Free L1 Research Articles

A Pseudovirus Nanoparticle Displaying the Vaccinia Virus L1 Protein Elicited High Neutralizing Antibody Titers and Provided Complete Protection to Mice against Mortality Caused by a Vaccinia Virus Challenge.

The recent worldwide incidence of mpox infection and concerns about future emerging variants of mpox viruses highlight the need for the development of a new generation of mpox vaccines. To achieve this goal, we utilized our norovirus S nanoparticle vaccine platform to produce and evaluate two pseudovirus nanoparticles (PVNPs), S-L1 and S-J1. These PVNPs displayed the L1 neutralizing antigen target of the vaccinia virus and a yet-untested J1 antigen of the mpox virus, respectively, with the aim of creating an effective nanoparticle-based mpox vaccine. Each self-assembled PVNP consists of an inner shell resembling the interior layer of the norovirus capsid and multiple L1 or J1 antigens on the surface. The PVNPs improved the antibody responses toward the displayed L1 or J1 antigens in mice, resulting in significantly greater L1/J1-specific IgG and IgA titers than those elicited by the corresponding free L1 or J1 antigens. After immunization with the S-L1 PVNPs, the mouse sera exhibited high neutralizing antibody titers against the vaccinia virus, and the S-L1 PVNPs provided mice with 100% protection against mortality caused by vaccinia virus challenge. In contrast, the S-J1 PVNPs induced low neutralizing antibody titers and conferred mice weak protective immunity. These data confirm that the L1 protein is an excellent vaccine target and that the readily available S-L1 PVNPs are a promising mpox vaccine candidate worthy of further development.

Phosphine and Selenoether peri-Substituted Acenaphthenes and Their Transition-Metal Complexes: Structural and NMR Investigations.

A series of peri-substituted acenaphthene-based phosphine selenoether bidentate ligands Acenap(iPr2P)(SeAr) (L1-L4, Acenap = acenaphthene-5,6-diyl, Ar = Ph, mesityl, 2,4,6-trisopropylphenyl and supermesityl) were prepared. The rigid acenaphthene framework induces a forced overlap of the phosphine and selenoether lone pairs, resulting in a large magnitude of through-space 4JPSe coupling, ranging from 452 to 545 Hz. These rigid ligands L1-L4 were used to prepare a series of selected late d-block metals, mercury, and borane complexes, which were characterized, including by multinuclear NMR and single-crystal X-ray diffraction. The Lewis acidic motifs (BH3, Mo(CO)4, Ag+, PdCl2, PtCl2, and HgCl2) bridge the two donor atoms (P and Se) in all but one case in the solid-state structures. Where the bridging motif contained NMR-active nuclei (11B, 107Ag, 109Ag, 195Pt, and 199Hg), JPM and JSeM couplings are observed directly, in addition to the altered JPSe in the respective NMR spectra. The solution NMR data are correlated with single-crystal diffraction data, and in the case of mercury(II) complexes, they are also correlated with the solid-state NMR data and coupling deformation density calculations. The latter indicate that the through-space interaction dominates in free L1, while in the L1HgCl2 complex, the main coupling pathway is via the metal atom and not through the carbon framework of the acenaphthene ring system.

Pro-angiogenic effect of a synthetic Cu(II) complex [CuII(L)2] [LH = tautomeric thiolate form of 2-ethoxybenzaldehyde-N(4)-dihexyl-3-thiosemicarbazone

Synthesis and structural characterization of a thiosemicarbazone derivative of Cu(II) [CuII(L)2] [LH = tautomeric thiolate form of 2-ethoxybenzaldehyde-N(4)-dihexyl-3-thiosemicarbazone (L1)] (1) is reported. From the structural characterization data, the metal centre in 1 is found to have in square planar geometry. Both the free ligand (L1) and the metal complex (1) showed pro-angiogenic activity on fertilized chicken eggs. In Chorio-Allantoic Membrane (CAM) assay, L1 was found to promote blood capillary growth by 31.5% in 24 h, whereas for 1 it was 40.0%. In aortic arch assay also, 1 showed better angiogenic potential than the free L1.

