Cell Deformability Research Articles

LysSYL: a broad-spectrum phage endolysin targeting Staphylococcus species and eradicating S. aureus biofilms

BackgroundStaphylococcus aureus and its single or mixed biofilm infections seriously threaten global public health. Phage therapy, which uses active phage particles or phage-derived endolysins, has emerged as a promising alternative strategy to antibiotic treatment. However, high-efficient phage therapeutic regimens have yet to be established.ResultsIn this study, we used an enrichment procedure to isolate phages against methicillin-resistant S. aureus (MRSA) XN108. We characterized phage SYL, a new member of the Kayvirus genus, Herelleviridae family. The phage endolysin LysSYL was expressed. LysSYL demonstrated stability under various conditions and exhibited a broader range of efficacy against staphylococcal strains than its parent phage (100% vs. 41.7%). Moreover, dynamic live/dead bacterial observation demonstrated that LysSYL could completely lyse MRSA USA300 within 10 min. Scan and transmission electron microscopy revealed evident bacterial cell perforation and deformation. In addition, LysSYL displayed strong eradication activity against single- and mixed-species biofilms associated with S. aureus. It also had the ability to kill bacterial persisters, and proved highly effective in eliminating persistent S. aureus when combined with vancomycin. Furthermore, LysSYL protected BALB/c mice from lethal S. aureus infections. A single-dose treatment with 50 mg/kg of LysSYL resulted in a dramatic reduction in bacterial loads in the blood, liver, spleen, lungs, and kidneys of a peritonitis mouse model, which resulted in rescuing 100% of mice challenged with 108 colony forming units of S. aureus USA300.ConclusionsOverall, the data provided in this study highlight the strong therapeutic potential of endolysin LysSYL in combating staphylococcal infections, including mono- and mixed-species biofilms related to S. aureus.

Photocell-Based Optofluidic Device for Clogging-Free Cell Transit Time Measurements.

Measuring the transit time of a cell forced through a bottleneck is one of the most widely used techniques for the study of cell deformability in flow. It in turn provides an accessible and rapid way of obtaining crucial information regarding cell physiology. Many techniques are currently being investigated to reliably retrieve this time, but their translation to diagnostic-oriented devices is often hampered by their complexity, lack of robustness, and the bulky external equipment required. Herein, we demonstrate the benefits of coupling microfluidics with an optical method, like photocells, to measure the transit time. We exploit the femtosecond laser irradiation followed by chemical etching (FLICE) fabrication technique to build a monolithic 3D device capable of detecting cells flowing through a 3D non-deformable constriction which is fully buried in a fused silica substrate. We validated our chip by measuring the transit times of pristine breast cancer cells (MCF-7) and MCF-7 cells treated with Latrunculin A, a drug typically used to increase their deformability. A difference in transit times can be assessed without the need for complex external instrumentation and/or demanding computational efforts. The high throughput (4000-10,000 cells/min), ease of use, and clogging-free operation of our device bring this approach much closer to real scenarios.

Abstract 3384: Rapid and automated tumor cell phenotyping based on annexin-mediated enforce blebbing response

