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1.
Inorg Chem ; 59(3): 2051-2061, 2020 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-31967459

RESUMEN

Dioxygen O-O bond activation is a process for oxygenases and oxidases to perform biological functions and synthetic biomimetic catalysts to carry out oxygenation reactions using molecular O2 as an oxidant. Inspired by the experimental development of a CoIII-peroxo complex (i.e., [CoIII(TBDAP)(O2)]+, TBDAP = N,N-ditert-butyl-2,11-diaza[3.3](2,6)-pyridinophane) that exhibits dioxygenase-like reactivity to activate nitriles, a density functional theory (DFT) mechanistic study has been carried out to understand how the peroxo ligand is broken to activate nitriles. The study unveils that the O-O bond cleavage takes place via conversion to a CoII-superoxo complex aided by nitrile coordination, followed by formation of a five-membered intermediate via superoxo O2 radical nucleophilic attack at the nitrile carbon. Finally, a [1,3]-sigmatropic rearrangement-like process breaks the dioxygen bond. The otherwise difficult [1,3]-sigmatropic rearrangement is enabled by the mediation of CoIII(TBDAP) which alters a concerted rearrangement to a sequential process of O-O bond cleavage and N-O bond formation. Expectedly, the unveiling of the O-O bond cleavage mechanism could offer a clue for the development of biomimetic metal oxygenation catalysts.


Asunto(s)
Quelantes/química , Cobalto/química , Complejos de Coordinación/química , Teoría Funcional de la Densidad , Dioxigenasas/química , Peróxidos/química , Quelantes/síntesis química , Quelantes/metabolismo , Cobalto/metabolismo , Complejos de Coordinación/síntesis química , Complejos de Coordinación/metabolismo , Dioxigenasas/metabolismo , Modelos Moleculares , Estructura Molecular , Oxígeno/química , Oxígeno/metabolismo , Peróxidos/metabolismo
2.
Gene ; 735: 144332, 2020 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-31972310

RESUMEN

Dental pulp cells (DPCs) are multipotent cells, which can differentiate into various tissues and have the potential to treat many diseases. However, little is known about the molecular disorder mechanism. To explore the mechanism of molecular disorders and dysfunction of DPCs under hypoxia, we investigated the molecular effects of two hypoxic time lengths on DPCs. Differential analysis, protein interaction network (PPI), enrichment analysis and coupling analysis were further synthesized to identify human dental pulp cell dysfunction modules under hypoxic conditions. Based on the module aggregation of 579 genes, 13 dental pulp cell dysfunction modules were obtained. Importantly, we found that up to 12 modules were significantly involved in positive regulation of neurogenesis, positive regulation of nervous system development. Based on the predictive analysis of regulators, we identified a series of ncRNAs (including CRNDE, MALAT1, microRNA-140-5p, microRNA-300 and microRNA-30a-5p) and transcription factors (including E2F1). Based on the comprehensive functional module analysis, we identified the dysfunction module of human dental pulp cells (HDPCs) under hypoxia. The results suggest that nerve regulation plays an important role in regulating the dysfunction module of DPCs. These prominent pivotal regulators in the module were used as an important part of the molecular disorders of DPCs, may be an important part of the subnetwork of the manipulation module and affect the molecular dysregulation mechanism of DPCs. This study provides new directions and potential targets for further research.


Asunto(s)
Pulpa Dental/citología , Redes Reguladoras de Genes , Células Madre Mesenquimatosas/metabolismo , Oxígeno/metabolismo , Mapas de Interacción de Proteínas , Hipoxia de la Célula , Células Cultivadas , Humanos , MicroARNs/genética , MicroARNs/metabolismo
4.
Adv Exp Med Biol ; 1232: 3-9, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893387

