Relation between mechanical foam-breaking difficulty and the foaming characteristics of solutions

Using a small foaming apparatus, liquid foaming characteristics such as liquid holdup in foamate flow (φ_t), rate of liquid drainage from foam (ν), foam velocity (u_f) and foam size (d_f) were examined for various liquids. A parameter φ_f, incorporating φ_t, ν and u_f, was obtained. The relationship among φ_f, d_f and the liquid holdup in foam, φ_b, in the actual gas-bubbling systems under foam control was expressed in the form of φ_b ∞ φ_fd_f^1.83, regardless of the type of foaming liquid or its concentration. This relationship was useful for the prediction of φ_b as related to mechanical foam-breaking difficulty.     

Benzo[d]isothiazole 1,1-dioxide derivatives as dual functional inhibitors of 5-lipoxygenase and microsomal prostaglandin E2 synthase-1

A series of 6-nitro-3-(m-tolylamino) benzo[d]isothiazole 1,1-dioxide analogues were synthesized and evaluated for their inhibition activity against 5-lipoxygenase (5-LOX) and microsomal prostaglandin E₂ synthase (mPGES-1). These compounds can inhibit both enzymes with IC₅₀ values ranging from 0.15 to 23.6 μM. One of the most potential compounds, 3g, inhibits 5-LOX and mPGES-1 with IC₅₀ values of 0.6 μM, 2.1 μM, respectively.     

(φ,ψ)₂ motifs: a purely conformation-based fine-grained enumeration of protein parts at the two-residue level

A deep understanding of protein structure benefits from the use of a variety of classification strategies that enhance our ability to effectively describe local patterns of conformation. Here, we use a clustering algorithm to analyze 76,533 all-trans segments from protein structures solved at 1.2 Å resolution or better to create a purely φ,ψ-based comprehensive empirical categorization of common conformations adopted by two adjacent φ,ψ pairs (i.e., (φ,ψ)₂ motifs). The clustering algorithm works in an origin-shifted four-dimensional space based on the two φ,ψ pairs to yield a parameter-dependent list of (φ,ψ)₂ motifs, in order of their prominence. The results are remarkably distinct from and complementary to the standard hydrogen-bond-centered view of secondary structure. New insights include an unprecedented level of precision in describing the φ,ψ angles of both previously known and novel motifs, ordering of these motifs by their population density, a data-driven recommendation that the standard C^α_i…C^α_i + 3 < 7 Å criteria for defining turns be changed to 6.5 Å, identification of β-strand and turn capping motifs, and identification of conformational capping by residues in polypeptide II conformation. We further document that the conformational preferences of a residue are substantially influenced by the conformation of its neighbors, and we suggest that accounting for these dependencies will improve protein modeling accuracy. Although the CUEVAS-4D(r₁₀?₁₄) ‘parts list’ presented here is only an initial exploration of the complex (φ,ψ)₂ landscape of proteins, it shows that there is value to be had from this approach, and it opens the door to more in-depth characterizations at the (φ,ψ)₂ level and at higher dimensions.     

Electron microscope heteroduplex studies of sequence relations among plasmids of Escherichia coli: VIII. The structure of bacteriophage φ80d3ilv+su+7, including the mapping of the ribosomal RNA genes

The sequences present on the DNA of the transducing phage, φ80d₃ilv⁺su⁺7 have been mapped by electron microscope heteroduplex methods. In addition to some φ80 sequences, the phage DNA contains sequences from the extreme counterclockwise region and from the extreme clockwise region of the bacterial chromosomal part of F14. The former includes ilv, the latter a 16 S and a 23 S ribosomal RNA gene. These two regions are joined on the transducing phage DNA by the 2.8 to 8.5F sequence.By direct observation of the structure of the rRNA/DNA hybrids, the 16 S and 23 S genes have lengths of 1.38 ± 0.14 and 2.66 ± 0.17 kilobases. They are separated by a spacer of length 0.57 ± 0.13 kilobases.The rRNA genes (rrn) of φ80d₃ilv⁺su⁺7 are derived from and are identical with the rrnB gene set of F14. In heteroduplexes between the rrnB gene set of φ80d₃ilv⁺su⁺7, and the rrnA gene set of F14 we observe that there is a region of non-homology of length 0.25 ± 0.06 kilobases within the spacer sequence. This confirms observations in the preceding paper on the structure of out-of-register duplexes of the two rRNA gene sets of F14.A model for the integration and excision events involved in the formation of φ80d₃ilv⁺su⁺ 7 from φ80dmet(K) is proposed.     

