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1.
Sex Transm Dis ; 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38709026

RESUMO

ABSTRACT: We evaluated the proportion of patients with trichomoniasis and chlamydial infections who received recommended versus non-recommended antibiotic therapy after the updated 2021 Sexually Transmitted Infections Guideline. Of 712 patients, 473 (66%) received recommended therapy. Receipt of emergency department care was independently associated with recommended therapy (adjOR, 2.1; 95% CI 1.5-2.9).

2.
Liver Transpl ; 26(1): 100-112, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31742878

RESUMO

Biliary complications (strictures and leaks) represent major limitations in living donor liver transplantation. Mesenchymal stem cells (MSCs) are a promising modality to prevent biliary complications because of immunosuppressive and angiogenic properties. Our goal was to evaluate the safety of adipose-derived MSC delivery to biliary anastomoses in a porcine model. Secondary objectives were defining the optimal method of delivery (intraluminal versus extraluminal) and to investigate MSC engraftment, angiogenesis, and fibrosis. Pigs were divided into 3 groups. Animals underwent adipose collection, MSC isolation, and expansion. Two weeks later, animals underwent bile duct transection, reanastomosis, and stent insertion. Group 1 received plastic stents wrapped in unseeded Vicryl mesh. Group 2 received stents wrapped in MSC-seeded mesh. Group 3 received unwrapped stents with the anastomosis immersed in an MSC suspension. Animals were killed 1 month after stent insertion when cholangiograms and biliary tissue were obtained. Serum was collected for liver biochemistries. Tissue was used for hematoxylin-eosin and trichrome staining and immunohistochemistry for MSC markers (CD44 and CD34) and for a marker of neoangiogenesis (CD31). There were no intraoperative complications. One pig died on postoperative day 3 due to acute cholangitis. All others recovered without complications. Cholangiography demonstrated no biliary leaks and minimal luminal narrowing. Surviving animals exhibited no symptoms, abnormal liver biochemistries, or clinically significant biliary stricturing. Group 3 showed significantly greater CD44 and CD34 staining, indicating MSC engraftment. Fibrosis was reduced at the anastomotic site in group 3 based on trichrome stain. CD31 staining of group 3 was more pronounced, supporting enhanced neoangiogenesis. In conclusion, adipose-derived MSCs were safely applied to biliary anastomoses. MSCs were locally engrafted within the bile duct and may have beneficial effects in terms of fibrosis and angiogenesis.


Assuntos
Transplante de Fígado , Células-Tronco Mesenquimais , Animais , Ductos Biliares/cirurgia , Humanos , Imersão , Doadores Vivos , Complicações Pós-Operatórias , Stents , Suínos
3.
Pharm Res ; 35(8): 155, 2018 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-29869098

RESUMO

PURPOSE: Cell migration/invasion assays are widely used in commercial drug discovery screening. 3D printing enables the creation of diverse geometric restrictive barrier designs for use in cell motility studies, permitting on-demand assays. Here, the utility of 3D printed cell exclusion spacers (CES) was validated as a cell motility assay. METHODS: A novel CES fit was fabricated using 3D printing and customized to the size and contour of 12 cell culture plates including 6 well plates of basal human brain vascular endothelial (D3) cell migration cells compared with 6 well plates with D3 cells challenged with 1uM cytochalasin D (Cyto-D), an F-actin anti-motility drug. Control and Cyto-D treated cells were monitored over 3 days under optical microscopy. RESULTS: Day 3 cell migration distance for untreated D3 cells was 1515.943µm ± 10.346µm compared to 356.909µm ± 38.562µm for the Cyt-D treated D3 cells (p < 0.0001). By day 3, untreated D3 cells reached confluency and completely filled the original voided spacer regions, while the Cyt-D treated D3 cells remained significantly less motile. CONCLUSIONS: Cell migration distances were significantly reduced by Cyto-D, supporting the use of 3D printing for cell exclusion assays. 3D printed CES have great potential for studying cell motility, migration/invasion, and complex multi-cell interactions.


