Gamma 3 gene-disrupted mice selectively deficient in the dominant IgG subclass made to bacterial polysaccharides undergo normal isotype switching after immunization with polysaccharide-protein conjugate vaccines

Bacterial polysaccharides (PS) are T-independent type 2 Ags that elicit restricted Ab responses of IgM and IgG3 in mice and IgM and predominantly IgG2 in humans. Immunodeficiency in the dominant IgG subclass made to PS is associated with chronic sinus and pulmonary infections with PS-encapsulated bacteria. To elucidate the biologic role of the dominant IgG subclass in the immune response to PS and to make an animal model of human IgG subclass deficiency, we generated mice with a targeted disruption of the exon encoding the CH1 domain of the gamma 3 heavy-chain constant region gene. Homozygotes had no detectable serum IgG3, and their splenocytes did not produce IgG3 after LPS stimulation. IgG3(-/-) mice immunized with PS from Pseudomonas aeruginosa LPS O-side chain or Streptococcus pneumoniae type 19F capsule did not produce any IgG3 anti-PS Abs, in contrast to wild-type mice in which IgG3 was the major IgG subclass. Immunizing both wild-type and IgG3(-/-) mice with 19F PS-protein conjugate elicited IgG1 Abs. We conclude that IgG3(-/-) mice have a selective deficiency in the dominant murine IgG subclass made to T-independent type 2 Ags and may be a useful animal model of IgG subclass deficiency. In addition, we show that the anti-PS Ab class switching to IgG1 that occurs when mice are immunized with a PS-protein conjugate vaccine does not require sequential Ig expression or an intact, upstream gamma 3 heavy-chain gene.     

Synthesis and structure-activity relationships of 2-pyridones: II. 8-(Fluoro-substituted pyrrolidinyl)-2-pyridones as antibacterial agents

The 8-position side chain of 2-pyridones is believed to be involved in the binding with bacterial DNA gyrase to form the ternary complex, making them very important for the activity of 2-pyridones. A series of 2-pyridones having fluoro-substituted amines at the 8-position has been synthesized and their antibacterial activities and parmacokinetic properties are reported.     

Appetite suppressant drugs as inhibitors of human cytochromes P450: in vitro inhibition of P450-2D6 by D- and L-fenfluramine, but not phentermine

BACKGROUND: We compared our results with bullous vs diffuse emphysema by performing a bilateral thoracoscopic stapled volume reduction technique in 15 patients (age 45-80, 10 males, five females). METHODS: Eight patients demonstrated bullous emphysema and seven patients diffuse emphysema. Lung reduction was performed with a bilateral thoracoscopic stapled technique utilizing bovine pericardium in the supine position. RESULTS: Comparison of the bullous versus diffuse groups revealed no significant differences in means for the following variables: length of air leak (7.5 vs 3.3 days); length of stay (8.1 vs 6.5 days); pre-op FEV1, (23% vs 22%); pre-op dyspnea index (3.4 vs 3.6). At 3 months the bullous subset had a highly significant improvement (p < 0.007) in FEV1 (88%) compared with the diffuse subset FEV1 (59%). CONCLUSIONS: These early results suggest that patients with bullous emphysema are at no greater risk and demonstrate a significantly greater improvement in FEV1 than patients with diffuse emphysema.     

The RSNA-AUR-ARRS introduction to research program for 2nd year radiology residents: effect on career choice and early academic performance. Radiological Society of North America. Association of University Radiologists. American Roentgen Ray Society

STUDY OBJECTIVE: To determine whether quantitative measurement of end-tidal carbon dioxide (ETCO2) can differentiate between cardiac and obstructive causes of respiratory distress. DESIGN: Prospective observational study. SETTING: Emergency department (ED) of a tertiary care hospital. PATIENTS: Adult patients who presented to the ED with moderate-to-severe dyspnea. Patients were excluded if they were unable to cooperate with the performance of peak expiratory flow rate (PEFR) or ETCO2 tests, were younger than 18 years of age, or had received prehospital intervention for their respiratory distress. INTERVENTIONS: Physicians obtained an ETCO2 level and PEFR prior to ED pharmacologic intervention. A hand-held capnometer with digital read-out was used to obtain the ETCO2 level. The patient's age, sex, initial vital signs, breath sounds and medication history, the presence or absence of diaphoresis and/or orthopnea, the duration of symptoms, the chest radiograph interpretation, and final diagnosis were also recorded. MEASUREMENTS and RESULTS: Forty-two patients were eligible for inclusion in the analysis. The mean ETCO2 level was 31.1+/-9.4 mm Hg; the mean PEFR was 161.3+/-53.1 L/min. The ETCO2 levels for pulmonary edema/congestive heart failure (CHF) patients differed significantly from those of asthma/COPD patients (27.1+/-7.8 mm Hg vs 33.4+/-9.6 mm Hg; p=0.0375). However, no single ETCO2 level was found to be a reliable predictor of diagnosis. CONCLUSION: ETCO2 levels for pulmonary edema/CHF patients differ significantly from those of asthma/COPD patients. However, no single ETCO2 level reliably differentiates between the two disease processes.     

