The reduction of the Rieske iron-sulfur cluster in naphthalene dioxygenase by X-rays

Naphthalene 1,2 dioxygenase (NDO) displays characteristic UV-Vis spectra depending on the oxidation state of the Rieske center. Investigations on crystals of NDO grown for X-ray diffraction experiments showed spectra characteristic of the oxidized form. Crystals reduced in an anaerobic glovebox using sodium-dithionite showed a characteristic reduced spectrum. Spectra of crystals (cooled to 100 K) after being exposed to X-rays for data collection showed spectra corresponding to a reduced Rieske iron center, demonstrating the ability of X-rays to change the oxidation state of the Rieske iron-sulfur cluster in NDO.

Enantiomeric separation of amino alcohols on protein phases using statistical experimental design. A comparative study

Two LC supports often used for giving enantioselective retention were tested and compared in the reversed-phase mode using statistical experimental design. The two supports contain two different proteins, alpha1-acid glycoprotein or cellulase immobilised to silica particles, as the chiral selectors. The two chromatographic columns are commercially available as Chiral-AGP and Chiral-CBH. Twelve closely structurally related amino alcohols were used as the testing solutes. For each column three important mobile phase descriptors, that improve the chiral recognition, were chosen as variables and retention and separation factors were used as responses. All the tested solutes were separated using the two protein based supports. However, the highest enantioselectivities, i.e., separation factors higher than 10 were obtained using the Chiral-CBH column. The solute structure, e.g., distance between the nitrogen atom and the chiral carbon atom, and position as well as type of substituent in the aromatic ring highly influence the enantioselectivity on both columns. For one of the solutes the choice of mobile phase composition could be used to control the retention order of the two enantiomers.

Respiratory burst in human neutrophils

During phagocytosis of microbial intruders, professional phagocytes of our innate immune system increase their oxygen consumption through the activity of an NADPH-oxidase that generates superoxide anion (O(2)(-)) and hydrogen peroxide (H(2)O(2)). These oxygen metabolites give rise to yet other reactive oxygen species that are strongly anti-microbial but which may also cause damage by destructing surrounding tissue and inducing apoptosis in other immune reactive cells. The development of methodology to measure the generation/release of phagocyte respiratory burst products is thus of great importance, and a number of different techniques are currently in use for this purpose. Three of the techniques that we have used, (luminol/isoluminol amplified chemiluminescence, cytochrome C reduction, and PHPA oxidation technique) are described in more detail in this review. We hope to convince the readers that these techniques are valuable tools in basic as well as more clinically oriented research dealing with phagocyte function. The basic principles for luminol/isoluminol-amplified chemiluminescence is used as the starting point for discussing methodological problems related to measurements of oxygen metabolites generated by professional phagocytes.

Identification of CD66a and CD66b as the major galectin-3 receptor candidates in human neutrophils

The mammalian lectin galectin-3 is a potent stimulus of human neutrophils, provided that the receptor(s) for the lectin has been mobilized to the cell surface before activation. We have recently shown that the receptors for galectin-3 are stored in intracellular mobilizable granules. Here we show supportive evidence for this in that DMSO-differentiated (neutrophil-like) HL-60 cells, which lack gelatinase and specific granules, are nonresponsive when exposed to galectin-3. Neutrophil granules were subsequently used for isolation of galectin-3 receptors by affinity chromatography. Proteins eluted from a galectin-3-Sepharose column by lactose were analyzed on SDS-polyacrylamide gels and showed two major bands of 100 and 160 kDa and a minor band of 120 kDa. By immunoblotting, these proteins were shown to correspond to CD66a (160 kDa), CD66b (100 kDa), and lysosome-associated membrane glycoprotein-1 and -2 (Lamp-1 and -2; 120 kDa). The unresponsive HL-60 cells lacked the CD66 Ags but contained the Lamps, implying that neutrophil CD66a and/or CD66b may be the functional galectin-3 receptors. This conclusion was supported by the subcellular localization of the CD66 proteins to the gelatinase and specific granules in resting neutrophils.