Zinc(II) and copper(II) complexes with N-substituted imines derived from 4-amino-1,2,4-triazole: Synthesis, crystal structure, and biological activity

Reactions of copper(II) and zinc(II) acetates with polynitrogen Schiff bases, namely 4-(pyridin-2-yl)methyleneamino-1,2,4-triazole (L1), 4-(pyridin-3-yl)methyleneamino-1,2,4-triazole (L2) and 4-(pyridin-4-yl)methyleneamino-1,2,4-triazole (L3), were studied. The reaction of Zn(OAc)2·2H2O and L1 gave crystals of trinuclear complex [Zn3(OAc)6(L1)2] (1). A similar reaction of Zn(OAc)2·2H2O and L2 resulted in 1D coordination polymer [Zn(OAc)2(L2)]n (2). The reactions of Cu(OAc)2·H2O with L2 or L3 gave crystals of 1D coordination polymer {[Cu2(OAc)4(L2)]·2MeCN}n (3) and binuclear complex [Cu2(OAc)2(L3)2]·2MeCN (4), respectively. The structures of the coordination compounds thus obtained were determined by single-crystal X-ray diffraction analysis. Complexes 1–4 demonstrated better antibacterial and antifungal activities in comparison with free L1, L2, and L3 ligands: the strongest antimicrobial activity was observed against E. coli for 2 and 3, and the highest antifungal activity was found for 1 and 2.

Platinum(II) complexes bearing asymmetrically substituted pivaloylthioureas: Synthesis, crystal structures, DFT and antioxidant studies

Three new platinum(II) complexes derived from asymmetrically di-substituted pivaloylthiourea ligands (L1–3) are synthesized and characterized by 1H, and 195Pt{1H} NMR. The ligands and PtL1–3 complexes display configurational E,Z isomerism evinced by distinct sets of 1H, 195Pt{1H} NMR resonances observed in dichloromethane‑d2. Single-crystal X-ray diffraction studies reveal a bidentate cis-PtL1–3 coordination mode, in which two sulfur and oxygen donor atoms bind to Pt(II) forming a six-membered chelate. In addition, the EE isomers were preferentially isolated in acetonitrile for cis-PtL1 and cis-PtL2, while ZZ was obtained for cis-PtL3 with N-phenyl substituent. The relative energies of the cis-ZZ-Pt-L1–3, cis-EZ-Pt-L1–3, cis-EE-Pt-L1–3 configurational isomers are obtained by DFT analysis at the M06-2X/def2-SVP level of theory using an implicit acetonitrile solvent. Moreover, the structural studies indicate a potential intra-electron transfer from dz2 (HOMO) to dx2-y2 (LUMO), with a reduced electron affinity at the LUMO level for the cis-ZZ/ZE/EE-Pt-L1–3 structures. The antioxidant capacity of the L1–3 ligands and cis-PtL1–3 were evaluated using the ORAC, DPPH radical scavenging and FRAP methods. The free L1–3 ligands showed higher antioxidant activities in comparison to their coordinated cis-PtL1–3 complexes.

Structures and Chromogenic Ion-Pair Recognition of a Catechol-Functionalized 1,8-Anthraquinone Macrocycle in Dimethyl Sulfoxide.

A lariat anthraquinone macrocycle functionalized with catechol (H2L) was synthesized via the Mannich reaction. The Mannich base H2L can be partially decomposed into L1·3H2O and HL1·NO3·2H2O in the presence of tetrabutylammonium hydroxide/Al(NO3)3·9H2O in dimethyl sulfoxide (DMSO). Free L1·3H2O is essentially coplanar, while protonated HL1·NO3·2H2O is highly distorted. Dark-green FeCl3·H2L·2H2O powder and Fe2(HL)2Cl4 crystal can be isolated from ethanol (C2H5OH) in high/low H2L concentration. Anthraquinone in H2L is essentially coplanar but distorted in Fe2(HL)2Cl4. The Fe(III) ion in Fe2(HL)2Cl4 adopts a less common five-coordination with three catecholate O and two Cl atoms in the dimer. The distortion of inbound C═O is much higher than that of outbound C═O in anthraquinone in all of these compounds. H2L responds to chlorides of Li+, Na+, K+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Fe3+, Cu2+, Zn2+, and Al3+ in a DMSO solution, which can be observed by differential pulse voltammetry, UV-vis, and 1H NMR. All of these metal ions shift Ep of anthraquinone to positive, especially the second reduction peak of anthraquinone. Fe3+, Zn2+, and Al3+ change the reduction of catechol fundamentally. H2L (0.50 mM) shows a chromogenic response to FeCl3 and Fe(NO3)3 to form uncommon 2:1 and 3:2 (H2L/Fe) complexes, both peaking at 748 nm in DMSO. In the presence of 2 equiv of sodium hydroxide (NaOH), the 748 nm absorbance shifts to 777 nm, identical with Fe2(HL)2Cl4 in DMSO. Different from the fast reaction between H2L and FeCl3, Fe(NO3)3 reacts with H2L rather slowly in DMSO. Catechol can coordinate to FeCl3 without any deprotonation in C2H5OH and DMSO. H2L also shows a chromogenic response to fluorides and hydroxides, which peak at 670 and 684 nm, respectively, in DMSO. The binding ratio between H2L and F-/OH- is 1:2. In a higher concentration of hydroxides, a 684 nm greenish-blue 1:2 complex forms immediately, which gradually transforms to a red complex and peaks at ∼530 nm in minutes at room temperature. No color change can be observed in an C2H5OH solution in the presence of OH-.

