Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 225
Filter
1.
Article in English | MEDLINE | ID: mdl-38530331

ABSTRACT

The patient is a 15-year-old girl who was diagnosed with hypertrophic cardiomyopathy and has been symptomatic due to severe left ventricular outflow tract obstruction. Combined transaortic and transapical left ventricular septal myectomy was performed to relieve the left ventricular outflow tract obstruction and address both subaortic and midventricular gradients.


Subject(s)
Cardiomyopathy, Hypertrophic , Ventricular Outflow Obstruction, Left , Female , Humans , Child , Adolescent , Cardiomyopathy, Hypertrophic/surgery , Coronary Artery Bypass
2.
Cardiol Young ; : 1-3, 2024 Feb 27.
Article in English | MEDLINE | ID: mdl-38410047

ABSTRACT

BACKGROUND: Tetralogy of Fallot is the most prevalent cyanotic CHD. With the advent of advanced surgical methods, the majority of tetralogy of Fallot patients reach adulthood. However, many need re-intervention for the residual anomalies including residual right ventricular outflow obstruction, pulmonary regurgitation, residual ventricular septal defects, and progressive aortic dilatation. Aortic dilation could lead to aortic regurgitation or dissection requiring surgical correction. In the current study, we aimed to determine the prevalence and outcomes of aortic root dilatation in adults with repaired tetralogy of Fallot in our tertiary care centre. METHODS: In this retrospective study, 730 consecutive patients with history of repaired tetralogy of Fallot were included. Aortic diameter at the level of annulus, the sinus of Valsalva, sinotubular junction, and the ascending aorta as measured by echocardiography were evaluated. Prevalence of outcomes necessitating re-intervention including aortic regurgitation and dissection were recorded. RESULTS: The mean size of annulus, sinus of Valsalva, sinotubular-junction, and ascending aorta in the latest available echocardiography of patients were 2.4+/-0.4 cm, 3.3+/-0.5 cm, 2.9+/-0.5cm, and 3.2+/-0.5cm, respectively. Prevalence of dilatation of sinus of Valsalva, dilation of Ascending aorta, sinotubular-junction, and aortic annulus was 28.7%, 21%, 8.3%, and 1 %, respectively. Five patients had severe aortic regurgitation (0.6%) and underwent surgical repair. One of these patients presented with acute aortic dissection. CONCLUSION: Aortic dilation is common in tetralogy of Fallot but prevalence of redo surgery for aortic dilation, regurgitation, and adverse events including acute dissection is low.

3.
J Matern Fetal Neonatal Med ; 37(1): 2305680, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38253519

ABSTRACT

OBJECTIVES: To assess the association between allostatic load in early pregnancy and sleep-disordered breathing (SDB) during pregnancy. METHODS: High allostatic load in the first trimester was defined as ≥ 4 of 12 biomarkers (systolic blood pressure, diastolic blood pressure, body mass index, cholesterol, low-density lipoprotein, high-density lipoprotein, high sensitivity C-reactive protein, triglycerides, insulin, glucose, creatinine, and albumin) in the unfavorable quartile. SDB was objectively measured using the Embletta-Gold device and operationalized as "SDB ever" in early (6-15 weeks) or mid-pregnancy (22-31 weeks); SDB at each time point was analyzed as secondary outcomes. Multivariable logistic regression was used to test the association between high allostatic load and SDB, adjusted for confounders. Moderation and sensitivity analyses were conducted to assess the role of allostatic load in racial disparities of SDB and obesity affected the relationship between allostatic load and SDB. RESULTS: High allostatic load was present in 35.0% of the nuMoM2b cohort. The prevalence of SDB ever occurred among 8.3% during pregnancy. After adjustment, allostatic load remained significantly associated with SDB ever (aOR= 5.3; 3.6-7.9), in early-pregnancy (aOR= 7.0; 3.8-12.8), and in mid-pregnancy (aOR= 5.8; 3.7-9.1). The association between allostatic load and SDB was not significantly different for people with and without obesity. After excluding BMI from the allostatic load score, the association decreased in magnitude (aOR= 2.6; 1.8-3.9). CONCLUSION: The association between allostatic load and SDB was independent of confounders including BMI. The complex and likely bidirectional relationship between chronic stress and SDB deserves further study in reducing SDB.


