Fiber Shortening Research Articles

Melt processing of chemically modified cellulosic fibres with only water as plasticiser: Effects of moisture content and processing temperature

To replace petroleum-derived polymers with cellulose fibres, it is desirable to have the option of melt processing. However, upon heating, cellulose degradation typically starts before the material reaches its softening temperature. Alternatives to plastics should also, ideally, be recyclable via existing recycling streams. Here, we address the problem of melt processing cellulose as fibres while preserving recyclability. Native cellulose fibres were partially modified to dialcohol cellulose to impart thermoplastic characteristics. We demonstrate melt processing of these modified fibres with only water as plasticiser. Processability was investigated at selected processing temperatures and initial moisture content by monitoring the axial force of the extruder screws as a rheological indicator. The effects on molecular structure, fibre morphology and material properties were characterised by NMR spectroscopy, microscopy, tensile testing, fibre morphology analysis and X-ray diffraction. When comparing the melt-processed extrudate with handsheets, the already exceptional ductility was further increased. Moderate losses in tensile strength and stiffness were observed and are attributable loss of crystallinity and fibre shortening. This is the first report of strong and durable extrudates using cellulosic fibres as the only feedstock. Finally, the potential for recycling the processed material with unmodified fibres by paper recycling procedures was demonstrated.

Geometric changes of TMP fibres due to thermo-hydrolytic disintegration of waste MDF evaluated by three fibre analysers

ABSTRACT Thermo-hydrolytic disintegration of medium-density fibreboard (MDF) is a promising method for recovering fibres. This process, however, may affect the geometry and size distribution of the applied fibres initially obtained by thermomechanical pulping (TMP), and thus, the properties of MDF produced thereof. Optical methods based on image acquisition are increasingly common for geometrical characterisation to assess fibre quality. In this study, we analysed the size distribution of recovered fibres (RF) obtained by thermo-hydrolytic disintegration of urea–formaldehyde-bonded waste MDF and subsequent hammer-milling by using three optical fibre analysers, FibreShape Pro, QICPIC and Valmet FS5, while comparing them to virgin fibres (VF). The analysers use different evaluation methods and therefore gave different absolute values. Thus, size distributions could not be directly compared. Nevertheless, the results provided an indication of the changes that occurred during the manufacturing and recycling process. The RF displayed a similar fibre geometry to the VF, in spite of process-related shortening. Mean fibre length and length-based distribution of the VF were always greater than those of the RF, while fibre width of the hammer-milled RF was slightly greater than that of the VF. The analysers, however, provided substantially different results, especially between FibreShape Pro and QICPIC, although the general tendencies observed for the process-related changes were consistent. It can be concluded that the thermo-hydrolytic disintegration applied to the UF-bonded MDF did not cause any substantial changes in fibre geometry (i.e. fibre shortening). All fibre analysers are capable of detecting these changes, but the absolute values provided can vary widely between the instruments.

Effects of conditioning on the left ventricular function of young purebred Arabian horses.

The effects of conditioning on cardiac function in young horses is still unknown. For this reason, this study evaluated the left ventricular (LV) function of young horses by echocardiography after six weeks of conditioning. Fourteen untrained young purebred Arabian horses were evaluated at rest and after a stress test (ST) before and after a six-week conditioning program. There was an increase in V4 (p < 0.001) after conditioning, as well as a reduction in both heart rate (HR) at rest and peak HR during the ST (p < 0.001). There was also a reduction in internal diameter, along with an increase in interventricular septal, free wall and mean thicknesses and LV mass (p < 0.05). After the ST, the conditioned animals showed higher values of velocity time integral, stroke volume, systolic and cardiac indices, ejection (ET) and deceleration times (DT), end-diastolic volume, time to onset of radial myocardial velocity during early diastole and time to peak of transmitral flow velocity, in addition to reduced pre-ejection period (PEP), PEP/ET ratio and mean velocity of circumferential fiber shortening (p < 0.05). The conditioning protocol promoted physiological adaptations that indicate an improvement in the animals' aerobic capacity associated with an enhanced left ventricular function.

