Superoxide Scavenging Activity of Spin-Labeled Nitrosourea and Triazene Derivatives

Superoxide scavenging activities (SSA) of newly synthesized spin-labeled nitrosourea and triazene derivatives, and their precursor nitroxides were investigated by the ESR/spin-trapping method using the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and hypoxanthine/xanthine oxidase as the superoxide-generating system. The spin-labeled nitrosoureas, triazenes and their precursor nitroxides exhibited excellent SSA, whereas clinically used nitrosourea and triazene, which do not contain the nitroxide moiety, did not show any SSA. Furthermore, it was deduced that these nitroxides scavenge superoxide by redox cycling between nitroxide and corresponding hydroxylamine.     

Late‐life time‐restricted feeding and exercise differentially alter healthspan in obesity

Aging and obesity increase multimorbidity and disability risk, and determining interventions for reversing healthspan decline is a critical public health priority. Exercise and time‐restricted feeding (TRF) benefit multiple health parameters when initiated in early life, but their efficacy and safety when initiated at older ages are uncertain. Here, we tested the effects of exercise versus TRF in diet‐induced obese, aged mice from 20 to 24 months of age. We characterized healthspan across key domains: body composition, physical, metabolic, and cardiovascular function, activity of daily living (ADL) behavior, and pathology. We demonstrate that both exercise and TRF improved aspects of body composition. Exercise uniquely benefited physical function, and TRF uniquely benefited metabolism, ADL behavior, and circulating indicators of liver pathology. No adverse outcomes were observed in exercised mice, but in contrast, lean mass and cardiovascular maladaptations were observed following TRF. Through a composite index of benefits and risks, we conclude the net healthspan benefits afforded by exercise are more favorable than those of TRF. Extrapolating to obese older adults, exercise is a safe and effective option for healthspan improvement, but additional comprehensive studies are warranted before recommending TRF.     

Conformational states of the Rapana thomasiana hemocyanin and its substructures studied by dynamic light scattering and time-resolved fluorescence spectroscopy

Hemocyanins are dioxygen-transporting proteins freely dissolved in the hemolymph of mollusks and arthropods. Dynamic light scattering and time-resolved fluorescence measurements show that the oxygenated and apo-forms of the Rapana thomasiana hemocyanin, its structural subunits RtH1 and RtH2, and those of the functional unit RtH2e, exist in different conformations. The oxygenated respiratory proteins are less compact and more asymmetric than the respective apo-forms. Different conformational states were also observed for the R. thomasiana hemocyanin in the absence and presence of an allosteric regulator. The results are in agreement with a molecular mechanism for cooperative dioxygen binding in molluscan hemocyanins including transfer of conformational changes from one functional unit to another.     

Fluorescence properties and conformational stability of the beta-hemocyanin of Helix pomatia

The beta-hemocyanin (beta-HpH) is one of the three dioxygen-binding proteins found freely dissolved in the hemolymph of the gastropodan mollusc Helix pomatia. The didecameric molecule (molecular mass 9 MDa) is built up of only one type of subunits. The fluorescence properties of the oxygenated and apo-form (copper-deprived) of the didecamer and its subunits were characterized. Upon excitation of the hemocyanins at 295 or 280 nm, tryptophyl residues buried in the hydrophobic interior of the protein determine the fluorescence emission. This is confirmed by quenching experiments with acrylamide, cesium chloride and potassium iodide. The copper-dioxygen system at the binuclear active site quenches the tryptophan emission of the oxy-beta-HpH. The removal of this system increases the fluorescence quantum yield and causes structural rearrangement of the microenvironment of the emitting tryptophyl residues in the apo-form. Time-resolved fluorescence measurements show that the oxygenated and copper-deprived forms of the beta-HpH and its subunits exist in different conformations. The thermal stability of the oxy- and apo-beta-HpH is characterized by a transition temperature (Tm) of 84 degrees C and 63 degrees C, respectively, obtained by differential scanning calorimetry. Increase of the temperature influences the active site at lower temperatures than the environments of tryptophans and tyrosines causing a loss of oxygen bound to the copper atoms. This process is, at least partially, reversible as after cooling of the protein samples, around 60% reinstatement of the copper-peroxide band has been observed. The results confirm the role of the copper-dioxygen complex for the stabilization of the hemocyanin structure in solution. The other important stabilizing factor is oligomerization of the hemocyanin molecule.     

