New insights into ocular blood flow at very high altitudes

Little is known about the ocular and cerebral blood flow during exposure to increasingly hypoxic conditions at high altitudes. There is evidence that an increase in cerebral blood flow resulting from altered autoregulation constitutes a risk factor for acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) by leading to capillary overperfusion and vasogenic cerebral edema. The retina represents the only part of the central nervous system where capillary blood flow is visible and can be measured by noninvasive means. In this study we aimed to gain insights into retinal and choroidal autoregulatory properties during hypoxia and to correlate circulatory changes to symptoms of AMS and clinical signs of HACE. This observational study was performed within the scope of a high-altitude medical research expedition to Mount Muztagh Ata (7,546 m). Twenty seven participants underwent general and ophthalmic examinations up to a maximal height of 6,800 m. Examinations included fundus photography and measurements of retinal and choroidal blood flow, as well as measurement of arterial oxygen saturation and hematocrit. The initial increase in retinal blood velocity was followed by a decrease despite further ascent, whereas choroidal flow increase occurred later, at even higher altitudes. The sum of all adaptational mechanisms resulted in a stable oxygen delivery to the retina and the choroid. Parameters reflecting the retinal circulation and optic disc swelling correlated well with the occurrence of AMS-related symptoms. We demonstrate that sojourns at high altitudes trigger distinct behavior of retinal and choroidal blood flow. Increase in retinal but not in choroidal blood flow correlated with the occurrence of AMS-related symptoms.

Elevated body core temperature in medico-legal investigation of violent death

Pathologically elevated body core temperature, measured at the death scene, is an important finding in medico-legal investigation of violent deaths. An abnormally high rectal temperature at any death scene may point to an underlying pathology, the influence of certain drugs or a hidden cerebral traumatism, and death by suffocation which would remain undetected without further medico-legal investigations. Furthermore, hyperthermia and fever, if unrecognized, may result in an erroneous forensic estimation of time since death in the early postmortem period by the "Henssge method." By a retrospective study of 744 cases, the authors demonstrate that hyperthermia is a finding with an incidence of 10% of all cases of violent death. The main causes are: influence of drugs, malignant tumors, cerebral hypoxia as a result of suffocation, infections, and systemic inflammatory disorders. As a consequence it must be stated, that hyperthermia must be excluded in every medico-legal death scene investigation by a correct measurement of body core temperature and a comparison between the cooling rate of the body and the behavior of early postmortem changes, notably livor and rigor mortis.

Anesthetic and Airways Management of a Dog with Severe Tracheal Collapse during Intraluminal Stent Placement

This case report describes the anesthetic and airways management of a dog affected by 4th degree tracheal collapse and undergoing endoscope-guided intraluminal stent placement. After premedication with acepromazine and butorphanol, general anesthesia was induced with propofol and maintained with intravenous propofol and butorphanol in constant rate infusion. During intraluminal stent placement, oxygen was supplemented by means of a simple and inexpensive handmade device, namely, a ureteral catheter inserted into the trachea and connected to an oxygen source, which allowed for the maintenance of airways’ patency and adequate patient’s oxygenation, without decreasing visibility in the surgical field or interfering with the procedure. The use of the technique described in the present paper was the main determinant of the successful anesthetic management and may be proposed for similar critical cases in which surgical manipulation of the tracheal lumen, which may potentially result in hypoxia by compromising airways patency, is required.

High altitude journeys and flights are associated with an increased risk of flares in inflammatory bowel disease patients

BACKGROUND AND AIMS Hypoxia can induce inflammation in the gastrointestinal tract. However, the impact of hypoxia on the course of inflammatory bowel disease (IBD) is poorly understood. We aimed to evaluate whether flights and/or journeys to regions lying at an altitude of >2000m above the sea level are associated with flare-ups within 4weeks of the trip. METHODS IBD patients with at least one flare-up during a 12-month observation period were compared to a group of patients in remission. Both groups completed a questionnaire. RESULTS A total of 103 IBD patients were included (43 with Crohn's disease (CD): mean age 39.3±14.6years; 60 with ulcerative colitis (UC): mean age 40.4±15.1years). Fifty-two patients with flare-ups were matched to 51 patients in remission. IBD patients experiencing flare-ups had more frequently undertaken flights and/or journeys to regions >2000m above sea level within four weeks of the flare-up when compared to patients in remission (21/52 [40.4%] vs. 8/51 [15.7%], p=0.005). CONCLUSIONS Journeys to high altitude regions and/or flights are a risk factor for IBD flare-ups occurring within 4weeks of travel.

