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1.
Hong Kong Med J ; 30(4): 271-280, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39049143

RESUMEN

INTRODUCTION: This study reviewed the diagnostic accuracy of the prehospital electrocardiogram (PHECG) rule-based algorithm for ST-elevation myocardial infarction (STEMI) universally utilised in Hong Kong. METHODS: This prospective observational study was linked to a population-wide project. We analysed 2210 PHECGs performed on patients who presented to the emergency medical service (EMS) with chest pain from 1 October to 31 December 2021. The diagnostic accuracy of the adopted rulebased algorithm, the Hannover Electrocardiogram System, was evaluated using the adjudicated blinded rating by two investigators as the primary reference standard. Diagnostic accuracy was also evaluated using the attending emergency physician's diagnosis and the diagnosis on hospital discharge as secondary reference standards. RESULTS: The prevalence of STEMI was 5.1% (95% confidence interval [CI]=4.2%-6.1%). Using the adjudicated blinded rating by investigators as the reference standard, the rule-based PHECG algorithm had a sensitivity of 94.6% (95% CI=88.2%-97.8%), specificity of 87.9% (95% CI=86.4%-89.2%), positive predictive value of 29.4% (95% CI=24.8%-34.4%), and negative predictive value of 99.7% (95% CI=99.3%-99.9%) [all P<0.05]. CONCLUSION: The rule-based PHECG algorithm that is widely used in Hong Kong demonstrated high sensitivity and fair specificity for the diagnosis of STEMI.


Asunto(s)
Algoritmos , Electrocardiografía , Servicios Médicos de Urgencia , Infarto del Miocardio con Elevación del ST , Sensibilidad y Especificidad , Humanos , Electrocardiografía/métodos , Estudios Prospectivos , Servicios Médicos de Urgencia/métodos , Hong Kong , Infarto del Miocardio con Elevación del ST/diagnóstico , Masculino , Femenino , Persona de Mediana Edad , Anciano , Dolor en el Pecho/etiología , Dolor en el Pecho/diagnóstico , Prevalencia
2.
Front Med (Lausanne) ; 10: 1162808, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37521348

RESUMEN

We independently analyzed two large public domain datasets that contain 1H-NMR spectral data from lung cancer and sex studies. The biobanks were sourced from the Karlsruhe Metabolomics and Nutrition (KarMeN) study and Bayesian Automated Metabolite Analyzer for NMR data (BATMAN) study. Our approach of applying novel artificial intelligence (AI)-based algorithms to NMR is an attempt to globalize metabolomics and demonstrate its clinical applications. The intention of this study was to analyze the resulting spectra in the biobanks via AI application to demonstrate its clinical applications. This technique enables metabolite mapping in areas of localized enrichment as a measure of true activity while also allowing for the accurate categorization of phenotypes.

3.
Pulm Circ ; 12(3): e12103, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35911185

RESUMEN

The spectrum of patients referred for suspected pulmonary arterial hypertension (PAH) includes a population with clinical features suggestive of pulmonary hypertension due to left heart disease (PH-LHD). Even after right heart catheterization (RHC) performed at rest, it can be a challenge to identify patients who will clearly benefit from PAH drug therapy. Therefore, the objective of this study was to evaluate the role of exercise RHC to influence decisions regarding prescription of PAH drug therapy in this population. A retrospective cohort study was conducted of older adults with risk factors for PH-LHD and suspected PH referred for exercise RHC. One year follow-up was conducted to record clinical outcomes, all changes in PAH drug therapy, and changes in patient-reported quality of life. The final cohort included 61 patients, mean age of 69 ± 10; 44% and 34% had a history of coronary artery disease and atrial fibrillation respectively. Exercise changed the proportional breakdown of hemodynamic diagnoses from 36% No PH, 44% PAH, and 20% PH-LHD at rest to 15% No PH, 36% PAH, and 49% PH-LHD. Although a significant proportion of patients were reclassified as PH-LHD, there was an overall increase in the proportion of patients receiving PAH drug therapy, particularly for those with PAH confirmed by exercise RHC. A total of 11 PAH drug prescriptions were employed before exercise RHC increasing to 24 after (p = 0.002). Patients receiving PAH therapy demonstrated significant improvement in self-reported quality of life. Exercise RHC appeared to influence selection of PAH drug therapy.

