Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.480
Filtrar
Más filtros

Intervalo de año de publicación
1.
Semin Cell Dev Biol ; 133: 74-82, 2023 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-35365398

RESUMEN

Cells with subcellular lumens form some of the most miniature tubes in the tubular organs of animals. These are often crucial components of the system, executing functions at remote body locations. Unlike tubes formed by intercellular or autocellular junctions, the cells with junctionless subcellular lumens face unique challenges in modifying the cell shape and plasma membrane organization to incorporate a membrane-bound tube within, often associated with dramatic cellular growth and extensions. Results in the recent years have shown that membrane dynamics, including both the primary delivery and recycling, is crucial in providing the cell with the flexibility to face these challenges. A significant portion of this information has come from two in vivo invertebrate models; the Drosophila tracheal terminal cells and the C. elegans excretory cell. This review focuses on the data obtained from these systems in the recent past about how trafficking pathways influence subcellular tube and branching morphogenesis. Given that such tubes occur in vertebrate vasculature, these insights are relevant to human health, and we contrast our conclusions with the less understood subcellular tubes of angiogenesis.


Asunto(s)
Proteínas de Drosophila , Animales , Humanos , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Caenorhabditis elegans/metabolismo , Morfogénesis , Drosophila/metabolismo
2.
Nano Lett ; 24(5): 1587-1593, 2024 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-38259044

RESUMEN

Magnetic skyrmions in bulk materials are typically regarded as two-dimensional structures. However, they also exhibit three-dimensional configurations, known as skyrmion tubes, that elongate and extend in-depth. Understanding the configurations and stabilization mechanism of skyrmion tubes is crucial for the development of advanced spintronic devices. However, the generation and annihilation of skyrmion tubes in confined geometries are still rarely reported. Here, we present direct imaging of skyrmion tubes in nanostructured cuboids of a chiral magnet FeGe using Lorentz transmission electron microscopy (TEM), while applying an in-plane magnetic field. It is observed that skyrmion tubes stabilize in a narrow field-temperature region near the Curie temperature (Tc). Through a field cooling process, metastable skyrmion tubes can exist in a larger region of the field-temperature diagram. Combining these experimental findings with micromagnetic simulations, we attribute these phenomena to energy differences and thermal fluctuations. Our results could promote topological spintronic devices based on skyrmion tubes.

3.
Plant J ; 114(3): 651-667, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36811355

RESUMEN

Polyadenylation of mRNAs is critical for their export from the nucleus, stability, and efficient translation. The Arabidopsis thaliana genome encodes three isoforms of canonical nuclear poly(A) polymerase (PAPS) that redundantly polyadenylate the bulk of pre-mRNAs. However, previous studies have indicated that subsets of pre-mRNAs are preferentially polyadenylated by either PAPS1 or the other two isoforms. Such functional specialization raises the possibility of an additional level of gene-expression control in plants. Here we test this notion by studying the function of PAPS1 in pollen-tube growth and guidance. Pollen tubes growing through female tissue acquire the competence to find ovules efficiently and upregulate PAPS1 expression at the transcriptional, but not detectably at the protein level compared with in vitro grown pollen tubes. Using the temperature-sensitive paps1-1 allele we show that PAPS1 activity during pollen-tube growth is required for full acquisition of competence, resulting in inefficient fertilization by paps1-1 mutant pollen tubes. While these mutant pollen tubes grow almost at the wild-type rate, they are compromised in locating the micropyles of ovules. Previously identified competence-associated genes are less expressed in paps1-1 mutant than in wild-type pollen tubes. Estimating the poly(A) tail lengths of transcripts suggests that polyadenylation by PAPS1 is associated with reduced transcript abundance. Our results therefore suggest that PAPS1 plays a key role in the acquisition of competence and underline the importance of functional specialization between PAPS isoforms throughout different developmental stages.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Tubo Polínico/metabolismo , Proteínas de Arabidopsis/metabolismo , Polinucleotido Adenililtransferasa/genética , Isoformas de Proteínas/metabolismo , Mutación
4.
J Biomol NMR ; 2024 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-39066955

