In vivo magnetic resonance imaging of experimental thrombosis in a rabbit model

The process of atherosclerotic plaque disruption has been difficult to monitor because of the lack of an animal model and the limited ability to directly visualize the plaque and overlying thrombus in vivo. Our aim was to validate in vivo magnetic resonance imaging (MRI) of the thrombus formation after pharmacological triggering of plaque disruption in the modified Constantinides animal model of plaque disruption. Atherosclerosis was induced in 9 New Zealand White male rabbits (3 kg) with aortic balloon endothelial injury followed by a high cholesterol (1%) diet for 8 weeks. After baseline (pretrigger) MRI, the rabbits underwent pharmacological triggering with Russell's viper venom and histamine, followed by another MRI 48 hours later. Contiguous cross-sectional T2-weighted fast spin echo images of the abdominal aorta were compared by histopathology. In all animals, aortic wall thickening was present on the pretrigger MRI. On MRIs performed 48 hours after triggering, a histologically confirmed intraluminal thrombus was visualized in 6 (67%) of the 9 animals. MRI data correlated with the histopathology regarding aortic wall thickness (R=0.77, P<0.0005), thrombus size (R=0.82, P<0.0001), thrombus length (R=0.86, P<0.005), and anatomic location (R=0.98, P<0.0001). In vivo, MRI reliably determines the presence, location, and size of the thrombus in this animal model of atherosclerosis and plaque disruption. The combination of in vivo MRI and the modified Constantinides animal model could be an important research tool for our understanding of the pathogenesis of acute coronary syndromes.     

Asiatic acid and corosolic acid enhance the susceptibility of Pseudomonas aeruginosa biofilms to tobramycin

Asiatic acid and corosolic acid are two natural products identified as biofilm inhibitors in a biofilm inhibition assay. We evaluated the activities of these two compounds on Pseudomonas aeruginosa biofilms grown in rotating disk reactors (RDRs) in combination with tobramycin and ciprofloxacin. To determine the ruggedness of our systems, the antibiotic susceptibilities of these biofilms were assessed with tobramycin and ciprofloxacin. The biofilm bacteria produced in the RDR were shown to display remarkable tolerance to 10 mug/ml of ciprofloxacin, thus mimicking the tolerance observed in recalcitrant bacterial infections. These studies further demonstrate that a nonmucoid strain of P. aeruginosa can form a biofilm that tolerates ciprofloxacin at clinically relevant concentrations. Neither asiatic acid nor corosolic acid reduced the viable cell density of P. aeruginosa biofilms. However, both compounds increased the susceptibility of biofilm bacteria to subsequent treatment with tobramycin, suggesting asiatic acid and corosolic acid to be compounds that potentiate the activity of antibiotics. A similar statistical interaction was observed between ciprofloxacin and subsequent treatment with tobramycin.     

Pharmacokinetics of tenofovir in breast milk of lactating rhesus macaques

To study tenofovir transfer into milk, two lactating macaques were given a subcutaneous dose of tenofovir (30 mg/kg of body weight). Peak concentrations and area under the curve values of tenofovir in milk were approximately 3 and approximately 20% of those detected in serum, respectively.     

A noncomparative study of cefprozil at two dose levels in the treatment of acute uncomplicated bacterial sinusitis.

The efficacy and safety of cefprozil at two dose levels were evaluated in 110 patients with acute uncomplicated bacterial sinusitis in an uncontrolled, noncomparative, Phase II trial. Ninety patients received 250 mg of cefprozil (low-dose group) and 20 patients received 500 mg of cefprozil (high-dose group) every 12 hours for ten days. Evaluable patients had symptoms consistent with acute sinusitis, pathogens isolated at pretreatment susceptible to cefprozil, and a radiograph positive for sinusitis within 48 hours before treatment. A satisfactory clinical response was achieved in 34 of 39 evaluable patients (87%) in the low-dose group and in all 16 evaluable patients (100%) in the high-dose group. Pathogens were eradicated in 35 of 39 patients (90%) in the low-dose group and in 15 of 16 patients (94%) in the high-dose group. A total of 140 of 155 pathogens (90%) isolated pretreatment were susceptible to cefprozil. Six patients (7%) in the low-dose group and one patient (5%) in the high-dose group reported at least one adverse clinical event.     

p53 alpha-Helix mimetics antagonize p53/MDM2 interaction and activate p53

Overexpression or hyperactivation of MDM2 contributes to functional inactivation of wild-type p53 in nearly 50% of tumors. Inhibition of p53 by MDM2 depends on binding between an NH(2)-terminal (residues 16-28) p53 alpha-helical peptide and a hydrophobic pocket on MDM2, presenting an attractive target for development of inhibitors against tumors expressing wild-type p53. Here we report that novel p53 alpha-helical peptide mimics based on a terphenyl scaffold can inhibit MDM2-p53 binding in vitro and activate p53 in vivo. Several active compounds have been identified that inhibit MDM2-p53 binding in an ELISA assay with IC(50) of 10 to 20 micromol/L and induce p53 accumulation and activation in cell culture at 15 to 40 micromol/L. These results suggest that p53 alpha-helical mimetics based on the terphenyl scaffold may be developed into potent p53 activators.     