Assuntos
Técnicas de Cultura de Células/instrumentação , Ensaios de Migração Celular/instrumentação , Células Endoteliais/citologia , Impressão Tridimensional , Encéfalo/citologia , Linhagem Celular , Movimento Celular , Desenho de Equipamento , Humanos , Técnicas de Cultura de Tecidos/instrumentação
4.
J Oral Maxillofac Surg ; 76(7): 1562.e1-1562.e5, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29679585

RESUMO

PURPOSE: After cleft lip and palate surgical procedures, patients often need nostril supports to help the reconstructed nostrils retain their shape during healing. Many postoperative nasal stents use a one-size-fits-all approach, in which a standard rubber tube retainer is trimmed and used to support the healing nares. The purpose of this study was to examine photogrammetry and 3-dimensional (3D) printing as a fabrication tool for postoperative patient-specific nasal supports that can be loaded with bioactive agents for localized delivery. MATERIALS AND METHODS: A "normal" right nostril injection mold was prepared from a left-sided unilateral cleft defect, and the negative-space impression was modeled using a series of photographs taken at different rotation angles with a commercial mobile phone camera. These images were "stitched" together using photogrammetry software, and the computer-generated models were reflected, joined, and digitally sculpted to generate hollow bilateral supports. Three-dimensional prints were coated with polyvinylpyrrolidone-penicillin and validated for their ability to inhibit Escherichia coli using human blood agar diffusion assays. RESULTS: The results showed that our approach had a high level of contour replication and the antibiotic coating was able to inhibit bacterial growth with a mean zone of inhibition of 15.15 ± 0.99 mm (n = 9) (P < .0001) in disc diffusion assays. CONCLUSIONS: Consumer-grade 3D printing displays potential as a fabrication method for postoperative cleft bilateral nasal supports and may support the surgically reconstructed internal contours. The results of this study suggest that such types of bioactive 3D prints may have potential applications in personalized drug-delivery systems and medical devices.


Assuntos
Fenda Labial/cirurgia , Fissura Palatina/cirurgia , Stents Farmacológicos , Rinoplastia/métodos , Antibacterianos/administração & dosagem , Escherichia coli/efeitos dos fármacos , Humanos , Modelos Anatômicos , Penicilinas/administração & dosagem , Excipientes Farmacêuticos/administração & dosagem , Fotogrametria , Povidona/administração & dosagem , Impressão Tridimensional , Desenho de Prótese
5.
N Engl J Med ; 380(20): 1981-1982, 2019 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-31091396

Assuntos
Organoides , Humanos
6.
Nanotechnology ; 28(36): 365704, 2017 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-28604369

RESUMO

Despite the strong interest in optoelectronic devices working in the deep ultraviolet range, no suitable low cost, large-area, high-quality AlN substrates have been available up to now. The aim of this work is the selective area growth of AlN nanocolumns by plasma assisted molecular beam epitaxy on polar (0001) and semi-polar (11-22) GaN/sapphire templates. The resulting AlN nanocolumns are vertically oriented with semi-polar {1-103} top facets when grown on (0001) GaN/sapphire, or oriented at 58° from the template normal and exposing {1-100} non-polar top facets when growing on (11-22) GaN/sapphire, in both cases reaching filling factors ≥80%. In these kinds of arrays each nanostructure could function as a building block for an individual nano-device or, due to the large filling factor values, the overall array top surfaces could be seen as a quasi (semi-polar or non-polar) AlN pseudo-template.

7.
Inj Prev ; 27(6): 592-593, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-33402354
8.
Nano Lett ; 15(8): 5105-9, 2015 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-26225541

RESUMO

Selective area growth has been applied to fabricate a homogeneous array of GaN nanocolumns (NC) with high crystal quality. The structural and optical properties of single NCs have been investigated at the nanometer-scale by transmission electron microscopy (TEM) and highly spatially resolved cathodoluminescence (CL) spectroscopy performed in a scanning transmission electron microscope (STEM) at liquid helium temperatures. TEM cross-section analysis reveals excellent structural properties of the GaN NCs. Sporadically, isolated basal plane stacking faults (BSF) can be found resulting in a remarkably low BSF density in the almost entire NC ensemble. Both, defect-free NCs and NCs with few BSFs have been investigated. The low defect density within the NCs allows the characterization of individual BSFs, which is of high interest for studying their optical properties. Direct nanometer-scale correlation of the CL and STEM data clearly exhibits a spatial correlation of the emission at 360.6 nm (3.438 eV) with the location of basal plane stacking faults of type I1.

