The contributions of extracellular matrix and sarcomere properties to passive muscle stiffness in cerebral palsy

Cerebral palsy results from an upper motor neuron lesion and has significant effects on skeletal muscle stiffness throughout the body. The increased stiffness that occurs is partly a result of changes in the microstructural components of muscle. In particular, alterations in extracellular matrix, sarcomere length, fibre diameter, and fat content have been reported; however, experimental studies have shown wide variability in the degree to which each component is altered. Many studies have reported alterations in the extracellular matrix, while others have reported no changes. A consistent finding throughout the literature is increased sarcomere length in cerebral palsy muscle. Often more than one component is altered, making it difficult to determine the individual effects on stiffness. The purpose of this study is to use a modeling approach to isolate individual effects of microstructural alterations that typically occur during cerebral palsy on whole muscle behavior; in particular, the extracellular matrix volume fraction, stiffness, and sarcomere length. These microstructural effects can be captured using a three dimensional model of muscle. We found that the extracellular matrix volume fraction has a larger effect on stiffness compared to sarcomere length, even when coupled with decreased extracellular matrix stiffness. Additionally, the effects of sarcomere length in passive stiffness are mitigated by the increased extracellular matrix volume fraction. Using this model, we can achieve a better understanding of the possible combinations of microstructural changes that can occur during cerebral palsy. Developing these insights into diseased muscle tissue will help to direct future clinical and experimental procedures.

Serat Pelepah Sagu Sebagai Alternatif Pengganti Serat Sintesis Fiberglass

Tujuan penelitian ini untuk menganalisis pengaruh ukuran besar diameter serat pelepah sagu terhadap sifat mekanik kekuatan tarik, menganalisis sifat mekanik tarik material komposit yang diperkuat serat pelepah sagu.Berdasarkan hasil penelitian; (1). Larutan NAoH berpengaruh terhadap kuat Tarik specimen, hal ini ditunjukkan pada 2,5% (NAoH terhadap H2O). Nilai kekuatan tariknya 49,486 N/mm2. (2). Serat pelepah sagu kuat tariknya jauh dibawah serat gelas. (48,435 N/mm2< 323 N/mm2). Hal ini disebabkan rongga yang terdapat di serat sintesis lebih rapat dibanding serat alami. (3). Berdasarkan variabel yang diteliti, kekuatan tarik (Ftu) dengan nilai tertinggi terjadi pada komposit (volume 85% matriks : 15% serat) yaitu sebesar 3,12 beban 11824 N. (4). Kekuatan tarik mengalami kenaikan terhadap peningkatan komposisi volume serat. (5). Spesimen uji yang mengalami regangan dan patah pada titik load yaitu pada komposisi volume 85% matriks : 15% serat sebesar 3,12 MPa dengan regangan sebesar 8% dan modulus young yang terjadi sebesar 38,615 MPa.The purpose of this study was to analyze the effect of the size of the sago frond fiber diameter on the mechanical properties of the tensile strength, to analyze the tensile mechanical properties of the composite material reinforced by sago frond fibers. Based on research results; (1) NaOH solution affects the tensile strength of the specimen. This is shown at 2.5% (NaOH to H2O), the tensile strength value is 49.486 N/mm2. (2) Sago frond fiber has a tensile strength far below the glass fiber (48,435 N/mm2 <323 N/mm2). This is because the cavities in synthetic fibers are denser than natural fibers. (3) Based on the variables studied, the tensile strength (Ftu) with the highest value occurs in the composite (85% matrix volume: 15% fiber), which is 3.12 load 11824 N. (4) Tensile strength increases with the increase in fiber volume composition. (5) The test specimens that experienced a strain and fracture at the load point, namely the composition of volume 85% matrix: 15% fiber was 3.12 MPa with a strain of 8% and the modulus young that occurred was 38.615 MPa.

