Nanoscale imaging with resonant coherent X rays: extension of multiple-wavelength anomalous diffraction to nonperiodic structures

The methodology of multiple-wavelength anomalous diffraction, widely used for macromolecular structure determination, is extended to the imaging of nonperiodic nanostructures. We demonstrate the solution of the phase problem by a combination of two resonantly recorded coherent scattering patterns at the carbon K edge (285 eV). Our approach merges iterative phase retrieval and x-ray holography approaches, yielding unique and rapid reconstructions. The element, chemical, and magnetic state specificity of our method further renders it widely applicable to a broad range of nanostructures, providing a spatial resolution that is limited, in principle, by wavelength only.

Severe early-onset axonal neuropathy with homozygous and compound heterozygous MFN2 mutations

Objective: Severe early-onset axonal neuropathy (SEOAN) is a heterogeneous phenotype first delineated by Ouvrier et al., characterized by progressive axonal degeneration with gait problems often progressing to wheelchair requirement and later respiratory involvement. Most cases are sporadic single cases. Some have heterozygous mitofusin 2 (MFN2) mutations, many of which are de novo dominant mutations. The aim of this study was to investigate the mode of inheritance in three individuals with severe early-onset axonal neuropathy and homozygous or compound heterozygous MFN2 mutations.

Methods: The clinical and molecular findings in the parents of three individuals with SEOAN with homozygous or compound heterozygous MFN2 mutations were examined.

Results: All parents were asymptomatic or mildly symptomatic with some signs of peripheral neuropathy indicating a minimal phenotype. Two had hearing problems. All parents carried the relevant single base (heterozygous) MFN2 variations.

Conclusion: Severe early-onset axonal neuropathy due to MFN2 mutations can present as an apparently recessively inherited neuropathy but the minimal phenotype in the parents suggests a semi-dominant mechanism.

Anti-inflammatory activities of triterpenoid saponins from Polygala japonica

Bioassay-guided investigation was performed to identify the active constituents from a methanol extract of Polygala japonica, a folk medicinal plant widely used in China to treat inflammatory diseases. The n-BuOH and EtOAc fractions of the P. japonica methanol extract, which show significant anti-inflammatory activity in in vivo test, were further subjected to column chromatography to afford six triterpene glycosides, marked here as saponins 1-6. All compounds were evaluated for their anti-inflammatory activity in the carageenan-induced mouse paw edema test, and saponins 1, 4 and 5 showed significantly anti-inflammatory effects on both phases of carageenan-induced acute paw edema in mice. Saponin 5 was also found to significantly inhibit the production of inflammatory mediators - nitric oxide (NO) in LPS-stimulated RAW264.7 macrophages, with no obvious effects on macrophage viability.

Heavy metal leaching from mine tailings as affected by organic amendments

A column experiment was conducted to investigate Zn, Cd, and Pb leaching from mine tailings as affected by the addition of organic amendments. Composted yard waste, composted cattle manure, and cattle manure aged for one month increased heavy metal leaching from mine tailings when compared to an unamended control. Aged cattle manure and composted cattle manure significantly increased Zn concentration in the leachate. The maximum Zn concentration in leachate from the manure-amended treatments was as high as 3.7 mg/L, whereas Zn concentrations from the control were less than 0.7 mg/L. All organic amendments increased Cd leachate concentrations. The presence of aged cattle manure greatly increased Pb concentrations in the leachate from less than 10 microg/L for the control treatment to higher than 60 microg/L. Lead concentration in leachate was positively correlated with inorganic carbon, total organic carbon, total carbon and bicarbonate. Although organic amendments increased Zn, Cd, and Pb leaching when compared with the control treatment, Zn concentrations were lower than the 5 mg/L secondary drinking water standard, and Pb concentrations were only minimally higher than the 15 microg/L drinking water standard. Cadmium concentrations from manure treatments exceeded the 5 microg/L drinking water standard but only during the first 15 days. Organic amendments may encourage establishment of vegetation in mining areas that may minimize heavy metal contamination through runoff and erosion. However, increased risk due to heavy metal leaching in the presence of organic amendments should be carefully considered.

Stereoselective enzymatic synthesis of chiral alcohols with the use of a carbonyl reductase from Candida magnoliae with anti-Prelog enantioselectivity

In our effort to search for carbonyl reductases with anti-Prelog enantioselectivity, the activity and enantioselectivity of a carbonyl reductase from Candida magnoliae have been examined with various ketones of diverse structures. This carbonyl reductase catalyzed the reduction of a series of ketones, alpha- and beta-ketoesters, to anti-Prelog configurated alcohols in excellent optical purity. The usefulness of this carbonyl reductase has been demonstrated by synthesis of several chiral alcohol intermediates of pharmaceutical importance.

Asymmetric reduction of beta-ketonitriles with a recombinant carbonyl reductase and enzymatic transformation to optically pure beta-hydroxy carboxylic acids

Alpha-ethylation is concomitant with the reduction of aromatic beta-ketonitriles catalyzed by whole-cell biocatalysts. Use of isolated carbonyl reductase has completely eliminated this competing reaction. (R)-beta-Hydroxy nitriles were obtained via a reduction catalyzed by a recombinant carbonyl reductase with excellent optical purity and were further converted to (R)-beta-hydroxy carboxylic acids via a nitrilase-catalyzed hydrolysis. The present study allows ready access to both chiral beta-hydroxy nitriles and beta-hydroxy carboxylic acids of pharmaceutical importance.

