MSDsite: a database search and retrieval system for the analysis and viewing of bound ligands and active sites

The three-dimensional environments of ligand binding sites have been derived from the parsing and loading of the PDB entries into a relational database. For each bound molecule the biological assembly of the quaternary structure has been used to determine all contact residues and a fast interactive search and retrieval system has been developed. Prosite pattern and short sequence search options are available together with a novel graphical query generator for inter-residue contacts. The database and its query interface are accessible from the Internet through a web server located at: http://www.ebi.ac.uk/msd-srv/msdsite.     

Complement C5b-9 membrane attack complex increases expression of endoplasmic reticulum stress proteins in glomerular epithelial cells

In the passive Heymann nephritis (PHN) model of membranous nephropathy, complement C5b-9 induces glomerular epithelial cell (GEC) injury, proteinuria, and activation of cytosolic phospholipase A(2) (cPLA(2)). This study addresses the role of endoplasmic reticulum (ER) stress proteins (bip, grp94) in GEC injury. GEC that overexpress cPLA(2) (produced by transfection) and "neo" GEC (which expresses cPLA(2) at a lower level) were incubated with complement (40 min), and leakage of constitutively expressed bip and grp94 from ER into cytosol was measured to monitor ER injury. Greater leakage of bip and grp94 occurred in complement-treated GEC that overexpress cPLA(2), as compared with neo, implying that cPLA(2) activation perturbed ER membrane integrity. After chronic incubation (4-24 h), C5b-9 increased bip and grp94 mRNAs and proteins, and the increases were dependent on cPLA(2). Expression of bip-antisense mRNA reduced stimulated bip protein expression and enhanced complement-dependent GEC injury. Glomerular bip and grp94 proteins were up-regulated in proteinuric rats with PHN, as compared with normal control. Pretreatment of rats with tunicamycin or adriamycin, which increase ER stress protein expression, reduced proteinuria in PHN. Thus, C5b-9 injures the ER and enhances ER stress protein expression, in part, via activation of cPLA(2). ER stress protein induction is a novel mechanism of protection from complement attack.     

Oral administration of swine gastric mucin alters levels of serum and urine nitric oxide,and lipid metabolism in mice

Mice were fed with swine gastric mucin in a basal diet for 5 weeks. In 5 week-old mice, a 2% mucin diet significantly decreased nitric oxide levels of serum and liver. Reduction of serum total cholesterol and triglyceride and increase of HDL-cholesterol level were also significant with the mucin diet. In 14 month-old mice, the mucin diet was less effective.     

Seasonal variations of metal contents (Cd, Cu, Fe, Mn and Zn) in seaweed Ulva lactuca from the coast of El Jadida city (Morocco)

The quality of El Jadida Atlantic coastal water was monitored from April 1998 to March 1999 by measuring hydrological parameters (dissolved oxygen, suspended particulate matter, phosphates and nitrites) and using the seaweed Ulva lactuca as a quantitative bio-indicator of cadmium, copper, iron, manganese and zinc contamination. Metal content in seaweeds, collected every month from four stations characterized by the discharge of urban and industrial waste water, showed significant variations depending on the station and sampling period. However, the seaweed of El Jadida exhibited generally lower contents compared to those of similar species from other geographical areas.     

The effect of players' standard and tactical strategy on game demands in men's basketball

The purpose of the present study was to examine the effects of competitive level and team tactic on game demands in men's basketball. Sixteen international-level male basketball players (INPs) and 22 national-level male basketball players (NLPs) were studied during 6 games. Time-motion analysis was performed to track game activities. Game physiological demands were assessed by monitoring heart rate (HR) and blood-lactate concentration. Results showed that INPs sprinted significantly more and performed more high-intensity shuffling than did NLPs (p < 0.05). Game-activity changes and frequency of high-intensity bouts were similar in man-to-man and zone-marking games (1,053 vs. 1,056 and 253 vs. 224, respectively, p > 0.05). Time spent in the maximal (>95% of HRmax) and high-intensity zone (85-95% of HRmax) was greater in the INPs than in the NLPs (17.8 vs. 15.2%, p < 0.01 and 59.1 vs. 54.4%, p < 0.05, respectively). No significant differences in mean HR were evident between man-to-man and zone-marking games (93.3 ± 2.1 vs. 92.8 ± 1.8% of HRmax, p > 0.05). Blood-lactate concentration was higher in the INPs than in the NLPs (6.60 ± 1.22 vs. 5.66 ± 1.19 mmol·L?1 at halftime and 5.65 ± 1.21 vs. 4.43 ± 1.43 mmol·L?1 at full time, p < 0.05). No mean or peak blood-lactate concentration differences resulted between man-to-man and zone-marking games (5.15 ± 1.32 vs. 5.83 ± 1.10 and 5.90 ± 1.25 vs. 6.30 ± 1.27 mmol·L?1, respectively, p > 0.05). These results suggest an effect of competitive level over game demands in men's basketball. No marking strategy effect was evident. Basketball coaches and fitness trainers should develop the ability to repeatedly perform high-intensity activity during the game. Repeated sprinting and high-intensity shuffling ability should be trained to successfully play man-to-man and zone defense, respectively.     