Investigation of friction and vibration performance of lithium complex grease containing candle soot on aviation electrical machine

The prolonged operation of the motor in the all-electric aircraft can cause the fragmentation and shortening of grease thickener fibers, ultimately resulting in the lubricating grease becoming ineffective. In order to avoid grease failure causing motor winding burnout, this paper uses a four-ball friction testing machine to test the tribological properties of six composite greases containing candle soot with different concentrations, and analyzes the changes in friction coefficient and wear diameter. In addition, by building a test platform for motor vibration and noise, this paper studies the influence of lithium complex grease on vibration and noise characteristics of aviation electrical machine at different propeller speeds. The results show that the addition of 0.04 wt% candle soot lithium grease has the best tribological properties and vibration inhibition properties, because the candle soot in the oil film changes the sliding friction into rolling friction in the contact area of some friction pair. The temperature rise test of aviation electrical machine shows that the lithium complex grease plays an active role in the heat dissipation performance of the high-speed rotating motor.

Kiosk 2R-TB-07 - In Vivo Quantification of the Regional Fiber Shortening and Laminar Thickening Strains of the Myocardium Using DENSE MRI

Kiosk 2R-TB-07 - In Vivo Quantification of the Regional Fiber Shortening and Laminar Thickening Strains of the Myocardium Using DENSE MRI

Human‐in‐the‐loop optimized rocker profile of running shoes to enhance ankle work and running economy

AbstractIncreasing the efficiency at which muscles generate mechanical power could improve running economy. A potential way to reduce muscle fiber shortening velocities and enhance energy storing of the Triceps Surae is changing their gear ratio at the ankle via optimization of shoe rollover profile. The aim of the current study was to individually optimize rollover profile of rocker shoes via human‐in‐the‐loop optimization to maximize positive ankle work to redistribute joint work from the hip and knee to the ankle and improve running economy. A total of 10 runners ran on a treadmill with experimental rocker shoes in which apex position and angle were optimized using an evolution algorithm to maximize positive ankle work. We compared experimental shoes with optimal settings, standard settings, and control shoes in terms of biomechanics and running economy. Optimal apex parameters differed considerably between participants. The optimal condition resulted in higher positive ankle work and a higher proportional share of the ankle in the total positive lower limb work compared to the standard condition. A difference in running economy between these conditions was not found. Human‐in‐the‐loop optimization can redistribute joint work from the hip and knee to the ankle by individually optimizing apex parameters. Although this did not improve running economy, the study showed that human‐in‐the‐loop optimization could improve the effectiveness of footwear with respect to the selected optimization parameter on an individual level.

Megakaryocyte-induced contraction of plasma clots: cellular mechanisms and structural mechanobiology

AbstractNonmuscle cell contractility is an essential feature underlying diverse cellular processes such as motility, morphogenesis, division and genome replication, intracellular transport, and secretion. Blood clot contraction is a well-studied process driven by contracting platelets. Megakaryocytes (MKs), which are the precursors to platelets, can be found in bone marrow and lungs. Although they express many of the same proteins and structures found in platelets, little is known about their ability to engage with extracellular proteins such as fibrin and contract. Here, we have measured the ability of MKs to compress plasma clots. Megakaryocytes derived from human induced pluripotent stem cells (iPSCs) were suspended in human platelet-free blood plasma and stimulated with thrombin. Using real-time macroscale optical tracking, confocal microscopy, and biomechanical measurements, we found that activated iPSC-derived MKs (iMKs) caused macroscopic volumetric clot shrinkage, as well as densification and stiffening of the fibrin network via fibrin-attached plasma membrane protrusions undergoing extension-retraction cycles that cause shortening and bending of fibrin fibers. Contraction induced by iMKs involved 2 kinetic phases with distinct rates and durations. It was suppressed by inhibitors of nonmuscle myosin IIA, actin polymerization, and integrin αIIbβ3–fibrin interactions, indicating that the molecular mechanisms of iMK contractility were similar or identical to those in activated platelets. Our findings provide new insights into MK biomechanics and suggest that iMKs can be used as a model system to study platelet contractility. Physiologically, the ability of MKs to contract plasma clots may play a role in the mechanical remodeling of intravascular blood clots and thrombi.

