Interaction of uranium with a filamentous, heterocystous, nitrogen-fixing cyanobacterium, Anabaena torulosa.

The filamentous, heterocystous, diazotrophic cyanobacterium, Anabaena torulosa was found to bind uranium from aqueous solutions containing 100 µM uranyl carbonate at pH 7.8. The uranyl sequestration kinetics exhibited (a) an initial rapid phase, binding 48% uranium within 30 min resulting in a loading of 56 mg U g(-1) of dry wt, followed by (b) a slower phase, binding 65% uranium with resultant loading of 77.35 mg U g(-1) in 24h. Energy Dispersive X-ray fluorescence spectroscopy of uranium loaded biomass revealed all components of UL X-rays (UL(l), UL(α), UL(ß1) and UL(ß2)). Heat killed cells or extracellular polysaccharides derived from live cells exhibited limited uranyl binding (~26%) highlighting the importance of cell viability for optimum uranyl binding. The present study revealed the involvement of acid soluble polyphosphates in uranium accumulation by this brackish water cyanobacterium.

Uranium sequestration by a marine cyanobacterium, Synechococcus elongatus strain BDU/75042.

A marine, unicellular cyanobacterium, Synechococcus elongatus strain BDU/75042 was found to sequester uranium from aqueous systems at pH 7.8. The organism could remove 72% (53.5 mg U g(-1) dry weight) of uranium from test solutions containing 100 microM uranyl carbonate within 1h. The equilibrium data fitted well in the Langmuir isotherm thus suggesting a monolayer adsorption of uranium on the cyanobacterial biomass and predicted the maximum adsorption capacity of 124 mg U g(-1) dry weight. Light and scanning electron microscopy coupled with energy dispersive X-ray fluorescence (EDXRF) spectroscopy confirmed the uranyl adsorption by this organism. Most of the bound uranium was found to be associated with the extracellular polysaccharides (EPS) suggesting its interaction with the surface active ligands. Fourier transform infrared (FT-IR) spectroscopy suggested the amide groups and the deprotonated carboxyl groups on the cyanobacterial cell surface were likely to be involved in uranyl adsorption. The cell bound uranium could be released by washing with ethylene diamine tetraacetic acid (EDTA) or 0.1N HCl. The X-ray diffraction (XRD) analyses revealed the identity of uranium deposits associated with the cell biomass as uranyl carbonate hydrate. The study revealed the potential of this cyanobacterium for harvesting uranium from natural aquatic environments.

LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development.

In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.

Time dependent influence of diazepam on the pharmacokinetics of ibuprofen in man.

Circadian variation in the disease activity of rheumatoid arthritis has been established. Several nonsteroidal anti-inflammatory drugs have been studied for their chronokinetic behaviour. Time dependent influence of diazepam on the pharmacokinetics of diclofenac and naproxen has been reported. We report the time dependent influence of diazepam on the pharmacokinetics of ibuprofen in healthy subjects. Either ibuprofen or ibuprofen with diazepam was administered at 10.00 or 22.00 hours to eight healthy volunteers in a randomized crossover study. Serum ibuprofen levels were estimated by high performance liquid chromatography. There was a significant (p < 0.05) increase in mean elimination half life (2.39 +/- 0.42 to 3.59 +/- 0.35 h) following ibuprofen and diazepam administration compared to ibuprofen alone administered at 22.00 hours. The mean clearance of ibuprofen was therefore lowered from 62.7 +/- 8.9 to 41.7 +/- 2.6 ml/h/kg under the influence of diazepam during the night. Such a time dependent influence of diazepam on the pharmacokinetics of ibuprofen may be due to circadian variation in the pattern of protein production in the liver and/or competitive protein binding of the two drugs during the dark period.

Identification and characterization of a novel human matrix metalloproteinase with unique structural characteristics, chromosomal location, and tissue distribution.

