A change in the cerebrosides and sulfatides in a demyelinating nervous system: Development of the methodology and study of multiple sclerosis and Wallerian degeneration

This report describes a new method for the microanalysis of sphingolipids and its application for the characterization of cerebrosides and sulfatides in multiple sclerosis brain and rat sciatic nerves undergoing Wallerian degeneration. Tissue was extracted with isopropanol/hexane (20 : 78), and the total lipids obtained were subjected to benzoylation-desulfation. A portion of this was directly analyzed by silica-column high performance liquid chromatography for the determination of nonhydroxycerebroside, hydroxycerebroside, nonhydroxysulfatide, and hydroxysulfatide. Another portion was fractionated by thin-layer chromatography, and the spots corresponding to the sphingolipid derivatives were eluted. The material from each spot was analyzed by reverse phase high performance liquid chromatography for its homolog composition. With this new procedure the concentrations and homolog compositions of cerebrosides and sulfatides were measured in plaque, periplaque, and normal-appearing white matter from brains of multiple sclerosis patients and Wallerian degenerated rat sciatic nerves distal to the nerve transection. One piece of plaque studied contained only 1.86, 2.76, 0.60, and 0.45 nmol of nonhydroxycerebroside, hydroxycerebroside, nonhydroxysulfatide and hydroxysulfatide/mg of protein, respectively. These concentrations are less than 1% of those found in normal white matter. Periplaques were found to contain concentrations of these sphingolipids between those of plaque and normal white matter. The levels of these sphingolipids in degenerative nerves were 10–20% below normal the third day after the nerve was severed and about 70% below normal after 10 days. The rate of decrease lessened from ten days to 55 days. The homolog compositions of these sphingolipids in both multiple sclerosis brain and degenerating nerves were similar to those in the control. The implications of these findings and the advantages of this new analytical method are discussed.     

Bolus administration of landiolol, a short-acting, selective beta1-blocker, to treat tachycardia during anesthesia: a dose-dependent study

OBJECTIVES: The purpose of this study was to clarify the clinical efficacy of landiolol, a selective beta(1)-blocker, in patients developing tachycardia during anesthesia. DESIGN: A prospective, randomized, and placebo-controlled study. SETTING: A single university hospital. PARTICIPANTS: Patients undergoing resection of intracranial or maxillofacial tumors under general anesthesia. INTERVENTIONS: Intravenous bolus administration of landiolol. MEASUREMENTS AND MAIN RESULTS: Patients with heart rates exceeding 90 beats/min for more than 5 minutes received an intravenous bolus dose of landiolol. These patients who developed tachycardia were randomized into 4 groups receiving landiolol in the dose of 0, 0.1, 0.2, or 0.3 mg/kg. Heart rate and blood pressure were recorded before drug injection and 1, 3, 5, 7, 10, 15, 20, 25, and 30 minutes after the injection. Heart rate was significantly reduced with each dose of landiolol compared with the placebo group between 3 and 20 minutes after drug injection. The lowest heart rate was 93 +/- 4, 80 +/- 8, 79 +/- 8, and 77 +/- 6 beats/min (mean +/- standard deviation) in the landiolol 0, 0.1, 0.2, and 0.3 mg/kg groups, respectively. On the other hand, reduction of blood pressure was not as remarkable as that of heart rate. Landiolol, 0.1 and 0.2 mg/kg, did not significantly reduce systolic or diastolic blood pressure during the study period, although significant reduction of blood pressure was observed in the landiolol 0.3-mg/kg group between 5 and 10 minutes after drug injection. CONCLUSION: The results showed that bolus administration of landiolol was effective in the treatment of tachycardia during anesthesia in surgical patients. Landiolol was more efficacious in reducing heart rate than blood pressure.     

Uncoupling of vascular endothelial growth factor with nitric oxide as a mechanism for diabetic vasculopathy

The role of VEGF in vascular disease is complicated. Vascular endothelial growth factor (VEGF) expression can be deleterious in diabetic vasculopathy, especially in kidney and retina. In contrast, VEGF seems to be renoprotective in nondiabetic renal disease. VEGF exerts it biologic effects in association with nitric oxide (NO), yet it is known that NO bioavailability is reduced in diabetes. Thus, it was hypothesized that this diverse biologic effect of VEGF on diabetic vasculopathy is due to uncoupling of VEGF with NO. VEGF stimulated NO production in a dose-dependent manner in bovine aortic endothelial cells (BAEC), and this was inhibited by either high glucose or Nomega-nitro-l-arginine methyl ester (L-NAME) treatment. Endothelial NO synthase phosphorylation by VEGF was also inhibited by high glucose. It is interesting that both high glucose and L-NAME enhanced the proliferative response of endothelial cells, which was prevented by an NO donor. Furthermore, high glucose as well as L-NAME stimulated VEGF and kinase-insert domain receptor (KDR) (VEGF receptor 2) mRNA expression in BAEC. These data suggest that the uncoupling of VEGF with NO enhances endothelial cell proliferation via the KDR pathway. Compatible with these findings, a KDR antagonist blocked this response. In addition, a VEGF mutant, which binds only KDR, induced extracellular signal-regulated kinase (ERK) activation, and inhibition of ERK completely blocked endothelial cell proliferation under this condition, suggesting a role of the KDR-ERK1/2 pathway on endothelial cell proliferation. In conclusion, high glucose causes an uncoupling of VEGF with NO, which enhances endothelial cell proliferation via activation of the KDR-ERK1/2 pathway. These results may provide new insights into the understanding of the mechanism of diabetic vascular disease.