Fourier transform infrared (FTIR) spectroscopy is a powerful yet relatively inexpensive and convenient technique for studying the structure and organization of membrane lipids in their various ...polymorphic phases. This spectroscopic technique yields information about the conformation and dynamics of all regions of the lipid molecule simultaneously without the necessity of introducing extrinsic probes. In this review, we summarize some relatively recent FTIR spectroscopic studies of the structure and organization primarily of fully hydrated phospholipids in their biologically relevant lamellar crystalline, gel and liquid–crystalline phases, and show that interconversions between these bilayer phases can be accurately monitored by this technique. We also briefly discuss how the structure and organization of potentially biologically relevant nonlamellar micellar or reversed hexagonal lipid phases can be studied and how phase transitions between lamellar and nonlamellar phases, or between various nonlamellar phases, can be followed as well. In addition, we discuss the potential for FTIR spectroscopy to yield fairly high resolution structural information about phospholipid packing in lamellar crystalline or gel phases. Finally, we show that many, but not all of these FTIR approaches can also yield valuable information about lipid–protein interactions in membrane protein- or peptide-containing lipid membrane bilayer model or even in biological membranes. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.
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► We review the application of Fourier transform infrared (FTIR) spectroscopy to lipids. ► This powerful non-perturbing technique can be used to study lipid phase transitions. ► FTIR spectroscopy provides valuable information about the structure of lipid phases. ► FTIR spectroscopy gives key information about lipid/protein interactions in membranes.
The do-it-yourself artificial pancreas system (DIYAPS) is a patient-driven initiative with the potential to revolutionise diabetes management, automating insulin delivery with existing pumps and CGM ...combined with open-source algorithms. Given the considerable interest in this topic within the diabetes community, we have conducted a systematic review of DIYAPS efficacy, safety, and user experience. Following recognised procedures and reporting standards, we identified 10 eligible publications of 730 participants within the peer-reviewed literature. Overall, studies reported improvements in time in range, HbA1c (glycated haemoglobin), reduced hypoglycaemia, and improved quality of life with DIYAPS use. While results were positive, the identified studies were small, and the majority were observational and at high risk of bias. Further research including well-designed randomised trials comparing DIYAPS with appropriate comparators is recommended.
The pathogenicity of the opportunistic human fungal pathogen Candida albicans depends on its ability to escape destruction by the host immune system. Using mutant strains that are defective in cell ...surface glycosylation, cell wall protein synthesis, and yeast-hypha morphogenesis, we have investigated three important aspects of C. albicans innate immune interactions: phagocytosis by primary macrophages and macrophage cell lines, hyphal formation within macrophage phagosomes, and the ability to escape from and kill macrophages. We show that cell wall glycosylation is critically important for the recognition and ingestion of C. albicans by macrophages. Phagocytosis was significantly reduced for mutants deficient in phosphomannan biosynthesis (mmn4Δ, pmr1Δ, and mnt3 mnt5Δ), whereas O- and N-linked mannan defects (mnt1Δ mnt2Δ and mns1Δ) were associated with increased ingestion, compared to the parent wild-type strains and genetically complemented controls. In contrast, macrophage uptake of mutants deficient in cell wall proteins such as adhesins (ece1Δ, hwp1Δ, and als3Δ) and yeast-locked mutants (clb2Δ, hgc1Δ, cph1Δ, efg1Δ, and efg1Δ cph1Δ), was similar to that observed for wild-type C. albicans. Killing of macrophages was abrogated in hypha-deficient strains, significantly reduced in all glycosylation mutants, and comparable to wild type in cell wall protein mutants. The diminished ability of glycosylation mutants to kill macrophages was not a consequence of impaired hyphal formation within macrophage phagosomes. Therefore, cell wall composition and the ability to undergo yeast-hypha morphogenesis are critical determinants of the macrophage's ability to ingest and process C. albicans.
Skeletal muscle (SkM) regenerates following injury, replacing damaged tissue with high fidelity. However, in serious injuries, non-regenerative defects leave patients with loss of function, increased ...re-injury risk and often chronic pain. Progress in treating these non-regenerative defects has been slow, with advances only occurring where a comprehensive understanding of regeneration has been gained. Tissue engineering has allowed the development of bioengineered models of SkM which regenerate following injury to support research in regenerative physiology. To date, however, no studies have utilised human myogenic precursor cells (hMPCs) to closely mimic functional human regenerative physiology.
