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1.
Ann Med Surg (Lond) ; 86(6): 3416-3422, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38846811

RESUMO

Background: Albumin acts as a scavenger of reactive oxygen species and an inhibitor of inflammatory processes that underlie hepatic encephalopathy (HE). However, the role of albumin in hepatic encephalopathy is not well-established. The authors performed this meta-analysis to evaluate the efficacy and safety of albumin in the management of hepatic encephalopathy. Methods: The authors carried out an extensive search across multiple databases, including MEDLINE (via PubMed), Embase, CENTRAL, and various trial registries, to identify randomized controlled trials (RCTs) evaluating the impact of albumin administration in HE. The authors used a random-effects model for analyses and presented dichotomous outcomes and continuous outcomes as relative risk and mean difference, along with corresponding 95% CIs, respectively. Heterogeneity was assessed using both the I2 index and χ2 test. Results: Our meta-analysis included 4 RCTs involving 306 patients. Our primary outcomes, mortality, and persistence of HE were reported by all four studies. Albumin was found to significantly decrease mortality in patients with HE [risk ratio (RR) 0.52, 95% CI 0.32-0.83; I2 =0%]. Persistence of HE was found to be comparable between the two groups (RR 0.83, 95% CI 0.68-1.00; I2 =24%). There was no significant difference between the albumin and control groups regarding length of hospital stay (MD -1.55, 95% CI -3.5 to 0.14; I2 =41%), adverse events (RR 1.00, 95% CI 0.87-1.16; I2 =0%), and severe adverse events (RR 0.89, 95% CI 0.59-1.35). Conclusion: Albumin administration in patients with hepatic encephalopathy decreases mortality but does not significantly impact the persistence of HE. Further high-quality, large-scale randomized controlled trials are needed to provide conclusive evidence.

2.
Ann Med Surg (Lond) ; 86(1): 300-307, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38222749

RESUMO

Heart failure (HF) is a widespread clinical condition that affects numerous individuals globally and is a leading cause of hospitalization, particularly in the elderly population. Despite efforts to manage HF using various pharmacological and nonpharmacological interventions, mortality and hospitalization rates remain alarmingly high. Preventive vaccination has emerged as a key measure endorsed by cardiology societies for reducing the morbidity and mortality associated with HF. This study undertakes an extensive review of existing literature to explore the role of vaccination in managing HF, focusing specifically on the immunological pathways involved and potential benefits offered by immunization in this context. This article highlights the role of various vaccines, including influenza, pneumococcal, and COVID-19 vaccines, in reducing HF-related hospitalization, mortality, and overall disease burden. Additionally, this article will delve into specific vaccines that have shown promise in HF management, such as influenza, pneumococcal, and COVID-19 vaccines, along with the rationale for their use, clinical trials, meta-analyses, and real-world data supporting their effectiveness in patients with HF. This article also considers potential challenges and obstacles to widespread vaccination in individuals with HF, which include vaccine hesitancy, accessibility, and adverse events related to vaccines.

4.
Thyroid Res ; 15(1): 22, 2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36464691

RESUMO

BACKGROUND: The debate on whether or not there is a difference in the incidence of thyroid cancer between the patients with Solitary thyroid Nodule (STN) and Multinodular Goiter (MNG) has been constantly present for the last few decades. With newer studies yielding mixed results, it was imperative to systematically compile all available literature on the topic. METHODS: PubMed/MEDLINE, Cochrane Central, ScienceDirect, GoogleScholar, International Clinical Trials registry, and reference lists of the included articles were systematically searched for article retrieval. No filter was applied in terms of time, study design, language or country of publication. Rigorous screening as per PRISMA guidelines was undertaken by 2 independent reviewers in order to identify the articles that were most relevant to the topic. RESULTS: Twenty-two studies spanning from 1992 to 2018 were included in this analysis and encompassed 50,321 patients, 44.2% of which belonged to the STN subgroup and 55.37% to the MNG subgroup. MNG was found to be associated with a significantly lower risk of thyroid cancer (OR = 0.76; 95% CI 0.61-0.96) when compared with STN. Papillary carcinoma was the most frequently occurring carcinoma across both groups, followed by follicular and medullary carcinomas. A subgroup analysis was performed to assess the efficacy of the two most commonly employed diagnostic tools i.e. surgery and fine needle aspiration cytology (FNAC), however it yielded nonsignificant results, indicating a comparable usefulness of the two. Another subgroup analysis run on the basis of the presumed iodine status of the participants also yielded nonsignificant results. CONCLUSION: There is a higher incidence of thyroid cancer among patients of STN, however, given the low quality of existing evidence on the topic, it is crucial to conduct larger studies that can establish association with a greater precision.

