ABAD directly links Abeta to mitochondrial toxicity in Alzheimer's disease

Mitochondrial dysfunction is a hallmark of beta-amyloid (Abeta)-induced neuronal toxicity in Alzheimer's disease (AD). Here, we demonstrate that Abeta-binding alcohol dehydrogenase (ABAD) is a direct molecular link from Abeta to mitochondrial toxicity. Abeta interacts with ABAD in the mitochondria of AD patients and transgenic mice. The crystal structure of Abeta-bound ABAD shows substantial deformation of the active site that prevents nicotinamide adenine dinucleotide (NAD) binding. An ABAD peptide specifically inhibits ABAD-Abeta interaction and suppresses Abeta-induced apoptosis and free-radical generation in neurons. Transgenic mice overexpressing ABAD in an Abeta-rich environment manifest exaggerated neuronal oxidative stress and impaired memory. These data suggest that the ABAD-Abeta interaction may be a therapeutic target in AD.     

Enzyme-linked immunosorbent assay for the pyrethroid deltamethrin

A competitive enzyme-linked immunosorbent assay (ELISA) for the detection of deltamethrin was developed. Two haptens, cyano[3-(4-aminophenoxy)phenyl]methyl 1R-cis-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropanecarboxylate and 3-[(+/-)-cyano[1R-cis-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropan ecarbonyloxy]methyl]phenoxyacetic acid, were synthesized and conjugated with thyroglobulin as immunogens. Four antisera were generated and screened against six different coating antigens. The assay that was the most sensitive for deltamethrin was optimized and characterized. The I(50) for deltamethrin was 17.5 +/- 3.6 microg/L, and the lower detection limit was 1.1 +/- 0.5 microg/L. This ELISA assay had relatively low cross-reactivities with other major pyrethroids, such as permethrin, phenothrin, bioresmethrin, cyfluthrin, and cypermethrin. Methanol was found to be the best organic cosolvent for this ELISA, with optimal sensitivity observed at a concentration of 40% (v/v). The assay parameters were unchanged at pH values between 5.0 and 8.0, whereas higher ionic strengths strongly suppressed the absorbances. To increase the sensitivity of the overall method, a C(18) sorbent-based solid-phase extraction was used for river water samples. River water samples fortified with deltamethrin were analyzed according to this method. Good recoveries and correlation with spike levels were observed.     

Density and microviscosity studies of palm oil/water emulsions

Electron paramagnetic resonance (EPR) and densitometry were used to measure the temperature- and rate-dependent formation of fat crystals in emulsion droplets in hardened palm kernel oil in water emulsions. The solid fat content in emulsions can be critical for the functionality of the emulsions in a wide variety of applications. Therefore, new and accessible methods are needed to monitor solid fat content in order to control the functional properties of these emulsions. EPR measurements showed that the microviscosity within the oil droplets could be measured as a function of temperature and that the storage temperature below the main fat melting point is crucial for an increase in the microviscosity, due to fat solidification. The microviscosity of the oil droplets could be an important parameter for defining functional performance (e.g., rheology and partial coalescence). Density measurements provided a simple and accurate method for monitoring changes in phase state of the oil. The phase behavior agreed well with the EPR results, demonstrating that accurate density measurements could prove to be a valuable tool for monitoring fat crystallization processes.     

Hapten and antibody production for a sensitive immunoassay determining a human urinary metabolite of the pyrethroid insecticide permethrin

Permethrin is the most popular synthetic pyrethroid insecticide in agriculture and public health. For the development of the enzyme-linked immunosorbent assay (ELISA) to evaluate human exposure to permethrin, the glycine conjugate (DCCA-glycine) of a major metabolite, cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DCCA), of permethrin was established as the target analyte. Four different types of the cis- and trans-isomers of immunizing haptens were synthesized as follows: N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine (hapten 3), N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)-4-amino-l-phenylalanine (hapten 5), N-(N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine)amino-6-(2,4-dinitrophenyl)aminohexanoic acid (hapten 9), and N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine-4-oxobutanoic acid (hapten 24). Sixteen polyclonal antibodies produced against each cis- or trans-hapten-thyroglobulin conjugate as immunogens were screened against numerous hapten-bovine serum albumin conjugates as coating antigens. Six ELISAs with both a heterologous hapten structure and a heterologous hapten configuration (cis/trans or trans/cis) between antibody and coating antigen showed a high sensitivity for the target analyte. The IC50 was 1.3, 2.1, and 2.2 microg/L for the trans-target analyte and 0.4, 2.3, and 2.8 microg/L for the cis-target analyte. The immunizing haptens, except for hapten 5, provided the target specific antibodies. Molecular modeling of the haptens supported the selection of reasonable immunizing haptens that best mimicked the target analyte. Hapten 5 was suitable as a coating antigen rather than as an immunogen since it had a different geometry. Very low cross-reactivities were measured to permethrin, its free metabolite (DCCA), PBA-glycine conjugate, and glycine. The ELISA will be optimized for the detection of total cis/trans-DCCA-glycine in human urine samples.     

