Identification of an MCM4 homologue expressed specifically in the sexual stage of Plasmodium falciparum.

Mini-chromosome maintenance (MCM) proteins play an essential role in DNA replication initiation. We have isolated a novel gene encoding an MCM-like protein from the human malaria parasite Plasmodium falciparum using the vectorette technique. The gene has no introns and comprises an open reading frame encoding 1005 amino acid residues with a predicted Mr of 115 kDa. The encoded protein, termed PfMCM4, contains all conserved sequences in the MCM family and displays the highest homology to the Cdc54 (MCM4) of Saccharomyces cerevisiae. However, PfMCM4 possesses five unique amino acid inserts with sizes ranging from seven to 75 residues. Southern blotting of genomic DNA digests and chromosomal separations showed that the Pfmcm4 gene is present as a single copy per haploid genome and is located on chromosome 13. A 4000-nucleotide transcript of this gene is expressed specifically in the sexual erythrocytic stage, indicating that PfMCM4 may be involved in gametogenesis in which DNA is quickly replicated

Quantifying Numerical Errors in the Simulation of Transcranial Ultrasound using Pseudospectral Methods

Effective transcranial transmission of focused ultrasound is desirable for various therapeutic applications. Time-reversal (TR) focusing based on numerical simulations of ultrasound propagation can be used to correct for the aberrating skull layer. For weakly heterogeneous media, k-space and pseudospectral time domain (PSTD) methods have been shown to have increased accuracy and efficiency compared to the finite-difference time domain (FDTD) methods typically used in TR. However, their suitability for highly heterogeneous, transcranial simulations is less clear. Here, this is established in terms of spatial and temporal sampling requirements through numerical testing and comparison with FDTD schemes. PSTD schemes are shown to give equal or better accuracy compared to FDTD schemes for modelling propagation through tissue-realistic heterogeneities, which, combined with the reduction in numerical dispersion obtained with k-space correction, recommends them for use in simulated TR

Alemtuzumab use in neuromyelitis optica spectrum disorders: a brief case series.

Alemtuzumab is an anti-CD52 monoclonal antibody recently licensed for use in relapsing-remitting multiple sclerosis. Here, we report our experience of its use in neuromyelitis optica (NMO) spectrum disorders. A retrospective case review of patients treated with alemtuzumab in Cambridge, UK, was conducted to identify those who fulfil the criteria for NMO spectrum disorder. Three cases were identified. Case 1, 9-year-old female, presented with transverse myelitis and bilateral optic neuritis,with one lower medullary and several longitudinally extensive cord lesions. Despite immunosuppression including two courses of alemtuzumab, she continued to relapse, was wheelchair bound and registered blind by age 12, and died at age 18. Case 2, 41-year-old female, presented with bilateral optic neuritis and transverse myelitis with longitudinally extensive cervical cord lesions. Despite three courses of alemtuzumab, she had five relapses with visual impairment and new cord lesions. She later developed tumefactive white matter lesions and died aged 51.Case 3, 31-year-old female, presented with transverse myelitis with longitudinally extensive cervical cord lesions and positive aquaporin-4 antibody. After one course of alemtuzumab, she relapsed with 4 episodes of myelitis with new enhancing lesions and accumulating disability. She became relapse free after rituximab and mycophenolate mofetil. From this case series, we conclude that alemtuzumab failed to prevent disabling relapses and poor outcome in NMO. We hypothesise that rituximab is more effective, as in case 3, because it causes much more prolonged B lymphocyte depletion than alemtuzumab. We therefore caution against the use of alemtuzumab in NMO.Clinical work is performed at the Wellcome Clinical Research Facility. JLJ and AJC are supported by the Cambridge Biomedical Research Centre of the National Institute for Health Research

Time domain reconstruction of sound speed and attenuation in ultrasound computed tomography using full wave inversion

