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PubMed1982

Synthesis of di- and tri-saccharides corresponding to receptor structures recognised by pyelonephritogenic E. coli fimbriae (pili).

Syntheses are described of di- and tri-saccharides required for studies of the inhibition of adhesion by means of fimbriae of pyelonephritogenic E. coli bacteria to epithelium cells in the urinary tract containing suitable receptor sites. The disaccharides are the rho-nitrophenyl and methyl glycosides of 4-omicron-alpha-D-galactopyranosyl-beta-D-galactopyranose, and the trisaccharides are the rho-nitrophenyl and methyl glycosides of 4-omicron-(4-omicron-alpha-D-galactopyranosyl-beta-D-galactopyranosyl)-beta- D-glucopyranose. The key aglycons were the 1,2,3,6-tetrabenzoate of alpha-D-galactose and the 1,2,3,6,-2',3',6'-heptabenzoate of alpha-lactose. Glycosidations were performed with 2,3,4,6-tetra-omicron-benzyl-alpha-D-galactopyranosyl chloride as glycosylating agent and silver triflate as promoter.

Cell Adhesion↗

PubMed1983

Aspartate and glutamate induced reductions in extracellular free calcium and sodium concentration in area CA1 of 'in vitro' hippocampal slices of rats.

Extracellular Ca2+ and Na+ were simultaneously measured with ion selective electrodes in the CA1 pyramidal cell layer of rat hippocampal slices. Repetitive stimulation of the Schaffer collateral/commissural fiber system led to decreases in [Ca2+] omicron and [Na+] omicron (delta Ca, delta Na) by up to 0.5 mM and 13 mM, respectively. Iontophoretic application of glutamate or aspartate caused dose-dependent delta Ca of more than 1 mM and delta Na of more than 45 mM. Such ionic alterations were smaller in the presence of GABA or of the Ca2+ antagonists Ni2+ and Mg2+. Ca2+ signals were diminished when evoked in low-Na+ bathing medium and Na+ signals were reduced in Ca2+-free solutions. Thus glutamate- and aspartate-dependent decreases in [Na+] omicron and [Ca2+] omicron appear to be caused by 3 different mechanisms: Na+ movement through amino acid-activated ionophores; Ca2+ movement through selective channels, and Ca2+-dependent Na+ movement.

Animals↗

PubMed1987

Morphological and chiral symmetry breaking in reaction-diffusion systems.

Morphological and chiral symmetry breaking in reaction-diffusion systems is considered on the basis of the theory of imperfect codimension-two bifurcations. A new type of pattern selection with two triggers is elucidated: (1) morphologically asymmetric structures displaying optical activity can probably be originated from initially racemic and homogeneous conditions when chiral interaction, having the characteristic strength delta (such as electroweak interaction and circularly polarized light) as well as external field, having the characteristic strength eta (such as gravitational field and electrostatic field) are considered; (2) the selective sensitivity of molecular chirality and morphological asymmetry is omicron(delta 1/3) and omicron(eta 1/3), respectively; the sensitivity of mode-mode interaction between chiral polarization and concentration vector is omicron(delta 2/3) or omicron(eta 2/3), respectively. The relation of these conclusions to the life problem is discussed briefly.

Amino Acids↗

PubMed2004

Mitochondrial-derived free radicals mediate asbestos-induced alveolar epithelial cell apoptosis.

Asbestos causes pulmonary toxicity by mechanisms that in part involve reactive oxygen species (ROS). However, the precise source of ROS is unclear. We showed that asbestos induces alveolar epithelial cell (AEC) apoptosis by a mitochondrial-regulated death pathway. To determine whether mitochondrial-derived ROS are necessary for causing asbestos-induced AEC apoptosis, we utilized A549-rho(omicron) cells that lack mitochondrial DNA and a functional electron transport. As expected, antimycin, which induces an oxidative stress by blocking mitochondrial electron transport at complex III, increased dichlorofluoroscein (DCF) fluorescence in A549 cells but not in A549-rho(omicron) cells. Compared with A549 cells, rho(omicron) cells have less asbestos-induced ROS production, as assessed by DCF fluorescence, and reductions in total glutathione levels as well as less caspase-9 activation and apoptosis, as assessed by TdT-mediated dUTP nick end labeling staining and DNA fragmentation. A mitochondrial anion channel inhibitor that prevents ROS release from the mitochondria to the cytoplasm also blocked asbestos-induced A549 cell caspase-9 activation and apoptosis. Finally, a role for nonmitochondrial-derived ROS with exposure to high levels of asbestos (50 microg/cm(2)) was suggested by our findings that an iron chelator (phytic acid or deferoxamine) or a free radical scavenger (sodium benzoate) provided additional protection against asbestos-induced caspase-9 activation and DNA fragmentation in rho(omicron) cells. We conclude that asbestos fibers affect mitochondrial DNA and functional electron transport, resulting in mitochondrial-derived ROS production that in turn mediates AEC apoptosis. Nonmitochondrial-associated ROS may also contribute to AEC apoptosis, particularly with high levels of asbestos exposure.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed2026

