Combination treatments including the small-interfering RNA JNJ-3989 induce rapid and sometimes prolonged viral responses in patients with CHB.

BACKGROUND & AIMS: RNA interference therapy has been shown to reduce hepatitis B surface antigen (HBsAg) levels in preclinical models, which could confer functional cure in patients with chronic hepatitis B. This phase IIa trial (ClinicalTrials.gov Identifier: NCT03365947) assessed the safety and efficacy of the small-interfering RNA JNJ-73763989 (JNJ-3989) plus a nucleos(t)ide analogue (NA), with/without the capsid assembly modulator JNJ-56136379 (JNJ-6379) in patients with chronic hepatitis B. METHODS: Treatment-naïve and NA-suppressed patients received 3 subcutaneous JNJ-3989 doses every week (QW; 100, 200, or 300 mg), 2 weeks (Q2W; 100 mg) or 4 weeks (Q4W; 25, 50, 100, 200, 300, or 400 mg), or JNJ-3989 Q4W (200 mg) plus oral JNJ-6379 250 mg daily for 12 weeks. Patients received NAs throughout. RESULTS: Eighty-four patients were recruited. All treatments were well tolerated, with all 5 serious adverse events considered unrelated to study drugs. JNJ-3989 100 to 400 mg Q4W resulted in HBsAg reductions ≥1 log10 IU/ml from baseline in 39/40 (97.5%) patients at the nadir. All patients receiving the triple combination (n = 12) had HBsAg reductions ≥1 log10 IU/ml from baseline at the nadir. HBsAg reductions were similar for HBeAg-positive (n = 21) and HBeAg-negative (n = 47) patients in all JNJ-3989 Q4W treatment arms, including the triple combination (n = 68). Smaller HBsAg reductions were seen with 25 mg (n = 8) and 50 mg (n = 8) than with 100 to 400 mg (n = 40). Shorter dosing intervals (QW [n = 12] and Q2W [n = 4]) did not improve response vs. Q4W dosing. HBsAg reductions ≥1 log10 IU/ml from baseline persisted in 38% of patients 336 days after the last JNJ-3989 dose. CONCLUSIONS: JNJ-3989 plus an NA, with/without JNJ-6379, was well tolerated and resulted in HBsAg reductions up to 336 days after the last JNJ-3989 Q4W dose. CLINICAL TRIAL NUMBER: NCT03365947. LAY SUMMARY: Hepatitis B virus affects people's livers and produces particles called hepatitis B surface antigen (HBsAg) that damage a person's liver and can help the virus infect a person for a long time, known as chronic hepatitis B (CHB). In this study, a new treatment called JNJ-3989 was assessed (in combination with normal treatment known as nucleos(t)ide analogues), for its safety and effectiveness in reducing the number of HBsAg particles in people with CHB. The results of this study showed that treatment with JNJ-3989 could be safe for people with CHB, lowered their HBsAg levels, and kept HBsAg levels lowered for 336 days in 38% of patients after receiving their last dose of JNJ-3989.

Mean HBsAg decline at week 24 of PEG-IFN-based treatment predicts subsequent rate of HBsAg clearance - suggesting a valuable endpoint for early development HBV trials.

Earlier identification of potentially efficacious treatments in early development trials requires on-treatment response markers. We hypothesized that mean week 12 or 24 HBsAg decline could be a useful marker for subsequent off-treatment sustained HBsAg clearance at the treatment arm level in HBV trials. We used individual patient data from the studies HBV 9901 (peginterferon [PEG-IFN] versus PEG-IFN+lamivudine for HBeAg-positive CHB), PARC (PEG-IFN±ribavirin for HBeAg-negative CHB) and published data from 0149 (PEG-IFN±tenofovir for HBeAg-positive and HBeAg-negative CHB) and LIRA-B (PEG-IFN for HBeAg-positive CHB) to define the relationship between mean week HBsAg decline and HBsAg loss at 6 months post-treatment. A within-study comparison of HBsAg decline at weeks 12 and 24 between patients with or without HBsAg clearance was used to make projections beyond the observed HBsAg data. Across trials, a more pronounced mean HBsAg decline at week 24 was associated with higher rates of subsequent HBsAg loss. Mean HBsAg decline data at week 24 for patients with or without HBsAg clearance from HBV 9901 (4.3 vs 0.5), PARC (4.8 vs 0.3) and 0149 (PEG-IFN+TDF arm; 4.6 vs 0.6) were used to extrapolate this relationship beyond observed rates of HBsAg. An additional mean 1 log10 decline at week 24 versus a comparator arm is expected to translate into a 20%-30% increase in subsequent HBsAg loss during off-treatment follow-up. Observations were similar for week 12 data, but the relationship was less strong. Mean week 24 HBsAg decline predicts subsequent HBsAg loss and could be a valuable and useful early endpoint in HBV-treatment trials.