Subject(s)
Allostasis , Female , Pregnancy , Humans , Body Mass Index , C-Reactive Protein , Creatinine , Obesity
4.
Nat Commun ; 14(1): 8275, 2023 Dec 13.
Article in English | MEDLINE | ID: mdl-38092784

ABSTRACT

In vascular plants, the epidermal surfaces of leaves and flower petals often display cells with wavy geometries forming intricate jigsaw puzzle patterns. The prevalence and diversity of these complex epidermal patterns, originating from simple polyhedral progenitor cells, suggest adaptive significance. However, despite multiple efforts to explain the evolutionary drivers behind these geometrical features, compelling validation remains elusive. Employing a multidisciplinary approach that integrates microscopic and macroscopic fracture experiments with computational fracture mechanics, we demonstrate that wavy epidermal cells toughen the plants' protective skin. Through a multi-scale framework, we demonstrate that this energy-efficient patterning mechanism is universally applicable for toughening biological and synthetic materials. Our findings reveal a tunable structural-mechanical strategy employed in the microscale design of plants to protect them from deleterious surface fissures while facilitating and strategically directing beneficial ones. These findings hold implications for targeted plant breeding aimed at enhancing resilience in fluctuating environmental conditions. From an engineering perspective, our work highlights the sophisticated design principles the plant kingdom offers to inspire metamaterials.


Subject(s)
Fractures, Bone , Plant Breeding , Plant Leaves , Flowers , Plants
5.
Trends Plant Sci ; 28(10): 1095-1097, 2023 10.
Article in English | MEDLINE | ID: mdl-37541814

ABSTRACT

Large language models (LLMs) will benefit science by accelerating task performance. We explored whether answers generated by ChatGPT (generative pretrained transformer) to questions of biology are sufficiently diverse. 'Plant awareness' in ChatGPT answers was found to be highly variable, illustrating the importance of scientists being involved in validating the data and methods used to train artificial intelligence (AI) models.


Subject(s)
Artificial Intelligence , Language , Blindness
6.
BJOG ; 130(10): 1197-1206, 2023 09.
Article in English | MEDLINE | ID: mdl-37069728

ABSTRACT

OBJECTIVE: To assess the relationship between allostatic load, a measure of cumulative chronic stress in early pregnancy and cardiovascular disease risk, 2-7 years postpartum, and pathways contributing to racial disparities in cardiovascular disease risk. DESIGN: Secondary analysis of a prospective cohort study. SETTING MULTICENTER POPULATION: Pregnant women. METHODS: Our primary exposure was high allostatic load in the first trimester, defined as at least 4 of 12 biomarkers (systolic blood pressure, diastolic blood pressure, body mass index, cholesterol, low-density lipoprotein, high-density lipoprotein, high-sensitivity C-reactive protein, triglycerides, insulin, glucose, creatinine and albumin) in the unfavourable quartile. Logistic regression was used to test the association between high allostatic load and main outcome adjusted for confounders: time from index pregnancy and follow up, age, education, smoking, gravidity, bleeding in the first trimester, index adverse pregnancy outcomes, and health insurance. Each main outcome component and allostatic load were analysed secondarily. Mediation and moderation analyses assessed the role of high allostatic load in racial disparities of cardiovascular disease risk. MAIN OUTCOME MEASURE: Incident cardiovascular disease risk: hypertension, or metabolic disorders. RESULTS: Cardiovascular disease risk was identified in 1462/4022 individuals (hypertension: 36.6%, metabolic disorder: 15.4%). After adjustment, allostatic load was associated with cardiovascular disease risk (adjusted odds ratio [aOR] 2.0, 95% CI 1.8-2.3), hypertension (aOR 2.1, 95% CI 1.8-2.4) and metabolic disorder (aOR 1.7, 95% CI 1.5-2.1). Allostatic load was a partial mediator between race and cardiovascular disease risk. Race did not significantly moderate this relationship. CONCLUSIONS: High allostatic load during pregnancy is associated with cardiovascular disease risk. The relationships between stress, subsequent cardiovascular risk and race warrant further study.