Packed-column supercritical fluid chromatography for the purity analysis of clevidipine, a new dihydropyridine drug

In this paper we describe a packed column supercritical fluid chromatography method that can be used for the analysis of a new dihydropyridine substance. The method is based on methanol-modified carbon dioxide as the mobile phase and Hypersil bare silica as column support at a column temperature of 50 degrees C and 150 bar as back pressure. Using an adjusted methanol gradient the most likely by-products can be separated and detected (240 nm) within 13 min. Occasionally the column needed treatment with 4 mM citric acid in the methanol modifier in order to give a narrow peak of an acidic analogue. The present method can detect analogues at the 0.1% (w/w) level. The precision at this level for one of the analogues was 5.9% RSD. This method shows a higher selectivity than a corresponding reversed-phase liquid chromatographic method.

Activation of human neutrophils by mycobacterial phenolic glycolipids

The interaction between mycobacterial phenolic glycolipids (PGLs) and phagocytes was studied. Human neutrophils were allowed to interact with each of four purified mycobacterial PGLs and the neutrophil production of reactive oxygen metabolites was followed kinetically by luminol-/isoluminol-amplified chemiluminescence. The PGLs from Mycobacterium tuberculosis and Mycobacterium kansasii, respectively, were shown to stimulate the production of oxygen metabolites, while PGLs from Mycobacterium marinum and Mycobacterium bovis BCG, respectively, were unable to induce an oxidative response. Periodate treatment of the M. tuberculosis PGL decreased the production of oxygen radicals, showing the importance of the PGL carbohydrate moiety for the interaction. The activation, however, could not be inhibited by rhamnose or fucose, indicating a complex interaction which probably involves more than one saccharide unit. This is in line with the fact that the activating PGLs from M. tuberculosis and M. kansasii contain tri- and tetrasaccharides, respectively, while the nonactivating PGLs from M. marinum and M. bovis BCG each contain a monosaccharide. The complement receptor 3 (CR3) has earlier been shown to be of importance for the phagocyte binding of mycobacteria, but did not appear to be involved in the activation of neutrophils by PGLs. The subcellular localization of the reactive oxygen metabolites formed was related to the way in which the glycolipids were presented to the cells.

In vivo cell recruitment, cytokine release and chemiluminescence response at gold, and thiol functionalized surfaces

Hydroxylated and methylated surfaces were prepared by the self-assembled monolayer technique (SAM) of alkane thiols on gold. The surfaces were used to evaluate the influence of implant surface chemistry on protein deposition and inflammatory cell response. Implants were inserted subcutaneously in the rat for 3 and 24 h. The surface chemical properties influenced the in vitro rat plasma protein adsorption (ellipsometry/antibody) with few exceptions (albumin not found and fibrinogen always found). The number of recruited cells and their distribution (DNA from implant versus from exudate) was influenced by the different chemistries at 24 h, but not at 3 h. HIS48+, ED1+, ED2+ and small numbers of CD5+ cells were present in the exudate at both time periods (flow cytometry). The cellular oxidative metabolism was low, although cells on -OH surfaces responded with the highest phorbol ester-stimulated chemiluminescence (CL)/DNA. The levels of cytokines IL-1alpha, IL-1beta and TNFalpha (ELISA) were not influenced by material surface chemistry. Sham operated sites had a higher cytokine concentration/DNA compared with exudates from an implant milieu. The results of this study show that surface chemical functionalization modifies specific events in the inflammatory response around implants in soft tissues.

Cloning of mouse mitochondrial thymidine kinase 2 cDNA

Phosphorylation of anti-viral nucleoside analogs by mitochondrial thymidine kinase 2 (TK2) has been implicated as a mechanism for the mitochondrial toxicity caused by several of these compounds. We have cloned the cDNA of mouse TK2 and shown that the enzyme is targeted to the mitochondria when expressed in fusion with the green fluorescent protein. This is the first report on the cloning of a mitochondrial TK2 and will contribute to elucidate the role of TK2 in the pharmacological activation of nucleoside analogs.

Enantiometric separation of verapamil and norverapamil using Chiral-AGP as the stationary phase

Simultaneous enantiomeric separation of verapamil and its main metabolite norverapamil was achieved using Chiral-AGP as the stationary phase. The optimized chromatographic system was obtained using statistical experimental design with partial least squares as regression method. The three variables studied were buffer pH, content of acetonitrile and column temperature. A high buffer pH favors enantioselectivity as well as the selectivity between (S)-verapamil and (R)-norverapamil. The concentration of the organic modifier in the mobile phase was a compromise as a high content of acetonitrile decreased enantioselectivity but increased the selectivity mentioned above. Increased column temperature increased the separation between (S)-verapamil and (R)-norverapamil with only a slight decrease in enantioresolution.