Ultrasound computed tomography (USCT) is a non-invasive imaging technique that provides information about the acoustic properties of soft tissues in the body, such as the speed of sound (SS) and acoustic attenuation (AA). Knowledge of these properties can improve the discrimination between benign and malignant masses, especially in breast cancer studies. Full wave inversion (FWI) methods for image reconstruction in USCT provide the best image quality compared to more approximate methods. Using FWI, the SS is usually recovered in the time domain, and the AA is usually recovered in the frequency domain. Nevertheless, as both properties can be obtained from the same data, it is desirable to have a common framework to reconstruct both distributions. In this work, an algorithm is proposed to reconstruct both the SS and AA distributions using a time domain FWI methodology based on the fractional Laplacian wave equation, an adjoint field formulation, and a gradient-descent method. The optimization code employs a Compute Unified Device Architecture version of the software k-Wave, which provides high computational efficiency. The performance of the method was evaluated using simulated noisy data from numerical breast phantoms. Errors were less than 0.5% in the recovered SS and 10% in the AA. V

Concomitant ablation of atrial fibrillation in octogenarians: an observational study

<p>Abstract</p> <p>Background</p> <p>Cardiac surgery is increasingly required in octogenarians. These patients frequently present atrial fibrillation (AF), a significant factor for stroke and premature death. During the last decade, AF ablation has become an effective procedure in cardiac surgery. Because the results of concomitant AF ablation in octogenarians undergoing cardiac surgery are still not clear, we evaluated the outcome in these patients.</p> <p>Methods</p> <p>Among 200 patients undergoing concomitant AF ablation (87% persistent AF), 28 patients were ≥ 80 years (82 ± 2.4 years). The outcome was analysed by prospective follow up after 3, 6, 12 months and annually thereafter. Freedom from AF was calculated according to the Kaplan-Meier method.</p> <p>Results</p> <p>Octogenarians were similar to controls regarding AF duration (48 ± 63.2 versus 63 ± 86.3 months, n.s.) and left atrial diameter (49 ± 6.1 versus 49 ± 8.8 mm, n.s.), but differed in EuroSCORE (17.3 ± 10.93 versus 7.4 ± 7.31%, p < 0.001), prevalence of paroxysmal AF (25.0 versus 11.0%, p = 0.042) and aortic valve disease (67.8 versus 28.5%, p < 0.001). ICU stay (8 ± 16.9 versus 4 ± 7.2 days, p = 0.027), hospital stay (20 ± 23.9 versus 14 ± 30.8 days, p < 0.05), and 30-d-mortality (14.3 versus 4.6%, p = 0.046) were increased. After 12 ± 6.1 months of follow-up (95% complete), 14 octogenarians (82%) and 101 controls (68%, n.s.) were in sinus rhythm; 59% without antiarrhythmic drugs in either group (n.s.). Sinus rhythm restoration was associated with improved NYHA functional class and renormalization of left atrial size. Cumulative freedom from AF demonstrated no difference between groups. Late mortality was higher in octogenarians (16.7 versus 6.1%, p = 0.065).</p> <p>Conclusion</p> <p>Sinus rhythm restoration rate and functional improvement are satisfactory in octogenarians undergoing concomitant AF ablation. Hence, despite an increased perioperative risk, this procedure should be considered even in advanced age.</p