ANALYSIS OF THE FLOW OF A FIBROUS SUSPENSION IN A GRINDING PLANT IN THE PRODUCTION OF FINE CELLULOSE

Of the various methods for obtaining microcrystalline cellulose (mechanical, chemical, thermomechanical, planting cellulose in powder form from its solutions), the most common is acid hydrolysis of cellulose. The difficulty of obtaining MCC from vegetable raw materials is that, in addition to cellulose, it contains in its composition such compounds as lignin, hemicelluloses, various extractive substances and an insignificant percentage of minerals. When grinding plant fibers in an aqueous medium, both a purely mechanical process of changing the size and shape of fibers and a colloidal chemical process called fiber hydration occurs. Mechanical phenomena are expressed in the shortening of fibers, their longitudinal splitting into fibrils, an increase in the outer surface and the number of free hydroxyl groups on their surface. The term hydration refers to colloidal chemical phenomena that begin with the swelling of hydrophilic plant fibers.&#x0D; The paper considers methods for obtaining microcrystalline cellulose and factors influencing the development of a fibrous suspension isolated from coniferous wood species in a grinding plant with inertial bodies. Multiphysical models of the flow of fibrous suspension in the installation are constructed. A study of the effect of grinding a fibrous suspension on the process of obtaining fine cellulose was carried out. The indicators of the finished product are given. The change in the degree of polymerization of cellulose that has previously passed the grinding stage, with different degrees of grinding according to the Shopper-Rigler, is analyzed. Data on cost reduction and resource savings (acid concentration, temperature and processing time) in the process of obtaining fine cellulose are presented.

Artificial intelligence technology applied to an unoccluded catheter for recognition of hemodynamic changes

This study seeks to provide a reliable means for physicians to diagnose hemorrhagic complications associated with patent ductus arteriosus (PDA) in extremely low birth weight (ELBW) infants. We employ the YOLOv4 algorithm to analyze cardiac parameters from the echocardiography device's ultrasonic wave, such as left ventricular ejection time (LVET), left ventricular internal dimension-diastole (LVIDd), left ventricular internal dimension-systole (LVIDs), posterior wall thickness at end-systole (HES), and RR interval. The proposed model has achieved an impressive average detection accuracy of 89.4% for these five parameters. Additionally, the further evaluation of cardiac function can be done by deriving the end-systolic wall stress (ESWS) and left ventricle rate-corrected mean velocity of circumferential fiber shortening (mVcFc) values from these parameters. As a result, it indicates that the accuracy of ESWS and mVcFc values is 88.7% and 90.3%, respectively. With this deep learning-based approach, physicians can confidently evaluate the cardiac function of ELBW infants and diagnose PDA-related hemorrhagic complications.

Enzymatic pretreatment for cellulose nanofiber production: Understanding morphological changes and predicting reducing sugar concentration

Enzymatic pretreatment plays a crucial role in producing cellulose nanofibers (CNFs) before fibrillation. While previous studies have explored how treatment severity affects CNF characteristics, there remains a lack of suitable parameters to monitor real-time enzymatic processes and fully comprehend the link between enzymatic action, fibrillation, and CNF properties. This study focuses on evaluating the impact of enzyme charge (using a monocomponent endoglucanase) and treatment time on cellulose fiber morphology and reducing sugar generation. For the first time, a random forest (RF) model is developed to predict reducing sugar concentration based on easily measurable process conditions (e.g., stirrer power consumption) and fiber/suspension characteristics like fines content and apparent viscosity. Polarized light optical microscopy was found to be a suitable technique to evaluate the morphological changes that fibers experience during enzymatic pretreatment. The research also revealed that endoglucanases initially induce surface fibrillation, releasing fine fibers into the suspension, followed by fiber swelling and shortening. Furthermore, the effect of enzymatic pretreatment on resulting CNF characteristics was studied at two fibrillation intensities, indicating that a high enzyme charge and short treatment times (e.g., 90 min) are sufficient to produce CNFs with a nanofibrillation yield of 19–23 % and a cationic demand ranging from 220 to 275 μeq/g. This work introduces a well-modeled enzymatic pretreatment process, unlocking its potential and reducing uncertainties for future upscaling endeavors.

