Amiloride does not alter NaCl avoidance in Fischer-344 rats

Fischer-344 (F-344) rats differ from other common rat strains in that they fail to show any preference for NaCl at any concentration in two- bottle preference tests. Because 100 microM amiloride partially blocks the NaCl-evoked chorda tympani (CT) response in electrophysiological studies, we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without 100 microM amiloride solution as the solvent. A third group was tested with unadulterated NaCl solutions following CT transection. Amiloride had no significant effect on the NaCl preference-aversion function, whereas CT transection significantly reduced NaCl avoidance. These results suggest that the amiloride-sensitive component of the NaCl response is not necessary for F-344 rats to display avoidance of NaCl, but the entire CT input is.      

Characterization and purification of helveticin J and evidence for a chromosomally determined bacteriocin produced by Lactobacillus helveticus 481.

Lactobacillus helveticus 481 produced an antimicrobial agent active against five closely related species. The sensitive indicators included L. helveticus 1846 and 1244, L. bulgaricus 1373 and 1489, and L. lactis 970. The antimicrobial compound was active at neutral pH under aerobic or anaerobic conditions, was sensitive to proteolytic enzymes and heat (30 min at 100 degrees C), and demonstrated a bactericidal mode of action against sensitive indicators. These data confirmed that antimicrobial activity of L. helveticus 481 was mediated by a bacteriocin, designated helveticin J. Production of helveticin J was maximized in an anaerobic fermentor held at a constant pH of 5.5. Ultrafiltration experiments on culture supernatants containing the bacteriocin revealed that helveticin J was present as an aggregate with a molecular weight in excess of 300,000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of helveticin J purified through Sephadex chromatography resolved a 37,000-dalton protein band with bacteriocin activity. L. helveticus 481 was shown to harbor a single 8-megadalton plasmid (pMJ1008). Isolates cured of pMJ1008 were phenotypically identical to plasmid-bearing cells in fermentation patterns, helveticin J activity, and immunity spectra. The data provided evidence for a chromosomal location of helveticin J and host immunity determinants.     

Bacteria as workers in the living factory: metal-accumulating bacteria and their potential for materials science

Metal micro-/nano-particles with suitable chemical modification can be organized into new ceramic-metal (cermet) or organic-metal (orgmet) composites or structured materials. These materials are attracting significant attention because of their unique structures and highly optimized properties. However, the synthesis of composite materials with inhomogeneities on the nanometer or sub-micrometer scale is a continuing challenge in materials science. Many industrial physical and chemical surface-coating processes using conventional techniques are both energy and cost inefficient and require sophisticated instrumentation. In the future, biology might offer a superior option.     

Cloning, expression, and nucleotide sequence of the Lactobacillus helveticus 481 gene encoding the bacteriocin helveticin J.

Lactobacillus helveticus 481 produces a 37-kDa bacteriocin called helveticin J. Libraries of chromosomal DNA from L. helveticus were prepared in lambda gt11 and probed for phage-producing fusion proteins that could react with polyclonal helveticin J antibody. Two recombinant phage, HJ1 and HJ4, containing homologous inserts of 350 and 600 bp, respectively, produced proteins that reacted with antibody. These two phage clones specifically hybridized to L. helveticus 481 total genomic DNA but not to DNA from strains that did not produce helveticin J or strains producing unrelated bacteriocins. HJ1 and HJ4 lysogens produced beta-galactosidase fusion proteins that shared similar epitopes with each other and helveticin J. The intact helveticin J gene (hlv) was isolated by screening a library of L. helveticus chromosomal DNA in lambda EMBL3 with the insert DNA from phage HJ4 as a probe. The DNA sequence of a contiguous 3,364-bp region was determined. Two complete open reading frames (ORF), designated ORF2 and ORF3, were identified within the sequenced fragment. The 3' end of another open reading frame, ORF1, was located upstream of ORF2. A noncoding region and a putative promoter were located between ORF1 and ORF2. ORF2 could encode an 11,808-Da protein. The L. helveticus DNA inserts of the HJ1 and HJ4 clones reside within ORF3, which begins 30 bp downstream from the termination codon of ORF2. ORF3 could encode a 37,511-Da protein. Downstream from ORF3, the 5' end of another ORF (ORF4) was found. A Bg/II fragment containing ORF2 and ORF3 was cloned into pGK12, and the recombinant plasmid, pTRK135, was transformed into Lactobacillus acidophilus via electroporation. Transformants carrying pTRK135 produced a bacteriocin that was heat labile and exhibited an acitivity spectrum that was the same as that of helveticin J.     

Bone formation rather than inflammation reflects Ankylosing Spondylitis activity on PET-CT: a pilot study

Introduction

Positron Emission Tomography - Computer Tomography (PET-CT) is an interesting imaging technique to visualize Ankylosing Spondylitis (AS) activity using specific PET tracers. Previous studies have shown that the PET tracers [¹⁸F]FDG and [¹¹C](R)PK11195 can target inflammation (synovitis) in rheumatoid arthritis (RA) and may therefore be useful in AS. Another interesting tracer for AS is [¹⁸F]Fluoride, which targets bone formation. In a pilot setting, the potential of PET-CT in imaging AS activity was tested using different tracers, with Magnetic Resonance Imaging (MRI) and conventional radiographs as reference.

Methods

In a stepwise approach different PET tracers were investigated. First, whole body [¹⁸F]FDG and [¹¹C](R)PK11195 PET-CT scans were obtained of ten AS patients fulfilling the modified New York criteria. According to the BASDAI five of these patients had low and five had high disease activity. Secondly, an extra PET-CT scan using [¹⁸F]Fluoride was made of two additional AS patients with high disease activity. MRI scans of the total spine and sacroiliac joints were performed, and conventional radiographs of the total spine and sacroiliac joints were available for all patients. Scans and radiographs were visually scored by two observers blinded for clinical data.

Results

No increased [¹⁸F]FDG and [¹¹C](R)PK11195 uptake was noticed on PET-CT scans of the first 10 patients. In contrast, MRI demonstrated a total of five bone edema lesions in three out of 10 patients. In the two additional AS patients scanned with [¹⁸F]Fluoride PET-CT, [¹⁸F]Fluoride depicted 17 regions with increased uptake in both vertebral column and sacroiliac joints. In contrast, [¹⁸F]FDG depicted only three lesions, with an uptake of five times lower compared to [¹⁸F]Fluoride, and again no [¹¹C](R)PK11195 positive lesions were found. In these two patients, MRI detected nine lesions and six out of nine matched with the anatomical position of [¹⁸F]Fluoride uptake. Conventional radiographs showed structural bony changes in 11 out of 17 [¹⁸F]Fluoride PET positive lesions.

Conclusions

Our PET-CT data suggest that AS activity is reflected by bone activity (formation) rather than inflammation. The results also show the potential value of PET-CT for imaging AS activity using the bone tracer [¹⁸F]Fluoride. In contrast to active RA, inflammation tracers [¹⁸F]FDG and [¹¹C](R)PK11195 appeared to be less useful for AS imaging.