Targeting autophagy as a potential therapeutic approach for melanoma therapy

Melanoma, occurring as a rapidly progressive skin cancer, is resistant to current chemo- and radiotherapy, especially after metastases to distant organs has taken place. Most chemotherapeutic drugs exert their cytotoxic effect by inducing apoptosis, which, however, is often deficient in cancer cells. Thus, it is appropriate to attempt the targeting of alternative pathways, which regulate cellular viability. Recent studies of autophagy, a well-conserved cellular catabolic process, promise to improve the therapeutic outcome in melanoma patients. Although a dual role for autophagy in cancer therapy has been reported, both protecting against and promoting cell death, the potential for using autophagy in cancer therapy seems to be promising. Here, we review the recent literature on the role of autophagy in melanoma with respect to the expression of autophagic markers, the involvement of autophagy in chemo- and immunotherapy, as well as the role of autophagy in hypoxia and altered metabolic pathways employed for melanoma therapy.

Thermoreversible hyaluronan-based hydrogel supports in vitro and ex vivo disc-like differentiation of human mesenchymal stem cells

BACKGROUND CONTEXT The fate of human mesenchymal stem cells (hMSCs) supplied to the degenerating intervertebral disc (IVD) is still not fully understood and can be negatively affected by low oxygen, pH, and glucose concentration of the IVD environment. The hMSC survival and yield upon injection of compromised IVD could be improved by the use of an appropriate carrier and/or by predifferentiation of hMSCs before injection. PURPOSE To optimize hMSC culture conditions in thermoreversible hyaluronan-based hydrogel, hyaluronan-poly(N-isopropylacrylamide) (HA-pNIPAM), to achieve differentiation toward the disc phenotype in vitro, and evaluate whether preconditioning contributes to a better hMSC response ex vivo. STUDY DESIGN In vitro and ex vivo whole-organ culture of hMSCs. METHODS In vitro cultures of hMSCs were conducted in HA-pNIPAM and alginate for 1 week under hypoxia in chondropermissive medium alone and with the supplementation of transforming growth factor β1 or growth and differentiation factor 5 (GDF-5). Ex vivo, hMSCs were either suspended in HA-pNIPAM and directly supplied to the IVDs or predifferentiated with GDF-5 for 1 week in HA-pNIPAM and then supplied to the IVDs. Cell viability was evaluated by Live-Dead assay, and DNA, glycosaminoglycan (GAG), and gene expression profiles were used to assess hMSC differentiation toward the disc phenotype. RESULTS The HA-pNIPAM induced hMSC differentiation toward the disc phenotype more effectively than alginate: in vitro, higher GAG/DNA ratio and higher collagen type II, SOX9, cytokeratin-19, cluster of differentiation 24, and forkhead box protein F1 expressions were found for hMSCs cultured in HA-pNIPAM compared with those cultured in alginate, regardless of the addition of growth factors. Ex vivo, direct combination of HA-pNIPAM with the disc environment induced a stronger disc-like differentiation of hMSCs than predifferentiation of hMSCs followed by their delivery to the discs. CONCLUSIONS Hyaluronan-based thermoreversible hydrogel supports hMSC differentiation toward the disc phenotype without the need for growth factor supplementation in vitro and ex vivo. Further in vivo studies are required to confirm the suitability of this hydrogel as an effective stem cell carrier for the treatment of IVD degeneration.

Oxidative-nitrosative stress and systemic vascular function in highlanders with and without exaggerated hypoxemia