Impairment and disability: their relation during stroke rehabilitation

Migration of non-volatile and volatile compounds from 'microwave and roasting bags' (MRB), made of Nylon 6,6 (and some Nylon 6), into chicken meat, skin, and juices during roasting (200 degrees C/2 h) in a conventional oven was determined. For measurement of migration of non-volatile compounds, cooked chicken was freeze-dried, extracted with methanol after addition of 2-azacyclononane (internal standard) and the extract cleaned-up using liquid-solid adsorption chromatography (silica gel). High performance liquid chromatography (HPLC) in the reverse phase mode using a linear gradient of methanol in water was used to quantify seven Nylon 6 and Nylon 6,6 cyclic monomers and oligomers of molecular mass up to 678 daltons. Migration into chicken was 7.48 micrograms/g (8.26 mg/bag; 3.94 micrograms/cm2), 16% of the total non-volatile compounds contained in the MRB material. Individual migrants were also quantified. Migration of one volatile compound, 2-cyclopentyl cyclopentanone, into the roast chicken parts was measured. Extraction with diethyl ether, using a modified Likens-Nickerson system of concurrent steam distillation-solvent extraction with an internal standard (cyclohexanone) was performed for 10 h. Gas chromatography/mass spectrometry (GC/MS) in the selected ion mode (SIM) was used for quantification. An average of 14.0 (+/- 4.36) micrograms/bag (or micrograms/chicken) migrated, being 0.08% of the total 2-cyclopentyl cyclopentanone present in MRB. Loss of volatile compounds to the atmosphere is believed to have occurred since there was another, more volatile compound (cyclopentanone), present in MRB, at levels higher than 2-cyclopentyl cyclopentanone, but this was not detected in roast chicken. In general, the transference of MRB components into roast chicken can be considered not to present a hazard.     

An in vitro model of human red blood cell production from hematopoietic progenitor cells

Hemoglobinopathies, such as beta-thalassemias and sickle cell anemia (SCA), are among the most common inherited gene defects. Novel models of human erythropoiesis that result in terminally differentiated red blood cells (RBCs) would be able to address the pathophysiological abnormalities in erythrocytes in congenital RBC disorders and to test the potential of reversing these problems by gene therapy. We have developed an in vitro model of production of human RBCs from normal CD34(+) hematopoietic progenitor cells, using recombinant growth factors to promote terminal RBC differentiation. Enucleated RBCs were then isolated to a pure population by flow cytometry in sufficient numbers for physiological studies. Morphologically, the RBCs derived in vitro ranged from early polylobulated forms, resembling normal reticulocytes to smooth biconcave discocytes. The hemoglobin pattern in the in vitro-derived RBCs mimicked the in vivo adult or postnatal pattern of beta-globin production, with negligible gamma-globin synthesis. To test the gene therapy potential using this model, CD34(+) cells were genetically marked with a retroviral vector carrying a cell-surface reporter. Gene transfer into CD34(+) cells followed by erythroid differentiation resulted in expression of the marker gene on the surface of the enucleated RBC progeny. This model of human erythropoiesis will allow studies on pathophysiology of congenital RBC disorders and test effective therapeutic strategies.     

Transferable, plasmid-mediated vanB-type glycopeptide resistance in Enterococcus faecium

An approximately 60-kb transferable, vanB-carrying plasmid has been identified in a clinical Enterococcus faecium strain. A similar plasmid has been observed in an unrelated E. faecium strain, suggesting that plasmid transfer of vanB operons occurs in nature and plays a role in the dissemination of VanB-type resistance among strains of E. faecium.     

National Institutes of Health support for research and training: future of pediatrician scientists

Agrobacterium tumefaciens transfers part of its Ti plasmid, the T-DNA, to plant cells during tumorigenesis. It is routinely used for the genetic modification of a wide range of plant species. We report that A. tumefaciens can also transfer its T-DNA efficiently to the filamentous fungus Aspergillus awamori, demonstrating DNA transfer between a prokaryote and a filamentous fungus. We transformed both protoplasts and conidia with frequencies that were improved up to 600-fold as compared with conventional techniques for transformation of A. awamori protoplasts. The majority of the A. awamori transformants contained a single T-DNA copy randomly integrated at a chromosomal locus. The T-DNA integrated into the A. awamori genome in a manner similar to that described for plants. We also transformed a variety of other filamentous fungi, including Aspergillus niger, Fusarium venenatum, Trichoderma reesei, Colletotrichum gloeosporioides, Neurospora crassa, and the mushroom Agaricus bisporus, demonstrating that transformation using A. tumefaciens is generally applicable to filamentous fungi.