In vivo regulation of replicative Legionella pneumophila lung infection by endogenous tumor necrosis factor alpha and nitric oxide

The in vivo role of endogenous tumor necrosis factor alpha (TNF-alpha) and reactive nitrogen intermediates (RNIs) in modulation of growth of Legionella pneumophila in the lung was assessed using a murine model of replicative L. pneumophila lung infection. Intratracheal inoculation of mice with L. pneumophila resulted in induction of endogenous TNF-alpha, which preceded clearance of L. pneumophila from the lung. Inhibition of endogenous TNF-alpha activity, via in vivo administration of TNF-alpha neutralizing antibody, or inhibition of endogenous RNIs, via administration of the nitric oxide (NO) synthetase inhibitor N-monomethyl-L-arginine (NMMA), resulted in enhanced growth of L. pneumophila in the lung at > or = 3 days postinfection (when compared with untreated L. pneumophila-infected mice). Because of the similar kinetics of enhanced pulmonary growth of L. pneumophila in mice treated in vivo with either anti-TNF-alpha antibody or NMMA, the immunomodulatory effect of NO on endogenous TNF-alpha activity in the lung was assessed. Administration of NMMA to L. pneumophila-infected mice resulted in a significant decrease in endogenous TNF-alpha activity in the lung during replicative L. pneumophila infections in vivo. However, administration of exogenous TNF-alpha to NMMA-treated mice failed to significantly enhance clearance of L. pneumophila from the lung. Results of these studies indicate that both endogenous NO and TNF-alpha facilitate resolution of replicative L. pneumophila lung infections and that regulation of L. pneumophila replication by TNF-alpha is mediated, at least in part, by NO.     

Serum amyloid A (SAA): influence on HDL-mediated cellular cholesterol efflux

Normal high density lipoprotein (N-HDL) is remodeled during acute phase (AP) reactions by the association of serum amyloid A (SAA) and the depletion of apolipoprotein (apo) A-I. To determine the impact of this remodeling on HDL function, the capacities of N-HDL and AP-HDL to associate with and promote cholesterol efflux from human monocytic THP-1 cells were compared. THP-1 cells preferentially bound AP-HDL compared with N-HDL. Examination of the AP-HDL particles bound to THP-1 cells revealed a disproportionate association of an apoSAA-enriched, apoA-I-depleted subpopulation compared with the composition of the starting material. However, N-HDL and AP-HDL promoted cholesterol efflux from THP-1 cells equally efficiently and in a dose-dependent manner. When N-HDL was experimentally remodeled with apoSAA to achieve an apoprotein composition similar to that of the preferentially bound particles, cellular cholesterol efflux was reduced by 30%. The remodelling of HDL with apoSAA during the acute phase reaction alters cholesterol efflux only when apoSAA constitutes more than 50% of the HDL protein.     

Keeping secrets: the ethical and legal challenges

Blatant examples of breeches of confidentiality are less common in comparison to the daily indiscretions that occur by members of the health care team or support staff. Yet such breeches of confidentiality are rarely identified as ethical or legal problems and therefore remain unaddressed. To uphold their moral and legal obligation to protect private information, nurses must examine the nature of their obligations and devise strategies to create and maintain a culture that holds health care professionals accountable for their actions.     

Stress in bone adjacent to dental implants

Finite element analysis (FEA) was employed to assess patterns of stress in bone adjacent to an implant after application of loads through an attached distal extension cantilever. Under all loading conditions, the highest stresses occurred at the distal cervical bone margin adjacent to the cantilever. In clinical studies, this is not consistently the site of the greatest bone changes seen radiographically. This suggests that extrapolation of FEA studies to clinical implantology should be approached with caution until further data become available on both mechanical properties of bone and patterns of bone remodelling induced by defined functional stresses in mandible and maxillae.     