BACKGROUND Acute exposure to high altitude stimulates free radical formation in lowlanders, yet whether this persists during chronic exposure in healthy, well-adapted and maladapted highlanders suffering from chronic mountain sickness (CMS) remains to be established. METHODS Oxidative-nitrosative stress (as determined by the presence of the biomarkers ascorbate radical [A •- ], via electron paramagnetic resonance spectroscopy, and nitrite [NO 2 2 ], via ozone-based chemiluminescence) was assessed in venous blood of 25 male highlanders in Bolivia living at 3,600 m with CMS (n 5 13, CMS 1 ) and without CMS (n 5 12, CMS 2 ). Twelve age- and activity-matched, healthy, male lowlanders were examined at sea level and during acute hypoxia. We also measured fl ow-mediated dilatation (FMD), arterial stiffness defined by augmentation index normalized for a heart rate of 75 beats/min (AIx-75), and carotid intima-media thickness (IMT). RESULTS Compared with normoxic lowlanders, oxidative-nitrosative stress was moderately increased in the CMS 2 group ( P , .05), as indicated by elevated A •- (3,191 457 arbitrary units [AU] vs 2,640 445 AU) and lower NO 2 2 (206 55 nM vs 420 128 nM), whereas vascular function remained preserved. This was comparable to that observed during acute hypoxia in lowlanders in whom vascular dysfunction is typically observed. In contrast, this response was markedly exaggerated in CMS 1 group (A •- , 3,765 429 AU; NO 2 2 , 148 50 nM) compared with both the CMS 2 group and lowlanders ( P , .05). This was associated with systemic vascular dysfunction as indicated by lower ( P , .05 vs CMS 2 ) FMD (4.2% 0.7% vs 7.6% 1.7%) and increased AIx-75 (23% 8% vs 12% 7%) and carotid IMT (714 127 m M vs 588 94 m M). CONCLUSIONS Healthy highlanders display a moderate, sustained elevation in oxidative-nitrosative stress that, unlike the equivalent increase evoked by acute hypoxia in healthy lowlanders, failed to affect vascular function. Its more marked elevation in patients with CMS may contribute to systemic vascular dysfunction.

Fetal programming of pulmonary vascular dysfunction in mice: role of epigenetic mechanisms.

Insults during the fetal period predispose the offspring to systemic cardiovascular disease, but little is known about the pulmonary circulation and the underlying mechanisms. Maternal undernutrition during pregnancy may represent a model to investigate underlying mechanisms, because it is associated with systemic vascular dysfunction in the offspring in animals and humans. In rats, restrictive diet during pregnancy (RDP) increases oxidative stress in the placenta. Oxygen species are known to induce epigenetic alterations and may cross the placental barrier. We hypothesized that RDP in mice induces pulmonary vascular dysfunction in the offspring that is related to an epigenetic mechanism. To test this hypothesis, we assessed pulmonary vascular function and lung DNA methylation in offspring of RDP and in control mice at the end of a 2-wk exposure to hypoxia. We found that endothelium-dependent pulmonary artery vasodilation in vitro was impaired and hypoxia-induced pulmonary hypertension and right ventricular hypertrophy in vivo were exaggerated in offspring of RDP. This pulmonary vascular dysfunction was associated with altered lung DNA methylation. Administration of the histone deacetylase inhibitors butyrate and trichostatin A to offspring of RDP normalized pulmonary DNA methylation and vascular function. Finally, administration of the nitroxide Tempol to the mother during RDP prevented vascular dysfunction and dysmethylation in the offspring. These findings demonstrate that in mice undernutrition during gestation induces pulmonary vascular dysfunction in the offspring by an epigenetic mechanism. A similar mechanism may be involved in the fetal programming of vascular dysfunction in humans.

Clinical Proton MR Spectroscopy in Central Nervous System Disorders.

A large body of published work shows that proton (hydrogen 1 [(1)H]) magnetic resonance (MR) spectroscopy has evolved from a research tool into a clinical neuroimaging modality. Herein, the authors present a summary of brain disorders in which MR spectroscopy has an impact on patient management, together with a critical consideration of common data acquisition and processing procedures. The article documents the impact of (1)H MR spectroscopy in the clinical evaluation of disorders of the central nervous system. The clinical usefulness of (1)H MR spectroscopy has been established for brain neoplasms, neonatal and pediatric disorders (hypoxia-ischemia, inherited metabolic diseases, and traumatic brain injury), demyelinating disorders, and infectious brain lesions. The growing list of disorders for which (1)H MR spectroscopy may contribute to patient management extends to neurodegenerative diseases, epilepsy, and stroke. To facilitate expanded clinical acceptance and standardization of MR spectroscopy methodology, guidelines are provided for data acquisition and analysis, quality assessment, and interpretation. Finally, the authors offer recommendations to expedite the use of robust MR spectroscopy methodology in the clinical setting, including incorporation of technical advances on clinical units. © RSNA, 2014 Online supplemental material is available for this article.