5.
Ann Med Surg (Lond) ; 82: 104589, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36268304

RESUMO

Background: Migraine is a primary headache disorder marked by episodes of moderate to severe headache that is unilateral, throbbing in character, having a duration of 4 h to three days, and associated with nausea, vomiting, photophobia, and phonophobia. Aims: Our study aims to determine the frequency of migraine in Pakistan, its association with sociodemographic variables and triggering factors, and the coping mechanisms used. Methods: A cross-sectional study was conducted through an online survey from March 19, 2022, to June 15, 2022. The snowball sampling technique was used for data collection. The questions asked included those on sociodemographic information, screening questions, and questions on triggering factors and coping mechanisms. The screening was done using the ICHD-3 criteria and percentages were calculated using SPSS. Results: Of the 986 respondents, 393 suffered from migraine. The majority of them were female (78.1%), belonged to the age group 20-29 years (69.2%), and were students (76.1%). 32.8% of the migraineurs had a family history of migraine. Most frequent triggers included sleep disturbance (70.5%), stress (66.7%) and fatigue (64.4%). Of the female migraineurs, 31.8% had menstruation as a trigger. The coping mechanisms used included taking rest, medication, staying in a quiet and dark place, and doing massage. Conclusion: The findings suggest that young adults, especially females, with a stressful and sleep-deprived lifestyle are more vulnerable to migraine. However, further studies must focus on trigger synergy and interrelation of triggers that precipitate migraine so a better understanding can be developed for the prevention, diagnosis, and treatment of migraine.

9.
ACS Omega ; 6(46): 31339-31347, 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34841177

RESUMO

The fabrication of active and durable catalysts derived from transition metals is highly desired for the realization of efficient water oxidation reactions. This is particularly important to address the slow oxygen evolution reaction (OER) kinetics and hence can contribute to the conversion and storage of sustainable energy. In this study, the deposition of crystalline flowerlike 2D nanosheets of nickel molybdate (NiMoO4) directly on nickel foam (NF) through an aerosol-assisted chemical vapor deposition process is reported. The NiMoO4 nanosheets were developed on NF by altering the deposition time for 60 and 120 min at a fixed temperature of 480 °C. The structural determination by XRD and XPS analyses revealed a highly crystalline single phase NiMoO4. The micrographs of NiMoO4 show that the surface consisted of vertically aligned 2D nanosheets assembled into flowerlike structures. The nanosheets produced after 60 min deposition time on a network of NF is found to perform better for OER as compared to the one developed for 120 min. A reference current density of 10 mA cm-2 was achieved at an overpotential (η) of 320 mV, which was better as compared to that reported for the benchmark OER catalyst in 1.0 M KOH. Moreover, a small Tafel value (75 mV dec-1) and good OER stability for >15 h were also observed.

10.
Anal Methods ; 13(36): 4019-4037, 2021 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-34555136

RESUMO

The emergence of a pandemic scale respiratory illness (COVID-19: coronavirus disease 2019) and the lack of the world's readiness to prevent its spread resulted in an unprecedented rise of biomedical diagnostic industries, as they took lead to provide efficient diagnostic solutions for COVID-19. However, these circumstances also led to numerous emergency use authorizations without appropriate evaluation that compromised standards, which could result in a larger than usual number of false-positive or false-negative results, leading to unwanted ambiguity in already confusing realities of the pandemic-hit closures of the world economy. This review is aimed at comparing the claimed or reported clinical sensitivity and clinical specificity of commercially available rapid antibody diagnostics with independently evaluated clinical performance results of the tests. Thereby, we not only present the types of modern antibody diagnostics and their working principles but summarize their experimental evaluations and observed clinical efficiencies to highlight the research, development, and commercialization issues with future challenges. Still, it must be emphasized that the serological or antibody tests do not serve the purpose of early diagnosis but are more suitable for epidemiology and screening populaces with an active immune response, recognizing convalescent plasma donors, and determining vaccine efficacy.