Evaluating futility of a binary clinical endpoint using early read-outs.

Interim analyses are routinely used to monitor accumulating data in clinical trials. When the objective of the interim analysis is to stop the trial if the trial is deemed futile, it must ideally be conducted as early as possible. In trials where the clinical endpoint of interest is only observed after a long follow-up, many enrolled patients may therefore have no information on the primary endpoint available at the time of the interim analysis. To facilitate earlier decision-making, one may incorporate early response data that are predictive for the primary endpoint (eg, an assessment of the primary endpoint at an earlier time) in the interim analysis. Most attention so far has been given to the development of interim test statistics that include such short-term endpoints, but not to decision procedures. Existing tests moreover perform poorly when the information is scarce, eg, due to rare events, when the cohort of patients with observed primary endpoint data is small, or when the short-term endpoint is a strong but imperfect predictor. In view of this, we develop an interim decision procedure based on the conditional power approach that utilizes the short-term and long-term binary endpoints in a framework that is expected to provide reliable inferences, even when the primary endpoint is only available for a few patients, and has the added advantage that it allows the use of historical information. The operational characteristics of the proposed procedure are evaluated for the phase III clinical trial that motivated this approach, using simulation studies.

Pseudo-tear appearance of the posterior tibiotalar ligament on fluid-sensitive sequences.

PURPOSE: This study aimed at studying the MR imaging appearance of the tibiotalar ligament in asymptomatic volunteers. MATERIALS AND METHODS: Fourty-two ankles were imaged on a 3T MR system using proton density weighted images with fat saturation (TR, 2969 ms; TE 30 ms; NA, 2; slice thickness, 2.5 mm). Subjects with acute ankle conditions or history of previous trauma were not included in the study group. Images were obtained in the three orthogonal planes. The posterior tibiotalar ligament was assessed on coronal imaging, by consensus of two radiologists. The signal intensity was recorded as isointense, hypointense, or hyperintense relative to muscle. The morphology of the ligament was classified as homogenous or striated. Descriptive statistics were obtained. RESULTS: There were 8 men and 14 women with a mean age of 24.7 years (range 19-43 years). The ligaments were classified as hyperintense in 30/42 (70%) of ankles and isointense in 9/42 (21%) of ankles. A striated appearance was seen in 34/42 (80%) of ankles. CONCLUSION: The posterior deep deltoid ligament is commonly hyperintense. It is usually striated although it can be homogeneously hyperintense. This appearance simulates a tear.

Potential Heating Effect in the Gravid Uterus by Using 3-T MR Imaging Protocols: Experimental Study in Miniature Pigs.

Purpose To determine the changes in temperature within the gravid miniature pig uterus during magnetic resonance (MR) imaging at 3 T. Materials and Methods The study received ethics committee approval for animal experimentation. Fiber-optic temperature sensors were inserted into the fetal brain, abdomen, bladder, and amniotic fluid of miniature pigs (second trimester, n = 2; third trimester, n = 2). In the first trimester (n = 2), the sensors were inserted only into the amniotic fluid (three sacs per miniature pig, for a total of six sacs). Imaging was performed with a 3-T MR imager by using different imaging protocols in a random order for animal, each lasting approximately 15 minutes. The first regimen consisted of common sequences used for human fetal MR examination, including normal specific absorption rate (SAR). The second regimen consisted of five low-SAR sequences, for which three gradient-echo sequences were interspersed with two diffusion-weighted imaging series. Finally, a high-SAR regimen maximized the radiofrequency energy deposition (constrained by the 2-W per kilogram of body weight SAR limitations) by using five single-shot turbo spin-echo sequences. Differences in temperature increases between the three regimens and between the three trimesters were evaluated by using one-way analysis of variance. The maximum cumulative temperature increase over 1 hour was also evaluated. Results Low-SAR regimens resulted in the lowest temperature increase (mean ± standard deviation, -0.03°C ± 0.20), normal regimens resulted in an intermediate increase (0.31°C ± 0.21), and high-SAR regimens resulted in the highest increase (0.56°C ± 0.20) (P < .0001). Mean temperature increase in the third trimester was 0.38°C ± 0.27, with no significant differences compared with the first (0.23°C ± 0.27) and second (0.25°C ± 0.32) trimesters (P = .07). The cumulative temperature increase over 1-hour imaging time with high SAR can reach 2.5°C. Conclusion In pregnant miniature pigs, the use of 3-T magnets for diagnostic MR imaging with normal SAR regimens does not lead to temperature increases above 1°C if imaging time is kept below 30 minutes. Longer imaging time, especially with high-SAR regimens, can lead to an increase of 2.5°C. (©) RSNA, 2015 Online supplemental material is available for this article.