4.
Methods Mol Biol ; 2370: 169-183, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34611869

RESUMEN

The aggregation of therapeutic antibodies is a major issue for the pharmaceutical industry leading to loss of drug quality, increased dosage, and unwanted immune responses such as the production of anti-drug antibodies (ADA). As aggregation can occur at various stages of development and storage, much work has been performed to reduce or eliminate it. In this report we analyzed four antibodies available in the PDB (1IGT, 1IGY, 1HZH, and 5DK3) using the online software UCSF Chimera to study the structural features of the proteins and the associated N-linked glycans in the CH2 domains of the Fc region. To study antibody aggregation in silico we used the online software TANGO and AGGRESCAN to identify aggregation prone regions (APR) in the antibodies and the influence of the Fc glycans on hydrophobic and aromatic residues present in the APRs. In the 3D structures of 1IGT and 1IGY the glycan chains are in close enough proximity to influence and protect these hydrophobic regions. However, in the 3D structures of 1HZH and 5DK3 the glycans do not appear to influence the likely APRs of the antibodies. Therefore, in these structures we modified the Fc glycan regions by adjusting the glycosylated asparagine side chains and glycosidic bonds. We successfully adjusted the glycan chains of 1HZH and 5DK3 and reduced the distance between them and the APRs to show potential influence on aggregation. However, similar to 5DK3, the influence of glycosylation on the APRs of the antibody was limited due to the size of the glycans present in the 3D structure. This report is based on in silico studies to show how antibody glycans can influence aggregation.


Asunto(s)
Glicosilación , Anticuerpos Monoclonales/metabolismo , Interacciones Hidrofóbicas e Hidrofílicas , Fragmentos Fc de Inmunoglobulinas/metabolismo , Polisacáridos
5.
Artículo en Inglés | WPRIM (Pacífico Occidental) | ID: wpr-929144

RESUMEN

Bacterial infection is a common finding in patients, who develop medication-related osteonecrosis of the jaw (MRONJ) by the long-term and/or high-dose use of anti-resorptive agents such as bisphosphonate (BPs). However, pathological role of bacteria in MRONJ development at the early stage remains controversial. Here, we demonstrated that commensal microbiota protects against MRONJ development in the pulp-exposed periapical periodontitis mouse model. C57/BL6 female mice were treated with intragastric broad-spectrum antibiotics for 1 week. Zoledronic acid (ZOL) through intravenous injection and antibiotics in drinking water were administered for throughout the experiment. Pulp was exposed on the left maxillary first molar, then the mice were left for 5 weeks after which bilateral maxillary first molar was extracted and mice were left for additional 3 weeks to heal. All mice were harvested, and cecum, maxilla, and femurs were collected. ONJ development was assessed using μCT and histologic analyses. When antibiotic was treated in mice, these mice had no weight changes, but developed significantly enlarged ceca compared to the control group (CTL mice). Periapical bone resorption prior to the tooth extraction was similarly prevented when treated with antibiotics, which was confirmed by decreased osteoclasts and inflammation. ZOL treatment with pulp exposure significantly increased bone necrosis as determined by empty lacunae and necrotic bone amount. Furthermore, antibiotics treatment could further exacerbate bone necrosis, with increased osteoclast number. Our findings suggest that the commensal microbiome may play protective role, rather than pathological role, in the early stages of MRONJ development.


Asunto(s)
Animales , Femenino , Humanos , Ratones , Osteonecrosis de los Maxilares Asociada a Difosfonatos/prevención & control , Conservadores de la Densidad Ósea , Difosfonatos , Microbiota , Enfermedades Periapicales , Ácido Zoledrónico
6.
Clin Oncol (R Coll Radiol) ; 34(4): e160-e167, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-34772581

