Surface localization of Helicobacter pylori urease and a heat shock protein homolog requires bacterial autolysis.

Helicobacter pylori is a gram-negative bacterium which causes chronic gastritis and is associated with peptic ulcer disease, gastric carcinoma, and gastric lymphoma. The bacterium is characterized by potent urease activity, thought to be located on the outer membrane, which is essential for survival at low pH. The purpose of the present study was to investigate mechanisms whereby urease and HspB, a GroEL homolog, become surface associated in vitro. Urease, HspB, and catalase were located almost exclusively within the cytoplasm in fresh log-phase cultures assessed by cryo- immunoelectron microscopy. In contrast, significant amounts of surface-associated antigen were observed in older or subcultured preparations concomitantly with the appearance of significant amounts of extracellular antigen, amorphous debris, and membrane fragments. By use of a variety of biochemical methods, a significant fraction of urease and HspB was associated with the outer membrane in subcultured preparations of H. pylori. Taken together, these results strongly suggest that H. pylori cells undergo spontaneous autolysis during culture and that urease and HspB become surface associated only concomitant with bacterial autolysis. By comparing enzyme sensitivity to flurofamide (a potent, poorly diffusible urease inhibitor) in whole cells with that in deliberately lysed cells, we show that both extracellular and intracellular urease molecules are active enzymatically. Autolysis of H. pylori is an important phenomenon to recognize since it likely exerts significant effects on the behavior of H. pylori. Furthermore, the surface properties of H. pylori must be unique in promoting adsorption of cytoplasmic proteins.     

Low dose intrathecal morphine facilitates early extubation after cardiac surgery: results of a retrospective continuous quality improvement audit

PURPOSE: To document one centre's experience with a multimodal analgesic approach, with or without low dose intrathecal morphine (ITM), in facilitating "fast-track" recovery in patients undergoing cardiac surgery. METHODS: Records of 131 consecutive patients who underwent first time elective cardiac surgery during a four-month period in 2000 were reviewed. Patients were divided into two groups: those receiving and those not receiving preoperative low dose ITM (< 5 microgxkg(-1)) as part of a multimodal analgesic technique. Demographic and surgical characteristics, postoperative morphine use, time to extubation and requirement for antiemetics were recorded. RESULTS: Overall, 75% of patients were extubated within two hours, and 93% within six hours. Fifty-five patients received, and 76 did not receive, ITM (mean +/- SD 259 +/- 53 microg) along with a multimodal analgesic technique (parasternal infiltration, acetaminophen and indomethacin, and postoperative i.v. morphine). Anesthetic technique involved modest dose opioids, volatile agent and propofol infusion. The groups were similar with respect to preoperative, intraoperative and anesthetic characteristics. Mean extubation time for fast-track patients receiving vs not receiving ITM was 75 +/- 65 vs 117 +/- 85 min (P = 0.003). Intravenous morphine use for the first 12 hr after surgery was also reduced in the ITM group (4.6 +/- 4.1 vs 10.0 +/- 14.8 mg, P = 0.009). There was no difference in rescue antiemetic or antipruritic requirements, failed fast-tracking, or serious adverse events. CONCLUSIONS: Multimodal postoperative analgesia allowed for uneventful early extubation and low opioid requirements. Low dose ITM further facilitated early extubation, and reduced postoperative analgesic requirements.     

Administration of a small molecule tissue factor/factor VIIa inhibitor in a non-human primate thrombosis model of venous thrombosis: effects on thrombus formation and bleeding time

