This hypothesis proposes that increased extracellular glutamate in Amyotrophic Lateral Sclerosis (ALS) and cerebral ischemia, currently viewed as a trigger for excitotoxicity, is actually beneficial as it stimulates the utilization of glutamate as metabolic fuel. Renewed appreciation of glutamate oxidation by ischemic neurons has raised questions regarding the role of extracellular glutamate in ischemia. Is it detrimental, as suggested by excitotoxicity in early in vitro studies, or beneficial, as suggested by its oxidation in later in vivo studies? The (...) answer may depend on the activity of N‐methyl‐D‐aspartate (NMDA) glutamate receptors. Early in vitro procedures co‐activated NMDA receptors (NMDARs) containing 2A (GluN2A) and 2B (GluN2B) subunits, an event now believed to trigger excitotoxicity; however, during in vivo ischemia D‐serine and zinc molecules are released and these ensure only GluN2B receptors are stimulated. This not only prevents excitotoxicity but also initiates signaling cascades that allow ischemic neurons to import and oxidize glutamate. (shrink)

The present work is aimed at investigating the effects of myocardial infarction and ischemia on induction of ventricular fibrillation. Electrophysiologic effects of global and local ischemia (variation of the dispersion of refractory periods as well as conduction velocity) on initiation of reentry mechanisms was studied by means of computer simulations based on a cellular automata model of propagation of activation wave through a ventricular surface element. A local area of ischemia where effects of the dispersion of refractory (...) periods are investigated is then simulated. This is made using a Gaussian distribution characterized by its mean and standard deviation. These simulations show that ischemia is capable of initiating reentry phenomena which propagate through the whole ventricle; they are responsible for ventricular fibrillation which causes sudden cardiac death, even when ischemia only involves limited parts of the myocardium. Statistical study of the probability of reentries as a function of both of the size of ischemic zones and the rate of dispersion of refractory periods shows that the latter parameter is of primary importance in triggering cardiac reentries. (shrink)

Different housing conditions, including housing space and the physiological and social environment, may affect rodent behavior. Here, we examined the effects of different housing conditions on post-stroke angiogenesis and functional recovery to clarify the ambiguity about environmental enrichment and its components. Male rats in the model groups underwent right middle cerebral artery occlusion followed by reperfusion. The MCAO rats were divided into four groups: the physical enrichment group, the social enrichment group, the combined physical and social enrichment group and the (...) ischemia/reperfusion + standard conditioning group. The rats in the sham surgery group were housed under standard conditions. In a set of behavioral tests, including the modified Neurological Severity Score, rotarod test, and adhesive removal test, we demonstrated that the animals in the enriched condition groups exhibited significantly improved neurological functions compared to those in the standard housing group. Smaller infarction volumes were observed in the animals of the PSE group by MRI detection. The enriched conditions increased the microvessel density in the ischemic boundary zone, as revealed by CD31 immunofluorescent staining. The immunochemical and q-PCR results further showed that environmental enrichment increased the expression levels of angiogenic factors after ischemia/reperfusion injury. Our data suggest that all three enrichment conditions promoted enhanced angiogenesis and functional recovery after ischemia/reperfusion injury compared to the standard housing, while only exposure to the combination of both physical and social enrichment yielded optimal benefits. (shrink)

