Effects of spinal immobilization at a 20° angle on cerebral oxygen saturations measured by INVOS™

Background and aim of the study

In this study, we aimed to investigate whether performing the immobilization at 20° instead of 0° changes cerebral oxygenation.

Fetal lamb coagulation system during birth asphyxia

Levels of many coagulation factors are low in the healthy infant and even lower in the asphyxiated premature infant. We investigated whether a brief exposure to asphyxia at the time of birth causes the activation and consumption of coagulation factors. Following delivery by caesarean section, premature lambs were asphyxiated by occluding the endotracheal tube for 10 min and then resuscitated. Blood was obtained prior to and following birth for measurement of blood gases and the coagulation system. Birth asphyxia in the premature lamb resulted in thrombin generation and rapid consumption of specific coagulation factors.     

Studies on the regulation of myocardial blood flow in man II. Effects of acute arterial hypoxia

To determine whether adjustment of myocardial blood flow (MBF), myocardial oxygen consumption (MVO₂) and myocardial substrate uptake (MSU) to acute arterial hypoxia is influenced by training effects on the heart, 7 trained and 7 untrained healthy individuals were investigated. MBF (argon method), MVO₂ and MSU of glucose, lactate and free fatty acids were measured at rest during normoxia and two different stages of acute arterial hypoxia: a) 12.82 vol% O₂; b) 8.74 vol% O₂. Measurements were carried out during hemodynamic and respiratory steady state conditions. Myocardial flow and metabolism of athletes were significantly (p<0.01) lower compared to untrained subjects. In the trained cohort, MBF increased from 65 ± 19 to 73 ± 16 (a) and 98 ± 23 (b) ml/min·100 g. MVO₂ remained at normoxic control level of 8.00 ± 2.27 ml/min·100g. In the untrained group, MBF increased from 77 ± 15 to 84 ± 20 (a) and 108 ± 18 (b) ml/min · 100g. Again, there was no significant deviation in MVO₂ from the normoxic level of 10.11 ± 1.90 ml/min·100g. Decrease in arterial oxygen content was overcompensated by an increase in coronary conductance resulting in a significantly improved efficiency of myocardial perfusion during severe hypoxia. MSU of glucose, lactate and free fatty acids as well as calculated ATP production did not change significantly during hypoxia. It is concluded that training effects on the heart do not influence regulation of MBF, MVO₂ and MSU during moderate or severe acute arterial hypoxia. Reaction of coronary smooth muscle tone to a decrease in oxygen partial pressure is independent from training effects. However, both acute arterial hypoxia and physical training exert synergetic effects on the heart by reducing myocardial oxygen consumption per heart beat. Thus, it is assumed that adaptive properties of myocardial blood flow and metaboüsm to severe hypoxia are more pronounced in trained than in untrained individuals.     

Phospholipid membrane-decorated deep-penetrated nanocatalase relieve tumor hypoxia to enhance chemo-photodynamic therapy

Hypoxia is a serious impediment to current treatments of many malignant tumors. Catalase, an antioxidant enzyme, is capable of decomposing endogenous hydrogen peroxide (H₂O₂) into oxygen for tumor reoxygenation, but suffered from in vivo instability and limited delivery to deep interior hypoxic regions in tumor. Herein, a deep-penetrated nanocatalase-loading DiIC₁₈ (5, DiD) and soravtansine (Cat@PDS) were provided by coating catalase nanoparticles with PEGylated phospholipids membrane, stimulating the structure and function of erythrocytes to relieve tumor hypoxia for enhanced chemo-photodynamic therapy. After intravenous administration, Cat@PDS preferentially accumulated at tumor sites, flexibly penetrated into the interior regions of tumor mass and remarkably relieved the hypoxic status in tumor. Notably, the Cat@PDS + laser treatment produced striking inhibition of tumor growth and resulted in a 97.2% suppression of lung metastasis. Thus, the phospholipids membrane-coated nanocatalase system represents an encouraging nanoplatform to relieve tumor hypoxia and synergize the chemo-photodynamic cancer therapy.     

