Aorto-left atrial fistula in prosthetic aortic endocarditis

Aortic valve endocarditis commonly leads to the formation of a root abscess, but fistulae are uncommon. The echocardiographic findings in a patient with Streptococcus viridans endocarditis of a prosthetic aortic valve associated with a fistula between the aorta and the left atrium are presented. The diagnosis was made by transthoracic echocardiography, although the transesophageal study gave higher resolution views and allowed a more confident exclusion of mitral valve involvement.     

Gene expression in brain during cuprizone-induced demyelination and remyelination

When C57BL/6J mice, 8 weeks of age, received 0.2% Cuprizone in their diet, extensive demyelination in corpus callosum was detectable after 3 weeks, and there was massive demyelination by 4 weeks. As expected, the accumulation of phagocytically active microglia/macrophages correlated closely with demyelination. When Cuprizone was removed from the diet, remyelination was soon initiated; after 6 weeks of recovery, myelin levels were near-normal and phagocytic cells were no longer prominent. Steady-state levels of mRNA for myelin-associated glycoprotein, myelin basic protein, and ceramide galactosyltransferase were already profoundly depressed after 1 week of Cuprizone exposure and were only 10-20% of control values after 2 weeks. Unexpectedly, upregulation of mRNA for these myelin genes did not correlate with initiation of remyelination but rather with accumulation of microglia/macrophages. After 6 weeks of exposure to Cuprizone, mRNA levels were at control levels or higher-in the face of massive demyelination. This suggests that in addition to effecting myelin removal, microglia/macrophages may simultaneously push surviving oligodendroglia or their progenitors toward myelination.     

On the relationship between the mitochondrial inner membrane anion channel and the adenine nucleotide translocase

The mitochondrial inner membrane anion channel (IMAC) is a transport pathway which is believed to be involved in mitochondrial volume homeostasis. The protein, however, has not been identified. In this paper, we examine the relationship between IMAC and the adenine nucleotide translocator. Many inhibitors of the adenine nucleotide translocase are shown to block IMAC, including Cibacron blue 3GA, bromcresol green, alizarin red S, agaric acid, palmitoyl-CoA, and the fluorescein derivatives erythrosin B, erythrosin isothiocyanate, rose bengal, and eosin Y. The following evidence suggests that Cibacron blue, agaric acid, and palmitoyl-CoA inhibit by binding to a common site. 1) They all only partially block the transport of small anions such as Cl-, NO3-, and HCO3-, but completely block the transport of larger anions such as malonate. 2) They decrease the IC50 values of each other in a manner consistent with competitive binding. 3) N-Ethylmaleimide decreases their IC50 values by a similar extent. 4) Inhibition by all shows no dependence on matrix pH and only a small dependence on medium pH. It is suggested that these agents may selectively bind to an open state of IMAC and inhibit by decreasing its conductance. The physiological nucleotides CoA, NAD+, NADH, NADP+, NADH, and ATP do not inhibit; in fact, IMAC is shown to transport ATP. Despite these similarities between IMAC and the adenine nucleotide translocase, IMAC appears to be a separate entity, since some of the IC50 values differ by up to 8-fold, and carboxyatracyloside, the most selective inhibitor of the adenine nucleotide translocase, has no effect on IMAC. In addition, IMAC is also able to transport AMP, while the adenine nucleotide translocase does not.     

Studies on the efficacy of hyperbaric rendering procedures in inactivating bovine spongiform encephalopathy (BSE) and scrapie agents

The efficacy of the procedures in use at the two rendering plants in the Netherlands was assessed on a laboratory-scale using procedures that simulated the pressure cooking part of the rendering process. A pool of bovine spongiform encephalopathy (BSE)-infected brainstem from the United Kingdom and a pool of scrapie-infected brainstem from Dutch sheep were used to spike the rendering materials. The mixtures were subjected to various time-temperature combinations of hyperbaric heat treatment related to the conditions used in Dutch rendering plants in the early 1990s, and to the combination of 20 minutes at 133 degrees C required by the EU Directive on rendering of 1996. The efficacy of the procedures in inactivating BSE or scrapie infectivity was measured by titrating the materials before and after heat treatment in inbred mice, by combined intracerebral and intraperitoneal inoculations at limiting dilutions. Two independent series of experiments were carried out. The design of the study allowed for minimum inactivations of up to 2.2 log (2.0 in the second series) to be measured in the diluted infective material and 3.1 log in the undiluted material. After 20 minutes at 133 degrees C there was a reduction of BSE infectivity of about 2.2 log in the first series (with some residual infectivity detected), and in the second series more than 2.0 log (with no residual infectivity detected). With undiluted brain material there was an inactivation of about 3.0 log (with some residual infectivity detected). With the same procedure, scrapie infectivity was reduced by more than 1.7 log in the first series and by more than 2.2 log in the second series. With undiluted brain material there was an inactivation of more than 3.1 log. In each case no residual scrapie infectivity was detected. The BSE agent consistently appeared to be more resistant to heat inactivation procedures than the scrapie agent, particularly at lower temperatures and shorter times.