RESUMEN

Fluorine (19F) NMR is emerging as an invaluable analytical technique in chemistry, biochemistry, structural biology, material science, drug discovery, and medicine, especially due to the inherent rarity of naturally occurring fluorine in biological, organic, and inorganic compounds. Here, we revisit the under-reported problem of fluoride leaching from new and unused glass NMR tubes. We characterised the leaching of free fluoride from various types of new and unused glass NMR tubes over the course of several hours and quantify this contaminant to be at micromolar concentrations for typical NMR sample volumes across multiple glass types and brands. We find that this artefact is undetectable for samples prepared in quartz NMR tubes within the timeframes of our experiments. We also observed that pre-soaking new glass NMR tubes combined with rinsing removes this contamination below micromolar levels. Given the increasing popularity of 19F NMR across a wide range of fields, increasing popularity of single-use screening tubes, the long collection times required for relaxation studies and samples of low concentrations, and the importance of avoiding contamination in all NMR experiments, we anticipate that our simple solution will be useful to biomolecular NMR spectroscopists.

5.
Small ; 20(11): e2307491, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37880860

RESUMEN

The environmental monitoring and remediation of highly toxic inorganic arsenic species in natural water are needed for the benefit of the ecosystem. Current studies on arsenic detection and removal often employ separate materials, which exhibit blue luminescence with fluorescence quenching, making them unsuitable for biological and environmental samples. In this study, carbon dot-embedded mesoporous silica tubes functionalized with melamine are synthesized to address these limitations and enable specific and turn-on probing of inorganic arsenic. The newly synthesized material demonstrates excitation-independent yellow luminescence and can effectively detect both As (III) and As (V) at low detection limits (11 × 10-9 m, 11.2 × 10-9 m), well below the prescribed threshold limits in drinking water. It also exhibits a high adsorption capacity (≈125, 159 mg g-1 ) with fast kinetics. The material's applicability in environmental samples is validated through the successful quantification of arsenic in real samples with satisfactory recoveries. Moreover, the material shows recyclability for reuse, as demonstrated by its arsenic adsorption and desorption for several cycles under basic conditions. Additionally, the material's capability for monitoring arsenic in a biological sample (Artemia salina) is demonstrated through fluorescence imaging. The encouraging outcomes underscore the material's potential use in monitoring and mitigating arsenic in aqueous systems.


Asunto(s)
Arsénico , Arsenicales , Agua Potable , Contaminantes Químicos del Agua , Purificación del Agua , Arsénico/análisis , Carbono , Dióxido de Silicio , Ecosistema , Adsorción , Cinética , Concentración de Iones de Hidrógeno , Purificación del Agua/métodos
6.
Small ; 20(14): e2306272, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37988649

RESUMEN

Precise control of pore volume and size of carbon nanoscale materials is crucial for achieving high capacity and rate performances of charge/discharge. In this paper, starting from the unique mechanism of the role of In, Zn combination, and carboxyl functional groups in the formation of the lumen and pore size, the composition of InZn-MIL-68 is regulated to precisely tune the diameter and wall pore size of the hollow carbon tubes. The hollow carbon nanotubes (CNT) with high-capacity storage and fast exchange of Na+ ions and charges are prepared. The CNT possess ultra-high specific capacitance and ultra-long cycle life and also offer several times higher Na+ ion storage capacity and rate performance than the existing CNTs. Density functional theory calculations and tests reveal that these superior characteristics are attributed to the spacious hollow structure, which provides sufficient space for Na+ storage and the tube wall's distinctive porosity of tube wall as well as open ends for facilitating Na+ rapid desorption. It is believed that precise control of sub-nanopore volume and pore size by tuning the composition of the carbon materials derived from bimetallic metal-organic frameworks (MOFs) will establish the basis for the future development of high-energy density and high-power density supercapacitors and batteries.