BackgroundA patient who fulfils the due diligence requirements for euthanasia, and is medically suitable, is able to donate his organs after euthanasia in Belgium, the Netherlands and Canada. Since 2012, more than 70 patients have undergone this combined procedure in the Netherlands. Even though all patients who undergo euthanasia are suffering hopelessly and unbearably, some of these patients are nevertheless willing to help others in need of an organ. Organ donation after euthanasia is a so-called donation after circulatory death (DCD), (...) Maastricht category III procedure, which takes place following cardiac arrest, comparable to donation after withdrawal of life sustaining therapy in critically ill patients. To minimize the period of organ ischemia, the patient is transported to the operating room immediately after the legally mandated no-touch period of 5 min following circulatory arrest. This means that the organ donation procedure following euthanasia must take place in the hospital, which appears to be insurmountable to many patients who are willing to donate, since they already spent a lot of time in the hospital. Case presentationThis article describes the procedure of organ donation after euthanasia starting at home (ODAEH) following anesthesia in a former health care professional suffering from multiple system atrophy. This case is unique for at least two reasons. He spent his last conscious hours surrounded by his family at home, after which he underwent general anaesthesia and was intubated, before being transported to the hospital for euthanasia and organ donation. In addition, the patient explicitly requested the euthanasia to be performed in the preparation room, next to the operating room, in order to limit the period of organ ischemia due to transport time from the intensive care unit to the operating room. The medical, legal and ethical considerations related to this illustrative case are subsequently discussed.ConclusionsOrgan donation after euthanasia is a pure act of altruism. This combined procedure can also be performed after the patient has been anesthetized at home and during transportation to the hospital. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Back to the Future:Obtaining Organs from Non-Heart-Beating CadaversRobert M. Arnold (bio) and Stuart J. Youngner (bio)Organ Transplantation requires viable donor organs. This simple fact has become the Achilles' heel of transplantation programs. Progress in immunology and transplant surgery has outstripped the supply of available organs. Between 1988 and 1991, for example, the number of transplant candidates on waiting lists increased by about 55 percent, while the number of donors (...) increased only about 16 percent.1 By the end of March 1993, more than 30,000 potential recipients awaited transplantation (United Network for Organ Sharing Database (UNOS) 1993). Every day six of these patients die prior to receiving a heart or liver transplant, while patients needing kidney transplants must tolerate a lower quality of life on dialysis (Grenvik 1992; Evans, Orians, and Ascher 1992).This scarcity is likely to get worse. As transplantation becomes more successful, it is being offered to sicker and older patients. Attempts to transplant other solid organs, such as small bowel and pancreas, will only fuel the demand for donors. However, the current source of organs is unlikely to grow. Most organs come from patients who have been declared dead by neurologic criteria (commonly referred to as "brain dead" or heart-beating cadaver donors (HBCDs) because their hearts are beating at the time of procurement). Estimates of the potential pool of HBCDs have been revised downward from 20,000-27,000 to roughly 10,000-12,000 (Nathan et al. 1991). Improvements in automobile safety and handgun legislation will likely lead to further reductions. Moreover, the rate of procurement from HBCDs has remained relatively flat despite extensive public awareness campaigns and legislation requiring hospitals to routinely request donation from families of dead patients (Caplan et al. 1992).If organ transplantation is going to continue to flourish, alternative [End Page 103] sources of organs must be found. Recently the University of Pittsburgh Medical Center (UPMC) proposed procuring organs from patients who have been declared dead by traditional cardiopulmonary rather than brain-oriented criteria after they or their families have decided to forgo life-sustaining treatment—hereafter referred to as the Pittsburgh protocol (UPMC Policy 1993). These patients are typically referred to as non-heart-beating cadaver donors (NHBCDs) because their hearts are no longer beating at the time of organ procurement.Although NHBCDs were a major source of transplantable kidneys prior to the institution of death by neurologic criteria, their usefulness was limited by "warm ischemia time." This term refers to the injury to tissues that occurs when the blood supply is interrupted and before the organs are cooled and reperfused. Under the Pittsburgh protocol, therapy is withdrawn in the operating room where a waiting surgical team removes organs immediately after death is declared. By controlling the place and time of death, it has been possible to minimize warm ischemia time and thus solve the technical problems previously associated with procurement from NHBCDs.The potential contribution of NHBCD organs is significant. Nathan (1992), using data from Delaware Valley Transplant Program, concludes that the use of severely brain injured, but not "brain dead" patients, would increase the donor pool by 20-25 percent. Moreover, unpublished data from the Pittsburgh organ procurement organization, the Center for Organ Recovery and Education (CORE), suggests that these organs, particularly kidneys, function as well as those procured from HBCDs (Broznick 1993).This volume is devoted to the ethical, psychosocial, and public policy implications of procuring organs from non-heart-beating cadaver donors after a discussion to forgo life-sustaining treatment. The genesis of this volume was a project in which we invited leading experts in transplantation, ethics, and public policy to use the Pittsburgh protocol as a starting point for exploring a broad range of issues associated with attempts to procure organs from NHBCDs. The issues raised by NHBCDs turned out to have important implications about the fundamental conceptual and moral assumptions underlying organ procurement.Although each of the papers in this volume can be read separately, we intend the volume to be read as a whole. Many of the latter pieces on the ethical implications of the policy are best understood in light of the earlier background papers... (shrink)