The recent decline of a New Zealand endemic: how and why did populations of Archey's frog Leiopelma archeyi crash over 1996-2001?

Dramatic changes have been documented in New Zealand's vertebrate faunas since human settlement, involving major declines and extinctions, but over recent years few species have declined in numbers so rapidly as the terrestrial Archey's frog Leiopelma archeyi (Anura: Leiopelmatidae). Long-term monitoring over more than 20 years revealed a major population reduction of the species over 1996-2001 and L. archeyi is now classified as Nationally Critical under the New Zealand threat classification system. The decline progressed northwards in the Coromandel ranges, and mostly larger (female) frogs survived. On a 100 m² study plot at Tapu Ridge, annual population estimates averaged 433 frogs (SE ±32) over 1984-1994, declining by 88% to average 53 frogs (SE ±8) over 1996-2002. A mean annual survival rate of 82% for most years declined to 33% over 1994-1997. There is mounting evidence to suggest that disease is the major agent of decline, supported by (1) the rapidity and severity of decline, (2) the progressive (south to north) nature of decline, and (3) finding frogs with chytriodiomycosis from Batrachochytrium dendrobatidis at the time of decline. Surprisingly, sympatric populations of the semi-aquatic Leiopelma hochstetteri have not declined dramatically, nor has a western population of L. archeyi at Whareorino, despite chytridiomycosis occurring in some frogs there. Sustaining and restoring populations of L. archeyi in New Zealand raises major challenges for conservation management.     

Behavioural responses of red king crab to crab pots

High bycatch of female and sublegal sized male king crabs in the fishery is of concern to fishermen and management agencies; the efficiency of gear currently used in the fishery needs to be improved. This study examined behavioural responses of red king crabs to pots under laboratory conditions with time-lapse video. Crabs approached the pot from downstream, 82% of searches were confined to within 135 ° of the downstream direction, and 78.3% of crabs searched less than 90 ° before leaving or entering. The probability of entry success increased with the number of approaches. Crabs which failed to enter made an average of 2.6 approaches compared with 3.9 approaches for crabs which entered pots. The entry success rate was 8.1%. No significant differences in approach, search, and entry were found between ovigerous females, juvenile females, legal-sized males, and sublegal-sized males. Legal males (≥ 178 mm carapace width) had a significantly lower escape attempt rate and escape rate than sublegal males and females. Crabs depend on chemical cues during foraging, approaching, and searching. The current king crab pot is inefficient because crabs have difficulties in accessing the entrances and non-legal crabs have difficulties in escaping.     

Qualitative and quantitative strategies of thermal adaptation of grass carp (Ctenopharyngodon idella) cytoplasmic malate dehydrogenases

Malate dehydrogenase isozymes of grass carp,Ctenopharyngodon idella, were identified by mitochondrial preparation and thermal denaturation. The structural and kinetic characteristics of chromatographically separated thermostable and thermolabile cMDHs were different in (1) half-life at 42°C, 10 min and 24 h, respectively, (2) optimal substrate, oxaloacetate and malate, concentrations, and (3) the apparent Michaelis-Menten constants of NADH and oxaloacetate.Total MDH activity in white muscle of 11°C-acclimated fish was about twice that of the 30°C-acclimated group. In addition, the ratio of the thermostable to thermolabile cMDH activity in white muscle of 30°C-acclimated fish was significantly higher than that of 11°C-acclimated fish. These results suggest that temperature acclimation can induce temperature compensation in MDH activity and differential expression of thermostable and thermolabile cMDH isozymes in freshwater fish.     

Determination of pyrethroid residues in agricultural products by an enzyme-linked immunosorbent assay

To determine cypermethrin and permethrin in agricultural products, a competitive enzyme-linked immunosorbent assay (ELISA) method was employed. The matrix interferences were minimized by direct dilution of the extracts. No further cleanup was needed. A minimum matrix effect with a 1:10 dilution of white wine for cypermethrin and a 1:200 dilution of red and white wines, fruits, and vegetables for permethrin was found when phosphate-buffered saline containing 40% methanol was employed as the diluent. Good recoveries of spiked levels were observed. The mean percentage recoveries of cypermethrin spiked in white wine and permethrin spiked in red and white wines were 99.7, 74, and 78%, respectively. The mean percentage recoveries of permethrin spiked in apple, banana, cucumber, lettuce, onion, and peach were 99.2, 105, 70.2, 97.5, 94.4, and 89.4%, respectively. Validation of the ELISA method with permethrin-spiked lettuce and peach was carried out using gas chromatography with mass spectrometry, resulting in a good recovery and correlation.