Oxygen regulates molecular mechanisms of cancer progression and metastasis

Oxygen is the basic molecule which supports life and it truly is “god's gift to life.” Despite its immense importance, research on “oxygen biology” has never received the light of the day and has been limited to physiological and biochemical studies. It seems that in modern day biology, oxygen research is summarized in one word “hypoxia.” Scientists have focused on hypoxia-induced transcriptomics and molecular–cellular alterations exclusively in disease models. Interestingly, the potential of oxygen to control the basic principles of biology like homeostatic maintenance, transcription, replication, and protein folding among many others, at the molecular level, has been completely ignored. Here, we present a perspective on the crucial role played by oxygen in regulation of basic biological phenomena. Our conclusion highlights the importance of establishing novel research areas like oxygen biology, as there is great potential in this field for basic science discoveries and clinical benefits to the society.

Monitoring cerebral oxygenation during balloon occlusion with multichannel NIRS

We report on oxygenation changes noninvasively recorded by multichannel continuous-wave near infrared spectroscopy (CW-NIRS) during endovascular neuroradiologic interventions requiring temporary balloon occlusion of arteries supplying the cerebral circulation. Digital subtraction angiography (DSA) provides reference data on the site, timing, and effectiveness of the flow stagnation as well as on the amount and direction of collateral circulation. This setting allows us to relate CW-NIRS findings to brain specific perfusion changes. We focused our analysis on the transition from normal perfusion to vessel occlusion, i.e., before hypoxia becomes clinically apparent. The localization of the maximal response correlated either with the core (occlusion of the middle cerebral artery) or with the watershed areas (occlusion of the internal carotid artery) of the respective vascular territories. In one patient with clinically and angiographically confirmed insufficient collateral flow during carotid artery occlusion, the total hemoglobin concentration became significantly asymmetric, with decreased values in the ipsilateral watershed area and contralaterally increased values. Multichannel CW-NIRS monitoring might serve as an objective and early predictive marker of critical perfusion changes during interventions-to prevent hypoxic damage of the brain. It also might provide valuable human reference data on oxygenation changes as they typically occur during acute stroke.

Molecular characterisation and expression of Atlantic cod (Gadus morhua) myoglobin from two populations held at two different acclimation temperatures.

Much previous research has demonstrated the plasticity of myoglobin concentrations in both cardiac and skeletal myocytes in response to hypoxia and training. No study has yet looked at the effect of thermal acclimation on myoglobin in fish. Atlantic cod (Gadus morhua) from two different populations, i.e. the North Sea and the North East Arctic, were acclimated to 10 and 4 degrees C. Both the myoglobin mRNA and myoglobin protein in cod hearts increased significantly by up to 3.7 and 2.3 fold respectively as a result of acclimation to 4 degrees C. These increments were largest in the Arctic population, which in earlier studies have been shown to possess cold compensated metabolic demands at low temperatures. These metabolic demands associated with higher mitochondrial capacities may have driven the increase in cardiac myoglobin concentrations, in order to support diffusive oxygen supply. At the same time the increase in myoglobin levels may serve further functions during cold acclimation, for example, protection of the cell against reactive oxygen species, and scavenging nitric oxide, thereby contributing to the regulation of mitochondrial volume density.

Computer simulation of glioma growth and morphology.

Despite major advances in the study of glioma, the quantitative links between intra-tumor molecular/cellular properties, clinically observable properties such as morphology, and critical tumor behaviors such as growth and invasiveness remain unclear, hampering more effective coupling of tumor physical characteristics with implications for prognosis and therapy. Although molecular biology, histopathology, and radiological imaging are employed in this endeavor, studies are severely challenged by the multitude of different physical scales involved in tumor growth, i.e., from molecular nanoscale to cell microscale and finally to tissue centimeter scale. Consequently, it is often difficult to determine the underlying dynamics across dimensions. New techniques are needed to tackle these issues. Here, we address this multi-scalar problem by employing a novel predictive three-dimensional mathematical and computational model based on first-principle equations (conservation laws of physics) that describe mathematically the diffusion of cell substrates and other processes determining tumor mass growth and invasion. The model uses conserved variables to represent known determinants of glioma behavior, e.g., cell density and oxygen concentration, as well as biological functional relationships and parameters linking phenomena at different scales whose specific forms and values are hypothesized and calculated based on in vitro and in vivo experiments and from histopathology of tissue specimens from human gliomas. This model enables correlation of glioma morphology to tumor growth by quantifying interdependence of tumor mass on the microenvironment (e.g., hypoxia, tissue disruption) and on the cellular phenotypes (e.g., mitosis and apoptosis rates, cell adhesion strength). Once functional relationships between variables and associated parameter values have been informed, e.g., from histopathology or intra-operative analysis, this model can be used for disease diagnosis/prognosis, hypothesis testing, and to guide surgery and therapy. In particular, this tool identifies and quantifies the effects of vascularization and other cell-scale glioma morphological characteristics as predictors of tumor-scale growth and invasion.

