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1.
J Pediatr Surg ; 2024 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-38955625

RESUMEN

BACKGROUND: Radiographic diagnosis of necrotizing enterocolitis (NEC) is challenging. Deep learning models may improve accuracy by recognizing subtle imaging patterns. We hypothesized it would perform with comparable accuracy to that of senior surgical residents. METHODS: This cohort study compiled 494 anteroposterior neonatal abdominal radiographs (214 images NEC, 280 other) and randomly divided them into training, validation, and test sets. Transfer learning was utilized to fine-tune a ResNet-50 deep convolutional neural network (DCNN) pre-trained on ImageNet. Gradient-weighted Class Activation Mapping (Grad-CAM) heatmaps visualized image regions of greatest relevance to the pretrained neural network. Senior surgery residents at a single institution examined the test set. Resident and DCNN ability to identify pneumatosis on radiographic images were measured via area under the receiver operating curves (AUROC) and compared using DeLong's method. RESULTS: The pretrained neural network achieved AUROC of 0.918 (95% CI, 0.837-0.978) with an accuracy of 87.8% with five false negative and one false positive prediction. Heatmaps confirmed appropriate image region emphasis by the pretrained neural network. Senior surgical residents had a median area under the receiver operating curve of 0.896, ranging from 0.778 (95% CI 0.615-0.941) to 0.991 (95% CI 0.971-0.999) with zero to five false negatives and one to eleven false positive predictions. The deep convolutional neural network performed comparably to each surgical resident's performance (p > 0.05 for all comparisons). CONCLUSIONS: A deep convolutional neural network trained to recognize pneumatosis can quickly and accurately assist clinicians in promptly identifying NEC in clinical practice. LEVEL OF EVIDENCE: III (study type: Study of Diagnostic Test, study of nonconsecutive patients without a universally applied "gold standard").

2.
Diagn Microbiol Infect Dis ; 110(1): 116421, 2024 Jul 04.
Artículo en Inglés | MEDLINE | ID: mdl-38972132

RESUMEN

We assessed the performance of three different multiplex lateral flow assays manufactured by SureScreen, Microprofit and Goldsite which provide results for influenza, respiratory syncytial virus (RSV) and SARS-CoV-2. Between 4 April and 20 October 2023, 1646 patients 6 months and older presenting to an outpatient department of a hospital in Hong Kong with ≥2 symptoms or signs of an acute respiratory illness were enrolled. The point estimates for all three multiplex tests had sensitivity >80% for influenza A and SARS-CoV-2 compared to PCR, and the tests manufactured by Microprofit and Goldsite had sensitivity >84% to detect RSV. Specificity was >97% for all three tests except for the SureScreen test which had specificity 86.2% (95% CI: 83.9% to 88.3%) for influenza A. Sensitivity was lower than reported by the manufacturers, resulting in a higher risk of false negatives. The three multiplex tests performed better in patients with high viral loads.

3.
ASAIO J ; 2024 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-38968145

RESUMEN

Traumatic injury is associated with several pulmonary complications, including pulmonary contusion, transfusion-related acute lung injury (TRALI), and the development of acute respiratory distress syndrome (ARDS). There is a lack of literature on these patients supported with veno-venous extracorporeal oxygenation (VV ECMO). Understanding the safety of using VV ECMO to support trauma patients and the ability to hold anticoagulation is important to broaden utilization. This is a single-center retrospective cohort study of adult trauma patients cannulated for VV ECMO during their initial admission over an 8 year period (2014-2021). We hypothesize that anticoagulation can be held in trauma patients on VV ECMO without increasing mortality or prothrombotic complications. We also describe the coagulopathy of traumatically injured patients on VV ECMO. Withholding anticoagulation was not associated with mortality in our study population, and there were no significant differences in bleeding or clotting complications between patients who did and did not receive systemic anticoagulation. Patients in the nonsurvivor group had increased coagulopathy both pre- and post-cannulation. Our study suggests anticoagulation can be safely withheld in traumatically injured VV ECMO patients without increasing mortality, complication rates, or transfusion requirements. Future, multicenter prospective studies with larger sample sizes are required to confirm our results.