RESUMEN

Neonates with hypoxic-ischaemic (HI) brain injury were monitored using a broadband near-infrared spectroscopy (NIRS) system in the neonatal intensive care unit. The aim of this work is to use the NIRS cerebral oxygenation data (HbD = oxygenated-haemoglobin - deoxygenated-haemoglobin) combined with arterial saturation (SaO2) from pulse oximetry to calculate cerebral blood flow (CBF) based on the oxygen swing method, during spontaneous desaturation episodes. The method is based on Fick's principle and uses HbD as a tracer; when a sudden change in SaO2 occurs, the change in HbD represents a change in tracer concentration, and thus it is possible to estimate CBF. CBF was successfully calculated with broadband NIRS in 11 HIE infants (3 with severe injury) for 70 oxygenation events on the day of birth. The average CBF was 18.0 ± 12.7 ml 100 g-1 min-1 with a range of 4 ml 100 g-1 min-1 to 60 ml 100 g-1 min-1. For infants with severe HIE (as determined by magnetic resonance spectroscopy) CBF was significantly lower (p = 0.038, d = 1.35) than those with moderate HIE on the day of birth.


Asunto(s)
Lesiones Encefálicas , Encéfalo , Circulación Cerebrovascular , Oximetría , Oxígeno , Espectroscopía Infrarroja Corta , Encéfalo/irrigación sanguínea , Encéfalo/diagnóstico por imagen , Lesiones Encefálicas/diagnóstico por imagen , Humanos , Recién Nacido , Oximetría/instrumentación , Oximetría/métodos , Oxígeno/metabolismo
5.
Adv Exp Med Biol ; 1232: 105-112, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893401

RESUMEN

BACKGROUND: We have repeatedly observed a right-left asymmetry (RLA) of prefrontal cerebral oxygenation of subjects during the resting state. AIM: To clarify if the RLA is a reliably observable phenomenon at the group level and whether it is associated with systemic physiology, absolute tissue oxygen saturation (StO2) or total hemoglobin concentration ([tHb]). MATERIAL AND METHODS: StO2 and [tHb] values at the right and left prefrontal cortex (PFC) were calculated for two 5- min resting phases based on data from 76 single measurements (24 healthy adults, aged 22.0 ± 6.4 years). StO2 and [tHb] were measured with an ISS OxiplexTS frequency domain near-infrared spectroscopy device. In addition, end-tidal CO2 (PETCO2), heart rate (HR), respiration rate (RR) and the pulse-respiration quotient (PRQ = HR/RR) were measured and analyzed for the two phases. RESULTS: On the group level it was found that i) StO2 was higher at the right compared to the left PFC (for both phases), ii) RLA of StO2 (∆StO2 = StO2 (right)-StO2 (left) was independent of PETCO2, HR and PRQ, and iii) ∆StO2 was associated with absolute StO2 and [tHb] values (positively and negatively, respectively). DISCUSSION AND CONCLUSION: This study shows that i) RLA of StO2 at the PFC is a real phenomenon, and that ii) ∆StO2 at the group level does not depend on PETCO2, HR, RR or PRQ, but on absolute StO2 and [tHb]. We conclude that the RLA is a real effect, independent of systemic physiology, and most likely reflects genuine properties of the brain, i.e. different activity states of the two hemispheres.


Asunto(s)
Hemoglobinas , Oxígeno , Corteza Prefrontal , Espectroscopía Infrarroja Corta , Adolescente , Adulto , Hemoglobinas/metabolismo , Humanos , Oxígeno/metabolismo , Consumo de Oxígeno , Corteza Prefrontal/metabolismo , Adulto Joven
6.
Adv Exp Med Biol ; 1232: 145-153, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893405

RESUMEN

The aim of the paper is to discuss what currently is feasible clinically to measure the level of oxygen and how that measurement can be clinically useful. Because oxygen in tissues is quite heterogeneous and all methods of measurement can only provide an average across heterogeneities at some spatial and temporal resolution, the values that are obtained may have limitations on their clinical utility. However, even if such limitations are significant, if one utilizes repeated measurements and focuses on changes in the measured levels, rather than 'absolute levels', it may be possible to obtain very useful clinical information. While these considerations are especially pertinent in cancer, they also pertain to most other types of pathology.