The Small Molecule GMX1778 Is a Potent Inhibitor of NAD+ Biosynthesis: Strategy for Enhanced Therapy in Nicotinic Acid Phosphoribosyltransferase 1-Deficient Tumors

GMX1777 is a prodrug of the small molecule GMX1778, currently in phase I clinical trials for the treatment of cancer. We describe findings indicating that GMX1778 is a potent and specific inhibitor of the NAD⁺ biosynthesis enzyme nicotinamide phosphoribosyltransferase (NAMPT). Cancer cells have a very high rate of NAD⁺ turnover, which makes NAD⁺ modulation an attractive target for anticancer therapy. Selective inhibition by GMX1778 of NAMPT blocks the production of NAD⁺ and results in tumor cell death. Furthermore, GMX1778 is phosphoribosylated by NAMPT, which increases its cellular retention. The cytotoxicity of GMX1778 can be bypassed with exogenous nicotinic acid (NA), which permits NAD⁺ repletion via NA phosphoribosyltransferase 1 (NAPRT1). The cytotoxicity of GMX1778 in cells with NAPRT1 deficiency, however, cannot be rescued by NA. Analyses of NAPRT1 mRNA and protein levels in cell lines and primary tumor tissue indicate that high frequencies of glioblastomas, neuroblastomas, and sarcomas are deficient in NAPRT1 and not susceptible to rescue with NA. As a result, the therapeutic index of GMX1777 can be widended in the treatment animals bearing NAPRT1-deficient tumors by coadministration with NA. This provides the rationale for a novel therapeutic approach for the use of GMX1777 in the treatment of human cancers.The cyanoguanidinopyridine GMX1778 (previously known as CHS828) is the active form of the prodrug GMX1777 and has potent antitumor activity in vitro and in vivo against cell lines derived from several different tumor origins (11). The antitumor activity of GMX1778 has been widely studied since its discovery (1, 11, 19-21, 24), but positive identification of the molecular target and the mechanism of action of GMX1778 has been elusive. Here, we demonstrate that GMX1778 exerts its antitumor activity via its potent and selective antagonism of NAD⁺ biosynthesis. GMX1777 is currently being assessed in phase I clinical trials for treatment of patients with refractory solid tumors.The pyridine nucleotide NAD⁺ plays a major role in the regulation of several essential cellular processes (7, 22, 25, 38). In addition to being a biochemical cofactor for enzymatic redox reactions involved in cellular metabolism, including ATP production, NAD⁺ is important in diverse cellular pathways responsible for calcium homeostasis (17), gene regulation (5), longevity (18), genomic integrity (33), and apoptosis (36). Cancer cells exhibit a significant dependence on NAD⁺ for support of the high levels of ATP production necessary for rapid cell proliferation. They also consume large amounts of this cofactor via reactions that utilize poly(ADP) ribosylation, including DNA repair pathways (10, 37, 39).In eukaryotes, the biosynthesis of NAD⁺ occurs via two biochemical pathways: the de novo pathway, in which NAD⁺ synthesis occurs through the metabolism of l-tryptophan via the kynurenine pathway, and the salvage pathway. The NAD⁺ salvage pathway can use either nicotinamide (niacinamide) (NM) or nicotinic acid (niacin) (NA) (via the Preiss-Handler pathway) as a substrate for NAD⁺ production. Saccharomyces cerevisiae species predominantly use NA as the substrate for NAD⁺ biosynthesis, through the deamidation of NM by the nicotinamidase PNC1 (25). However, mammalian cells do not express a nicotinamidase enzyme and use NM as the preferred substrate for the NAD⁺ salvage pathway. The mammalian NAD⁺ biosynthesis salvage pathway using NM is composed of NA phosphoribosyltransferase (NAMPT), which is the rate-limiting and penultimate enzyme that catalyzes the phosphoribosylation of NM to produce nicotinamide mononucleotide (NMN) (27, 29). NMN is subsequently converted to NAD⁺ by NMN adenyltransferases (NMNAT). The gene encoding NAMPT was originally identified as encoding a cytokine named pre-B-cell colony-enhancing factor (PBEF1) (30). NAMPT was also identified as a proposed circulating adipokine named visfatin (thought to be secreted by fat cells) and was suggested to function as an insulin mimetic; however, this role of NAMPT currently remains controversial (8). In mice, NAMPT has been shown to act as a systemic NAD⁺ biosynthetic enzyme that regulates insulin secretion from β cells (28). The molecular structure of NAMPT from human (15), rat (16) and mouse (35) tissue, containing either NMN or the inhibitor APO866, have been determined by X-ray crystallography. These structures revealed that NAMPT is a dimeric type II phosphoribosyltransferase.Here, we report that the anticancer compound GMX1778 is a specific inhibitor of NAMPT in vivo and in vitro and is itself a substrate for the enzyme. Phosphoribosylated GMX1778 inhibits NAMPT as potently as GMX1778 but is preferentially retained within cells. Finally, we have identified a novel anticancer strategy utilizing NA rescue of GMX1778 cytotoxicity to increase the therapeutic index of GMX1777 activity in tumors that are deficient in NA phosphoribosyltransferase 1 (NAPRT1).     