Modelling of drug-induced QT-interval prolongation: estimation approaches and translational opportunities.

Safety pharmacology studies are performed to assess whether compounds may provoke severe arrhythmias (e.g. Torsades de Pointes, TdP) and sudden death in man. Although there is strong evidence that drugs inducing TdP in man prolong the QT interval in vivo and block the human ether-a-go-go-related gene (hERG) ion channel in vitro, not all drugs affecting the QT interval or the hERG will induce TdP. Nevertheless, QT-interval prolongation and hERG blockade currently represent the most accepted early risk biomarkers to deselect drugs. An extensive pharmacokinetic/pharmacodynamic (PK/PD) analysis is developed to understand moxifloxacin's-induced effects on the QT interval by comparing the relationship between results of an in vitro patch-clamp model to in vivo models. The frequentist and the fully Bayesian estimation procedures were compared and provided similar performances when the best model selected in NONMEM is subsequently implemented in WinBUGS, which guarantees a straightforward calculation of the probability of QT-interval prolongation greater than 2.5 % (10 ms). The use of the percent threshold to account for the intrinsic differences between species and a new calculation of the probability curve are introduced. The concentration providing the 50 % probability indicates that dogs are more sensitive than humans to QT-interval prolongation. However, based on the drug effect, a clear distinction between species cannot be made. An operational PK/PD model of agonism was used to investigate the relationship between effects on the hERG and QT-interval prolongation in dogs. The proposed analysis contributes to establish a translational relationship that could potentially reduce the need for thorough QT studies.

Distal insertions of the semimembranosus tendon: MR imaging with anatomic correlation.

OBJECTIVE: The purpose of this study is to investigate the distal insertions of the semimembranosus tendon with MR imaging, correlated with findings in cadavers. MATERIALS AND METHODS: Four fresh cadaveric specimens were studied with 3-T MR imaging. Sequences included proton density (PD) sequences (TE, 13; TR, 4957; FOV, 170 × 170; matrix, 424 × 413; NA, 2; slice thickness, 2.5 mm) in the axial, coronal, and sagittal planes and 3D fast field echo (FFE) sequences (TR 9.4; TE 6.9; FOV, 159 × 105; matrix, 200 × 211; NA, 2; slice thickness, 0.57 mm). One specimen was dissected and three specimens were sectioned with a bandsaw in the axial, coronal, and sagittal plane. The sections were photographed and correlated with MR images. To standardize the analysis, the semimembranosus muscle and tendon were assessed at seven levels for the axial sections, and at three levels for the coronal and sagittal sections. RESULTS: Anatomic dissection revealed six insertions of the distal semimembranosus tendon: direct arm, anterior arm, posterior oblique ligament extension, oblique popliteal ligament extension, distal tibial expansion (popliteus aponeurosis), and meniscal arm. Axial MR images showed five of six insertions: direct arm, anterior arm, oblique popliteal ligament extension, posterior oblique ligament extension, and distal tibial expansion. Sagittal MR images showed four of six insertions: direct arm, anterior arm, oblique popliteal ligament arm, and distal tibial expansion. Sagittal MR images were ideal for showing the direct arm insertion, but were less optimal than the axial images for showing the other insertions. The anterior arm was seen but volume averaging was present with the gracilis tendon. Coronal MR images optimally revealed the anterior arm, although magic angle artifact was present at its posterior aspect. The common semimembranosus tendon and meniscal arm were also well depicted. The division in anterior arm, direct arm, and oblique popliteal ligament arm was poorly seen on coronal images due to volume averaging. CONCLUSIONS: Although the anatomy of the distal semimembranosus tendon is complex, six different semimembranosus insertions can be identified on routine proton density and FFE sequences at 3 T. Analysis of images at defined levels in the three imaging planes simplifies MR interpretation of the anatomy of the distal semimembranosus tendon.