We have cloned a novel member of the matrix metalloproteinase (MMP) family of proteins from a human liver cDNA library. The isolated cDNA contains an open reading frame coding for a polypeptide of 508 amino acids, which has been tentatively called MMP-19. This protein exhibits the domain structure characteristic of previously described MMPs, including a signal sequence, a prodomain with the cysteine residue essential for maintaining the latency of these enzymes, an activation locus with the zinc-binding site, and a COOH-terminal fragment with sequence similarity to hemopexin. However, it lacks a series of structural features distinctive of the diverse MMP subclasses, including the Asp, Tyr, and Gly residues located close to the zinc-binding site in collagenases, the fibronectin-like domain of gelatinases, the transmembrane domain of membrane-type (MT) MMPs, and the furin-activation sequence common to stromelysin-3 and MT-MMPs. In addition, the 9-residue insertion rich in hydrophobic amino acids present at the hinge region in stromelysins is replaced in MMP-19 by a longer insertion very rich in acidic residues. On the basis of these structural characteristics, we propose that MMP-19 does not belong to any of the previously defined MMP-subclasses and may represent the first member of a new MMP subfamily. Chromosomal location of the MMP-19 gene revealed that it maps to chromosome 12q14, which is also a unique location for any MMPs mapped to date. The cDNA encoding a full-length MMP-19 was expressed in Escherichia coli, and after purification and refolding, the recombinant protein was able to degrade synthetic substrates for MMPs. MMP-19 proteolytic activity was abolished by TIMP-2 and EDTA, thus providing additional evidence that the isolated cDNA codes for an authentic MMP. Northern blot analysis of polyadenylated RNAs isolated from a variety of human tissues revealed that MMP-19 is mainly expressed in placenta, lung, pancreas, ovary, spleen, and intestine, suggesting that it may play a specialized role in these tissues.

Plant and algal interference in bacterial beta-D-galactosidase and beta-D-glucuronidase assays.

Several commonly occurring freshwater and marine plants and algae were screened for beta-D-galactosidase and beta-D-glucuronidase activities by using a 60-min enzyme assay based on the hydrolysis by these enzymes of 4-methylumbelliferyl-beta-D-galactoside and 4-methylumbelliferyl- beta-glucuronide, respectively. All freshwater plant extracts tested showed beta-D-galactosidase activity several at relatively high levels, and a number also showed beta-D-glucuronidase activity. A number of the macroalgae showed no activity of either enzyme, but those showing beta-D-galactosidase activity also showed beta-D-glucuronidase activity. The majority of microalgae showed some beta-D-galactosidase activity, but few showed beta-D-glucuronidase activity. Further studies, using the commercial Colilert test and the marine water formulation of Colilert, revealed that 2 of 11 of the microalgal species and several of the plant extracts tested caused positive reactions. It was concluded that several plant extracts and algae could significantly interfere with the detection of coliform bacteria and Escherichia coli with the use of rapid assays, on the basis of their production of beta-D-galactosidase and beta-D-glucuronidase, respectively. The significance of the plant and algal interferences in tests such as Colilert is dependent on the levels of enzymes released under natural conditions, the dilution which they may undergo, and the numbers of algal cells present. This also applies to interferences in rapid enzyme assays.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning of the cDNA encoding human tissue inhibitor of metalloproteinases-3 (TIMP-3) and mapping of the TIMP3 gene to chromosome 22.

The tissue inhibitors of metalloproteinases (TIMPs) are natural inhibitors of the matrix metalloproteinases, a group of zinc-binding endopeptidases involved in the degradation of the extracellular matrix. We have isolated overlapping cDNAs encoding a novel human TIMP, TIMP-3. The cDNAs contain a 591-bp-long open reading frame encoding 9 amino acid residues of the signal peptide and 188 residues of the mature TIMP-3 polypeptide. Both the nucleotide sequence and the conceptual translation product of the human TIMP3 cDNA have a high degree of similarity to ChIMP-3, a recently cloned metalloproteinase inhibitor in the chicken, and to the TIMP1 and TIMP2 gene products, including 12 conserved cysteinyl residues at the same relative positions. The TIMP3 gene is expressed in many tissues, with highest expression in the placenta. Upon hybridization with a panel of human-hamster somatic cell hybrid DNAs, the TIMP3 gene segregated with clones containing chromosome 22. Using in situ hybridization to human metaphase chromosomes, we have assigned the locus for the TIMP3 gene to the q12.1-q13.2 region of human chromosome 22.

Mono ferrous acid citrate (FeC6O7H2O) as an iron fortificant.

1. Iron absorption from ferrous citrate (monoferrous acid citrate, FeC6H6O7H2O) was studied in normal healthy male and female volunteers using ferrous citrate labelled with radioactive Fe and whole-body counting. Ferrous citrate was either given alone or with a rice-based meal. 2. Fe absorption from ferrous citrate was satisfactory and was comparable to that from ferrous sulphate. 3. Fortification of crude cooking salt with ferrous citrate was not satisfactory due to colour development on storage. Ferrous citrate can, however, serve as an effective Fe fortificant with sugar or wheat flour.