Global disparities in COVID-19 vaccine coverage associated with trajectories of SARS-CoV-2 adaptation.

BACKGROUND: Vaccination serves as an effective intervention for health promotion and disease prevention across the socioecological systems and has played an important role during the COVID-19 pandemic. However, global disparities in vaccine coverage have increased uncertainty about the trajectories of viral adaptation, and the potential interplay between SARS-CoV-2 adaptation and vaccine rollout warrants further quantification. METHODS: Using over 13 million SARS-CoV-2 genomes across 86 countries from March 2020 to September 2022, we analyzed nonlinear associations between SARS-CoV-2 adaptation and vaccination coverage, considering public health and social measures, international travel, and infection dynamics, before and after the emergence of Omicron. Additionally, we examined the relationship between SARS-CoV-2 adaptation and COVID-19 mortality. RESULTS: During the pre-Omicron period, we found positive associations between nonsynonymous to synonymous divergence (dN/dS) ratios in the S1 subunit and medium levels of adjusted vaccine coverage (effect size: 0.96 [95% CI 0.47, 1.45]), while the association became insignificant at high levels (effect size: -1.89 [95% CI -4.20, 0.43]). However, no significant associations were found when Omicron dominated, possibly due to the immune escape ability of Omicron variants and the complex immune landscape shaped by mass hybrid immunity. Moreover, we observed evidence of dynamic interdependence and positive correlations between COVID-19 mortality and SARS-CoV-2 adaptation, with COVID-19 mortality interpreted as a proxy for uncontrolled viral spread. CONCLUSIONS: Our findings suggest a complex nonlinear relationship between vaccine-induced immunity and SARS-CoV-2 adaptation, with high vaccine coverage potentially linked to lower positive selection. We also observed directional coupling between COVID-19 mortality and SARS-CoV-2 adaptation. This may have implications for fair and fast vaccination in pandemic preparedness and response. CLINICAL TRIAL NUMBER: Not applicable.

Humans↗

PubMed1995

Reactivity of essential cysteine and lysine residues present at the catalytic domain of pig heart mitochondrial malate dehydrogenase.

Pig heart mitochondrial malate dehydrogenase was inactivated very rapidly by omicron-phthalaldehyde as compared to 5,5'-dithio bis(2-nitrobenzoic acid) and pyridoxal 5'-phosphate. The omicron-phthalaldehyde reaction followed pseudo first order kinetics, and a second order rate constant of 38 M-1 S-1 was obtained. Cysteine and lysine residues participating in the omicron-phthalaldehyde reaction are located in the NADH binding region of malate dehydrogenase as shown by protection experiments. The decrease in the rate of inactivation in the presence of NADH was used to determine the dissociation constant of the enzyme-NADH complex. pH dependent studies and molar transition energy calculations of the omicron-phthalaldehyde-inactivated enzyme have indicated that cysteine and lysine residues involved in the isoindole derivative formation are located in a hydrophobic environment at the coenzyme binding site.

Animals↗

PubMed2004

Viral infection and Toll-like receptor agonists induce a differential expression of type I and lambda interferons in human plasmacytoid and monocyte-derived dendritic cells.