Previous research has documented that type 2 diabetes mellitus is associated with cognitive impairment. Psychological variables were repeatedly investigated to understand why T2DM patients are poorly active, despite standards of medical care recommends performing aerobic and resistance exercise regularly and reducing the amount of time spent sitting. This exploratory study aims to investigate how affective variables as thoughts, feelings, and individuals’ stage of exercise adoption can modulate low cognitive performances during an experimental procedure based on exercise. The Exercise Thoughts Questionnaire, (...) Exercise-Induced Feeling Scale, and Physical Activity Stage of Change were administered to a sample of 12 T2DM patients. The Bivalent Shape Task alone, BST with exercise [control exercise recovery + BST], and BST with metaboreflex [post-exercise muscle ischemia + BST] were used as mental task, and response time to congruent, incongruent, and neutral stimuli was recorded. Concomitant cerebral oxygenation was evaluated by near-infrared spectroscopy. As expected, T2DM patients performed significantly better when the stimulus was presented in congruent trials. In the CER + BST session, T2DM patients showed longer reaction time to incongruent trials than in the PEMI + BST and BST alone sessions. Positive feelings toward exercise seem to modulate cognitive performances in high challenging task only if T2DM patients were conscious to play exercise. These results could provide some insights for health intervention targeting exercise for patients with T2DM in order to enhance cognitive performances. (shrink)

Glutamate is the major excitatory neurotransmitter in the mammalian brain, with receptors on every neuron in the central nervous system; it has major roles in fast synaptic transmission and in the establishment of certain forms of memory. More than 20 years ago Olney and his colleagues(1) described the [Excitotoxic Hypothesis] which postulates that, in addition to its normal function in the healthy brain, glutamate can kill neurons by prolonged, receptorsmediated depolarization resulting in irreversible disturbances in ion homeostasis. Therefore, glutamate is (...) a two‐edged sword; in certain undefined, adverse conditions it undergoes a transition from neurotransmitter to neurotoxin. Its toxicity has been implicated in the death of neurons in ischemia, epilepsy, and the neurodegenerative disorders such as Alzheimer's, Huntington's, and Parkinson's diseases(2–5). Recent advances in the molecular cloning of the genes for the glutamate family of receptors has revealed a plethora of receptor subtypes and an unexpected level of complexity in the mechanisms of receptor expression and function. (shrink)

Facial fat grafting techniques often offer impressive surgical results. However, fatal complications, such as irreversible cerebral ischemia, blindness, and hemiplegia are associated with them. We have presented a case report of a patient who presented with a massive cerebral infarction, a serious complication of facial autologous fat injection. The patient was a 28-year-old female who experienced motor dysfunction of the left extremities, which was accompanied with loss of consciousness immediately following fat grafting for facial augmentation. Imaging studies suggested that (...) the patient had a large cerebral infarction on the right frontal, temporal, and parietal lobes due to complete occlusion of her right external carotid artery. Emergency decompressive craniectomy was completed in addition to multiple follow-up medical treatments. The patient recovered after 4 months with reduced motor function in her left upper extremity. This report further summarizes published cases of massive cerebral ischemia after facial injection of autologous fat, as well as lists high-risk facial areas and critical warnings. (shrink)