Evaluation of Renal Fibrosis by Mapping Histology and Magnetic Resonance Imaging

<b><i>Background:</i></b> Renal fibrosis is a key driver of progression in chronic kidney disease (CKD). Recent advances in diagnostic imaging techniques have shown promising results for the noninvasive assessment of renal fibrosis. However, the specificity and accuracy of these techniques are controversial because they indirectly assess renal fibrosis. This limits fibrosis assessment by imaging in CKD for clinical practice. To validate magnetic resonance imaging (MRI) assessment for fibrosis, we derived representative models by mapping histology-proven renal fibrosis and imaging in CKD. <b><i>Methods:</i></b> Ninety-seven adult Chinese CKD participants with histology were studied. The kidney cortex interstitial extracellular matrix volume was calculated by the Aperio ScanScope system using Masson’s trichrome slices. The kidney cortex microcirculation was quantitatively assessed by peritubular capillary density using CD34 staining. The imaging techniques included intravoxel incoherent motion diffusion-weighted imaging and magnetic resonance elastography (MRE) imaging. Relevant analyses were performed to evaluate the correlations between MRI parameters and histology variables. Multiple linear regression models were used to describe the relationships between a response variable and other variables. The best-fit lines, which minimize the sum of squared residuals of the multiple linear regression models, were generated. <b><i>Results:</i></b> MRE values were negatively associated with the interstitial extracellular matrix volume (<i>Rho</i> = −0.397, <i>p</i> &#x3c; 0.001). The best mapping model of extracellular matrix volume with the MRE value and estimated glomerular filtration rate (eGFR) we obtained was as follows: Interstitial extracellular matrix volume = 218.504 – 14.651 × In(MRE) – 18.499 × In(eGFR). DWI-fraction values were positively associated with peritubular capillary density (<i>Rho</i> = 0.472, <i>p</i> &#x3c; 0.001). The best mapping model of peritubular capillary density with DWI-fraction value and eGFR was as follows: Peritubular capillaries density = 17.914 + 9.403 × (DWI – fraction) + 0.112 × (eGFR). <b><i>Conclusions:</i></b> The study provides histological evidence to support that MRI can effectively evaluate fibrosis in the kidney. These findings picture the graphs of the mapping model from imaging and eGFR into fibrosis, which has significant value for clinical implementation.

Real-time cardiovascular magnetic resonance tissue characterisation in patients undergoing transcatheter aortic valve replacement

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Research Foundation (DFG, CRC 1002, D1) Background Myocardial fibrosis is a major determinant of outcome in aortic stenosis (AS). Novel fast real-time (RT) cardiac magnetic resonance (CMR) mapping techniques allow comprehensive quantification of fibrosis but have not yet been compared against standard techniques and histology. Methods Patients with severe AS underwent CMR before (n = 110) and left ventricular (LV) endomyocardial biopsy (n = 46) at transcatheter aortic valve replacement (TAVR). Midventricular short axis (SAX) native, post-contrast T1 and extracellular volume fraction (ECV) maps were generated using commercially available MOLLI (native: 5(3)3, post-contrast: 4(1)3(1)2) and RT single-shot inversion recovery fast low-angle shot (FLASH) with radial undersampling. Focal late gadolinium enhancement was excluded from T1 and ECV regions of interest. ECV and LV mass were used to calculate LV matrix volumes. Variability and agreements were assessed between RT, MOLLI and histology using intraclass correlation coefficients, coefficients of variation and Bland Altman analyses. Results RT and MOLLI derived ECV were similar for midventricular SAX slice coverage (26.2 vs. 26.5, p = 0.073) and septal region of interest (26.2 vs. 26.5, p = 0.216). MOLLI native T1 time was in median 20 ms longer compared to RT (p &lt; 0.001). Agreement between RT and MOLLI was best for ECV (ICC &gt;0.91), excellent for post-contrast T1 times (ICC &gt;0.81) and good for native T1 times (ICC &gt;0.62). Diffuse collagen volume fraction by biopsies was in median 7.8%. ECV (RT r = 0.345, p = 0.039; MOLLI r = 0.40, p = 0.010) and LV matrix volumes (RT r = 0.45, p = 0.005; MOLLI r = 0.43, p = 0.007) were the only parameters associated with histology. Conclusions RT mapping offers fast and sufficient ECV and LV matrix volume calculation in AS. ECV and LV matrix volume represent robust and universally comparable parameters with associations to histologically assessed fibrosis and may emerge as potential targets for clinical decision making.

