PubMed · 9263651
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A C Braverman. 1997. Aortic dissection.. https://pubmed.ncbi.nlm.nih.gov/9263651/
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There is increasing evidence that central noradrenaline (NA) transport mechanisms are implicated in the central nervous system complications of acute liver failure. In order to assess this possibility, binding sites for the high affinity NA transporter ligand [3H]-nisoxetine were measured by quantitative receptor autoradiography in the brains of rats with acute liver failure resulting from hepatic devascularization and in appropriate controls. In vivo microdialysis was used to measure extracellular brain concentrations of NA. Severe encephalopathy resulted in a significant loss of [3H]-nisoxetine sites in frontal cortex and a concomitant increase in extracellular brain concentrations of NA in rats with acute liver failure. A loss of transporter sites was also observed in thalamus of rats with acute liver failure. This loss of NA transporter sites could result from depletion of central NA stores due to a reserpine-like effect of ammonia which is known to accumulate to millimolar concentrations in brain in ischemic liver failure. Impaired NA transport and the consequent increase in synaptic concentrations and increased stimulation of neuronal and astrocytic noradrenergic receptors could be implicated in the pathogenesis of the encephalopathy and brain edema characteristic of acute liver failure.
Traumatic injury to axons was modeled in vitro using sympathetic principal neurons from the rat superior cervical ganglion. Neurons were grown as a pure culture on collagen in parallel tracks, with cell somata confined to the center, and neurites occupying the periphery of the culture dish. Growing as fascicles on tracks, the neurites demonstrated periodic varicosities. Neuritic transection was reliably and reproducibly achieved with a motor driven rubber impactor injury device. During a period lasting at least 1 h, dieback involving the proximal neurites averaged 105 +/- 10 microm. This was followed by neurite regeneration, with the injured segment being traversed within 36 h at an average rate of regeneration of 595 +/- 15 microm/day. The distal neurite segments showed degenerative changes within 1 h following transection, with initial receding of neurites progressing to vacuolation, beading, blebbing, and eventual detachment from the underlying matrix. This in vitro model of axonal injury allows neuritic injury to be studied at the cellular and molecular levels, and also provides a unique opportunity to test potential neuromodulatory and neuroprotective strategies.
The role of corticosteroids in the prophylaxis of graft-versus-host disease (GVHD) is not well established. We have conducted a prospective, randomized, open-label, single-center study about the effect of adding methylprednisolone (MP) to the widely used prophylactic regimen consisting of cyclosporine A and methotrexate. A total of 108 consecutive patients treated with allogeneic bone marrow transplantation from an HLA-identical sibling donor for malignant blood disease were entered into the study; 53 patients were randomized to receive and 55 were randomized not to receive prophylactic MP. The dose of MP was 0.5 mg/kg on days 14 to 20, 1 mg/kg on days 21 to 34, 0.5 mg/kg on days 35 to 48, and thereafter the dose was slowly tapered and the administration discontinued on day 110. In the group given prophylactic MP, the incidence of acute GVHD was lower (19% vs 56%, P =.0001), there was a trend toward a lower incidence of chronic GVHD among low-risk patients (P =.06), and during the first 4 months the time spent at hospital was shorter and there were fewer infections. The total amount of MP given was similar in the study groups because of a higher incidence of acute GVHD and its treatment in the group of patients not given prophylactic MP. There were no significant differences between the study groups in relapse rate or survival. In conclusion, the addition of MP to the combination of cyclosporine and methotrexate markedly reduced the incidence of acute GVHD without causing untoward effects. The timing of corticosteroid administration is probably important for the efficacy.