Clofentezine and hexythiazox resistance in Tetranychus urticae Koch in Australia

Clofentezine resistance in T. urticae was first confirmed in Australia in 1987 after Queensland glasshouse roses had been exposed to 40 applications of clofentezine over a 10 month period. Clofentezine resistance in this strain was extremely high (>2.500x) and conferred high level cross-resistance to the chemically unrelated compound hexythiazox. Clofentezine resistance in T. urticae was detected in pome fruit orchards in the Goulburn Valley, Victoria in 1988 and caused field control failure after 5–6 sprays. Resistance was subsequently detected in Adelaide during 1988 and the Bathurst Orange region, NSW in 1989. Clofentezine and hexythiazox resistance appears particularly stable making it difficult to manage.This work contributes in part for the fulfilment of the requirements of the degree of PhD. at the University of Sydney.     

A study on the pretreatment of a sugarcane bagasse sample with dilute sulfuric acid

Experiments based on a 2³ central composite full factorial design were carried out in 200-ml stainless-steel containers to study the pretreatment, with dilute sulfuric acid, of a sugarcane bagasse sample obtained from a local sugar–alcohol mill. The independent variables selected for study were temperature, varied from 112.5°C to 157.5°C, residence time, varied from 5.0 to 35.0 min, and sulfuric acid concentration, varied from 0.0% to 3.0% (w/v). Bagasse loading of 15% (w/w) was used in all experiments. Statistical analysis of the experimental results showed that all three independent variables significantly influenced the response variables, namely the bagasse solubilization, efficiency of xylose recovery in the hemicellulosic hydrolysate, efficiency of cellulose enzymatic saccharification, and percentages of cellulose, hemicellulose, and lignin in the pretreated solids. Temperature was the factor that influenced the response variables the most, followed by acid concentration and residence time, in that order. Although harsher pretreatment conditions promoted almost complete removal of the hemicellulosic fraction, the amount of xylose recovered in the hemicellulosic hydrolysate did not exceed 61.8% of the maximum theoretical value. Cellulose enzymatic saccharification was favored by more efficient removal of hemicellulose during the pretreatment. However, detoxification of the hemicellulosic hydrolysate was necessary for better bioconversion of the sugars to ethanol.     

NMDA Receptor Antagonist Ketamine Impairs Feature Integration in Visual Perception

Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans.     

The cytolytic isolation of the cortex of the sea urchin egg

When the vitelline layer of sea urchin eggs (Lytechinus pictus) is disrupted by trypsin or dithiothreitol and the eggs are placed in an isosmotic medium devoid of Ca²⁺, cytolysis of the eggs occurs. During lysis the entire egg cortex peels off in one piece. Lysis is temperature and pH dependent and is inhibited by cytochalasin B. Cortices from unfertilized eggs contain seven major macromolecular components. A 42K-dalton component is believed to be actin, representing between 12 and 27% of the total protein. Cortices from fertilized eggs may contain between 50 and 65% actin. The actin appears to increase the strength of its attachment to the cortex after fertilization. This method of isolating the entire cortex may be useful for studying structural and enzymatic changes which may occur in the cortex during the cell cycle.     

VH restriction among human cold agglutinins. The VH4-21 gene segment is required to encode anti-I and anti-i specificities.

We previously reported that human autoantibodies with cold agglutinin activity contained a single human VH gene segment (VH4-21) which was also responsible for the cross-idiotypic specificity characteristic of the cold agglutinin response. To confirm and extend this observation we have analyzed at the nucleotide level the H and L chains of six new cold agglutinin molecules derived from different patients. We found that regardless of whether the antibody recognizes the i or the I red cell Ag, restriction at the VH gene segment level is absolute. We also found that even in the absence of somatic mutation the VH4-21 gene segment can encode both anti-i and anti-I specificities. Finally, although the VH4-21 gene segment is essential for cold agglutinin activity, the other genetic elements that contribute to the V region of the antibody molecules can be extremely diverse. The structural information provided in this report sharply restricts the requirement for encoding pathogenic cold agglutinin activity to one of the components of the H chain V region, specifically the VH gene segment. The implications of this apparently absolute requirement for a single VH gene segment, unprecedented in the human autoimmune response, are discussed.     

Forensic visualization of foreign matter in human tissue by near-infrared spectral imaging: methodology and data mining strategies.

BACKGROUND: Rapidity of data acquisition, high image fidelity and large field of view are of tremendous value when looking for chemical contaminants or for the proverbial "needle in the haystack" - in this case foreign inclusions in histologic sections of biopsy or autopsy tissues. Near infrared chemical imaging is one of three chemical imaging techniques (NIR, MIR and Raman) based on vibrational spectroscopy, and provides distinct technical advantages for this application. METHODS: We have chosen to utilize and evaluate near infrared (NIR) imaging for studies of foreign materials in tissue because the experimental configuration is relatively simple, data collection is rapid, and large sample areas can be screened with high image fidelity and spatial resolution. RESULTS: We have shown that NIR imaging can readily find and identify silicone gel inclusions in biological tissue samples. Additionally, preliminary results indicate that spectral signatures in the data set are also potentially sensitive to structural changes in the surrounding tissue that may be induced by the foreign body. CONCLUSIONS: NIR chemical imaging is a powerful, non-destructive tool for localization and identifying foreign contaminants in biological tissue. Preliminary results indicate that NIR imaging is also sensitive enough to differentiate tissue types (perhaps based on collagen structural differences), and provide data on the spatial localization of these components.     

Pyridyl amides as potent inhibitors of T-type calcium channels

A novel series of amide T-type calcium channel antagonists were prepared and evaluated using in vitro and in vivo assays. Optimization of the screening hit 3 led to identification of the potent and selective T-type antagonist 37 that displayed in vivo efficacy in rodent models of epilepsy and sleep.