Assuntos
COVID-19 , SARS-CoV-2 , Imunidade Adaptativa , COVID-19/terapia , Humanos , Imunização Passiva , Sensibilidade e Especificidade , Soroterapia para COVID-19
11.
Parasit Vectors ; 14(1): 283, 2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-34039408

RESUMO

BACKGROUND: The proliferative stage (tachyzoite) of Toxoplasma gondii (T. gondii) is critical for its transmission and pathogenesis, and a proto-oncogene eukaryotic translation initiation factor (eIF-5A) plays an important role in various cellular processes such as cell multiplication. METHODS: We performed a proteomic study to evaluate the specific roles of eIF-5A involved in invasion and replication of T. gondii, and both in vivo and in vitro trials using eIF-5A-interfered and wild tachyzoites were performed to verify the proteomic results. RESULTS: The results of our study showed that T. gondii eIF-5A affected tachyzoite growth and also participated in the synthesis of proteins through regulation of both ribosomal and splicing pathways. Inhibition of eIF-5A in T. gondii resulted in the downregulated expression of soluble adhesions, such as microneme protein 1 (MIC1) and MIC4, which in turn decreased the parasite population that adhered to the surface of host cells. The reduced attachment, combined with lower expression of some rhoptry proteins (ROPs) and dense granule antigens (GRAs) involved in different stages of T. gondii invasion such as ROP4 and GRA3, ultimately reduce the invasion efficiency. These processes regulated by eIF-5A eventually affect the replication of tachyzoites. CONCLUSIONS: Our findings showed that eIF-5A influenced tachyzoite survival and was also involved in the process of parasite invasion and replication. These results will provide new clues for further development of targeted drugs to control T. gondii infection.


Assuntos
Fatores de Iniciação de Peptídeos/genética , Fatores de Iniciação de Peptídeos/metabolismo , Proteômica/métodos , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Toxoplasma/genética , Toxoplasma/fisiologia , Animais , Sistemas CRISPR-Cas , Replicação do DNA , Feminino , Deleção de Genes , Camundongos Endogâmicos BALB C , Mapas de Interação de Proteínas , Proto-Oncogenes/genética , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Ratos , Ratos Sprague-Dawley , Toxoplasmose/parasitologia , Virulência , Fator de Iniciação de Tradução Eucariótico 5A
12.
Parasit Vectors ; 14(1): 276, 2021 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-34022913

RESUMO

BACKGROUND: The liver fluke Fasciola gigantica secretes excretory-secretory proteins during infection to mediate its interaction with the host. In this study, we investigated the immunomodulatory effects of a recombinant tegumental calcium-binding EF-hand protein 4 of F. gigantica (rFg-CaBP4) on goat monocytes. METHODS: The rFg-CaBP4 protein was induced and purified by affinity chromatography. The immunogenic reaction of rFg-CaBP4 against specific antibodies was detected through western blot analysis. The binding of rFg-CaBP4 on surface of goat monocytes was visualized by immunofluorescence assay. The localization of CaBP4 within adult fluke structure was detected by immunohistochemical analysis. The cytokine transcription levels in response to rFg-CaBP4 were examined using ABI 7500 real-time PCR system. The expression of the major histocompatibility complex (MHC) class-II molecule (MHC-II) in response to rFg-CaBP4 protein was analyzed using Flow cytometry. RESULTS: The isopropyl-ß-D-thiogalactopyranoside-induced rFg-CaBP4 protein reacted with rat sera containing anti-rFg-CaBP4 polyclonal antibodies in a western blot analysis. The adhesion of rFg-CaBP4 to monocytes was visualized by immunofluorescence and laser scanning confocal microscopy. Immunohistochemical analysis localized native CaBP4 to the oral sucker, pharynx, genital pore, acetabulum and tegument of adult F. gigantica. Co-incubation of rFg-CaBP4 with concanavalin A-stimulated monocytes increased the transcription levels of interleukin (IL)-2, IL-4, interferon gamma and transforming growth factor-ß. However, a reduction in the expression of IL-10 and no change in the expression of tumor necrosis factor-α were detected. Additionally, rFg-CaBP4-treated monocytes exhibited a marked increase in the expression of the major histocompatibility complex (MHC) class-II molecule (MHC-II) and a decrease in MHC-I expression, in a dose-dependent manner. CONCLUSIONS: These findings provide additional evidence that calcium-binding EF-hand proteins play roles in host-parasite interaction. Further characterization of the immunomodulatory role of rFg-CaBP4 should expand our understanding of the strategies used by F. gigantica to evade the host immune responses.