RESUMEN

AIMS: Hearing loss is a common debilitating complication in nasopharyngeal carcinoma (NPC) survivors. The aim of the present study was to investigate the impact of inner ear/cochlear radiation dose and cisplatin use on early and late sensorineural hearing loss (SNHL) in NPC patients treated with radiotherapy alone, concurrent chemoradiation (cCRT) and induction chemotherapy followed by cCRT (iCRT) in the intensity-modulated radiotherapy era. MATERIALS AND METHODS: The study included 81 NPC patients treated with intensity-modulated radiotherapy between 2014 and 2016. Pure tone audiometry was carried out at baseline and follow-up. The effects of cochlear/inner ear radiation and cisplatin doses on early (<12 months) and late (≥24 months) SNHL were analysed using multivariable regression after adjusting for important predictors. RESULTS: In total, 156 ears were examined. In early SNHL (n = 136), cisplatin use predicted the incidence of early high-frequency SHNL (HF-SNHL) (odds ratio 6.4, 95% confidence interval 1.7-23.9, P = 0.005). Ninety ears were analysed for late SNHL (median follow-up 38 months). Inner ear/cochlear radiation and cisplatin doses and better pre-treatment hearing were independent predictors of threshold change at 4 kHz. Every 10 Gy increase in inner ear/cochlear Dmean resulted in 5-dB and 6-dB threshold changes, respectively (cochlear Dmean: B = 0.005, 95% confidence interval 0.0004-0.009, P = 0.031; inner ear Dmean: B = 0.006, 95% confidence interval 0.001-0.010, P = 0.014). Cisplatin use was associated with late HF-SNHL (odds ratio 3.74, 95% confidence interval 1.1-12.3, P = 0.031). In the cCRT and iCRT subgroups, no cisplatin dose-dependent ototoxicity was observed. Severe (≥30 dB) late HF-SNHL occurred in 14% and 25% of the patients when the cochlear dose constraints were 40 Gy and 44 Gy, respectively. The radiotherapy-alone group did not develop severe late HF-SNHL. CONCLUSION: Cochlear/inner ear radiation dose and cisplatin use showed differential and independent ototoxicity in early and late SNHL. As cochlear/inner ear dose-dependent ototoxicity was demonstrated, the cochlear dose constraint should be as low as reasonably achievable, especially when cisplatin is also administered.


Asunto(s)
Pérdida Auditiva Sensorineural , Neoplasias Nasofaríngeas , Ototoxicidad , Cisplatino , Terapia Combinada , Pérdida Auditiva Sensorineural/inducido químicamente , Pérdida Auditiva Sensorineural/epidemiología , Humanos , Carcinoma Nasofaríngeo/radioterapia , Neoplasias Nasofaríngeas/tratamiento farmacológico , Neoplasias Nasofaríngeas/radioterapia , Sobrevivientes
7.
Mol Cell Oncol ; 8(5): 1974278, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34859140

RESUMEN

The protein-lipid complex alpha1-oleate, derived from HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells), is identified as a molecular entity with significant therapeutic potential. Structural characterization of the complex and results of a successful placebo-controlled clinical trial are presented.

8.
Sci Rep ; 11(1): 14069, 2021 07 07.
Artículo en Inglés | MEDLINE | ID: mdl-34234213

RESUMEN

CD44 is emerging as an important receptor biomarker for various cancers. Amongst these is oral cancer, where surgical resection remains an essential mode of treatment. Unfortunately, surgery is frequently associated with permanent disfigurement, malnutrition, and functional comorbidities due to the difficultly of tumour removal. Optical imaging agents that can guide tumour tissue identification represent an attractive approach to minimising the impact of surgery. Here, we report the synthesis of a water-soluble fluorescent probe, namely HA-FA-HEG-OE (compound 1), that comprises components originating from natural sources: oleic acid, ferulic acid and hyaluronic acid. Compound 1 was found to be non-toxic, displayed aggregation induced emission and accumulated intracellularly in vesicles in SCC-9 oral squamous cells. The uptake of 1 was fully reversible over time. Internalization of compound 1 occurs through receptor mediated endocytosis; uniquely mediated through the CD44 receptor. Uptake is related to tumorigenic potential, with non-tumorigenic, dysplastic DOK cells and poorly tumorigenic MCF-7 cells showing only low intracellular levels and highlighting the critical role of endocytosis in cancer progression and metastasis. Together, the recognised importance of CD44 as a cancer stem cell marker in oral cancer, and the reversible, non-toxic nature of 1, makes it a promising agent for real time intraoperative imaging.