Subject(s)
Allostasis , Cardiovascular Diseases , Hypertension , Pregnancy , Humans , Female , Cohort Studies , Allostasis/physiology , Cardiovascular Diseases/etiology , Prospective Studies , Pregnancy Outcome , Lipoproteins, HDL
7.
Methods Mol Biol ; 2604: 25-42, 2023.
Article in English | MEDLINE | ID: mdl-36773223

ABSTRACT

The plant cytoskeleton is instrumental in cellular processes such as cell growth, differentiation, and immune response. Microtubules, in particular, play a crucial role in morphogenesis by governing the deposition of plant cell wall polysaccharides and, in consequence, the cell wall mechanics and cell shape. Scrutinizing the microtubule dynamics is therefore integral to understanding the spatiotemporal regulation of cellular activities. In this chapter, we outline steps to acquire 3D images of microtubules in epidermal pavement cells of Arabidopsis thaliana cotyledons using a confocal microscope. We introduce the steps to assess the microtubule distribution and organization using image processing software Bitplane Imaris and ImageJ. We also demonstrate how the interpretation of image material can be facilitated by post-processing with general-purpose image enhancement software using methods trained by artificial intelligence-based algorithms.


Subject(s)
Arabidopsis , Artificial Intelligence , Imaging, Three-Dimensional , Microtubules , Cytoskeleton
8.
Obstet Gynecol ; 140(6): 974-982, 2022 12 01.
Article in English | MEDLINE | ID: mdl-36357956

ABSTRACT

OBJECTIVE: To assess the association between allostatic load, as an estimate of chronic stress, and adverse pregnancy outcomes. METHODS: This was a secondary analysis of nuMoM2b (Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be), a prospective observational cohort study. Our primary exposure was dichotomous high allostatic load in the first trimester, defined as 4 or more of 12 biomarkers in the "worst" quartile. The primary outcome was a composite adverse pregnancy outcome: hypertensive disorders of pregnancy (HDP), preterm birth, small for gestational age (SGA), and stillbirth. Secondary outcomes included components of the composite. Multivariable logistic regression was used to test the association between high allostatic load and adverse pregnancy outcomes, adjusted for potential confounders. Mediation and moderation analyses were conducted to assess the role of allostatic load along the causal pathway between racial disparities and adverse pregnancy outcomes. RESULTS: Among 4,266 individuals, 34.7% had a high allostatic load. Composite adverse pregnancy outcome occurred in 1,171 (27.5%): 14.0% HDP, 8.6% preterm birth (48.0% spontaneous and 52.2% indicated), 11.0% SGA, and 0.3% stillbirth. After adjustment for maternal age, gravidity, smoking, bleeding in the first trimester, and health insurance, high allostatic load was significantly associated with a composite adverse pregnancy outcome (adjusted odds ratio [aOR] 1.5, 95% CI 1.3, 1.7) and HDP (aOR 2.5, 95% CI 2.0-2.9), but not preterm birth or SGA. High allostatic load partially mediated the association between self-reported race and adverse pregnancy outcomes. The association between allostatic load and HDP differed by self-reported race, but not for a composite adverse pregnancy outcome, preterm birth, or SGA. CONCLUSION: High allostatic load in the first trimester is associated with adverse pregnancy outcomes, particularly HDP. Allostatic load was a partial mediator between race and adverse pregnancy outcomes. The association between allostatic load and HDP differed by self-reported race.


Subject(s)
Allostasis , Infant, Newborn, Diseases , Pre-Eclampsia , Premature Birth , Infant, Newborn , Female , Pregnancy , Humans , Pregnancy Outcome , Stillbirth , Prospective Studies , Premature Birth/epidemiology , Fetal Growth Retardation
9.
Clin Rehabil ; 36(11): 1424-1449, 2022 Nov.
Article in English | MEDLINE | ID: mdl-35787015

ABSTRACT

OBJECTIVE: To conduct a systematic review of the effectiveness of facial exercise therapy for facial palsy patients, updating an earlier broader Cochrane review; and to provide evidence to inform the development of telerehabilitation for these patients. DATA SOURCES: MEDLINE, EMBASE, CINAHL, Cochrane Library, PEDro and AMED for relevant studies published between 01 January 2011 and 30 September 2020. METHODS: Predetermined inclusion/exclusion criteria were utilised to shortlist abstracts. Two reviewers independently appraised articles, systematically extracted data and assessed the quality of individual studies and reviews (using GRADE and AMSTAR-2, respectively). Thematic analysis used for evidence synthesis; no quantitative meta-analysis conducted. The review was registered with PROSPERO (CRD42017073067). RESULTS: Seven new randomised controlled trials, nine observational studies, and three quasi-experimental or pilot studies were identified (n = 854 participants). 75% utilised validated measures to record changes in facial function and/or patient-rated outcomes. High-quality trials (4/7) all reported positive impacts; as did observational studies rated as high/moderate quality (3/9). The benefit of therapy at different time points post-onset and for cases of varying clinical severity is discussed. Differences in study design prevented data pooling to strengthen estimates of therapy effects. Six new review articles identified were all rated critically low quality. CONCLUSION: The findings of this targeted review reinforce those of the earlier more general Cochrane review. New research studies strengthen previous conclusions about the benefits of facial exercise therapy early in recovery and add to evidence of the value in chronic cases. Further standardisation of study design/outcome measures and evaluation of cost-effectiveness are recommended.