In humans, the type I interferon (IFN) family consists of 13 IFN-alpha subtypes, IFN-beta and IFN-omicron the newly discovered IFN-like family consists of IFN-lambda1, -lambda2 and -lambda3. We have investigated the expression of type I and lambda IFN genes following virus infections or Toll-like receptor (TLR) triggering in monocyte-derived DC (MDDC) and plasmacytoid DC (pDC). We found that all IFN-alpha, -beta, -omicron and -lambda subtypes are expressed in influenza-virus-infected MDDC or pDC. Conversely, differential type I IFN gene transcription was induced in MDDC and pDC stimulated by specific TLR agonists. TLR-9 stimulation by CpG DNA induced the expression of all IFN-alpha, -beta, -omicron and -lambda subtypes in pDC, whereas TLR-4 stimulation by LPS, or TLR-3 stimulation by poly I:C, induced only IFN-beta and IFN-lambda gene expression in MDDC. The expression pattern of IFN regulatory factor (IRF)-5 and IRF-7 in MDDC and pDC was also determined. IRF-5 was constitutively expressed in the two DC subsets whereas IRF-7 was constitutive in pDC but its expression was induced along MDDC maturation. Overall, our data indicate that the coordinated expression of IFN-lambda with IFN-beta would be of crucial importance for the maturation of DC.

Cell Line↗

PubMed2025

Dissecting Sex-Specific Pathology in K18-hACE2 Transgenic Mice Infected With Different SARS-CoV-2 Variants.

Sex-biased differences in COVID-19 outcomes in relation to individual SARS-CoV-2 variants are not well understood. In this study, lungs and nasal cavities of age-matched female and male K18-hACE2 transgenic mice were collected for dissecting sex-specific differences in pathology after infection of SARS-CoV-2 614 G, Delta, or Omicron variant. Overall, Delta infection induced the most severe inflammation and pathology in nasal cavity and lung followed by the 614 G, then Omicron variant. Sex differences in host responses to SARS-CoV-2 infection were variant-specific. Delta-infected males showed increased pulmonary infiltration of CD163+ "M2" macrophages, Ly6G+ neutrophils, and NKR-P1C + NK cells during early onset of infection, and elevated lung inflammatory cytokines such as IL-10, IL-6, and IP-10 than Delta-infected females. Conversely, females had increased lung CD4 + T cell recruitment after Omicron infection and significantly elevated lung MCP-1 secretion after Delta infection than males. Lung spatial transcriptomics data revealed that Delta-infected females had enriched gene pathways related to humoral immune response and interferon signaling, while males had enriched pathways associated with extracellular matrix production, chemokine signaling, and cell chemotaxis. Taken together, this study highlights the complex infection dynamics with respect to individual SARS-CoV-2 variants and underscores the importance of sex as a confounding factor for COVID-19 pathology.

Animals↗

PubMed2005

A phenolic glucoside isolated from Prunus serrulata var. spontanea and its peroxynitrite scavenging activity.

A new phenolic glucoside (1), pursargentoside, was isolated from the leaves of Prunus serrulata var. spontanea, along with three other known compounds, orobol 7-omicron-glucoside (2), 1beta, 2alpha, 3alpha, 24-tetrahydroxy-urs-12-en-28-oic acid (3), and chlorogenic acid (4). The structure of pursargentoside (1) was identified by spectroscopic data analysis including 1D and 2D NMR spectroscopy, as 2-omicron-beta-(6'-benzoyl)-glucopyranosyl omicron-(Z)-coumaric acid. Compounds 1, 2, and 4 exhibited ONOO scavenging activity, whereas compound 3 was determined to be virtually inactive.

Free Radical Scavengers↗

PubMed2004

Triterpenoid saponin from Viola hondoensis W. Becker et H Boss. and their effect on MMP-1 and type I procollagen expression.

Bioassay-guided fractionation has led to the isolation of triterpenoid saponins such as Acutoside A (3-omicron-[omicron-beta-D-glucopyranosyl-(1 --> 2)-omicron-beta-D-glucopyranosyl] oleanolic acid) from the whole plants of Viola hondoensis. Among them, Saponin 1 exhibited potent inhibitory activity against matrix metalloproteinase (MMP)-1, and prevented the UV-induced changes in the MMP-1 expression. In addition, compound was isolated from this plant for the first time.

Blotting, Western↗

PubMed2000

Osmotically evoked shrinking of guard-cell protoplasts causes vesicular retrieval of plasma membrane into the cytoplasm.