The Effect of Glycemic Control on Left Ventricular Function in Clinical and Experimental Diabetes

BackgroundGlycemic control in diabetes mellitus (DM) has not improved cardiovascular outcomes with normal left ventricular (LV) function. We assessed the effect on LV dysfunction using a canine model of LV dysfunction and DM, and in patients with DM and LV dysfunction. MethodsChronic LV dysfunction was produced by coronary microsphere embolization in 34 canines (15-25 kg). Following 8 weeks of stabilization, DM was induced in 24 canines and randomized to good or poor glycemic control for 3 months. Ten canines without DM were controls. Hemodynamic and Doppler echocardiographic data were obtained prior to and following pressure loading. We reviewed the Doppler-echocardiography at baseline and follow-up in 207 patients with DM with reduced ejection fraction (EF; median follow-up = 612 days) and 60 age- and sex-matched non-DM patients with normal EF. Laboratory results, medications, and incident adverse events from medical records were obtained. ResultsEF = 43.8% ± 11.2% for all canines at 8 weeks. Canines with poor glycemic control (hemoglobin [Hb]A1c = 8.05% ± 3.02%) demonstrated reduced LV mass and rate-corrected velocity of circumferential fiber shortening, compared to those with LV dysfunction (1.36 ± 0.73 vs 0.88 ± 0.13 circumference per second, P < 0.01). Good glycemic control (HbA1c = 3.88% ± 0.89%) demonstrated similar LV parameters, compared to controls (HbA1c = 2.99% ± 0.44%). EF was similar among groups. Patients with vs without DM were followed for up to 3 years. Patients with DM and poor glycemic control had reduced EF, lower rate-corrected velocity of circumferential fiber shortening = 0.93 ± 0.26 vs 1.11 ± 0.26, P < 0.001), and greater incidence of heart failure. ConclusionsPoor glycemic control had an adverse effect on preexisting LV dysfunction experimentally and in patients with type 2 diabetes.

Rapid restitution of contractile dysfunction by synthetic copolymers in dystrophin-deficient single live skeletal muscle fibers

Duchenne muscular dystrophy (DMD) is caused by the lack of dystrophin, a cytoskeletal protein essential for the preservation of the structural integrity of the muscle cell membrane. DMD patients develop severe skeletal muscle weakness, degeneration, and early death. We tested here amphiphilic synthetic membrane stabilizers in mdx skeletal muscle fibers (flexor digitorum brevis; FDB) to determine their effectiveness in restoring contractile function in dystrophin-deficient live skeletal muscle fibers. After isolating FDB fibers via enzymatic digestion and trituration from thirty-three adult male mice (9 C57BL10, 24 mdx), these were plated on a laminin-coated coverslip and treated with poloxamer 188 (P188; PEO75-PPO30-PEO75; 8400 g/mol), architecturally inverted triblock (PPO15-PEO200-PPO15, 10,700 g/mol), and diblock (PEO75-PPO16-C4, 4200 g/mol) copolymers. We assessed the twitch kinetics of sarcomere length (SL) and intracellular Ca2+ transient by Fura-2AM by field stimulation (25 V, 0.2 Hz, 25 °C). Twitch contraction peak SL shortening of mdx FDB fibers was markedly depressed to 30% of the dystrophin-replete control FDB fibers from C57BL10 (P < 0.001). Compared to vehicle-treated mdx FDB fibers, copolymer treatment robustly and rapidly restored the twitch peak SL shortening (all P < 0.05) by P188 (15 μM = + 110%, 150 μM = + 220%), diblock (15 μM = + 50%, 150 μM = + 50%), and inverted triblock copolymer (15 μM = + 180%, 150 μM = + 90%). Twitch peak Ca2+ transient from mdx FDB fibers was also depressed compared to C57BL10 FDB fibers (P < 0.001). P188 and inverted triblock copolymer treatment of mdx FDB fibers increased the twitch peak Ca2+ transient (P < 0.001). This study shows synthetic block copolymers with varied architectures can rapidly and highly effectively enhance contractile function in live dystrophin-deficient skeletal muscle fibers.