Asunto(s)
Productos Biológicos , Portadores de Fármacos , Colorantes Fluorescentes/administración & dosificación , Imagen Molecular/métodos , Neoplasias de la Boca/diagnóstico por imagen , Supervivencia Celular/efectos de los fármacos , Ácidos Cumáricos/química , Colorantes Fluorescentes/síntesis química , Colorantes Fluorescentes/química , Humanos , Ácido Hialurónico/química , Estructura Molecular , Neoplasias de la Boca/metabolismo , Imagen Óptica/métodos , Análisis Espectral
9.
Nat Commun ; 12(1): 3427, 2021 06 08.
Artículo en Inglés | MEDLINE | ID: mdl-34103518

RESUMEN

Partially unfolded alpha-lactalbumin forms the oleic acid complex HAMLET, with potent tumoricidal activity. Here we define a peptide-based molecular approach for targeting and killing tumor cells, and evidence of its clinical potential (ClinicalTrials.gov NCT03560479). A 39-residue alpha-helical peptide from alpha-lactalbumin is shown to gain lethality for tumor cells by forming oleic acid complexes (alpha1-oleate). Nuclear magnetic resonance measurements and computational simulations reveal a lipid core surrounded by conformationally fluid, alpha-helical peptide motifs. In a single center, placebo controlled, double blinded Phase I/II interventional clinical trial of non-muscle invasive bladder cancer, all primary end points of safety and efficacy of alpha1-oleate treatment are reached, as evaluated in an interim analysis. Intra-vesical instillations of alpha1-oleate triggers massive shedding of tumor cells and the tumor size is reduced but no drug-related side effects are detected (primary endpoints). Shed cells contain alpha1-oleate, treated tumors show evidence of apoptosis and the expression of cancer-related genes is inhibited (secondary endpoints). The results are especially encouraging for bladder cancer, where therapeutic failures and high recurrence rates create a great, unmet medical need.


Asunto(s)
Péptidos/química , Péptidos/uso terapéutico , Neoplasias de la Vejiga Urinaria/tratamiento farmacológico , Secuencia de Aminoácidos , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Endocitosis/efectos de los fármacos , Determinación de Punto Final , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Ácidos Oléicos/química , Péptidos/farmacología , Placebos , Conformación Proteica , Espectroscopía de Protones por Resonancia Magnética , Termodinámica , Neoplasias de la Vejiga Urinaria/genética , Neoplasias de la Vejiga Urinaria/patología
11.
Biomolecules ; 10(3)2020 03 10.
Artículo en Inglés | MEDLINE | ID: mdl-32164323

RESUMEN

Elucidating the structural details of proteins is highly valuable and important for the proper understanding of protein function. In the case of intrinsically disordered proteins (IDPs), however, obtaining the structural details is quite challenging, as the traditional structural biology tools have only limited use. Nuclear magnetic resonance (NMR) is a unique experimental tool that provides ensemble conformations of IDPs at atomic resolution, and when studying IDPs, a slightly different experimental strategy needs to be employed than the one used for globular proteins. We address this point by reviewing many NMR investigations carried out on the α-synuclein protein, the aggregation of which is strongly correlated with Parkinson's disease.


Asunto(s)
Agregado de Proteínas , alfa-Sinucleína/química , Humanos , Resonancia Magnética Nuclear Biomolecular , Enfermedad de Parkinson/metabolismo , Estructura Secundaria de Proteína , alfa-Sinucleína/metabolismo
12.
Artículo en Inglés | WPRIM (Pacífico Occidental) | ID: wpr-781379

