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Subthreshold depression is an essential precursor and risk factor for major depressive disorder, and its accurate identification and timely intervention are important for reducing the prevalence of major depressive disorder. Therefore, we used functional near-infrared spectroscopic imaging (fNIRS) to explore the characteristics of the brain neural activity of college students with subthreshold depression in the verbal fluency task. A total of 72 subthreshold depressed college students (SDs) and 67 healthy college students (HCs) were recruited, and all subjects were subjected to a verbal fluency task (VFT) while a 53-channel fNIRS device was used to collect the subjects' cerebral blood oxygenation signals. The results of the independent samples t -test showed that the mean oxyhemoglobin in the right dorsolateral prefrontal (ch34, ch42, ch45) and Broca's area (ch51, ch53) of SDs was lower than that of HCs. The peak oxygenated hemoglobin of SDs was lower in the right dorsolateral prefrontal (ch34) and Broca's area (ch51, ch53).The brain functional connectivity strength was lower than that of HCs. Correlation analysis showed that the left DLPFC and Broca's area were significantly negatively correlated with the depression level. SDs showed abnormally low, inadequate levels of brain activation and weak frontotemporal brain functional connectivity. The right DLPFC has a higher sensitivity for the differentiation of depressive symptoms and is suitable as a biomarker for the presence of depressive symptoms. Dysfunction in Broca's area can be used both as a marker of depressive symptoms and as a biomarker, indicating the severity of depressive symptoms. • Hypoperfusion in right DLPFC and Broca's area is physiological mechanisms distinguishing subthreshold depression. • Higher depression is associated with lower levels of cortical activation in the left DLPFC and Broca's area. • Subthreshold depression can be associated with low strength of overall brain functional connectivity. • fNIRS may be a potential tool to improve diagnostic accuracy for subthreshold depression. [ABSTRACT FROM AUTHOR]

Functional near-infrared spectroscopy (fNIRS) is a non-invasive technique frequently used to measure the brain hemodynamic activity in applications to evaluate affective disorders and stress. Using two wavelengths of light, it is possible to monitor relative changes in the concentrations of oxyhemoglobin and deoxyhemoglobin. Besides, the spatial asymmetry in the prefrontal cortex activity has been correlated with the brain response to stressful situations. We measured prefrontal cortex activity with a NIRS multi-distance device during a baseline period, under stressful conditions (e.g., social stress), and after a recovery phase. We calculated a laterality index for the contaminated brain signal and for the brain signal where we removed the influence of extracerebral hemodynamic activity by using a short channel. There was a significant right lateralization during stress when using the contaminated signals, consistent with previous investigations, but this significant difference disappeared using the corrected signals. Indeed, exploration of the susceptibility to contamination of the different channels showed non-homogeneous spatial patterns, which would hint at detection of stress from extracerebral activity from the forehead. There was no recovery phase between the social and the arithmetic stressor, a cumulative effect was not considered. Extracerebral hemodynamic activity provided insights into the pertinence of short channel corrections in fNIRS studies dealing with emotions. It is important to consider this issue in clinical applications including modern monitoring systems based on fNIRS technique to assess emotional states in affective disorders. • Stress increases are captured by fNIRS optodes on the forehead. • Extracerebral activity contributes to the prefrontal cortex (PFC) asymmetry index. • Heterogeneous extracerebral activity impacts fNIRS sensitivity to stress recovery. [ABSTRACT FROM AUTHOR]

The influence of hemoglobin and cytochrome с on the decomposition of the nitrosyl iron complex with thiosulfate ligands was studied. Oxyhemoglobin stabilizes the complex, the rate of NO generation decreases. Nitrosylated hemoglobin is formed in a mixture of methemoglobin with complex under anaerobic conditions. The complex reduces ferricytochrome с. [Display omitted] Nitrosyl complexes of non-heme iron (NICs) are the depot of nitric monoxide (NO) in the body. They nitrosylate heme-containing proteins in the process of decomposition. In this work, we studied the interaction of the thiosulfate complex Na 2 [Fe 2 (S 2 O 3) 2 (NO) 4 ]·4H 2 O (complex 1), as a promising drug agent, with hemoglobin and cytochrome c. It was found that complex 1 and its decomposition products are adsorbed on the surface of oxyhemoglobin, leading to longer NO generation compared to an aqueous buffer solution. In the system with metHb, the accumulation of the product (nitrosyl hemoglobin) occurs only under anaerobic conditions. The article also presents experimental data on the nitrosylation of ferro- and ferricytochrome c (cyt c2+ and cyt c3+, respectively) in the presence of complex 1. Cyt c2+ forms the product (NO)cyt c2+, which serves as the "depot" form of NO. This protein has a lesser stabilizing effect on complex 1 compared to hemoglobin. In the system with cyt c3+, nitrosylation of protein occurs during mixing, due to the presence of an oxidizing agent K 3 [Fe(CN) 6 ]. [ABSTRACT FROM AUTHOR]

Cerebrospinal fluid (CSF) reflects biochemical changes in the brain due to its direct contact with brain interstitial fluid, making it a valuable tool for diagnosing and monitoring disease progression and therapeutic effectiveness in clinical practice. However, collecting CSF in animal studies, particularly from small animals like rat pups or mice, poses significant challenges. After attempting various reported protocols, we encountered difficulties in consistently obtaining sufficient CSF from rat pups (P7-P42). Consequently, we modified these methods and developed a protocol with controllable and precise parameters for each step, enhancing reproducibility across different researchers. The newly developed method enables rapid, single-operator, and reproducible CSF extraction while ensuring high-quality (the absorbance of the "quality control solution" at 415 nm < 0.05 AU, an indicator of oxyhemoglobin contamination for the collected CSF samples) and high-yield samples (33 ± 2.128 μL for P7 pups, 34.10 ± 2.747 μL for P8 pups, 36.67 ± 3.997 μL for P9 pups, 36.90 ± 1.946 μL for P10 pups, 35.11 ± 3.285 μL for P10 hypoxic-ischemic brain damage (HIBD) pups and 51.70 ± 5.256 μL for P42 pups, respectively). Unlike existing methods of CSF extraction in rat pups, our protocol has reproducible capillary pipette pulling parameters, controllable CSF quality indexes, and can be operated by a single person with high yield in a short time. This paper provides a step-by-step comparison and discussion of the CSF collection process, establishing a method that enables a single operator to collect CSF rapidly, consistently, sufficiently, and with controlled quality. • Cerebrospinal fluid (CSF) is crucial in both clinical diagnosis of neurological disorders and scientific research. • It is important to avoid blood contamination during CSF collection. • Obtaining sufficient and high-quality CSF from rat pups (P7-P42) is currently challenging. • This modified method enables a single operator to collect CSF efficiently with high yield and quality. [ABSTRACT FROM AUTHOR]

• Optical imaging provides an inexpensive technique for monitoring ischemic brain. • Spreading depolarizations (SD) are coupled with transient flow and hemoglobin changes. • The oxyhemoglobin and flow transients correlate with ischemic brain injury. • The results motivate future clinical research on transcranial detection of SDs. Spreading depolarizations (SD) refer to the near-complete depolarization of neurons that is associated with brain injuries such as ischemic stroke. The present gold standard for SD monitoring in humans is invasive electrocorticography (ECoG). A promising non-invasive alternative to ECoG is diffuse optical monitoring of SD-related flow and hemoglobin transients. To investigate the clinical utility of flow and hemoglobin transients, we analyzed their association with infarction in rat focal brain ischemia. Optical images of flow, oxy-hemoglobin, and deoxy-hemoglobin were continuously acquired with Laser Speckle and Optical Intrinsic Signal imaging for 2 h after photochemically induced distal middle cerebral artery occlusion in Sprague-Dawley rats (n = 10). Imaging was performed through a 6 × 6 mm window centered 3 mm posterior and 4 mm lateral to Bregma. Rats were sacrificed after 24 h, and the brain slices were stained for assessment of infarction. We mapped the infarcted area onto the imaging data and used nine circular regions of interest (ROI) to distinguish infarcted from non-infarcted tissue. Transients propagating through each ROI were characterized with six parameters (negative, positive, and total amplitude; negative and positive slope; duration). Transients were also classified into three morphology types (positive monophasic, biphasic, negative monophasic). Flow transient morphology, positive amplitude, positive slope, and total amplitude were all strongly associated with infarction (p < 0.001). Associations with infarction were also observed for oxy-hemoglobin morphology, oxy-hemoglobin positive amplitude and slope, and deoxy-hemoglobin positive slope and duration (all p < 0.01). These results suggest that flow and hemoglobin transients accompanying SD have value for detecting infarction. [ABSTRACT FROM AUTHOR]

Functional near-infrared spectroscopy (fNIRS) signals are used to measure relative changes in oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) concentrations. Brain response studies constitute multilevel or nested datasets formed by different parts of the brain of individuals and multidimensional datasets. The changes in brain activities under specific stimuli are investigated with the help of statistical analysis. However, these studies ignore the dependence structure between the repeated measures of the same subject, which may cause inaccurate or incomplete findings. In this study, we adopt an advanced statistical method into HbO data controlling for variability within repeated measures of each subject while testing and measuring the degrees of the statistical significance between-subject factors and explanatory variables. The changes in HbO are investigated through a linear mixed model, taking experimental and demographic variables into account with open access neuroscience data. The channels nested within subjects are considered random to capture the differences among individuals. Our findings reveal that n-back conditions and mean response times of the subjects have statistically significant associations with mean HbO. • Significant contribution made by fNIRS optodes nested within subjects to the model. • The mean response time is significant for the changes in mean HbO concentration. • The mean HbO concentration differs among 2- and 3-back conditions. [ABSTRACT FROM AUTHOR]

• Behavior patterns and fNIRS were used to investigate neurocognitive mechanisms of distraction affecting pedestrian response. • Pedestrians responded more slowly when distracted by phone calls or texting compared to when undistracted or listening to music. • Higher cognitive load distraction impacted pedestrians' response and resulted in higher activation in cortices related to the mode of distraction. • Pedestrian's response to traffic lights were impaired by visual distraction, resulting in higher activation in occipital and prefrontal cortices. • Pedestrian's responses to car horns were impaired by auditory distraction, resulting in higher activation in temporal areas. Distracted walking is a major cause of pedestrian road traffic injuries, but little is known about how distraction affects pedestrian safety. The study was designed to explore how visual and auditory distraction might influence pedestrian safety. Three experiments were conducted to explore causal mechanisms from two theoretical perspectives, increased cognitive load from the distraction task and resource competition in the same sensory modality. Pedestrians' behavior patterns and cortex oxyhemoglobin changes were recorded while they performed a series of dual tasks. Four primary results emerged: (a) participants responded more slowly to both visual and auditory stimuli in traffic, as well as walked more slowly, while talking on the phone or text messaging compared to when undistracted or listening to music; (b) when participants completed pedestrian response tasks while distracted with a high cognitive load, their response was significantly slower and poorer than when they carried out a lower cognitive load distraction task, (c) participants had higher levels of oxy-Hb change in cortices related to visual processing and executive function while distracted with a higher cognitive load; and (d) participants' responses to traffic lights were slower and resulted in a higher activation in prefrontal cortex and occipital areas when distracted by a visual distraction task compared to when distracted with an auditory task; similarly, brain activation increased significantly in temporal areas when participants responded to an auditory car horn task compared to when they responded to visual traffic lights. Both distracting cognitive load demands and the type of distraction task significantly affect young adult pedestrian performance and threaten pedestrian safety. Pedestrian injury prevention efforts should consider the effects of the type of distracting task and its cognitive demands on pedestrian safety. [ABSTRACT FROM AUTHOR]

• DRS can measure blood oxygenation parameters from foot sole during leg elevation. • Significant changes in RHb and HbO 2 are seen above 45° of leg elevation. • SO 2 and HR remains same with leg elevation. • PI, ankle SBP and DBP decreases with respect to leg elevation. This study investigated the applicability of diffuse reflectance spectroscopy (DRS) for real-time and non-invasive measurement of blood oxygenation parameters (BOPs) such as reduced hemoglobin (RHb), oxyhemoglobin (HbO 2), and oxygen saturation (SO 2) from human foot sole during leg elevation. Seventeen (17) healthy male subjects aged between 21 to 39 years were included in this study. Diffuse reflectance spectra were recorded from measurement sites namely the 5th metatarsal, ball of great joint, calcaneum, and great toe of the human foot sole w.r.t. leg elevation angles such as 00, 150, 300, 450, and 600, respectively. The localized BOPs were derived from the recorded spectra. In addition, blood hemodynamic parameters (BHPs) such as heart rate (HR), SO 2 , perfusion index (PI), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were also measured for each elevating angle. To study and assess the changes in BOPs and BHPs w.r.t. leg elevation, a One-way ANOVA test followed by a Tukey HSD post-hoc test was performed. We observed a statistically significant increase in RHb (p < 0.001) and a decrease in HbO 2 (p < 0.001) after 45° of leg elevation, however, there was no statistically significant difference in SO 2 (p = 0.74) and HR (p = 0.84) for each measurement site w.r.t. leg elevation, respectively. Furthermore, PI (p < 0.01), ankle SBP (p < 0.001) and DBP (p < 0.001) were decreased w.r.t. leg elevation. The obtained results are in agreement with the literature. The preliminary results suggest that DRS has the potential for real-time estimation of BOPs from the local sites of healthy human foot soles during leg elevation. Thus, it opens the possibility of DRS to monitor and evaluate the diagnosis and treatment of ischemia and edema during leg elevation of patients through BOPs measurement. [ABSTRACT FROM AUTHOR]

Aminoacetone (1-aminopropan-2-one), a putative minor biological source of methylglyoxal, reacts like other α-aminoketones such as 6-aminolevulinic acid (first heme precursor) and 1,4-diaminobutanone (a microbicide) yielding electrophilic α-oxoaldehydes, ammonium ion and reactive oxygen species by metal- and hemeprotein-catalyzed aerobic oxidation. A plethora of recent reports implicates triose phosphate-generated methylglyoxal in protein crosslinking and DNA addition, leading to age-related disorders, including diabetes. Importantly, methylglyoxal-treated hemoglobin adds four water-exposed arginine residues, which may compromise its physiological role and potentially serve as biomarkers for diabetes. This paper reports on the co-oxidation of aminoacetone and oxyhemoglobin in normally aerated phosphate buffer, leading to structural changes in hemoglobin, which can be attributed to the addition of aminoacetone-produced methylglyoxal to the protein. Hydroxyl radical-promoted chemical damage to hemoglobin may also occur in parallel, which is suggested by EPR-spin trapping studies with 5,5-dimethyl-1-pyrroline-N-oxide and ethanol. Concomitantly, oxyhemoglobin is oxidized to methemoglobin, as indicated by characteristic CD spectral changes in the Soret and visible regions. Overall, these findings may contribute to elucidate the molecular mechanisms underlying human diseases associated with hemoglobin dysfunctions and with aminoacetone in metabolic alterations related to excess glycine and threonine. [Display omitted] • Hemoglobin and aminoacetone co-oxidation yield methylglyoxal and oxyradicals. • Oxyhemoglobin increase de aminoacetone oxidation rate. • Superoxide and hydroxyl radicals plus H 2 O 2 are reaction products. • Oxyhemoglobin is oxidized to metHb and undergoes structural alterations. • Aminoacetone may be implicated in Trp/Gly-related disorders. [ABSTRACT FROM AUTHOR]

Background: The prognosis for cardiac arrest (CA) is associated with the degree of cerebral ischemia. We investigated the relationship between the wavelet coherence of cerebral oxyhemoglobin (HbO2) among different channels and outcomes after CA. Moreover, we aimed to develop a prognostication method after CA.Methods: Eighty-three post-resuscitation patients were included. The HbO2 data were collected during the post-resuscitation period (median day, 1) using functional near-infrared spectroscopy. The coherence between sections of prefrontal HbO2 oscillations in five frequency intervals (I, 0.6-2 Hz; II, 0.15-0.6 Hz; III, 0.05-0.15 Hz; IV, 0.02-0.05 Hz; and V, 0.0095-0.02 Hz) were analyzed. We evaluated the outcomes using cerebral performance category (CPC) scores (good outcome, CPC ≤ 2 and poor outcome, CPC ≥ 3) at 3 months after CA. Additionally, the predictive method was developed using the biomarker and coherence value after CA.Results: Among the included patients, 19 patients (22.9%) had a good outcome. Poor outcome group had significantly lower phase coherence in the myogenic frequency interval III compared to good outcome group (0.36 ± 0.14 vs. 0.54 ± 0.18, P < 0.001). The predictive method using neuron-specific enolase (NSE) and interval III value demonstrated good discrimination (area under the curve 0.919; 95% confidence interval, 0.850-0.989).Conclusions: The predictive method using NSE and phase coherence of HbO2 in the interval III from the vascular smooth muscle cells could be a useful tool for prognosticating after CA. This suggests that evaluating cerebral ischemia using phase coherence of HbO2 might be a helpful outcome predictor following CA. [ABSTRACT FROM AUTHOR]

Functional near-infrared spectroscopy (fNIRS) is a neuroimaging technique that measures cortical blood flow to infer neural activation. Traditionally limited to laboratory settings due to high costs and complex operation, recent advancements have introduced mobile fNIRS devices, significantly broadening the scope of potential research participants. This study validates the use of the Mendi, a two-channel mobile fNIRS system, for measuring prefrontal oxyhemoglobin concentration changes during an n-back task. We manipulated task difficulty through different n-back levels (one-back versus three-back), revealing increased oxyhemoglobin concentrations in the prefrontal cortex during the more demanding three-back task compared to the one-back task. This finding demonstrates the Mendi's ability to distinguish between low and high cognitive task loads. Behavioural data, showing a decrease in accuracy under high load conditions, further corroborates these neuroimaging findings. Our study validates the Mendi mobile fNIRS system as an effective tool for assessing working memory load and underscores its potential in enhancing neuroscientific research accessibility. The user-friendly and cost-effective nature of mobile fNIRS systems like the Mendi opens up neuroscientific research to a diverse set of participants, enabling the investigation of neural processes in real-world environments across a variety of demographic groups. • Mendi fNIRS Validation : Effective in tracking prefrontal cortex activity. • Oxyhemoglobin Rise : Higher is demanding cognitive tasks. • Behavioural-Neural Link : Accuracy drops with increased cognitive load. • Enhanced Access : Mendi's mobile design opens new research avenues. • Real-World Application : Mobile fNIRS shows diverse demographic potential. [ABSTRACT FROM AUTHOR]

Background Aneurysmal subarachnoid hemorrhage (aSAH) is often complicated by the occurrence of delayed ischemic neurologic deficits (DIND), which impairs the clinical outcome of patients. The release of oxyhemoglobin (oxyHb) from lysing erythrocytes into cerebrospinal fluid (CSF) may critically contribute to the development of DIND. Methods Ventricular CSF of 18 high-grade (Fisher 3 and 4) aSAH patients was sampled daily from external ventricular drains between days 0 and 14 after bleeding. CSF was spectrophotometrically analyzed with precise quantification of cell-free oxyHb levels. Results OxyHb levels in CSF showed a delayed peak reaching the highest levels in the high-risk period for developing of DIND between days 3 and 14 after aneurysm rupture. Patients with DIND had a significantly higher cumulative oxyHb exposure within the first week after bleeding. Conclusions OxyHb levels in CSF may be useful as a biomarker to predict DIND in aSAH patients. The contribution of oxyHb in CSF to the pathogenesis of DIND should be further investigated as a potential therapeutic target. Highlights • Oxyhemoglobin levels in CSF peak in the high-risk period for developing of DIND in aSAH patients. • Increased oxyhemoglobin levels precede secondary clinical deterioration in patients with DIND. • Patients with DIND had a significantly higher cumulative oxyHb exposure. [ABSTRACT FROM AUTHOR]

Developing effective photodynamic theranostics for real-time monitoring of oxygen saturation at a specific target for photodynamic therapy (PDT) is highly desirable, but remains a great challenge owing to the separation of monitoring units and PDT units in existing methods. In this study, we report the real-time monitoring of tissue oxygen saturation (StO 2 ) during PDT using an 808 nm-excited upconversion nanoagent, UCNP-RB-RGD, fabricated by loading the photosensitiser rose bengal (RB) into amphiphilic upconversion nanoparticles, followed by conjugation with the tumour-targeting peptide c(RGDyK). Using the as-prepared UCNP-RB-RGD, we demonstrated that the upconversion luminescence at 645 nm and 540 nm under 808 nm laser irradiation could be used to simultaneously monitor StO 2 and activate RB for PDT. Furthermore, benefitting from this new photodynamic theranostic approach, the PDT efficacy was significantly enhanced by controllable adjuvant oxygen inhalation to resist the consumption of oxygen. The StO 2 monitoring unit and PDT unit were integrated into the single nanoagent UCNP-RB-RGD, providing high spatiotemporal consistency for the photo-controlled monitoring of StO 2 and localised activation of PDT; this system has potential for effective and accurate personalised PDT. [ABSTRACT FROM AUTHOR]

In this study, fused electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) techniques were utilized to examine the relationship between the ERP (event-related potential) component P300 and fNIRS hemodynamic signals for high-accuracy deception detection. During the performance of a modified concealed information test (CIT) task, a series of Chinese names were presented, which served as the target, irrelevant, or the probe stimuli for both the guilty and innocent groups. For participants in the guilty group, the probe stimulus was their individual name, whereas for the innocent group, the probe stimulus was one irrelevant name. In particular, data from concurrent fNIRS and ERP recordings were carefully inspected for participants from the two groups. Interestingly, we discovered that for the guilty group, the probe stimulus elicited significantly higher P300 amplitude at parietal site and also evoked significantly stronger oxyhemoglobin (HbO) concentration changes in the bilateral superior frontal gyrus and bilateral middle frontal gyrus than the irrelevant stimuli. However, this is not the case for the innocent group, in which participants exhibited no significant differences in both ERP and fNIRS measures between the probe and irrelevant stimuli. More importantly, our findings also demonstrated that the combined ERP and fNIRS feature was able to differentiate the guilty and innocent groups with enhanced sensitivity, in which AUC (the area under Receiver Operating Characteristic curve) is 0.94 for deception detection based on the combined indicator, much higher than that based on the ERP component P300 only (0.85) or HbO measure only (0.84). [ABSTRACT FROM AUTHOR]

In microorganisms, flavohemoglobins (FHbs) containing FAD and heme (Fe 3+ , metHb) convert NO. into nitrate at the expense of NADH and O 2 . FHbs contribute to bacterial resistance to nitrosative stress. Therefore, inhibition of FHbs functions may decrease the pathogen virulence. We report here a kinetic study of the reduction of quinones and nitroaromatic compounds by S. aureus FHb. We show that this enzyme rapidly reduces quinones and nitroaromatic compounds in a mixed single- and two-electron pathway. The reactivity of nitroaromatics increased upon an increase in their single-electron reduction potential ( E 1 7 ), whereas the reactivity of quinones poorly depended on their E 1 7 with a strong preference for a 2-hydroxy-1,4-naphthoquinone structure. The reaction followed a ‘ping-pong’ mechanism. In general, the maximal reaction rates were found lower than the maximal presteady-state rate of FAD reduction by NADH and/or of oxyhemoglobin (HbFe 2+ O 2 ) formation (~130 s −1 , pH 7.0, 25 °C), indicating that the enzyme turnover is limited by the oxidative half-reaction. The turnover studies showed that quinones prefreqently accept electrons from reduced FAD, and not from HbFe 2+ O 2 . These results suggest that quinones and nitroaromatics act as ‘subversive substrates’ for FHb, and may enhance the cytotoxicity of NO. by formation of superoxide and by diverting the electron flux coming from reduced FAD. Because quinone reduction rate was increased by FHb inhibitors such as econazole, ketoconazole, and miconazole, their combined use may represent a novel chemotherapeutical approach. [ABSTRACT FROM AUTHOR]

Transcranial direct current stimulation (tDCS) has been shown to be effective in treating some of the symptoms of schizophrenia. In the current study, we sought to determine whether oxy-hemoglobin ([oxy-Hb]), measured by near-infrared spectroscopy (NIRS), is associated with effects of transcranial direct current stimulation (tDCS) on psychotic symptoms of schizophrenia. Twenty-six patients underwent tDCS (2 mA × 20 min) two times per day for five consecutive days. The anodal electrode was placed over the left dorsolateral prefrontal cortex while the cathodal electrode was placed over the right supraorbital region. One month after the last administration of tDCS, positive, but not negative symptoms, evaluated by the Positive and Negative Syndrome Scale (PANSS), were significantly improved. At baseline, regional [oxy-Hb] concentrations in the brain were measured by a 52-channel NIRS instrument. Significant negative correlation was demonstrated between [oxy-Hb] concentrations of left temporoparietal regions throughout verbal fluency tasks vs. changes of PANSS Positive and Negative subscale scores. This is the first study to demonstrate the correlation between the response of neural activity to cognitive tasks at baseline and the ability of tDCS to improve positive and negative psychotic symptoms. Our observations suggest that NIRS provides a marker to predict the response to treatment with tDCS in schizophrenia. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the association of polysomnographic parameters with clinical symptom severity in Robin sequence (RS) patients.Methods: All patients diagnosed as presenting with RS at Hospital de Clínicas de Porto Alegre from October 2012 to June 2016 were enrolled. They were classified as isolated RS, RS-plus, and syndromic RS. Polysomnography (PSG) was performed, except for those patients in need of respiratory support. Symptom severity was evaluated as defined by the Cole et al.Classification: Ordinal OR (for the chance of increase in one grade on the clinical severity scale) and R2 (determination coefficient from ordinal logistic regression) were computed from data analysis.Results: A total of 80 participants were enrolled in the study. Fifty-five of these were able to undergo polysomnography. Worsening of the studied PSG parameters was associated with increase in clinical severity grading, as follows: desaturation index (OR 1.27; 95% CI; 1.07-1.51; R2 = 19.8%; p = 0.006); apnea/hypopnea Index (OR 1.13; 95% CI; 1.01-1.26; R2 = 12.5%; p = 0.02); sleep mean oxygen saturation (OR 0.16; 95% CI; 0.05-0.52; R2 = 22.6%; p = 0.002); oxygen saturation nadir (OR 0.73; 95% CI; 0.56-0.96; R2 = 10.0%; p = 0.02); percentage of time with oxygen saturation <90% (OR 9.49; 95% CI; 1.63-55.31, R2 = 37.6%; p = 0.012); and percentage of time presenting with obstruction (OR 2.5; 95% CI; 1.31-4.76; R2 = 25.1%; p = 0.006).Conclusions: Polysomnography parameters were associated with severity of clinical manifestations in patients with RS. Oxyhemoglobin saturation-based parameters had surprisingly significant R2 values. Therefore, those parameters, which have traditionally been undervalued in other clinical settings, should also be assessed in the polysomnographic evaluation of RS patients. [ABSTRACT FROM AUTHOR]

Red blood cells (RBCs)-based vesicles have been widely used for drug delivery due to their unique advantages. Intact RBCs contain a large amount of oxyhemoglobin (oxyHb), which can assist with photodynamic therapy (PDT). Indocyanine green (ICG), a photosensitizer both for photothermal therapy (PTT) and PDT, shows potent anticancer efficacy when combined with chemotherapeutic drug doxorubicin (DOX). In this study, we prepared nanoscaled RBCs (RAs) containing oxyHb and gas-generating agent ammonium bicarbonate (ABC) for co-loading and controlled release of ICG and DOX, thus hoping to achieve synergistic effects of PTT/PDT and chemotherapy against breast cancer. Compared to free ICG, ICG and DOX co-loaded RAs (DIRAs) exhibited nearly identical PTT efficiency both in vitro and in vivo, but meanwhile their PDT efficiency was enhanced significantly. In mouse breast cancer cells, DIRAs significantly inhibited cell growth and induced cell apoptosis after laser irradiation. In breast tumor-bearing mice, intratumoral injection of DIRAs and followed by local laser irradiation almost completely ablated breast tumor and further suppressed tumor recurrence and metastasis. In conclusion, this biomimetic multifunctional nanosystem can facilitate breast cancer treatment by combining PTT/PDT and chemotherapy. [ABSTRACT FROM AUTHOR]

Functional near infrared spectroscopy (fNIRS) is a safe, non-invasive, relatively quiet imaging technique that is tolerant of movement artifact making it uniquely ideal for the assessment of hearing mechanisms. Previous research demonstrates the capacity for fNIRS to detect cortical changes to varying speech intelligibility, revealing a positive relationship between cortical activation amplitude and speech perception score. In the present study, we use an event-related design to investigate the hemodynamic response in the temporal lobe across different listening conditions. We presented participants with a speech recognition task using sentences in quiet, sentences in noise, and vocoded sentences. Hemodynamic responses were examined across conditions and then compared when speech perception was accurate compared to when speech perception was inaccurate in the context of noisy speech. Repeated measures, two-way ANOVAs revealed that the speech in noise condition (−2.8 dB signal-to-noise ratio/SNR) demonstrated significantly greater activation than the easier listening conditions on multiple channels bilaterally. Further analyses comparing correct recognition trials to incorrect recognition trials (during the presentation phase of the trial) revealed that activation was significantly greater during correct trials. Lastly, during the repetition phase of the trial, where participants correctly repeated the sentence, the hemodynamic response demonstrated significantly higher deoxyhemoglobin than oxyhemoglobin, indicating a difference between the effects of perception and production on the cortical response. Using fNIRS, the present study adds meaningful evidence to the body of knowledge that describes the brain/behavior relationship related to speech perception. [ABSTRACT FROM AUTHOR]

The cognitive neuroscience of aging is a growing and stimulating research area. The development of neuroimaging techniques in the past two decades has considerably increased our understanding of the brain mechanisms that might underlie cognitive performance and resulting changes due to normal aging. Beside traditional metabolic neuroimaging techniques, such as Positron Emission Tomography and functional Magnetic Resonance Imaging, near infrared spectroscopy (NIRS), an optical imaging technique allowing to monitor real-time cerebral blood oxygenation, has gained recent interest in this field. The aim of the present review paper, after briefly presenting the NIRS technique, is to review and to summarize the recent results of neuroimaging studies using this technique in the field of cognitive aging. The reviewed literature shows that, despite low spatial resolution and cerebral depth penetration, this technique provides consistent findings on the reduced hemodynamic activity as a function of chronological age, mainly in the prefrontal cortex. Important moderators of brain hemodynamics, such as cognitive load, subjects’ characteristics and experimental conditions, for which the NIRS technique is sensitive, are discussed. Strengths and weaknesses of functional NIRS in the field of cognitive aging are presented and finally, novel perspectives of research are proposed. [ABSTRACT FROM AUTHOR]

The ability of the somatosensory cortex in differentiating various tactile sensations is very important for a person to perceive the surrounding environment. In this study, we utilize a lab-made multi-channel functional near-infrared spectroscopy (fNIRS) to discriminate the hemodynamic responses (HRs) of four different tactile stimulations (handshake, ball grasp, poking, and cold temperature) applied to the right hand of eight healthy male subjects. The activated brain areas per stimulation are identified with the t -values between the measured data and the desired hemodynamic response function. Linear discriminant analysis is utilized to classify the acquired data into four classes based on three features (mean, peak value, and skewness) of the associated oxy-hemoglobin (HbO) signals. The HRs evoked by the handshake and poking stimulations showed higher peak values in HbO than the ball grasp and cold temperature stimulations. For comparison purposes, additional two-class classifications of poking vs. temperature and handshake vs. ball grasp were performed. The attained classification accuracies were higher than the corresponding chance levels. Our results indicate that fNIRS can be used as an objective measure discriminating different tactile stimulations from the somatosensory cortex of human brain. [ABSTRACT FROM AUTHOR]

Emotional working memory (EWM) is suggested as a working memory (WM) type, distinguished to process emotional stimuli, and may or may not be spared in Alzheimer's disease (AD). The aim was to compare patients with AD and healthy older adults (HC) on verbal EWM performance and accompanying prefrontal cortex activity. Twenty AD patients along with 20 HC individuals are required to complete an emotional one-back task in three conditions (neutral, positive and negative word lists). Prefrontal oxyhemoglobin (oxyHb) concentrations were measured simultaneously by a 24- channel functional near infrared spectroscopy device. Correct response rates were similar in two groups in all conditions. Reaction times were comparable in the EWM positive condition but longer in the AD group in EWMneutral and negative conditions. In the HC group, emotional words had no significant effect on WM. On the other hand, positive compared to neutral words led to greater activation in the left ventral prefrontal cortex (VPFC) in AD group. When compared to HCs, activity in the VPFC was significantly higher in AD patients during the positive condition. Positive words facilitated WM performance in participants with AD. Activity in VPFC may be the functional correlate of this phenomenon. [ABSTRACT FROM AUTHOR]

We develop a theory of oxygen hemoglobin association and derive the oxygen hemoglobin association equation and determine the values of the four association constants by curve fitting four commonly accepted data points that relate oxygen saturation and oxygen partial pressure (PO 2) in the blood using mathematical reasoning and chemical kinetics. The four association constants come from the progression of oxygen binding to each of the four subunits on the hemoglobin molecule in a cooperative manner. The binding of oxygen alters the affinity of subsequent binding of additional oxygen molecules, which is reflected in changing magnitudes of the association constants. We also demonstrate rather surprisingly that the value of the third association constant is significantly smaller than all other association constants and offer some conjecture about this puzzling finding. With our equation, we can compute the distributions of all five oxyhemoglobin species at various PO 2 levels that are published for the first time in the history of hemoglobin research. After examining the distributions, we find the triply bound oxyhemoglobin exists in very low concentration, consistent with the small third association constant. In addition, we present the oxygen levels where maximal concentrations of various oxyhemoglobin species occur, another unexpected finding that was never published before. Finally, we determine the inflection point of the hemoglobin association curve, a defining property to a specific sigmoid curve, representing the steepest portion of the curve. One sentence summary : We develop a theory of oxygen hemoglobin association based upon first order chemical kinetics and the principle of cooperativity and provide for the first time accurate oxygen hemoglobin association constants for each step of the four steps of oxygen and hemoglobin binding. [ABSTRACT FROM AUTHOR]

Ferrochelatase (FeCH), present in pork liver, catalyses the formation of zinc-protoporphyrin (ZnPP), a stable purple-red pigment found in Parma ham. Kinetics of ZnPP formation is especially slow. Thus, the aim of this study was to improve the ZnPP production using power ultrasound (US) at low (7.05 W/L) and moderate power (36.53 W/L) in homogenised pork liver (HLi) and with added oxyhemoglobin (HLi + OxyHb). ZnPP formation was performed at 37 °C, under anaerobic conditions, for different reaction times (6–48 h). When US was applied at low power, it shortened the time needed to reach maximum ZnPP formation by 50% and increased the yield by 25.77% in the case of HLi and by 4.42% in that of HLi + OxyHb, when compared to the control experiments; however, for the moderate power, ZnPP formation was hindered. Therefore, low power US proved to be an effective method with which to intensify enzymatic ZnPP production. • Power ultrasound (US) intensified the ZnPP formation with use in the food industry. • US effect depended mainly on the applied ultrasonic power. • A moderate US power led to the temperature rise negatively affecting ZnPP formation. • Low power US application shortened the time needed to reach ZnPP max by 50%. • Low power US application increased ZnPP max up to 25.77%. [ABSTRACT FROM AUTHOR]

Transcranial direct current stimulation (tDCS) has been explored as a potential method for cognitive enhancement. tDCS may induce a cascade of neurophysiological changes including alterations in cerebral oxygenation. However, the effects of tDCS on the cognitive-cerebral oxygenation interaction remains unclear. Further, oxygenation variability across individuals remains minimally controlled for. The purpose of this sham-controlled study was to test the effects of anodal tDCS over the right dorsolateral prefrontal cortex (DLPFC) on the interaction between working memory and cerebral oxygenation while controlling for individual oxygenation variability. Thirty-three adults received resting-state functional near-infrared spectroscopy (fNIRS) recordings over bilateral prefrontal cortices. Following this, working memory was tested using a Toulouse n- back task concurrently paired with fNIRS, with measurements taken before and after 20 min of anodal or sham tDCS at 1.5 mA. With individual oxygenation controlled for, anodal tDCS was found to increase the oxyhemoglobin concentration over the right DLPFC during the 2-back (q =.015) and 3-back (q =.008) conditions. Additionally, anodal tDCS was found to improve accuracy during the 3-back task by 13.4 % (p =.028) and decrease latency by 250 ms (p =.013). The increase in oxyhemoglobin was strongly correlated with increases in accuracy (p =.041) and decreases in latency during the 3-back span (p =.017). Taken together, anodal tDCS over the right DLPFC was found to regionally increase oxyhemoglobin concentrations and improve working memory performance in higher cognitive load conditions. • tDCS over the DLPFC may augment cognitive processing and cerebral oxygenation. • Individual cerebral oxygenation is variable and should be controlled for. • tDCS was found to increase oxyhemoglobin (HbO) over the stimulated right DLPFC. • tDCS increased working memory and decreased reaction time in higher load phases. • Increases in HbO are correlated with cognitive improvement in higher load phases. [ABSTRACT FROM AUTHOR]

Objective: To assess the impact of three hypopnea definitions on the severity classification of obstructive sleep apnea (OSA) and its association with cardiovascular mortality risk in women and elderly individuals.Methods: We analyzed two Spanish clinical cohorts (1116 women and 939 elderly individuals) who were studied for suspicion of OSA between 1998 and 2007. A calibration model was used to apply different definitions of hypopnea to our two cohorts. Hypopnea was defined as a 30-90% reduction in oronasal flow for ≥10 s followed by (1) ≥4% fall in oxyhemoglobin saturation-AHI4%; (2) ≥3% fall in oxyhemoglobin saturation-AHI3%; or (3) ≥3% fall in oxyhemoglobin saturation or an event-related arousal-AHI3%a.Results: In both cohorts, the prevalence of an AHI ≥30 events/h increased by 14% with AHI3%a, compared to AHI4% criteria. The percentage of women with an AHI <5 events/h decreased from 13.9% with AHI4% to 1.1% with the AHI3%a definition. In fully adjusted multivariable analyses, AHI ≥30 events/h was associated with increased cardiovascular mortality risk in women, regardless of the hypopnea definition, and in elderly individuals diagnosed using the AHI4% and AHI3% but not the AHI3%a definition.Conclusions: Our findings suggest that hypopnea definitions substantially influence OSA prevalence and severity classification, and also affect the association with cardiovascular outcomes. With the currently recommended criterion (AHI3%a), a threshold of 30 events/h is appropriate to identify women, but not elderly individuals with increased risk of cardiovascular death. [ABSTRACT FROM AUTHOR]

Postural instability and falls are commonly seen because of aging and motor disabilities. This study aims to assess the posture-related changes in brain functional connectivity by wavelet phase coherence (WPCO) of oxyhemoglobin concentration change (Δ[HbO 2 ]) signals measured through near-infrared spectroscopy (NIRS) in elderly subjects. The NIRS signals were continuously recorded from the prefrontal cortex and sensorimotor cortical areas in 39 healthy elderly subjects and 22 young healthy subjects during 20 min resting and 10 min standing states. Eight connection types were obtained from the recorded brain areas. The WPCO were calculated in five frequency intervals in each channel pair as follows: I, 0.6–2 Hz; II, 0.145–0.6 Hz; III, 0.052–0.145 Hz; IV, 0.021–0.052 Hz; and V, 0.0095–0.021 Hz. Results show that posture change and age significantly interacts with the right prefrontal cortex (PFC) and left sensorimotor cortex (SMC) connectivity in interval V (F = 5.010, p = 0.028). The left and right PFC connectivity in interval I, the left and right SMC connectivity in interval IV, and the connectivity in interval V, including right PFC and right SMC connectivity, left PFC and left SMC connectivity, and right PFC and left SMC connectivity, showed a significant difference between the Group Elderly and Group Young in response to posture change (p < 0.05). This study provides new insight into the mechanism of posture control, and results may be useful in assessing the risk of postural instability in aged persons. [ABSTRACT FROM AUTHOR]

Background Understanding of cortico-cortical activity in eloquent areas intraoperatively is crucial for neurosurgical procedures. Here, we used intraoperative near-infrared spectroscopy (iNIRS) during direct cortical stimulation as a robust tool to better understand the cortico-cortical connectivity in language systems. Methods We applied iNIRS to 3 patients who underwent epilepsy surgery due to lesions (cavernous angioma, epidermoid cyst, and low-grade glioma) located in language areas. Using iNIRS, we measured the blood concentration changes of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) in the lateral temporal cortex during direct cortical stimulation (50 Hz) at the inferior frontal area where Broca’s area was probabilistically located. Results In all patients, 50 Hz stimulation elicited hemodynamic changes in the superior temporal gyrus (STG). During 0.8–4.8 s after stimulation, HbO2 increased and HbR decreased in the posterior part of the STG (Wernicke’s area). Similar responses were observed in the anterior part of the STG 1.3–8.0 s after stimulation. Finally, these changes were disappeared in the middle temporal gyrus. Conclusions Our results suggest that cortical stimulation of Broca’s area elicits hemodynamic responses in Wernicke's area via cortico-cortical connectivity. We demonstrated cortico-cortical evoked responses in language systems using iNIRS during direct cortical stimulation. Our iNIRS data will provide useful information about cortico-cortical networks underlying human brain functions intraoperatively and will contribute to neurosurgical treatment in eloquent areas. [ABSTRACT FROM AUTHOR]

Background Air pollution exposure could mitigate the health benefits of exercise in patients with heart failure (HF). We tested the effects of a respiratory filter on HF patients exposed to air pollution during exercise. Methods and Results Ancillary analysis of the FILTER-HF trial, focused on the exercise outcomes. In a randomized, double-blind, 3-way crossover design, 26 HF patients and 15 control volunteers were exposed to clean air, unfiltered dilute diesel engine exhaust (DE), or filtered DE for 6 min during a submaximal cardiopulmonary testing in a controlled-exposure facility. Prospectively collected data included six-minute walking test [6mwt], VO 2 , VE/VCO 2 Slope, O 2 Pulse, pulmonary ventilation [VE], tidal volume, VD/Vt, oxyhemoglobin saturation and CO2-rebreathing. Compared to clean air, DE adversely affected VO 2 (11.0 ± 3.9 vs. 8.4 ± 2.8 ml/kg/min; p < 0.001); 6mwt (243.3 ± 13.0 vs. 220.8 ± 13.7 m; p = 0.030); and O 2 Pulse (8.9 ± 1.0 vs. 7.8 ± 0.7 ml/beat; p < 0.001) in HF patients. Compared to DE, filtration reduced the particulate concentration from 325 ± 31 to 25 ± 6 μg/m 3 , and was associated with an increase in VO 2 (10.4 ± 3.8 ml/kg/min; p < 0.001 vs. DE) and O 2 Pulse (9.7 ± 1.1 ml/beat; p < 0.001 vs. DE) in patients with HF. Filtration was associated with higher VE and CO 2 -rebreathing in both groups. VE/VCO 2 Slope was higher among patients with HF. Conclusion DE adversely affects exercise capacity in patients with HF. A simple respiratory filter can reduce the adverse effects of pollution on VO 2 and O 2 Pulse. Given the worldwide prevalence of exposure to traffic-related air pollution, these findings are relevant for public health especially in this highly susceptible population. The filter intervention holds great promise that needs to be tested in future studies. [ABSTRACT FROM AUTHOR]

In this paper, we apply support vector machine (SVM) based classification of functional near-infrared spectroscopy (fNIRS) which is non-invasive monitoring of human brain function by measuring the changes in the concentration of oxyhemoglobin and deoxyhemoglobin. Data collected from 11 healthy volunteers and 16 schizophrenia subjects. Signals were first preprocessed and decomposed by using discrete wavelet transform DWT to eliminate systemic physiological interference. A preliminary analysis based on Genetic Algorithm (GA) favored eight channels of the reconstructed fNIRS signals for further analysis. Energy in these 8 reconstructed signals was computed and used for classification of signals. SVM based classifier was employed to diagnosis schizophrenia. The results show the promising classification accuracy of nearly 84% in detection of schizophrenia from healthy subjects. The major finding of this study is that selected channels were able to identify differences in functional connectivity patterns of prefrontal cortex (PFC) elicited by Stroop task. [ABSTRACT FROM AUTHOR]

Background Oxyhemoglobin-sensitive sequences, namely T2*, can indirectly depict changes in oxygen extraction. Purpose of this study was to investigate the dynamics of T2* changes in ischemic tissue. New method We investigated earliest temporo-spatial dynamics within ischemic tissue, measured with quantitative T2* imaging in the histologically defined infarct core and surrounding surviving tissue. Middle cerebral artery occlusion (MCAO) was induced by a filament model in mice. Serial multiple gradient-echo T2* sequences and diffusion-weighted images were acquired for 60 min after MCAO and repeated for 60 min after recanalization. T2* maps were co-registered with histology and T2* changes were compared to the contralateral hemisphere. Results Within the histologically defined infarct core, relative T2* values decreased significantly by −10.8 ± 2.8% ( P = 0.003) compared to the contralateral hemisphere within 3.5 ± 0.7 min after MCAO. Relative T2* values in volume exceeding the histologically determined infarct core were significantly less decreased (−6.7 ± 2.1%; P = 0.02) and increased after recanalization (+3.9 ± 1.9%; P = 0.045). Volume with T2* decrease showed continuous growth over 60 min after MCAO ( P = 0.002) and decreased during 60 min after recanalization ( P = 0.026), showing most significant correlations between infarct core volume and T2* abnormality volume ( r = 0.66; P = 0.037) of the last image acquired after recanalization. Comparison with existing method(s) To our best knowledge, this is the first application of non-invasive quantitative T2* measurements to assess changes in levels of deoxyhemoglobin as an indirect biomarker for metabolic impairment in ischemic tissue. Conclusions Quantitative T2* imaging might be a feasible tool to indicate change of oxygenation in acute stroke imaging, without administration of contrast agent. [ABSTRACT FROM AUTHOR]

For the ( S  = 0 electron-spin) Fe O 2 bonding of an oxyheme, use of the McClure (O 2 , S  = 1 electron spin) valence bond structure rather than the Weiss (O 2 (−) , S  = ½ electron spin) valence bond structure accounts for the formation of the products in the heme O 2  + NO → heme (+)  + NO 3 (−) reaction. [ABSTRACT FROM AUTHOR]

Here we show that methemoglobin is converted to oxyhemoglobin in the presence of perfluorocarbon (PFС) emulsion. Methemoglobin in blood at the level of above 30% can cause severe complications and lethal outcome. Some pharm chemicals in blood in vivo and in vitro can lead to oxidation of iron, Fe 2+ → Fe 3+ , and to increased level of methemoglobin. The oxidized heme is not able to carry oxygen, hypoxia arises and irreversible changes are developing in vital organs. We added NaNO 2 solution in different concentrations to blood in vitro in order to yield methemoglobin. Then the suspension of PFC nanoparticles was added. As methemoglobin interacted with PFC nanoparticles the optical density of peaks typical for oxyhemoglobin increased and spectral peak of methemoglobin decreased. The greater the concentration of PFC and the more was the incubation time, the more efficient was the process of reduction of methemoglobin to oxyhemoglobin. We proved experimentally that with an initial concentration of methemoglobin ​in average 95% the addition of nanoparticles of PFC decreases its concentration to 9% ​in average. At the same time the concentration of oxyhemoglobin increased in average from 5% to 81%. [ABSTRACT FROM AUTHOR]

Curcumin (CCM) is a natural polyphenolic compound in Curcuma longa that has been reported to exhibit neuroprotective effects. Subarachnoid hemorrhage (SAH) is a severe neurological disorder with an unsatisfactory prognosis. Oxyhemoglobin (OxyHb) plays an important role in mediating the neurological deficits following SAH. The present study, therefore, aimed to investigate the effect of CCM on primary cortical neurons exposed to OxyHb neurotoxicity. Cortical neurons were exposed to OxyHb at a concentration of 10 μM in the presence or absence of 5 μM (low dose) or 10 μM (high dose) CCM for 24 h. Morphological changes in the neurons were observed. Cell viability and lactate dehydrogenase (LDH) release were assayed to determine the extent of cell injury. Additionally, levels of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and reactive oxygen species (ROS) were measured. Neuronal apoptosis was assayed via TUNEL staining and protein levels of cleaved caspase-3, Bax, and Bcl-2 were measured by Western blot. Levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6 were measured using ELISA kits. Our results suggested that CCM at both low and high doses markedly improved cell viability and decreased LDH release. CCM treatment decreased neuronal apoptosis. Additionally, oxidative stress and inflammation induced by OxyHb were alleviated by CCM treatment. In conclusion, CCM inhibits neuronal apoptosis, and alleviates oxidative stress and inflammation in neurons subjected to OxyHb, suggesting that it may be beneficial in the treatment of brain damage following SAH. [ABSTRACT FROM AUTHOR]

The reaction of oxyhemoglobin with nitric oxide is known to occur in vivo , with direct medical and pathophysiological relevance. The mechanism has been proposed to involve a transient iron(III)-peroxynitrite intermediate, the formation of which would be rate-limiting and the decay of which would yield iron(III)-aqua/iron(III)-hydroxo hemoglobin. Reported here are rapid-freeze-quench EPR (RFQ-EPR) spectroscopy data on the reaction of oxyhemoglobin with nitric oxide; no direct evidence is seen for an iron(III)-peroxynitrite intermediate. These findings are consistent with theoretical considerations according to which such an intermediate does form but is too short-lived to be detectable. Instead, iron(III) low-spin and high-spin transient species are detected in the RFQ-EPR experiments, which can be explained as arising from interactions of nitrate with methemoglobin. [ABSTRACT FROM AUTHOR]

Herein we utilized the filter paper to physically trap red blood cells (RBC) to observe the breathing process of red blood cells based on the permeability of the filter paper. By integrating double-sided conductive carbon tape as the working electrodes, the device could be applied to monitor electrochemical responses of RBC for up to hundreds of minutes. The differential pulse voltammetry (DPV) peak currents increased under oxygen while decreased under nitrogen, indicating that RBC could take in and release oxygen. Further studies demonstrated that the RBC suspension could more effectively take in oxygen than the solution of hemoglobin and the supernatant of RBC, suggesting the natural advantage of RBC on oxygen transportation. This study implied that simple paper-based analytical devices might be effectively applied in the study of gas-participating reactions and biochemical detections. [ABSTRACT FROM AUTHOR]

This study aims to assess the dynamic cerebral autoregulation (dCA) in response to posture change using wavelet phase coherence (WPCO) of cerebral tissue oxyhemoglobin concentrations (Delta [HbO 2 ]) and arterial blood pressure (ABP) signals in healthy elderly subjects. Continuous recordings of near-infrared spectroscopy (NIRS) and ABP signals were obtained from simultaneous measurements in 16 healthy elderly subjects (age: 68.9 ± 7.1 years) and 19 young subjects (age: 24.9 ± 3.2 years). The phase coherence between Delta [HbO 2 ] and ABP oscillations in six frequency intervals (I, 0.6–2 Hz; II, 0.15–0.6 Hz; III, 0.05–0.15 Hz; IV, 0.02–0.05 Hz, V, 0.0095–0.02 Hz and VI, 0.005–0.0095 Hz) was analyzed using WPCO. The sit-to-stand posture change induces significantly lower WPCO in interval III ( F = 5.50 p = 0.025) in the elderly subjects than in the young subjects. However, the stand-to-sit posture change induces higher WPCO in intervals II ( F = 5.25 p = 0.028) and V ( F = 6.22 p = 0.018) in the elderly subjects than in the young subjects. The difference of WPCO in response to posture change between the elderly and the young subjects indicates an altered CA due to aging. This study provides new insight into the dynamics of CA and may be useful in identifying the risk for dCA processes. [ABSTRACT FROM AUTHOR]

The current studies have investigated the effect of heterocyclic drugs with the single thiol group (thiamazole, mercaptopurine) and dithiol aliphatic drugs (dimercaptosuccinic acid, dithiothreitol) under oxidative stress conditions, using tert -butyl hydroperoxide ( t -BuOOH), in human erythrocyte lysate with the luminol-enhanced chemiluminescence technique. Knowing that oxidative processes induced by t -BuOOH are triggered by (oxy)hemoglobin (Hb), the effect of different thiol drugs (RSH) on isolated human Hb oxidation to methemoglobin (MHb) and hemichromes (HChr) was further considered. Three types of chemiluminescence curves, fitting to logistic-exponential model, have been revealed under influence of RSH. Structure of the data (MHb and HChr production, and free radical activity of RSH) in Principal Component Analysis visualization and kinetic profiles of chemiluminescence integrate information in terms of the diversity of RSH reaction mechanisms depending on the specific molecular context of the given thiol: aliphatic or aromatic nature as well as the number and position of the –SH groups in the molecule. The study conducted in presented in vitro systems indicates the potential role of thiol drugs mediated toxicity in an oxidative stress dependent mechanism. [ABSTRACT FROM AUTHOR]

Galectins are mammalian lectins established to play a crucial role in the progression of various cancer types by the virtue of their differential expression in normal and cancerous cells. In the present study, goat heart galectin-1 (GHG-1) was purified and investigated for its potential role in the detection of post-malignant changes in glycosylation pattern. When exposed to superoxide radicals generated from a pyrogallol auto-oxidation system, GHG-1 treated erythrocyte suspension released higher amount of oxyhemoglobin than the unagglutinated erythrocytes. The extent of erythrocyte hemolysis was found to be directly proportional to concentrations of hypochlorous acid. GHG-1 was used to detect the change in the β -galactoside expression pattern in erythrocyte membrane from human donors suffering from prostate and breast cancer. No significant change was observed in the hemolysis of lectin agglutinated erythrocytes collected from pre-operated breast cancer patients, whereas significant increase was observed in normal healthy control and post-operated samples. Findings of this study proclaim GHG-1 as an important tool for the detection of post-malignant changes in glycosylation pattern. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is an endogenously generated and putative signaling/effector molecule. Despite its numerous reported functions, the chemistry by which it elicits its functions is not understood. Moreover, recent studies allude to the existence of other sulfur species besides H 2 S that may play critical physiological roles. Herein, the basic chemical biology of H 2 S as well as other related or derived species is discussed and reviewed. This review particularly focuses on the per- and polysulfides which are likely in equilibrium with free H 2 S and which may be important biological effectors themselves. [ABSTRACT FROM AUTHOR]

Perfusion-based changes in MR signal intensity can occur in response to the introduction of exogenous contrast agents and endogenous tissue properties (e.g. blood oxygenation). MR measurements aimed at capturing these changes often implement single-shot echo planar imaging (ssEPI). In recent years ssEPI readouts have been combined with parallel imaging (PI) to allow fast dynamic multi-slice imaging as well as the incorporation of multiple echoes. A multiple spin- and gradient-echo (SAGE) EPI acquisition has recently been developed to allow measurement of transverse relaxation rate ( R 2 and R 2 ⁎ ) changes in dynamic susceptibility contrast (DSC)-MRI experiments in the brain. With SAGE EPI, the use of PI can influence image quality, temporal resolution, and achievable echo times. The effect of PI on dynamic SAGE measurements, however, has not been evaluated. In this work, a SAGE EPI acquisition utilizing SENSE PI and partial Fourier (PF) acceleration was developed and evaluated. Voxel-wise measures of R 2 and R 2 ⁎ in healthy brain were compared using SAGE EPI and conventional non-EPI multiple echo acquisitions with varying SENSE and PF acceleration. A conservative SENSE factor of 2 with PF factor of 0.73 was found to provide accurate measures of R 2 and R 2 ⁎ in white (WM) ( r R2 = [0.55–0.79], r R2⁎ = [0.47–0.71]) and gray (GM) matter ( r R2 = [0.26–0.59], r R2⁎ = [0.39–0.74]) across subjects. The combined use of SENSE and PF allowed the first dynamic SAGE EPI measurements in muscle, with a SENSE factor of 3 and PF factor of 0.6 providing reliable relaxation rate estimates when compared to multi-echo methods. Application of the optimized SAGE protocol in DSC-MRI of high-grade glioma patients provided T 1 leakage-corrected estimates of CBV and CBF as well as mean vessel diameter (mVD) and simultaneous measures of DCE-MRI parameters K trans and v e . Likewise, application of SAGE in a muscle reperfusion model allowed dynamic measures of R 2 ′, a parameter that has been shown to correlate with muscle oxy-hemoglobin saturation. [ABSTRACT FROM AUTHOR]

This study quantified the inter- and intra-test reliability of telemetric surface electromyography (EMG) and near infrared spectroscopy (NIRS) during resistance exercise. Twelve well-trained young men performed high-intensity back squat exercise (12 sets at 70–90% 1-repetition maximum) on two occasions, during which EMG and NIRS continuously monitored muscle activation and oxygenation of the thigh muscles. Intra-test reliability for EMG and NIRS variables was generally higher than inter-test reliability. EMG median frequency variables were generally more reliable than amplitude-based variables. The reliability of EMG measures was not related to the intensity or number of repetitions performed during the set. No notable differences were evident in the reliability of EMG between different agonist muscles. NIRS-derived measures of oxyhaemoglobin, deoxyhaemoglobin and tissue saturation index were generally more reliable during single-repetition sets than multiple-repetition sets at the same intensity. Tissue saturation index was the most reliable NIRS variable. Although the reliability of the EMG and NIRS measures varied across the exercise protocol, the precise causes of this variability are not yet understood. However, it is likely that biological variation during multi-joint isotonic resistance exercise may account for some of the variation in the observed results. [ABSTRACT FROM AUTHOR]

Background In clinical practice, global oxygen delivery (DO2) is often considered as a whole; however pathological and adaptive responses after a decrease in individual constituents of the DO2 equation (cardiac output, haemoglobin, oxyhaemoglobin saturation) are likely to be diverse. We hypothesized that an equivalent decrease in DO2 after reductions in each separate component of the equation would result in different haemodynamic, tissue oxygenation, and stress hormonal responses. Methods Anaesthetized, fluid-resuscitated male Wistar rats were subjected to circulatory, anaemic, or hypoxic hypoxia (by haemorrhage, isovolaemic haemodilution, and breathing a hypoxic gas mix, respectively), produced either rapidly over 5 min or graded over 30 min, to a targeted 50% decrease in global oxygen delivery. Sham-operated animals acted as controls. Measurements were made of haemodynamics, skeletal muscle tissue oxygen tension, blood gas analysis, and circulating stress hormone levels. Results Whereas haemorrhage generated the largest decrease in cardiac output, and the greatest stress hormone response, haemodilution had the most marked effect on arterial pressure. In contrast, rapid hypoxaemia produced a minor impact on global haemodynamics yet induced the greatest decrease in regional oxygenation. A greater degree of hyperlactataemia was observed with graded insults compared with those administered rapidly. Conclusions Decreasing global oxygen delivery, achieved by targeted reductions in its separate components, induces varying circulatory, tissue oxygen tension, and stress hormone responses. We conclude that not all oxygen delivery is the same; this disparity should be emphasized in classical teaching and re-evaluated in patient management. [ABSTRACT FROM PUBLISHER]

The objective of this investigation was to evaluate the effects of l-histidine on the stability of porcine hemoglobin concentrates during storage. The results indicated that the addition of l histidine increased the oxyhemoglobin content and a* values but decreased the methemoglobin content and free iron content (P<0.05) during storage. The addition of iron cation decreased both the oxyhemoglobin content and a* values but increased both the methemoglobin content and free iron concentration (P<0.05). CD spectra revealed that the free iron content induced the transformation of the hemoglobin secondary structure from an ॅ-helix (close structure) to a β-pleated, β-turn, and random coil arrangement (loose structure), while l-histidine weakened this behavior of the free iron. Infrared spectra demonstrated that the l-histidine coordinated with the free iron (Fe2+ or Fe3+) to give the corresponding complex at 25°C and pH7.3. Therefore, :small-caps>l-histidine enhanced the stability of hemoglobin concentrates by coordinating with free iron. [ABSTRACT FROM AUTHOR]

Background The nasal ala is an attractive site for pulse oximetry because of perfusion by branches of the external and internal carotid arteries. We evaluated the accuracy of a novel pulse oximetry sensor custom designed for the nasal ala. Methods After IRB approval, healthy non-smoking subjects [n=12; aged 28 (23–41) yr; 6M/6F] breathed hypoxic mixtures of fresh gas by a facemask to achieve oxyhaemoglobin saturations of 70–100% measured by traditional co-oximetry from radial artery samples. Concurrent alar and finger pulse oximetry values were measured using probes designed for these sites. Data were analysed using the Bland–Altman method for multiple observations per subject. Results Bias, precision, and accuracy root mean square error (ARMS) over a range of 70–100% were significantly better for the alar probe compared with a standard finger probe. The mean bias for the alar and finger probes was 0.73% and 1.90% (P<0.001), respectively, with corresponding precision values of 1.65 and 1.83 (P=0.015) and ARMS values of 1.78% and 2.72% (P=0.047). The coefficients of determination were 0.96 and 0.96 for the alar and finger probes, respectively. The within/between-subject variation for the alar and finger probes were 1.14/1.57% and 1.87/1.47%, respectively. The limits of agreement were 3.96/−2.50% and 5.48/−1.68% for the alar and finger probes, respectively. Conclusions Nasal alar pulse oximetry is feasible and demonstrates accurate pulse oximetry values over a range of 70–100%. The alar probe demonstrated greater accuracy compared with a conventional finger pulse oximeter. [ABSTRACT FROM AUTHOR]

Abstract: The primary goal of most cochlear implant procedures is to improve a patient's ability to discriminate speech. To accomplish this, cochlear implants are programmed so as to maximize speech understanding. However, programming a cochlear implant can be an iterative, labor-intensive process that takes place over months. In this study, we sought to determine whether functional near-infrared spectroscopy (fNIRS), a non-invasive neuroimaging method which is safe to use repeatedly and for extended periods of time, can provide an objective measure of whether a subject is hearing normal speech or distorted speech. We used a 140 channel fNIRS system to measure activation within the auditory cortex in 19 normal hearing subjects while they listed to speech with different levels of intelligibility. Custom software was developed to analyze the data and compute topographic maps from the measured changes in oxyhemoglobin and deoxyhemoglobin concentration. Normal speech reliably evoked the strongest responses within the auditory cortex. Distorted speech produced less region-specific cortical activation. Environmental sounds were used as a control, and they produced the least cortical activation. These data collected using fNIRS are consistent with the fMRI literature and thus demonstrate the feasibility of using this technique to objectively detect differences in cortical responses to speech of different intelligibility. [Copyright &y& Elsevier]

Abstract: Airway lining fluid contains relatively high concentrations of nitrite, and arterial blood levels of nitrite are higher than venous levels, suggesting the lung epithelium may represent an important source of nitrite in vivo. To investigate whether lung epithelial cells possess the ability to convert NO to nitrite by oxidation, and the effect of oxygen reactions on nitrite formation, the NO donor DETA NONOate was incubated with or without A549 cells or primary human bronchial epithelial (HBE) cells for 24 h under normoxic (21% O2) and hypoxic (1% O2) conditions. Nitrite production was significantly increased under all conditions in the presence of A549 or HBE cells, suggesting that both A549 and HBE cells have the capacity to oxidize NO to nitrite even under low-oxygen conditions. The addition of oxyhemoglobin to the A549 cell medium decreased the production of nitrite, consistent with NO scavenging limiting nitrite formation. Heat-denatured A549 cells produced much lower nitrite and nitrate, suggesting an enzymatic activity is required. This NO oxidation activity was highest in membrane-bound proteins with molecular size <100kDa. In addition, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one and cyanide inhibited formation of nitrite in A549 cells. It has been shown that ceruloplasmin (Cp) possesses an NO oxidase and nitrite synthase activity in plasma based on NO oxidation to nitrosonium cation. We observed that Cp is expressed intracellularly in lung epithelial A549 cells and secreted into the medium under basal conditions and during cytokine stimulation. However, an analysis of Cp expression level and activity measured via p-phenylenediamine oxidase activity assay revealed very low activity compared with plasma, suggesting that there is insufficient Cp to contribute to detectable NO oxidation to nitrite in A549 cells. Additionally, Cp levels were knocked down using siRNA by more than 75% in A549 cells, with no significant change in either nitrite or cellular S-nitrosothiol formation compared to scrambled siRNA control under basal conditions or cytokine stimulation. These data suggest that lung epithelial cells possess NO oxidase activity, which is enhanced in cell-membrane-associated proteins and not regulated by intracellular or secreted Cp, indicating that alternative NO oxidases determine hypoxic and normoxic nitrite formation from NO in human lung epithelial cells. [Copyright &y& Elsevier]