99mTc-HMPAO labeled leukocyte SPECT in intracranial lesions

BACKGROUND: Scintigraphy with 111In (indium-111)-oxine or 99mTechnetium-hexamethylpropyleneamine oxime (99mTc-HMPAO) labeled leukocytes has been used to differentiate brain abscess from brain tumor. However, there are false positive or false negative results from planar scintigraphic images. So a more specific and sensitive scintigraphic technique needs to be developed. METHODS: Planar and single photon emission computed tomography (SPECT) images were obtained and reviewed in 14 patients with intracerebral ring-enhancing lesions on computed tomography (CT) or magnetic resonance imaging (MRI). In all patients, diagnosis was confirmed by histopathologic examination. The effect of steroids or antibiotics on scintigraphic finding was examined. RESULTS: Abscess was confirmed in six patients, tumor in six, tuberculoma and cysticercosis in one each, respectively. In all the patients with abscess, SPECT showed increased focal activity irrespective of steroid or antibiotic therapy. Increased radioactivity, which could not be detected on planar images, could be identified in two patients with abscess. In three of the six patients with tumor, radiolabeled leukocytes did not accumulate in the tumor. In the other three patients with tumor, SPECT showed focally increased activity that was less intense than the activity shown in the patients with abscess. CONCLUSIONS: 99mTc-HMPAO labeled leukocyte SPECT is useful for the differential diagnosis of intracerebral ring-enhancing lesions, and the use of steroids or antibiotics does not influence the sensitivity of SPECT. Diagnostic sensitivity of scintigraphy with labeled leukocytes could be improved by SPECT in addition to planar image.     

Non-bilayer lipids are required for efficient protein transport across the plasma membrane of Escherichia coli

The construction of a mutant Escherichia coli strain which cannot synthesize phosphatidylethanolamine provides a tool to study the involvement of non-bilayer lipids in membrane function. This strain produces phosphatidylglycerol and cardiolipin (CL) as major membrane constituents and requires millimolar concentrations of divalent cations for growth. In this strain, the lipid phase behaviour is tightly regulated by adjustment of the level of CL which favours a nonbilayer organization in the presence of specific divalent cations. We have used an in vitro system of inverted membrane vesicles to study the involvement of non-bilayer lipids in protein translocation in the secretion pathway. In this system, protein translocation is very low in the absence of divalent cations but can be enhanced by inclusion of Mg2+, Ca2+ or Sr2+ but not by Ba2+ which is unable to sustain growth of the mutant strain and cannot induce a non-bilayer phase in E. coli CL dispersions. Alternatively, translocation in cation depleted vesicles could be increased by incorporation of the non-bilayer lipid DOPE (18:1) but not by DMPE (14:0) or DOPC (18:1), both of which are bilayer lipids under physiological conditions. We conclude that non-bilayer lipids are essential for efficient protein transport across the plasma membrane of E. coli.     

Urologic applications of multiplanar and three-dimensional computed tomography

The introduction of helical computed tomography (CT) has resulted in improved quality of multiplanar reformations and three-dimensional reconstructions in the chest and abdomen and has made CT angiography a clinical reality. These imaging techniques are useful for evaluating the urinary tract, adding a new dimension to its display, resulting in improved diagnosis of renal and perirenal disease. This article reviews the indications and techniques utilized for multiplanar and three-dimensional CT for urology. The advantages and limitations are discussed, and normal and pathologic findings in the urinary tract illustrated.     

Purification and characterization of constituent testosterone 2 alpha-hydroxylase (cytochrome P450(2)alpha) from mouse liver

Hepatic microsomal testosterone/androstenedione 2 alpha-hydroxylase (i.e., cytochrome P450(2)alpha) was purified from female CD-1 mice. Protein purification was monitored in eluates from Fractogel, DEAE-sephacel, and hydroxylapatite columns at heme absorbing 417 nm and by cytochrome P450 content, reactivity to a monoclonal antibody against female-specific rat cytochrome P450 2C12, and testosterone 2 alpha-hydroxylase activity. The catalytic activity of the purified cytochrome P450(2)alpha, exhibiting a high degree of regioselectivity and stereospecificity, was basically restricted to the 2 alpha-hydroxylation of testosterone and androstenedione; representing > 96% and > 92% of these respective metabolites. Polyclonal antibodies against cytochrome P450(2)alpha exhibited a dose-dependent and very selective inhibition of testosterone 2 alpha-hydroxylation. The specific cytochrome P450 content of the purified cytochrome P450(2)alpha fraction was 12.06 nmol/mg protein. The specific testosterone 2 alpha-hydroxylase activity of the purified protein was 14 nmol/min/nmol cytochrome P450, which was about 60-fold higher than the respective microsomes. The apparent subunit molecular weight of cytochrome P450(2)alpha was 51,000 and the protein appeared as a single band on sodium dodecyl sulfate polyacrylamide gels. The amino-terminal sequence analysis indicates that cytochrome P450(2)alpha is a member of the murine cytochrome P450 2d family.