Abstract Introduction: Accumulating evidence supports the tight correlation between the physical characteristics of cells (including morphology, mechanical, and electrical properties) with the progression of cancer. Cellular blebbing, a distinctive feature observed during apoptosis and cell migration, has gained significant recognition. However, existing tools such as atomic force microscopy and optical tweezers have limitations in terms of throughput and complexity. Microfluidics has emerged as a promising technology to overcome these limitations. Methods: In this study, we developed a novel microfluidic device with a double-layer compression mechanism to induce controlled blebbing of cells. We implemented a convolution-based tracing program to enhance the accuracy and efficiency of cell area measurement. The device was used to examine the enforced blebbing response of two human breast cancer cell lines (MDA-MB-231 and MCF-7) and investigate the potential of blebbing as a marker for drug resistance using a human lung cancer cell line (HCC4006). Additionally, we elucidated the role of annexin-6 (A6) in enforced blebbing and its underlying mechanism. Results: Our microfluidic device successfully implemented a double-layered design that induced cell deformation through compression from the second pressurized polydimethylsiloxane layer. The findings revealed that highly invasive cell lines, such as MDA-MB-231 and osimertinib-resistant HCC4006, required significantly higher critical compression levels compared to their non-invasive counterparts (MCF-7 cell line) or osimertinib-sensitive cells. Moreover, the drug-resistant groups exhibited a greater compression strain requirement for blebbing compared to the control group, indicating their enhanced resilience against disruptive forces and superior survivability. Prior studies have demonstrated that A6 protein is recruited to the site of membrane injury and facilitates the formation of blebs, thereby contributing to cellular repair processes. Our further investigation into the role of A6 protein demonstrated its involvement in cell blebbing. Knockdown of A6 resulted in a notable 27% reduction in cellular volume, reflecting reduced intracellular pressure, and a corresponding 1.7-fold increase in the critical compressive strain necessary for inducing blebbing. Conclusion: Our microfluidic device allows for rapid and simultaneous testing and automated analysis of hundreds of cells, making it suitable for applications such as cell sorting, highly invasive and drug-resistant cancer cell detection, without the need for labeling. Furthermore, it serves as a powerful tool for fundamental studies of membrane and cytoskeleton dynamics. The label-free nature of the device, coupled with its high throughput capabilities, highlights its potential in future applications, including cancer monitoring and drug-resistance screening. Citation Format: Wei Huang, Zheng Wang, Dennis Wai-Yin Au, Bingxian Tang, Baiqian Qi, William C. Cho, Yuan Lin. Rapid and automated tumor cell phenotyping based on annexin-mediated enforce blebbing response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3384.

Blood physiology. erythrocyte based on the plenary lecture at the XXIV congress of the physiological society named after. I. P. Pavlova…

Human red blood cells have a complex system for regulating cell volume and deformability. This is absolutely necessary to ensure good blood rheology both in large vessels and in the capillary network. The review examines the features of the erythrocyte structure that provide good gas transport functions and excellent blood rheology, despite the fact that erythrocytes occupy 40% of the blood volume. Providing these properties requires the participation of a number of metabolic systems, which allows the red blood cell to work effectively in the bloodstream for 100–120 days without the synthesis of new proteins.

The RoxyScan is a novel measurement of red blood cell deformability under oxidative and shear stress

Exposure to both oxidative and shear stress, a condition that the red blood cell (RBC) continuously experiences in the circulation in vivo can be mimicked in a Couette type viscometer and monitored by ektacytometry. RBCs maintain their deformation and orientation under shear stress and oxidative stress until a threshold is reached at which these conditions appear to overwhelm the elaborate and complex pathways that maintain a proper redox environment in the cell. Oxidative stress under shear alters the ability of the cell to deform, changes cell morphology, its orientation in the shear stress field, and appears to alter intracellular and membrane characteristics. The application of the RoxyScan technology allows the comparison of oxidant effects and the role of antioxidant systems. This provides the opportunity to study the ability of RBC to deal with oxidative stress in various conditions, including RBC disorders such as sickle cell disease (SCD).

Microfluidic device featuring micro-constrained channels for multi-parametric assessment of cellular biomechanics and high-precision mechanical phenotyping of gastric cells

BackgroundCellular biomechanics plays a significant role in the regulation of cellular physiological and pathological processes. In recent years, multiple methods have been developed to evaluate cellular biomechanics, such as atomic force microscopy (AFM), micropipette aspiration, and magnetic tweezers. However, most of these methods only focus on a single parameter and cannot automate the process at a high-efficiency level. A novel microfluidic method is necessary to achieve the simultaneous multi-parametric measurement of cellular biomechanics and high-precision cellular mechanical phenotyping at high throughput. ResultsTo tackle the issue concerning the low-throughput and cellular single-parameter evaluation, we designed and fabricated a microfluidic chip featuring multiple micro-constrained channels structure, providing a simultaneous multi-parametric assessment of cellular biomechanics, including elastic modulus, recovery capability, and deformability. We compared the biomechanical properties of normal human gastric mucosal epithelial cells (GES-1) and human gastric cancer cells (AGS and MKN-45) by the chip. Results demonstrated that the elastic modulus of GES-1, AGS, and MKN-45 cells decreased sequentially, which was the opposite of their invasiveness and metastasis potential, suggesting the inverse correlation between cellular elastic modulus and malignancy. Meanwhile, the recovery capability and deformability of GES-1, AGS, and MKN-45 cells increased sequentially, demonstrating the positive correlation between cellular deformability and malignancy. Furthermore, multiple parameters were used to distinguish gastric cancer cells from normal gastric cells via machine learning. An accuracy of over 94.8% for identifying gastric cancer cells was achieved. SignificanceThis study provides a deep insight into the biophysical mechanism of gastric cancer metastasis at the single-cell level and possesses great potential to function as a valuable tool for single-cell analysis, thereby facilitating high-precision and high-throughput discrimination of cellular phenotypes that are not easily discernible through single-marker analysis.