THE EXPRESSION AND CELLULAR LOCALIZATION OF CC-CHEMOKINE RECEPTOR 5 (CCR5) AFTER TRAUMATIC BRAIN INJURY

Traumatic brain injury results from a primary insult and secondary events that together result in tissue injury. This primary injury occurs at the moment of impact and damage can include scalp laceration, skull fraction, cerebral contusions and lacerations as well as intracranial hemorrhage. Following the initial insult, a delayed response occurs and is characterized by hypoxia, ischemia, cerebral edema, and infection. During secondary brain injury, a series of neuroinflammatory events are triggered that can produce additional damage but may also help to protect nervous tissue from invading pathogens and help to repair the damaged tissue. Brain microglia and astrocytes become activated and migrate to the site of injury where these cells secrete immune mediators such as cytokines and chemokines. CC-chemokine receptor 5 (CCR5) is a member of the CC chemokine receptor family of seven transmembrane G protein coupled receptors. CCR5 is expressed in the immune system and is found in monocytes, leukoctyes, memory T cells, and immature dendritic cells. Upon binding to its ligands, CCR5 functions in the chemotaxis of these immune cells to the site of inflammation. In the CNS, CCR5 and its ligands are expressed in multiple cell types. In this study, I investigated whether CCR5 expression is altered in brain after traumatic brain injury. I examined the time course of CCR5 protein expression in cortex and hippocampus using quantitative western analysis of tissues from injured rat brain after mild impact injury. In addition, I also investigated the cellular localization of CCR5 before and after brain injury using confocal microscopy. I have observed that after brain injury CCR5 is upregulated in a time dependent manner in neurons of the parietal cortex and hippocampus. The absence of CCR5 expression in microglia and its delayed expression in neurons after injury suggests a role for CCR5 in neuronal survival after injury.

THE EXPRESSION AND CELLULAR LOCALIZATION OF CC-CHEMOKINE RECEPTOR 5 (CCR5) AFTER TRAUMATIC BRAIN INJURY

Traumatic brain injury results from a primary insult and secondary events that together result in tissue injury. This primary injury occurs at the moment of impact and damage can include scalp laceration, skull fraction, cerebral contusions and lacerations as well as intracranial hemorrhage. Following the initial insult, a delayed response occurs and is characterized by hypoxia, ischemia, cerebral edema, and infection. During secondary brain injury, a series of neuroinflammatory events are triggered that can produce additional damage but may also help to protect nervous tissue from invading pathogens and help to repair the damaged tissue. Brain microglia and astrocytes become activated and migrate to the site of injury where these cells secrete immune mediators such as cytokines and chemokines. CC-chemokine receptor 5 (CCR5) is a member of the CC chemokine receptor family of seven transmembrane G protein coupled receptors. CCR5 is expressed in the immune system and is found in monocytes, leukoctyes, memory T cells, and immature dendritic cells. Upon binding to its ligands, CCR5 functions in the chemotaxis of these immune cells to the site of inflammation. In the CNS, CCR5 and its ligands are expressed in multiple cell types. In this study, I investigated whether CCR5 expression is altered in brain after traumatic brain injury. I examined the time course of CCR5 protein expression in cortex and hippocampus using quantitative western analysis of tissues from injured rat brain after mild impact injury. In addition, I also investigated the cellular localization of CCR5 before and after brain injury using confocal microscopy. I have observed that after brain injury CCR5 is upregulated in a time dependent manner in neurons of the parietal cortex and hippocampus. The absence of CCR5 expression in microglia and its delayed expression in neurons after injury suggests a role for CCR5 in neuronal survival after injury.