9.
Lifetime Data Anal ; 22(3): 405-28, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26307336

RESUMO

Degradation tests are especially difficult to conduct for items with high reliability. Test costs, caused mainly by prolonged item duration and item destruction costs, establish the necessity of sequential degradation test designs. We propose a methodology that sequentially selects the optimal observation times to measure the degradation, using a convenient rule that maximizes the inference precision and minimizes test costs. In particular our objective is to estimate a quantile of the time to failure distribution, where the degradation process is modelled as a linear model using Bayesian inference. The proposed sequential analysis is based on an index that measures the expected discrepancy between the estimated quantile and its corresponding prediction, using Monte Carlo methods. The procedure was successfully implemented for simulated and real data.


Assuntos
Teorema de Bayes , Modelos Lineares , Método de Monte Carlo , Humanos , Reprodutibilidade dos Testes
11.
Stat Methods Med Res ; : 9622802241268504, 2024 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-39161324

RESUMO

The hazard function represents one of the main quantities of interest in the analysis of survival data. We propose a general approach for parametrically modelling the dynamics of the hazard function using systems of autonomous ordinary differential equations (ODEs). This modelling approach can be used to provide qualitative and quantitative analyses of the evolution of the hazard function over time. Our proposal capitalises on the extensive literature on ODEs which, in particular, allows for establishing basic rules or laws on the dynamics of the hazard function via the use of autonomous ODEs. We show how to implement the proposed modelling framework in cases where there is an analytic solution to the system of ODEs or where an ODE solver is required to obtain a numerical solution. We focus on the use of a Bayesian modelling approach, but the proposed methodology can also be coupled with maximum likelihood estimation. A simulation study is presented to illustrate the performance of these models and the interplay of sample size and censoring. Two case studies using real data are presented to illustrate the use of the proposed approach and to highlight the interpretability of the corresponding models. We conclude with a discussion on potential extensions of our work and strategies to include covariates into our framework. Although we focus on examples of Medical Statistics, the proposed framework is applicable in any context where the interest lies in estimating and interpreting the dynamics of the hazard function.

12.
Pilot Feasibility Stud ; 10(1): 104, 2024 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-39095876

RESUMO

BACKGROUND: People with mobility limitations have a disproportionately higher rate of acquiring secondary conditions such as obesity, cardiovascular comorbidity, pain, fatigue, depression, deconditioning, and type 2 diabetes. These conditions often result from poor access to home and community-based health promotion/wellness programs. The aim of this project was to determine the feasibility of delivering an online community membership-based fitness program for individuals with mobility impairments. METHODS: For this prospective single-arm study, participants were recruited from members of a community fitness facility that serves people with physical disabilities and chronic health conditions. While all members had access to the online platform, individuals had to opt-in to participate in the research component. Activity options included 16 pre-recorded videos and 9 live exercise classes. During the 8-week program, participants had an opportunity to earn three exercise incentives for reaching certain activity milestones. Enrollment percentage, attendance, and attrition were tracked to assess program feasibility and acceptability. Changes in participant-reported outcomes including self-reported physical activity, psychosocial outcomes, and health-related quality of life (HRQOL) were examined using non-parametric analyses. RESULTS: A total of 146 eligible individuals were screened of which 33 enrolled (22.6%). Two participants withdrew from the study, so a total of 31 were used for analyses. Participants included 29 women and 12 Black people with an average age of 60 (± 15.9) years. Health conditions included stroke, post-polio, arthritis, neuropathy, cerebral palsy, and obesity. Ten participants used an assistive device to get around inside the home. Twenty-six participants (78.8%) completed the online program, and 5 participants earned all 3 participation incentives. The mean number of live Zoom exercise classes attended by the participants was 12.8 (range = 0-43) over 8 weeks; 3 of 31 participants did not attend any classes. On average, participants watched 128 min (range = 0-704 min) of pre-recorded videos; 6 of 31 participants did not view any pre-recorded videos. Self-reported physical activity showed the largest improvement (11.15 units; 95% CI, 3.08, 19.56) with an effect size of 0.51 (Cohen's d). CONCLUSIONS: This pilot study of an online membership-based fitness program for people with mobility impairments demonstrated preliminary effectiveness in increasing physical activity and was found to be feasible and acceptable. Feasibility endpoints do indicate potential to improve retention. These results suggest that online delivery of exercise programs can broaden the reach of specialized community fitness programs and is a promising direction for future work and fully powered trials are warranted to assess intervention efficacy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05138809. Registered September 2, 2021, ClinicalTrials.gov PRS: Record Summary NCT05138809.