Asunto(s)
Oximetría , Oxígeno , Espectroscopía de Resonancia por Spin del Electrón , Humanos , Neoplasias/metabolismo , Oximetría/métodos , Oxígeno/análisis , Oxígeno/metabolismo
7.
Adv Exp Med Biol ; 1232: 155-168, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893406

RESUMEN

The success of treatment for malignancies, especially those undergoing radiation therapy or chemotherapy, has long been recognized to depend on the degree of hypoxia in the tumor. In addition to the prognostic value of knowing the tumor's initial level of hypoxia, assessing the tumor oxygenation during standard therapy or oxygen-related treatments (such as breathing oxygen-enriched gas mixtures or taking drugs that can increase oxygen supply to tissues) can provide valuable data to improve the efficacy of treatments. A series of early clinical studies of tumors in humans are ongoing at Dartmouth and Emory using electron paramagnetic resonance (EPR) oximetry to assess tumor oxygenation, initially and over time during either natural disease progression or treatment. This approach has the potential for reaching the long-sought goal of enhancing the effectiveness of cancer therapy. In order to effectively reach this goal, we consider the validity of the practical and statistical assumptions when interpreting the measurements made in vivo for patients undergoing treatment for cancer.


Asunto(s)
Neoplasias , Oximetría , Oxígeno , Hipoxia Tumoral , Espectroscopía de Resonancia por Spin del Electrón , Humanos , Neoplasias/metabolismo , Oxígeno/metabolismo
8.
Adv Exp Med Biol ; 1232: 177-182, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893408

RESUMEN

Tumor hypoxia may play a fundamental role in determining the radiotherapy outcome for several cancer types. Functional imaging with hypoxia specific radiotracers offers a way to visualize and quantify regions of increased radioresistance, which may benefit from dose escalation strategies. Conversion of the uptake in positron emission tomography (PET) images into oxygenation maps offers a way to quantitatively characterize the microenvironment. However, normalization of the uptake with respect to a well-oxygenated reference volume (WOV), which should be properly selected, is necessary when using conversion functions. This study aims at assessing the sensitivity of quantifying tumor oxygenation based on 18F-fluoromisonidazole (FMISO) PET with respect to the choice of the location and the oxygenation level of the WOV in head and neck cancer patients. WOVs varying not only in shape and location but also with respect to the assigned pO2 level were considered. pO2 values other than the standard 60 mmHg were selected according to the specific tissue type included in the volume. For comparison, the volume which would be considered as hypoxic based on a tissue-to-muscle ratio equal to 1.4 was also delineated, as conventionally done in clinical practice. Hypoxia mapping strategies are found highly sensitive to selection of the location of well-oxygenated region, but also on its assigned oxygenation level, which is crucial for hypoxia-guided adaptive dose escalation strategies.


Asunto(s)
Neoplasias de Cabeza y Cuello , Oximetría/instrumentación , Oximetría/normas , Oxígeno , Tomografía de Emisión de Positrones , Hipoxia Tumoral , Neoplasias de Cabeza y Cuello/fisiopatología , Humanos , Misonidazol/análogos & derivados , Misonidazol/metabolismo , Oxígeno/metabolismo , Microambiente Tumoral
9.
Adv Exp Med Biol ; 1232: 183-190, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893409

RESUMEN

Oxygen delivery to tissue mitochondria relies on simple diffusion in the target cells and tissues. As such, intracellular availability of O2 in tissue depends on its solubility and diffusivity in complex and heterogeneous macromolecular environments. The path of oxygen diffusion is key to its rate of transfer, especially where pathways of differing favorability are present. Most commonly, aqueous media, such as interstitial fluid and cytoplasm, are assumed to provide the dominant diffusion path. Here, the 'hydrophobic channeling' hypothesis is revisited, and several lines of evidence pointing toward lipid-accelerated oxygen diffusion pathways are discussed. The implications of hydrophobic channeling are considered in light of extended membrane networks in cells and tissues.