7.
Small ; : e2402389, 2024 May 17.
Artículo en Inglés | MEDLINE | ID: mdl-38757548

RESUMEN

Inspired by the sophisticated multicomponent and multistage assembly of proteins and their mixtures in living cells, this study rationally designs and fabricates photoresponsive colloidal tubes that can self-assemble and hybrid-assemble when mixed with colloidal spheres and rods. Time-resolved observation and computer simulation reveal that the assembly is driven by phoretic attraction originating from osmotic pressures. These pressures are induced by the chemical concentration gradients generated by the photochemical reaction caused by colloidal tubes in a H2O2 solution under ultraviolet (UV) irradiation. The assembled structure is dictated by the size and shape of the constituent colloids as well as the intensity of the UV irradiation. Additionally, the resulting assembly can undergo self-propelled motion originating from the broken symmetry of the surrounding concentration gradients. This motion can be steered by a magnetic field and used for microscale cargo delivery. The study demonstrates a facile synthesis method for colloidal tubes and highlights their unique potential for controlled, hierarchical self-assembly and hybrid-assembly.

8.
Small ; 20(25): e2309067, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38189642

RESUMEN

To date, the excellent mass-catalytic activities of Pt single-atoms catalysts (Pt-SACs) toward hydrogen evolution reaction (HER) are categorically confirmed; however, their high current density performance remains a challenge for practical applications. Here, a binder-free approach is exemplified to fabricate self-standing superhydrophilic-superaerphobic Pt-SACs cathodes by directly anchoring Pt-SAs via Pt-NxC4-x coordination bonds to the structurally-integrated 3D nitrogen-doped carbon tubes (N-CTs) array grid (denoted as Pt@N-CTs). The 3D Pt@N-CTs cathode with optimal Pt-SACs loading is capable of operating at a high current density of 1000 mA cm-2 with an ultralow overpotential of 157.9 mV with remarkable long-term stability over 11 days at 500 mA cm-2. The 3D super-wettable free-standing Pt@N-CTs possess interconnected vertical and lateral N-CTs with hierarchical-sized open channels, which facilitates the mass transfer. The binder-free immobilization adding to the large surface area and 3D-interconnected open channels endow Pt@N-CTs cathodes with high accessible active sites, electrical conductivity, and structural stability that maximize the utilization efficiency of Pt-SAs to achieve ampere-level current density HER at low overpotentials.

9.
Biochem Soc Trans ; 52(3): 1449-1457, 2024 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-38747723

RESUMEN

Protein-mediated membrane fission has been analyzed both in bulk and at the single event resolution. Studies on membrane fission in vitro using tethers have provided fundamental insights into the process but are low in throughput. In recent years, supported membrane template (SMrT) have emerged as a facile and convenient assay system for membrane fission. SMrTs provide useful information on intermediates in the pathway to fission and are therefore high in content. They are also high in throughput because numerous fission events can be monitored in a single experiment. This review discusses the utility of SMrTs in providing insights into fission pathways and its adaptation to annotate membrane fission functions in proteins.


Asunto(s)
Membrana Celular , Membrana Celular/metabolismo , Proteínas de la Membrana/metabolismo , Humanos , Ensayos Analíticos de Alto Rendimiento/métodos , Animales
10.
J Exp Bot ; 75(14): 4415-4427, 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-38877792