The dye FM1-43 was used alone or in combination with measurements of the membrane capacitance (Cm) to monitor membrane changes in protoplasts from Vicia faba L. guard cells. Confocal images of protoplasts incubated with FM1-43 (10 microM) at constant ambient osmotic pressure (pi omicron) revealed in confocal images a slow internalisation of FM1-43-labelled membrane into the cytoplasm. As a result of this process the relative fluorescence intensity of the cell interior (fFM,i) increased with reference to the total fluorescence (fFM,t) by 7.4 x 10(-4) min(-1). This steady internalisation of dye suggests the occurrence of constitutive endocytosis under constant osmotic pressure. Steady internalisation of FM1-43 labelled membrane caused a prominent staining of a ring-like structure located beneath the plasma membrane. Abrupt elevation of pi omicron by 200 mosmol kg(-1) caused, over the first minutes of incubation, a rapid internalisation of FM1-43 fluorescence into the cytoplasm concomitant with a decrease in cell perimeter. Within the first 5 min the cell perimeter decreased by 7.9%. Over the same time fFM,i/fFM,t increased by 0.13, reflecting internalisation of fluorescent label into the cytoplasm. Combined measurements of Cm and total fluorescence of a protoplast (fFM,p) showed that an increase in pi omicron evoked a decrease in Cm but no change in fFM,p. This means that surface contraction of the protoplast is due to retrieval of excess membrane from the plasma membrane and internalisation into the cytoplasm. Further inspection of confocal images revealed that protoplast shrinking was only occasionally associated with internalisation of giant vesicles (median diameter 2.7 microm) with FM 1-43-labelled membrane. But, in all cases, osmotic contraction was correlated with a diffuse distribution of FM1-43 label throughout the cytoplasm. From this, we conclude that endocytosis of small vesicles into the cytoplasm is the obligatory process by which cells accommodate an osmotically driven decrease in membrane surface area.

Cell Membrane↗

PubMed1996

Postcolumn excitation of aflatoxins using cyclodextrins in liquid chromatography for food analysis.

Measurement of fluorescence increase was used for the comparative quantification of the effect that several cyclodextrins (alpha-, beta-, heptakis-2,6-beta-omicron-dimethyl- and gamma-) produce on the fluorescent response of aflatoxins B1 and G1. This constitutes a new chromatographic method with stability of the mobile phase, and shows general improvements in the chromatographic conditions with respect to other methods (especially those using an iodine reservoir as a postcolumn reactor). A C18-type column was used, with methanol-water (60:40, v/v) as the mobile phase. The excitation phase of the natural fluorescence of aflatoxins, a 10(-2) M solution of each cyclodextrin, was introduced postcolumn. The determination of the elution order aflatoxin G2 > G1 > B2 > B1 was performed for each phase in less than 15 min. As expected using an aqueous-alcoholic medium, an increase in the fluorescence response of aflatoxins with an unsaturated furanic ring was found to occur with all the cyclodextrins studied, except gamma-cyclodextrin. The observed increase was larger for heptakis-2,6-beta-omicron-dimethyl- than for beta-cyclodextrin (to our knowledge, the only cyclodextrin previously described in the literature to serve for the determination of aflatoxins). The difference is of the order of 70.1-fold in the case of aflatoxin G1 and 45.2-fold in the case of aflatoxin B1. The detection limit in the mobile phase used was determined (for aflatoxin B1) for beta-cyclodextrin and 2,6-beta-omicron-dimethylcyclodextrin (signal-to-noise ratio 1:3) to be 4 and 9 mg 1(-1), respectively.

Aflatoxin B1↗

PubMed1980

High-performance liquid chromatography of acid-stable and acid-labile phosphoamino acids.

A high-performance liquid chromatographic system has been developed which permits the separation of both acid-stable and acid-labile phosphoamino acids. An anion-exchange resin and two buffers of different ionic strength and near neutral pH are used. A low-ionic-strength buffer is used for the separation of N-omega-phosphoarginine and N-epsilon-phospholysine, while the higher-ionic-strength buffer permits the clear separation of tau-phosphohistidine, omicron-phosphoserine and omicron-phosphothreonine. An in-stream fluorometric detection system using omicron-phthalaldehyde permits the rapid analysis of samples containing as little as 25 pmoles of phosphoamino acid. This method has been applied to the detection of tau-phosphohistidine from alkaline digests of chemically phosphorylated calf thymus histone 4 and bovine myelin basic protein.