Combined effect of epinephrine and exercise on calpain/calpastatin and cathepsin B and L activity in porcine longissimus muscle

The objective of the study was to improve the understanding of the relationship between the effect of epinephrine plus exercise and meat tenderness. The calpain, calpastatin, and cathepsin B + L activities and postmortem proteolysis in porcine longissimus muscle were studied. The muscle glycogen stores were depleted in five pigs by s.c. injection of epinephrine (.3 mg/kg) at 15 h antemortem and exercise on a treadmill (5 min, 3.8 km/h) immediately before slaughter. Antemortem injection of epinephrine and treadmill exercise resulted in higher ultimate pH (6.32 vs 5.66 in control) and decreased (P < .05) thaw loss, cooking loss, and shear force values. The muscle energy depletion treatment increased (P < .05) the muscle mu-calpain activity measured 42 min postmortem, and at 24 h mu-calpain activity was still approximately 50% greater in the high ultimate pH group. Also, as the ratio of mu-calpain to calpastatin increased (P < .01), the overall proteolytic potential of the calpain system were greater. These observations suggest that the muscle energy level may influence the activity of the calpain system in the living animal. The high ultimate pH group showed lower (P < .001) cathepsin B + L activity in the myofibrillar and the soluble fractions after 8 d of storage, suggesting that the increased ultimate pH increased the stability of the lysosomal membrane and thereby reduced the release of cathepsins from the lysosomes during storage. The SDS-PAGE showed increased (P < .001) degradation of a 39-kDa band in the epinephrine and exercise-treated samples. Degradation products at 30, 31, and 32 kDa were labeled by troponin-T antibody in western blot. An appearing 24-kDa band was identified as a troponin-I degradation product in western blot. The proteolytic degradation pattern of myofibrillar proteins during storage differed in control and treated samples, supporting the hypothesis that calpain-mediated proteolysis was affected after treatment, resulting in meat with high ultimate pH.

Phosphorylation of deoxycytidine analog monophosphates by UMP-CMP kinase: molecular characterization of the human enzyme

Phosphorylation of deoxycytidine analogs by cellular enzymes is a prerequisite for the activity of these compounds. We have investigated the kinetic parameters for the phosphorylation of 1-beta-D-arabinofuranosylcytosine (araC) and 2', 2'-difluorodeoxycytidine (dFdC) to their diphosphate forms catalyzed by human UMP-CMP kinase. We cloned the cDNA of this enzyme to enable characterization of the recombinant protein, determine its expression in different tissues, and determine the chromosome location of the gene. We showed that the recombinant UMP-CMP kinase phosphorylated CMP, dCMP, and UMP with highest efficiency and dUMP, AMP, and dAMP with lower efficiency. The monophosphates of araC and dFdC were shown to be phosphorylated with similar efficiency as dCMP and CMP. We further showed, in a combined enzymatic assay, that human deoxycytidine kinase and UMP-CMP kinase together phosphorylated araC, dFdC, and 2',3'-dideoxycytidine to their diphosphate forms. Northern blot analysis showed that the UMP-CMP kinase mRNA was ubiquitously present in human tissues as a 3.9-kb transcript with highest levels in pancreas, skeletal muscle, and liver. The human UMP-CMP kinase gene was localized to chromosome 1p34.1-1p33 by radiation hybrid analysis. We further expressed the UMP-CMP kinase as a fusion protein to the green fluorescent protein in Chinese hamster ovary cells, and showed that the fusion protein was located in the cytosol and nucleus.

5'-Phosphoramidates and 5'-diphosphates of 2'-O-allyl-beta-D-arabinofuranosyluracil, -cytosine, and -adenine: inhibition of ribonucleotide reductase