Mixed-effects beta regression for modeling continuous bounded outcome scores using NONMEM when data are not on the boundaries.

Beta regression models have been recommended for continuous bounded outcome scores that are often collected in clinical studies. Implementing beta regression in NONMEM presents difficulties since it does not provide gamma functions required by the beta distribution density function. The objective of the study was to implement mixed-effects beta regression models in NONMEM using Nemes' approximation to the gamma function and to evaluate the performance of the NONMEM implementation of mixed-effects beta regression in comparison to the commonly used SAS approach. Monte Carlo simulations were conducted to simulate continuous outcomes within an interval of (0, 70) based on a beta regression model in the context of Alzheimer's disease. Six samples per subject over a 3 years period were simulated at 0, 0.5, 1, 1.5, 2, and 3 years. One thousand trials were simulated and each trial had 250 subjects. The simulation-reestimation exercise indicated that the NONMEM implementation using Laplace and Nemes' approximations provided only slightly higher bias and relative RMSE (RRMSE) compared to the commonly used SAS approach with adaptive Gaussian quadrature and built-in gamma functions, i.e., the difference in bias and RRMSE for fixed-effect parameters, random effects on intercept, and the precision parameter were <1-3 %, while the difference in the random effects on the slope was <3-7 % under the studied simulation conditions. The mixed-effect beta regression model described the disease progression for the cognitive component of the Alzheimer's disease assessment scale from the Alzheimer's Disease Neuroimaging Initiative study. In conclusion, with Nemes' approximation of the gamma function, NONMEM provided comparable estimates to those from SAS for both fixed and random-effect parameters. In addition, the NONMEM run time for the mixed beta regression models appeared to be much shorter compared to SAS, i.e., 1-2 versus 20-40 s for the model and data used in the manuscript.

A cross-sectional case-control study on the structural connectome in recovered hospitalized COVID-19 patients.

COVID-19 can induce neurological sequelae, negatively affecting the quality of life. Unravelling this illness's impact on structural brain connectivity, white-matter microstructure (WMM), and cognitive performance may help elucidate its implications. This cross-sectional study aimed to investigate differences in these factors between former hospitalised COVID-19 patients (COV) and healthy controls. Group differences in structural brain connectivity were explored using Welch-two sample t-tests and two-sample Mann-Whitney U tests. Multivariate linear models were constructed (one per region) to examine fixel-based group differences. Differences in cognitive performance between groups were investigated using Wilcoxon Rank Sum tests. Possible effects of bundle-specific FD measures on cognitive performance were explored using a two-group path model. No differences in whole-brain structural organisation were found. Bundle-specific metrics showed reduced fiber density (p = 0.012, Hedges' g = 0.884) and fiber density cross-section (p = 0.007, Hedges' g = 0.945) in the motor segment of the corpus callosum in COV compared to healthy controls. Cognitive performance on the motor praxis and digit symbol substitution tests was worse in COV than healthy controls (p < 0.001, r = 0.688; p = 0.013, r = 422, respectively). Associations between the cognitive performance and bundle-specific FD measures differed significantly between groups. WMM and cognitive performance differences were observed between COV and healthy controls.

A comparison of RSV and influenza in vitro kinetic parameters reveals differences in infecting time.

Influenza and respiratory syncytial virus (RSV) cause acute infections of the respiratory tract. Since the viruses both cause illnesses with similar symptoms, researchers often try to apply knowledge gleaned from study of one virus to the other virus. This can be an effective and efficient strategy for understanding viral dynamics or developing treatment strategies, but only if we have a full understanding of the similarities and differences between the two viruses. This study used mathematical modeling to quantitatively compare the viral kinetics of in vitro RSV and influenza virus infections. Specifically, we determined the viral kinetics parameters for RSV A2 and three strains of influenza virus, A/WSN/33 (H1N1), A/Puerto Rico/8/1934 (H1N1), and pandemic H1N1 influenza virus. We found that RSV viral titer increases at a slower rate and reaches its peak value later than influenza virus. Our analysis indicated that the slower increase of RSV viral titer is caused by slower spreading of the virus from one cell to another. These results provide estimates of dynamical differences between influenza virus and RSV and help provide insight into the virus-host interactions that cause observed differences in the time courses of the two illnesses in patients.

