Plasma from women with preeclampsia increases endothelial cell nitric oxide production

In preeclampsia, a factor in the maternal circulation alters endothelial function via a reduction in nitric oxide synthesis. We measured the in vitro effects of 2% plasma from women with preeclampsia, compared with 2% plasma from normotensive pregnant women, on cultured endothelial cell nitrite production and nitric oxide synthase activity. On finding differential effects, we measured the effects on cellular viability (assessed by lactate dehydrogenase levels) and performed a time course study. Endothelial cell nitrite production was found to be higher after exposure to plasma from the preeclamptic group than the normotensive pregnant group. The effects of long-term exposure (120 hours) were similar to those of short-term exposure (24 hours). In addition, nitric oxide synthase activity was significantly greater after exposure to preeclamptic plasma than after exposure to normotensive pregnant plasma. No differential effect on cellular viability was found. Contrary to our hypothesis, exposure of endothelial cells to preeclamptic plasma resulted in increased nitric oxide production and nitric oxide synthase activity.     

Simultaneous microdialysis in brain and blood of the mouse: extracellular and intracellular brain colchicine disposition

A simultaneous brain and blood microdialysis system was developed to study the passage of colchicine through the blood-brain barrier in the mouse. Colchicine was administered as a bolus in the jugular vein (1.5 mg kg-1) and its hippocampal extracellular fluid (ECF) and blood kinetics were determined over a 4 h period using two microdialysis probes, one in the dorsal hippocampus, the other in the inferior vena cava. Colchicine rapidly diffused into the hippocampus (maximum concentration in the first dialysate sample) and brain and blood concentrations declined in parallel, suggesting rapid equilibration between these two compartments. However, only 6. 7% of total blood colchicine, 14% of unbound colchicine was present in the hippocampus suggesting that the P-glycoprotein efflux pump limits colchicine uptake by the brain. We also found, using conventional tissue homogenate analysis in parallel, that the concentration of colchicine in the hippocampal ECF was 10 times less than that in the intracellular space and that the hippocampus colchicine concentration was 2.8 times higher than that of the rest of the brain. This study shows that the simultaneous brain and blood microdialysis can be used to measure the passage of colchicine through the blood-brain barrier and to estimate the brain extra- and intracellular distribution of colchicine.     

A non-ouabain Na/K ATPase inhibitor isolated from bovine hypothalamus. Its relation to hypothalamic ouabain

We have isolated from bovine hypothalamic and pituitary tissue the sodium pump inhibitor HHIF that is structurally different from ouabain. By mass spectrometric analysis this purified factor revealed a single unique molecular ion with an accurate mass of 412.277 and a mass spectra different from ouabain. It has been previously shown that HHIF inhibits the Ca2+-ATPase of the plasma membrane of synaptosomes. HHIF increases free calcium levels in cultured rat mesangial cells as well as mesangial cell contraction and proliferation. With the same purification procedure we have isolated in parallel HHIF and Ouabain from central nervous tissue. Ouabain elutes prior to HHIF in the final purification HPLC systems. This endogenous Ouabain has, in all the systems tested, the same chromatographic behavior that synthetic cold or [3H] Ouabain.     

Meningitis due to Bacillus cereus in an infant with Reye syndrome

OBSERVATION: We report the case of a 2.5-month-old infant with Bacillus cereus meningitis who was initially admitted for Reye syndrome. Gram positive bacteria was isolated in CSF and shown to be located inside the polymorphonuclears. This pathogen was further identified by sequencing of the 16S RNA. Early administration of imipenem in association with amikacin resulted in a rapid recovery. No obvious immune defect or invasive procedure could be assessed. CONCLUSION: Although Bacillus cereus is mainly associated with contamination, repeated isolations of this bacteria may be due to true infection.     

Quadrupolar metal ion NMR studies of metalloproteins

We present a summary of the quadrupolar metal ion NMR studies of metalloproteins conducted in our laboratory in recent years. The approaches we employ can be subdivided into two categories: (i) the use of low-frequency metal nuclei to probe metal ion binding sites in small proteins, exemplified by 43Ca NMR studies of alpha-lactalbumins and calcium-binding lysozymes, and (ii) the novel detection of the central transition of half-integer quadrupolar nuclei of moderate frequency bound to large metalloproteins, typified by 27Al, 45Sc, 69,71Ga, and 51V NMR studies of the transferrins. We highlight the chemical information regarding the nature of metal ion binding sites that can be obtained from this technique and emphasize the salient parameters that an investigator must consider to successfully apply quadrupolar NMR to the study of biological macromolecules.