The value of source data verification in a cancer clinical trial

Background Source data verification (SDV) is a resource intensive method of quality assurance frequently used in clinical trials. There is no empirical evidence to suggest that SDV would impact on comparative treatment effect results from a clinical trial. Methods Data discrepancies and comparative treatment effects obtained following 100% SDV were compared to those based on data without SDV. Overall survival (OS) and Progression-free survival (PFS) were compared using Kaplan-Meier curves, log-rank tests and Cox models. Tumour response classifications and comparative treatment Odds Ratios (ORs) for the outcome objective response rate, and number of Serious Adverse Events (SAEs) were compared. OS estimates based on SDV data were compared against estimates obtained from centrally monitored data. Findings Data discrepancies were identified between different monitoring procedures for the majority of variables examined, with some variation in discrepancy rates. There were no systematic patterns to discrepancies and their impact was negligible on OS, the primary outcome of the trial (HR (95% CI): 1.18(0.99 to 1.41), p = 0.064 with 100% SDV; 1.18(0.99 to 1.42), p = 0.068 without SDV; 1.18(0.99 to 1.40), p = 0.073 with central monitoring). Results were similar for PFS. More extreme discrepancies were found for the subjective outcome overall objective response (OR (95% CI): 1.67(1.04 to 2.68), p = 0.03 with 100% SDV; 2.45(1.49 to 4.04), p = 0.0003 without any SDV) which was mostly due to differing CT scans. Interpretation Quality assurance methods used in clinical trials should be informed by empirical evidence. In this empirical comparison, SDV was expensive and identified random errors that made little impact on results and clinical conclusions of the trial. Central monitoring using an external data source was a more efficient approach for the primary outcome of OS. For the subjective outcome objective response, an independent blinded review committee and tracking system to monitor missing scan data could be more efficient than SDV

Vitamin D Status and its Association with Morbidity including Wasting and Opportunistic Illnesses in HIV-Infected Women in Tanzania.

Vitamin D has a potential role in preventing HIV-related complications, based on its extensive involvement in immune and metabolic function, including preventing osteoporosis and premature cardiovascular disease. However, this association has not been examined in large studies or in resource-limited settings. Vitamin D levels were assessed in 884 HIV-infected pregnant women at enrollment in a trial of multivitamin supplementation (excluding vitamin D) in Tanzania. Information on HIV related complications was recorded during follow-up (median, 70 months). Proportional hazards models and generalized estimating equations were used to assess the relationship of vitamin D status with these outcomes. Women with low vitamin D status (serum 25-hydroxyvitamin D<32 ng/mL) had 43% higher risk of reaching a body mass index (BMI) less than 18 kg/m(2) during the first 2 years of follow-up, compared to women with adequate vitamin D levels (hazard ratio [HR]: 1.43; 95% confidence intervals: [1.03-1.99]). The relationship between continuous vitamin D levels and risk of BMI less than 18 kg/m(2) during follow-up was inverse and linear (p=0.03). Women with low vitamin D levels had significantly higher incidence of acute upper respiratory infections (HR: 1.27 [1.04-1.54]) and thrush (HR: 2.74 [1.29-5.83]) diagnosed during the first 2 years of follow-up. Low vitamin D status was a significant risk factor for wasting and HIV-related complications such as thrush during follow-up in this prospective cohort in Tanzania. If these protective associations are confirmed in randomized trials, vitamin D supplementation could represent a simple and inexpensive method to improve health and quality of life of HIV-infected patients, particularly in resource-limited settings

Sensitivity of simulated transcranial ultrasound fields to acoustic medium property maps

High intensity transcranial focused ultrasound is an FDA approved treatment for essential tremor, while low-intensity applications such as neurostimulation and opening the blood brain barrier are under active research. Simulations of transcranial ultrasound propagation are used both for focusing through the skull, and predicting intracranial fields. Maps of the skull acoustic properties are necessary for accurate simulations, and can be derived from medical images using a variety of methods. The skull maps range from segmented, homogeneous models, to fully heterogeneous models derived from medical image intensity. In the present work, the impact of uncertainties in the skull properties is examined using a model of transcranial propagation from a single element focused transducer. The impact of changes in bone layer geometry and the sound speed, density, and acoustic absorption values is quantified through a numerical sensitivity analysis. Sound speed is shown to be the most influential acoustic property, and must be defined with less than 4% error to obtain acceptable accuracy in simulated focus pressure, position, and volume. Changes in the skull thickness of as little as 0.1 mm can cause an error in peak intracranial pressure of greater than 5%, while smoothing with a 1 mm 3 kernel to imitate the effect of obtaining skull maps from low resolution images causes an increase of over 50% in peak pressure. The numerical results are confirmed experimentally through comparison with sonications made through 3D printed and resin cast skull bone phantoms