Coiling of beta-pleated sheets

To form strongly twisted β-sheets, strands have to be coiled as well as twisted (Nishikawa &; Scherga, 1976). I show that strands coil in the appropriate right-handed direction if their main-chain torsion angles fulfil the following conditions: ψ_i ? ?φ_{i + 1}, ψ_{i + 1} > ?φ_{i + 2}, ψ_{i + 2} ? ?φ_{i + 3}, ψ_{i + 3} > ?φ_{i + 4}…Lactate dehydrogenase, pancreatic trypsin inhibitor, thermolysin and concanavalin A contain strongly twisted β-sheets and in each case the strands are coiled by their φ, ψ values fulfilling these conditions.     

Formation of a strong electric field resulting in the excitation of microplasma discharges at the edge of a dielectric film on a metal in a plasma flow

Results are presented from experimental and analytical studies of the processes resulting in the excitation of microplasma discharges (MPDs) on a metal surface partially covered with a thin dielectric film under the action of an external plasma flow in vacuum. It is shown experimentally that MPDs are excited at the interface between the open metal surface and the region covered by the dielectric film. The probability of MPD excitation is investigated as a function of the thickness of the dielectric film deposited on the metal. It is found that, for a film thickness of 1 μm, the probability of MPD excitation is close to unity. As the film thickness decreases below ~10 nm or increases above ~10 μm, the probability of MPD excitation is reduced by more than two orders of magnitude. A two-dimensional kinetic numerical code is developed that allows one to model the processes of Debye sheath formation and generation of a strong electric field near the edge of a finite-thickness dielectric film on a metal surface in a plasma flow for different configurations of the film edge. It is shown that the maximum value of the tangential component of the electric field is reached at the film edge and amounts to E _max ≈ |φ₀|/2d (where φ₀ < 0 is the electric potential applied to the metal and d is the film thickness), which for typical conditions of experiments on the excitation of MPDs on metal surfaces (φ₀ ≈–400 V, d ≈ 1 μm) yields E _max ≈ 2 MV/cm. The results of kinetic simulations confirm the qualitative idea about the mechanism of the formation of a strong electric field resulting in the excitation of MPDs at the edge of a dielectric film on a metal surface in a plasma flow and agree with experimental data.     

Local mobility of the lac repressor molecule

The rotational mobility of lac repressor from Escherichia coli was investigated by nanosecond fluorescence depolarization spectroscopy. A single rotational correlation time (φ) of the repressor was observed by monitoring the emission anisotropic decay of the intrinsic tryptophan fluorescence. The small value of φ (9·5 ns) suggests that one or both of the two tryptophan residues in the repressor are located in a flexible segment of the protein molecule. This segmental flexibility is enhanced by binding of inducer (isopropyl-β-d-thiogalactoside) to the repressor while it is restrained by binding of anti-inducer (glucose) or small DNA fragments, as indicated by the changes in φ. Further time-dependent emission anisotropy studies with an extrinsic fluorescent probe, N-(iodoacetylaminoethyl)-5-naphthylamine-1-sulfonate, covalently attached to the repressor yielded two rotational correlation times. The shorter φ_S (6·7 ns) also corresponds to a segmental flexibility whereas the longer φ_L (118 ns) represents the rotational motion of the entire repressor molecule. Both the values of φ_S and φ_L vary by addition of inducer or anti-inducer in a manner similar to that observed for the intrinsic tryptophan fluorescence but they are insensitive to addition of DNA fragments. The changes in local mobility of the lac repressor molecule observed in these studies may provide some insight into how inducer (or anti-inducer) destabilizes (or stabilizes) the repressor-operator complex.     

