Aqueous photolysis of niclosamide

The photodegradation of [(14)C]niclosamide was studied in sterile, pH 5, 7, and 9 buffered aqueous solutions under artificial sunlight at 25.0 +/- 1.0 degrees C. Photolysis in pH 5 buffer is 4.3 times faster than in pH 9 buffer and 1.5 times faster than in pH 7 buffer. In the dark controls, niclosamide degraded only in the pH 5 buffer. After 360 h of continuous irradiation in pH 9 buffer, the chromatographic pattern of the degradates was the same regardless of which ring contained the radiolabel. An HPLC method was developed that confirmed these degradates to be carbon dioxide and two- and four-carbon aliphatic acids formed by cleavage of both aromatic rings. Carbon dioxide was the major degradate, comprising approximately 40% of the initial radioactivity in the 360 h samples from both labels. The other degradates formed were oxalic acid, maleic acid, glyoxylic acid, and glyoxal. In addition, in the chloronitroaniline-labeled irradiated test solution, 2-chloro-4-nitroaniline was observed and identified after 48 h of irradiation but was not detected thereafter. No other aromatic compounds were isolated or observed in either labeled test system.     

Immunohistochemical study of matrix metalloproteinases‐2 and ‐9, macrophage inflammatory protein‐2 and tissue inhibitors of matrix metalloproteinases‐1 and ‐2 in normal,purulonecrotic and fungal infected equine corneas

Objective Determine the effects of matrix metalloproteinases (MMPs)‐2, ‐9, macrophage inflammatory protein‐2 (MIP‐2), tissue inhibitors of matrix metalloproteinase (TIMP)‐1 and ‐2 by immunohistochemical expression in fungal affected and purulonecrotic corneas. Procedure Paraffin‐embedded equine corneal samples; normal (n = 9), fungal affected (FA; n = 26), and purulonecrotic without fungi (PN; n = 41) were evaluated immunohistochemically for MMP‐2, ‐9, MIP‐2, TIMP‐1 and ‐2. The number of immunoreactive inflammatory cells was counted and statistics analyzed. Western blot was performed to detect MMP‐2, MMP‐9, TIMP‐1 and TIMP‐2 proteins. Results Matrix metalloproteinases‐2, ‐9, MIP‐2, TIMP‐1 and ‐2 immunoreactivity was identified in corneal epithelium of normal corneas, and in corneal epithelium, inflammatory cells, keratocytes, and vascular endothelial cells of both FA and PN samples. Inflammatory cell immunoreactivity was significantly higher in FA and PN samples than in the normal corneas. There was positive correlation between MMP‐2 and MIP‐2, MMP‐9 and MIP‐2, and MMP‐9 and TIMP‐1 in inflammatory cell immunoreactivity in FA samples. There was positive correlation between MMP‐9 and MIP‐2, MMP‐9 and TIMP‐2, MIP‐2 and TIMP‐1, and MIP‐2 and TIMP‐2 in inflammatory cell immunoreactivity in PN samples. Western blot confirmed the presence of all four proteins in equine corneal samples. Conclusion Increased immunoreactivity of MMP‐2 and ‐9 in FA and PN samples is indirectly related to MIP‐2 through its role in neutrophil chemo‐attraction. Tissue inhibitors of matrix metalloproteinase‐1 and TIMP‐2 are up‐regulated in equine purulonecrotic and fungal keratitis secondary to MMP‐2 and MMP‐9 expression. The correlation between MMPs ‐2 and ‐9, MIP‐2, TIMPs ‐1 and ‐2 suggests that these proteins play a specific role in the pathogenesis of equine fungal keratitis.     

A common fold mediates vertebrate defense and bacterial attack

Proteins containing membrane attack complex/perforin (MACPF) domains play important roles in vertebrate immunity, embryonic development, and neural-cell migration. In vertebrates, the ninth component of complement and perforin form oligomeric pores that lyse bacteria and kill virus-infected cells, respectively. However, the mechanism of MACPF function is unknown. We determined the crystal structure of a bacterial MACPF protein, Plu-MACPF from Photorhabdus luminescens, to 2.0 angstrom resolution. The MACPF domain reveals structural similarity with poreforming cholesterol-dependent cytolysins (CDCs) from Gram-positive bacteria. This suggests that lytic MACPF proteins may use a CDC-like mechanism to form pores and disrupt cell membranes. Sequence similarity between bacterial and vertebrate MACPF domains suggests that the fold of the CDCs, a family of proteins important for bacterial pathogenesis, is probably used by vertebrates for defense against infection.     

Selection on heritable phenotypic plasticity in a wild bird population

Theoretical and laboratory research suggests that phenotypic plasticity can evolve under selection. However, evidence for its evolutionary potential from the wild is lacking. We present evidence from a Dutch population of great tits (Parus major) for variation in individual plasticity in the timing of reproduction, and we show that this variation is heritable. Selection favoring highly plastic individuals has intensified over a 32-year period. This temporal trend is concurrent with climate change causing a mismatch between the breeding times of the birds and their caterpillar prey. Continued selection on plasticity can act to alleviate this mismatch.     

Major biocontrol of plant tumors targets tRNA synthetase

Crops can be devastated by pathogenic strains of Agrobacterium tumefaciens that cause crown gall tumors. This devastation can be prevented by the nonpathogenic biocontrol agent A. radiobacter K84, which prevents disease by production of the "Trojan horse" toxin agrocin 84, which is specifically imported into tumorgenic A. tumefaciens strains to cause cell death. We demonstrate that this biocontrol agent targets A. tumefaciens leucyl-tRNA synthetase (LeuRS), an essential enzyme for cell viability, while the agent itself survives by having a second, self-protective copy of the synthetase. In principle, this strategy from nature could be applied to other crop diseases by direct intervention.     

PI3Kgamma is a key regulator of inflammatory responses and cardiovascular homeostasis

Class I phosphoinositide 3-kinase (PI3K) signaling pathways regulate several important cellular functions, including cellular growth, division, survival, and movement. Class IB PI3K (also known as PI3Kgamma) links heterotrimeric GTP-binding protein-coupled receptors to these pathways. Activation of class IB PI3K results in the rapid synthesis of phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P3] and its dephosphorylation product PtdIns(3,4)P2 in the plasma membrane. These two lipid messengers bind to pleckstrin homology domain-containing effectors that regulate a complex signaling web downstream of receptor activation. Characteristic features of this pathway are the regulation of protein kinases and the regulation of small guanosine triphosphatases that control cellular movement, adhesion, contraction, and secretion. Most of the ligands that activate class IB PI3K are involved in coordinating the body's response to injury and infection, and recent studies suggest that small molecule inhibitors of this enzyme may represent a novel class of anti-inflammatory therapeutic agents.