Comparison of Several White Matter Tracts in Feline and Canine Brain by Using Magnetic Resonance Diffusion Tensor Imaging.

Recently, we published a first anatomical diffusion tensor imaging (DTI) atlas regarding white matter tracts in the canine brain. The purpose of this study was to show the significance of DTI in the revelation of the white matter fibres in the feline brain (i.e., to obtain an anatomical DTI atlas of images) and to descriptively compare these to previously obtained white matter fibre images of the canine brain. DTI MR Images of four cats euthanized for reasons other than neurological disorders were obtained with a 3 T system. Combined fractional anisotropic (FA) and directional maps were obtained within the hour after death. An experienced anatomist tracked white matter tracts of clinical relevance using the scanner software. After validation of these tracts, we compared relevant neurological connections between the cat and the dog. Comparison of cerebral structures between different species is easier when the three dimensional anatomy is visualized by using DTI. 3D rendered DTI images clearly show major differences in neurological architecture between cats and dogs for example, the more important space occupying role of the limbic system, and the less diffuse, less nodular, less pronounced and thinner fibre bundles in the feline brain compared to the canine brain (except for the cerebellum different parts connecting fibres passing through the brainstem which are pronouncedly developed). Anat Rec, 300:1270-1289, 2017. © 2017 Wiley Periodicals, Inc.

PK/PD Modelling of the QT Interval: a Step Towards Defining the Translational Relationship Between In Vitro, Awake Beagle Dogs, and Humans.

Inhibiting the human ether-a-go-go-related gene (hERG)-encoded potassium ion channel is positively correlated with QT-interval prolongation in vivo, which is considered a risk factor for the occurrence of Torsades de Pointes (TdP). A pharmacokinetic/pharmacodynamic model was developed for four compounds that reached the clinic, to relate drug-induced QT-interval change in awake dogs and humans and to derive a translational scaling factor a 1. Overall, dogs were more sensitive than humans to QT-interval change, an a 1 of 1.5 was found, and a 10% current inhibition in vitro produced a higher percent QT-interval change in dogs as compared to humans. The QT-interval changes in dogs were predictive for humans. In vitro and in vivo information could reliably describe the effects in humans. Robust translational knowledge is likely to reduce the need for expensive thorough QT studies; therefore, expanding this work to more compounds is recommended.

Predicting the outcome of phase III trials using phase II data: a case study of clinical trial simulation in late stage drug development.

Maximizing the likelihood of success in Phase III is the ultimate goal of the use of modelling and simulation in the drug development process. The success in Phase III depends primarily on two questions: 1) Is the drug regimen actually efficacious and safe in the targeted patient population?, and 2) Will the planned Phase III clinical trial(s) be successful in demonstrating this? Traditionally, the first question is addressed in a qualitative, overall interpretation of available study results. Integrating this information into a formal statistical model of the action of the drug, allows running simulations to investigate the impact of uncertainties and imprecision in this knowledge. The second question is related to having an adequately designed clinical trial. Clinical trial simulation, using a drug action model, supplemented with appropriate models for disease progression and trial execution, allows assessing the impact of typical design features such as doses, sample size, in-/exclusion criteria, drop-out and trial duration on the trial outcome and thus optimising trial design. In this contribution, the use of modelling and simulation in the Phase II to Phase III transition is illustrated using real data of a drug for symptom relief in a chronic condition. A dose-response model of the clinical response was developed using data from Phase II. Simulations were performed to 1) generate the range of possible outcomes of ongoing Phase III trials and compare these to the blinded data being generated from these trials; 2) assess the robustness of the ongoing Phase III trials with respect to uncertainty of the true dose-response, patient variability in baseline severity and drug-response, and 3) assess the likelihood of achieving a clinically relevant response with a dose lower than those included in the trials.

Meniscal tears: comparison of half-Fourier technique and conventional MR imaging.