Assuntos
Proteínas de Ligação ao Cálcio/imunologia , Fasciola/química , Fasciola/imunologia , Imunomodulação , Monócitos/imunologia , Animais , Proteínas de Ligação ao Cálcio/farmacologia , Citocinas/genética , Citocinas/imunologia , Fasciola/genética , Fasciolíase/parasitologia , Cabras/imunologia , Monócitos/efeitos dos fármacos , Proteínas Recombinantes/farmacologia
13.
Analyst ; 146(10): 3317-3327, 2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-33999084

RESUMO

Herein, we report the fabrication of NiO-CoO films for the electrochemical detection of hydrazine. An electrochemical sensor was devised where aerosol assisted chemical vapor deposition (AACVD) was employed as a nifty method for synthesizing NiO-CoO films over FTO electrodes. NiO-CoO-nanoparticle (NP) and NiO-CoO-nanowall (NW) films were fabricated over FTO substrates. The electrocatalytic analysis was performed in a standard three-electrode electrochemical setup. NiO-CoO-NW/FTO showed enhanced electro-oxidation for hydrazine at all concentrations tested. XRD, XPS, EDX, and FE-SEM techniques were used to characterize the structural, morphological, and elemental properties of NiO-CoO films. The results showed improved sensitivity, a large dynamic range, and good long-term stability of NiO-CoO-NW films. The amperometric response was used to measure the detection limit, and it was as low as 0.01 µM, and the sensitivity is ∼33 µA µM-1 cm-2. Besides, the NiO-CoO-NW/FTO electrodes showed significant selectivity towards hydrazine upon testing cross-sensitivity to other common interfering molecules. This strategy of using NiO-CoO-NW/FTO electrodes prepared via AACVD has great potential for the direct determination of hydrazine in environmental sensing applications.

14.
Nanomaterials (Basel) ; 11(5)2021 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-33923371

RESUMO

This research aims to synthesize the Bis(di-isobutyldithiophosphinato) nickel (II) complex [Ni(iBu2PS2)] to be employed as a substrate for the deposition of nickel sulfide nanostructures, and to investigate its dielectric and impedance characteristics for applications in the electronic industry. Various analytical tools including elemental analysis, mass spectrometry, IR, and TGA were also used to further confirm the successful synthesis of the precursor. NiS nanostructures were grown on the glass substrates by employing an aerosol assisted chemical vapor deposition (AACVD) technique via successful decomposition of the synthesized complex under variable temperature conditions. XRD, SEM, TEM, and EDX methods were well applied to examine resultant nanostructures. Dielectric studies of NiS were carried out at room temperature within the 100 Hz to 5 MHz frequency range. Maxwell-Wagner model gave a complete explanation of the variation of dielectric properties along with frequency. The reason behind high dielectric constant values at low frequency was further endorsed by Koops phenomenological model. The efficient translational hopping and futile reorientation vibration caused the overdue exceptional drift of ac conductivity (σac) along with the rise in frequency. Two relaxation processes caused by grains and grain boundaries were identified from the fitting of a complex impedance plot with an equivalent circuit model (Rg Cg) (Rgb Qgb Cgb). Asymmetry and depression in the semicircle having center present lower than the impedance real axis gave solid justification of dielectric behavior that is non-Debye in nature.