INTRODUCTION: Pharmacological treatment of deep vein thrombosis (DVT) in the future may target inhibitors of specific procoagulant proteins. This study used a non-human primate model to test the effect of PHA-798, a specific inhibitor of the tissue factor/Factor VIIa complex (TF/VIIa), on venous thrombus formation. MATERIALS AND METHODS: PHA inhibits the TF/VIIa complex with an IC(50) of 13.5 nM (K(i) 9 nM) and is more than 2000-fold selective for the TF/VIIa complex with respect to IC(50)s for factor Xa and thrombin. In the model, a thrombogenic surface was introduced into the vena cava of a primate, and the amount of thrombus accumulated after 30 min was determined. RESULTS: PHA-798 reduced thrombus formation on the thrombogenic surface in a dose-dependent manner (56+/-1.9% and 85+/-0.3% inhibition with 100 and 200 microg/kg/min PHA-798, respectively) indicating that the model is sensitive to TF/VIIa inhibition. Treatment with 1 mg/kg intravenous (IV) acetyl salicylic acid (ASA) resulted in only a slight (4-12%), non-significant inhibition of thrombus formation. However, the combination of 100 microg/kg/min PHA-798 and 1 mg/kg ASA resulted in an 89% inhibition of thrombus formation. Additionally, while ASA alone increased bleeding time (BT) from 3.3 min at baseline to 4.6 min following treatment, addition of PHA-798 (100 microg/kg/min) to ASA did not significantly increase the BT further (4.7 min). CONCLUSIONS: The results of this study indicate that inhibition of TF/VIIa may be safe and effective for the prevention of the proprogation of venous thrombosis and that the combination of ASA and PHA may provide increased efficacy with little change in safety.     

Design, synthesis, and crystal structure of selective 2-pyridone tissue factor VIIa inhibitors

Targeted 2-pyridones were selected as tissue Factor VIIa inhibitors and prepared from 2,6-dibromopyridine via a multistep synthesis. A variety of chemical transformations, including regioselective nucleophilic addition, selective nitrogen alkylation, and a Suzuki coupling, afforded the targeted tissue Factor VIIa inhibitors. The pyridone core was selected as a replacement for the pyrazinone core of noncovalent tissue Factor VIIa inhibitors and designed such that their substitution pattern would occupy and interact with the S(1), S(2), and S(3) pockets of the tissue Factor VIIa enzyme. These compounds were tested in several serine protease enzyme assays involved in the coagulation cascade exhibiting modest activity on tissue Factor VIIa with excellent selectivity over thrombin and Factor Xa. Finally, an X-ray crystal structure of inhibitor 14a bound to tissue Factor VIIa was obtained and will be described.     

Hormonal regulation of radioiodide uptake activity and Na+/I- symporter expression in mammary glands

The observation that radioiodide uptake (RAIU) activity, mediated by the Na+/I- symporter (NIS), is significantly increased in lactating breast suggests that RAIU and NIS expression in mammary gland are modulated by hormones involved in active lactation. We showed that both the NIS expression level and RAIU in rat mammary gland are maximal during active lactation compared to those in the mammary glands of virgin and pregnant rats as well as the involuting mammary gland. In the lactating mammary gland, NIS is clustered on the basolateral membrane of alveolar cells as a lesser glycosylated form than NIS in thyroid. The RAIU of lactating mammary gland was partially inhibited by treatment with a selective oxytocin antagonist or bromocriptine, an inhibitor of PRL release. These findings suggest that RAIU and NIS expression in mammary gland are at least in part modulated by oxytocin and PRL. Indeed, we showed that NIS messenger ribonucleic acid level was increased in a dose-dependent manner by oxytocin and PRL in histocultured human breast tumors.     

A highly immunoreactive peptide fragment of human luteinizing hormone alpha subunit, discerned with a new, "sequence-specific" radioimmunoassay.

hLHa, whose primary amino acid sequence is known, was reduced and s-carboxymethylated (RCM) to remove secondary and teriary structure. RCM-hLHa was utilized for development of a "sequence specific" ria. RCM-hLHa ria revealed that the NH2-terminal tryptic peptide of hLHa (consisting of only 32 amino acid residues) was nearly as immunoreactive as the entire RCM-hLHa molecule (consisting of 89 residues). No other tryptic peptide was immunoactive. Reduced and s-carbamidomethylated hLHa, differing only slight in structure from RCM-hLHa, was weakly active in the RCM-hLHa ria, demonstrating the utility of this ria for precise study of structure-immunologic activity relationships.