Asunto(s)
Células , Difusión , Metabolismo de los Lípidos , Oxígeno , Células/metabolismo , Interacciones Hidrofóbicas e Hidrofílicas , Lípidos/química , Mitocondrias/metabolismo , Oxígeno/metabolismo
10.
Adv Exp Med Biol ; 1232: 201-207, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893411

RESUMEN

Our previous research confirmed that patients with malignant hematopoietic disease already had a low hemoglobin level before allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, no study has determined whether a correlation exists between exercise load, hemoglobin level, and muscle oxygen saturation (SmO2), during exercise. Therefore, the purpose of this study was to investigate whether near-infrared spectroscopy (NIRS)-derived SmO2 is associated with exercise load, as determined by a dynamometer, before allo-HSCT. This study included 19 male patients who received allo-HSCT in Hyogo College of Medicine Hospital (Japan) between November 2009 and October 2012. Patients performed isometric repeated dorsiflexion at 50% maximum voluntary contraction for 180 s to determine exercise load, and SmO2 was evaluated during exercise at the same time using NIRS (BOM-L1TRW, Omega Wave, Inc., Japan). The hemoglobin level was also evaluated before allo-HSCT. Patients with hematopoietic disease before allo-HSCT already had a low hemoglobin level. There was a significant correlation between exercise load and ∆SmO2; however, the hemoglobin level was not correlated with exercise load. In these patients, exercise load might be affected by muscle oxygen consumption rather than by the hemoglobin level. This finding shows that NIRS can used to assess fatigue in patients with malignant hematopoietic disease.


Asunto(s)
Ejercicio , Enfermedades Hematológicas , Neoplasias Hematológicas , Hemoglobinas , Músculo Esquelético , Consumo de Oxígeno , Enfermedades Hematológicas/metabolismo , Enfermedades Hematológicas/fisiopatología , Neoplasias Hematológicas/metabolismo , Neoplasias Hematológicas/fisiopatología , Hemoglobinas/metabolismo , Humanos , Japón , Masculino , Músculo Esquelético/metabolismo , Oxígeno/metabolismo
11.
Adv Exp Med Biol ; 1232: 209-214, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893412

RESUMEN

Cognitive function is reported to improve by moderate aerobic exercise. However, the effects of intermittent exercise with rest between the moderate-intensity exercise are unclear. Therefore, this study aimed to compare the effects of continuous and intermittent exercise on cerebral oxygenation and cognitive function. This study included 18 healthy adults. For the continuous exercise protocol, 5 min of rest was followed by 30 min of exercise; 5 min of rest was allowed after each exercise. For the intermittent exercise protocol, 3 sets of 10 min of exercise were completed, with 5 min of rest between the sets. Exercise intensity was 50% of maximum oxygen uptake. Oxyhemoglobin (O2Hb) in the prefrontal cortex (PFC) was measured during each protocol, and cognitive tasks (Stroop test) were performed before and after exercise. O2Hb levels for the left and right PFCs were significantly higher post-exercise than pre-exercise for both exercise protocols (p < 0.01). The average reaction time in the Stroop test was significantly shorter post-exercise than pre-exercise for both protocols (p < 0.01). There was no significant difference in the error rate pre- and post-exercise for both protocols (continuous p = 0.22; intermittent p = 0.44). There was no significant difference between both protocols in all measurement results (O2Hb: p = 0.67; average reaction time p = 0.50; error rate p = 0.24). O2Hb was higher and average reaction time was shorter after exercise than before exercise for both exercise protocols. Intermittent and continuous exercise may improve cognitive function to the same degree after exercise.