13.
Top Stroke Rehabil ; : 1-10, 2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38785263

RESUMO

BACKGROUND: When pedaling a coupled-crank arm ergometer, individuals with hemiplegia may experience nonparetic arm overcompensation, and paretic arm resistance, due to neuromechanical deficits. Technologies that foster independent limb contributions may increase the effectiveness of exercise for people poststroke. OBJECTIVE: Examine the speed during uncoupled pedaling with the Advanced Virtual Exercise Environment Device among individuals poststroke and non-impaired comparisons. METHODS: We recruited 2 groups:Poststroke and Comparison. Participants attended one lab session and performed peak speed tests and a graded exercise repeated for bilateral pedaling, unilateral (left, right). RESULTS: Thirty-one participants completed the protocol (16 women, 15 men). Poststroke participants pedaled slower during the bilateral speed test (64 ± 39 RPM, p < .001), and graded exercise, (54 ± 28 RPM, p < .001) versus comparisons (141 ± 19, 104 ± 12 RPM). Poststroke individuals had lower peak RPM during the unilateral speed test with their paretic arm (70 ± 46 RPM, p < .001) and graded exercise (58 ± 33 RPM, p < .001) compared to their unilateral speed test (130 ± 37 RPM) and graded exercise (108 ± 25 RPM) with their nonparetic arm. Comparisons did not differ between arms during speed tests and graded exercise. Poststroke participants demonstrated lower peak speed with their affected arm during the bilateral speed test (52 ± 42 RPM, p < .001) and graded exercise (49 ± 28 RPM, p = .008) compared to the same arm during unilateral speed (70 ± 46 RPM) and graded exercise (58 ± 33 RPM). CONCLUSIONS: Poststroke participants pedaled faster with their affected arm unilaterally versus bilateral pedaling, suggesting interhemispheric interference that reduces the ability to recruit the paretic arm during bilateral exercise.

14.
J Sports Med Phys Fitness ; 64(9): 863-870, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38842372

RESUMO

BACKGROUND: Exposure to hypoxia immediately challenges a variety of physiologic systems that limit exercise capacity. Under normoxia, caffeine (CAFF) increases ventilation and subsequent oxygenation of hemoglobin (SpO2) and skeletal muscle (SmO2). CAFF improves exercise performance at altitude. However, little attention has been given to submaximal exercise in hypoxia, particularly regarding low CAFF consumers and female participants. The aim of this study was to determine the effect of CAFF on pulmonary, metabolic, and perceptual variables in response to submaximal running in hypoxia in low CAFF consuming males and females. METHODS: In a double blinded, counterbalanced design, 14 (6 females) individuals (24.1±5.1 years; VO2max: 40.6±5.6 mL × kg-1 × min-1; 20.8±8.0% body fat), who habitually consumed ≤150 mg/day of CAFF performed treadmill running at workloads of 25%, 40%, 60%, and 75% of sea level VO2max in normobaric hypoxia (FIO2=0.15) on two separate occasions: 1) 60 minutes after 6 mg/kg of CAFF; or 2) placebo. RESULTS: CAFF had no effect on any variable measured. Specifically, VE (condition: P=0.12; interaction: P=0.19), VT (condition: P=0.16; interaction: P=0.57), and Ve:VO2 (condition: P=0.07; interaction: P=0.69) were similar between groups. Further, CAFF had no effect on relative VO2 (condition: P=0.84; interaction: P=0.95), HR (condition: P=0.28; interaction: P=0.35), SmO2 (condition: P=0.66; interaction: P=0.82), or SpO2 (condition: P=0.16; interaction: P=0.97). Finally, rating of perceived exertion (RPE; P=0.92) and acute mountain sickness scores (P=0.29) were similar across conditions. CONCLUSIONS: These data demonstrate that CAFF provides no physiologic advantage to submaximal exercise in acute, normobaric hypoxia with low CAFF consuming males and females.