Omega-3 supplementation changes the physical properties of leukocytes but not erythrocytes in healthy individuals: An exploratory trial

n3-PUFA impact health in several ways, including cardiovascular protection and anti-inflammatory effects, but the underlying mechanisms are not fully understood. In this exploratory study involving 31 healthy subjects, we aimed to investigate the effects of 12 weeks of fish-oil supplementation (1500 mg EPA+DHA/day) on the physical properties of multiple blood cell types. We used deformability cytometry (DC) for all cell types and Laser-assisted Optical Rotational Red Cell Analysis (Lorrca) to assess red blood cell (RBC) deformability. We also investigated the correlation between changes in the physical properties of blood cells and changes in the Omega-3 Index (O3I), defined as the relative content of EPA+DHA in RBCs. Following supplementation, the mean±SD O3I increased from 5.3 %±1.5 % to 8.3 %±1.4 % (p < 0.001). No significant changes in RBC properties were found by both techniques. However, by DC we observed a consistent pattern of physical changes in lymphocytes, neutrophils and monocytes. Among these were significant increases in metrics correlated with the cells’ deformability resulting in less stiff cells. The results suggest that leukocytes become softer and have an increased ability to deform under induced short-term physical stress such as hydrodynamic force in the circulation. These changes could impact immune function since softer leukocytes can potentially circulate more easily and could facilitate a more rapid response to systemic inflammation or infection. In conclusion, fish-oil supplementation modulates some physical properties of leukocyte-subfractions, potentially enhancing their biological function. Further studies are warranted to explore the impact of n3-PUFA on blood cell biology, particularly in disease states associated with leukocyte dysregulation.

Deformation and Transformation Textures in the NaMgF3 Neighborite—Post-Perovskite System

The D″ region of the lower mantle, which lies just above the core–mantle boundary, is distinct from the bulk of the lower mantle in that it exhibits complex seismic heterogeneity and seismic anisotropy. Seismic anisotropy in this region is likely to be largely due to the deformation-induced texture (crystallographic preferred orientation) development of the constituent mineral phases. Thus, seismic anisotropy can provide a marker for deformation processes occurring in this dynamic region of the Earth. Post-perovskite-structured (Mg,Fe)SiO3 is believed to be the dominant mineral phase in many regions of the D”. As such, understanding deformation mechanisms and texture development in post-perovskite is important for the interpretation of observed seismic anisotropy. Here, we report on high-pressure diamond anvil cell deformation experiments on NaMgF3 neighborite (perovskite structure) and post-perovskite. During deformation, neighborite develops a 100 texture, as has been previously observed, both in NaMgF3 and MgSiO3 perovskite. Upon transformation to the post-perovskite phase, an initial texture of {130} at high angles to compression is observed, indicating that the {100} planes of perovskite become the ~{130} planes of post-perovskite. Further compression results in the development of a shoulder towards (001) in the inverse pole figure. Plasticity modeling using the elasto-viscoplastic self-consistent code shows this texture evolution to be most consistent with deformation on (001)[100] with some contribution of glide on (100)[010] and (001)&lt;110&gt; in NaMgF3 post-perovskite. The transformation and deformation mechanisms observed in this study in the NaMgF3 system are consistent with the behavior generally observed in other perovskite–post-perovskite systems, including the MgSiO3 system. This shows that NaMgF3 is a good analog for the mantle bridgmanite and MgSiO3 post-perovskite.

