Adv Exp Med Biol
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This study investigates the relationship between changes in brain tissue haemodynamics, oxygenation and oxidised cytochrome-c-oxidase ([oxCCO]) in the adult brain during hyperoxia and hypercapnea. 10 healthy volunteers were studied. We measured the mean blood flow velocity of the right middle cerebral artery (Vmca) with transcranial Doppler (TCD) and changes in concentrations of total haemoglobin ([HbT]=[HbO2]+[HHb]), haemoglobin difference ([Hbdiff]=[HbO2]-[HHb]) and [oxCCO] with broadband near-infrared spectroscopy (NIRS). We also measured the absolute tissue oxygenation index (TOI) using NIR spatially resolved spectroscopy. ⋯ During hypercapnea there was an increase in TOI (2.76 +/- 2.16%), [Hbdiff] (7.36 +/- 2.64), [HbT] (2.61 +/- 2.7 microM), Vmca (14.92 +/- 17.5%) and in the oxidation of [oxCCO] (0.25 +/- 0.17 microM). Correlation analysis shows that there was association between [oxCCO] and TOI, [Hbdiff] and [HbT] (r=0.83, r=0.93 and r=0.82) but not with Vmca (r=0.33). We conclude that an increase in [oxCCO] was seen during both challenges and it was highly associated with brain tissue oxygenation.
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Forkhead Transcription Factors: Vital Elements in Biology and Medicine provides a unique platform for the presentation of novel work and new insights into the vital role that forkhead transcription factors play in both cellular physiology as well as clinical medicine. Internationally recognized investigators provide their insights and perspectives for a number of forkhead genes and proteins that may have the greatest impact for the development of new strategies for a broad array of disorders that can involve aging, cancer, cardiac function, neurovascular integrity, fertility, stem cell differentiation, cellular metabolism, and immune system regulation. Yet, the work clearly sets a precedent for the necessity to understand the cellular and molecular function of forkhead proteins since this family of transcription factors can limit as well as foster disease progression depending upon the cellular environment. ⋯ Furthermore, FoxO transcription factors are exciting considerations for disorders such as cancer in light of their pro-apoptotic and inhibitory cell cycle effects as well as diabetes mellitus given the close association FoxOs hold with cellular metabolism. In addition, these transcription factors are closely integrated with several novel signal transduction pathways, such as erythropoietin and Wnt proteins, that may influence the ability of FoxOs to lead to cell survival or cell injury. Further understanding of both the function and intricate nature of the forkhead transcription factor family, and in particular the FoxO proteins, should allow selective regulation of cellular development or cellular demise for the generation of successful future clinical strategies and patient well-being.
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Sensory information in the lung is generated by airway receptors located throughout the respiratory tract. This information is mainly carried by the vagus nerves and yields multiple reflex responses in disease states (cough, bronchoconstriction and mucus secretion). ⋯ A single sensory unit contains homogeneous or heterogeneous types of receptors, providing varied and mixed behavior. Thus, the sensory units are not only transducers, but also processors that integrate information in different modes.
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Some preterm infants have poor cerebral autoregulation. The concordance between cerebral intravascular oxygenation (HbD), computed as the difference between oxygenated (HbO2) and deoxygenated (Hb) haemoglobin, and mean arterial blood pressure (MABP) reflects impaired autoregulation. As HbD is not an absolute value, we developed mathematics to prove that the cerebral tissue oxygenation (TOI), an absolute signal computed as the ratio of HbO2 to total haemoglobin (Hb+HbO2), may replace HbD. ⋯ HbD and TOI were obtained with the NIRO-300 (Hamamatsu, Japan). Invasive MABP was measured continuously. All mathematics showed a strong similarity between HbD and TOI.
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For adequate development and functioning of the neonatal brain, sufficient oxygen (O2) should be available. With a fast sampling (f(s) > 50 Hz) continuous wave NIRS device, arterial (SaO2) and venous (SvO2) saturation can be measured using the physiological fluctuations in the oxyhemoglobin (O2Hb) and total hemoglobin (tHb) concentrations due to heart action and respiration. Before using this technique in a neonatal setting, the method was verified on adult volunteers (n=7) by decreasing inspired oxygen down to an arterial saturation of 70% using a pulse oximeter as reference. ⋯ A good agreement between calculated SaO2 and reference SaO2 from pulse oximetry was found (bias range -3.5% to 5.2%, SD of the residuals 1.3% to 3.5%). Optode spacing of 15 mm yielded a negative bias compared to optode spacing of 45 mm. It was not always possible to calculate SvO2 because the respiration peak could not always be detected.