Assuntos
Cafeína , Hipóxia , Corrida , Humanos , Cafeína/administração & dosagem , Corrida/fisiologia , Feminino , Masculino , Hipóxia/fisiopatologia , Método Duplo-Cego , Adulto , Adulto Jovem , Consumo de Oxigênio/fisiologia , Teste de Esforço , Frequência Cardíaca
15.
JMIR Rehabil Assist Technol ; 10: e41993, 2023 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-37535411

RESUMO

BACKGROUND: Video games are a popular sedentary activity among people with impaired mobility; however, active video game hardware typically lacks accessibility and customization options for individuals with mobility impairments. A touchpad video game system can elicit moderate physical activity in healthy adults; however, it is unclear if this system is usable by adults with impaired mobility. OBJECTIVE: The purpose of this study was to assess the usability of a touchpad video game controller system adapted for adults with impaired mobility. Additional outcomes explored were enjoyment, perceived exertion, self-efficacy, participant feedback, and researcher observations of gameplay. METHODS: Participants played several video game titles for 20 minutes with a touchpad video game controller as they stood or sat in a chair or their wheelchair. Usability was assessed with the System Usability Scale (SUS) and the Health Information Technology Usability Evaluation Scale (Health-ITUES) surveys after gameplay. After each video game, participants reported enjoyment using a visual analog scale (0 to 100 mm) and a rating of perceived exertion using the OMNI 0 to 10 scale. Self-efficacy was measured before and after gameplay. Participants provided feedback at the end of their session. RESULTS: In total, 21 adults (6 females and 15 males) with a mean age of 48.8 (SD 13.8) years with various mobility impairments participated in this study. The touchpads received mean usability scores on the SUS 80.1 (SD 18.5) and Health-ITUES 4.23 (SD 0.67). CONCLUSIONS: The SUS scores reported suggest the touchpad system is "usable"; however, the Health-ITUES scores were slightly below a suggested benchmark. Participants reported moderate to high enjoyment but perceived the exertion as "somewhat easy." Self-efficacy was moderate to high and did not differ pre- to postgame play. The participants regarded the touchpads as novel, fun, and entertaining. The generalizability of our results is limited due to the heterogenous sample; however, our participants identified several areas of improvement for future iteration.

16.
JMIR Form Res ; 7: e49685, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-38100173

RESUMO

BACKGROUND: People with disabilities experience numerous barriers to being physically active, such as transportation issues, a lack of trained exercise professionals who understand disabilities, and facility access. The use of a virtual exercise platform (VEP) may provide an alternative and limit certain barriers. OBJECTIVE: The aim of this mixed method study was to evaluate user interaction (effectiveness, efficiency, and satisfaction), the strengths and weaknesses of the user interface, and the user experience with a VEP. METHODS: Participants were recruited from a community fitness facility that offers programs for people with disabilities. Inclusion criteria were being older than 18 years, fluent in English, and availability of internet access. Features of the VEP included articles, prerecorded videos, live Zoom classes, web-based class registration, weekly progress tracking, incentives, and surveys. A one-on-one Zoom session was scheduled with each participant, during which they completed certain tasks: (1) create an account or login, (2) register for class, (3) join class, (4) add to calendar, and (5) complete surveys. As participants completed tasks, quantitative observations (time on task, task success, rate of task completion, and number of errors by users, which determined task difficulty), qualitative observations were made and interviews were conducted at the end of the session. The "concurrent think-aloud" method was encouraged by the moderator to gauge participants' thoughts as they worked through testing. Participants also completed the System Usability Scale (SUS) and Questionnaire for User Interface Satisfaction (QUIS). RESULTS: A total of 5 people with disabilities (3 male, 2 female), aged 36-78 (mean 54) years, with education levels from high school to PhD, were recruited. Devices used for testing included a laptop (n=3), a Chromebook (n=1), and a desktop (n=1). All participants completed tasks #1 and #2 without errors but could not complete task #4. One participant completed task #5 with difficulty and another completed task #3 with difficulty. The average time to complete each task was: (1) 82 seconds (55-110), (2) 11 seconds (4-21), (3) 9 seconds (5-27), and (4) 921.5 seconds (840-958). The mean SUS score was 86.5/100, and the mean user QUIS score was 8.08 out of 10. Qualitative observations indicated that the system was simple, user-friendly, and accessible. CONCLUSIONS: People with disabilities reported high usability and user satisfaction with the web-based exercise platform, and the system appears to be an efficient and effective physical activity option.

17.
Artigo em Inglês | MEDLINE | ID: mdl-36777952

RESUMO

We compared optimal antibiotic prescribing before and after implementing an interpretive ß-lactamase microbiology comment for Haemophilus influenzae and Moraxella catarrhalis in lower respiratory-tract infections. The postintervention group was associated with 5-fold increased odds of optimal de-escalation (adjusted odds ratio, 5.03; 95% confidence interval, 2.57-9.87).