Electron microscope heteroduplex studies of sequence relations among plasmids of Escherichia coli. VI. Mapping of F14 sequences homologous to phi 80dmetBJF and phi 80dargECBH bacteriophages

The positions of the metBJF and the argECBH sequences on F14 have been mapped by studying heteroduplexes of F14 with φ80dmet and φ80darg transducing phage DNAs. The structures of the DNAs of the transducing phage φ80d-metB isolated by Konrad (1969), of two φ80dmetB phages isolated by Press et al. (1971), and of some derived φ80darg phages, have been determined. They all have complex structures. In addition to the bacterial chromosome sequences corresponding to the met and arg genes, they contain certain F sequences, which have been recognized as active in F-related recombination events. Plausible models for the integration and excision events leading to the formation of the phage DNA molecules are proposed.     

Suppression of macrophage activation by peritoneal fluid from patients with endometriosis

To investigate the effects of peritoneal fluid from patients with endometriosis on mouse peritoneal macrophages (Mφ), peritoneal fluid from endometriosis patients (n=15) were added to a monolayer of C3H/HeJ mouse peritoneal Mφ. Tumor necrosis factor-producing activity was measured by the L929 assay activated with FK-23 (a preparation of heat-killed Enterococcus faecalis). Tumor necrosis factor-producing activity of C3H/HeJ mouse peritoneal Mφ incubated with peritoneal fluid was suppressed in 14 endometriosis patients. Interestingly, in nine endometriosis patients, tumor necrosis factor-producing activity was much lower than seen with mouse peritoneal Mφ incubated with corticosterone. Peritoneal fluid contains suppressive properties for the activation of peritoneal Mφ, which might allow the implantation of free endometrial cells or the metaplastic phenomena stimulated by retrograde menstruation.     

Synthesis,spectroscopy, electrochemistry,and photochemistry of a series of M(bpym)2Cl2 (M=Mn(II), Co(II), Ni(II), and Cu(II)) complexes. Precursor complexes in the preparation of polymetallic systems

The synthesis, aqueous absorption and reflectance spectra, cyclic voltammetry and ligand field photochemistry of a series of M(bpym)₂Cl₂ (M=Mn(II), Co(II), Ni(II), Cu(II) and bpym=2,2′-bipyrimidine) are reported here. Ligand field electronic spectral assignments are made by comparison to analogous M(bpy)₂Cl₂(s) (bpy=2,2′-bipyridine) and M(bpym)₃²⁺ complexes. Ligand field absorption maxima are shifted to lower energy as a result of bpym loss vs. M(bpym)₃²⁺ complexes. Metal to ligand charge transfer absorption energies increase as a result of d_M orbital stabilization vs. M(bpym)₃²⁺ complexes. Cyclic voltammetry indicates ring opening upon reduction of the complexes. The complexes are photochemically inert (φ_max<0.002) at the irradiated wavelengths.     

The conversion of 5α-lanost-24-ene-3β,9α-diol and parkeol into poriferasterol by the alga Ochromon as malhamensis

The 4,4-dimethylsterols 4α-lanost-24-ene-3β,9α-diol-[2-³H₂] and parkeol-[2-³H₂] were synthesized from lanosterol and subsequently incubated with cultures of Ochromonas malhamensis. 5α-Lanost-24-ene-3β,9α-diol was converted into poriferasterol with three times the efficiency of parkeol. Clionasterol was also found to be labelled from both parkeol and 5α-lanost-24-ene-3β,9α-diol. No significant incorporation of radioactivity into sterols was obtained after feeding 5α-lanost-24-ene-3β,9α-diol to higher plants, the chlorophyte alga Trebouxia, yeast or a cell free homogenate of rat liver.     

Design and synthesis of pyrazolo[3,4-d]pyrimidinone derivatives: Discovery of selective phosphodiesterase-5 inhibitors

A novel series of 1,6-disubstituted pyrazolo[3,4-d]pyrimidin-7-one derivatives, 2a-h, 4a-d, 5 and 6, were successfully synthesized, which showed promising, and potent inhibition of phosphodiesterase 5 (PDE5). The inhibitory activities of 5, 4b, 2a, 2d, 2f, 4d and 4a against PDE5 were similar to that of sildenafil (100%). These compounds exhibited potent relaxant effects on isolated rat cavernosum tissue with pEC₅₀ values ranging from 8.31 to 5.16 µM. Pyrazolo[3,4-d]pyrimidin-7-one scaffolds have been rationally designed via consecutive molecular modelling studies prior to their synthesis and biological evaluation. In addition, the results of the pharmacophore-based virtual screening revealed that 1v0p_PVB might have promising activity as a PDE-5 inhibitor.     