Structure formation peculiarities of nickel-filled polyvinylpyrrolidone copolymers during polymerization with simultaneous Ni2+ reduction

The course of the grafted polymerization of 2-hydroxyethylmethacrylate on polyvinylpyrrolidone with the formation of a reticulated copolymer with simultaneously chemical reduction of nickel ions is confirmed. The influence of the reduction process on the structural parameters of the polymeric matrix – the grafting efficiency and the content of polyvinylpyrrolidone in the copolymer, the molecular weight between crosslinks is established. The influence of the presence of polymer-monomer composition components on the particles formation of nickel filler is investigated. It has been found that the nickel ions reduction during the polymerization process promotes a uniform distribution of the formed metal particles in the polymer matrix volume.

Structural and functional reverse myocardial remodeling following transcatheter aortic valve replacement

Background Myocardial reverse remodeling determines outcome in patients with severe aortic stenosis (AS) following transcatheter aortic valve replacement (TAVR). However, little is known about the interplay of myocardial function and structure after TAVR. Since cardiac magnetic resonance (CMR) imaging allows comprehensive quantification of both structure and function we aimed to assess changes in myocardial tissue composition and deformation before and following TAVR. Methods CMR imaging was performed in 40 prospectively enrolled patients with severe AS before and one year after TAVR. Myocardial function was characterized using volumetry and CMR-feature-tracking (FT) deformation imaging of left ventricular (LV) global longitudinal strain (GLS) and atrial function (atrial reservoir ES, conduit Ee and booster pump strain EA). Myocardial structure was assessed using T1 mapping and late gadolinium enhancement (LGE) analysis. LV cellular and matrix volumes were calculated based on extra cellular volume fraction (ECV) and LV mass. CMR-FT results were compared to a control group of twenty patients with normal biventricular function. Moreover, biomarkers (NT-proBNP), functional (six-minute-walking-test) and clinical status (NYHA, Minnesota LIVING WITH HEART FAILURE score) were determined at baseline and one-year follow-up. Results Regression of both cellular (−20.6%, p&lt;0.001) and matrix volumes (−12.3%, p=0.003) and subsequently increased ECV (+9.0%, p=0.001) were documented one year after TAVR. Ventricular and atrial strains were impaired at baseline (GLS p=0.004, Es p&lt;0.001, Ee p&lt;0.001) and recovered during follow-up (GLS p&lt;0.001, Es p=0.005, Ee p=0.001). These changes were paralleled by improvements in NYHA (p&lt;0.001) and Minnesota (p&lt;0.001) scores as well as decline in NT-proBNP levels (p=0.001). There was a significant association of LV fibrosis as defined by matrix volume and extent of LGE and ventricular and atrial functional impairment (correlation of matrix volume and: GLS r=0.57, p&lt;0.001, Es r=−0.44, p=0.009; correlation of LGE%LV and: GLS r=0.41, p=0.015, Es: r=−0.4, p=0.02, and Ea: r=−0.41, p=0.02). Conclusion Regression of fibrosis and cellular hypertrophy determine improved myocardial function and recovery from heart failure following TAVR. Prognostic implications of the observed changes will need to be explored next to identify makers and therapeutic targets for optimized management of these patients. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): German Research Foundation (DFG, CRC 1002, D1)

Real-time cardiovascular magnetic resonance T1 and extracellular volume fraction mapping for tissue characterisation in aortic stenosis