18.
JMIR Serious Games ; 11: e38484, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36626195

RESUMO

BACKGROUND: Replacing sedentary behaviors during leisure time with active video gaming has been shown to be an enjoyable option for increasing physical activity. However, most off-the-shelf active video gaming controllers are not accessible or usable for individuals with mobility impairments. To address this requirement, a universal video game controller (called the GAIMplank) was designed and developed. OBJECTIVE: This study aimed to assess the usability of the GAIMplank video game controller for playing PC video games among individuals with mobility impairments. Measures of enjoyment, perceived exertion, and qualitative data on the user experience were also examined. METHODS: Adults (aged 18-75 years) with a mobility impairment were recruited to participate in a single testing session in the laboratory. Before testing began, basic demographic information, along with minutes of weekday and weekend physical activity, minutes of weekday and weekend video game play, and video game play experience were collected. The GAIMplank was mapped to operate as a typical joystick controller. Depending on their comfort and functional ability, participants chose to play seated in a chair, standing, or in their own manual wheelchair. Leaning movements of the trunk created corresponding action in the game (ie, lean right to move right). The participants played a total of 5 preselected video games for approximately 5 minutes each. Data were collected to assess the usability of the GAIMplank, along with self-efficacy regarding execution of game play actions, rating of perceived exertion and enjoyment for each game, and overall qualitative feedback. RESULTS: A total of 21 adults (n=15, 71% men; n=6, 29% women) completed the usability testing, with a mean age of 48.8 (SD 13.8; range 21-73) years. Overall, 38% (8/21) of adults played while standing, 33% (7/21) of adults played while seated in a chair, and 29% (6/21) played in their own manual wheelchair. Scores from the System Usability Scale indicated above average (74.8, SD 14.5) usability, with scores best for those who played seated in a chair, followed by those standing, and then individuals who played seated in their own wheelchairs. Inconsistencies in the responsiveness of the controller and general feedback for minor improvements were documented. Rating of perceived exertion scores ranged from light to moderate intensity, with the highest scores for those who played seated in a chair. Participants rated their experience with playing each game from above average to very enjoyable. CONCLUSIONS: The GAIMplank video game controller was found to be usable and accessible, providing an enjoyable option for light-to-moderate intensity exercise among adults with mobility impairments. Minor issues with inconsistencies in controller responsiveness were also recorded. Following further development and refinement, the next phase will include a pilot exercise intervention using the GAIMplank system.

19.
Microb Physiol ; 33(1): 49-62, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37321192

RESUMO

Members of the Piezo family of mechanically activated cation channels are involved in multiple physiological processes in higher eukaryotes, including vascular development, cell differentiation, touch perception, hearing, and more, but they are also common in single-celled eukaryotic microorganisms. Mutations in these proteins in humans are associated with a variety of diseases, such as colorectal adenomatous polyposis, dehydrated hereditary stomatocytosis, and hereditary xerocytosis. Available 3D structures for Piezo proteins show nine regions of four transmembrane segments each that have the same fold. Despite the remarkable similarity among the nine characteristic structural repeats in the family, no significant sequence similarity among them has been reported. Using bioinformatics approaches and the Transporter Classification Database (TCDB) as reference, we reliably identified sequence similarity among repeats based on four lines of evidence: (1) hidden Markov model-profile similarities across repeats at the family level, (2) pairwise sequence similarities between different repeats across Piezo homologs, (3) Piezo-specific conserved sequence signatures that consistently identify the same regions across repeats, and (4) conserved residues that maintain the same orientation and location in 3D space.


Assuntos
Toxinas Bacterianas , Clostridioides difficile , Humanos , Clostridioides difficile/metabolismo , Canais Iônicos/genética , Canais Iônicos/química , Canais Iônicos/metabolismo , Mutação , Sequência Conservada
20.
Nanotechnology ; 23(33): 335201, 2012 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-22842356

RESUMO

The heteroepitaxy of III-V semiconductors on silicon is a promising approach for making silicon a photonic platform. Mismatches in material properties, however, present a major challenge, leading to high defect densities in the epitaxial layers and adversely affecting radiative recombination processes. However, nanostructures, such as quantum dots, have been found to grow defect-free even in a suboptimal environment. Here we present the first realization of indium phosphide quantum dots on exactly oriented Si(001), grown by metal-organic vapour-phase epitaxy. We report electrically driven single-photon emission in the red spectral region, meeting the wavelength range of silicon avalanche photodiodes' highest detection efficiency.

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