4.
Mov Disord ; 2024 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-38988230

RESUMEN

BACKGROUND: We recently reported an increased risk of Parkinson's disease (PD) in service members who resided at Marine Base Camp Lejeune, North Carolina, when water supplies were contaminated with trichloroethylene and other volatile organic compounds (VOCs). Prior studies suggest that environmental exposures may affect PD phenotype or progression, but this has not been reported for VOCs. OBJECTIVE: The objective of this study was to test whether PD progression is faster in individuals exposed to VOCs in water at Camp Lejeune. METHODS: A cohort of 172,128 marines residing at Camp Lejeune between 1975 and 1985 was previously assembled. We identified individuals with PD in Veterans Health Administration and Medicare databases between 2000 and 2021. Using estimates derived by the US Agency for Toxic Substances and Disease Registry, we classified individuals as exposed or unexposed to VOCs in residential water. We used Kaplan-Meier and Cox regression models to test differences between exposed and unexposed groups in the time from PD diagnosis until psychosis, fracture, fall, or death. RESULTS: Among 270 persons with PD, 177 (65.6%) were exposed to VOCs in residential water. Median cumulative exposure was 4970 µg/L-months, >50-fold the permissible level. Time until psychosis, fracture, and fall were all shorter in the exposed group, with adjusted hazard ratios (HRs) exceeding 2: psychosis HR, 2.19 (95% confidence interval [CI]: 0.99-4.83); fracture HR, 2.44 (95% CI: 0.91-6.55); and fall HR, 2.64 (95% CI: 0.97-7.21). A significant dose response was observed for time to fall (P trend, 0.032). No differences were observed for time until death. CONCLUSIONS: PD progression may be faster in persons exposed to trichloroethylene and other VOCs in water decades earlier. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

6.
Ann Am Thorac Soc ; 2024 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-38996086

RESUMEN

RATIONALE: Sepsis care delivery - including initiation of prompt, appropriate antimicrobials - remains suboptimal. OBJECTIVE: Determine direct and off-target effects of emergency department (ED) sepsis care reorganization. METHODS: This pragmatic pilot trial enrolled adult patients presenting November 2019 to February 2021 to an ED in Utah before and after implementation of a multimodal, team-based "Code Sepsis" protocol. Patients presenting to two other EDs where usual care was continued served as contemporaneous controls. The primary outcome was door-to-antimicrobial time among patients meeting Sepsis-3 criteria before ED departure. Secondary and safety outcomes included all-cause 30-day mortality, antimicrobial utilization and overtreatment, and antimicrobial-associated adverse events. Multivariable regression analyses employed difference-in-differences methods to account for trends in outcomes unrelated to the studied intervention. RESULTS: Code Sepsis protocol activation (N=307) exhibited 8.5% sensitivity and 66% positive predictive value for patients meeting sepsis criteria before ED departure. Among 10,151 patients meeting sepsis criteria during the study, adjusted difference-in-differences analysis demonstrated a 13-minute (95% CI 7-19-minute) decrease in door-to-antimicrobial time associated with Code Sepsis implementation (p<0.001). Mortality and clinical safety outcomes were unchanged, but Code Sepsis implementation was associated with increased false-positive presumptive infection diagnosis among patients meeting sepsis criteria in the ED and increased antimicrobial utilization. CONCLUSIONS: Implementation of a team-based protocol for rapid sepsis evaluation and treatment during the COVID-19 pandemic's first year was associated with decreased ED door-to-antimicrobial time but also increased antimicrobial utilization. Measurement of both patient-centered and off-target effects of sepsis care improvement interventions is essential to comprehensive assessment of their value. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT04148989) This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

7.
J Palliat Med ; 2024 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-39008409
8.
Proc Natl Acad Sci U S A ; 121(29): e2313851121, 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-38976734