Probing the link between cortical inhibitory and excitatory processes and muscle fascicle dynamics

During movements, neural signals are translated into muscle fibre shortening, lengthening or they remain isometric. This study investigated cortical excitatory and inhibitory processes in relation to muscle fascicle dynamics during fixed-end rapid contractions. Fourteen adults performed submaximal and maximal ankle dorsiflexions. Single and paired pulse transcranial magnetic stimulation over the cortical representation projecting to the tibialis anterior (TA) was applied during rest, the activation and deactivation phase of contractions to test for short- (SICI) and long-interval intracortical inhibition (LICI) and intracortical facilitation (ICF). Ultrasound images were taken to measure muscle fascicle dynamics of the superficial (TASF) and deep (TADP) TA compartments. The results show significantly greater maximal shortening velocities (p = 0.003, d = 0.26, CI [4.89, 18.52]) and greater maximal fascicle shortening (p = 0.003, d = 0.86, CI [0.29, 3.13]) in TASF than TADP during submaximal dorsiflexions. Significantly lower SICI levels during activation compared to deactivation (p = 0.019, d = 1.12, CI [19.82, 1.76]) and at rest (p < 0.0001) were observed. ICF was significantly greater during activation (p = 0.03) than during rest while LICI did not modulate significantly. Maximal TASF but not TADP shortening velocity correlated with SICI levels at activation (p = 0.06) and with the rate of torque development (p = 0.02). The results suggest that SICI might be related to muscle fascicle behavior and that intracortical inhibition and excitation are phase-dependently modulated.

Chemopreventive effects of Xiang Sha Liu Jun Zi Tang on paclitaxel-induced leucopenia and neuropathy in animals.

Paclitaxel frequently induces peripheral neuropathy and myelosuppression during cancer treatment. According to the National Health Insurance Research Database of Taiwan, traditional Chinese medicine doctors widely use Xiang Sha Liu Jun Zi Tang (XSLJZT) to treat breast cancer patients who have received paclitaxel. We explored the combined therapeutic effects of XSLZJT with paclitaxel. XSLJZT did not exhibit significant cytotoxic effects on P388-D1 cells; however, the combination of XSLJZT (100 and 500mg/kg) with paclitaxel prolonged the survival rate in P388-D1 tumor-bearing mice compared to paclitaxel-only. In addition, XSLJZT was found to enhance white blood cells (WBC) counts and promote leukocyte rebound in paclitaxel-induced leukopenia in mice. XSLJZT also reduced paclitaxel-induced mechanical pain and inhibited c-Fos protein expression in the L4-6 spinal cords of Wistar rats. Moreover, paclitaxel-induced shortening of the nerve fibers of dorsal root ganglion cells was ameliorated by pre-treatment with XSLJZT. Therefore, we suggest that XSLJZT could be used as an adjunct for cancer patients, as the formula could decrease paclitaxel-induced neuropathy and myelosuppression.

Granger causality analysis of internal tongue muscles in tongue protrusion from diffusion and tagged MRI

The human tongue is a muscular hydrostat, comprising a group of orthogonally oriented and interdigitated muscles without skeletal support. Key characteristics of the tongue as a muscular hydrostat include that the tongue’s volume is constant, and any decrease in one dimension will be compensated by an increase in another dimension. This work aims to identify causal relationships among internal muscles in protrusive muscle contractions, which is vital to understand their underlying muscle coordination patterns. We investigated four muscles known to contribute to tongue protrusion, including transverse, verticalis, superior longitudinal, and genioglossus muscles. To capture tongue structure and function, we acquired diffusion MRI and tagged MRI to estimate the muscle fiber geometry of the four muscles and the motion patterns of tongue protrusion, respectively. We first computed Lagrangian strains along muscle fiber direction in each voxel, reflecting muscle fiber shortening. Average strain values in each muscle, defined by a vocal tract atlas, were then input into a linear vector autoregression Granger causality model, to investigate their causal relationships. Our findings on the strain patterns over time as well as the pairwise causal relationships were consistent in part with the muscular hydrostat theory, which helps elucidate the tongue muscle coordination patterns.

Passive force enhancement is not abolished by shortening of single fibres.