Improvement of tensile properties through Nb addition and heat treatment in additively manufactured 316L stainless steel using directed energy deposition

Metal additive manufacturing (AM) has been applied in various fields because it allows the manufacture of parts with complex shapes. In this study, 316 L stainless steel specimens with 0 and 2 wt% Nb were fabricated using direct energy deposition, and heat treatment was performed at various temperatures. The addition of Nb changed the microstructure of the steel, including the grain size and Nb segregation. When heat treatment was performed, microstructural evolution of the cell boundary, dislocation density, and deformation twin density occurred. These microstructural changes improved the tensile properties of the heat-treated specimens containing Nb. The yield strength, tensile strength, and elongation of the specimens containing Nb with heat treatment at 800 °C were 530 MPa, 757 MPa, and 39%, respectively, which represent great improvements compared to specimens without Nb. These results show that the addition of Nb to 316 L stainless steel together with heat treatment at an appropriate temperature endow the additively manufactured stainless steel with excellent tensile properties.

A Microfluidic Perfusion Culture Setup to Investigate Cell Migration in 3D Constrictions

AbstractCell migration is a fundamental process underlying the morphological maturation of organs, but also in disease‐related conditions such as cancer. Cells are able to migrate through crowded space and a tight extracellular matrix (ECM). Passing through a constriction, a cell deforms strongly, including its nucleus. Such nuclear deformation can lead to changes in the 3D‐genomic architecture, and putatively, DNA methylation. However, the specific effects of deformation on cells are not well understood. It is highly desired to establish an ex vivo methodology to induce well‐defined cell deformation in complex geometrical constrictions. This study introduces a microfluidic system for the study of migrating cells in precisely controlled geometrical confinement. A procedure for coating, seeding of cerebellar granule cells, and perfusion culture is presented. By leveraging direct laser writing, channels with smooth, anisotropically curved surfaces on the cell‐scale can be fabricated. The system consists of constriction channels with a radius of 2 or 4 µm for the cells to pass through. This corresponds to a compression of the nucleus to 3.5% and 14.2% of its undeformed cross‐sectional area, respectively. The system can be used to investigate the influence of confinement geometry on the migration behavior and transcriptome of various cell types.

SARS-CoV-2 Infection and Anemia-A Focus on RBC Deformability and Membrane Proteomics-Integrated Observational Prospective Study.

The multifaceted impact of COVID-19 extends beyond the respiratory system, encompassing intricate interactions with various physiological systems. This study elucidates the potential association between SARS-CoV-2 infection and anemia, with a particular emphasis on the deformability of red blood cells (RBCs), stability of hemoglobin, enzymatic activities, and proteomic profiles. The study encompasses a cohort of 74 individuals, including individuals positive for COVID-19, a control group, and patients with other viral infections to discern the specific effects attributable to COVID-19. The analysis of red blood cells was focused on deformability measured by osmotic gradient ektacytometry, hemoglobin stability, and glycolytic enzyme activity. Furthermore, membrane proteins were examined using advanced proteomics techniques to capture molecular-level changes. Findings from the study suggest a correlation between anemia and exacerbated outcomes in COVID-19 patients, marked by significant elevations in d-dimer, serum procalcitonin, creatinine, and blood urea nitrogen (BUN) levels. These observations suggest that chronic kidney disease (CKD) may play a role in the development of anemia in COVID-19 patients, particularly those of advanced age with comorbidities. Furthermore, the proteomic analyses have highlighted a complex relationship between omics data and RBC parameters, enriching our understanding of the mechanisms underlying the disease. This research substantiates the complex interrelationship between COVID-19 and anemia, with a specific emphasis on the potential repercussions of SARS-CoV-2 infection on RBCs. The findings contribute to the growing body of evidence supporting the extensive impact of COVID-19 on RBCs.

Rheological properties of blood in multiple myeloma patients.

