Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
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Pneumococcal meningitis resulting from Streptococcus pneumoniae has a death rate of 28% in adults. In severe head injury and stroke, inflammatory changes and intracranial hypertension are improved by induced hypothermia, which also is neuroprotective. We hypothesized that moderate hypothermia ameliorates inflammatory changes in experimental pneumococcal meningitis. ⋯ The influx of leukocytes into the cerebrospinal fluid and levels of tumor necrosis factor alpha in the cerebrospinal fluid were decreased. Cooling the animals 2 hours after meningitis induction to 30.5 degrees C was also protective. We conclude that hypothermia is a new adjuvant approach to reduce meningitis-induced changes, in particular intracranial pressure, in the early phase of the disease.
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J. Cereb. Blood Flow Metab. · Apr 2000
Expression of Fas and Fas ligand after experimental traumatic brain injury in the rat.
Apoptotic cell death plays an important role in the cascade of neuronal degeneration after traumatic brain injury (TBI), but the underlying mechanisms are not fully understood. However, increasing evidence suggests that expression of Fas and its ligand (FasL) could play a major role in mediating apoptotic cell death in acute and chronic neurologic disorders. To further investigate the temporal pattern of Fas and FasL expression after experimental TBI in the rat, male Sprague Dawley rats were subjected to unilateral cortical impact injury. ⋯ These results reveal induction of Fas and FasL expression in the cortex after TBI in the rat. Further, these data implicate an involvement of Fas and FasL in the pathophysiologic mechanism of apoptotic neurodegeneration after TBI. Last, these data suggest that strategies aimed to repress posttraumatic Fas- and FasL-induced apoptosis may open new perspectives for the treatment of TBI.
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J. Cereb. Blood Flow Metab. · Mar 2000
Neural substrate for the effects of passive training on sensorimotor cortical representation: a study with functional magnetic resonance imaging in healthy subjects.
Repetitive passive movements are part of most rehabilitation procedures, especially in patients with stroke and motor deficit. However, little is known about the consequences of repeated proprioceptive stimulations on the intracerebral sensorimotor network in humans. Twelve healthy subjects were enrolled, and all underwent two functional magnetic resonance imaging (fMRI) sessions separated by a 1-month interval. ⋯ A redistribution of SMA activity was observed. The authors demonstrated that passive training with repeated proprioceptive stimulation induces a reorganization of sensorimotor representation in healthy subjects. These changes take place in cortical areas involved in motor preparation and motor execution and represent the neural basis of proprioceptive training, which might benefit patients undergoing rehabilitative procedures.
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J. Cereb. Blood Flow Metab. · Mar 2000
Importance of posttraumatic hypothermia and hyperthermia on the inflammatory response after fluid percussion brain injury: biochemical and immunocytochemical studies.
The purpose of this study was to investigate: 1) the temporal and regional profile of polymorphonuclear leukocyte (PMNL) infiltration after moderate traumatic brain injury using the parasagittal fluid percussion model and 2) the effects of posttraumatic hypothermia (30 degrees C) and hyperthermia (39 degrees C) on the acute and subacute inflammatory response. We hypothesized that posttraumatic hypothermia would reduce the degree of PMNL accumulation whereas hyperthermia would exacerbate this response to injury. In the first series of experiments we quantitated the temporal profile of altered myeloperoxidase activity under normothermic (37 degrees C) conditions (n = 20). ⋯ In contrast, posttraumatic hyperthermia significantly elevated myeloperoxidase activity in the posterior cortical region compared to normothermic values at both 3 hours and 3 days (473.5 +/- 258.4 and 100.11 +/- 27.58 U/g of wet tissue, respectively, P < 0.05 versus controls). These results indicate that posttraumatic hypothermia decreases early and more prolonged myeloperoxidase activation whereas hyperthermia increases myeloperoxidase activity. Temperature-dependent alterations in PMNL accumulation appear to be a potential mechanism by which posttraumatic temperature manipulations may influence traumatic outcome.
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J. Cereb. Blood Flow Metab. · Mar 2000
Rapid tau protein dephosphorylation and differential rephosphorylation during cardiac arrest-induced cerebral ischemia and reperfusion.
The effects of cerebral ischemia/reperfusion on phosphorylation of microtubule-associated tau proteins were assessed in a canine model of cardiac arrest. As tau proteins are phosphorylated by kinases involved in different transduction signal pathways, their phosphorylation state is an excellent marker of neuronal homeostasis and microtubule dynamics. Canine brain tau proteins were characterized by immunoblotting using phosphorylation-dependent antibodies and antisera raised against different amino- and carboxy-terminal tau sequences. ⋯ After 2-hour restoration of spontaneous circulation, a decrease in the electrophoretic mobility was observed, and after 24 hours of reperfusion, a full restoration of the phosphorylation was visualized using phosphorylation-dependent monoclonal antibodies directed against Ser/Thr-Pro sites. However, one particular phosphorylation site involved in tau binding to microtubules, located on Ser262/356, was never fully significantly rephosphorylated, suggesting that microtubule metabolism was still affected after 24 hours of reperfusion. Thus, the sequential and differential recovery of tau phosphorylation after ischemia followed by reperfusion is a useful marker with which to monitor neuronal integrity after brain ischemia.