RESUMEN

High-risk human papillomaviruses (HPVs) are involved in the development of several human cancers, including oropharyngeal squamous cell carcinomas. However, many studies have demonstrated that HPV alone is not sufficient for the oncogenic transformation of normal human epithelial cells, indicating that additional cofactors are required for the oncogenic conversion of HPV-infected cells. Inasmuch as chronic inflammation is also closely associated with carcinogenesis, we investigated the effect of chronic exposure to tumor necrosis factor α (TNFα), the major proinflammatory cytokine, on oncogenesis in two immortalized oral keratinocyte cell lines, namely, HPV16-immortalized and human telomerase reverse transcriptase (hTERT)-immortalized cells. TNFα treatment led to the acquisition of malignant growth properties in HPV16-immortalized cells, such as (1) calcium resistance, (2) anchorage independence, and (3) increased cell proliferation in vivo. Moreover, TNFα increased the cancer stem cell-like population and stemness phenotype in HPV16-immortalized cells. However, such transforming effects were not observed in hTERT-immortalized cells, suggesting an HPV-specific role in TNFα-promoted oncogenesis. We also generated hTERT-immortalized cells that express HPV16 E6 and E7. Chronic TNFα exposure successfully induced the malignant growth and stemness phenotype in the E6-expressing cells but not in the control and E7-expressing cells. We further demonstrated that HPV16 E6 played a key role in TNFα-induced cancer stemness via suppression of the stemness-inhibiting microRNAs miR-203 and miR-200c. Overexpression of miR-203 and miR-200c suppressed cancer stemness in TNFα-treated HPV16-immortalized cells. Overall, our study suggests that chronic inflammation promotes cancer stemness in HPV-infected cells, thereby promoting HPV-associated oral carcinogenesis.

13.
Methods Mol Biol ; 2039: 173-183, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31342427

RESUMEN

Diffusion-ordered spectroscopy (DOSY) is a widely used NMR technique for the identification of different chemical moieties/compounds contained in mixtures and has been successfully employed for the separation of small molecules based on hydrodynamic radii. Herein we show that DOSY can also be applied for the size determination of larger biomolecules such as proteins and protein oligomers/aggregates. Proof-of-principle is first shown with a cross-linked oligomeric protein mixture where the hydrodynamic volumes of each component are estimated and subsequently verified with size-exclusion HPLC and SDS polyacrylamide gel electrophoresis. We then determine the sizes of protein oligomers contained in a protein solution subjected under amyloid fibrillogenesis conditions. These studies aim to provide insight into the kinetics behind protein aggregation involved in amyloidosis as well as to determine the hydrodynamic radii of proteins within the mixture.


Asunto(s)
Proteínas/química , Difusión , Hidrodinámica , Cinética , Espectroscopía de Resonancia Magnética/métodos , Agregado de Proteínas/fisiología
14.
Environ Monit Assess ; 191(4): 239, 2019 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-30903290

RESUMEN

With rapid economic growth, road transport is contributing substantial adverse effects on urban air quality, especially in densely populated cities with high growth rate of GDP per capita, such as Macau. A high spatial-temporal resolution road traffic emission inventory is essential for assessment of environmental stresses imposed by local vehicle movements. To improve the accuracy and temporal-spatial resolution for emission inventory, through a bottom-up approach, link-based road traffic emission inventory with a spatial resolution of 0.1 km ∗ 0.1 km and a temporal resolution of 1 h for Macau in 2014 was developed by using a traffic model (VISUM), a road traffic emission model (TREM), the Geographic Information System (GIS), and the most up-to-date information available. Results show that the total annual emissions of CO, CO2, PM, NOX, and VOC in 2014 were 14,770, 413,099, 69, 1151, and 2945 tons, respectively. The estimated fuel consumption agreed well also with the statistical fuel consumption in Macau. Meanwhile, analysis of 3 scenarios on changes of road traffic emissions due to the operation of a light railway transit (LRT) system, variation on share of diesel, electric, and gasoline within the vehicle fleet, and replacement of vehicles with ones of Euro 5 and Euro 6 emission standards was carried out. This study provides a solid framework for developing high spatial-temporal resolution emission inventories for other densely populated cities of small area.


Asunto(s)
Contaminantes Atmosféricos/análisis , Contaminación del Aire/estadística & datos numéricos , Monitoreo del Ambiente , Emisiones de Vehículos/análisis , Ciudades , Gasolina , Sistemas de Información Geográfica , Macao
16.
Scand J Med Sci Sports ; 27(2): 161-166, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26688032

RESUMEN

The purpose of the study was to investigate the effect of an overhead target on the jump height and lower limb biomechanics in all three planes of motion in a vertical drop jump (VDJ) task among elite female handball and football (soccer) players. The hypothesis was that adding an overhead target to the VDJ task improves jump height, increases joint loading, and decreases frontal plane knee control. Five hundred and twenty-three female handball and football players (mean ± SD: 21 ± 4 years, 168 ± 6 cm, 65 ± 8 kg) completed the test. The overhead target increased jumping height by 5.8%. Furthermore, the overhead target led to statistically significant changes in many of the lower limb biomechanical variables examined. However, all the changes in kinematics and kinetics were clinically insignificant, as indicated by the small effect sizes. Strong to moderate positive Spearman's rank correlations were found between the two conditions. Therefore, an overhead target is unlikely to increase the range of responses in biomechanical variables in elite female handball and football athletes.