In Methanolic Solvent Synthesis of New MnII, CoII, NiII and CuII Schiff Base of Aromatic β Amino Acids: Spectroscopic, Thermal, Molecular Docking and Antimicrobial Studies

In this article, four new Schiff base complexes of Mn(II), Co(II), Ni(II) and Cu(II) complexes have been synthesized with two different compositions as [M(L)2Cl2] · nH2O and [M(L)2(H2O)2]Cl2 · nH2O [where L1 = benzoin-o-amino benzoic acid (aromatic β amino acid) and L2 = benzoin bromo-o-amino benzoic acid (aromatic β amino acid); M = MnII, CoII, NiII and CuII; n = 1, 2 and 4]. These Schiff base complexes were discussed by many tool of analyses like elemental analysis, magnetic susceptibility, molar conductance, mass spectra, infrared spectra "IR," proton nuclear magnetic resonance "1H-NMR," electronic spectral and thermogravimetric analysis (TG/DTG). These complexes have an electrolytic nature within range of 78–174 Ω1 cm–1 mol –1 based on conductance measurements. Magnetic moment and electronic spectral results deduced that the geometry of Mn2+, Co2+ and Ni2+ and Cu2+ complexes has an octahedral configuration. The number of coordinated and uncoordinated water molecules for the synthesized complexes were calculated based on the thermal analysis technique. The kinetic thermodynamic data were estimated by using commonly integral equations of Horowitz-Metzger (HM) and Coats-Redfern (CR). In vitro the antimicrobial activity of both free L1 and L2 ligands in comparable with their metal complexes were evaluated. This study was strengthen by molecular docking against three protein receptors, which attributing to selected organisms already used in vitro study.

A Ru(II)-p-cymene compound bearing naproxen-pyridineamide. Synthesis, spectroscopic studies, computational analysis and in vitro anticancer activity against lung cells compared to Ru(II)-p-cymene-naproxen and the corresponding drug ligands

The design of new Ru(II) organometallics is a subject of interest to the field of anticancer metallodrugs. This work reports the interaction of the Ru(II)-η6-p-cymene framework with naproxen-pyridineamide (Npxpya, L1), a structurally modified form of the naproxen (HNpx, HL2) drug, to give the new organometallic [Ru(η6-p-cymene)(L1)Cl2] (1) bearing the Npxpya ligand. The reported naproxenate-derived, [Ru(η6-p-cymene)(L2)Cl] (2), is re-prepared, also from the precursor [Ru(η6-p-cymene)Cl2]2(3), and additional investigation is performed. The two Ru(II)-arenes and the L1 ligand are fully characterized by ESI-MS, NMR, ATR/FT-IR and UV/VIS, and their structures corroborated by DFT computational calculations. Time-dependent 1H MNR studies show that both Ru(II)-arenes, despite being stable in non-coordinating solvents, undergo distinct step dissociation in dimethylsulfoxide solvent to give the corresponding drug ligands and [Ru(η6-p-cymene)(dmso)Cl2] (4) species. Electronic absorption spectroscopy experimental data show good correlation with DFT calculations. Organometallics 1 and 2, as well as their corresponding parent drug ligands, exhibit luminescence properties mainly associated to the naproxen moiety. Screening in NCI-H460 and A549 lung cancer cells reveals lack of activity for 2 and L2, while the new organometallic 1 is found to inhibit cell proliferation of both types of cell lines in similar way to the L1 drug. The structural modification, by inserting the pyridineamide moiety into the original structure of naproxen to form the Npxpya conjugated drug, is shown to be crucial for the anticancer activity. Compound 1, despite having IC50 close to the IC50 of L1, does not show significant effect on the mitochondrial membrane potential (MMP), in contrast to the behavior of the free L1 parent drug which significantly decreases the MMP in NCI-H460 cells. Interestingly, since 1H MNR studies indicate that organometallic 1 is completely dissociated in dmso (the solvent used to prepare the drug solutions for cell treatment in the biological assays) to give the L1 free drug and species 4, it is plausible to infer that the presence of Npxpya-free Ru species, probably in the form of species 4, might play a role in inhibiting the mechanism related to the mitochondrial function when the cells are treated with 1, in comparison with the cell treatment with the L1 free drug.