Multiple myeloma (MM) is considered to be one of the hematological malignancies formed by excessive and abnormal proliferation of plasmocytes. Among other parameters, several blood tests are used to diagnose multiple myeloma. The hemorheological profile in multiple myeloma is not widely studied. Hemorheology includes the study of measuring the deformability and aggregation of erythrocytes, blood viscosity, and sedimentation rate. The degree of deformability of blood cells is necessary to maintain proper vital functions. Proper deformability of red blood cells ensures proper blood circulation, tissue oxidation and carbon dioxide uptake. The aim of the study was to compare morphology and blood rheology parameters in patients with MM and healthy individuals. The study included 33 patients with MM, and 33 healthy subjects of the same age. The hematological blood parameters were evaluated using ABX MICROS 60 hematology analyzer. The LORCA Analyzer to study erythrocyte aggregation and deformability. Patients with MM had lower red blood cells count (RBC) (9.11%) (p < 0.001) and half time of total aggregation (T1/2) (94.29%) (p < 0.001) values and higher mean corpuscular volume (MCV) (5.50%) (p < 0.001), aggregation index (AI) (68.60%) (p < 0.001), total extent of aggregation (AMP) (87.92%) (p < 0.001) values than the healthy control group. Aggregation in patients with MM is different compared to healthy individuals. It was observed that the percentage of cell aggregation is almost 50% higher than in the control group. The study of morphology, aggregation and deformability of erythrocytes in patients with suspected MM may be helpful in making clinical decisions.

Red cell membranopathies: Case series and review of literature

Inherited disorders affecting the red blood cell (RBC) membrane result from mutations in membrane or skeletal proteins. Such mutations can impede red cell deformability, leading to a shortened lifespan and early removal of erythrocytes from circulation. This, in turn, results in anemia and jaundice. Hereditary spherocytosis (HS), hereditary elliptocytosis, hereditary ovalocytosis, and hereditary stomatocytosis are examples of these disorders, with HS being the most prevalent form of inherited hemolytic anemia. Disorders of the RBC membrane may stem from structural or transport functional changes, but they inevitably lead to clinical symptoms of hemolytic anemia. Accurate diagnosis is crucial to avoid complications or inappropriate treatment as management varies depending on pathophysiology. In this review, we describe few cases of different types of RBC membrane disorders with variable age of presentation, emphasizing the significance of correct approach, limitations of certain investigations and the need for genetic test to reach a precise diagnosis.

Sustainable use of plastic-derived nanocarbons as a promising larvicidal and growth inhibitor agent towards control of mosquitoes

Nanoscale carbon was obtained from six widely used plastics (PET, HDPE, PVC, LDPE, PP and PP) via thermal degradation (600 °C) under inert atmosphere. The thermally degraded products were processed through bath sonication followed by lyophilisation and the same was characterized through proximate analysis, UV–Vis spectroscopy, Scanning electron micrograph (SEM) with energy dispersive X-ray (EDX) analysis, Transmission electron micrograph (TEM), Dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). A series of aqueous solution of nanoscale carbon (5–30 mg/L) were prepared and same were used as both mosquito growth inhibitor and larvicidal agent against 3rd and 4th instar larvae of Culex pipiens. The significant percent mortality results were recorded for LDPE (p < 0.007) with average particle size of 3.01 nm and 62.95 W% of carbon and PS (p < 0.002) with average particle size of 12.80 nm and 58.73 W% of carbon against 3rd instar larvae, respectively. Similarly, for 4th instar larvae, both significant pupicidal and adulticidal activity were also recorded for PET (F = 24.0, p < 0.0001 and F = 5.73, p < 0.006), and HDPE (F = 26.0, p < 0.0001) and F = 5.30, p < 0.008). However, significant pupicidal activity were observed for PVC (F = 6.90, p < 0.003), and PS (F = 21.30, p < 0.0001). Histological, bio-chemical and microscopic studies were revealed that nanoscale carbon causes mild to severe damage of external and internal cellular integrity of larvae. However, nanoscale carbon does not exhibit any chromosomal abnormality and anatomical irregularities in Allium cepa and Cicer arietinum, respectively. Similarly, non-significant results with respect to blood cell deformation were also recorded from blood smear of Poecilia reticulata. Therefore, it can be concluded that plastic origin nanoscale carbon could be a viable sustainable nano-weapon towards control of insects.