RESUMEN

Major constituents of the plant cell walls are structural proteins that belong to the hydroxyproline-rich glycoprotein (HRGP) family. Leucine-rich repeat extensin (LRX) proteins contain a leucine-rich domain and a C-terminal domain with repetitive Ser-Pro3-5 motifs that are potentially to be O-glycosylated. It has been demonstrated that pollen-specific LRX8-LRX11 from Arabidopsis thaliana are necessary to maintain the integrity of the pollen tube cell wall during polarized growth. In HRGPs, including classical extensins (EXTs), and probably in LRXs, proline residues are converted to hydroxyproline by prolyl-4-hydroxylases (P4Hs), thus defining novel O-glycosylation sites. In this context, we aimed to determine whether hydroxylation and subsequent O-glycosylation of Arabidopsis pollen LRXs are necessary for their proper function and cell wall localization in pollen tubes. We hypothesized that pollen-expressed P4H4 and P4H6 catalyze the hydroxylation of the proline units present in Ser-Pro3-5 motifs of LRX8-LRX11. Here, we show that the p4h4-1 p4h6-1 double mutant exhibits a reduction in pollen germination rates and a slight reduction in pollen tube length. Pollen germination is also inhibited by P4H inhibitors, suggesting that prolyl hydroxylation is required for pollen tube development. Plants expressing pLRX11::LRX11-GFP in the p4h4-1 p4h6-1 background show partial re-localization of LRX11-green fluorescent protein (GFP) from the pollen tube tip apoplast to the cytoplasm. Finally, immunoprecipitation-tandem mass spectrometry analysis revealed a decrease in oxidized prolines (hydroxyprolines) in LRX11-GFP in the p4h4-1 p4h6-1 background compared with lrx11 plants expressing pLRX11::LRX11-GFP. Taken together, these results suggest that P4H4 and P4H6 are required for pollen germination and for proper hydroxylation of LRX11 necessary for its localization in the cell wall of pollen tubes.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Tubo Polínico , Prolil Hidroxilasas , Arabidopsis/metabolismo , Arabidopsis/genética , Hidroxilación , Tubo Polínico/crecimiento & desarrollo , Tubo Polínico/metabolismo , Tubo Polínico/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Prolil Hidroxilasas/metabolismo , Prolil Hidroxilasas/genética , Pared Celular/metabolismo
11.
Microvasc Res ; 153: 104659, 2024 05.
Artículo en Inglés | MEDLINE | ID: mdl-38286222

RESUMEN

INTRODUCTION: Contrast-associated acute kidney injury (CA-AKI) is characterized as a loss of renal function following radiological contrast media administration. While all contrast media induce variable changes in microvascular endothelial cells in vitro, only few studies report clinical significance of their findings. A comprehensive assessment of the effect of iodinated contrast media on the renal function in vitro and in vivo is essential. The aim of our study was to morphometrically quantify the effect of two different contrast media (Iobitridol and Iodixanol) on vascular endothelial capillaries in vitro and to analyze their effect on the renal function of patients who underwent cardiac catheterization including the intra-arterial administration of contrast media, by measuring serum creatinine concentration (SCr), a byproduct of muscle metabolism, primarily excreted by the kidneys. Our hypothesis suggests that conducting a qualitative comparison of both outcomes will enable identification of differences and similarities between in vitro and in vivo exposure. MATERIAL AND METHODS: In vitro, co-cultures of human dermal fibroblasts and human dermal microvascular endothelial cells forming capillary beds were exposed to a mixture of phosphate buffered saline and either Iobitridol, Iodixanol, or one of their supplements EDTA or Trometamol for 1.5 or 5 min. Negative control co-cultures were exposed exclusively to phosphate buffered saline. Co-cultures were either directly fixed or underwent a regeneration time of 1, 3 or 7 days. An artificial intelligence software was trained for detection of labeled endothelial capillaries (CD31) on light microscope images and measurements of morphometric parameters. In vivo, we retrospectively analyzed data from patients who underwent intra-arterial administration of contrast media and for whom SCr values were available pre- and post-contrast exposition (1, 3, and 7 days following procedure). Temporal development of SCr and incidence of CA-AKI were assessed. Both exposure types were qualitatively compared. RESULTS: In vitro, Iobitridol, Iodixanol and EDTA induced a strong decrease of two morphometric parameters after 3 days of regeneration. In vivo, a significant increase of SCr and incidence of CA-AKI was observed 3 days following procedure in the post-contrast media patients. No difference was observed between groups. DISCUSSION: Two of the morphometric parameters were inversely proportional to the SCr of the patients. If the endothelial damages observed in vitro occur in vivo, it may result in renal hypoxia, inducing a loss of kidney function clinically translated into an increase of SCr. Further development of our in vitro model could allow closer replication of the internal structure of a kidney and bridge the gap between in vitro studies and their clinical findings.