Asunto(s)
Atletas , Rendimiento Atlético/fisiología , Extremidad Inferior/fisiología , Adolescente , Adulto , Lesiones del Ligamento Cruzado Anterior/epidemiología , Lesiones del Ligamento Cruzado Anterior/fisiopatología , Fenómenos Biomecánicos , Estudios de Cohortes , Femenino , Humanos , Estudios Prospectivos , Factores de Riesgo , Fútbol , Adulto Joven
17.
Herz ; 42(7): 684-689, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27858114

RESUMEN

BACKGROUND: Bailout stenting after suboptimal paclitaxel-coated balloon (PCB) angioplasty is required in up to 28% of cases. We sought to compare the safety of bailout stenting with drug-eluting stents (DES) compared with the more established combination of PCB with bare metal stents (BMS). METHODS: We retrospectively evaluated all patients who had stents implanted owing to suboptimal PCB angioplasty results between January 2010 and April 2015. Endpoints analyzed were major adverse cardiac events (MACE) - defined as cardiovascular death, nonfatal myocardial infarction (MI), and target lesion revascularization (TLR) - as well as major and minor bleeding. RESULTS: Baseline clinical characteristics were comparable with a high proportion of diabetics in both groups (50.0% vs. 45.8%, p = 0.74). BMS and DES sizes were similar (mean diameter 2.72 ± 0.50 mm vs. 2.89 ± 0.56 mm, p = 0.20, length 25.22 ± 13.47 mm vs. 28.08 ± 9.08 mm, p = 0.47). Outcomes were comparable at the end of 1 year (MACE 12.2% vs. 9.5%, p = 1.00, TLR 6.1% vs. 4.8%, p = 1.00, MI 0% vs. 4.8%, p = 0.30). There was no case of stent thrombosis or major bleeding, and the rates of minor bleeding were similar (4.2% vs. 4.8%, p = 1.00). CONCLUSION: Our initial experience using DES instead of BMS as a bailout after suboptimal PCB results shows that the procedure is safe and effective at 1 year.


Asunto(s)
Angioplastia Coronaria con Balón/métodos , Estenosis Coronaria/cirugía , Stents Liberadores de Fármacos , Metales , Paclitaxel/administración & dosificación , Seguridad del Paciente , Stents , Anciano , Terapia Combinada , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/mortalidad , Complicaciones Posoperatorias/cirugía , Reoperación , Estudios Retrospectivos , Singapur
18.
Biochem Biophys Res Commun ; 482(4): 909-915, 2017 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-27894842

RESUMEN

In spite of a number of studies to characterize ferredoxin (Fd):ferredoxin NADP+ reductase (FNR) interactions at limited conditions, detailed energetic investigation on how these proteins interact under near physiological conditions and its linkage to FNR activity are still lacking. We herein performed systematic Fd:FNR binding thermodynamics using isothermal titration calorimetry (ITC) at distinct pH (6.0 and 8.0), NaCl concentrations (0-200 mM), and temperatures (19-28 °C) for mimicking physiological conditions in chloroplasts. Energetically unfavorable endothermic enthalpy changes were accompanied by Fd:FNR complexation at all conditions. This energetic cost was compensated by favorable entropy changes, balanced by conformational and hydrational entropy. Increases in the NaCl concentration and pH weakened interprotein affinity due to the less contribution of favorable entropy change regardless of energetic gains from enthalpy changes, suggesting that entropy drove complexation and modulated affinity. Effects of temperature on binding thermodynamics were much smaller than those of pH and NaCl. NaCl concentration and pH-dependent enthalpy and heat capacity changes provided clues for distinct binding modes. Moreover, decreases in the enthalpy level in the Hammond's postulate-based energy landscape implicated kinetic advantages for FNR activity. All these energetic interplays were comprehensively demonstrated by the driving force plot with the enthalpy-entropy compensation which may serve as an energetic buffer against outer stresses. We propose that high affinity at pH 6.0 may be beneficial for protection from proteolysis of Fd and FNR in rest states, and moderate affinity at pH 8.0 and proper NaCl concentrations with smaller endothermic enthalpy changes may contribute to increase FNR activity.