Optofluidic-based deformability cytometry: Characterizing erythrocyte elasticity and assessing storage quality

Erythrocyte elasticity is an inherent, label-free marker for both physiological and pathological changes in erythrocytes, serving as a criterion for assessing the quality and suitability of stored blood. Although varieties of cell elasticity measurement techniques have been proposed, a small sample, non-contact, and continuous method is still in need. This article introduces an optofluidic-based deformability cytometry (O-DC) for characterizing erythrocyte elasticity, combining non-contact optical force with microfluidic technology. A tightly focused laser beam optically traps an erythrocyte, and the flow force induces cell deformation, allowing for elasticity characterization through force-dependent elongation. The O-DC technique offers high accuracy and desirable throughput for cell elasticity characterization, facilitated by quasi-static stretching and continuous cell delivery. The characterization throughput of O-DC is ∼3 cells per second at a flow rate of 30 μL/h and a laser power of 200 mW. Fresh erythrocytes exhibit measured elastic strains of 15.4–27.8% across flow rates of 10–30 μL/h, with an estimated elastic modulus of 2.6±0.3 μN/m. Using O-DC, the elasticity trend of erythrocytes stored for 0–6 weeks was analyzed, with their average elastic modulus increasing from 2.6±0.3 μN/m to 6.1±0.8 μN/m as the storage time increased. Our study highlights the potential of O-DC in clinical diagnostics and biomechanical research applications.

Enhanced forward scattering of a cell in line optical tweezers with an astigmatic beam.

The line optical tweezers (LOT) has been proven to be an alternative technique to manipulating the biological cells because of the bigger potential compared with traditional optical tweezers with a highly focused spot. We deduce the 4 × 4 optical matrix of the astigmatic LOT to investigate the optical characteristics related to the systematic parameters. The comparison of the initial and scattered electric fields by the cell under the astigmatic and stigmatic LOT is implemented to illustrate that the forward scattered light from the astigmatic LOT is much stronger than that from the stigmatic LOT, so as to the cell deformations. It is demonstrated that the astigmatic LOT could provide a more efficient way to deform the cell not only in the focal plane, but also along the optical axis to screen large biomaterials in biomechanics.

The psychological intervention and clinical efficacy of Rosenthal effect and acupuncture bleeding on middle-aged and young patients with sudden hearing loss.

Combining traditional Chinese medicine theory and modern medical knowledge, this study explores the pathogenesis of sudden hearing loss in middle-aged and young people. Sixty-four young and middle-aged patients with sudden hearing loss who visited a public tertiary hospital in China are chosen as experimental objects. All experimental patients are broken into an experimental group (n = 32) and a control group (n = 32). The control group receive conventional Western medicine treatment regimen. The experimental group receive select acupoint acupuncture and bloodletting combined with Rosenthal effect for psychological intervention, and both groups have a treatment course of 14 days. The changes in the patient's condition before and after treatment are observed, and the differences in hearing threshold values, tinnitus, and dizziness clinical efficacy before and after treatment are observed and recorded. It evaluates the efficacy using the Anxiety, Depression Scale, and Hope Scale and statistically analyzes the data. The dizziness score of the experimental group decreased rapidly, the treatment onset time was shorter, and the improvement effect on dizziness symptoms was better (P < .05). After 1 month of intervention treatment, the intervention of the experimental group was better (P < .05). The hope level and self-efficacy of both groups of patients were raised in contrast with before treatment (P < .05). After 1 month, the intervention effect of the experimental group was more significant (P < .01). Both groups could improve patient ear blood circulation, but the experimental group had lower plasma viscosity, hematocrit, and red blood cell aggregation index, higher red blood cell deformation index, and more significant improvement effect (P < .05). The effective rates of improving hearing and tinnitus in the experimental group reached 87.5% and 81.5%, and the clinical treatment efficacy was better than that in the control group (P < .05). The level of depression and anxiety in the experimental group remained relatively stable, while that in the control group showed a significant rebound (P < .05). In conclusion, both groups had a certain effect in treating sudden deafness, both of which could effectively improve the patient's hearing. But in contrast with the control group, the experimental group had better clinical efficacy, higher safety, and better psychological intervention results, which is worthy of clinical promotion.

