Requirement of NifX and other nif proteins for in vitro biosynthesis of the iron-molybdenum cofactor of nitrogenase

The iron-molybdenum cofactor (FeMo-co) of nitrogenase contains molybdenum, iron, sulfur, and homocitrate in a ratio of 1:7:9:1. In vitro synthesis of FeMo-co has been established, and the reaction requires an ATP-regenerating system, dithionite, molybdate, homocitrate, and at least NifB-co (the metabolic product of NifB), NifNE, and dinitrogenase reductase (NifH). The typical in vitro FeMo-co synthesis reaction involves mixing extracts from two different mutant strains of Azotobacter vinelandii defective in the biosynthesis of cofactor or an extract of a mutant strain complemented with the purified missing component. Surprisingly, the in vitro synthesis of FeMo-co with only purified components failed to generate significant FeMo-co, suggesting the requirement for one or more other components. Complementation of these assays with extracts of various mutant strains demonstrated that NifX has a role in synthesis of FeMo-co. In vitro synthesis of FeMo-co with purified components is stimulated approximately threefold by purified NifX. Complementation of these assays with extracts of A. vinelandii DJ42. 48 (DeltanifENX DeltavnfE) results in a 12- to 15-fold stimulation of in vitro FeMo-co synthesis activity. These data also demonstrate that apart from the NifX some other component(s) is required for the cofactor synthesis. The in vitro synthesis of FeMo-co with purified components has allowed the detection, purification, and identification of an additional component(s) required for the synthesis of cofactor.     

Comparison of the carbohydrate and amino acid composition of normal and S-variant alpha-1-antitrypsin.

alpha-1-Antitrypsin has been isolated and purified from the serum of an individual with the Pi S phenotype whose serum contains only 50--60% as much alpha-1-antitrypsin as normal M-type serum. The preparation was homogeneous by the criteria of sodium dodecyl sulfate polyacrylamide gel electrophoresis and sedimentation equilibrium ultracentrigufation. When analyzed in the ultracentrifuge, the S-type alpha-1-antitrypsin exhibited a molecular weight of 47,500 which was essentially the same as that of the M-type (47,300) and the Z-type (47,500) alpha-1-antitrypsin. The S-type alpha-1-antitrypsin contains 15.2% carbohydrate consisting of 16.4 residues/mol of N-acetylglucosamine, 7.8 residues/mol of mannose. 6.7 residues/mol of galactose and 7.1 residues/mol of sialic acid which is essentially the same as the carbohydrate composition of the M-type alpha-1-antitrypsin. In addition, M- and S-type alpha-1-antitrypsin have very similar amino acid compositions.     

Multiregional evaluation of the SimPlate heterotrophic plate count method compared to the standard plate count agar pour plate method in water

A new SimPlate heterotrophic plate count (HPC) method (IDEXX Laboratories, Westbrook, Maine) was compared with the pour plate method at 35 degrees C for 48 h. Six laboratories tested a total of 632 water samples. The SimPlate HPC method was found to be equivalent to the pour plate method by regression analysis (r = 0. 95; y = 0.99X + 0.06).     

Segmental identity and cerebellar granule cell induction in rhombomere 1

Background  

Cerebellar granule cell precursors are specifically generated within the hindbrain segment, rhombomere 1, which is bounded rostrally by the midbrain/hindbrain isthmus and caudally by the boundary of the Hoxa2 expression domain. While graded signals from the isthmus have a demonstrable patterning role within this region, the significance of segmental identity for neuronal specification within rhombomere 1 is unexplored. We examined the response of granule cell precursors to the overexpression of Hoxa2, which normally determines patterns of development specific to the hindbrain. How much does the development of the cerebellum, a midbrain/hindbrain structure, reflect its neuromeric origin as a hindbrain segment?     