PURPOSE: To determine whether half-Fourier MR image acquisition technique can provide similar information to that of conventional MR acquisition technique for evaluation of meniscal tears. MATERIALS AND METHODS: We studied 101 menisci in 52 patients who were referred for evaluation of meniscal tears. Sagittal MR images of the knee were obtained for all patients by using proton density and T2-weighted SE sequences on a 1-T clinical system. The half-Fourier technique and conventional technique were used for all patients. All other imaging parameters were identical for both sequences (TR/TE=2400/20,70; 3 mm slice thickness; 200 x 256 matrix; field of view, 200; one signal acquired). Both sets of images were filmed with standard window and level settings. Images were randomised and interpreted independently by two radiologists for the presence of meniscal tears. Images were also subjectively assessed for image quality using a five-point grading scale. RESULTS: On half-Fourier images, Reader 1 interpreted 23 menisci as torn, compared to 28 for Reader 2. On conventional images, Reader 1 interpreted 24 menisci as torn, compared to 26 for Reader 2. Agreement between interpretation of the conventional and that of the half-Fourier images was 99% for Reader 1, and 98% for Reader 2. Agreement between readers for the half-Fourier images was 95%, and for the conventional images 96%. No statistically significant difference was found in the subjective evaluation of image quality between the conventional and half-Fourier images. CONCLUSION: The half-Fourier acquisition technique compares favourably with the conventional technique for the evaluation of meniscal tears.

Sensitivity of individual items of the Positive and Negative Syndrome Scale (PANSS) and items subgroups to differentiate between placebo and drug treatment in schizophrenia.

Lack of hard clinical endpoints is an essential problem in schizophrenia research. Disease state and treatment outcomes are measured using rating scales, e.g. Positive and Negative Syndrome Scale (PANSS). However, the PANSS score cannot always differentiate between placebo and drug treatment, even for established antipsychotics. The goal of this study was to identify the individual items of PANSS and subscales of selected items which are most sensitive to differentiate between placebo and drug effect. We analysed data from seven clinical trials of different antipsychotics. "Mini-PANSS" scales consisting of the most sensitive items were created and analysed statistically. The power of these scales to show a significant difference between placebo and drug treatment was compared with the power of total PANSS. Furthermore, pharmacokinetic-pharmacodynamic analysis was performed to determine which of these scales shows the highest drug effect on top of the placebo effect. The results reveal that all 30 items of the PANSS scale show a therapeutic drug effect. The magnitude of placebo effect was not predictive for the power to detect drug effect. Mini-PANSS scales consisting of items with the largest drug treatment response and the scale with the largest mean-to-SD ratio are somewhat better in differentiating between placebo and drug treatment than the total PANSS. However, the difference between these scales and total PANSS is small. Therefore, our analysis does not support replacement of the total PANSS by a reduced scale in the analysis of primary endpoints.

Diffusion tensor imaging of white matter tracts in the dog brain.

Diffusion weighted imaging sequences are now widely available on Magnetic Resonance Imaging (MRI) scanners. Diffusion Tensor Imaging (DTI) of the brain is able to show white matter tracts and is now commonly used in human medicine to study brain anatomy, tumors, structural pathways,… The purpose of this study was to show the interest of DTI to reveal the white matter fibers in the dogs' brain. DTI MR Images for this study were obtained with a 3 T system of 4 dogs euthanized for other reasons than neurological disorders. Combined fractional anisotropic (FA) and directional maps were obtained in the first 2 hours after death. The heads were amputated immediately after scanning and stored in 10% formalin until preparation for dissection. An experienced anatomist tracked white matter tracts with clinical relevance using the scanner software. The selected tracts were REFVIDume rendered and correlated with gross dissection. Using DTI we were able to track relevant neurological connections, such as the corticospinal tract, the optic and the cerebellar tract. The three dimensional anatomy is better presented using modern visualization techniques. DTI seems to be a valuable tool in order to present clinically relevant white matter tracts to neurological clinicians and researchers.

A canine model to evaluate efficacy and safety of γ-secretase inhibitors and modulators.