Carbon monoxide (CO), a product of organic oxidation processes, arises in vivo during cellular metabolism, most notably heme degradation. CO binds to the heme iron of most hemoproteins. Tissue hypoxia following hemoglobin saturation represents a principle cause of CO‐induced mortality in higher organisms, though cellular targets cannot be excluded. Despite extreme toxicity at high concentrations, low concentrations of CO can confer cytoprotection during ischemia/reperfusion or inflammation‐induced tissue injury. Likewise, heme oxygenase, an enzyme that produces CO, biliverdin and iron, as (...) well as a secondary increase in ferritin synthesis, from the oxidation of heme, can confer protection in vivo and in vitro. CO has been shown to affect several intracellular signaling pathways, including guanylate cyclase, which generates guanosine 3′:5′ cyclic monophosphate and the mitogen‐activated protein kinases (MAPK). Such pathways mediate, in part, the known vasoregulatory, anti‐inflammatory, anti‐apoptotic and anti‐proliferative effects of this gas. Exogenous CO delivered at low concentrations is showing therapeutic potential as an anti‐inflammatory agent and as such can modulate numerous pathophysiological states. This review will delve into the biological significance and medical applications of this gas molecule. BioEssays 26:270–280, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Both blood vessels and nerves are guided to their target. Vascular endothelial growth factor (VEGF)A is a key signal in the induction of vessel growth (a process termed angiogenesis). Though initial studies, now a decade ago, indicated that VEGF is an endothelial cell‐specific factor, more recent findings revealed that VEGF also has direct effects on neural cells. Genetic studies showed that mice with reduced VEGF levels develop adult‐onset motor neuron degeneration, reminiscent of the human neurodegenerative disorder amyotrophic lateral sclerosis (ALS). (...) Additional genetic studies confirmed that VEGF is a modifier of motor neuron degeneration in humans and in SOD1G93A mice—a model of ALS. Reduced VEGF levels may promote motor neuron degeneration by limiting neural tissue perfusion and VEGF‐dependent neuroprotection. VEGF also affects neuron death after acute spinal cord or cerebral ischemia, and has also been implicated in other neurological disorders such as diabetic and ischemic neuropathy, nerve regeneration, Parkinson's disease, Alzheimer's disease and multiple sclerosis. These findings have raised growing interest in assessing the therapeutic potential of VEGF for neurodegenerative disorders. BioEssays 26:943–954, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

A cost analysis of the utilization of new expensive vascular grafts is performed, applying the methodology of decision analysis to the theoretical case of a sixty year old male patient undergoing femoropopliteal grafting for limb threatening ischemia. The problem is presented graphically as a decision tree, uncertainties are quantified in terms of probabilities and end outcomes are evaluated in monetary terms. This informations is then utilized to calculate cost values associated with alternative actions.Based on initial cumulative patency figures of (...) the new more expensive grafts and the known performance of the older grafts, the initial high expense for the new grafts is justified economically, if the saphenous vein is not available. This analysis, apart from giving an answer to a specific clinical problem, can be viewed as a general model for cost analysis of surgical procedures. (shrink)

We used computer simulations to study the possible role of the dispersion of cellular coupling, refractoriness or both, in the mechanisms underlying cardiac arrhythmias. Local ischemia was first assumed to induce cell to cell dispersion of the coupling resistance (Case 1), refractory period (Case 2), or both of them (Case 3). Our numerical experiments based on the van Capelle and Durrer model showed that vortices could not be induced by cell to cell variations. With cellular properties dispersed in a (...) patchy way within the ischemic zone, a single activation wave could give rise to abnormal activities. This demonstrates the stability of the wave front under small inhomogeneities. Probabilities of reentry, estimated for the three cases cited above showed that a severe alteration of the coupling resistance may be an important factor in the genesis of reentry. Moreover, use of isochronal maps revealed that vortices were both stable and sustained with an alteration of the coupling alone or combined with a reduction of the action potential duration. Conversely, simulations with reduction of the refractoriness alone, inducing only transient patterns, could exhibit functionally determined reentries. (shrink)

The target article discusses various aspects of the relationship between the sympathetic system and pain. To this end, the patients under study are divided into three groups. In the first group, called (RSD), the syndrome can be characterized by a triad of autonomic, motor, and sensory symptoms, which occur in a distally generalized distribution. The pain is typically felt deeply and diffusely, has an orthostatic component, and is suppressed by the ischemia test. Under those circumstances, the pain is likely (...) to respond to sympatholytic interventions. In a second group, called (SMP) syndrome, the principal symptoms are spontaneous pain, which is felt superficially and has no orthostatic component, and allodynia. These symptoms, typically confined to the zone of a lesioned nerve, may also be relieved by sympathetic blocks. Since the characteristics of the pain differ between RSD and SMP, the underlying kind of sympathetic–sensory coupling may also vary between these cases. A very small third group of patients exhibits symptoms of both RSD and SMP. The dependence or independence of pain on sympathetic function reported in most published studies seems to be questionable because the degree of technical success of the block remains uncertain. Therefore, pain should not be reported as sympathetic function independent until the criteria for a complete sympathetic block have been established and satisfied. (shrink)