Continuing our studies on ribonucleotide reductase (RNR) mechanism-based inhibitors, we have now prepared the diphosphates (DP) of 2'-O-allyl-1-beta-D-arabinofuranosyl-uracil and -cytosine and 2'-O-allyl-9-beta-D-arabinofuranosyl-adenine and evaluated their inhibitory activity against recombinant murine RNR. 2'-O-Allyl-araUDP proved to be inhibitory to RNR at an IC(50) of 100 microM, whereas 2'-O-allyl-araCDP was only marginally active (IC(50) 1 mM) and 2'-O-allyl-araADP was completely inactive. The susceptibility of the parent nucleosides to phosphorylation by thymidine kinase and 2'-deoxycytidine kinase was also investigated, and all nucleosides proved to be poor substrates for the above-cited kinases. Moreover, prodrugs of 2'-O-allyl-araU and -araC monophosphates, namely 2'-O-allyl-5'-(phenylethoxy-L-alanyl phosphate)-araU and -araC, were prepared and tested against tumor cell proliferation but proved to be inactive. A molecular modeling study has been conducted in order to explain our results. The data confirm that for both the natural and analogue nucleoside diphosphates, the principal determinant interaction with the active site of RNR is with the diphosphate group, which forms strong hydrogen bonds with Glu623, Thr624, Ser625, and Thr209. Our findings indicate that the poor phosphorylation may represent an explanation for the lack of marked in vitro cytostatic activity of the test compounds.

Cloning and characterization of the multisubstrate deoxyribonucleoside kinase of Drosophila melanogaster

A Drosophila melanogaster deoxyribonucleoside kinase (Dm-dNK) was reported to phosphorylate all four natural deoxyribonucleosides as well as several nucleoside analogs (Munch-Petersen, B., Piskur, J., and Sondergaard, L. (1998) J. Biol. Chem. 273, 3926-3931). The broad substrate specificity of this enzyme together with a high catalytic rate makes it unique among the nucleoside kinases. We have in the present study cloned the Dm-dNK cDNA, expressed the 29-kDa protein in Escherichia coli, and characterized the recombinant enzyme for the phosphorylation of nucleosides and clinically important nucleoside analogs. The recombinant enzyme preferentially phosphorylated the pyrimidine nucleosides dThd, dCyd, and dUrd, but phosphorylation of the purine nucleosides dAdo and dGuo was also efficiently catalyzed. Dm-dNK is closely related to human and herpes simplex virus deoxyribonucleoside kinases. The highest level of sequence similarity was noted with human mitochondrial thymidine kinase 2, and these enzymes also share many substrates. The cDNA cloning and characterization of Dm-dNK will be the basis for studies on the use of this multisubstrate nucleoside kinase as a suicide gene in combined gene/chemotherapy of cancer.

Use of novel bone biopsy system to study molecular effects of growth hormone in human bone--a pilot study

In this study, we have examined whether a novel bone biopsy system combined with reverse transcription-polymerase chain reaction (RT-PCR) or differential display PCR (ddPCR) can be used to detect specific mRNAs induced by growth hormone (GH) in human bone. In a 58-year-old man with complete GH deficiency as a result of empty sella, bone biopsies were taken before, and 5 and 24 h after administration of 24 recombinant human GH. Insulin-like growth factor binding protein-3 (IGFBP-3) mRNA levels in this patient, measured in a semiquantitative RT-PCR assay, increased about 40% 24 h after GH administration. This increase was not seen in a healthy control who did not receive GH, suggesting that the increase was an effect of GH rather than of the biopsy itself. Several differentially expressed mRNAs were detected by ddPCR. Thus, this pilot study suggests that our novel bone biopsy system may be suitable for in vivo studies of the molecular effects of substances with essential functions in human bone.

Wheat germ agglutinin induces NADPH-oxidase activity in human neutrophils by interaction with mobilizable receptors

Wheat germ agglutinin (WGA), a lectin with specificity for N-acetylglucosamine and sialic acid, was investigated with respect to its ability to activate the NADPH-oxidase of in vivo-exudated neutrophils (obtained from a skin chamber), and the activity was compared to that of peripheral blood neutrophils. The exudate cells responded to WGA, by both releasing reactive oxygen species into the extracellular milieu and producing oxygen metabolites intracellularly. The peripheral blood cells were unresponsive. To mimic the in vivo-exuded neutrophils with regards to receptor exposure, peripheral blood neutrophils were induced to mobilize their granules and vesicles to varying degrees (in vitro priming), prior to challenge with WGA. The oxidative response to WGA increased with increasing levels of granule mobilization, and the receptor(s) could be shown to reside in the secretory vesicles and/or the gelatinase granules in resting neutrophils. Several WGA-binding glycoproteins were detected in subcellular fractions containing these organelles. The extra- and intracellular NADPH-oxidase responses showed differences in sialic acid dependency, indicating that these two responses are mediated by different receptor structures.