Asunto(s)
Cerebro , Cognición , Ejercicio , Oxígeno , Espectroscopía Infrarroja Corta , Adulto , Cerebro/metabolismo , Cognición/fisiología , Humanos , Oxígeno/metabolismo , Consumo de Oxígeno
12.
Adv Exp Med Biol ; 1232: 231-237, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893415

RESUMEN

Near-infrared spectroscopy (NIRS) during cardiopulmonary exercise test (CPX) has shown a correlation between prefrontal cortex (PFC) oxygenated hemoglobin (O2Hb) level and negative affective responses. We hypothesized that O2Hb changes differ between the PFC and motor-related areas. This study investigated changes in hemoglobin levels in the PFC and motor-related areas during CPX. Twelve young healthy adults participated in this study. They performed a CPX after 4 min of rest and 4 min of warming up. Cortical O2Hb, deoxygenated hemoglobin (HHb), and total hemoglobin (THb) levels were measured with NIRS during CPX. Regions of interest (ROI) were the PFC, premotor area (PMA), supplementary motor area (SMA), and primary motor cortex (M1). The anaerobic threshold (AT), respiratory compensation (RC), and peak oxygen uptake (Peak) points were determined. The rest, AT, RC and Peak points of O2Hb, HHb, and THb were averaged over 5 s; hemoglobin slopes, from RC to the Peak points, were calculated to compare functional changes in cortical oxygenation. Average values of O2Hb, HHb, and THb in each ROI were compared among the rest, AT, RC, and Peak points. Average values of hemoglobin slopes, from RC to Peak points, were compared among ROIs using Bonferroni multiple comparisons. The HHb of all ROIs significantly increased at Peak point, compared with at the AT point. THb of the PFC, PMA, and SMA significantly increased at the RC or Peak points, compared with at the rest point. Hemoglobin slopes, from RC to Peak, showed no significant differences among ROIs. Each ROI exhibited similar changes, regardless of cortical function.


Asunto(s)
Corteza Motora , Oxígeno , Corteza Prefrontal , Espectroscopía Infrarroja Corta , Adulto , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Corteza Motora/metabolismo , Oxígeno/metabolismo , Consumo de Oxígeno , Oxihemoglobinas/metabolismo , Corteza Prefrontal/metabolismo , Adulto Joven
13.
Adv Exp Med Biol ; 1232: 239-244, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893416

RESUMEN

Near-infrared time-resolved spectroscopy (NIRTRS) can quantitatively evaluate mean optical path length (MPL). Since an increase in optical absorbers in the NIR region (e.g. an increase in deoxygenated hemoglobin during exercise) would shorten the MPL, the NIRS measurement area may vary depending on physical and physiological characteristics of the measurement region and/or the exercise intensity. The aim of this study was to examine the changes in MPL measured by NIRTRS during ramp cycling exercise between fat layer thickness-matched subjects with different aerobic capacities. Healthy control (CON, n = 8) and endurance-trained males (TR, n = 8) performed ramp cycling exercise until exhaustion. Deoxygenated hemoglobin concentration (Deoxy-Hb), total hemoglobin concentration (Total-Hb) and oxygenated hemoglobin concentration (Oxy-Hb) were evaluated by a three-wavelength NIRTRS system. MPL in each wavelength (MPL760, MPL800 and MPL830) was monitored continuously. With increasing exercise intensity, Total- and Deoxy-Hb significantly increased and Oxy-Hb decreased in both groups. Total- and Oxy-Hb during exercise were significantly higher in TR than CON (P < 0.05, P < 0.01, respectively). Furthermore, Deoxy-Hb also tended to be higher in TR than CON (P = 0.07). In addition, MPL at all wavelengths significantly shortened with an increase in exercise intensity, with no differences between CON and TR. In particular, MPL760 at peak exercise shortened more than 10% compared to the start of exercise in both groups, even though MPL830 decreased only a few per cent. These findings suggest that the NIRS measurement area may be reduced during ramp cycling exercise due to shortened MPL. Additionally, the changes in MPL may be especially greater at 760 nm than at the other wavelengths due to greater changes in Deoxy-Hb during exercise. Furthermore, this study indicates that the measurements of muscle deoxygenation using continuous-wave NIRS can be less accurate since they are significantly affected by changes in the optical path length.