Amino Acids↗

PubMed1978

Quantitative analysis of beta-phenylpyruvic acid by single ion monitoring. Evaluation of isomeric internal standards.

Quantitative single ion monitoring of beta-phenylpyruvic acid at high sensitivity is possible after derivatization first with omicron-phenylenediamine and then with a silylating reagent. The resulting o-trimethyl-silyl-quinoxalinol (O-TMS-Q) has previously been shown to be highly stable during storage and on chromatography. As an internal standard the isomeric omicron-methylphenylglyoxylic (omicron-toluylformic) acid is introduced. The mass spectra of both O-TMS-Q's are characterized by abundant [M]+. at m/e 308. The concept of "class specific metabolic profiling" is discussed in relation to quantitative gas chromatography--mass spectrometry detection of aliphatic and aromatic alpha-ketoacids.

Chromatography, Gas↗

PubMed1997

Development of enzyme immunoassay of 2'-deoxycytidine.

In order to study 2'-deoxycytidine (2'-dCyd) as a possible prognostic marker in cancer chemotherapy, an enzyme immunoassay (EIA) was developed. 2'-dCyd as a hapten was succinylated and two omicron-monosuccinyl-2'-dCyd's were purified by high performance liquid chromatography and identified by mass spectrometry and 1H-NMR. Two antigens were prepared by conjugating two omicron-succinyl derivatives with keyhole limpet hemocyanin (KLH) as a carrier. Both antigen produced specific antibodies to 2'dCyd in BALD/c mice. The spleen cells of one mouse immunized with 5'-omicron-succinyl-2'-dCyd-KLH were hybridized with myeloma cells. One monoclone selected produced a specific antibody. A convenient EIA was attained by using the monoclonal antibody.

Animals↗

PubMed1982

Recognition masking-level differences for 10 CID W-1 spondaic words.

Psychometric functions for the S omicron N omicron and S pi N omicron conditions and masking level differences were obtained for a subgroup of 10 words having the largest masking-level differences of 36 CID W-1 spondaic words. The mean masking-level difference obtained from 36 young normal adults was 9.4 dB with a standard deviation of 1.2 dB. The smallest masking-level difference of 7.4 dB was suggested as the low cut-off for normalcy. A shorter version of the masking-level difference procedure was suggested for clinical implementation. The subgroup of 10 words may permit a wider separation between normal and abnormal performance, and thus may enhance the clinical utility of the masking-level difference task for speech recognition. Because the magnitude of the masking-level difference will vary with the materials and procedures used, each clinic must establish its own norms.

Adult↗

PubMed1975

Resolution of the potassium ion pump in muscle fibers using barium ions.

When frog sartorius muscles recover from Na enrichment in the presence of external K, net K entry into the fibers occurs by both passive movement and active inward transport via a K pump. Under normal conditions, it has not been possible to experimentally distinguish these processes. Fractionation into the flux components must be accomplished from inferences concerning the K conductance or permeability during a period of rapid Na extrusion. The best estimates indicate that 60-80% of the K entry occurs via the K pump. In the presence of Ba ions, the membrane permeability to K is very much reduced. Under these conditions, Na-enriched muscles underwent a normal recovery in the presence of external K, and the amount of inward K movement due to the K pump rose to over 90% of the total K entry. The characteristics of the K pump studied by this means were: (a) essentially complete inhibition by 10(-4) M ouabain, (b) inhibition by [Na]omicron, (c) activation by [K]omicron according to a rectangular hyperbola in the absence of [Na]omicron, (d) linear activation by [Na]iota over a wide range in concentration, (e) zero or undetectably low pumping rate as [Na]iota leads to 0, (f) the number of Na ions actively transported per K ion actively transported is 1.4-1.7 normally and 1.1 in the presence of Ba.

Animals↗

PubMed1977

A genetic fine structure analysis of the suppressor 3 locus in Saccharomyces.

A meiotic fine structure map of a yeast tyrosine-inserting ochre suppressor, SUP3-omicron, was constructed. This was accomplished by examining ten intragenic suppressor-inactive revertants for their relationship to each other and to the original SUP3-omicron mutation. The second-site revertants map on both sides of the SUP3-omicron mutation. The meiotic map length based on the summation of short intervals is 45+/10(5) asci.

Chromosome Mapping↗