In many forms of severe acute brain injury there is an early phase when prognosis is uncertain, followed later by physiological recovery and the possibility of more certain predictions of future impairment. There may be a window of opportunity for withdrawal of life support early, but if decisions are delayed there is the risk that the patient will survive with severe impairment. In this paper I focus on the example of neonatal encephalopathy and the question of the timing of prognostic (...) tests and decisions to continue or to withdraw life-sustaining treatment. Should testing be performed early or later; and how should parents decide what to do given the conflicting values at stake? I apply decision theory to the problem, using sensitivity analysis to assess how different features of the tests or different values would affect a decision to perform early or late prognostic testing. I draw some general conclusions from this model for decisions about the timing of testing in neonatal encephalopathy. Finally I consider possible solutions to the problem posed by the window of opportunity. Decision theory highlights the costs of uncertainty. This may prompt further research into improving prognostic tests. But it may also prompt us to reconsider our current attitudes towards the palliative care of newborn infants predicted to be severely impaired. (shrink)

In eukaryotes, small amounts of nitrite confer cytoprotection against ischemia/reperfusion‐related tissue damage in vivo, possibly via reduction to nitric oxide (NO) and inhibition of mitochondrial function. Several hemeproteins are involved in this protective mechanism, starting with deoxyhemoglobin, which is capable of reducing nitrite. In facultative aerobic bacteria, such as Pseudomonas aeruginosa, nitrite is reduced to NO by specialized heme‐containing enzymes called cd1 nitrite reductases. The details of their catalytic mechanism are summarized below, together with a hypothesis on the biological (...) role of the unusual d1‐heme, which, in the reduced state, shows unique properties (very high affinity for nitrite and exceptionally fast dissociation of NO). Our results support the idea that the nitrite‐based reactions of contemporary eukaryotes are a vestige of earlier bacterial biochemical pathways. The evidence that nitrite reductase activities of enzymes with different cellular roles and biochemical features still exist today highlights the importance of nitrite in cellular homeostasis. (shrink)

The neural transplantation research described by Sinden and colleagues provides part of the rationale for the clinical application of neural transplantation. The authors are asked to clarify their view of the role of the cholinergic system in cognition, to address extrahippocampal damage caused by transient forebrain ischemia, and to consider the effects of delayed neural degeneration in their structure-function analysis.

Ischemic stroke involves numerous and complex pathophysiological mechanisms including blood flow reduction, ionic exchanges, spreading depressions and cell death through necrosis or apoptosis. We used a mathematical model based on these phenomena to study the influences of intensity and duration of ischemia on the final size of the infarcted area. This model relies on a set of ordinary and partial differential equations. After a sensibility study, the model was used to carry out in silico experiments in various ischemic conditions. (...) The simulation results show that the proportion of apoptotic cells increases when the intensity of ischemia decreases, which contributes to the model validation. The simulation results also show that the influence of ischemia duration on the infarct size is more complicated. They suggest that reperfusion is beneficial when performed in the early stroke but may be either inefficacious or even deleterious when performed later after the stroke onset. This aggravation could be explained by the depolarisation waves which might continue to spread ischemic damage and by the speeding up of the apoptotic process leading to cell death. The effect of reperfusion on cell death through these two phenomena needs to be further studied in order to develop new therapeutic strategies for stroke patients. (shrink)

Pain is the single most common reason patients seek care in the emergency department. Given the prevalence of pain as a presenting complaint, one might expect emergency physicians to assign its treatment a high priority; however, pain is often seemingly invisible to the emergency physician. Multiple research studies have documented that the undertreatment of pain, or oligoanalgesia, is a frequent occurrence. Pain that is not acknowledged and managed appropriately causes dissatisfaction with medical care, hostility toward the physician, unscheduled returns to (...) the emergency department, delayed return to full function, and potentially, an increased risk of litigation. Failure to recognize and treat pain may result in anxiety, depression, sleep disturbances, increased oxygen demands with the potential for end organ ischemia, and decreased movement with an increased risk of venous thrombosis. (shrink)