15.
Sensors (Basel) ; 21(3)2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33530518

RESUMO

With worldwide deployment of LoRa/LoRaWAN LPWAN networks in a large variety of applications, it is crucial to improve the robustness of LoRa channel access which is largely ALOHA-like to support environments with higher node density. This article presents extensive experiments on LoRa Channel Activity Detection and Capture Effect property in order to better understand how a competition-based channel access mechanisms can be optimized for LoRa LPWAN radio technology. In the light of these experimentation results, the contribution continues by identifying design guidelines for a channel access mechanism in LoRa and by proposing a channel access method with a lightweight collision avoidance mechanism that can operate without a reliable Clear Channel Assessment procedure. The proposed channel access mechanism has been implemented and preliminary tests show promising capabilities in increasing the Packet Delivery Rate in dense configurations.

16.
Vaccines (Basel) ; 8(4)2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-33276581

RESUMO

ADP-ribosylation factor 1 (HcARF1) is one of the Haemonchus contortus (H. contortus) excretory/secretory proteins involved in modulating the immune response of goat peripheral blood mononuclear cells (PBMC). Here, we evaluated the immunogenic potential of recombinant HcARF1 (rHcARF1) against H. contortus infection in Institute of Cancer Research (ICR) mice. Briefly, rHcARF1 was entrapped in poly (D, L-lactide-co-glycolide) (PLGA) and chitosan (CS) nanoparticles (NP) and injected into mice as a vaccine. Fifty-six ICR mice were assigned randomly into seven groups, with eight animals in each group, and they were vaccinated subcutaneously. At the end of the experiment (14th day), the blood and the spleen were collected from euthanized mice to detect lymphocyte proliferation, cytokine analysis, and the production of antigen-specific antibodies. Scanning electron microscope was used to determine the size, morphology, and zeta potential of nanoparticles. Flow cytometry was performed, which presented the increase percentages of CD4+ T cells (CD3e+CD4+), CD8+ T cells (CD3e+CD8+) and dendritic cells (CD11c+CD83+, CD11c+CD86+) in mice vaccinated with rHcARF1+PLGA NP. Immunoassay analysis show raised humoral (Immunoglobulin (Ig)G1, IgG2a, IgM) and cell-mediated immune response (Interleukin (IL)-4, IL-12, and IL-17, and Interferon (IFN)-γ) induced by rHcARF1+PLGA NP. Experimental groups that were treated with the antigen-loaded NP yield higher lymphocyte proliferation than the control groups. Based on these results, we could propose that the rHcARF1 encapsulated in NP could stimulate a strong immune response in mice rather than administering alone against the infection of H. contortus.

17.
Anal Methods ; 12(32): 4028-4036, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32744279

RESUMO

Fluorine doped tin oxide (FTO) substrates were deposited with thin metallic nickel films, having distinguishable surface morphologies, via a rapid, facile, and scalable approach i.e., aerosol assisted chemical vapor deposition (AACVD). The growth patterns of the nickel deposits were studied, showing a coalescing behavior as a function of the deposition time in a hierarchical fashion. These studies were followed by electrochemical measurements to design an efficient sensor for formaldehyde detection. The electrochemical responses were correlated with the surface characteristics of the films, whereas the optimized parameters were subjected to the evaluation of sensing performances. The developed sensor demonstrated a detection limit of 8.3 × 10-6 M and a sensitivity of 0.18 A M-1 within a linear range of 0-6.5 mM. Further, the sensor showed a response time of less than 5 s, selectivity against similar concentrations of methanol and formaldehyde, and recovery of ∼102% in a spiked fruit juice sample. Finally, the commercial viability of the fabrication procedure is tested using batch production analysis, and the high reproducibility of the data shows a promising future in mass production. It is envisaged that such low-cost fabrication procedures can be converted into many useful applications in the future.