Discovery of a mandelonitrile hydrolase from Bradyrhizobium japonicum USDA110 by rational genome mining

A mandelonitrile hydrolase bll6402 from Bradyrhizobium japonicum USDA110 was predicted by rational genome mining, i.e. combining traditional genome mining with functional analysis of the genetic organization of the putative nitrilase gene within the chromosome of microorganisms. This putative gene was cloned and over-expressed in Escherichia coli, and the encoded protein was purified to give a nitrilase with a molecular mass of about 37kDa. The molecular weight of the holoenzyme was about 455kDa, suggesting that nitrilase bll6402 self-aggregated to the active form with native structure being 12 subunits of identical size. This nitrilase was most active toward mandelonitrile with V(max) and K(m) for mandelonitrile being 44.7U/mg and 0.26mM, respectively. The k(cat) and overall catalytic efficiency k(cat)/K(m) were 27.0s(-1) and 1.04x10(5)M(-1)s(-1), indicating that nitrilase bll6402 is very active for the hydrolysis of mandelonitrile to mandelic acid. Nitrilase bll6402 also effectively hydrolyzed several mandelonitrile derivatives.

A molecular modeling study on the enantioselectivity of aryl alkyl ketone reductions by a NADPH-dependent carbonyl reductase

Automated structural analysis of Sporobolomyces salmonicolor carbonyl reductase (SSCR) indicates that the two largest potential receptor sites are in the vicinity of the nicotinamide reductant. The largest receptor site is a scalene triangle with sides of approximately 8 A by 9 A by 13 A, which is narrow in width; one corner is surrounded by hydrophilic residues that can favorably bond with the ketone oxygen. Docking aryl alkyl ketones shows a distinct preference for binding to the largest receptor site, and for conformations that place the carbonyl oxygen of the substrate in the hydrophilic corner of the largest receptor site. Favorable docking conformations for aryl alkyl ketones fall into two low-energy ensembles. These conformational ensembles are distinguished by the positions of the substituents, presenting either the Si- or Re-face of the ketone to the nicotinamide reductant. For the ketones investigated here, there is a correspondence between the major enantiomer of the alcohol obtained from the reduction of the ketone and the conformer found to have the most stable interaction energy with the receptor site in all cases. The receptor site modeling, docking simulations, molecular dynamics, and enzyme-substrate geometry optimizations lead to a model for understanding the enantioselectivity of this NADPH-dependent carbonyl reductase.

Airway hyperresponsiveness induced by repetitive intraperitoneal injection of lipopolysacharide and the involvement of inflammation and nitric oxide in guinea pigs

OBJECTIVE

Airway hyperresponsiveness (AHR) is involved in bronchial asthma and chronic obstructive pulmonary disease (COPD) and produces respiratory symptoms. Lipopolysaccharide (LPS) has been found to be significantly related to the severity of asthma. However, its clinical mechanism still remains controversial. This study investigated the in vivo effect of repetitive intraperitoneal administration of lipopolysaccharide (LPS) on airway hyperresponsiveness (AHR) in guinea pigs and the possible involvement of inflammation, nitric oxide (NO) and nitric oxide synthase (NOS).

METHODS

There were two exposure groups for intraperitoneal LPS injection: (1) LPS was given at a dose of 1 mg x kg(-1), followed by sterile saline (NS) 1 ml x kg(-1) 8 h later every 24 h; (2) LPS was given at a dose of 0.5 mg x kg(-1) two times with an interval of 8 h every 24 h. Each exposure regime was repeated 4 times. Control animals were given NS and 6 naive guinea pigs were used as baseline control. Determinations were made 24 h after each exposure.

RESULTS

Persistent AHR occurred 24 h after the third and fourth exposures to LPS in the first exposure group (at one dose), but occurred earlier after the exposures to LPS in the second exposure group (at divided doses). The numbers of total cells and neutrophils were elevated initially but subsided subsequently in LPS-treated groups. No evidence of morphological changes in the small airways was found 24 h after any of the exposures. The Ca(2+)-dependent and Ca(2+)-independent NOS activities (mainly produced by iNOS) in the BALF, as well as the production of NO, were significantly elevated 24 h after any of third and fourth exposures in LPS-treated groups.

CONCLUSIONS

Our results demonstrate that repetitive intraperitoneal LPS can induce persistent AHR which occurs earlier when the frequency of injection increase, and an elevation of NO production and iNOS activity may be involved in is systemic-LPS-induced AHR.

Enantioselective Enzymatic Reductions of Sterically Bulky Aryl Alkyl Ketones Catalyzed by a NADPH-Dependent Carbonyl Reductase

The enantioselective reductions of aryl alkyl ketones, ArC(O)R, with a diverse number of alkyl groups have been achieved with an isolated carbonyl reductase from Sporobolomyces salmonicolor. Of special interest is the observation that ketones with sterically bulky alkyl groups could be reduced to the corresponding alcohols in excellent optical purity. An unusual alkyl chain-induced enantiopreference reversal was observed but was shown to be consistent with the enzyme-substrate docking calculations.