Experiments on long wavelength (1550 nm) "plug and play" quantum cryptography systems

An interferometric quantum cryptographic system at 1550nm wavelength using gated InGaAs Avalanche Photo Diodes as single-photon receivers is demonstrated for a transmission distance up to 40 km.

The phagocyte chemiluminescence paradox: luminol can act as an inhibitor of neutrophil NADPH-oxidase activity

The chemiluminescence system amplified by luminol or isoluminol is a sensitive and widely used method for determination of respiratory burst products generated by the NADPH-oxidase in phagocytes. The present study shows that luminol, but not isoluminol, can inhibit the release of oxygen metabolites generated by human neutrophil NADPH-oxidase. The difference in structure between luminol and isoluminol (rendering luminol more lipophilic than isoluminol, and thereby membrane-permeable), is suggested to determine indirectly whether or not the molecule is inhibitory. Luminol was shown to have an increased inhibitory effect after preincubation of neutrophils on a surface of aggregated IgG, suggesting that the cells can be transferred from a 'luminol-insensitive' to a 'luminol-sensitive' state. Since luminol had no inhibitory effect in a cell-free NADPH-oxidase system, it is likely that it interferes with the signal transduction pathway, leading to assembly and/or activation of the oxidase. As a consequence of the present results, showing that luminol but not isoluminol can inhibit NADPH-oxidase activity, we suggest that isoluminol is used in future studies of superoxide anion release from phagocytes.

A new bone dust packer for use in neurosurgery

A new tool for the packing of bone dust has been developed. The instrument compresses a mixture of bone dust and saline into suitable cylindrical plugs, fitting neatly into craniotomy burrholes. The skullbone at the craniotomy area will heal neatly also assuring the best healing possibilities for the overlying skin. The cosmetic results are excellent as no skin dents or cavities will be formed over the burrholes.

Identification of a novel human adenylate kinase. cDNA cloning, expression analysis, chromosome localization and characterization of the recombinant protein

Adenylate kinases have an important role in the synthesis of adenine nucleotides that are required for cellular metabolism. We report the cDNA cloning of a novel 22-kDa human enzyme that is sequence related to the human adenylate kinases and to UMP/CMP kinase of several species. The enzyme was expressed in Escherichia coli and shown to catalyse phosphorylation of AMP and dAMP with ATP as phosphate donor. When GTP was used as phosphate donor, the enzyme phosphorylated AMP, CMP, and to a small extent dCMP. Expression as a fusion protein with the green fluorescent protein showed that the enzyme is located in the cytosol. Northern blot analysis with mRNA from eight different human tissues demonstrated that the enzyme was expressed exclusively in brain, with two mRNA isoforms of 2.4 and 4.0 kb. The gene that encoded the enzyme was localized to chromosome 1p31. Based on the substrate specificity and the sequence similarity with the previously identified human adenylate kinases, we have named this novel enzyme adenylate kinase 5.

Synthesis, cytostatic activity and inhibition of ribonucleotide reductase by 5'-phosphoramidates and 5'-diphosphates, of 2'-O-allyl-arabinofuranosyl nucleosides

The diphosphates of a series of 2'-O-allyl-1-beta-D-arabinofuranosyl derivatives, previously obtained by us, have been prepared and tested for their inhibitory activity in an in vitro assay using R1 and R2 subunits of the purified recombinant mouse ribonucleotide reductase (RNR). 2'-O-Allyl-araU diphosphate proved to be inhibitory, with an IC50 of 100 microM. The 5'-phosphoramidate pronucleotide of 2'-O-allyl-araU was also prepared and tested for inhibition of tumor cell proliferation.

Chemical transformations in individual ultrasmall biomimetic containers

Individual phospholipid vesicles, 1 to 5 micrometers in diameter, containing a single reagent or a complete reaction system, were immobilized with an infrared laser optical trap or by adhesion to modified borosilicate glass surfaces. Chemical transformations were initiated either by electroporation or by electrofusion, in each case through application of a short (10-microsecond), intense (20 to 50 kilovolts per centimeter) electric pulse delivered across ultramicroelectrodes. Product formation was monitored by far-field laser fluorescence microscopy. The ultrasmall characteristic of this reaction volume led to rapid diffusional mixing that permits the study of fast chemical kinetics. This technique is also well suited for the study of reaction dynamics of biological molecules within lipid-enclosed nanoenvironments that mimic cell membranes.