Effects of substituent groups on the crystal structures and luminescence properties of zero-/two-dimensional Zn(II) complexes

The 3-position substituted imidazo[1,2-a]pyridine ligands L1 and HL2 were facilely synthesized, and used for construction of two novel luminescent Zn(II) complexes, namely [ZnCl2(L1)2] (1) and [Zn(L2)2]n (2). Single-crystal X-ray diffraction analysis shows that 1 is zero-dimensional structure, whereas, 2 possesses two-dimensional polymeric network with rhombic grid motifs. The structural differences between 1 and 2 should be determined by the different substituent groups adjacent to carbonyl groups of the 3-position substituted imidazo[1,2-a]pyridine ligands. Complex 1 reveals the red-shifted emission band, compared to free L1 ligand, whereas, 2 displays similar emission spectrum to free HL2 ligand. Such results are also ascribed to substituent group effects and corresponding structural differences.

Syntheses, crystal structures and antibacterial activities of two new Mn(II) complexes based on triaryltriazoles

Two new Mn(II) complexes, trans-[Mn(L1-L2)2(NCS)2] (1–2) with triaryltriazole (1, L1 = 3-(p-bromophenyl)-4-phenyl-5-(2-pyridyl)-1,2,4-triazole; 2, L2 = 3,4-bis(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole), have been synthesized and structurally characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray crystallography. Crystallographic studies revealed that both 1 and 2 contain a distorted octahedral [MnN6] core with two trans-disposed NCS− ions. The L1 ligand, 1 and 2, together with four known homologous Mn(II) complexes, trans-[Mn(L3-L6)2(NCS)2] (3–6) (3, L3 = 3-(p-methoxyphenyl)-4-(p-chlorophenyl)-5-(2-pyridyl)-1,2,4-triazole; 4, L4 = 3-(p-methoxyphenyl)-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole; 5, L5 = 3-(p-chlorophenyl)-4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole; 6, L6 = 3,5-bis(2-pyridyl)-4-(p-methylphenyl)-1,2,4-triazole), were tested in vitro for their antibacterial activities against two Gram-positive bacterial strains and two Gram-negative bacterial strains by the MTT method. The results indicate that 1 exhibited better activity than Penicillin and Kanamycin against Pseudomonas aeruginosa and also better than its free L1 ligand.

A Bifunctional Thioether Linked Coumarin Appended Calix[4]arene Acquires Selectivity Toward Cu(2+) Sensing on Going from Solution to SAM on Gold.

A bifunctional calix[4]arene molecule bearing coumarin moiety on the lower rim and thioether moiety on the upper rim (L1), has been synthesized and well characterized by (1)H, (13)C NMR and mass spectrometry. Suitably functionalized coumarin moieties are well suited for selective recognition of various cations and anions. Among the 10 different metal ions studied, only Cu(2+) and Fe(3+) exhibit appreciable changes in the absorption spectra owing to the availability of functional moieties present at both the lower as well as the upper rim of free L1 in acetonitrile solution. To bring better selectivity, we blocked one of these functional moieties by coating on to a surface so that only the other one is exposed to the environment for sensing. Such a study carried out in the present case using the self-assembled monolayer (SAM) of L1 on Au(111) resulted in selective sensing of Cu(2+) over several other metal ions as studied by surface plasmon resonance (SPR). The SAM of L1 on Au(111) was confirmed by different techniques, such as grazing incidence FT-IR, contact angle measurement, cyclic voltammetry and scanning tunneling microscopy. Thus, L1 is proven to be a suitable sensor for Cu(2+) when attached to gold surface.