Interferon-α as angiogenesis inhibitor: Learning from tumor models

Interferon-α (IFN-α), a cytokine with marked therapeutic activity in transplantable tumor models, has been identified as powerful angiogenesis inhibitor. The effects of IFN-α on the vasculature have been mainly attributed to inhibition of basic fibroblast growth factor production by tumor cells or downregulation of IL-8 and vascular endothelial growth factor gene expression. Moreover, IFN-α has direct effects on endothelial cells (EC), including impairment of their proliferation and migration. The gene expression profile induced by IFN-α in EC has recently been defined, and it was found that several genes encoding negative regulators of angiogenesis are upmodulated, thus providing a potential amplification mechanism for this biological activity. The anti-angiogenic effects of IFN-α appear to be associated with increased hypoxia and ischemic necrosis in subcutaneous xenograft models, whereas in transgenic mouse models, IFN-α may simultaneously interfere with both blood vessels and tumor cell proliferation, leading to regression of tumors without necrosis. The consequences of IFN-α therapy on the invasive and metastatic behavior of tumor cells are currently unknown. Finally, as effective anti-angiogenic therapy with IFN-α demands sustained localized production of this cytokine, innovative strategies of targeted delivery of the IFN-α gene into tumors are discussed.     

Use of face mask by blood donors during the COVID-19 pandemic: Impact on donor hemoglobin concentration: A bane or a boon

BackgroundCOVID-19 virus has caused the world’s deadliest pandemic. Early April 2020, the Delhi Government made it compulsory for people to wear face masks while going outdoors to curb disease spread. Prolonged use of surgical masks during the pandemic has been reported to cause many adverse effects. Intermittent hypoxia has been shown to activate erythropoietin (EPO leading to increased hemoglobin mass.AimTo analyze whether face mask induced intermittent hypoxia has any effect on the hemoglobin levels of healthy blood donors.Materials and methodsWe retrospectively analyzed donor data from 1st July 2019-31st December 2020 for hemoglobin distribution across hemoglobin ranges and donor deferral on basis of hemoglobin. Study population was divided into two cohorts Group 1- (1st July 2019-31 st March 2020): before implementation of mandatory face masks Group 2- (1st April 2020-31 st December 2020): after implementation of mandatory face masksResultsMean Hb of blood donors in Group 2 (15.01 ± 1.1 g/dl) was higher than Group1 (14.49 ± 1.15 g/dl), (p < 0.0001). 47.1 % group2 donors had Hb of 16.1−18 g/dl compared to group1 (38.4 %). 52.9 % group 2 donors had Hb between 12.5−15 g/dl compared to 61.6 % Group 1 (p < 0.05). Deferral due to anemia was lesser in group 2 compared to group 1 (p < 0.00001). Group 2 had significantly higher deferral due to high Hb (>18 gm/dl) was than Group 1 (p = 0.0039).ConclusionThis study including 19504 blood donors spanning over one and a half year shows that prolonged use of face mask by blood donors may lead to intermittent hypoxia and consequent increase in hemoglobin mass.     

Cardiac output during exercise: A comparison of four methods

Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from the right atrium (Q_Fick‐M), Innocor (inert gas rebreathing; Q_Inn), Physioflow (impedance cardiography; Q_Phys), and Nexfin (pulse contour analysis; Q_Pulse) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (F_iO₂ = 12%). While all four methods reported a progressive increase in Q with exercise intensity, the slopes of the Q/oxygen uptake (VO₂) relationship differed by up to 50% between methods in both normoxia [4.9 ± 0.3, 3.9 ± 0.2, 6.0 ± 0.4, 4.8 ± 0.2 L/min per L/min (mean ± SE) for Q_Fick‐M, Q_Inn, Q_Phys and Q_Pulse, respectively; P = 0.001] and hypoxia (7.2 ± 0.7, 4.9 ± 0.5, 6.4 ± 0.8 and 5.1 ± 0.4 L/min per L/min; P = 0.04). In hypoxia, the increase in the Q/VO₂ slope was not detected by Nexfin. In normoxia, Q increases by 5–6 L/min per L/min increase in VO₂, which is within the 95% confidence interval of the Q/VO₂ slopes determined by the modified Fick method, Physioflow, and Nexfin apparatus while Innocor provided a lower value, potentially reflecting recirculation of the test gas into the pulmonary circulation. Thus, determination of Q during exercise depends significantly on the applied method.