Asunto(s)
Ejercicio , Consumo de Oxígeno , Músculo Cuádriceps , Adolescente , Adulto , Estudios de Casos y Controles , Prueba de Esfuerzo , Humanos , Masculino , Oxígeno/metabolismo , Oxihemoglobinas/metabolismo , Músculo Cuádriceps/metabolismo , Espectroscopía Infrarroja Corta , Adulto Joven
14.
Adv Exp Med Biol ; 1232: 253-259, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893418

RESUMEN

BACKGROUND: Near-infrared spectroscopy (NIRS) tissue oximeters enable non-invasive measurement of muscle oxygenation and perfusion. Several NIRS oximeters are currently available, particularly for muscle measurements. AIM: To evaluate the agreement of oxygenation and perfusion measurements obtained by two devices (Moxy, Fortiori Designs LLC, USA, and Nimo, Nirox, Italy) during an arterial occlusion test on the arm. SUBJECT AND METHODS: Arterial occlusions were conducted at the arm of one individual for 10 min with 200 mmHg. Measurements were made twice a day on five different days. Both NIRS devices were fixed at the arm (covering the muscles extensor carpi ulnaris, extensor digitorum, and flexor carpi ulnaris). RESULTS: The experiment revealed that i) both devices could detect changes in muscle oxygenation and perfusion during the occlusion, but ii) the magnitudes and dynamic changes differed between the two devices. DISCUSSION AND CONCLUSION: Both devices had different performances with regard to the measurement of tissue oxygenation and perfusion. This study shows that it might be worthwhile to compare all NIRS tissue oximeters currently available for muscle measurement in a large systematic study to increase the comparability of measurements obtained with different devices.


Asunto(s)
Oximetría , Oxígeno , Adulto , Humanos , Italia , Masculino , Músculo Esquelético/metabolismo , Oximetría/instrumentación , Oximetría/normas , Oxígeno/metabolismo , Consumo de Oxígeno , Espectroscopía Infrarroja Corta
15.
Adv Exp Med Biol ; 1232: 339-345, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893429

RESUMEN

We used a miniature broadband NIRS system to monitor concentration changes in brain oxygenation (oxy- and deoxy- haemoglobin [HbO2], [HHb]) and oxidised cytochrome-c-oxidase ([oxCCO]) during a high +Gz acceleration, induced by a human centrifuge, on two healthy experienced volunteers (2 male, 34 and 37 years). We performed a sequence of several +Gz exposures that were terminated at the onset of visual symptoms (loss of peripheral vision). Systemic parameters were recorded (i.e. heart rate, blood pressure and arterial saturation), and brain tissue blood volume changes ([HbT] = [HbO2] + [HHb]) and oxygen delivery ([HbDiff] = [HbO2] - [HHb]) were calculated. Volunteer 1 demonstrated a decrease in [HbT] of -3.49 ± 0.02 µMol and [HbDiff] of -3.23 ± 0.44 µMol, and an increase of [oxCCO] of 0.42 ± 0.01µMol. Volunteer 2 demonstrated a decrease in [HbDiff] of -4.37 ± 0.23 µMol, and no significant change in [HbT] (0.53 ± 0.06 µMol) and [oxCCO] (0.09 ± 0.06 µMol). The variability of the brain metabolic response was related to the level of ischaemia, suggesting that suppression of metabolism was due to lack of glucose substrate delivery rather than oxygen availability.