Human Papillomavirus 16 L1 Protein Expression and Self-Assembly in Recombinant Pichia pastoris

Human papillomavirus virus-like particles (HPV VLPs) have been shown to be effective in preventing cervical cancer when used as a prophylactic vaccine. However, little attention has been paid to the process of L1 expression and self-assembly of VLPs in vivo. In this study, the methanol concentration is optimized during fermentation to optimize L1 expression and self-assembly into VLPs. HPV 16 L1 was expressed in Pichia pastoris GS115, and successfully self-assembled into HPV 16 VLPs. The results demonstrate that there is a strong correlation between methanol concentration and the expression of HPV L1 as well as VLP formation. During the methanol induction phase, low concentrations of residual methanol (0.1-0.3%) promoted the expression of free L1 and increased the total content of L1, whereas a higher residual methanol concentration (0.32-0.6%) was conducive for the self-assembly of LI into VLPs. To conclude, if the residual methanol concentration is too low or too high, the levels of L1 can easily decrease during the fermentation process.

Hydrothermal Synthesis and Characterization of a Novel 2D Luminescent Silver(I) Microporous Framework with 4‐(4‐Aminobenzene)‐1, 2, 4‐triazole using Tetranuclear Silver(I) Clusters as Secondary Building Blocks

AbstractThe two‐dimensional (2D) cluster‐based silver(I) complex {[Ag2(μ3‐L1)2(μ2‐HL1)]·H2O·3NO3}n (1) was isolated under hydrothermal conditions using the multi‐dentate triazole derivative ligand 4‐(4‐aminobenzene)‐1, 2, 4‐triazole (L1) and the corresponding silver(I) salts. The results indicate that 1 is constructed by tetranuclear AgI clusters as secondary building blocks. Each tetranuclear AgI cluster links four neighboring AgI clusters by eight bridging μ3‐L1 ligands forming a two‐dimensional (2D) microporous cluster‐based framework. Compound 1 also represents a scarcely reported example of coordination frameworks with 4‐(4‐aminobenzene)‐1, 2, 4‐triazole. The solid‐state fluorescence spectrum of 1 exhibits strong red‐shifted enhanced photoluminescence emission in comparison with that of free L1. The versatile bidentate and tridentate coordination modes of L1 in 1 together with flexible dihedral angles between aromatic benzene and triazole rings also reveal great potential in the construction of functional frameworks with L1.

2,2′-Bipyridine Zn(ii) complexes: effect of the 4,4′ substituents on the crystalline solid state properties

The syntheses, structures and photophysical characterizations of new tris-chelated Zn(II) ionic complexes based on substituted bipyridine ligands (L1 = 4,4′-bis(hydroxymethyl)-2,2′-bipyridine; L2 = 4,4′-bis(methoxy)-2,2′-bipyridine) are reported. Owing to the different hydrogen bonding ability and steric hindrance of the 4,4′-bipyridine substituent groups, the L1 and L2 ligands cause a substantial difference in terms of stoichiometry, supramolecular organizations and solid state photophysical properties of the final products. The reaction performed in solution between the Zn(CH3COO)2 salt and the ligand L2 in a 1:3.5 metal-to-ligand stoichiometric ratio afforded the expected octahedral complex [Zn(L2)3](PF6)22 as white crystalline powder. Conversely, the species {[Zn(L1)3](PF6)2}2·L1·2H2O (1a) in the form of pink single crystals is the exclusive product of the reaction performed under the same conditions as those for complex 2 by using L1, the compound including un-coordinated ligands into the crystalline framework. The resulting molecular structure of the new product 1a consists of a sort of supramolecular tetra-cationic adduct, the intercalation of the un-coordinated L1 ligand between two crystallographically equivalent [Zn(L1)3]2+ cations being mainly supported by stacking interactions and cooperative hydrogen bonds. Additionally, compound {[Zn(L2)3](PF6)2}2·L1·2H2O (2a) has also been prepared through targeted synthetic approaches by combining complex 2 with the free L1 ligand. In particular, the liquid-assisted grinding (LAG) method has been successfully applied by mixing complex 2 with a twofold molar amount of L1.