EFFECTS OF TEMPERATURE ON GROWTH,LIGHT ABSORPTION,AND QUANTUM YIELD IN DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE)1

The effects of growth temperature on the marine chlorophyte Dunaliella tertiolecta Butcher were studied to provide a more mechanistic understanding of the role of environmental factors in regulating bio-optical properties of phytoplankton. Specific attention was focused on quantities that are relevant for modeling of growth and photosynthesis. Characteristics including chlorophyll a (chl z)-specific light absorption (a*_ph(λ)), C:chl a ratio, and quantum yield for growth (φ_μ) varied as functions of temperature under conditions of excess light and nutrients. As temperature increased over the range examined (12°-28°C), intracellular concentrations of chl a increased by a factor of 2 and a*_ph(λ) values decreased by more than 50% at blue to green wavelengths. The lower values of a*_ph(λ) were due to both a decrease in the abundance of accessory pigments relative to chl a and an increase in pigment package effects arising from higher intracellular pigment concentrations. Intracellular pigment concentration increased as a consequence of higher cellular pigment quotas combined with lower cell volume. At high growth temperatures, slightly more light was absorbed on a per-cell-C basis, but the dramatic increases in growth rate from μ= 0.5 d^?1 at 12° C to μ= 2.2 d^?1 at 28°C were primarily due to an increase in φ_μ (0.015–0.041 mol C (mol quanta)^?1). By comparison with previous work on this species, we conclude the effects of temperature on a*_ph(λ) and φ_μ are comparable to those observed for light and nutrient limitation. Patterns of variability in a*_ph(λ)and φ_μ as a function of growth rate at different temperatures are similar to those previously documented for this species grown at the same irradiance but under a range of nitrogen-limited conditions. These results are discussed in the context of implications for bio-optical modeling of aquatic primary production by phytoplankton.     

A technique for mapping transfer RNA genes by electron microscopy of hybrids of ferritin-labeled transfer RNA and DNA: the phi-80hpsu+3-system

A method for mapping transfer RNA genes on single strands of DNA is described. tRNA is covalently coupled to the electron-opaque label, ferritin. The ferritinlabeled tRNA, Fer-tRNA, is hybridized to a single strand of DNA, or to a single- strand region of a DNA in a heteroduplex. The sites where the Fer-RNA binds to the complementary sequence on the DNA are then mapped by electron microscopy. Several alternative coupling procedures are described (see Fig. 1). In HzI a — COCH₂Br group is attached to ferritin by acylation. 3'-Oxidized tRNA is joined to HSRCONHNH₂ by hydrazone formation. Ferritin is then coupled to tRNA by reaction of the CBr and SH bonds. In the BI procedure a lysine amino group of ferritin is coupled by Schiff base formation with 3'-oxidized RNA. The conjugate is stabilized by borohydride reduction. In the BII procedure, a —COCH₂Br group is attached to ferritin. (H₂NCH₂CH₂S—)₂ is coupled to oxidized tRNA by Schiff base formation and borohydride reduction. An SH group is exposed by reduction. This HS-tRNA is coupled to a —COCH₂Br group attached to ferritin. All the procedures work but BII is recommended. Methods for purifying the Fer-tRNA and the Fer-tRNA-DNA hybrid are described. For the transducing phages, φ80hpsu^+,?_III and φ80hpsu^?_III, the DNA molecules each carry a piece of bacterial DNA of length 0·066±0·007 λ unit (3100 nucleotide pairs; we find the length of λ is 8·99 φX174 units) replacing a piece of phage DNA of φ80h of length 0·045±0·005 λ unit. The left junction of this bacterial DNA with phage DNA (referred to as P-B′) is at or close to the att site. The two tandem tyrosine genes of φ80hpsu^+,?_III and the single tRNA gene of φ80hpsu^?_III have been mapped at a position 1100 nucleotides to the right of the left (P·B′) junction of phage DNA and bacterial DNA, by hybridizing Escherichia coli Fer-tRNA to φ80hpsu_III/φ80h heteroduplexes. The separation of the two ferritin labels in φ80hpsu^+,?_III hybrids gives 140±20 nucleotides as the size of a single tyrosine tRNA gene.     

