An opioid basis for early-phase isoflurane-induced hypotension in rats

This study was conducted to more clearly delineate the possible role of endogenous opioid receptors and opioid peptides in general anesthesia-associated hypotension in rats. Exposure to 2% isoflurane in oxygen produced a triphasic change in mean arterial pressure (MAP), including an early phase in which MAP fell by -28.4 +/- 2.2%. The magnitude of this early-phase hypotension was attenuated in rats pretreated with intravenous (i.v.) mu-subtype-selective doses of either naloxone or methylnaloxone but not central doses of the selective mu-opioid antagonist beta-funaltrexamine. This early hypotensive phase was also reduced following i.v. pretreatment with antiserum against methionine-enkephalin but not beta-endorphin. These findings suggest that early-phase isoflurane-induced hypotension may be due to activation of peripheral mu-opioid receptors by an endogenous opioid peptide, possibly related to methionine-enkephalin.     

Evaluation of neem seed powder for Fusarium wilt and Meloidogyne control on tomato

Fusarium wilt and root-knot are important diseases of tomato. The use of chemical is becoming less appealing because of the health implications. Also, the chemicals required are often not within the reach of farmers in most of the developing part of the world. This research is aimed at finding an alternative mode of control. Tomato variety Roma VF inoculated with Meloidogyne and Fusarium were treated with 2 g/kg soil neem seed powder in the screenhouse and 2 Mg ha ^{? 1} in the field. An untreated and Furadan treated plot in the field served as control. Neem seed powder significantly reduced the disease severity of Fusarium and root-knot in both screenhouse and field. Results suggest the possible use of neem seed powder for control of the root-knot nematodes - Fusarium wilt disease complex.     

Testing statistical significance scores of sequence comparison methods with structure similarity

Background  

In the past years the Smith-Waterman sequence comparison algorithm has gained popularity due to improved implementations and rapidly increasing computing power. However, the quality and sensitivity of a database search is not only determined by the algorithm but also by the statistical significance testing for an alignment. The e-value is the most commonly used statistical validation method for sequence database searching. The CluSTr database and the Protein World database have been created using an alternative statistical significance test: a Z-score based on Monte-Carlo statistics. Several papers have described the superiority of the Z-score as compared to the e-value, using simulated data. We were interested if this could be validated when applied to existing, evolutionary related protein sequences.     

Identifying dynamical modules from genetic regulatory systems: applications to the segment polarity network

Background  

It is widely accepted that genetic regulatory systems are 'modular', in that the whole system is made up of smaller 'subsystems' corresponding to specific biological functions. Most attempts to identify modules in genetic regulatory systems have relied on the topology of the underlying network. However, it is the temporal activity (dynamics) of genes and proteins that corresponds to biological functions, and hence it is dynamics that we focus on here for identifying subsystems.     

Complexation of a Ligand with a Surfactant Micelle for Soil Heavy Metal Desorption

The ligands iodide (I^?) and thiocyanate (SCN^?), alone or in admixture, in combination with a non-ionic surfactant, Triton X-100, were evaluated as washing agents for heavy metal desorption from a contaminated soil. After seven successive washings, selective sequential extraction (SSE) was performed to determine the heavy metal content that remained associated with each geo-chemical fraction of the soil. The surfactant with 0.336 mol L^?1 of ligand I^? removed 75% Cd and 23% Cu, whereas the mobilization of Zn and Pb were not significant after 7 washings. At a concentration of 0.286 mol L^?1, the ligand SCN^? in the presence of surfactant removed 36% Cd, 44% Cu and 77% Zn. Among the washing agents, the combination of I^? and SCN^? produced the highest desorption efficiencies 95% Cd, 48% Cu, and 3.1% Pb, but not for Zn. The SCN^? ligand extracted the most Zn (77%). The SSE procedure indicated that the I^? removed metals from the exchangeable, carbonate and oxide fractions whereas SCN^? removed metals only from the exchangeable fraction. Both ligands, in the presence of surfactant, removed Cu from all fractions except the exchangeable sites, whereas only SCN^? plus surfactant removed Zn from all fractions. The ligand mixture plus surfactant mobilized only limited quantities of Pb from the oxide and residual fractions.     

Structure-function relationships affecting the insecticidal and miticidal activity of sugar esters

Synthetic sugar esters are a relatively new class of insecticidal compounds that are produced by reacting sugars with fatty acids. The objective of this research was to determine how systematic alterations in sugar or fatty acid components of sugar ester compounds influenced their insecticidal properties. Sucrose octanoate, sorbitol octanoate, sorbitol decanoate, sorbitol caproate, xylitol octanoate, xylitol decanoate and xylitol dodecanoate were synthesized and evaluated against a range of arthropod pests. Dosage-mortality studies were conducted on pear psylla (Cacopsylla pyricola Foerster) on pear, tobacco aphid (Myzus nicotianae) Blackman and tobacco hornworm (Manduca sexta [Johannson]) on tobacco, and twospotted spider mite (Tetranychus urticae Koch) on apple in laboratory bioassays. These sugar esters were compared with insecticidal soap (M-Pede, Dow AgroSciences L.L.C., San Diego, CA), to determine how toxicologically similar these materials were against the arthropod pests. Substitutions in either the sugar or fatty acid component led to significant changes in the physical properties and insecticidal activity of these compounds. The sugar esters varied in their solubility in water and in emulsion stability, yet, droplet spread upon pear leaves occurred at low concentrations of 80-160 ppm and was strongly correlated with psylla mortalities (R2 = 0.73). Sequentially altering the sugar or fatty acid components from lower to higher numbers of carbon chains, or whether the sugar was a monosaccharide or disaccharide did not follow a predictable relationship to insecticidal activity. Intuitively, changing the hydrophile from sorbitol (C6) to xylitol (C5) would require a decrease in lipophile chain length to maintain hydrophilic-lipophilic balance (HLB) relationships, yet an increase in lipophile chain length was unexpectedly needed for increasing insecticidal activity. Thus, the HLB of these materials did not correlate with pear psylla mortalities. Initial insect bioassays and dosage-mortality data found significant differences among sugar ester compounds' toxicity to the range of arthropod species. Sucrose octanoate high in monoester content had the highest activity against the range of arthropod pests at low concentrations of 1200-2400 ppm. No single chemical structure for the xylitol or sorbitol esters were optimally effective against the range of arthropods we tested and sorbitol octanoate and xylitol decanoate had the highest insecticidal activity of this group. All of the sugar ester materials produced high T. urticae mortalities on apple at very low concentrations of 400 ppm. Overall, most of the sugar esters that were examined had superior insecticidal activity compared with insecticidal soap. Sugar ester chemistry offers a unique opportunity to design an insecticide or miticide specific to certain arthropod pests which would be valuable in crop integrated pest management (IPM) programs. Sucrose esters are currently used as additives in the food industry which makes them especially attractive as safe and effective insecticides.