RESUMEN

Mass spectrometry-based omics technologies are increasingly used in perturbation studies to map drug effects to biological pathways by identifying significant molecular events. Significance is influenced by fold change and variation of each molecular parameter, but also by multiple testing corrections. While the fold change is largely determined by the biological system, the variation is determined by experimental workflows. Here, it is shown that memory effects of prior subculture can influence the variation of perturbation profiles using the two colon carcinoma cell lines SW480 and HCT116. These memory effects are largely driven by differences in growth states that persist into the perturbation experiment. In SW480 cells, memory effects combined with moderate treatment effects amplify the variation in multiple omics levels, including eicosadomics, proteomics, and phosphoproteomics. With stronger treatment effects, the memory effect was less pronounced, as demonstrated in HCT116 cells. Subculture homogeneity was controlled by real-time monitoring of cell growth. Controlled homogeneous subculture resulted in a perturbation network of 321 causal conjectures based on combined proteomic and phosphoproteomic data, compared to only 58 causal conjectures without controlling subculture homogeneity in SW480 cells. Some cellular responses and regulatory events were identified that extend the mode of action of arsenic trioxide (ATO) only when accounting for these memory effects. Controlled prior subculture led to the finding of a synergistic combination treatment of ATO with the thioredoxin reductase 1 inhibitor auranofin, which may prove useful in the management of NRF2-mediated resistance mechanisms.


Asunto(s)
Proteómica , Humanos , Proteómica/métodos , Línea Celular Tumoral , Células HCT116 , Técnicas de Cultivo de Célula/métodos , Neoplasias del Colon/metabolismo , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/patología , Trióxido de Arsénico/farmacología , Auranofina/farmacología , Proliferación Celular/efectos de los fármacos , Espectrometría de Masas/métodos
9.
Nat Commun ; 15(1): 5710, 2024 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-38977711

RESUMEN

Following Mycobacterium tuberculosis infection, alveolar macrophages are initially infected but ineffectively restrict bacterial replication. The distribution of M. tuberculosis among different cell types in the lung changes with the onset of T cell immunity when the dominant infected cellular niche shifts from alveolar to monocyte-derived macrophages (MDM). We hypothesize that changes in bacterial distribution among different cell types is driven by differences in T cell recognition of infected cells and their subsequent activation of antimicrobial effector mechanisms. We show that CD4 and CD8 T cells efficiently eliminate M. tuberculosis infection in alveolar macrophages, but they have less impact on suppressing infection in MDM, which may be a bacterial niche. Importantly, CD4 T cell responses enhance MDM recruitment to the lung. Thus, the outcome of infection depends on the interaction between the T cell subset and the infected cell; both contribute to the resolution and persistence of the infection.


Asunto(s)
Linfocitos T CD4-Positivos , Linfocitos T CD8-positivos , Pulmón , Macrófagos Alveolares , Ratones Endogámicos C57BL , Mycobacterium tuberculosis , Mycobacterium tuberculosis/inmunología , Mycobacterium tuberculosis/fisiología , Animales , Pulmón/microbiología , Pulmón/inmunología , Pulmón/patología , Macrófagos Alveolares/inmunología , Macrófagos Alveolares/microbiología , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD4-Positivos/inmunología , Ratones , Femenino , Tuberculosis Pulmonar/inmunología , Tuberculosis Pulmonar/microbiología , Tuberculosis Pulmonar/patología , Macrófagos/inmunología , Macrófagos/microbiología , Humanos
10.
Virol J ; 21(1): 153, 2024 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-38972989

RESUMEN

Wild waterfowl serve as a reservoir of some astroviruses. Fecal samples from wild waterfowl collected at Hong Kong's Marshes were tested using pan-astrovirus reverse transcription-PCR. Positive samples underwent subsequent host identification using DNA barcoding. Based on deduced partial sequences, noteworthy samples from three astrovirus groups (mammalian, avian and unclassified astroviruses) were further analyzed by next-generation sequencing. One sample of Avastrovirus 4 clade, MP22-196, had a nearly complete genome identified. The results of ORF2 phylogenetic analysis and genetic distance analysis indicate that Avastrovirus 4 is classified as a distinct subclade within Avastrovirus. MP22-196 has typical astrovirus genome characteristics. The unique characteristics and potential differences of this genome, compared to other avian astrovirus sequences, involve the identification of a modified sgRNA sequence situated near the ORF2 start codon, which precedes the ORF1b stop codon. Additionally, the 3' UTR of MP22-196 is shorter than other avian astroviruses. This study expands our understanding of the Avastrovirus 4 clade.


