Bone mass toxicity associated with inhalation exposure to toluene

The inhalation of a wide range of organic solvents has become popular among young adults. Toluene is one of the most commonly used solvents in industry; it is easily available and conventient to use. Many toxicologic effects on biological systems secondary to deliberate inhalation of toluene have been reported, but investigations on adverse effects associated with bone morbidity is limited. The purpose of this study is to determine bone mineralization and investigate the adverse effects of toluene on bone. The bone mineral density and content of the femoral neck of mice exposed to toluene at 300 ppm for 8 wk were measured by dual X-ray absorptiometry and found significantly reduced compared to the control group. Chronic exposure to toluene was found to affect bone metabolism, and toluene-induced changes could contribute to bone resorption and inhibition of bone formation. Toluene seems to be the responsible component for the demineralizating effects of commonly abused substances, and medical doctors must promote their education about the health hazards in those who abuse solvents especially in areas where inhalant abuse is endemic.     

Synthesis and biological evaluation of 6,7-disubstituted 4-aminopyrido[2,3-d]pyrimidines as adenosine kinase inhibitors

The synthesis and structure-activity relationship of a series of 6,7-disubstituted 4-aminopyrido[2,3-d]pyrimidines as novel non-nucleoside adenosine kinase inhibitors is described. A variety of substituents, primarily aryl, at the C6 and C7 positions of the pyridopyrimidine core were found to yield analogues that are potent inhibitors of adenosine kinase. In contrast to the 5,7-disubstituted and 5,6,7-trisubstituted pyridopyrimidine series, these analogues exhibited only modest potency to inhibit AK in intact cells.     

Protective and therapeutic capacity of human single-chain Fv-Fc fusion proteins against West Nile virus

West Nile virus has spread rapidly across the United States, and there is currently no approved human vaccine or therapy to prevent or treat disease. Passive immunization with antibodies against the envelope protein represents a promising means to provide short-term prophylaxis and treatment for West Nile virus infection. In this study, we identified a panel of 11 unique human single-chain variable region antibody fragments (scFvs) that bind the envelope protein of West Nile virus. Selected scFvs were converted to Fc fusion proteins (scFv-Fcs) and were tested in mice for their ability to prevent lethal West Nile virus infection. Five of these scFv-Fcs, 11, 15, 71, 85, and 95, protected 100% of mice from death when given prior to infection with virus. Two of them, 11 and 15, protected 80% of mice when given at days 1 and 4 after infection. In addition, four of the scFv-Fcs cross-neutralized dengue virus, serotype 2. Binding assays using yeast surface display demonstrated that all of our scFvs bind to sites within domains I and II of West Nile virus envelope protein. These recombinant human scFvs are potential candidates for immunoprophylaxis and therapy of flavivirus infections.     

Cyclooxygenase 2 activity modulates the severity of murine Lyme arthritis

Cyclooxygenase (Cox) is a key enzyme in the biosynthetic metabolism of prostaglandins. The inducible isoform of Cox-2 has been implicated in inflammation and its specific inhibition can be used to treat noninfectious inflammatory diseases, such as rheumatoid arthritis. Borrelia burgdorferi, the agent of Lyme disease, can induce joint inflammation. Here we show that B. burgdorferi induced the upregulation of cox-2 gene expression in murine joints at the onset of arthritis in infected mice. The level of mRNA expression correlated with the degree of inflammation. The specific inhibition of Cox-2 diminished the degree of joint inflammation, without affecting B. burgdorferi-specific antibody or cytokine responses. Cox-2 activity is therefore associated with the genesis of infectious arthritis caused by B. burgdorferi.     

Coordination topology and stability for the native and binding conformers of chymotrypsin inhibitor 2

We demonstrate that the stabilization of the binding region is accomplished at the expense of a loss in the stability of the rest of the protein. A novel molecular mechanics (MM) approach is introduced to distinguish residue stabilities of proteins in a given conformation. As an example, the relative stabilities of folded chymotrypsin inhibitor 2 (CI2) in unbound form, and CI2 in complex with subtilisin novo is investigated. The conformation of the molecule in the two states is almost identical, with an approximately 0.6-A root-mean-square deviation (RMSD) of the Calpha atoms. On binding, the packing density changes only at the binding loop. However, residue fluctuations in the rest of the protein are greatly altered solely due to those contacts, indicating the effective propagation of perturbation and the presence of remotely controlling residues. To quantify the interplay between packing density, packing order, residue fluctuations, and residue stability, we adopt an MM approach whereby small displacements are inserted at selected residues, followed by energy minimization; the displacement of each residue in response to such perturbations are organized in a perturbation-response matrix L. We define residue stability lambda(i) = summation operator((j)L(ij))/ summation operator((j) L(ji)) as the ratio of the amount of change to which the residue is amenable, to the ability of a given residue to induce change. We then define the free energy associated with residue stability, DeltaG(lambda) = -RT ln lambda. DeltaG(lambda) intrinsically selects the residues that are in the folding core. Upon complexation, the binding loop becomes more resistant to perturbation, in contrast to the alpha-helix that favors change. Although the two forms of CI2 are structurally similar, residue fluctuations differ vastly, and the stability of many residues is altered upon binding. The decrease in entropy introduced by binding is thus compensated by these changes.     

A Proteomic Approach Provides New Insights into the Control of Soil-Borne Plant Pathogens by Bacillus Species

Beneficial microorganisms (also known as biopesticides) are considered to be one of the most promising methods for more rational and safe crop management practices. We used Bacillus strains EU07, QST713 and FZB24, and investigated their inhibitory effect on Fusarium. Bacterial cell cultures, cell-free supernatants and volatiles displayed varying degrees of suppressive effect. Proteomic analysis of secreted proteins from EU07 and FZB24 revealed the presence of lytic enzymes, cellulases, proteases, 1,4-β-glucanase and hydrolases, all of which contribute to degradation of the pathogen cell wall. Further proteomic investigations showed that proteins involved in metabolism, protein folding, protein degradation, translation, recognition and signal transduction cascade play an important role in the control of Fusarium oxysporum. Our findings provide new knowledge on the mechanism of action of Bacillus species and insight into biocontrol mechanisms.     

Optimization and enhanced production of α-amylase and protease by a newly isolated Bacillus licheniformis ZB-05 under solid-state fermentation

Eight different agro-residues were tested for α-amylase and protease production by using Bacillus licheniformis ZB-05. Among them, rice husk (RH) was proved as the best substrate for two enzymes (α-amylase 443 U/g and protease 469,000 U/g). Maximum enzyme production was observed to be 30 % initial moisture, with a growth period of 36 h in 20 and 30 % inoculum volumes for α-amylase and protease, respectively. The best enzyme recovery from solid mass was obtained when extracted with tap water. Among the tested various nitrogen sources, 1 % ammonium sulphate followed by 2 % Bacto liver, 2 % ammonium sulphate and 1 % Bacto casaminoacid served as the best inorganic and organic nitrogen sources for α-amylase and protease production, respectively. As additional carbon sources, 2 % soluble starch enhanced α-amylase production, while 1 % maltose enhanced protease production.