Gamma-secretase, a membrane bound protease which cleaves the transmembrane protein amyloid-ß protein precursor (AßPP), is a therapeutic target for Alzheimer's disease. Gamma-secretase inhibitors (GSIs) and modulators (GSMs) are being investigated as potential disease-modifying agents. Preclinical in vivo models to monitor the activity on gamma-secretase are described in different species such as mouse, rat, and guinea pigs. All these models have their value in testing compounds with amyloid lowering properties, however, compound characteristics and pharmacokinetic properties, as well as other species characteristics such as limited sampling volumes of cerebrospinal fluid (CSF), recommended the use of a larger, non-rodent animal species. For this purpose, a screening model in dogs was developed for testing GSIs and GSMs. We showed that GSIs and GSMs had a dose- and time-dependent effect on Aß(37), Aß(38), Aß(40), and Aß(42) in CSF. Changes in liver function were evidenced by a transient increase in bilirubin with the GSMs and incidental increases in alanine aminotransferase for GSMs as well as GSIs. Microarray analysis of liver biopsies enabled to elucidate potential mechanisms behind the liver function changes. The relevance of the liver findings should be further evaluated in chronic pre-clinical safety studies and in humans. Based on our data, we can conclude that the dog is a very appropriate species to assess efficacy and safety of compounds which have an effect on AßPP processing such as GSMs, GSIs, and BACE-inhibitors.

Postmastectomy lymphoedema: different patterns of fluid distribution visualised by ultrasound imaging compared with magnetic resonance imaging.

OBJECTIVES: Postmastectomy lymphoedema remains a disabling complication caused by treatment for breast cancer. The increased thickness of the dermal layer and the increased volume of the subcutis represent the most important contributions to the total swelling of the arm. Ultrasound imaging of the subcutaneous layer results in different patterns of reflected ultrasound waves depending on the morphological alternations that occurred due to impaired lymphatic drainage. The aim of this study was to compare these echographic images with those obtained using magnetic resonance imaging to explain the nature of the morphological changes. DESIGN: Observational study. SETTING: Patients were recruited from the Breast Clinic at the University Hospital Brussels. PARTICIPANTS: Seven women (mean age 60 years) with unilateral breast cancer who subsequently developed lymphoedema. MAIN OUTCOME MEASURES: The water displacement technique was applied to determine arm volumes, and echographic and magnetic resonance images were used to evaluate changes in tissue structures. RESULTS: Volumetric measurements of the arm (mean affected arm 3241 ml vs unaffected arm 2538 ml) showed a significant increase in total arm volume of 703 ml (95% confidence interval 324 to 1084 ml). Using echography, the thickness of the dermal and subcutaneous layers showed an average increase of 0.2 to 0.8mm and 3.9 to 7.2mm, respectively. The differences between the affected arm and the unaffected arm for all upper and lower arm measurements (i.e. volumetry, dermal and subcutaneous thickness) were significant, but no significant differences were registered for hand measurements. On echography, the dermis showed uniform changes, with a homogenous hypo-echogenic appearance compared with the contralateral side due to water influx. Different patterns of structural changes could be visualised within the subcutis: (1) uniformly hypo-echogenic due to the diffuse spread of water through the subcutis; (2) hyperechogenic areas surrounded by hypo-echogenic streaks visualised on magnetic resonance imaging as adipose tissue surrounded by fluid embedded in fibrous tissue; and (3) homogenously hyperechogenic due to the overgrowth of adipose tissue with a minimal amount of water. CONCLUSIONS: Echographic images can help to determine the likelihood that complex physical therapy will reduce lymphoedema, and evaluate treatment results by measuring tissue thickness and evaluating tissue consistency.

Histological findings compared with magnetic resonance and ultrasonographic imaging in irreversible postmastectomy lymphedema: a case study.

Postmastectomy edema is a current complication after axillary lymph node dissection in cases of breast cancer treatment. Staging is important in order to select those patients who can benefit from complex physical therapy (CPT). Different imaging techniques can be used to evaluate the edema. Ultrasonography (US) is a harmless, cheap, and easily applicable technique to visualize the dermal and subcutaneous tissue, but interpretation of the obtained images is not always evident. The aim of this study was to compare ultrasound images of irreversible edema with tissue histology, magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). Ultrasonographic images of the edematous dermis show an homogeneous hypoechogenic dermal layer that appears on tissue histology to be less compact, due to the excess of fluid in the interstitium separating the collagen fibres and making it more transparent on light microscopy. MRI of the dermis gives a hyperintense signal, indicating the presence of fluid. In the subcutis, increase of the adipose tissue could be observed on US, MRI, and tissue histology. In the case of lymphedema, the area and perimeter of fat cells is significantly (p < 0.05) increased. Hypoechogenic areas near the muscle fascia are registered on US corresponding with epifascial fluid on MRI, and hyperechogenic branches are embedded within the adipose tissue, on tissue histology seen as large fibrotic septa enclosing adipose cells. MRI has a honeycomb picture corresponding with fluid bound to fibrosis.