Repetitive prenatal glucocorticoids increase lung endothelial nitric oxide synthase expression in ovine fetuses delivered at term

Antenatal administration of glucocorticoids has been shown to improve postnatal lung function after preterm birth in the ovine fetus. Mechanisms of steroid-induced lung maturation include increased surfactant production and altered parenchymal lung structure. Whether steroid treatment also affects lung vascular function is unclear. Because nitric oxide contributes to the fall in pulmonary vascular resistance at birth, we hypothesized that the improvement of postnatal lung function of preterm lambs after treatment with prenatal glucocorticoids may be in part caused by an increase in endothelial nitric oxide synthase (eNOS) activity. To determine whether glucocorticoid treatment increases lung eNOS expression, we measured eNOS protein content by Western blot analysis of distal lung homogenates and immunostaining of formalin-fixed lungs from ovine fetuses delivered at preterm and term gestation after prenatal administration of glucocorticoids. Treatment protocols were followed in which ewes were treated with intramuscular betamethasone (0.5 mg/kg) at single or multiple doses at weekly intervals, and fetuses were delivered at 125, 135, or 145 d gestation. All groups were compared with saline-treated controls. Western blot analysis of whole lung homogenates demonstrated a 4-fold increase in eNOS protein content in lambs treated with repetitive doses of glucocorticoids and delivery at term (145 d; p < 0.002). In addition, a small increase in lung eNOS protein content was seen in lambs treated with a single dose of betamethasone at 128 d gestation with delivery at 135 d gestation. In comparison with control animals, there were no differences in lung eNOS content from the remaining lambs treated with glucocorticoids when delivery occurred at preterm ages (125 and 135 d). Immunostaining showed eNOS predominantly in the vascular endothelium in all vessel sizes. Pattern of staining was not altered by treatment with antenatal glucocorticoids. We conclude that maternal treatment with glucocorticoids increases lung eNOS content after multiple doses and delivery at term gestation. We speculate that antenatal glucocorticoids may up-regulate eNOS but that the timing and duration of steroid administration appears to be critical to this response.     

A simple method for fume cupboard performance assessment

The performance of a fume cupboard is determined by a complex interaction of factors which are time consuming and expensive to determine. This paper describes a simple and practical means of ranking, and assessing fume cupboard installations that can help to discharge managerial responsibility for a 'safe' environment. The method also gives an economically viable and technically defensible system for assessing fume cupboard performance as part of upgrading exercises or performance audits. The assessment strategy uses flow visualisation techniques and measurements of inflow air velocity as well as overall condition evaluation to rank performance and identify poor performing cupboards. The method has been used to carry out a condition and performance survey of 199 fume cupboards, both aerodynamic and box-type designs, in an academic institution. The results of this survey are presented which not only highlight performance characteristics but also provide insights into user attitudes and knowledge of fume cupboard operation and performance. It is suggested that surveys such as this could be helpful in training programmes for laboratory workers to enable them to optimise the use of fume cupboards.     

The bedside assessment of splenic enlargement

STUDY OBJECTIVE: To evaluate the clinical assessment of splenic enlargement using specific bedside maneuvers including Traube's space percussion, the splenic percussion sign, Middleton's maneuver, supine palpation, and right lateral decubitus palpation. DESIGN: Quasi-experimental prospective study of cases and controls selected according to the results of abdominal ultrasonographic examinations. SETTING: Selected inpatients of a tertiary care hospital. MAIN RESULTS: Comparing the areas under the receiver operating characteristic curves for each bedside maneuver demonstrated that Traube's space percussion and palpation were significant discriminators (p less than 0.001) of splenic enlargement with respective areas of 0.70 +/- 0.04 and 0.76 +/- 0.04. No one palpation maneuver was superior to another, and right lateral decubitus palpation was not useful when performed after supine palpation. The splenic percussion sign (sensitivity 79%, specificity 46%) was no better than Traube's space percussion (sensitivity 62% and specificity 72%) in assessing splenic enlargement. The palpation maneuvers appeared more sensitive and more specific than Traube's space percussion. Palpation was a significant clinical discriminator when performed on patients who exhibited percussion dullness of Traube's space (area = 0.87 +/- 0.04, p less than 0.0001) but was of little value among those without percussion dullness (area = 0.55 +/- 0.08). Also, palpation was significantly more accurate when performed on lean patients versus obese patients (areas = 0.83 +/- 0.04 versus 0.65 +/- 0.08, p less than 0.05). When a positive bedside examination was defined as positive palpation and positive percussion (concordant-positive), the combined test sensitivity and specificity were 46% and 97% respectively. CONCLUSIONS: The optimal clinical assessment of splenic enlargement includes the percussion of Traube's space. If Traube's space is dull, palpation of the spleen is warranted. This assessment is most accurate in lean patients.     

Enzyme-mediated phosphorylation of polycyclic hydrocarbon metabolites: detection of non-adduct compounds in the 32P-postlabelling assay

32P-Postlabelling analysis is a sensitive method of detecting covalent modification of DNA by chemical carcinogens. We demonstrate that tetrol derivatives of the polycyclic aromatic hydrocarbons (PAHs) benzo[a]pyrene (BP) and chrysene become 32P-labelled in the assay in the absence of nucleic acids. The transfer of 32P from [gamma-32P]ATP to the PAH derivatives requires T4 polynucleotide kinase. Phosphorylated dihydrodiols, phenols, triols and parent hydrocarbons were not detected under standard TLC conditions. Labelling of the non-nucleotide substrates was at least 2000-fold less efficient than labelling of a synthetic BP - DNA adduct. Using 75 microCi[gamma-32P]ATP, the detection limit for BP tetrols was 100-200 pg. Labelling of non-adduct substrates is unlikely to interfere with the analysis of DNA isolated from mammalian tissues, but DNA modified by electrophiles in vitro may, if inadequately purified, give rise to spurious radioactive products.