Early diagnosis of invasive pulmonary aspergillosis in a young immunocompetent patient

A 22-year-old insulin-dependent diabetic male was admitted for diabetic ketoacidosis. He developed hospital-acquired pneumonia (HAP) for which empirical antibiotic and antifungal therapy was started on the ward. On day 6, clinical and laboratory findings worsened, and bronchoalveolar lavage (BAL) was performed. Serum real time-polymerase chain reaction (RT-PCR) indicated invasive pulmonary aspergillosis (IPA) and led to antifungal therapy being initiated 48 hours before the results of the BAL culture were available. Despite early appropriate antifungal therapy, however, the patient died on day 22 while being supported by venovenous extracorporeal membrane oxygenation.     

Intercellular chitinase and peroxidase activities associated with resistance conferred by geneLr35to leaf rust of wheat

The effect of leaf rust (Puccinia triticina) infection on intercellular chitinase (EC 3.2.1.14) and peroxidase (EC 1.11.1.7) activities was studied in resistant [RL 6082 (Thatcher/Lr35)] and susceptible (Thatcher) near isogenic wheat (Triticum aestivum L.) lines at seedling, stem elongation and flag leaf stages of plant growth. The levels of activity of these enzymes were low during the seedling and stem elongation stages. Resistant plants at the flag leaf stage, during which the Lr35 resistance gene was maximally expressed, exhibited high constitutive levels of chitinase and peroxidase activities, in contrast to the lower constitutive levels of susceptible plants. The results suggest that chitinase and peroxidase, constitutively present in the intercellular spaces of Thatcher/Lr35 wheat leaves, may play a role in Lr35 mediated resistance to leaf rust.     

Intercellular proteins and β-1,3-glucanase activity associated with leaf rust resistance in wheat

To investigate biochemical aspects of resistance conferred by the Lr35 gene for adult-plant resistance in wheat ( Triticum aestivum L.) to leaf rust, pathogen development was related to intercellular protein composition and β -1,3-glucanase (EC 3.2.1.39) activities at three growth stages in infected and uninfected resistant (RL6082 [Thatcher/ Lr35 ]) and susceptible (Thatcher) plants. Leaf rust symptoms produced by pathotype UVPrt9 of Puccinia recondita f. sp. tritici showed that resistance conferred by Lr35 was most effective at the flag leaf stage. Furthermore, fluorescence microscopy indicated that resistance was strongly associated with hypersensitive cell death of invaded tissue. According to polypeptide profiles, intercellular proteins with molecular masses of 35, 33, 31 and 26 kDa were constitutively present at higher levels in resistant than in susceptible plants at the flag leaf stage. Four intercellular proteins (35, 33, 32 and 31 kDa) serologically related to β -1,3-glucanase were present in resistant and susceptible genotypes during all stages of plant growth. Resistance was associated with high constitutive levels of β -1,3-glucanase activity. Susceptibility on the other hand was associated with low constitutive levels of β -1,3-glucanase, while high levels were induced by infection during more advanced stages of colonization. Our results suggest that β -1,3-glucanase is involved in the defense response controlled by the Lr35 gene.     

Coordination of (aminoalkyloxymethyl)dimethylphosphine oxides with palladium(II). Crystal structure of trans-bis[2-(dimethylphosphinoylmethoxy-1,1-dimethylethylamine)]palladium(II) dichloride

The synthesis, structure and spectroscopic properties of novel palladium(II) chloro complexes with a series of (aminoalkyloxymethyl)dimethylphosphine oxides (AOPO) are reported. The complexes with general formula PdCl₂(N,N′-AOPO₂) were obtained by the reaction of PdCl₂(CH₃CN)₂ with the ligands in dry ethanol. The crystal structure of the trans-bis[2-(dimethylphosphinoylmethoxy-1,1-dimethylethylamine)]palladium(II) dichloride has been determined from single-crystal X-ray diffraction data. The compound crystallizes in monoclinic crystal system with P2₁/n space group. The square-planar coordination sphere of palladium consists of two N atoms from two aminoalkyldimethylphosphine ligands and two Cl atoms in trans-arrangement. The AOPO ligand has monodentate coordination through the NH₂ group. The Pd-N and Pd-Cl distances are 2.0610(14) and 2.3225(4) Å, respectively. The preparation of complexes with a composition PdCl₂(AOPO)₂ in chloroform solution are also reported.