Spontaneous propeptide processing of mini-stromelysin-1 mutants blocked by APMA ((4-Aminophenyl)mercuric acetate)

Human stromelysin-1 (SL-1) is a member of the stromelysin subfamily of matrix metalloproteinases (MMPs). The MMPs play a major role in the degradation of the extracellular matrix (ECM) during normal and pathological conditions. SL-1 like the other MMPs can be activated in vitro by the stepwise removal of the propeptide that contains a single unpaired cysteine which coordinates the active site zinc. Other residues in the propeptide also play a role in maintaining the latency of the enzymes. Deletion mutants and single-site amino acid replacements within the propeptide of a carboxyl-terminally truncated stromelysin-1 (mini-SL-1) were constructed and expressed in Escherichia coli to further examine what amino acids within the propeptide of SL-1 are important for maintaining latency. While the natural enzyme displayed some limited tendency to spontaneously (autolytically) convert to lower Mr in a stepwise manner and finally to the fully processed form, all of the truncation mutants of more than 19 amino acids generated in E. coli showed greatly accelerated self-cleavage indicative of diminished stability and/or resistance to proteolysis of the residual propeptide. Mutant Delta63 as well as other mutants in which most of the propeptide had been deleted no longer responded to exposure to the organomercurial APMA by accelerated autolytic processing. Rather, APMA inhibited the autolytic processing in these mutants, further confirming the complexity of the action of this organomercurial in the activation of pro-MMPs.     

Neither L-arginine nor L-NAME affects neurological outcome after global ischemia in cats

BACKGROUND AND PURPOSE: We attempted to determine whether N-nitro-L-arginine methyl ester (L-NAME) would improve neurological outcome and whether L-arginine (L-ARG) would worsen neurological outcome after transient global ischemia. METHODS: Halothane-anesthetized cats (n = 6 for each group) were treated with intravenous saline, L-NAME (5 mg/kg or 10 mg/kg), or L-arginine (300 mg/kg) 30 minutes before 10 minutes of ischemia (temporary ligation of the left subclavian and brachiocephalic arteries with hemorrhagic hypotension to 50 mm Hg). At 30 minutes of reperfusion, cats in the L-ARG group were administered an additional 300 mg/kg dose of intravenous L-arginine. RESULTS: Time (mean +/- SE) to isoelectric electroencephalography was similar among groups (saline, 26 +/- 11 seconds; L-NAME-5, 15 +/- 4 seconds; L-NAME-10, 36 +/- 27 seconds; and L-ARG, 22 +/- 7 seconds). At 72 hours, reperfusion pathological injury was severe and neurological deficit score (mean, range) was similar among groups (saline, 38[11 to 70]; L-NAME-5, 52 [40 to 73]; L-NAME-10, 47 [23 to 70]; and L-ARG, 40 [0 to 79]). CONCLUSIONS: Nitric oxide is not important in the mechanism of brain injury after global ischemia in cats.     

Cardiovascular effects of microinjections of opioid agonists into the ''Depressor Region'' of the ventrolateral periaqueductal gray region

Differentiating the binding properties of applied lectins should facilitate the selection of lectins for characterization of glycoreceptors on the cell surface. Based on the binding specificities studied by inhibition assays of lectin-glycan interactions, over twenty Gal and/or GalNAc specific lectins have been divided into eight groups according to their specificity for structural units (lectin determinants), which are the disaccharide as all or part of the determinants and of GalNAc alpha 1-->Ser (Thr) of the peptide chain. A scheme of codes for lectin determinants is illustrated as follows: (1) F (GalNAc alpha 1-->3GalNAc), Forssman specific disaccharide--Dolichos biflorus (DBL), Helix pomatia (HPL) and Wistaria floribunda (WFL) lectins. (2) A (GalNAc alpha 1-->3 Gal), blood group A specific disaccharide--Codium fragile subspecies tomentosoides (CFT), Soy bean (SBL), Vicia villosa-A4 (VVL-A4), and Wistaria floribunda (WFL) lectins. (3) Tn (GalNAc alpha 1-->Ser (Thr) of the protein core)--Vicia villosa B4 (VVL-B4), Salvia sclarea (SSL), Maclura pomifera (MPL), Bauhinia purpurea alba (BPL) and Artocarpus integrifolia (Jacalin, AIL). (4) T (Gal beta 1-->3GalNAc), the mucin type sugar sequences on the human erythrocyte membrane(T alpha), T antigen or the disaccharides at the terminal nonreducing end of gangliosides (T beta)--Peanut (PNA), Bauhinia purpurea alba (BPL), Maclura pomifera (MPL), Sophora japonica (SJL), Artocarpus lakoocha (Artocarpin) lectins and Abrus precatorius agglutinin (APA).(5) I and II (Gal beta 1-->3(4)GlcNAc)--the disaccharide residue at the nonreducing end of the carbohydrate chains derived from either N- or O-glycosidic linkage--Ricinus communis agglutinin (RCA1), Datura stramonium (TAL, Thorn apple), Erythrina cristagalli (ECL, Coral tree), and Geodia cydonium (GCL). (6) B (Gal alpha 1-->3Gal), human blood group B specific disaccharide--Griffonia(Banderiaea) simplicifolia B4 (GSI-B4). (7) E (Gal alpha 1-->4Gal), receptors for pathogenic E. coli agglutinin, Shiga toxin and Mistletoe toxic lectin-I (ML-I) and abrin-a.     

Pre-Chill Spray of Chicken Carcasses to Reduce Salmonella typhimurium

A test chamber was designed and constructed and prechill chicken carcasses inoculated with Salmonella typhimurium were treated in it. They were sprayed with tap water, 0.85% sodium chloride (NaCl), 5% or 10% trisodium phosphate (TSP), 5% or 10% sodium bisulfate (SBS), 0.1% cetylpyridinium chloride (CPC), or 1% lactic acids (LAC) at 207, 345 or 827 kPa pressure for either 30 or 90 sec exposure time. Samples were taken from carcass wash water to determine the most probable number of Salmonella. Compared to tap water spraying, 0.85% NaCl spraying did not significantly reduce Salmonella. The greatest reductions of S. typhimurium, by 10% TSP, 10% SBS, 0.1% CPC or 1% LAC spraying, were 3.7, 2.4, 1.6 or 1.6 log in 90 sec treatments, respectively.     

Engendering the dread disease: women, men, and cancer

This paper, based on an analysis of cancer articles published in popular periodical literature since the early part of the century, argues that gender has played a key role in medical and popular understandings of cancer. Cancer education, the author finds, has taught women and men different things. Public health materials created with the intention of improving health through education actually send a multiplicity of messages, not all of them helpful. This essay suggests that public health messages targeted by sex are problematic, although perhaps necessary. The paper also contributes to scholarship concerned with the question of how people develop their ideas about risk of disease.     

Digital ischemia and gangrene due to red blood cell aggregation induced by acquired dysfibrinogenemia

Digital gangrene was observed in a patient who had angiographic findings of digital arterial occlusion. The patient's blood showed a marked red blood cell aggregation with rouleaux formation in long chains, which could not be dispersed at shear rates up to 200 sec-1. Studies of the patient's blood revealed the presence of an abnormal fibrinogen capable of aggregating normal red blood cells. This fibrinogen was found by Raman spectroscopy to have an increased alpha-helical content, whereas the beta-sheet content was decreased. Defibrinogenation therapy with ancrod resulted in a dramatic symptomatic relief. The disappearance of the abnormal fibrinogen 6 months later and an absence of a family history indicate that this dysfibrinogenemia was acquired.