Passive force enhancement is defined as the increase in steady-state passive force following active muscle stretching compared to the corresponding passive force following passive muscle stretching. This mechanical property has been discovered just two decades ago (Herzog & Leonard, 2002), and has been associated with contributing to the residual force enhancement property, stability of sarcomeres, and preventing over-stretching during eccentric contractions. The molecular mechanisms underlying passive force enhancement development and abolishment remain unknown. An incidental observation on cat soleus muscle led to the speculation that passive force enhancement could be abolished instantaneously when the actively stretched muscle was deactivated and then passively shortened to its pre-stretched length (Herzog et al., 2003). We tested this hypothesis systematically using single skinned fibres from rabbit psoas. However, initial results led to the rejection of this hypothesis. Rather, we found that passive force enhancement increased following a shortening-stretch cycle of fibres to their pre-stretched length (2.4 µm), and back. Furthermore, we observed that the passive force enhancement increased by 70-106% when the shortening and subsequent stretch to the original length (3.6 µm) increased in duration (200 ms, 6 s, and 14 s). When reversing the order of the shortening-stretch experiments from slowest to fastest, the general result was the same as that of the primary experiment. These findings indicated that passive force enhancement increases during a shortening-stretch cycle, and that this increase is time-dependent. We propose that this increase in passive force enhancement may be caused by titin; specifically, with a refolding of titin's immunoglobulin domains that were unfolded during the active fibre stretching that produced the residual and passive force enhancement. Using fluorescent antibody labeling of selected titin segments, we will be testing this hypothesis in the near future.

Metabolic reprogramming underlies cavefish muscular endurance despite loss of muscle mass and contractility

Physical inactivity is a scourge to human health, promoting metabolic disease and muscle wasting. Interestingly, multiple ecological niches have relaxed investment into physical activity, providing an evolutionary perspective into the effect of adaptive physical inactivity on tissue homeostasis. One such example, the Mexican cavefish Astyanax mexicanus, has lost moderate-to-vigorous activity following cave colonization, reaching basal swim speeds ~3.7-fold slower than their river-dwelling counterpart. This change in behavior is accompanied by a marked shift in body composition, decreasing total muscle mass and increasing fat mass. This shift persisted at the single muscle fiber level via increased lipid and sugar accumulation at the expense of myofibrillar volume. Transcriptomic analysis of laboratory-reared and wild-caught cavefish indicated that this shift is driven by increased expression of pparγ-the master regulator of adipogenesis-with a simultaneous decrease in fast myosin heavy chain expression. Exvivo and invivo analysis confirmed that these investment strategies come with a functional trade-off, decreasing cavefish muscle fiber shortening velocity, time to maximal force, and ultimately maximal swimming speed. Despite this, cavefish displayed a striking degree of muscular endurance, reaching maximal swim speeds ~3.5-fold faster than their basal swim speeds. Multi-omic analysis suggested metabolic reprogramming, specifically phosphorylation of Pgm1-Threonine 19, as a key component enhancing cavefish glycogen metabolism and sustained muscle contraction. Collectively, we reveal broad skeletal muscle changes following cave colonization, displaying an adaptive skeletal muscle phenotype reminiscent to mammalian disuse and high-fat models while simultaneously maintaining a unique capacity for sustained muscle contraction via enhanced glycogen metabolism.

МОБИЛЬНОЕ ПРИЛОЖЕНИЕ В ПРОГНОЗИРОВАНИИ СИСТОЛИЧЕСКОЙ ФУНКЦИИ ЛЕВОГО ЖЕЛУДОЧКА ПРИ ЛЕЧЕНИИ РАКА МОЛОЧНОЙ ЖЕЛЕЗЫ АНТРАЦИКЛИНАМИ