Asunto(s)
Lesión Renal Aguda , Medios de Contraste , Yohexol/análogos & derivados , Ácidos Triyodobenzoicos , Humanos , Medios de Contraste/efectos adversos , Creatinina , Estudios Retrospectivos , Células Endoteliales , Inteligencia Artificial , Ácido Edético , Cateterismo Cardíaco/efectos adversos , Lesión Renal Aguda/inducido químicamente , Lesión Renal Aguda/diagnóstico , Lesión Renal Aguda/epidemiología , Fosfatos
12.
J Nutr ; 154(4): 1165-1174, 2024 04.
Artículo en Inglés | MEDLINE | ID: mdl-38311065

RESUMEN

BACKGROUND: The recommended transition toward more plant-based diets, particularly containing legumes, requires a wider knowledge of plant protein bioavailability. Faba beans are cultivated at different latitudes and are used increasingly in human nutrition. OBJECTIVES: We aimed to assess the nutritional quality of faba bean protein in healthy volunteers equipped with an intestinal tube to implement the ileal 15N balance method. METHODS: Nine volunteers completed the study (7 males, 2 females, aged 33 ± 10 y, BMI: 24.7 ± 2.6 kg/m2). They were equipped with a nasoileal tube. After fasting overnight, they ingested a test meal consisting of cooked mash of dehulled faba bean seeds (20 g protein per serving of approximately 250 g) intrinsically labeled with 15N. Samples of ileal contents, plasma, and urine were collected over an 8-h postprandial period. Undigested nitrogen (N) and amino acids (AAs) were determined using isotopic MS, and subsequently, ileal digestibility and digestible indispensable amino acid score (DIAAS) were calculated. The measurement of postprandial deamination allowed calculation of the net postprandial protein utilization (NPPU). RESULTS: The ileal N digestibility was 84.1% ± 7.7%. Postprandial deamination represented 19.2% ± 3.6% of ingested N, and the NPPU was 64.7% ± 9.7%. The ileal digestibility of individual AAs varied from 85.1% ± 13.7% for histidine to 94.2% ± 3.6% for glutamine + glutamate. The mean AA digestibility was ∼6 percentage points higher than the digestibility of N, reaching 89.8% ± 5.9%, whereas indispensable AA digestibility was 88.0% ± 7.3%. Histidine and tryptophan were the first limiting AAs [DIAAS = 0.77 (calculated by legume-specific N-to-protein conversion factor 5.4); 0.67 (by default factor 6.25)]. Sulfur AAs were limiting to a lesser extent [DIAA ratio = 0.94 (N × 5.4); 0.81 (N × 6.25)]. CONCLUSIONS: Protein ileal digestibility of cooked, dehulled faba beans in humans was moderate (<85%), but that of AAs was close to 90%. Overall protein quality was restricted by the limited histidine and tryptophan content. This trial was registered at clinicaltrials.gov as NCT05047757.


Asunto(s)
Fabaceae , Vicia faba , Femenino , Humanos , Masculino , Aminoácidos/metabolismo , Alimentación Animal , Dieta , Proteínas en la Dieta/metabolismo , Digestión , Fabaceae/química , Histidina/metabolismo , Íleon/metabolismo , Triptófano/metabolismo , Vicia faba/metabolismo
13.
BMC Cancer ; 24(1): 263, 2024 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-38402391