Omega-3 polyunsaturated fatty acids status and cognitive function in young women

© 2019 The Author(s). Background: Research indicates that low omega-3 polyunsaturated fatty acid (n-3 PUFA) may be associated with decreased cognitive function. This study examined the association between n-3 PUFA status and cognitive function in young Australian women. Methods: This was a secondary outcome analysis of a cross-sectional study that recruited 300 healthy women (18-35 y) of normal weight (NW: BMI 18.5-24.9 kg/m2) or obese weight (OB: BMI ≥30.0 kg/m2). Participants completed a computer-based cognition testing battery (IntegNeuro™) evaluating the domains of impulsivity, attention, information processing, memory and executive function. The Omega-3 Index (O3I) was used to determine n-3 PUFA status (percentage of EPA (20:5n-3) plus DHA (22:6n3) in the red cell membrane) and the participants were divided into O3I tertile groups: T1 6.75%. Potential confounding factors of BMI, inflammatory status (C-reactive Protein), physical activity (total MET-min/wk), alpha1-acid glycoprotein, serum ferritin and hemoglobin, were assessed. Data reported as z-scores (mean ± SD), analyses via ANOVA and ANCOVA. Results: Two hundred ninety-nine women (26.9 ± 5.4 y) completed the study (O3I data, n = 288). The ANOVA showed no overall group differences but a significant group × cognition domain interaction (p < 0.01). Post hoc tests showed that participants in the low O3I tertile group scored significantly lower on attention than the middle group (p = 0.01; ES = 0.45 [0.15-0.74]), while the difference with the high group was borderline significant (p = 0.052; ES = 0.38 [0.09-0.68]). After confounder adjustments, the low group had lower attention scores than both the middle (p = 0.01) and high (p = 0.048) groups. These findings were supported by univariate analyses which found significant group differences for the attention domain only (p = 0.004). Conclusions: Cognitive function in the attention domain was lower in women with lower O3I, but still within normal range. This reduced but normal level of cognition potentially provides a lower baseline from which cognition would decline with age. Further investigation of individuals with low n-3 PUFA status is warranted

Alterations in endo-lysosomal function induce similar hepatic lipid profiles in rodent models of drug-induced phospholipidosis and Sandhoff disease

Drug-induced phospholipidosis (DIPL) is characterized by an increase in the phospholipid content of the cell and the accumulation of drugs and lipids inside the lysosomes of affected tissues, including in the liver. Although of uncertain pathological significance for patients, the condition remains a major impediment for the clinical development of new drugs. Human Sandhoff disease (SD) is caused by inherited defects of the β subunit of lysosomal β-hexosaminidases (Hex) A and B, leading to a large array of symptoms, including neurodegeneration and ultimately death by the age of 4 in its most common form. The substrates of Hex A and B, gangliosides GM2 and GA2, accumulate inside the lysosomes of the CNS and in peripheral organs. Given that both DIPL and SD are associated with lysosomes and lipid metabolism in general, we measured the hepatic lipid profiles in rodent models of these two conditions using untargeted LC/MS to examine potential commonalities. Both model systems shared a number of perturbed lipid pathways, notably those involving metabolism of cholesteryl esters, lysophosphatidylcholines, bis(monoacylglycero)phosphates, and ceramides. We report here profound alterations in lipid metabolism in the SD liver. In addition, DIPL induced a wide range of lipid changes not previously observed in the liver, highlighting similarities with those detected in the model of SD and raising concerns that these lipid changes may be associated with underlying pathology associated with lysosomal storage disorders.This work was funded by a Medical Research Council Integrative Toxicology Training Partnership grant with financial support from GlaxoSmithKline. The work on Sandhoff mice was supported by SPARKS, The Children’s Medical Research Charity. JLG’s laboratory is supported by the Wellcome Trust (Equipment grant 093,148/Z/10/Z)) and the Medical Research Council (G0801841 & UD99999906)