Asunto(s)
Infecciones por Astroviridae , Aves , Heces , Variación Genética , Genoma Viral , Filogenia , Animales , Hong Kong , Aves/virología , Heces/virología , Infecciones por Astroviridae/veterinaria , Infecciones por Astroviridae/virología , Animales Salvajes/virología , Enfermedades de las Aves/virología , Secuenciación de Nucleótidos de Alto Rendimiento , Avastrovirus/genética , Avastrovirus/clasificación , Avastrovirus/aislamiento & purificación , ARN Viral/genética , Sistemas de Lectura Abierta , Astroviridae/genética , Astroviridae/aislamiento & purificación , Astroviridae/clasificación
11.
Angew Chem Int Ed Engl ; : e202409789, 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-39012726

RESUMEN

The imidophosphorane ligand, [NPtBu3]- (tBu = tert-butyl), enables isolation of a pseudo-tetrahedral, tetravalent praseodymium complex, [Pr4+(NPtBu3)4] (1-Pr), which is characterized by a suite of physical characterization methods including single-crystal X-ray diffraction, electron paramagnetic resonance, and L3-edge X-ray near-edge spectroscopies. Variable-temperature direct-current magnetic susceptibility data, supported by multiconfigurational quantum chemical calculations, demonstrate that the electronic structure diverges from the isoelectronic Ce3+ analogue, driven by increased crystal field. The four-coordinate environment around Pr4+ in 1-Pr, which is unparalleled in reported extended solid systems, provides a unique opportunity to study the interplay between crystal field splitting and spin-orbit coupling in a molecular tetravalent lanthanide within a pseudo-tetrahedral coordination geometry.

12.
iScience ; 27(7): 110220, 2024 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-39036039

RESUMEN

Increasing representation of people with disabilities in science and engineering will require systemic changes to the culture around support and accommodations. Equitable interview practices can help foster such changes. We, an interdisciplinary group of disabled and nondisabled early-career scientists who care deeply about making science more accessible to all, present a framework of suggestions based on Universal Design principles for improving the accessibility and equitability of interviews for people with disabilities and other underrepresented groups. We discuss potential challenges that may arise when implementing these suggestions and provide questions to guide discussions about addressing them.

13.
J Phys Chem Lett ; 15(25): 6544-6549, 2024 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-38885194

RESUMEN

Absorption spectroscopy probing transitions from shallow-core d and f orbitals in lanthanides and actinides reveals information about bonding and the electronic structure in compounds containing these elements. However, spectroscopy in this photon energy range is challenging because of the limited availability of light sources and extremely short penetration depths. In this work, we address these challenges using a tabletop extreme ultraviolet (XUV), ultrafast, laser-driven, high harmonic generation light source, which generates femtosecond pulses in the 40-140 eV range. We present reflection spectroscopy measurements at the N4,5 (i.e., predominantly 4d to 5f transitions) and O4,5 (i.e., 5d to 5f transitions) absorption edges on several lanthanide and uranium oxide crystals. We compare these results to density functional theory calculations to assign the electronic transitions and predict the spectra for other lanthanides. This work paves the way for laboratory-scale XUV absorption experiments for studying crystalline and molecular f-electron systems, with applications ranging from surface chemistry, photochemistry, and electronic or chemical structure determination to nuclear forensics.

14.
medRxiv ; 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38883802

RESUMEN

Background: Assessing COVID-19 vaccine effectiveness (VE) and severity of SARS-CoV-2 variants can inform public health risk assessments and decisions about vaccine composition. BA.2.86 and its descendants, including JN.1 (referred to collectively as "JN lineages"), emerged in late 2023 and exhibited substantial genomic divergence from co-circulating XBB lineages. Methods: We analyzed patients hospitalized with COVID-19-like illness at 26 hospitals in 20 U.S. states admitted October 18, 2023-March 9, 2024. Using a test-negative, case-control design, we estimated the effectiveness of an updated 2023-2024 (Monovalent XBB.1.5) COVID-19 vaccine dose against sequence-confirmed XBB and JN lineage hospitalization using logistic regression. Odds of severe outcomes, including intensive care unit (ICU) admission and invasive mechanical ventilation (IMV) or death, were compared for JN versus XBB lineage hospitalizations using logistic regression. Results: 585 case-patients with XBB lineages, 397 case-patients with JN lineages, and 4,580 control-patients were included. VE in the first 7-89 days after receipt of an updated dose was 54.2% (95% CI = 36.1%-67.1%) against XBB lineage hospitalization and 32.7% (95% CI = 1.9%-53.8%) against JN lineage hospitalization. Odds of ICU admission (adjusted odds ratio [aOR] 0.80; 95% CI = 0.46-1.38) and IMV or death (aOR 0.69; 95% CI = 0.34-1.40) were not significantly different among JN compared to XBB lineage hospitalizations. Conclusions: Updated 2023-2024 COVID-19 vaccination provided protection against both XBB and JN lineage hospitalization, but protection against the latter may be attenuated by immune escape. Clinical severity of JN lineage hospitalizations was not higher relative to XBB lineage hospitalizations.