RESUMEN

BACKGROUND: Whether Transanal drainage tubes (TDTs) placement reduces the occurrence of anastomotic leakage (AL) after rectal cancer (RC) surgery remains controversial. Most existing meta-analyses rely on retrospective studies, while the prospective studies present an inadequate level of evidence. METHODS: A systematic review and meta-analysis of prospective studies on TDTs placement in RC patients after surgery was conducted. The main analysis index was the incidence of AL, Grade B AL, and Grade C AL, while secondary analysis index was the incidence of anastomotic bleeding, incision infection, and anastomotic stenosis. A comprehensive literature search was performed utilizing the databases Cochrane Library, Embase, PubMed, and Web of Science. We recorded Risk ratios (RRs) and 95% confidence intervals (CI) for each included study, and a fixed-effect model or random-effect model was used to investigate the correlation between TDTs placement and four outcomes after RC surgery. RESULTS: Seven studies (1774 participants, TDT 890 vs non-TDT 884) were considered eligible for quantitative synthesis and meta-analysis. The meta-analysis revealed that the incidence of AL was 9.3% (83/890) in the TDT group and 10.2% (90/884) in the non-TDT group. These disparities were found to lack statistical significance (P = 0.58). A comprehensive meta-analysis, comprising four studies involving a cumulative sample size of 1259 participants, revealed no discernible disparity in the occurrence of Grade B AL or Grade C AL between the TDT group and the non-TDT group (Grade B AL: TDT 34/631 vs non-TDT 26/628, P = 0.30; Grade C AL: TDT 11/631 vs non-TDT 27/628, P = 0.30). Similarly, the incidences of anastomotic bleeding (4 studies, 876 participants), incision infection (3studies, 713 participants), and anastomotic stenosis (2studies, 561 participants) were 5.5% (24/440), 8.1% (29/360), and 2.9% (8/280), respectively, in the TDT group, and 3.0% (13/436), 6.5% (23/353), and 3.9% (11/281), respectively, in the non-TDT group. These differences were also determined to lack statistical significance (P = 0.08, P = 0.43, P = 0.48, respectively). CONCLUSION: The placement of TDTs does not significantly affect the occurrence of AL, Grade B AL, and Grade C AL following surgery for rectal cancer. Additionally, TDTs placement does not be associated with increased complications such as anastomotic bleeding, incision infection, or anastomotic stenosis. TRIAL REGISTRATION: PROSPERO: CRD42023427914.


Asunto(s)
Fuga Anastomótica , Drenaje , Neoplasias del Recto , Humanos , Fuga Anastomótica/etiología , Fuga Anastomótica/epidemiología , Neoplasias del Recto/cirugía , Incidencia , Drenaje/métodos , Canal Anal/cirugía
14.
Chemphyschem ; 25(15): e202400362, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-38714496

RESUMEN

High temperature dissociations of organic molecules typically involve a competition between radical and molecular processes. In this work, we use a modeling, experiment, theory (MET) framework to characterize the high temperature thermal dissociation of CH2F2, a flammable hydrofluorocarbon (HFC) that finds widespread use as a refrigerant. Initiation in CH2F2 proceeds via a molecular elimination channel; CH2F2→CHF+HF. Here we show that the subsequent self-reactions of the singlet carbene, CHF, are fast multichannel processes and a facile source of radicals that initiate rapid chain propagation reactions. These have a marked influence on the decomposition kinetics of CH2F2. The inclusion of these reactions brings the simulations into better agreement with the present and literature experiments. Additionally, flame simulations indicate that inclusion of the CHF+CHF multichannel reaction leads to a noticeable enhancement in predictions of laminar flame speeds, a key parameter that is used to determine the flammability of a refrigerant.

15.
Anim Cogn ; 27(1): 41, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38805046

RESUMEN

Potential metacognitive abilities, such as monitoring and controlling cognitive processes, have been revealed in some primate species. In the tubes task, apes and macaques showed higher content-checking behavior when unaware of a reward's location, but they also periodically inspected the tubes when aware, especially when a more appealing reward was involved. Some attribute this to the pleasure of looking at the reward. This study investigates whether the unnecessary tube-checking behavior observed in nine wild Japanese macaques, previously tested for metacognition using the tubes task, can be solely attributed to impulsivity. The macaques' propensity to look inside a single tube containing food they cannot immediately reach was measured and compared to their behavior in the tubes task. Results indicated that looking inside the baited tube increased as reward quality improved. However, macaques displaying unnecessary tube inspections in metacognitive tests showed less impulsivity to look. This intriguing result counters the notion that excessive looking in the tubes task is solely due to impulsive looking, prompting us to advocate for further research into the relationship between inhibition and metacognitive performance.


