Polyurethane Adhesive Ingestion

Polyurethane adhesives are found in a large number of household products in the United States and are used for a variety of purposes. Several brands of these expanding wood glues (those containing diphenylmethane diisocyanate [MDI]) have the potential to form gastrointestinal (GI) foreign bodies if ingested. The ingested adhesive forms an expanding ball of glue in the esophagus and gastric lumen. This expansion is caused by a polymerization reaction using the heat, water, and gastric acids of the stomach. A firm mass is created that can be 4-8 times its original volume. As little as 2 oz of glue have been reported to develop gastric foreign bodies. The obstructive mass is reported to form within minutes of ingestion of the adhesive. The foreign body can lead to esophageal impaction and obstruction, airway obstruction, gastric outflow obstruction, mucosal hemorrhage, ulceration, laceration, perforation of the esophageal and gastric linings, and death. Clinical signs following ingestion include anorexia, lethargy, vomiting, tachypnea, and abdominal distention and pain, and typically develop within 12 hours. Clinical signs may depend upon the size of the mass. If left untreated, perforation and rupture of the esophagus or stomach can occur. The glue mass does not stick to the GI mucosa and is not always detectable on abdominal palpation. Radiographs are recommended to confirm the presence of the “glue-ball” foreign body, and radiographic evidence of the obstruction may be seen as early as 4-6 hours following ingestion. Emesis is contraindicated owing to the risk of aspiration of the glue into the respiratory tree or the subsequent lodging of the expanding glue mass in the esophagus. Likewise, efforts to dilute the glue and prevent the formation of the foreign body through administration of liquids, activated charcoal, or bulk-forming products to push the foreign body through the GI tract have proven ineffective. Even endoscopy performed to remove the foreign body has been shown to be unreliable. The safest, most effective, and successful therapy is surgical intervention to remove the GI foreign body. If performed early enough, complete recovery of the animal can be expected. Differential diagnoses for polyurethane adhesive ingestion include any potential cause of GI obstruction. The public is largely unaware of the hazards that ingestion of this product may produce. Public education efforts are needed to inform pet owners about the hazards of these glues and the overall importance of providing our companion animals with safe, poison-free environments.     

New developments in insecticide resistance in the glasshouse whitefly (Trialeurodes vaporariorum) and the two-spotted spider mite (Tetranychus urticae) in the UK

A recent survey of insecticide resistance in two of the most problematic pests in UK glasshouses revealed some new developments. At least some individuals in all UK samples of Trialeurodes vaporariorum that were tested resisted the insect growth regulator (IGR) buprofezin. The most strongly resistant strains were unaffected by the field application rate of this compound, and even samples from populations that had never been exposed to buprofezin contained individuals that survived the highest concentration applied (10,000 mg litre-1). The field rate of buprofezin was shown to select for resistance through vapour action alone. The benzophenylurea teflubenzuron, an unrelated IGR, was cross-resisted by buprofezin-resistant individuals. There was no evidence of resistance to imidacloprid, but all T vaporariorum strains tested, regardless of origin, exhibited a high innate tolerance to nicotine, when compared with another whitefly species, Bemisia tabaci. Marked resistance to fenbutatin oxide and tebufenpyrad was found in single glasshouse populations of Tetranychus urticae, but these compounds and abamectin appeared to remain highly effective against all other strains collected.     

Report of resistance to the neonicotinoid insecticide imidacloprid in Trialeurodes vaporariorum (Hemiptera: Aleyrodidae)

Susceptibilities of UK and mainland European samples of Trialeurodes vaporariorum (Westwood) to the neonicotinoid insecticide imidacloprid were investigated over a 7 year period. All 24 strains collected between 1997 and 2003 showed similar baseline levels of susceptibility to that of a known susceptible laboratory strain when exposed to a diagnostic concentration (128 mg L(-1)) of formulated imidacloprid. Two samples collected during 2004, one from the UK and one from The Netherlands, demonstrated reduced susceptibility at this concentration. Using dose-response assays, the presence of resistant individuals was disclosed in both these strains; some individuals were unaffected at doses high enough to induce phytotoxic effects. This report represents the first confirmed cases of neonicotinoid resistance inducing control failures in T. vaporariorum, and highlights a need for careful vigilance to sustain the effectiveness of imidacloprid and related neonicotinoid insecticides.     