Subject(s)
Bell Palsy , Facial Paralysis , Bell Palsy/drug therapy , Exercise Therapy , Facial Nerve , Facial Paralysis/therapy , Humans , Physical Therapy Modalities
10.
Sci Rep ; 12(1): 10463, 2022 Jun 21.
Article in English | MEDLINE | ID: mdl-35729199

ABSTRACT

Orthogonal Frequency-Division Multiplexing with Random multiple access (OFDRMA) is discussed for uplink communications, whereby several active users send information towards a single base-station (BS), while all other users are dormant. Originally, uplink communication methods included sharing the frequency resources among the active users in an orthogonal fashion, i.e., a central unit is required to dynamically allocate the resources. More recently, non-orthogonal methods have arisen, meaning that several active users share the same frequency bins, but they still do require a central unit to dynamically allocate the resources in a uniform (as possible) manner over the available bandwidth. The task and overhead required for managing the frequency allocations among the users can be quite cumbersome. In OFDRMA, the frequency allocations for any user are independent of the frequency allocations for the other users, and independent of which of the other users are currently active. Rather, OFDRMA relies on random, yet predetermined, allocation of frequency bins for each user, known only to that user and the BS. A multi-user detection approach is presented based on a graphical representation of the system. It is shown to provide robustness against the forced randomness of the scheme. Capacity of OFDRMA and its optimization are analyzed and provided in detail. Simulation results are provided for demonstrating the performance attainable with OFDRMA and the proposed detection scheme. Both the capacity and the simulations are compared with modern multi-user multiple-input multiple-output (MU-MIMO) schemes.

11.
Curr Biol ; 31(10): R681-R695, 2021 05 24.
Article in English | MEDLINE | ID: mdl-34033798

ABSTRACT

The plant cell wall is an extracellular matrix that envelopes cells, gives them structure and shape, constitutes the interface with symbionts, and defends plants against external biotic and abiotic stress factors. The assembly of this matrix is regulated and mediated by the cytoskeleton. Cytoskeletal elements define where new cell wall material is added and how fibrillar macromolecules are oriented in the wall. Inversely, the cytoskeleton is also key in the perception of mechanical cues generated by structural changes in the cell wall as well as the mediation of intracellular responses. We review the delivery processes of the cell wall precursors that are required for the cell wall assembly process and the structural continuity between the inside and the outside of the cell. We provide an overview of the different morphogenetic processes for which cell wall assembly is a crucial element and elaborate on relevant feedback mechanisms.


Subject(s)
Cell Wall/metabolism , Cytoskeleton/metabolism , Plant Cells/metabolism , Plants/metabolism
12.
Am J Orthod Dentofacial Orthop ; 160(2): 215-220.e2, 2021 Aug.
Article in English | MEDLINE | ID: mdl-32863087

ABSTRACT

INTRODUCTION: As a powerful numerical approximation tool, finite element analysis (FEA) has been widely used to predict stress and strain distributions in facial bones generated by orthodontic appliances. Previous FEA models were constructed on the basis of a linear elastic phase of the bone response (eg, elastic bone strains to loading). However, what is more useful for clinical understanding would be predicting long-term strains and displacements of bone-segments responding to loading, yet tissue responses are (1) not promptly observable and (2) hard to predict in nature. METHODS: Viscoelastic property of the mandibular bone was incorporated into FEA models to visualize long-term, time-dependent stress and strain patterns in the mandible after being exposed to orthopedic stress. A mandible under loading by a Herbst appliance was modeled, and outcomes of the constructed elastic and viscoelastic models were compared. RESULTS: Patterns and magnitudes of the displacement throughout the mandible predicted by the viscoelastic model were exhibited in accordance with previous clinical outcomes of Herbst appliance therapy. The elastic models exhibited similar displacement patterns; however, the magnitude of the displacements in the models was invariably small (approximately 1 per 100) compared with those outputs of corresponding viscoelastic models. The corresponding maximum stress level in our viscoelastic mandible subjected to the Herbst appliance with the same loading was considerably low and relaxed in various regions when compared with the elastic model. CONCLUSIONS: We suggest that a viscoelastic model of the mandible mimics our general prediction of orthopedic treatment outcomes better than those by elastic models.