Asunto(s)
Conducta Impulsiva , Macaca fuscata , Metacognición , Recompensa , Animales , Masculino , Femenino , Conducta Animal
16.
Ann Bot ; 2024 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-39136192

RESUMEN

BACKGROUND AND AIMS: Pollination failure occurs from insufficient pollen quantity or quality. However, the relative contributions of pollen quantity vs quality to overall pollen limitation, and how this is affected by the co-flowering context, remain unknown for most plant populations. Here, we studied patterns of pollen deposition and pollen tube formation across populations of four predominately outcrossing species in the genus Clarkia to evaluate how richness of co-flowering congeners affects the contribution of pollen quantity and quality to pollen limitation. METHODS: We partition variation in pollen deposition and pollen tube production across individuals, populations and species to identify the main sources of variation in components of reproductive success. We further quantify the relative contribution of pollen quantity and quality limitation to the reproductive success of the four Clarkia species using piecewise regression analyses. Finally, we evaluate how variation in the number of co-flowering Clarkia species in the community affects the strength of pollen quality and quality limitation. RESULTS: Across all contexts, pollen deposition and the proportion of pollen tubes produced varied greatly among individuals, populations, and species, and these were not always correlated. For instance, C. xantiana received the smallest pollen loads yet produced the highest proportion of pollen tubes, while C. speciosa exhibited the opposite pattern. Yet, co-flowering richness had variable effects on the strength of pollen quantity and quality limitation among populations. Specifically, breakpoint values, which are an indicator of overall pollen limitation, were two times larger in the four-species community compared with one and two-species communities for two Clarkia species, suggesting that pollen limitation can increase with increasing richness of co-flowering congeners. CONCLUSIONS: Our results reveal a complex interplay between quantity and quality of pollen limitation and co-flowering context that may have different evolutionary outcomes across species and populations.

17.
Periodontol 2000 ; 2024 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-38778518

RESUMEN

Currently, autologous platelet concentrates (APCs) are frequently used for soft- and hard-tissue regeneration, not only within the oral cavity, but also extra-orally including chronic wounds, burns, joints, dermatological conditions, among others. The benefits of APCs are largely influenced by the treatment strategy but also their preparation. This paper therefore discusses in detail: the physical properties of blood cells, the basic principles of blood centrifugation, the impact of the centrifugation protocol (rotations/revolutions per minute, g-force, variation between centrifuges), the importance of timing during the preparation of APCs, the impact of the inner surface of the blood tubes, the use/nonuse of anticoagulants within APC tubes, the impact of the patient's hematocrit, age, and gender, as well as the important requirements for an optimal centrifugation protocol. All these variables indeed have a significant impact on the clinical outcome of APCs.

18.
Clin Chem Lab Med ; 62(9): 1835-1844, 2024 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-38593236

RESUMEN

OBJECTIVES: Integration of add-on testing in high-scale automated clinical laboratories constitute a valuable instrument not only for the clinicians and the general patient care, but also for the laboratory itself. Knowledge on sample quality and analytical stability upon storage is necessary to be able to offer add-on testing. The objectives of this study were to examine the analytical stability of 63 biochemical analytes in plasma and urine samples stored at 16 °C. METHODS: Samples were collected by professional laboratory technicians, analyzed at automated analyzers and stored in their primary, capped tube without separator for 10, 12, 16, 20 or 24 h at 16 °C. Stability was assessed by inspecting mean concentration of samples at baseline and examining if (A) mean concentration over time violated limits of bias, or if (B) individual sample concentrations violated limits of total error. RESULTS: The majority of the 63 analytes were stable for up to 24 h of storage. Few of the analytes were only suitable for add-on testing for 4, 6, 10, 12, 16 or 20 h of storage. One analyte, P-lactate dehydrogenase, was not found suitable for add-on testing when stored at 16 °C. CONCLUSIONS: Due to the increasing number of intelligent solutions for high-scale clinical laboratories, add-on testing has come to stay. Loss of stability could not be demonstrated for the majority of analytes after 10, 12, 16, 20 or 24 h of storage. This feature of analytical stability suggests that add-on testing is an acceptable tool for these analytes.