Here we address some of the difficulties associated with cell number and hMPC mitogenicity using magnetic association cell sorting (MACS), for the marker CD56, and media supplementation with fibroblast growth factor 2 (FGF-2) and B-27 supplement. Cell sorting allowed extended expansion of myogenic cells and supplementation was shown to improve myogenesis within engineered tissues and force generation at maturity. In addition, these engineered human SkM regenerated following barium chloride (BaCl
) injury. Following injury, reductions in function (87.5%) and myotube number (33.3%) were observed, followed by a proliferative phase with increased MyoD+ cells and a subsequent recovery of function and myotube number. An expansion of the Pax7+ cell population was observed across recovery suggesting an ability to generate Pax7+ cells within the tissue, similar to the self-renewal of satellite cells seen in vivo.
This work outlines an engineered human SkM capable of functional regeneration following injury, built upon an open source system adding to the pre-clinical testing toolbox to improve the understanding of basic regenerative physiology.
In this review article, we summarize the current state of biophysical knowledge concerning the phase behavior and organization of cardiolipin (CL) and CL-containing phospholipid bilayer model ...membranes. We first briefly consider the occurrence and distribution of CL in biological membranes and its probable biological functions therein. We next consider the unique chemical structure of the CL molecule and how this structure may determine its distinctive physical properties. We then consider in some detail the thermotropic phase behavior and organization of CL and CL-containing lipid model membranes as revealed by a variety of biophysical techniques. We also attempt to relate the chemical properties of CL to its function in the biological membranes in which it occurs. Finally, we point out the requirement for additional biophysical studies of both lipid model and biological membranes in order to increase our currently limited understanding of the relationship between CL structure and physical properties and CL function in biological membranes.
We present a detailed kinematic analysis of the outer halo globular cluster system of the Andromeda galaxy (M31). Our basis for this is a set of new spectroscopic observations for 78 clusters lying ...at projected distances between R
proj ∼ 20–140 kpc from the M31 centre. These are largely drawn from the recent Pan-Andromeda Archaeological Survey globular cluster catalogue; 63 of our targets have no previous velocity data. Via a Bayesian maximum likelihood analysis, we find that globular clusters with R
proj > 30 kpc exhibit coherent rotation around the minor optical axis of M31, in the same direction as more centrally located globular clusters, but with a smaller amplitude of 86 ± 17 km s−1. There is also evidence that the velocity dispersion of the outer halo globular cluster system decreases as a function of projected distance from the M31 centre, and that this relation can be well described by a power law of index ≈ −0.5. The velocity dispersion profile of the outer halo globular clusters is quite similar to that of the halo stars, at least out to the radius up to which there is available information on the stellar kinematics. We detect and discuss various velocity correlations amongst subgroups of globular clusters that lie on stellar debris streams in the M31 halo. Many of these subgroups are dynamically cold, exhibiting internal velocity dispersions consistent with zero. Simple Monte Carlo experiments imply that such configurations are unlikely to form by chance, adding weight to the notion that a significant fraction of the outer halo globular clusters in M31 have been accreted alongside their parent dwarf galaxies. We also estimate the M31 mass within 200 kpc via the Tracer Mass Estimator (TME), finding (1.2–1.6) ± 0.2 × 1012 M⊙. This quantity is subject to additional systematic effects due to various limitations of the data, and assumptions built in into the TME. Finally, we discuss our results in the context of formation scenarios for the M31 halo.
Summary Objective Quadriceps weakness has been reported with incident but not progressive knee osteoarthritis (OA) in longitudinal studies. This study examined the relationship between quadriceps ...strength and worsening of knee joint space narrowing (JSN) over 30 months. Methods Longitudinal, observational study of adults aged 50–79 years with OARSI JSN score <3 at baseline. Baseline measures included bilateral weight-bearing fixed flexion radiographs, isokinetic concentric quadriceps and hamstring strength, height and weight, and physical activity. Hamstring:quadriceps (H:Q) strength ratios also were evaluated. Worsening was defined as an increase in JSN score in the tibiofemoral and/or patellofemoral compartments on 30-month radiographs or total knee replacement. Knee-based analyses used generalized estimating equations, stratified by sex, to assess relationships between strength and knee JSN while controlling for covariance between knees within subjects as well as age, body mass index (BMI), history of knee injury and/or surgery, physical activity level and alignment. Results 3856 knees (2254 females and 1602 males) with JSN score <3 at baseline and no missing follow-up data were included. Mean ± SD age was 62.2 ± 7.7 in women and 61.6 ± 8.1 in men. Women in the lowest tertile of quadriceps strength had an increased risk of whole knee JSN (OR = 1.66, 95% CI = 1.26, 2.19) and tibiofemoral JSN (OR = 1.69, 95% CI = 1.26, 2.28). However, no associations were found between strength and JSN in men or H:Q < 0.6 and JSN in men or women. Conclusions In women but not in men, quadriceps weakness was associated with increased risk for tibiofemoral and whole knee JSN.