Subject(s)
Orthodontic Appliances, Functional , Finite Element Analysis , Humans , Mandible , Orthodontic Appliances
13.
Cell Rep Med ; 1(2)2020 05 19.
Article in English | MEDLINE | ID: mdl-32864636

ABSTRACT

Development of effective prevention and treatment strategies for pre-eclampsia is limited by the lack of accurate methods for identification of at-risk pregnancies. We performed small RNA sequencing (RNA-seq) of maternal serum extracellular RNAs (exRNAs) to discover and verify microRNAs (miRNAs) differentially expressed in patients who later developed pre-eclampsia. Sera collected from 73 pre-eclampsia cases and 139 controls between 17 and 28 weeks gestational age (GA), divided into separate discovery and verification cohorts, are analyzed by small RNA-seq. Discovery and verification of univariate and bivariate miRNA biomarkers reveal that bivariate biomarkers verify at a markedly higher rate than univariate biomarkers. The majority of verified biomarkers contain miR-155-5p, which has been reported to mediate the pre-eclampsia-associated repression of endothelial nitric oxide synthase (eNOS) by tumor necrosis factor alpha (TNF-α). Deconvolution analysis reveals that several verified miRNA biomarkers come from the placenta and are likely carried by placenta-specific extracellular vesicles.


Subject(s)
Extracellular Vesicles/metabolism , MicroRNAs/blood , Pre-Eclampsia/diagnosis , Adult , Asymptomatic Diseases , Biomarkers/blood , Case-Control Studies , Extracellular Vesicles/genetics , Female , Gestational Age , Humans , Maternal Serum Screening Tests/methods , Maternal Serum Screening Tests/trends , MicroRNAs/metabolism , Pre-Eclampsia/blood , Pregnancy , Prognosis , Young Adult
14.
Methods Cell Biol ; 160: 327-348, 2020.
Article in English | MEDLINE | ID: mdl-32896326

ABSTRACT

Tensile testing is widely used to evaluate the mechanical properties of biological materials including soft primary plant tissues. Commercially available platforms for tensile testing are often expensive and limited in customizability. In this chapter, we provide a guide for the assembly and use of a simple and low-cost micromechanical testing apparatus suitable for research and educational purposes. The build of the setup is presented with scalability and universality in mind and is based on a do-it-yourself mind frame towards mechanical tests on plant organs and tissues. We discuss hardware and software requirements with practical details on required components, device calibration and a script to run the device. Further, we provide an example in which the device was used for the uniaxial tensile test of onion epidermis.


Subject(s)
Botany/instrumentation , Onions/physiology , Organ Specificity , Biomechanical Phenomena , Calibration , Plant Epidermis/physiology , Principal Component Analysis , Software , Stress, Mechanical , Tensile Strength , User-Computer Interface
15.
Am J Cardiol ; 130: 78-84, 2020 09 01.
Article in English | MEDLINE | ID: mdl-32674809