Accessory mitral valve tissue: Appearance on cardiac computed tomography

Accessory mitral valve tissue is an uncommon congenital malformation and a rare cause of left ventricular outflow tract obstruction. Although echocardiography provides a "gold standard" for evaluation of valves, the high temporal and spatial resolutions of computed tomography technology makes it useful in the assessment of valvular structure and function.     

Synthesis of complement components (C3, C2, B and C1-inhibitor) and lysozyme by human monocytes and macrophages

The synthesis of C3, C2, factor B (B) C1-inhibitor and lysozyme has been studied in monocytes and macrophages isolated from the synovial fluids of patients with rheumatoid arthritis. Concentrations of all 5 proteins in culture supernatants were measured by the sandwich ELISA technique. Kinetic studies showed that only lysozyme and C3 could be detected in monocyte culture supernatants on the first day of culture, whereas C2, B and C1-inhibitor were not present until the third day. In contrast all 5 proteins could be detected in the supernatants of macrophage cultures on day 1. In both monocyte and macrophage cultures synthesis of lysozyme and C1-inhibitor continued throughout the culture period, whereas synthesis of C2, B and C3 appeared to be reduced after the fifth day in culture. Quantitative studies showed that the secretion rates of lysozyme (4,700 X 10(3) molecules/cell/hr) was similar in monocytes and macrophages. Synthesis rates for all 4 complement components in monocyte cultures were less than 0.2% of that for lysozyme. Although the synthetic rates were higher in macrophages, even then they constituted less than 2% of the rate for lysozyme. Synthetic rates for complement components, but not lysozyme, were increased by BSA-anti-BSA antigen-antibody complexes and reduced by serum-treated complexes. Although the functional activity of monocyte B was similar to that for serum, the activity of monocyte C2 was 5 times that of serum C2. As C42 formed with monocyte C2 had a half-life of 13.5 min at 30 degrees C, compared with 4.5 min for the enzyme formed with serum C2, it is probable that monocyte C2 is oxidized by the oxygen products of these cells.     

Detection of an apparent homozygous 3120G>A cystic fibrosis mutation on a routine carrier screen

A 28-year-old Caucasian female with no personal or family history of cystic fibrosis (CF) presented for preconception counseling and screening. Cystic fibrosis transmembrane conductance regulator (CFTR) mutation analysis using the Inno-LiPa CFTR assay revealed lack of hybridization for both the wild-type and mutant oligonucleotides for 3120+1G>A. This region was sequenced, and an apparent homozygous 3120G>A mutation was detected. Additional testing revealed an abnormal sweat chloride (77 mmol/L). Review of systems was essentially unremarkable with an absence of sinus symptoms, occasional nonproductive cough, and no features of malabsorption. Physical examination, chest X-ray, and pulmonary function tests were within normal limits. Only two other patients (siblings) with homozygous 3120G>A mutations have been reported (http://www.genet.sickkids.on.ca/cftr/). Both siblings had pancreatic insufficiency, mild pulmonary symptoms, and abnormal sweat chloride levels. Our findings suggest that a homozygous mutation of a G>A conversion at 3120 is associated with abnormal CFTR function and either a mild form of CF or no overt symptoms of disease, emphasizing the difficulties in assigning genotype/phenotype correlation.     

Glutathione, glutathione S-transferase, and transmembrane transport of glutathione conjugate in human neutrophil leukocytes

Glutathione (GSH) conjugation is important in the detoxification of carcinogens and other exogenous electrophilic drugs and chemicals. The conjugation is catalyzed by GSH S-transferase. Neutrophil GSH content was 12.3 +/- 2.5 (mean +/- SD) nmol/10(7) cells, and transferase activity of cytosol preparations was 0.187 +/- 0.035 nmol/min/mg protein with 1-chloro-2,4-dinitrobenzene (CDNB) as substrate. Maximal activity was found at a pH of 7.0 and a temperature of 40 degrees C. Apparent Km of transferase was 1.25 +/- 0.18 mmol/L CDNB, and apparent Vmax was 0.621 +/- 0.22 nmol/min/mg. GSH-CDNB conjugate was quantitated by HPLC in cells and in medium after CDNB exposure. Transport of conjugate from cells to medium increased with CDNB concentration to 50 mumol/L, and kinetic data showed two saturable transport mechanisms with apparent Km of 5.90 mumol/L and 0.265 mumol/L, respectively. Cellular GSH content fell rapidly with CDNB concentration greater than 2.5 mumol/L, and was depleted in a 10-minute incubation at a concentration of greater than 50 mumol/L CDNB. Neutrophils have a significant content of GSH and a significant amount of transferase activity, and transport of GSH conjugate involves two distinct saturable pathways. GSH depletion can be accomplished with a relatively low concentration of an exogenous chemical and could impair the ability of the cells to carry out their phagocytic functions.