Asunto(s)
Ferredoxina-NADP Reductasa/metabolismo , Ferredoxinas/metabolismo , Hojas de la Planta/metabolismo , Proteínas de Plantas/metabolismo , Zea mays/metabolismo , Entropía , Cinética , Unión Proteica , Cloruro de Sodio/metabolismo , Termodinámica
19.
Proc Natl Acad Sci U S A ; 113(48): E7778-E7787, 2016 11 29.
Artículo en Inglés | MEDLINE | ID: mdl-27856732

RESUMEN

The parasite Trypanasoma brucei causes African trypanosomiasis, known as sleeping sickness in humans and nagana in domestic animals. These diseases are a major burden in the 36 sub-Saharan African countries where the tsetse fly vector is endemic. Untreated trypanosomiasis is fatal and the current treatments are stage-dependent and can be problematic during the meningoencephalitic stage, where no new therapies have been developed in recent years and the current drugs have a low therapeutic index. There is a need for more effective treatments and a better understanding of how these parasites evade the host immune response will help in this regard. The bloodstream form of T. brucei excretes significant amounts of aromatic ketoacids, including indolepyruvate, a transamination product of tryptophan. This study demonstrates that this process is essential in bloodstream forms, is mediated by a specialized isoform of cytoplasmic aminotransferase and, importantly, reveals an immunomodulatory role for indolepyruvate. Indolepyruvate prevents the LPS-induced glycolytic shift in macrophages. This effect is the result of an increase in the hydroxylation and degradation of the transcription factor hypoxia-inducible factor-1α (HIF-1α). The reduction in HIF-1α levels by indolepyruvate, following LPS or trypanosome activation, results in a decrease in production of the proinflammatory cytokine IL-1ß. These data demonstrate an important role for indolepyruvate in immune evasion by T. brucei.


Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Inmunidad Innata , Macrófagos/metabolismo , Piruvatos/metabolismo , Trypanosoma brucei brucei/inmunología , Tripanosomiasis Africana/inmunología , Animales , Línea Celular , Glucólisis , Células HEK293 , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Evasión Inmune , Indoles/metabolismo , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/metabolismo , Leucocitos Mononucleares/parasitología , Lipopolisacáridos/farmacología , Macrófagos/parasitología , Ratones Endogámicos C57BL , Tripanosomiasis Africana/parasitología
20.
J Mol Recognit ; 29(9): 446-51, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-27060481

RESUMEN

A fluorescent reporter, 8-anilino-1-naphthalene sulfonic acid (ANS), can serve as a reference molecule for conformational transition of a protein because its aromatic carbons have strong affinity with hydrophobic cores of partially unfolded molten globules. Using a typical calcium-binding protein, bovine α-lactalbumin (BLA), as a model protein, we compared the ANS binding thermodynamics to the decalcified (10 mM EDTA treated) apo-BLA at two representative temperatures: 20 and 40 °C. This is because the authentic molten globule is known to form more heavily at an elevated temperature such as 40 °C. Isothermal titration calorimetry experiments revealed that the BLA-ANS interactions at both temperatures were entropy-driven, and the dissociation constants were similar on the order of 10(-4) M, but there was a dramatic changeover in the binding thermodynamics from endothermic at 20 °C to exothermic at 40 °C. We believe that the higher subpopulation of authentic molten globules at 40 °C than 20 °C would be responsible for the results, which also indicate that weak binding is sufficient to alter the ANS binding mechanisms. We expect that the thermodynamic properties obtained from this study would serve as a useful reference for investigating the binding of other hydrophobic ligands such as oleic acid to apo-BLA, because oleic acid is known to have tumor-selective cytotoxicity when complexed with partially unfolded α-lactalbumin. Copyright © 2016 John Wiley & Sons, Ltd.


Asunto(s)
Naftalenosulfonatos de Anilina/metabolismo , Calor , Lactalbúmina/metabolismo , Termodinámica , Calorimetría , Concentración de Iones de Hidrógeno , Ácido Oléico/metabolismo , Unión Proteica , Pliegue de Proteína
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