15.
Front Cell Neurosci ; 18: 1404929, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38903773

RESUMEN

Introduction: Mechanical sensitive channels expressed in mammalian retinas are effectors of elevated pressure stresses, but it is unclear how their activation affects visual function in pressure-related retinal disorders. Methods: This study investigated the role of the transient potential channel vanilloid TRPV4 in photoreceptors and rod bipolar cells (RBCs) with immunohistochemistry, confocal microscopy, electroretinography (ERG), and patch-clamp techniques. Results: TRPV4 immunoreactivity (IR) was found in the outer segments of photoreceptors, dendrites and somas of PKCα-positive RBCs and other BCs, plexiform layers, and retinal ganglion cells (RGCs) in wild-type mice. TRPV4-IR was largely diminished in the retinas of homozygous TRPV4 transgenic mice. Genetically suppressing TRPV4 expression moderately but significantly enhanced the amplitude of ERG a- and b-waves evoked by scotopic and mesopic lights (0.55 to 200 Rh*rod-1 s-1) and photopic lights (105-106 Rh*rod-1 s-1) compared to wild-type mice in fully dark-adapted conditions. The implicit time evoked by dim lights (0.55 to 200 Rh*rod-1 s-1) was significantly decreased for b-waves and elongated for a-waves in the transgenic mice. ERG b-wave evoked by dim lights is primarily mediated by RBCs, and under voltage-clamp conditions, the latency of the light-evoked cation current in RBCs of the transgenic mice was significantly shorter compared to wild-type mice. About 10% of the transgenic mice had one eye undeveloped, and the percentage was significantly higher than in wild-type mice. Conclusions: The data indicates that TRPV4 involves ocular development and is expressed and active in outer retinal neurons, and interventions of TRPV4 can variably affect visual signals in rods, cones, RBCs, and cone ON BCs.

16.
Artículo en Inglés | MEDLINE | ID: mdl-38944197

RESUMEN

BACKGROUND: IgE to galactose-alpha-1,3-galactose (alpha-gal) is linked with tick bites and an important cause of anaphylaxis and urticarial reactions to mammalian meat. The "alpha-gal syndrome" (AGS) is recognized as being common in the southeastern USA, however prevalence studies are lacking and open questions remain about risk factors and clinical presentation of alpha-gal sensitization. OBJECTIVE: Here we characterized the prevalence, as well as presentation and risk factors, of AGS and alpha-gal IgE sensitization in adults in central Virginia recruited without regards to history of allergic disease. METHODS: Adults in central Virginia, primarily University of Virginia Health employees, were recruited as part of a COVID-19 vaccine study. Subjects provided at least one blood sample and answered questionnaires about medical and dietary history. ImmunoCAP was used for IgE assays and ABO blood group was assessed by reverse typing using stored serum. Biobanked serum from COVID-19 patients was also investigated. RESULTS: Of 267 enrollees, median age was 42, 76% were female and 43 (16%) were sensitized to alpha-gal (cut-off 0.1 IU/mL), of which mammalian meat allergy was reported by 7 (2.6%). Sensitized subjects were i) older, ii) had higher total IgE levels but similar frequency of IgE to common respiratory allergens, and iii) were more likely to report tick bites than non-sensitized subjects. Among those who were sensitized, alpha-gal IgE levels were higher among meat allergic than non-allergic subjects (GM 9.0 vs 0.5 IU/mL, P<0.001). Mammalian meat and dairy consumption was common in individuals with low-level sensitization. CONCLUSION: In central Virginia AGS is a dominant cause of adult food allergy with a prevalence approaching or exceeding 2%.