ABSTRACT

Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality globally. The goals of this study were to describe common causes of OHCA in an urban US medical center, identify predictive factors for survival, and to assess whether neurological status upon return of spontaneous circulation might be predictive of outcomes: 124 consecutive patients aged 18 years and older with OHCA admitted at Advocate Illinois Masonic Medical Center were studied. All patients resuscitated in the field with return of spontaneous circulation then transferred to the emergency department were included. The Glasgow Coma Score (GCS) was evaluated immediately on hospital arrival. In the total group, 34% (42 of 124) were discharged alive. In patients with coronary artery disease (CAD), 51% (20 of 39) were discharged alive versus 26% (22 of 85) of non-CAD patients (p <0.01). Initial GCS ≥ 9 was highly predictive of survival: 94% (34 of 36) of patients with GCS ≥ 9 survived versus 9% (8 of 88) with GCS ≤ 8 (p <0.0001). Defibrillation in the field was predictive of survival (chi-square = 7.81, p = 0.005). In the CAD group, all 16 patients with GCS ≥ 9 on presentation to the Emergency Department survived whereas all 13 with GCS ≤ 5 died (both p <0.0001). In the non-CAD group, 18 of 20 patients with GCS ≥ 9 survived, whereas only 2 of 52 with GCS ≤ 5 survived (both p <0.0001). Multivariate analysis by logistic regression showed that the strongest predictor of survival in the non-CAD subgroup was GCS (OR 0.27, CI 0.19 to 0.55, p <0.001). In conclusion, the etiology of the OHCA, immediate neurologic status, and defibrillation in the field (suggesting presenting arrhythmia) were predictive of survival. Immediate neurological recovery (GCS ≥ 9) regardless of etiology was a strong predictor of survival to discharge. Additional predictive factors depend on the etiology of the OHCA event. These data suggest that these straightforward factors can be helpful in predicting outcome in patients resuscitated after OHCA.


Subject(s)
Hospitalization , Out-of-Hospital Cardiac Arrest/mortality , Out-of-Hospital Cardiac Arrest/therapy , Resuscitation , Adult , Coronary Artery Disease/complications , Hospitals, Urban , Humans , Out-of-Hospital Cardiac Arrest/etiology , Survival Rate , United States
16.
Plant Physiol ; 181(1): 127-141, 2019 09.
Article in English | MEDLINE | ID: mdl-31363005

ABSTRACT

Simple plant cell morphologies, such as cylindrical shoot cells, are determined by the extensibility pattern of the primary cell wall, which is thought to be largely dominated by cellulose microfibrils, but the mechanism leading to more complex shapes, such as the interdigitated patterns in the epidermis of many eudicotyledon leaves, is much less well understood. Details about the manner in which cell wall polymers at the periclinal wall regulate the morphogenetic process in epidermal pavement cells and mechanistic information about the initial steps leading to the characteristic undulations in the cell borders are elusive. Here, we used genetics and recently developed cell mechanical and imaging methods to study the impact of the spatio-temporal dynamics of cellulose and homogalacturonan pectin distribution during lobe formation in the epidermal pavement cells of Arabidopsis (Arabidopsis thaliana) cotyledons. We show that nonuniform distribution of cellulose microfibrils and demethylated pectin coincides with spatial differences in cell wall stiffness but may intervene at different developmental stages. We also show that lobe period can be reduced when demethyl-esterification of pectins increases under conditions of reduced cellulose crystallinity. Our data suggest that lobe initiation involves a modulation of cell wall stiffness through local enrichment in demethylated pectin, whereas subsequent increase in lobe amplitude is mediated by the stress-induced deposition of aligned cellulose microfibrils. Our results reveal a key role of noncellulosic polymers in the biomechanical regulation of cell morphogenesis.


Subject(s)
Arabidopsis/metabolism , Cellulose/metabolism , Pectins/metabolism , Arabidopsis/growth & development , Biomechanical Phenomena , Cell Wall/metabolism , Cotyledon/growth & development , Cotyledon/metabolism , Esterification , Plant Leaves/growth & development , Plant Leaves/metabolism
17.
Cell Rep ; 28(5): 1237-1250.e6, 2019 07 30.
Article in English | MEDLINE | ID: mdl-31365867

ABSTRACT

Pavement cells form wavy interlocking patterns in the leaf epidermis of many plants. We use computational mechanics to simulate the morphogenetic process based on microtubule organization and cell wall chemistry. Based on the in silico simulations and experimental evidence, we suggest that a multistep process underlies the morphogenesis of pavement cells. The in silico model predicts alternatingly located, feedback-augmented mechanical heterogeneity of the periclinal and anticlinal walls. It suggests that the emergence of waves is created by a stiffening of the emerging indented sides, an effect that matches cellulose and de-esterified pectin patterns in the cell wall. Further, conceptual evidence for mechanical buckling of the cell walls is provided, a mechanism that has the potential to initiate wavy patterns de novo and may precede chemical and geometrical symmetry breaking.