Micro-environmental conditions modulate protein secretion and infectivity of the Trichinella spiralis L1 larva

After digestion of infected meat the free L1 of Trichinella spp. penetrate the intestinal mucosa where they moult to the mature adult stage. We have used proteomics to identify changes in protein secretion during in vitro culture of free T. spiralis muscle larvae under different environmental conditions, and to correlate these changes with their infectivity in mice. Muscle larvae were cultured in different media (RPMI-1640, C-199 and HBSS) under conditions of anaerobiosis, microaerobiosis and in 5% CO2 at 37°C. Following incubation the larval excretory/secretory proteins were analysed by two-dimensional gel electrophoresis and the larvae were used to orally infect naïve CD1 mice. For all culture media tested, infectivity of the L1 was preserved following incubation in anaerobic conditions. In contrast, the infectivity of worms cultured in nutrient-rich media was almost completely abolished in both microaerobiosis and in the presence of 5% CO2. Some infectivity was retained in poor or reduced culture media. Comparative analysis of larval infectivity and protein secretion showed that loss of infectivity correlated with the appearance of non-tyvelosylated proteins that in turn may be related to the onset of moulting.

Synthesis and Spectroscopic Properties of Platinum(II) Terpyridine Complexes Having an Arylborane Charge Transfer Unit

Synthesis, redox, spectroscopic, and photophysical properties of a new class of Pt(II) complexes of the type [PtLnCl]+ are reported, where Ln is 4'-phenyl(dimesitylboryl)-2,2':6',2"-terpyridine (L1) or 4'-duryl(dimesitylboryl)-2,2':6',2"-terpyridine (L2). The free L1 or L2 ligand in CH3CN shows the absorption band responsible for intramolecular charge transfer (CT) from the pi-orbital of the aryl group in L1 or L2 (pi(aryl)) to the vacant p-orbital on the boron atom (p(B)), in addition to pipi* absorption in the 2,2':6',2"-terpyridine (tpy) unit. In particular, the L1 ligand shows an intense CT absorption band as compared with L2. Such intramolecular pi(aryl)-p(B) CT interactions in L1 give rise to large influences on the redox, spectroscopic, and photophysical properties of [PtL1Cl]+. In practice, [PtL1Cl]+ shows strong room-temperature emission in CHCl3 with the quantum yield and lifetime of 0.011 and 0.6 micros, respectively, which has been explained by synergetic effects of Pt(II)-to-L1 MLCT and pi(aryl)-p(B) CT interactions on the electronic structures of the complex. In the case of [PtL2Cl]+, the dihedral angle between the planes produced by the tpy and duryl(dimesitylborane) groups is very large (84 degrees ) as compared with that between the tpy and phenyl(dimesitylborane) units in [PtL1Cl]+ (26-39 degrees ), which disturbs electron communication between the Pt(II)-tpy and arylborane units in [PtL2Cl]+. Thus, [PtL2Cl]+ is nonemissive at room temperature. The important roles of the synergetic CT interactions in the excited-state properties of the [PtL1Cl]+ complex are shown clearly by emission quenching of the complex by a fluoride ion. The X-ray crystal structure of [PtL1Cl]+ is also reported.

New Inorganic−Organic Hybrid Supramolecular Architectures Generated from 2,5-Bis(3-pyridyl)-3,4-diaza-2,4-hexadiene

Two new metal coordination polymers with interesting supramolecular architectures, [Mn(H2O)4(L1)]n(ClO4)2n·2nL1 (1) and [Ag(L1)(NO3)]n (2) [L1 = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene], have been synthesized and characterized structurally. Complex 1 exhibits a novel supramolecular layer architecture sustained by the concurrence of coordination bonds, hydrogen bonds, and π−π stacking interactions: the Mn(II) ions are coordinated by water molecules and the bridging μ2-L1 ligands to yield one-dimensional (1D) zigzag [Mn(H2O)4(L1)]n coordination chains; the free L1 ligands are hydrogen bonded to half of the coordinated water molecules and form π−π stacking triads with the bridging ligands, generating three-strand supramolecular ribbons; and the perchlorate ions form hydrogen bonds with the remaining coordinated water molecules, interlinking the ribbons into an unusual triple-decked supramolecular layer. In complex 2, each Ag(I) ion is tetracoordinated by two μ2-L1 and two μ2-nitrate ligands. The μ2-L1 li...