Asunto(s)
Aceleración , Complejo IV de Transporte de Electrones , Hemodinámica , Espectroscopía Infrarroja Corta , Adulto , Encéfalo/enzimología , Encéfalo/metabolismo , Complejo IV de Transporte de Electrones/metabolismo , Voluntarios Sanos , Humanos , Masculino , Estrés Oxidativo , Oximetría/instrumentación , Oxígeno/metabolismo
16.
Adv Exp Med Biol ; 1232: 347-354, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893430

RESUMEN

In preterm infants, there is a risk of long-term cognitive, motor and behavioral impairments due to hemorrhagic and/or ischemic lesions. If detected early, lesions can be prevented. A bedside imaging modality, capable of early detection of both disorders, is necessary. We present the state of development of a tomographic imager (named Pioneer), that will be capable of determining the oxygenation of the preterm-infant brain with high spatial resolution. Pioneer is a time-resolved near-infrared optical tomography (TR NIROT) instrument. It employs multiple wavelength laser light in short pulses on 11 distinct locations and measures the re-emerging light in a contactless fashion by means of a time-correlated single-photon counting (TCSPC) camera (named Piccolo) covering ~4.9 cm2 with 300 detectors. Timing response of the entire system is 116 ps. An in-house designed biocompatible source ring ensures fixed relative positions of sources and detectors and provides a secure interface between the patient and the probe. At the present state, the NIROT Pioneer system successfully detected a 6x6x50 mm3 inclusion 3 cm deep inside a phantom. These results confirm that the Pioneer imager is working as expected and is on a solid path towards full 3D tissue oxygenation imaging.


Asunto(s)
Encéfalo , Recien Nacido Prematuro , Oximetría , Oxígeno , Encéfalo/diagnóstico por imagen , Humanos , Recién Nacido , Oximetría/instrumentación , Oximetría/métodos , Oximetría/normas , Oxígeno/metabolismo , Fantasmas de Imagen
17.
Biosci Biotechnol Biochem ; 84(3): 481-490, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31690227

RESUMEN

ChlR is a MarR-type transcriptional regulator that activates the transcription of the chlAII-ho2-hemN operon in response to low oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803. Upon exposure to low oxygen conditions, ChlR activates transcription of the operon that encodes enzymes critical to tetrapyrrole biosynthesis under low oxygen conditions. We previously identified a super-activator variant, D35H, of ChlR that constitutively activates transcription of the operon. To gain insight into the low-oxygen induced activation of ChlR, we obtained eight additional super-activator variants of ChlR including D35H from pseudorevertants of a chlAI-disrupted mutant. Most substitutions were located in the N-terminal region of ChlR. Mapping of the substituted amino acid residues provided valuable structural insights that uncovered the activation mechanism of ChlR.


Asunto(s)
Proteínas Bacterianas/metabolismo , Cianobacterias/metabolismo , Oxígeno/metabolismo , Tetrapirroles/biosíntesis , Factores de Transcripción/metabolismo , Aerobiosis , Proteínas Bacterianas/química , Cianobacterias/crecimiento & desarrollo , Factores de Transcripción/química
18.
Aquat Toxicol ; 218: 105359, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31765944

RESUMEN

Carbohydrate metabolism switches from aerobic to anaerobic (glycolysis) to supply energy in response to acute hypoxic stress. Acute hypoxic stress with dissolved oxygen (DO) levels of 1.2 ±â€¯0.1 mg/L for 24 h and 12 h re-oxygenation was used to investigate the response of the anaerobic glycolytic pathway in Micropterus salmoides muscle. The results showed that the glucose concentration was significantly lower in muscle, while the lactic acid and pyruvic acid concentrations tended to increase during hypoxic stress. No significant difference was observed in muscle glycogen, and ATP content fluctuated significantly. The activities of gluconeogenesis-related enzymes were slightly elevated, such as phosphoenolpyruvate carboxykinase (PEPCK). The activities of the glycolytic enzymes increased after the induction of hypoxia, such as hexokinase (HK), pyruvate kinase (PK), and lactate dehydrogenase (LDH). Curiously, phosphofructokinase (PFK) activity was significantly down-regulated within 4 h during hypoxia, although these effects were transient, and most indices returned to control levels after 12 h of re-oxygenation. Upregulated hif-1α, ampkα, hk, glut1, and ldh mRNA expression suggested that carbohydrate metabolism was reprogrammed under hypoxia. Lactate transport was regulated by miR-124-5p according to quantitative polymerase chain reaction and dual luciferase reporter assays. Our findings provide new insight into the molecular regulatory mechanism of hypoxia in Micropterus salmoides muscle.