Subject(s)
Arabidopsis/metabolism , Computer Simulation , Models, Biological , Plant Epidermis/metabolism , Plant Leaves/metabolism , Stress, Mechanical , Arabidopsis/cytology , Plant Epidermis/cytology , Plant Leaves/cytology
18.
J Exp Bot ; 70(14): 3615-3648, 2019 07 23.
Article in English | MEDLINE | ID: mdl-31301141

ABSTRACT

The primary plant cell wall is a dynamically regulated composite material of multiple biopolymers that forms a scaffold enclosing the plant cells. The mechanochemical make-up of this polymer network regulates growth, morphogenesis, and stability at the cell and tissue scales. To understand the dynamics of cell wall mechanics, and how it correlates with cellular activities, several experimental frameworks have been deployed in recent years to quantify the mechanical properties of plant cells and tissues. Here we critically review the application of biomechanical tool sets pertinent to plant cell mechanics and outline some of their findings, relevance, and limitations. We also discuss methods that are less explored but hold great potential for the field, including multiscale in silico mechanical modeling that will enable a unified understanding of the mechanical behavior across the scales. Our overview reveals significant differences between the results of different mechanical testing techniques on plant material. Specifically, indentation techniques seem to consistently report lower values compared with tensile tests. Such differences may in part be due to inherent differences among the technical approaches and consequently the wall properties that they measure, and partly due to differences between experimental conditions.


Subject(s)
Biophysics/methods , Cell Wall/chemistry , Plant Cells/chemistry , Biomechanical Phenomena , Plant Development
19.
Dev Cell ; 50(1): 117-125.e2, 2019 07 01.
Article in English | MEDLINE | ID: mdl-31265810

ABSTRACT

Morphogenesis of wavy epidermal pavement cells in plants has fascinated researchers for decades. A mechanical mechanism had been proposed in which the anticlinal cell walls, forming the in-plane cell borders, feature contiguous stiff and soft zones that generate waves upon stretching. We replicated this model as designed and also expanded on it to test its validity for three-dimensional (3D) cell geometry. Our results suggest that both the assumptions going into and the predictions arising from this hypothesis do not stand closer scrutiny and may misguide experimentalists. Unlike what the published data seem to suggest, we observed that only waves of negligible magnitude can be formed by this anticlinal stretch model and that these are virtually eliminated when full 3D geometry of the cell is considered. Further, the model produces cell wall stresses that do not match the experimental evidence.


Subject(s)
Cell Wall , Plant Cells , Epidermal Cells , Morphogenesis
20.
Front Pharmacol ; 9: 678, 2018.
Article in English | MEDLINE | ID: mdl-30093859

ABSTRACT

Background: There is currently a need for high quality evaluations of new mobile health, telehealth, smart pump and monitoring technologies undertaken in a pharmacy-related setting. We aim to evaluate the use of these monitoring technologies performed in this setting. Methods: A systematic searching of English articles that examined the quality and the design of technologies conducted in pharmacy-related facilities was performed using the following databases: MEDLINE and Cumulative index to Nursing and Allied Health Literature (CINAHL) to identify original studies examining the quality and the design of technologies and published in peer-reviewed journals. Extraction of articles and quality assessment of included articles were performed independently by two authors. Quality scores over 75% are classed as being acceptable using a "relatively conservative" quality benchmark. Scores over 55% are included using a "relatively liberal" cut-off point. Results: Screening resulted in the selection of 40 formal evaluations. A substantial number of studies (32, 80.00%) were performed in the United States, quantitative in approach (33, 82.50%) and retrospective cohort (24, 60.00%) in study design. The most common pharmacy-related settings were: 22 primary care (55.00%); 10 hospital pharmacy (25.00%); 7 community pharmacy (17.50%); one primary care and hospital pharmacy (2.50%). The majority of the evaluations (33, 82.50%) reported clinical outcomes, six (15.00%) measured clinical and economic outcomes, and one (2.50%) economic only. Twelve (30.00%) quantitative studies and no qualitative study met objective criteria for "relatively conservative" quality. Using a lower "relatively liberal" benchmark, 27 quantitative (81.82%) and four qualitative (57.41%) studies met the lower quality criterion. Conclusion: Worldwide, few evaluations of mobile health, telehealth, smart pump and monitoring technologies in pharmacy-related setting have been published.Their quality is often below the standard necessary for inclusion in a systematic review mainly due to inadequate study design.

SELECTION OF CITATIONS
SEARCH DETAIL
...