Mechanical advantage of subsidiary cells depends on the stomatal complex structure

Structural features of stomatal complexes influencing the mechanical advantage of subsidiary cells were studied. Light, scanning and transmission electron microscopy were used to research the morphology of Fagraea ceilanica stomatal complexes. Their guard cells are located on subsidiary cells. The walls of the subsidiary cells are thickened unevenly. The inner tangential walls are thin and most extensive as compared to other walls of these cells. The data obtained allowed a 3D model of F. ceilanica stomatal complex to be constructed. To elucidate the interaction between the guard and subsidiary cells during stomatal movements, we have applied modelling using the finite-element method. According to the modelling results, the mechanical advantage of the subsidiary cells depends on mutual location of the guard and subsidiary cells, uneven thickening, area and rigidity of the subsidiary cell walls and presence of substomatal chambers, into which the inner tangential walls of the subsidiary cells can bulge when turgor pressure in these cells increases. The modelling results were confirmed by the observed deformations in actual stomatal complex cells of F. ceilanica. The decrease in mechanical advantage of the subsidiary cells ensures stoma opening in the conditions of excessive saturation of the epidermis with water, for example, in the conditions of tropical rainforests.

Computing Sickle Erythrocyte Health Index on quantitative phase imaging and machine learning

Sickle cell disease (SCD) is a genetic disorder characterized by abnormal hemoglobin and deformation of red blood cells (RBCs), leading to complications and reduced life expectancy. This study developed an in vitro assessment, the Sickle Erythrocyte Health Index, using quantitative phase imaging (QPI) and machine learning to model the health of RBCs in people with SCD. The health index combines assessment of cell deformation, sickle-shaped classification, and membrane flexibility to evaluate erythrocyte health. Using QPI and image processing, the percentage of sickle-shaped cells and membrane flexibility were quantified. Statistically significant differences were observed between individuals with and without SCD, indicating the impact of underlying pathophysiology on erythrocyte health. Additionally, sodium metabisulfite led to an increase in sickle-shaped cells and a decrease in flexibility in the sickle cell blood samples. Based on these findings, two approaches were used to calculate the Sickle Erythrocyte Health Index: one using hand-crafted features and one using learned features from deep learning models. Both indices showed significant differences between non-SCD and SCD groups and sensitivity to changes induced by sodium metabisulfite. The Sickle Erythrocyte Health Index has important clinical implications for SCD management and could be used by providers when making treatment decisions. Further research is warranted to evaluate the clinical utility and applicability of the Sickle Erythrocyte Health Index in diverse patient populations.

Cellular behavior and extracellular matrix turnover in bovine annulus fibrosus cells under hydrostatic pressure and deviatoric strain.

Intervertebral disc herniation is a common spinal disorder that is often treated with discectomy when conservative measures fail. To devise therapeutic strategies for tears in the annulus fibrosus (AF), the regenerative capability of AF cells under spinal loading needs to be addressed. We hypothesized that the compressive loading associated with deformation in AF cells reduces synthetic and degradative activities in extracellular matrix and cell proliferation. We evaluated expression of key matrix molecules and cell proliferation by RT-PCR and immunohistochemistry by inner and outer bovine AF cells incubated under hydrostatic pressure (HP), arc-bending strain (Strain), and combined HP and Strain (HP/Strain) mimicking spinal loading. Inner AF cells showed significantly increased levels of aggrecan core protein, chondroitin sulfate N-acetylgalactosaminyltransferase-1, and tissue inhibitor of metalloproteinases-2 by 6 days under HP (p < 0.05), with a tendency toward increased matrix metalloproteinase-13. Outer AF cells demonstrated a significant decline in collagen type-2 under Strain and HP/Strain (p < 0.05) and a tendency toward suppression of collagen type-1 and elastin expression compared to HP and unloaded control. On the other hand, proliferating cell nucleus antigen increased significantly under Strain and HP/Strain in inner AF and declined under unloaded and HP in outer AF (p < 0.05). Immunohistology findings supported reductions in gene expressions of matrix molecules. Thus, changes in HP/Strain in AF appear to diminish synthetic and degradative activities while increasing cell proliferation. To promote regeneration, continuous overloading should be avoided, as it converts the synthetic activity to a state in which tissue repair is limited.