Asunto(s)
Aclimatación/fisiología , Lubina/metabolismo , Hipoxia/metabolismo , Ácido Láctico/metabolismo , MicroARNs/genética , Transportadores de Ácidos Monocarboxílicos/genética , Músculos/metabolismo , Simportadores/genética , Aclimatación/genética , Animales , Lubina/genética , Metabolismo de los Hidratos de Carbono/genética , Metabolismo de los Hidratos de Carbono/fisiología , Regulación de la Expresión Génica , Hipoxia/genética , Músculos/enzimología , Oxígeno/metabolismo
19.
Food Chem ; 310: 125741, 2020 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-31806389

RESUMEN

Polyphenol oxidase (PPO), also known as tyrosinase and catechol oxidase, is the enzyme responsible for enzymatic browning in foods. It causes undesirable organoleptic, nutritional and colour changes. Here, we report the preparation of five nanomaterials and a study of their ability to modulate PPO enzyme activity. The materials consist of UVM-7 supports (a mesoporous silica material) modified with diverse functional groups (i.e. amine, carboxylic acid, isocyanate, alkane and pyridine). We also studied the PPO immobilisation capability of the materials. All the materials, except the carboxylic acid functionalised one, offer high PPO loading capabilities and the immobilisation speed increases with functionalisation. Nevertheless, only a minor effect of the inhibition of enzymatic browning was produced. Furthermore, the amine containing material was able to capture not only PPO, but also the oxidation products. Such behaviour was validated with fresh apple juice in which browning was avoided, even 90 min in the presence of oxygen at room temperature.


Asunto(s)
Catecol Oxidasa/química , Catecol Oxidasa/metabolismo , Jugos de Frutas y Vegetales , Nanoestructuras/química , Dióxido de Silicio/química , Ácidos Carboxílicos/química , Ácido Edético/química , Enzimas Inmovilizadas/química , Enzimas Inmovilizadas/metabolismo , Malus/química , Oxidación-Reducción , Oxígeno/química , Oxígeno/metabolismo , Piridinas/química , Propiedades de Superficie
20.
Prep Biochem Biotechnol ; 50(1): 56-65, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31648576

RESUMEN

The optimum condition at which the halophilic salt-tolerant bacterium Halomonas variabilis (MTCC 3712) produces the maximum amount of extracellular polymeric substances (EPS) was investigated experimentally using response surface methodology based on the central composite design (CCD). Hyper-saline medium containing 1.5% w/v NaCl enriched nutrient medium with 1.5% glucose as a carbon source was used to produce about 4.74 g/L of EPS in 16 h compared to various other EPS production of this kind. The metabolic heat profile confirms net EPS production by HV was a growth-associated aerobic process. There is a good agreement between metabolic heat and Oxygen Uptake Rate (OUR). The maximum observed heat release was 2.1 W. The total protein content of the sample is 53% of the total EPS (Soluble EPS, Loosely bound EPS, and tightly bound EPS). The emulsifying and flocculating activities of the EPS were measured to explore the possibility of using the biopolymer for effluent treatment.


Asunto(s)
Matriz Extracelular de Sustancias Poliméricas/metabolismo , Halomonas/crecimiento & desarrollo , Reactores Biológicos , Glucosa/metabolismo , Halomonas/metabolismo , Calor , Oxígeno/metabolismo , Tolerancia a la Sal , Cloruro de Sodio/metabolismo
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