Acetyl-CoA Carboxylase—a Graminicide Target Site

Acetyl-CoA carboxylase catalyses the first committed step in fatty acid (and acyl lipid) formation. The enzyme has been shown to exert a high degree of flux control for lipid biosynthesis in leaves and, therefore, it is not surprising that chemicals which can inhibit it effectively are successful herbicides. These chemicals belong mainly to the cyclohexanedione and aryloxyphenoxypropionate classes and are graminicides. The reason for the selectivity of these herbicides towards grasses lies in the nature of the target site, acetyl-CoA carboxylase. Recent advances in our knowledge of acetyl-CoA carboxylases from sensitive and resistant plants has revealed some important facts. Dicotyledons, which are resistant, have a multi-enzyme complex type of carboxylase in their chloroplasts while grasses have a multifunctional protein. Both divisions of plants have two isoforms of the enzyme, the second being in the cytosol. Detailed study of multifunctional forms of acetyl-CoA carboxylases, which have different sensitivities to herbicides, suggests that herbicide resistance is correlated with cooperativity of herbicide binding to the native dimeric form of the carboxylase. © 1997 SCI.     

A thermally re-mendable cross-linked polymeric material

We have developed a transparent organic polymeric material that can repeatedly mend or "re-mend" itself under mild conditions. The material is a tough solid at room temperature and below with mechanical properties equaling those of commercial epoxy resins. At temperatures above 120 degrees C, approximately 30% (as determined by solid-state nuclear magnetic resonance spectroscopy) of "intermonomer" linkages disconnect but then reconnect upon cooling, This process is fully reversible and can be used to restore a fractured part of the polymer multiple times, and it does not require additional ingredients such as a catalyst, additional monomer, or special surface treatment of the fractured interface.     

Cypermethrin inhibits egg development in the ixodid tick, Amblyomma hebraeum

The pyrethroid insecticide, cypermethrin (CyM), stimulates vitellogenesis in Ornithodoros moubata (an argasid tick) by stimulating the release of the normal vitellogenesis-inducing factor (a neuropeptide) and subsequent release of the vitellogenic hormone [19]. Here we examine the effects of CyM on egg development in the ixodid tick, Amblyomma hebraeum. Ovary weight, oocyte size, and vitellin content of the ovary were measured after CyM treatment; in partially fed ticks, none of these parameters were affected significantly. However, CyM treatment caused an inhibition of ovary development, as well as reduction of both hemolymph 20-hydroxyecdysone (20E; the vitellogenic hormone in this species) and vitellogenin (Vg)-concentrations in engorged ticks. In addition, the degree of salivary gland degeneration (which is triggered by 20E) was slightly reduced in CyM-treated engorged ticks. These results indicate that CyM acts differently in Amblyomma compared to Ornithodoros. Instead of stimulating vitellogenesis, CyM inhibits egg development perhaps in part as a result of inhibiting release of 20E.     

Herbicide effect on growth and seed production of Lolium multiflorum in Atlantic Canada

Lolium multiflorum Lam. (annual ryegrass) is used extensively as a forage crop and seed is produced in several areas worldwide. Seed production has been shown to be commercially possible in Atlantic Canada but improved weed control is needed. Studies were conducted in two provinces (Prince Edward Island and New Brunswick) to determine the effects of the herbicides bentazon, bromoxynil/MCPA, dicamba/MCPA, thifensulfuron/tribenuron, 2,4-D and MCPA on weed control, L. multiflorum growth, seed yields and seed germination in 1998 and 1999. The herbicides MCPA, dicamba/MCPA and bromoxynil/MCPA as evaluated in these experiments provided acceptable control of the broad-leaved weeds present and had no effect on seed yield or seed germination. Although the thifensulfuron/tribenuron caused early foliar injury, the plants recovered and it provided excellent weed control. None of the herbicides affected seed germination. MCPA, dicamba/MCPA and bromoxynil/MCPA could be used to provide control of broad-leaved weeds and thifensulfuron/tribenuron could be used if growers were willing to accept some early injury and possible yield loss to obtain the improved weed control.