Generating single metalloprotein crystals in well-defined redox states: electrochemical control combined with infrared imaging of a NiFe hydrogenase crystal.

We describe an approach to generating and verifying well-defined redox states in metalloprotein single crystals by combining electrochemical control with synchrotron infrared microspectroscopic imaging. For NiFe hydrogenase 1 from Escherichia coli we demonstrate fully reversible and uniform electrochemical reduction from the oxidised inactive to the fully reduced state, and temporally resolve steps during this reduction.

Air pollution and emergency department visits for epistaxis.

OBJECTIVES: This study aimed to evaluate the association between outdoor ambient air pollution and emergency department (ED) visits for epistaxis. DESIGN: Cross-sectional study, case-crossover design. SETTING: ED visit data were obtained for Edmonton, Alberta, Canada, for a period of 10 years starting 1 April 1992 and ending March 31st of 2002. The data on ED visits were supplied by Capital Health for the five major acute care hospitals in the Edmonton area. PARTICIPANTS: The analysis was performed for the population as a whole (N = 15 038) and split by sex: males (N = 8587) and females (N = 6451). MAIN OUTCOME MEASURES: We explored associations between ambient concentrations of air pollutants (CO, NO2 , SO2 , O3 , PM10 , PM2.5 ) lagged by 0-4 days and ED visits for epistaxis in Edmonton, Alberta, Canada. RESULTS: Odds ratios (ORs) and their 95% confidence intervals (CI) were reported for an increase in an interquartile range (IQR) of pollutant concentration. We obtained positive and statistically significant results for all patients with epistaxis; exposure to O3 with IQR = 14 ppb, OR = 1.05 (95% CI: 1.00-1.09, lag 0), and for males (age < 25 years), OR = 1.16 (1.03-1.30), lag 4; and to PM10 with IQR = 15 µg/m(3) , OR = 1.02 (1.00-1.05, lag 3). These results were stronger for older (age > 24 years) females. CONCLUSIONS: These findings suggest that there may be an association between air pollutant exposure, specifically ozone and PM10 , and the number of ED visits for epistaxis.

Histone gene arrangement in the sea urchin, Strongylocentrotus purpuratus.

The DNA coding for histones from Strongylocentrotus purpuratus, purified up to 100-fold with the use of Hg+2-CS2-SO4 and actinomycin-CsC1 equilibrium density gradients, has been used to study the clustering of genes coding for different histones and the size of the repeating multigene cluster. When digested with EcoRI restriction endonuclease, the histone DNA is identified in two classes of fragments with molecular weights of 1.15 X 106 and 2.8 X 106, whereas after treatment of the DNA with HindIII restriction endonuclease, histone gene sequences can be identified only in a fragment of 3.95 X 106. Treatment of the DNA with both enzymes simultaneously shows that there is a HindIII site within the smaller EcoRI fragment. Partial digests with HindIII give fragment sizes that appear to be simple multiples of a 3.95 X 106 repeat. Individual histone mRNAs all hybridize to the 3.95 X 106 fragment but only to one or the other EcoRI fragments. The evidence strongly suggests a repeating unit of 3.95 X 106 containing the genes for most, if not all, the histonrs.