Asunto(s)
Manejo de Especímenes , Humanos , Manejo de Especímenes/normas , Temperatura , Factores de Tiempo
19.
Environ Res ; 252(Pt 2): 118927, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38631467

RESUMEN

Effective drug delivery for is the foremost requirement for the complete recovery of the disease. Nanomedicine and nanoengineering has provided so many spaces and ideas for the drug delivery design, whether controlled, targeted, or sustained. Different types of nanocarriers or nanoparticles are aggressively designed for the drug delivery applications. Clay minerals are identified as a one of the potential nanocarrier for the drug delivery. Owing to their biocompatibility and very low cytotoxicity, clay minerals showing effective therapeutic applications. In the present investigation, clay mineral, i.e., Halloysite nano tubes are utilized as a nanocarrier for the delivery of antibiotic cefixime (CFX), a third-generation cephalosporin. The HNT was first functionalized with the sulfuric acid and then further treated with the 3-(aminopropyl)triethoxysilane (APTES). The drug is loaded on three different classifications of HNTs, i.e., Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT and their comparative analysis is established. Different characterization techniques such as X-ray diffractometry (XRD), Fourier transform infra-red (FT-IR), Transmission electron microscopy TEM), Brunauer-Emmett-Teller (BET), adsorption studies, and Thermogravimetric analysis (TGA) were performed to evaluate their chemical, structural, morphological, and thermal properties. TGA confirmed the encapsulation efficiency of Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT as 42.65, 52.19, and 53.43%, respectively. Disk diffusion and MTT assay confirmed that the drug loaded HNTs have potential antibacterial activities and less cytotoxicity. The adsorption capacity of CFX with different HNTs are evaluated and Different adsorption and kinetic models have been discussed. Drug release studies shows that APTES-CFX-HNT showing sustained release of cefixime as compared to Bare-CFX-HNT and Acid-CFX-HNT.


Asunto(s)
Antibacterianos , Cefixima , Arcilla , Cefixima/química , Antibacterianos/química , Arcilla/química , Portadores de Fármacos/química , Silicatos de Aluminio/química , Nanopartículas/química , Silanos/química , Espectroscopía Infrarroja por Transformada de Fourier , Propilaminas
20.
Dig Dis Sci ; 69(5): 1534-1536, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38564147

RESUMEN

Direct percutaneous endoscopic jejunostomy (DPEJ) provides post-pyloric enteral access in patients unable to meet long-term nutritional needs per os in situations where gastric feeding is neither tolerated nor feasible. Specific conditions associated with feeding intolerance due to due to nausea, vomiting, or ileus include gastric outlet obstruction, gastroparesis, or complications of acute or chronic pancreatitis; infeasibility may be due to high aspiration risk or prior gastric surgery. Since performing DPEJ is not an ACGME requirement for GI fellows or early career gastroenterologists, not all trainees are taught this technique. Hence, provider expertise for teaching and performing this technique varies widely across centers. In this article, we provide top tips for successful performance of DPEJ.


Asunto(s)
Nutrición Enteral , Yeyunostomía , Humanos , Yeyunostomía/métodos , Nutrición Enteral/métodos , Nutrición Enteral/instrumentación , Endoscopía Gastrointestinal/métodos , Intubación Gastrointestinal/métodos , Intubación Gastrointestinal/instrumentación
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA