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Journal of Inorganic Biochemistry Jun 2020Lucina pectinata live in high concentrations of hydrogen sulfide (HS) and contains one hemoglobin, Hemoglobin I (HbI), transporting HS and two hemoglobins, Hemoglobin II...
Lucina pectinata live in high concentrations of hydrogen sulfide (HS) and contains one hemoglobin, Hemoglobin I (HbI), transporting HS and two hemoglobins, Hemoglobin II (HbII) and Hemoglobin (HbIII), transferring dioxygen to symbionts. HbII and HbIII contain B10 tyrosine (Tyr) and E7 glutamine (Gln) in the heme pocket generating an efficient hydrogen bonding network with the (HbII-HbIII)-O species, leading to very low ligand dissociation rates. The results indicate that the oxy-hemeprotein is susceptible to pH from 4 to 9, at acidic conditions, and as a function of the potassium ferricyanide concentration, 100% of the met-aquo derivative is produced. Without a strong oxidant, pH 5 generates a small concentration of the met-aquo complex. The process is accelerated by the presence of salts, as indicated by the crystallization structures and UV-Vis spectra. The results suggest that acidic pH generates conformational changes associated with B10 and E7 heme pocket amino acids, weakening the (HbII-HbIII)-O hydrogen bond network. The observation is supported by X-ray crystallography, since at pH 4 and 5, the heme-Fe tends to oxidize, while at pH 7, the oxy-heterodimer is present. Conformational changes also are observed at higher pH by the presence of a 605 nm transition associated with the iron heme-Tyr interaction. Therefore, pH is one crucial factor regulating the (HbII-HbIII)-O complex hydrogen-bonding network. Thus, it can be proposed that the hydrogen bonding adjustments between the heme bound O and the Tyr and Gln amino acids contribute to oxygen dissociation from the (HbII-HbIII)-O system.
Topics: Animals; Bivalvia; Crystallography, X-Ray; Dimerization; Glutamine; Heme; Hemeproteins; Hemoglobins; Hydrogen Bonding; Hydrogen Sulfide; Hydrogen-Ion Concentration; Ligands; Oxygen; Oxyhemoglobins; Protein Conformation; Tyrosine
PubMed: 32217352
DOI: 10.1016/j.jinorgbio.2020.111055 -
Scientific Reports Jan 2022Hemoglobin is one of the most widely studied proteins genetically, biochemically, and structurally. It is an oxygen carrying tetrameric protein that imparts the... (Comparative Study)
Comparative Study
Hemoglobin is one of the most widely studied proteins genetically, biochemically, and structurally. It is an oxygen carrying tetrameric protein that imparts the characteristic red color to blood. Each chain of hemoglobin harbors a heme group embedded in a hydrophobic pocket. Several studies have investigated structural variations present in mammalian hemoglobin and their functional implications. However, camel hemoglobin has not been thoroughly explored, especially from a structural perspective. Importantly, very little is known about how the heme group interacts with hemoglobin under varying conditions of osmolarity and temperature. Several experimental studies have indicated that the tense (T) state is more stable than the relaxed (R) state of hemoglobin under normal physiological conditions. Despite the fact that R state is less stable than the T state, no extensive structural dynamics studies have been performed to investigate global quaternary transitions of R state hemoglobin under normal physiological conditions. To evaluate this, several 500 ns all-atom molecular dynamics simulations were performed to get a deeper understanding of how camel hemoglobin behaves under stress, which it is normally exposed to, when compared to human hemoglobin. Notably, camel hemoglobin was more stable under physiological stress when compared to human hemoglobin. Additionally, when compared to camel hemoglobin, cofactor-binding regions of hemoglobin also exhibited more fluctuations in human hemoglobin under the conditions studied. Several differences were observed between the residues of camel and human hemoglobin that interacted with heme. Importantly, distal residues His58 of α hemoglobin and His63 of β hemoglobin formed more sustained interactions, especially at higher temperatures, in camel hemoglobin. These residues are important for oxygen binding to hemoglobin. Thus, this work provides insights into how camel and human hemoglobin differ in their interactions under stress.
Topics: Animals; Binding Sites; Camelus; Heat-Shock Response; Hemoglobins; Humans; Molecular Dynamics Simulation; Oxygen; Oxyhemoglobins; Protein Binding; Protein Stability; Protein Structure, Quaternary; Salt Stress; Species Specificity; Structure-Activity Relationship
PubMed: 34997093
DOI: 10.1038/s41598-021-04112-y -
The Journal of Physiology Sep 2017Cerebral haemodynamic response to neural stimulation has been extensively studied in adults, but little is known about cerebral haemodynamic response in the fetal and...
KEY POINTS
Cerebral haemodynamic response to neural stimulation has been extensively studied in adults, but little is known about cerebral haemodynamic response in the fetal and neonatal brain. The present study describes the cerebral haemodynamic response measured by near infrared spectroscopy to somatosensory stimulation in newborn lambs, in comparison to recent findings in fetal sheep. The cerebral haemodynamic responses in the newborn lamb brain can involve an increase in oxyhaemoglobin (oxyHb), or a decrease of oxyHb suggestive of reduced perfusion and oxygenation. Positive correlations between changes in oxyHb and mean arterial blood pressure were found in newborn but not fetal sheep, which suggests the result is unlikely to be due to immature autoregulation alone. In contrast to adult studies, hypercapnia increased the changes in cerebral blood flow and oxyHb in most of the lambs in response to somatosensory stimulation.
ABSTRACT
The neurovascular coupling response has been defined for the adult brain, but in the neonate non-invasive measurement of local cerebral perfusion using near infrared spectroscopy or blood oxygen level-dependent functional magnetic resonance imaging have yielded variable and inconsistent results, including negative responses suggesting decreased perfusion and localized tissue tissue hypoxia. Also, the impact of permissive hypercapnia (P aC O2 > 50 mmHg) in the management of neonates on cerebrovascular responses to somatosensory input is unknown. Using near infrared spectroscopy to measure changes in cerebral oxy- and deoxyhaemoglobin (ΔoxyHb, ΔdeoxyHb) in eight anaesthetized newborn lambs, we studied the cerebral haemodynamic functional response to left median nerve stimulation using stimulus trains of 1.8, 4.8 and 7.8 s. Stimulation always produced a somatosensory evoked response, and superficial cortical perfusion measured by laser Doppler flowmetry predominantly increased following median nerve stimulation. However, with 1.8 s stimulation, oxyHb responses in the contralateral hemisphere were either positive (i.e. increased oxyHb), negative, or absent; and with 4.8 and 7.8 s stimulations, both positive and negative responses were observed. Hypercapnia increased baseline oxyHb and total Hb consistent with cerebral vasodilatation, and six of seven lambs tested showed increased Δtotal Hb responses after the 7.8 s stimulation, among which four lambs also showed increased ΔoxyHb responses. In two of three lambs, the negative ΔoxyHb response became a positive pattern during hypercapnia. These results show that instead of functional hyperaemia, somatosensory stimulation can evoke negative (decreased oxyHb, total Hb) functional responses in the neonatal brain suggestive of decreased local perfusion and vasoconstriction, and that hypercapnia produces both baseline hyperperfusion and increased functional hyperaemia.
Topics: Animals; Animals, Newborn; Arterial Pressure; Brain; Electric Stimulation; Evoked Potentials, Somatosensory; Forelimb; Hemoglobins; Hypercapnia; Median Nerve; Oxyhemoglobins; Sheep; Spectroscopy, Near-Infrared
PubMed: 28643877
DOI: 10.1113/JP274244 -
The Journal of Biological Chemistry Apr 2008The nitrite anion (NO(-)(2)) has recently received much attention as an endogenous nitric oxide source that has the potential to be supplemented for therapeutic benefit....
The nitrite anion (NO(-)(2)) has recently received much attention as an endogenous nitric oxide source that has the potential to be supplemented for therapeutic benefit. One major mechanism of nitrite reduction is the direct reaction between this anion and the ferrous heme group of deoxygenated hemoglobin. However, the reaction of nitrite with oxyhemoglobin (oxyHb) is well established and generates nitrate and methemoglobin (metHb). Several mechanisms have been proposed that involve the intermediacy of protein-free radicals, ferryl heme, nitrogen dioxide (NO(2)), and hydrogen peroxide (H(2)O(2)) in an autocatalytic free radical chain reaction, which could potentially limit the usefulness of nitrite therapy. In this study we show that none of the previously published mechanisms is sufficient to fully explain the kinetics of the reaction of nitrite with oxyHb. Based on experimental data and kinetic simulation, we have modified previous models for this reaction mechanism and show that the new model proposed here is consistent with experimental data. The important feature of this model is that, whereas previously both H(2)O(2) and NO(2) were thought to be integral to both the initiation and propagation steps, H(2)O(2) now only plays a role as an initiator species, and NO(2) only plays a role as an autocatalytic propagatory species. The consequences of uncoupling the roles of H(2)O(2) and NO(2) in the reaction mechanism for the in vivo reactivity of nitrite are discussed.
Topics: Anions; Free Radicals; Heme; Humans; Hydrogen Peroxide; Kinetics; Methemoglobin; Models, Chemical; Nitrates; Nitrites; Oxidation-Reduction; Oxyhemoglobins
PubMed: 18203719
DOI: 10.1074/jbc.M705630200 -
Complementary Therapies in Medicine Dec 2017The present study aimed to clarify the effects of viewing fresh roses on prefrontal cortex activity, autonomic nervous activity and subjective assessments of...
OBJECTIVES
The present study aimed to clarify the effects of viewing fresh roses on prefrontal cortex activity, autonomic nervous activity and subjective assessments of psychological relaxation.
DESIGN
A crossover design, in which each experimental group crosses over from one treatment to another, was used.
SETTING AND INTERVENTIONS
A total of 15 female university students (mean age 21.7±1.1years) viewed fresh roses for 3min; the control consisted of no experimental stimulus.
MAIN OUTCOME MEASURES
Physiological effects on prefrontal cortex activity were determined by near-infrared time-resolved spectroscopy, which was assessed by measuring oxyhemoglobin (oxy-Hb) concentration in the left and right prefrontal cortex; effects on autonomic nervous activity were assessed by measuring heart rate variability (HRV) and heart rate. Modified semantic differential method and Profile of Mood States were used to determine subjective evaluations.
RESULTS
Viewing roses induced: 1) a significant decrease in oxy-Hb concentrations in the right prefrontal cortex; 2) a marginally significant decrease in ln[LF/(LF+HF)] of HRV, which is associated with sympathetic nervous activity; 3) a significant increase in perceptions of feeling 'comfortable,' 'relaxed,' and 'natural;' and 4) a significant improvement in mood state.
CONCLUSIONS
These findings indicate that visual stimulation with roses induces physiological and psychological relaxation.
Topics: Adult; Affect; Autonomic Nervous System; Environment; Female; Flowers; Heart Rate; Humans; Oxyhemoglobins; Prefrontal Cortex; Relaxation; Rosa; Vision, Ocular; Young Adult
PubMed: 29154072
DOI: 10.1016/j.ctim.2017.10.001 -
European Journal of Medical Research Mar 2024Hyperspectral techniques have aroused great interest in non-invasively measuring periodontal tissue hemodynamics. However, current studies mainly focused on three...
BACKGROUND
Hyperspectral techniques have aroused great interest in non-invasively measuring periodontal tissue hemodynamics. However, current studies mainly focused on three typical inflammation stages (healthy, gingivitis and periodontitis) and practical approaches for using optical spectroscopy for early and precisely detection of periodontal inflammation at finer disease stages have not been well studied.
METHODS
This study provided novel spectroscopic insights into periodontitis at different stages of disease, and developed six simple but physically meaning hemodynamic spectral indices (HSIs) including four spectral absorption depths of oxyhemoglobin ( ), deoxyhemoglobin ( ), total hemoglobin ( ) and tissue water ( ), and two normalized difference indices of oxyhemoglobin( ) and deoxyhemoglobin ( ) from continuum-removal spectra (400-1700 nm) of periodontal tissue collected from 47 systemically healthy subjects over different severities from healthy, gingivitis, slight, moderate to severe periodontitis for early and precision diagnostics of periodontitis. Typical statistical analyses were conducted to explore the effectiveness of the proposed HSIs.
RESULTS
and exerted significant increasing trends as inflammation progressed, whereas exhibited significant difference (P < 0.05) from the healthy sites only at moderate and severe periodontitis and presented unstable sensitives to disease severity. By contrast, and showed more steadily downward trends as severity increased, and demonstrated the highest correlations with clinical gold standard parameters. Particularly, the proposed normalized HSIs ( and ) yielded high correlations of - 0.49 and - 0.44 with probing depth, respectively, far outperforming results achieved by previous studies. The performances of the HSIs were also confirmed using the periodontal therapy group.
CONCLUSIONS
These results indicated great potentials of combination optical spectroscopy and smart devices to non-invasively probe periodontitis at earlier stages using the simple and practical HSIs. Trial registration This study was retrospectively registered in the Chinese Clinical Trial Registry on October 24, 2021, and the clinical registration number is ChiCTR2100052306.
Topics: Humans; Oxyhemoglobins; Periodontitis; Gingivitis; Inflammation; Water; Hemodynamics
PubMed: 38528571
DOI: 10.1186/s40001-024-01748-0 -
Journal of Biomedical Optics Mar 2015Due to the various causes of methemoglobinemia and its potential to be confused with other diseases, in vivo measurements of methemoglobin have significant applications...
Due to the various causes of methemoglobinemia and its potential to be confused with other diseases, in vivo measurements of methemoglobin have significant applications in the clinic. Using photoacoustic microscopy (PAM), we quantified the average and the distributed percentage of methemoglobin both in vitro and in vivo. Based on the absorption spectra of methemoglobin, oxyhemoglobin, and deoxyhemoglobin, three wavelengths were chosen to differentiate methemoglobin from the others. The methemoglobin concentrations calculated from the photoacoustic signals agreed well with the preset concentrations. Then we imaged the methemoglobin percentage in microtubes that mimicked blood vessels. Average percentages calculated for five samples with different methemoglobin concentrations also agreed well with the preset values. Finally, we demonstrated the ability of PAM to detect methemoglobin in vivo in a mouse ear. Our results show that PAM can quantitatively image methemoglobin distribution in vivo.
Topics: Animals; Ear Auricle; Hemoglobins; Methemoglobin; Methemoglobinemia; Mice; Microscopy, Acoustic; Oxyhemoglobins; Phantoms, Imaging; Photoacoustic Techniques; Spectrum Analysis
PubMed: 25760655
DOI: 10.1117/1.JBO.20.3.036007 -
Journal of Biomedical Optics Nov 2018We report a near-infrared spectroscopy (NIRS) study of coherent hemodynamic oscillations measured on the human forehead at multiple source-detector distances (1 to...
We report a near-infrared spectroscopy (NIRS) study of coherent hemodynamic oscillations measured on the human forehead at multiple source-detector distances (1 to 4 cm). The physiological source of the coherent hemodynamics is arterial blood pressure oscillations at a frequency of 0.1 Hz, induced by cyclic inflation (to a pressure of 200 mmHg) and deflation of two thigh cuffs wrapped around the subject's thighs. To interpret our results, we use a recently developed hemodynamic model and a phasor representation of the oscillations of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations in the tissue (phasors O, D, and T, respectively). The increase in the phase angle between D and O at larger source-detector separations is assigned to greater flow versus volume contributions and to a stronger blood flow autoregulation in deeper tissue (brain cortex) with respect to superficial tissue (scalp and skull). The relatively constant phase lag of T versus arterial blood pressure oscillations at all source-detector distances was assigned to competing effects from stronger autoregulation and smaller arterial-to-venous contributions in deeper tissue with respect to superficial tissue. We demonstrate the application of a hemodynamic model to interpret coherent hemodynamics measured with NIRS and to assess the different nature of shallow (extracerebral) versus deep (cerebral) tissue hemodynamics.
Topics: Adult; Blood Flow Velocity; Brain; Cerebrovascular Circulation; Female; Forehead; Head; Healthy Volunteers; Hemodynamics; Hemoglobins; Humans; Lasers; Male; Middle Aged; Oscillometry; Oxygen; Oxyhemoglobins; Scalp; Skull; Spectroscopy, Near-Infrared
PubMed: 30444084
DOI: 10.1117/1.JBO.23.12.121615 -
Journal of Biomedical Optics Sep 2022Skin malformations in dermatology are mostly evaluated subjectively, based on a doctor's experience and visual perception; an option for objective quantitative skin...
SIGNIFICANCE
Skin malformations in dermatology are mostly evaluated subjectively, based on a doctor's experience and visual perception; an option for objective quantitative skin assessment is camera-based spectrally selective diagnostics. Multispectral imaging is a technique capable to provide information about concentrations of the absorbing chromophores and their distribution over the malformation in a noncontact way. Conversion of spectral images into distribution maps of chromophores can be performed by means of the modified Beer-Lambert law. However, such distribution maps represent only single specific cases, therefore, some extensive method for data comparison is needed.
AIM
This study aims to develop a more informative approach for identification and characterization of skin malformations using three-dimensional (3D) representation of triple spectral line imaging data.
APPROACH
The 3D-representation method is experimentally tested on eight different skin pathology types, including both benign and malignant pathologies; an imaging device ensuring uniform three laser line (448, 532, and 659 nm) illumination is used. Three spectral line images are extracted from a single snapshot RGB image data, with subsequent calculation of attenuation coefficients for each working wavelength at every image pixel and represented as 3D graphs. Skin chromophore content variations in malformations are represented in a similar way.
RESULTS
Clinical measurement results for 99 skin pathologies, including basal cell carcinomas, melanoma, dermal nevi, combined nevi, junctional nevi, blue nevi, seborrheic keratosis, and hemangiomas. They are presented as 3D spectral attenuation maps exhibiting specific individual features for each group of pathologies. Along with intensity attenuation maps, 3D maps for content variations of three main skin chromophores (melanin, oxyhemoglobin, and deoxyhemoglobin), calculated in frame of a model based on modified Beer-Lambert law, are also presented. Advantages and disadvantages of the proposed data representation method are discussed.
CONCLUSIONS
The described 3D-representation method of triple spectral line imaging data shows promising potential for objective quantitative noncontact diagnosis of skin pathologies.
Topics: Diagnostic Imaging; Humans; Melanins; Nevus; Oxyhemoglobins; Skin
PubMed: 36114603
DOI: 10.1117/1.JBO.27.9.095005 -
PloS One 2021Pain in the elbow, shoulder, knee, lower back, and various other joints is relieved by adhesion of pyramidal thorn patches. To elucidate the pain relief mechanism...
Pain in the elbow, shoulder, knee, lower back, and various other joints is relieved by adhesion of pyramidal thorn patches. To elucidate the pain relief mechanism induced by the patches, we established a quantitative method for estimating the pain reduction and investigated the brain regions that change in association with pain relief. We first attempted to quantify the pain relief using transcutaneous electric stimulation (TCES) and a visual analog scale (VAS), and then applied near-infrared spectroscopy (NIRS) to the prefrontal cortex, including the dorsolateral prefrontal cortex (DLPFC) and the orbitofrontal cortex (OFC). We also examined the salivary oxytocin levels, which are thought to reflect oxytocin secretion levels from the posterior pituitary in the brain. Application of pyramidal thorn patches to pain regions decreased the pain degree estimated using TCES and VAS. Oxyhemoglobin levels were likely to be decreased in the left DLPFC on the basis of NIRS measurements during patch treatment, suggesting that the left DLPFC is involved in pain relief. On the other hand, the salivary oxytocin levels varied widely. A potential reason for the varying salivary oxytocin levels is its utilization in the pain region as an analgesic agent. Our results suggest that the left DLPFC will become a target brain region for pain therapy.
Topics: Adult; Dorsolateral Prefrontal Cortex; Humans; Oxyhemoglobins; Pain Management
PubMed: 34424921
DOI: 10.1371/journal.pone.0256626