Pain is the single most common reason patients seek care in the emergency department. Given the prevalence of pain as a presenting complaint, one might expect emergency physicians to assign its treatment a high priority; however, pain is often seemingly invisible to the emergency physician. Multiple research studies have documented that the undertreatment of pain, or oligoanalgesia, is a frequent occurrence. Pain that is not acknowledged and managed appropriately causes dissatisfaction with medical care, hostility toward the physician, unscheduled returns to (...) the emergency department, delayed return to full function, and potentially, an increased risk of litigation. Failure to recognize and treat pain may result in anxiety, depression, sleep disturbances, increased oxygen demands with the potential for end organ ischemia, and decreased movement with an increased risk of venous thrombosis. (shrink)

The North American wood frog, Rana sylvatica, endures seasonal whole‐body freezing during the winter and thawing during the spring without sustaining any apparent damage from ice or oxidative stress. Strategies from these frogs may solve the shortage of human donor organs, which is a multidisciplinary problem that can be alleviated by eliminating geographical boundaries. Rana sylvatica deploys an array of molecular and physiological responses, such as glucose production and microRNA regulation, to help it survive the cold. These strategies have been (...) adapted in the lab to impart cryotolerance in liver cells, and the non‐freezing supercooled storage of transplantable rat livers − milestones that have advanced the field toward cryopreserving human donor organs in the clinic. In this review, a case is presented for the use of non‐coding RNAs to decrease oxidative damage of donor organs by activating endogenous antioxidant systems prior to procurement. (shrink)

Injury to the central or peripheral nervous system is often associated with persistent pain. After ischemic injury to the spinal cord, rats develop severe mechanical allodynia-like symptoms, expressed as a pain-like response to innocuous stimuli. In its short-lasting phase the allodynia can be relieved with the [gamma]-aminobutyric acid (GABA)-B receptor agonist baclofen, which also reverses the hyperexcitability of dorsal horn interneurons to mechanical stimuli. Furthermore, there is a reduction in GABA immunoreactivity in the dorsal horn of allodynic rats. Clinical neuropathic (...) pain of peripheral and central origin often cannot be relieved by opiates at doses that do not cause side effects. The loss of sensitivity to opiates may be associated with the up-regulation of endogenous antiopioid substances, such as the neuropeptide cholecystokinin (CCK). CCK and its receptor (CCK-R) protein is normally not detectable in rat dorsal root ganglion cells. After peripheral nerve section, both CCK and CCK-R are up-regulated in the dorsal root ganglia. Furthermore, CI 988, an antagonist of the CCK-B receptor, chronically coadministered with morphine, reduces autotomy, a behavior that may be a sign of neuropathic pain following peripheral nerve section. Thus, opiate insensitivity may be due to the release of CCK from injured primary afferents. Similarly, in the chronic phase of the spinal ischemic model of central pain, the allodynia-like symptom is not relieved by systemic morphine, but is significantly reversed by the CCK-B antagonist. Consequently, up-regulation of CCK and CCK-R in the CNS may also underlie opiate drug insensitivity following CNS injury. Thus, dysfunction of central inhibition involving GABA and endogenous opioids may be a factor underlying the development of sensory abnormalities and/or pain following injury to neural tissue. (shrink)

Celebrated for disproving the traditional view that lack of oxygen at birth (perinatal asphyxia) contributes significantly to cerebral palsy, a 1986 New England Journal of Medicine article by Karin Nelson and Jonas Ellenberg engineered a new consensus in the medical community: that lack of oxygen at birth rarely causes cerebral palsy. We demonstrate that the article's central argument relies on straightforwardly fallacious statistical reasoning, and we discuss significant implications -- e.g. how carefully fetuses are monitored during labor and delivery, expert (...) testimony in malpractice cases, and public policy decisions. (shrink)