Using the techniques of two-dimensional crystallization on supported lipid bilayers together with computer image processing, two distinct two-dimensional crystal types of staphylococcal alpha-toxin complex are formed depending on the presence or absence of Ca2+ ions. Without Ca2+, these are hexagonally packed (in A, a = b = 89.5 +/- 2.5 A; theta = 119.7 degrees) With Ca2+ present, rectangular crystal packing is seen (in A, a = 114.8 +/- 1.6 A, b = 140.2 +/- 0.7 A; theta = 89.1 degrees). A third, banded crystal type is also seen which is interpreted as a side-to-side packing of regular tubules. We use these tubular crystals for cross-correlation searches with top and side-on views of the complex from single particle reconstructions, and with the repeating units from the two-dimensional crystal types. The results lead us to propose a model in which the different two-dimensional crystal types are formed as a result of alpha-toxin hexamers packing in different orientations. In the hexagonal crystals the hexamers lie end-on with a 6-fold axis in projection. On the addition of Ca2+, the hexamers reorient to lie tilted with respect to the support, thus giving rise to a rectangular projection.

Bacterial Toxins↗

PubMedDate not supplied

Isolated intrathoracic injury with air bag use.

The restrained (air bag and seatbelt) driver of a vehicle involved in a high-speed motor-vehicle accident sustained a tear of the thoracic aorta with no signs of external injury. Air bag deployment may mask significant internal injury, and a high index of suspicion is warranted in such situations.

Accidents, Traffic↗

PubMedDate not supplied

Taurine modulates catalase, aldehyde dehydrogenase, and ethanol elimination rates in rat brain.

Chronic administration of either the sulphonated amino acid taurine (0.32 or 0.62 g/kg for 2 weeks) or the catalase inhibitor, 3-amino, 1,2,4-triazole (AT: 0.5 or 1.0 g/kg for 5 days) significantly reduced catalase activities both in the brain and liver of male Wistar rats. The total brain activity of aldehyde dehydrogenase was significantly increased after the lower dose of taurine and after administration of both doses of AT. Hepatic alcohol dehydrogenase activity was not altered by either AT or taurine administration. In taurine-supplemented rats, a significant increase in the ethanol elimination rates (EER) was discernible in the livers after a 2 g/kg dose of ethanol. In contrast, significant decreases in the EER were observed in both plasmas and livers of rats in which catalase was inhibited by AT. However, the brain EERs were comparable in both catalase-inhibited and taurine-supplemented rats, both showing a decrease by comparison to controls. The similar psychopharmacological effects induced by both of these compounds on ethanol-induced effects might indicate that this is mediated in part via the catalase pathway. Since both catalase and the EERs are diminished in the brain after the administration of either of these compounds, this may be an important factor in the moderation of ethanol-induced behaviour.

Aldehyde Dehydrogenase↗

PubMedDate not supplied

Isoforms of transferrin in psoriasis patients abusing alcohol.

The different isoforms of transferrin have been quantified by isoelectric focusing in the sera of psoriasis patients with and without a history of abusing alcohol. In both male and female psoriasis subjects abusing alcohol, there were significant increases in the 2-sialylated forms by comparison to the control subjects. Psoriasis patients who had no evidence of alcohol abuse had similar profile for the isoforms of transferrin to that of the controls. Other groups of patients with alcohol-induced tissue damage, i.e. liver, brain or muscle, used as positive controls, similarly showed significant increases in the 2-sialylated forms, by comparison to controls. These results substantiate the current use of carbohydrate-deficient transferrin as a sensitive marker of alcohol abuse, particularly in subjects not drinking in excess of 60 g of ethanol/day but showing alcohol-related psoriasis.

Adult↗