18.
Acta Trop ; 209: 105552, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32485167

RESUMO

Insulin signaling pathway is an ancient and highly conserved pathway known to play critical roles in cell growth, control and metabolic regulation. In this study, we identified and characterized two insulin receptor genes (TsIR-1316 and TsIR-4810) from Taenia solium. TsIR-1316 was grouped with E. multilocularis insulin receptor (EmIR-1) and TsIR-4810 was closer to Taenia pisiformis insulin-like growth factor receptor (TpIR) on the same branch with a very high bootstrap value. TsIR-1316 was located on the integument of larvae and adult worms, as well as the ovary of adults and eggs. Alternatively, TsIR-4810 was located in the parenchyma and reproductive organs of the adult worms. By using in vitro cultivation systems with Cysticercus pisiformis as a model, we demonstrated that anti-TsIRs-LBD antibodies could effectively block the insulin signaling pathway, resulting in reduced phosphorylation of the insulin receptor as well as lower levels of glucose uptake and glycogen synthesis. The rabbits immunized with TsIR-1316-LBD, TsIR-4810-LBD and TsIR-1316-LBD + TsIR-4810-LBD produced protection against infection of T. pisiformis as demonstrated by a 94.6%, 96% and 80% reduction of establishment of larvae, respectively. These data suggested that TsIR-1316-LBD and TsIR-4810-LBD are promising vaccine candidates or novel drug targets against swine cysticercosis.


Assuntos
Cisticercose/prevenção & controle , Receptor de Insulina/imunologia , Taenia solium/imunologia , Vacinas/imunologia , Animais , Cisticercose/tratamento farmacológico , Feminino , Coelhos , Receptor de Insulina/antagonistas & inibidores , Receptor de Insulina/genética , Receptor de Insulina/fisiologia , Suínos , Doenças dos Suínos/prevenção & controle
19.
Dalton Trans ; 49(22): 7355-7363, 2020 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-32432621

RESUMO

Ovarian cancer is a highly aggressive disease which is treated by surgery and platinum chemotherapy. However, a significant proportion of treated patients develop resistance to platinum treatment resulting in tumor relapse. Acquired platinum resistance has been recently correlated with activation of pro-survival endoplasmic reticulum (ER) stress responses. We hypothesized that Au complexes that induce severe ER stress might counteract pro-survival cellular attempts leading to the ER stress-mediated apoptosis and reduced platinum resistance. In this work, we prepared a series of highly cytotoxic AuI-dialkyldithiocarbamate complexes and investigated their anticancer potential in ovarian cancer cells. Complexes demonstrated surprisingly low stability in chloroform, resulting in the formation of an Au chain polymer, which also displayed excellent cytotoxicity. Lead complex 2 induced oxidative stress and ER stress-mediated p53-independent apoptosis associated with PARP cleavage and cell cycle arrest at G2/M phase. Importantly, 2 caused the surface exposure of calreticulin (CRT), which is the first step in the activation of cellular immunogenic response.


Assuntos
Antineoplásicos/farmacologia , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Estresse do Retículo Endoplasmático/imunologia , Compostos Organoáuricos/farmacologia , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/imunologia , Fosfinas/farmacologia , Tiocarbamatos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Estrutura Molecular , Compostos Organoáuricos/síntese química , Compostos Organoáuricos/química , Neoplasias Ovarianas/patologia , Estresse Oxidativo/efeitos dos fármacos , Fosfinas/química , Tiocarbamatos/química , Células Tumorais Cultivadas
20.
Elife ; 92020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32267234

RESUMO

Human epidermal growth factor receptors (HERs) are the primary targets of many directed cancer therapies. However, the reason a specific dimer of HERs generates a stronger proliferative signal than other permutations remains unclear. Here, we used single-molecule immunoprecipitation to develop a biochemical assay for endogenously-formed, entire HER2-HER3 heterodimers. We observed unexpected, large conformational fluctuations in juxta-membrane and kinase domains of the HER2-HER3 heterodimer. Nevertheless, the individual HER2-HER3 heterodimers catalyze tyrosine phosphorylation at an unusually high rate, while simultaneously interacting with multiple copies of downstream signaling effectors. Our results suggest that the high catalytic rate and multi-tasking capability make a concerted contribution to the strong signaling potency of the HER2-HER3 heterodimers.


Assuntos
Receptor ErbB-2/química , Receptor ErbB-2/metabolismo , Receptor ErbB-3/química , Receptor ErbB-3/metabolismo , Transdução de Sinais , Dimerização , Células HEK293 , Humanos , Modelos Moleculares , Fosforilação , Conformação Proteica , Domínios Proteicos , Receptor ErbB-2/genética , Receptor ErbB-3/genética , Imagem Individual de Molécula , Tirosina/metabolismo
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