Purpose. To evaluate the effect of complex treatment of breast cancer (BC) on the parameters of systolic myocardial function, and the efficiency of the prescription of cardiotropic therapy (CT) – a fixed combination of valsartan and carvedilol – in the prevention of the identified changes. To develop a mobile application, namely, an electronic statistical calculator for calculating the left ventricular ejection fraction by Simpson during BC treatment with anthracyclines, using the baseline anthropometric and instrumental data of the patient. Methods. We evaluated the cardiovascular health of 100 women who received complex treatment of BC. The patients were divided into three groups, depending on the presence of arterial hypertension and the prescription of CT. In the study, all women received a complex evaluation of the cardiovascular health at the beginning and at the end of BC treatment Results. In the non-CT group af ter the end of complex BC treatment the following was found: a decrease in the shortening fraction (FS) from 41.0 (38.0; 45.0)% to 38.0 (35.0; 43.0)%, (p &lt; 0.05), in ejection fraction (EF) by Teinholz from 72.0 (69.0; 76.0)% to 68.0 (64.0; 73.0)%, (p &lt; 0.05); in ejection fraction by Simpson from 66.0 (62.0; 71.0)% to 60.0 (57.0; 66.0)%, (p &lt; 0.05); an increase in the vagosympathetic interaction LF/HF index (ratio of lowfrequency (LF) to high-frequency (HF) components) from 0.8 (0.7; 1.0) to 1.05 (0.8; 1.2), (p &lt; 0.05); reduction of brachial artery diameter change from 12.5 (11.0; 16.0)% to 9.0 (6.0; 12.0)%, (p &lt; 0.05). A model of the prognosis of EF by Simpson during BC treatment was proposed, which included a total dose of doxorubicin calculated per body surface area, early diastolic rate of transtricuspid blood flow, diameter of the trunk of the pulmonary artery, the rate of circular shortening of myocardial fibers, thickness of the intima-media complex of the left carotid arteries, HF, % of brachial artery diameter change. The prognosis model formed the basis for the development of the mobile application for predicting left ventricular systolic function during BC treatment with anthracyclines. We proposed a model for prediction of LVEF by Simpson against during breast cancer treatment, which included the total doxorubicin dose calculated per body surface area, early diastolic rate of transtricuspidal blood flow, pulmonary artery trunk diameter, myocardial fiber circular shortening rate, left carotid artery intima-media complex thickness, HF, percentage of brachial artery diameter change. The prognostic model formed the basis for the development of the mobile application for predicting left ventricular systolic function during BC treatment with anthracyclines.

Evaluation of right ventricular strain in two separate cohorts with precapillary pulmonary hypertension.

Evaluation for right ventricular (RV)dysfunction is an important part of risk assessment in care of patients with pulmonary hypertension (PH) as it is associated with morbidity and mortality. Echocardiography provides a widely available and acceptable method to assess RV function. RV global longitudinal strain (RVGLS), a measure of longitudinal shortening of RV deep muscle fibers obtained by two-dimensional echocardiography, was previously shown to predict short-term mortality in patients with PH. The purpose of the current study was to assess the performance of RVGLS in predicting 1-year outcomes in PH. We retrospectively identified 83 subjects with precapillary PH and then enrolled 50 consecutive prevalent pulmonary arterial hypertension (PAH) subjects into a prospective validation cohort. Death as well as combined morbidity and mortality events at 1 year were assessed as outcomes. In the retrospective cohort, 84% of patients had PAH and the overall 1-year mortality rate was 16%. Less negative RVGLS was marginally better than tricuspid annular plane systolic excursion(TAPSE)as a predictor for death. However, in the prospective cohort, 1-year mortality was only 2%, and RVGLS was not predictive of death or a combined morbidity and mortality outcome. This study supports that RV strain and TAPSE have similar 1-year outcome predictions but highlights that low TAPSE or less negative RV strain measures are often false-positive in a cohort with low baseline mortality risk. While RV failure is considered the final common pathway for disease progression in PAH, echocardiographic measures of RV function may be less informative of risk in serial follow-up of treated PAH patients.

Is perfusion index a surrogate indicator of left ventricular contractility in neonates? A prospective study.

Noninvasive blood pressure monitoring may not accurately reflect cardiac contractility in neonates due to low vascular tone. The perfusion index (PI) is a noninvasive method of assessing the strength of peripheral pulses. It is shown to have a significant correlation with the left ventricular output. This prospective study estimates the correlation between PI and cardiac contractility in neonates. All hemodynamically stable neonates who were on substantial enteral feeds and not on any respiratory or inotropic support underwent measurement of PI and echocardiography examination. Various indices of left ventricular contractility were estimated, and the correlation coefficient between them and PI was determined. Fifty-six neonates were studied. The median (interquartile range [IQR]) PI was 1.5 (1.25-1.75). The median (IQR) PI in preterm neonates was 1.5 (1.2-1.8) and that in term neonates was 1.8 (1.25-2.7) (P = 0.064). PI had a correlation of 0.205 with fractional shortening (P = 0.129) and 0.13 with left ventricular ejection fraction (P = 0.821). The Spearman's correlation coefficient between PI and velocity of circumference fiber shortening was 0.009 (P = 0.945). The Spearman's correlation coefficient between PI and cardiac output was -0.115 (P = 0.400). The PI does not correlate with left ventricular contractility parameters in neonates.