Secondary structure in transfer RNA genes

The bacterial strand of the heteroduplex of λh80 dglyTsu⁺₃₆tyrTthrT with λh80 carries a cluster of three transfer RNA genes. The bacterial strands of the heteroduplexes of φ80hpsu^+,?_III and φ80hpsu^?_III with φ80h carry two and one genes for tyrosine tRNA, respectively. When these heteroduplexes are spread under weakly denaturing conditions (low formamide), secondary structure features consisting of one or several closely clustered, short duplex regions (folds) are observed. The features map at the positions of the tRNA gene clusters. They are not seen if the DNA is hybridized to Escherichia coli tRNA. It is concluded that the secondary structure features are due to self-complementary sequences in the tRNA genes. In some cases, the duplex folds appear to involve base pairing between sequences on different tRNA genes of a cluster and may also involve the spacer sequences between the tRNA sequences.     

Isoxazole-tethered diarylheptanoid analogs: Discovery of a new drug-like PAR2 antagonist

A new class of isoxazole-tethered diarylheptanoids having characteristic 1,3-syn-diol and 1,3-anti-diol chemophoric moieties, e.g. 4a–d and 5a–c respectively, have been designed and synthesized starting from d-glucose following a stereo-conserved general synthetic strategy. The isoxazole heterocycle was installed using our recently elaborated methodology deploying Magtrieve? as a selective oxidizing agent. Two of these new analogs 4a and 5a exhibited significantly improved in vitro drug-like properties including solubility, metabolic stability, cell permeability and lack of nonspecific cytotoxicity when compared with curcumin-I. In a HEK293 cell-based intracellular calcium [Ca²⁺]_i release assay, 4a and 5a, when tested at 30?μM, inhibited the trypsin agonist induced protease-activated receptor-2 (PAR2) activity by 80% and 70% respectively. IC₅₀ of 4a (SB70) has been determined as 6?μM which is in the same range of current benchmarks for PAR2 antagonists.     

Enzymes of d-fructose catabolism in species of Beneckea and Photobacterium

Cell-free extracts of strains representative of the genera Beneckea and Photobacterium catalyzed a P-enol-pyruvate dependent phosphorylation of d-fructose. The resulting product, fructose-1-P, was converted to fructose-1,6-P₂ by 1-P-fructokinase. Both activities were inducible, being present in d-fructose-grown cells and reduced or absent in d-gluconate- (or succinate-) grown cells.     

Energy fluxes and driving forces for photosynthesis in Lemna minor exposed to herbicides

Analysis of fast chlorophyll fluorescence rise OJIP was carried out to assess the impact of diuron, paraquat and flazasulfuron on energy fluxes and driving forces for photosynthesis in Lemna minor. Results showed that diuron and paraquat treatment produced major changes in electron transport in active reaction centres (RCs). However, diuron had a more pronounced effect on the yield of electron transport per trapped exciton (ψ₀) than on the yield of primary electron transport (φP₀)$({\phi }_{{\text{P}}_0})$ showing that dark reactions are more sensitive to diuron than light-dependent reactions. In contrast, paraquat treatment effects were not due to a target-specific action on those dark and light reactions. Paraquat also induced a marked surge in the total absorption of photosystem II (PSII) antenna chlorophyll per active RC displaying a large increase of the dissipation of excess energy through non-photochemical pathways (thermal dissipation processes). Flazasulfuron induced a slight decrease of both the total driving force for photosynthesis and the quantum yield of electron transport beyond Q_A⁻ combined to a small but significant increase of the non-photochemical energy dissipation per RC (DI₀/RC). We conclude that energy fluxes and driving force for photosynthesis generate useful information about the behaviour of aquatic plant photosystems helping to localize different target sites and to distinguish heterogeneities inside the PSII complexes. Regardless of the active molecule tested, the DF_ABS, φE₀${\phi }_{{\text{E}}_0}$, DI₀/RC and/or ET₀/RC parameters indicated a significant variation compared to control while φP₀${\phi }_{{\text{P}}_0}$ (F_V/F_M) showed no significant inhibition suggesting that those parameters are more sensitive for identifying a plant’s energy-use efficiency than the maximum quantum yield of primary PS II photochemistry alone.     