Background Myocardial fibrosis is a major determinant of outcome in aortic stenosis (AS). Novel fast real-time (RT) cardiovascular magnetic resonance (CMR) mapping techniques allow comprehensive quantification of fibrosis but have not yet been compared against standard techniques and histology. Methods Patients with severe AS underwent CMR before (n = 110) and left ventricular (LV) endomyocardial biopsy (n = 46) at transcatheter aortic valve replacement (TAVR). Midventricular short axis (SAX) native, post-contrast T1 and extracellular volume fraction (ECV) maps were generated using commercially available modified Look-Locker Inversion recovery (MOLLI) (native: 5(3)3, post-contrast: 4(1)3(1)2) and RT single-shot inversion recovery Fast Low-Angle Shot (FLASH) with radial undersampling. Focal late gadolinium enhancement was excluded from T1 and ECV regions of interest. ECV and LV mass were used to calculate LV matrix volumes. Variability and agreements were assessed between RT, MOLLI and histology using intraclass correlation coefficients, coefficients of variation and Bland Altman analyses. Results RT and MOLLI derived ECV were similar for midventricular SAX slice coverage (26.2 vs. 26.5, p = 0.073) and septal region of interest (26.2 vs. 26.5, p = 0.216). MOLLI native T1 time was in median 20 ms longer compared to RT (p < 0.001). Agreement between RT and MOLLI was best for ECV (ICC > 0.91), excellent for post-contrast T1 times (ICC > 0.81) and good for native T1 times (ICC > 0.62). Diffuse collagen volume fraction by biopsies was in median 7.8%. ECV (RT r = 0.345, p = 0.039; MOLLI r = 0.40, p = 0.010) and LV matrix volumes (RT r = 0.45, p = 0.005; MOLLI r = 0.43, p = 0.007) were the only parameters associated with histology. Conclusions RT mapping offers fast and sufficient ECV and LV matrix volume calculation in AS patients. ECV and LV matrix volume represent robust and universally comparable parameters with associations to histologically assessed fibrosis and may emerge as potential targets for clinical decision making.

ANALISIS SIFAT MEKANIK KOMPOSIT LAMINA BERPENGUAT SERAT KACA WOVEN DENGAN MATRIKS UNSATURATED POLYESTER 2504 APT

Polymer composites has anisotropic properties, if it receives stress from outside it will increase deformation in all directions. This study aims to determine the effect of composites lamina made from woven glass fibers on 2504 APT unsaturated polyester on tensile and flexural strength. The research methodology used is as follows: the process of making composites using the Hand-Lay Up method, the matrix volume fraction Vfm = 69, 39%, the fiber volume fraction Vfs = 30, 38%. The research parameters observed are the x-direction stress (sx) and the y-axis direction strees, (sy). The results obtained are the y-axis, (sy) = 0.8% greater than the x-axis. The flexural strength of the x-axis direction, (sbx) = 57,7% greater than the y-axis direction. The difference in the value of the tensile strength occurs in the number of different fiber bonds, while the flexural strength of the y direction occurs in the fiber lamina which increases more.

Hyperglycemia compromises Rat Cortical Bone by Increasing Osteocyte Lacunar Density and Decreasing Vascular Canal Volume

Uncontrolled diabetes is associated with increased risk of bony fractures. However, the mechanisms have yet to be understood. Using high-resolution synchrotron micro-CT, we calculated the changes in the microstructure of femoral cortices of streptozotocin-induced hyperglycemic (STZ) Wistar Albino rats and tested the mechanical properties of the mineralized matrix by nanoindentation. Total lacunar volume of femoral cortices increased in STZ group due to a 9% increase in lacunar density. However, total vascular canal volume decreased in STZ group due to a remarkable decrease in vascular canal diameter (7 ± 0.3 vs. 8.5 ± 0.4 µm). Osteocytic territorial matrix volume was less in the STZ group (14,908 ± 689 µm3) compared with healthy controls (16,367 ± 391 µm3). In conclusion, hyperglycemia increased cellularity and lacunar density, decreased osteocyte territorial matrix, and reduced vascular girth, in addition to decreasing matrix mechanical properties in the STZ group when compared with euglycemic controls.