We present a renewed look at M31's giant stellar stream along with the nearby structures streams C and D, exploiting a new algorithm capable of fitting to the red giant branch (RGB) of a structure in ...both colour and magnitude space. Using this algorithm, we are able to generate probability distributions in distance, metallicity and RGB width for a series of subfields spanning these structures. Specifically, we confirm a distance gradient of approximately 20 kpc per degree along a 6 deg extension of the giant stellar stream, with the farthest subfields from M31 lying ∼120 kpc more distant than the innermost subfields. Further, we find a metallicity that steadily increases from
$-0.7^{+0.1}_{-0.1}$
to
$-0.2^{+0.2}_{-0.1}$
dex along the inner half of the stream before steadily dropping to a value of
$-1.0^{+0.2}_{-0.2}$
dex at the farthest reaches of our coverage. The RGB width is found to increase rapidly from
$0.4^{+0.1}_{-0.1}$
to
$1.1^{+0.2}_{-0.1}$
dex in the inner portion of the stream before plateauing and decreasing marginally in the outer subfields of the stream. In addition, we estimate stream C to lie at a distance between 794 and 862 kpc and stream D between 758 and 868 kpc. We estimate the median metallicity of stream C to lie in the range −0.7 to −1.6 dex and a metallicity of
$-1.1^{+0.3}_{-0.2}$
dex for stream D. RGB widths for the two structures are estimated to lie in the range 0.4–1.2 dex and 0.3–0.7 dex, respectively. In total, measurements are obtained for 19 subfields along the giant stellar stream, four along stream C, five along stream D and three general M31 spheroid fields for comparison. We thus provide a higher resolution coverage of the structures in these parameters than has previously been available in the literature.
We undertake an investigation into the spatial structure of the M31 satellite system utilizing the distance distributions presented in a previous publication. These distances make use of the unique ...combination of depth and spatial coverage of the Pan-Andromeda Archaeological Survey to provide a large, homogeneous sample consisting of 27 of M31's satellites, as well as M31 itself. We find that the satellite distribution, when viewed as a whole, is no more planar than one would expect from a random distribution of equal size. A disk consisting of 15 of the satellites is however found to be highly significant, and strikingly thin, with an rms thickness of just (ProQuest: Formulae and/or non-USASCII text omitted) kpc. This disk is oriented approximately edge-on with respect to the Milky Way and almost perpendicular to the Milky Way disk. It is also roughly orthogonal to the disk-like structure regularly reported for the Milky Way satellite system and in close alignment with M31's Giant Stellar Stream. A similar analysis of the asymmetry of the M31 satellite distribution finds that it is also significantly larger than one would expect from a random distribution. In particular, it is remarkable that 20 of the 27 satellites most likely lie on the Milky Way side of the galaxy, with the asymmetry being most pronounced within the satellite subset forming the aforementioned disk. This lopsidedness is all the more intriguing in light of the apparent orthogonality observed between the satellite disk structures of the Milky Way and M31.
The increasing prevalence of insecticide resistance and the ongoing global burden of vector-borne diseases have encouraged new efforts in mosquito control. For Aedes aegypti, the most important ...arboviral vector, integration rates achieved in Cas9-based knock-ins so far have been rather low, highlighting the need to understand gene conversion patterns and other factors that influence homology-directed repair (HDR) events in this species. In this study, we report the effects of sequence mismatches or donor template forms on integration rates. We found that modest sequence differences between construct homology arms DNA sequence in the donor template which resembles the region flanking the target cut and genomic target comprising 1.2% nucleotide dissimilarity (heterology) significantly reduced integration rates. While most integrations (59-88%) from plasmid templates were the result of canonical on target, perfect repair HDR events, no canonical events were identified from other donor types (i.e. ssDNA, biotinylated ds/ssDNA). Sequencing of the transgene flanking region in 69 individuals with canonical integrations revealed 60% of conversion tracts to be unidirectional and extend up to 220 bp proximal to the break, though in three individuals bidirectional conversion of up to 725 bp was observed.
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