consistent with this, DOX associates with aqueous soluble nanoparticles, termed nanodisks (ND), comprised solely of CL and an apolipoprotein scaffold. Fluorescence microscopy analysis revealed that DOX uptake, and targeting to the nucleus of cultured hepatocarcinoma (HepG2) or breast cancer (MCF7) cells, was unaffected by its association with CL-ND. Subsequent studies revealed that free DOX and DOX-CL-ND were equivalent in terms of growth inhibition activity in both cell lines. By contrast, in studies with H9C2 cardiomyocytes, DOX-CL-ND induced a lesser concentration-dependent decline in cell viability than free DOX. Whereas incubation of H9C2 cardiomyocytes with free DOX caused a steep decline in maximal oxygen consumption rate, DOX-CL-ND treated cells were largely unaffected. The data indicate that association of DOX with CL-ND does not diminish its cancer cell growth inhibition activity yet confers protection to cardiomyocytes from DOX-induced effects on aerobic respiration. This study illustrates that interaction with CL plays a role in DOX-induced mitochondrial dysfunction and suggests CL-ND provide a tool for investigating the mechanistic basis of DOX-induced cardiotoxicity.

MCMC estimation of Markov models for ion channels.

Ion channels are characterized by inherently stochastic behavior which can be represented by continuous-time Markov models (CTMM). Although methods for collecting data from single ion channels are available, translating a time series of open and closed channels to a CTMM remains a challenge. Bayesian statistics combined with Markov chain Monte Carlo (MCMC) sampling provide means for estimating the rate constants of a CTMM directly from single channel data. In this article, different approaches for the MCMC sampling of Markov models are combined. This method, new to our knowledge, detects overparameterizations and gives more accurate results than existing MCMC methods. It shows similar performance as QuB-MIL, which indicates that it also compares well with maximum likelihood estimators. Data collected from an inositol trisphosphate receptor is used to demonstrate how the best model for a given data set can be found in practice.