Shuttle transfer (or retrotransfer) of chromosomal markers mediated by plasmid pULB113

Summary The IncP1 plasmid pULB113 (RP4::miniMu) not only mediates the transfer of chromosomal markers in the classical direction (i.e. from the donor to the recipient cell) but also in the opposite direction (i.e. from the recipient bacterium to the donor). This phenomenon of retrotransfer was observed in homologous matings with Pseudomonas fluorescens, Alcaligenes eutrophus and Salmonella typhimurium. Retrotransconjugants could be discriminated from direct transconjugants by appropriate chromosomal and plasmid markers used to distinguish the mating partners not bearing pULB113. Retrotransfer of chromosomal markers occurred at frequencies equal to, or sometimes greater than, those observed for the direct mobilization, thus allowing the recovery of recipient recessive markers in the donor with linkage values similar to those found in the normal direction. Retrotransfer was also observed in heterospecific matings involving A. eutrophus and pULB113 bearing P. fluorescens: R-primes carrying different selected and unselected markers were recovered in both bacteria. Retrotransfer of shuttle transfer seems to be a specific trait of IncP1 plasmids.     

Induction of a Calcium-dependent Long-term Enhancement of Excitability in the Rat Olfactory Bulb

We have investigated whether a transient increase in extracellularcalcium concentration is able to induce long-term modificationof neuronal excitability in the olfactory bulb. High-calciumartificial cerebrospinal fluid containing picrotoxin (Ca-PTXsolution) was applied locally near the mitral cell layer througha push-pull device for 10 min in anaesthetized rats. Changesin the neuronal excitability were monitored through electrically-evokedfield potentials. Application of the Ca-PTX solution induceda rapid increase in the granule cell response amplitude, whereasmitral/tufted cells response amplitude increased more progressivelyand reached its maximum within a few hours. The increase inmitral/tufted cells response and granule cells response reachedbetween 30 and 100% in experiments which lasted for 4–8h. Pre-application of amino-phosphonovalerate (NMDA receptorblocker) potently reduced both short- and long-term enhancementproduced by the Ca-PTX solution. Neither application of thehigh calcium solution alone nor the picrotoxin solution aloneinduced long-term changes. The results point out the possibleimportance of Ca²⁺ and NMDA receptors in persistent forms ofolfactory bulb plasticity. Relevance of this phenomenon in normalolfactory bulb physiology remains to be examined. Chem. Senses21: 159–168, 1996. ¹Present address: California Institute of Technology, Divisionof Biology 216-76, Pasadena, CA 91125, USA     

Nullomer derived anticancer peptides (NulloPs): Differential lethal effects on normal and cancer cells in vitro

We demonstrate the first use of the nullomer (absent sequences) approach to drug discovery and development. Nullomers are the shortest absent sequences determined in a species, or group of species. By identifying the shortest absent peptide sequences from the NCBI databases, we screened several potential anti-cancer peptides. In order to improve cell penetration and solubility we added short poly arginine tails (5Rs), and initially solubilized the peptides in 1 M trehalose. The results for one of the absent sequences 9R (RRRRRNWMWC), and its scrambled version 9S1R (RRRRRWCMNW) are reported here. We refer to these peptides derived from nullomers as PolyArgNulloPs. A control PolyArgNulloP, 124R (RRRRRWFMHW), was also included. The lethal effects of 9R and 9S1R are mediated by mitochondrial impairment as demonstrated by increased ROS production, ATP depletion, cell growth inhibition, and ultimately cell death. These effects increase over time for cancer cells with a concomitant drop in IC-50 for breast and prostate cancer cells. This is in sharp contrast to the effects in normal cells, which show a decreased sensitivity to the NulloPs over time.