High-Level Heterologous Production of d-Cycloserine by Escherichia coli

Previously, we successfully cloned a d-cycloserine (d-CS) biosynthetic gene cluster consisting of 10 open reading frames (designated dcsA to dcsJ) from d-CS-producing Streptomyces lavendulae ATCC 11924. In this study, we put four d-CS biosynthetic genes (dcsC, dcsD, dcsE, and dcsG) in tandem under the control of the T7 promoter in an Escherichia coli host. SDS-PAGE analysis demonstrated that the 4 gene products were simultaneously expressed in host cells. When l-serine and hydroxyurea (HU), the precursors of d-CS, were incubated together with the E. coli resting cell suspension, the cells produced significant amounts of d-CS (350 ± 20 μM). To increase the productivity of d-CS, the dcsJ gene, which might be responsible for the d-CS excretion, was connected downstream of the four genes. The E. coli resting cells harboring the five genes produced d-CS at 660 ± 31 μM. The dcsD gene product, DcsD, forms O-ureido-l-serine from O-acetyl-l-serine (OAS) and HU, which are intermediates in d-CS biosynthesis. DcsD also catalyzes the formation of l-cysteine from OAS and H₂S. To repress the side catalytic activity of DcsD, the E. coli chromosomal cysJ and cysK genes, encoding the sulfite reductase α subunit and OAS sulfhydrylase, respectively, were disrupted. When resting cells of the double-knockout mutant harboring the four d-CS biosynthetic genes, together with dcsJ, were incubated with l-serine and HU, the d-CS production was 980 ± 57 μM, which is comparable to that of d-CS-producing S. lavendulae ATCC 11924 (930 ± 36 μM).     

Antimicrobial activity of quinoxaline 1,4-dioxide with 2- and 3-substituted derivatives

Quinoxaline is a chemical compound that presents a structure that is similar to quinolone antibiotics. The present work reports the study of the antimicrobial activity of quinoxaline N,N-dioxide and some derivatives against bacterial and yeast strains. The compounds studied were quinoxaline-1,4-dioxide (QNX), 2-methylquinoxaline-1,4-dioxide (2MQNX), 2-methyl-3-benzoylquinoxaline-1,4-dioxide (2M3BenzoylQNX), 2-methyl-3-benzylquinoxaline-1,4-dioxide (2M3BQNX), 2-amino-3-cyanoquinoxaline-1,4-dioxide (2A3CQNX), 3-methyl-2-quinoxalinecarboxamide-1,4-dioxide (3M2QNXC), 2-hydroxyphenazine-N,N-dioxide (2HF) and 3-methyl-N-(2-methylphenyl)quinoxalinecarboxamide-1,4-dioxide (3MN(2MF)QNXC). The prokaryotic strains used were Staphylococcus aureus ATCC 6538, S. aureus ATCC 6538P, S. aureus ATCC 29213, Escherichia coli ATCC 25922, E. coli S3R9, E. coli S3R22, E. coli TEM-1 CTX-M9, E. coli TEM-1, E. coli AmpC Mox-2, E. coli CTX-M2 e E. coli CTX-M9. The Candida albicans ATCC 10231 and Saccharomyces cerevisiae PYCC 4072 were used as eukaryotic strains. For the compounds that presented activity using the disk diffusion method, the minimum inhibitory concentration (MIC) was determined. The alterations of cellular viability were evaluated in a time-course assay. Death curves for bacteria and growth curves for S. cerevisiae PYCC 4072 were also accessed. The results obtained suggest potential new drugs for antimicrobial activity chemotherapy since the MIC's determined present low values and cellular viability tests show the complete elimination of the bacterial strain. Also, the cellular viability tests for the eukaryotic model, S. cerevisiae, indicate low toxicity for the compounds tested.