Immunohistological studies on macrophages in lymph nodes of onchocerciasis patients after treatment with ivermectin.

The role of macrophages in the killing and elimination of microfilariae (mf) was studied immunohistologically in 14 lymph nodes from 10 patients with generalized onchocerciasis 20-68 h after treatment with a single oral dose of 150 microg/kg ivermectin. Mf with signs of damage at light microscopical level were surrounded by a cellular infiltrate comprising macrophages, eosinophils and neutrophils, whereas light microscopically intact mf mostly showed no cellular reaction. Resident mature macrophages expressing the CD 68 epitope usually neither migrated nor attached to damaged mf, especially on the first and second day after ivermectin treatment. However, many young invading macrophages labelled for the L1 protein (antibodies 27 E 10, MAC 387, S 36.48 and 8.5C2) were found within the cellular infiltrate around damaged mf and in adherence to the mf in all lymph nodes after ivermectin treatment. Free L1 protein was observed on the cuticle of the mf. The attacking macrophages contained increased amounts of the enzymes lysozyme, alpha-1-antichymotrypsin and alpha-1-antitrypsin compared to resident macrophages. Free enzymes were found on the cuticle of the mf and around them, indicating a role of these enzymes in the inflammatory reaction to the parasites. The attacking macrophages were strongly labelled for human HLA-DR and they showed further an increased expression of the complement receptors CR1 (CD 35) for C3b and CR3 (CD 11b) for C3 bi in comparison to resident macrophages and thus were considered as activated macrophages. Rarely fragments of mf were seen within multinuclear macrophages. We conclude that young activated macrophages play a major role in the elimination of mf transported to the regional lymph nodes after ivermectin treatment. The immunohistological findings are in accordance with the assumption that these activated macrophages together with granulocytes contribute to the killing of the damaged mf. They also help to limit the damage of the host tissue by release of alpha-1-antichymotrypsin and alpha-1-antitrypsin.

Thermodynamic consideration of the tetragonal lattice distortion of the L1 0 ordered phase

In an attempt to understand the thermodynamic consequences of the tetragonal distortion accompanying the L1 0 ordering, we have conducted a theoretical investigation by treating the problem of a rigid lattice free energy model. The problem is treated as an elasticity problem and a generalized formulation is proposed in a form which can be directly utilized to study incoherent two phase equilibria. By use of the Static Concentration Wave (SCW) mean field model as a rigid lattice free energy model, the formulation is applied to the case of our interest. We show that the thermodynamic stability of the L1 0 phase may be significantly influenced by the tetragonal lattice distortion, depending on the magnitude of the associated strain energy relative to the competing positive entropic contribution in the free energy of the stress free L1 0 phase. In association with this, we suggest that the neglect of tetragonal distortion (i.e. the use of a rigid lattice free energy model) could be a source of serious errors particularly for alloys with lower L1 0 ordering transition temperatures (e.g. CuAu and InMg). A prototype phase diagram of the 〈001〉 f.c.c. ∗ special point structures, calculated with the tetragonal distortion taken into account, has indeed displayed topological features which are fundamentally different from those of a rigid lattice phase diagram and, furthermore, has reproduced the main topological features of the AuCuAu 3Cu and the InMgIn 3Mg sides of their respective phase diagrams.

The accumulation of mature RNA for the Xenopus laevis ribosomal protein L1 is controlled at the level of splicing and turnover of the precursor RNA.

A specific control regulates, at the level of RNA splicing, the expression of the L1 ribosomal protein gene in Xenopus laevis. Under particular conditions, which can be summarized as an excess of free L1 protein, a precursor RNA which still contains two of the nine introns of the L1 gene accumulates. In addition to the splicing block the two intron regions undergo specific endonucleolytic cleavages which produce abortive truncated molecules. The accumulation of mature L1 RNA therefore results from the regulation of the nuclear stability of its precursor RNA. We propose that a block to splicing can permit the attack of specific intron regions by nucleases which destabilize the pre-mRNA in the nucleus. Therefore the efficiency of splicing could indirectly control the stability of the pre-mRNA.