Glutathione measurement by high-performance liquid chromatography separation and fluorometric detection of the glutathione-orthophthalaldehyde adduct

Glutathione reacts with orthophthalaldehyde to form a stable, highly fluorescent tricyclic derivative which is easily separated and quantitated by high-performance liquid chromatography. Separation of the glutathione adduct is achieved by isocratic elution over a reverse-phase column with 7.5% methanol/92.5% 0.15 M sodium acetate, pH 7.00. The adduct is detected fluorometrically and quantitated by integration of peak area. Detection of 0.1 to 200 pmol glutathione produces a linear response and the recovery of reduced and oxidized glutathione from rat liver homogenate, bile, and plasma is quantitative. The chemical identity of the adduct was confirmed by mass spectrometry.     

PT-ACRAMTU, A Platinum–Acridine Anticancer Agent, Lengthens and Aggregates, but does not Stiffen or Soften DNA

We used atomic force microscopy (AFM) to study the dose-dependent change in conformational and mechanical properties of DNA treated with PT-ACRAMTU ([PtCl(en)(ACRAMTU-S)](NO₃)₂, (en = ethane-1,2-diamine, ACRAMTU = 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea. PT-ACRAMTU is the parent drug of a family of non-classical platinum-based agents that show potent activity in non-small cell lung cancer in vitro and in vivo. Its acridine moiety intercalates between DNA bases, while the platinum group forms mono-adducts with DNA bases. AFM images show that PT-ACRAMTU causes some DNA looping and aggregation at drug-to-base pair ratio (r _b) of 0.1 and higher. Very significant lengthening of the DNA was observed with increasing doses of PT-ACRAMTU, and reached saturation at an r _b of 0.15. At r _b of 0.1, lengthening was 0.6 nm per drug molecule, which is more than one fully stretched base pair stack can accommodate, indicating that ACRAMTU also disturbs the stacking of neighboring base pair stacks. Analysis of the AFM images based on the worm-like chain (WLC) model showed that PT-ACRAMTU did not change the flexibility of (non-aggregated) DNA, despite the extreme lengthening. The persistence length of untreated DNA and DNA treated with PT-ACRAMTU was in the range of 49–65 nm. Potential consequences of the perturbations caused by this agent for the recognition and processing of the DNA adducts it forms are discussed.     

Efficacy of injections with Disci/Rhus toxicodendron compositum for chronic low back pain--a randomized placebo-controlled trial

Background

The effectiveness of injection therapy for low-back pain is still debatable. We compared the efficacy of local injections of the homeopathic preparation Disci/Rhus toxicodendron compositum (verum) with placebo injections and with no treatment in patients with chronic low back pain.

Methodology/Principal Findings

In a randomized controlled partly double blind multicenter trial patients with chronic low back pain from 9 German outpatient clinics were enrolled and randomly allocated in a 1∶1∶1 ratio to receive subcutaneous injections (verum or placebo) into painful sites on the lower back over 12 treatment sessions within eight weeks, or no treatment (rescue pain medication with paracetamol or NSAIDs). All trial personnel and participants were masked to treatment allocation. The primary outcome measure was the average pain intensity over the last seven days on a visual analogue scale (0–100 mm, 0 = no pain, 100 = worst imaginable pain) after eight weeks. Follow-up was 26 weeks. Primary analysis was by intention to treat. Between August 2007 and June 2008, 150 patients were randomly allocated to three groups (51 verum, 48 placebo and 51 no treatment). The mean baseline-adjusted low back pain intensity at week eight was: verum group 37.0 mm (97.5% CI 25.3;48.8), no treatment group 53.0 (41.8;64.2), and placebo group 41.8 (30.1;53.6). The verum was significantly superior to no treatment (P = 0.001), but not to placebo (P = 0.350). No significant side effects were reported.

Conclusions/Significance

The homeopathic preparation was not superior to placebo. Compared to no treatment injections resulted in significant and clinical relevant chronic back pain relief.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00567736","term_id":"NCT00567736"}}NCT00567736