17.
Int J Emerg Med ; 17(1): 76, 2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38898396

RESUMEN

BACKGROUND: Traumatic shock is the leading cause of preventable death with most patients dying within the first six hours from arriving to the hospital. This underscores the importance of prehospital interventions, and growing evidence suggests prehospital transfusion improves survival. Optimizing transfusion triggers in the prehospital setting is key to improving outcomes for patients in hemorrhagic shock. Our objective was to identify factors associated with early in-hospital transfusion requirements available to prehospital clinicians in the field to develop a simple algorithm for prehospital transfusion, particularly for patients with occult shock. METHODS: We included trauma patients transported by a single critical care transport service to a level I trauma center between 2012 and 2019. We used logistic regression, Fast and Frugal Trees (FFTs), and Bayesian analysis to identify factors associated with early in-hospital blood transfusion as a potential trigger for prehospital transfusion. RESULTS: We included 2,157 patients transported from the scene or emergency department (ED) of whom 207 (9.60%) required blood transfusion within four hours of admission. The mean age was 47 (IQR = 28 - 62) and 1,480 (68.6%) patients were male. From 13 clinically relevant factors for early hospital transfusions, four were incorporated into the FFT in following order: 1) SBP, 2) prehospital lactate concentration, 3) Shock Index, 4) AIS of chest (sensitivity = 0.81, specificity = 0.71). The chosen thresholds were similar to conventional ones. Using conventional thresholds resulted in lower model sensitivity. Consistently, prehospital lactate was among most decisive factors of hospital transfusions identified by Bayesian analysis (OR = 2.31; 95% CI 1.55 - 3.37). CONCLUSIONS: Using an ensemble of frequentist statistics, Bayesian analysis and machine learning, we developed a simple, clinically relevant prehospital algorithm to help identify patients requiring transfusion within 4 h of hospital arrival.

19.
PLoS Pathog ; 20(6): e1012333, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38935804

RESUMEN

The bloodstream form of Trypanosoma brucei expresses large poly-N-acetyllactosamine (pNAL) chains on complex N-glycans of a subset of glycoproteins. It has been hypothesised that pNAL may be required for receptor-mediated endocytosis. African trypanosomes contain a unique family of glycosyltransferases, the GT67 family. Two of these, TbGT10 and TbGT8, have been shown to be involved in pNAL biosynthesis in bloodstream form Trypanosoma brucei, raising the possibility that deleting both enzymes simultaneously might abolish pNAL biosynthesis and provide clues to pNAL function and/or essentiality. In this paper, we describe the creation of a TbGT10 null mutant containing a single TbGT8 allele that can be excised upon the addition of rapamycin and, from that, a TbGT10 and TbGT8 double null mutant. These mutants were analysed by lectin blotting, glycopeptide methylation linkage analysis and flow cytometry. The data show that the mutants are defective, but not abrogated, in pNAL synthesis, suggesting that other GT67 family members can compensate to some degree for loss of TbGT10 and TbGT8. Despite there being residual pNAL synthesis in these mutants, certain glycoproteins appear to be particularly affected. These include the lysosomal CBP1B serine carboxypeptidase, cell surface ESAG2 and the ESAG6 subunit of the essential parasite transferrin receptor (TfR). The pNAL deficient TfR in the mutants continued to function normally with respect to protein stability, transferrin binding, receptor mediated endocytosis of transferrin and subcellular localisation. Further the pNAL deficient mutants were as viable as wild type parasites in vitro and in in vivo mouse infection experiments. Although we were able to reproduce the inhibition of transferrin uptake with high concentrations of pNAL structural analogues (N-acetylchito-oligosaccharides), this effect disappeared at lower concentrations that still inhibited tomato lectin uptake, i.e., at concentrations able to outcompete lectin-pNAL binding. Based on these findings, we recommend revision of the pNAL-dependent receptor mediated endocytosis hypothesis.


Asunto(s)
Endocitosis , Glicosiltransferasas , Transferrina , Trypanosoma brucei brucei , Trypanosoma brucei brucei/metabolismo , Trypanosoma brucei brucei/genética , Animales , Endocitosis/fisiología , Ratones , Transferrina/metabolismo , Glicosiltransferasas/metabolismo , Glicosiltransferasas/genética , Tripanosomiasis Africana/parasitología , Tripanosomiasis Africana/metabolismo , Mutación , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genética , Receptores de Transferrina/metabolismo , Receptores de Transferrina/genética , Polisacáridos
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