2-methylisoborneol implicated as a cause of off-flavour in channel catfish, Ictalums punctatus (Rafinesque), from commercial culture ponds in Mississippi

Abstract. Samples of water, sediment and fish were collected from six commercial channel catfish, Ictalurus punctalus (Rafinesque), ponds from May to October and analysed for muddy-odour producing compounds. Three episodes of off-flavour in the fish occurred in late summer. The episodes were of 2–3 months' duration and correlated with the levels of 2-methylisoborneol in water, sediment and fish. Oscillatoria agardliii was the dominant phytoplankton in ponds with off-flavour fish. Other known muddy odour-producing compounds such as geosmin, 2-isopropyl-3-mcthoxypyrazinc, 2-isobutyl-3-methoxypyrazine and 2-isobutyl-6-methoxypyrazinc were not detected in the water sediment or at concentrations greater than 5·0 ng/l.     

MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF PERIPHERAL NERVE SHEATH TUMORS OF THE CANINE BRACHIAL PLEXUS IN 18 DOGS

Magnetic resonance imaging (MRI) examinations from 18 dogs with a histologically confirmed peripheral nerve sheath tumor (PNST) of the brachial plexus were assessed retrospectively. Almost half (8/18) had a diffuse thickening of the brachial plexus nerve(s), six of which extended into the vertebral canal. The other 10/18 dogs had a nodule or mass in the axilla (1.2-338 cm3). Seven of those 10 masses also had diffuse nerve sheath thickening, three of which extended into the vertebral canal. The majority of tumors were hyperintense to muscle on T2-weighted images and isointense on T1-weighted images. Eight of 18 PNSTs had only minimal to mild contrast enhancement and many (13/18) enhanced heterogeneously following gadolinium DTPA administration. Transverse plane images with a large enough field of view (FOV) to include both axillae and the vertebral canal were essential, allowing in-slice comparison to detect lesions by asymmetry of structures. Higher resolution, smaller FOV, multiplanar examination of the cervicothoracic spine was important for appreciating nerve root and foraminal involvement. Short tau inversion recovery, T2-weighted, pre and postcontrast T1-weighted pulse sequences were all useful. Contrast enhancement was critical to detecting subtle diffuse nerve sheath involvement or small isointense nodules, and for accurately identifying the full extent of disease. Some canine brachial plexus tumors can be challenging to detect, requiring a rigorous multiplanar multi-pulse sequence MRI examination.     

IMAGING DIAGNOSIS—METASTATIC ADRENAL PHEOCHROMOCYTOMA IN A DOG

A 10‐year‐old Akita mix became acutely paraplegic. Upon magnetic resonance imaging, multiple, slightly T2‐hyperintense, T1‐isointense extradural masses, relative to spinal cord were found in the vertebral canal. The retroperitoneal masses had mixed T2‐signal intensity. The contrast enhancement pattern for the spinal masses was both homogenous and heterogenous. The diagnosis was metastatic pheochromocytoma. Signal intensity of the tumors in this dog was similar to reports of pheochromocytoma in human beings.     

Complexity of applying minimum legal sizes (MLS) of retention in an indigenous coral reef fishery

Abstract Retaining coral reef fish for subsistence during commercial fishing is a common practice for indigenous fishers in the Torres Strait, Australia, despite being inconsistent with legislation. Fisher access point surveys were completed between 2004 and 2006 on three islands in Torres Strait to characterise this subsistence practice and assess the level to which it undermines current minimum legal fish sizes. Approximately 15% of the annual total catch was retained for subsistence during commercial fishing. Notably, subsistence catch of the most commercially valuable species almost entirely comprised individuals smaller than the minimum legal sizes. The higher proportions of undersized individuals of valuable species retained during commercial fishing on some of the islands were most likely associated with an increase in professionalism of the fishers. These results demonstrate how the intended outcomes from a management strategy can be undermined when the specific operational conditions of the fishery are not considered. Successful implementation of management arrangements in indigenous communities ultimately depends on the sociocultural conditions of the communities and their understanding and adherence to the rules. A productive way forward for the management of this fishery is greater engagement of indigenous communities and managers in co‐management arrangements.     

Eradication of paraquat-resistant Hordeum glaucum Steud. by prevention of seed production for 3 years

Seeds of two biotypes of the grass weed, barley grass (Hordeum glaucum Steud.), one resistant and the other susceptible to the herbicide paraquat, were studied to ascertain whether they had the same dormancy characteristics. Regardless of field storage conditions, both paraquat-resistant and susceptible H. glaucum germinated readily after identical short-term (2-month) innate dormancy. A field experiment conducted to determine the longevity of seeds of resistant H. glaucum in the soil seedbank revealed that, in the absence of fresh seed production, reserves of this species were exhausted within 3 years. These experiments establish that seeds of the resistant biotype of H. glaucum have a short residual life in the seedbank, and that by totally preventing seed production for 3 successive years it is possible to eradicate this resistant biotype. Supression rf'Hordeum glaucum résistant au paraquat par l'empechement de la production de graines pendant 3 ans Les graines de deux biotypes de graminées adventices, orge sauvage (Hordeum glaucum), l'un résistant et l'autre sensible à I'herbicide paraquat ont étéétudiées pour vé rifier sielles avaient les mêemes caractéristiques de dormance. Sans liaison avec les conditions de stockage au champ, H. glaucum, sensibles et resistantes ont germé facilement après une pé riode identique de dormance initiate de court terme (2 mois). Une expé rimentation de plein champ conduite pour déterminer la longévité des graines d'H. glaucum résistantes dans le sol, a montré qu'en l'absence de nouvelle production grainière, les réserves de cette espéce étaient éliminées en 3 ans. Ces essais montrent que les graines du biotype résistant et H. glaucum ont une vie résiduelle courte dans le stock grainier et que par un empêchement complet de la production grainière pendant 3 ans, il est possible de supprimer ce biotype résistant. Beseitigung einer Paraquat-resistenten Population von Hordeum glaucum Steud. durch dreijährige Verhinderung der Samenneubildung Samen eines gegenüber Paraquat resistenten und eines empfindlichen Biotyps von Hordeum glaucum Steud. wurden auf Dormanz hin untersucht:Ohne Einflußder vorausgegangenen Lagerung unter Feldbedingungen keimten beide Biotypen nach einer kurzen primären Dormanz von 2 Monaten gut. In einem Freilandversuch zur Lebensdauer der Samen resistenter Pflanzen im Boden erschöpfte sich der Samenvorrat bei fehlender Ergänzung innerhalb 3 Jahren. Demnach haben resistente Hordeum-glaucum-Pflanzen nur eine kurze Lebensdauer, und resistente Biotypen können durch Unterbindung der Samenproduktion innerhalb 3 Jahren ausgeschaltet werden.     

Biliary excretion of technetium-99m-sestamibi in wild-type dogs and in dogs with intrinsic (ABCB1-1Δ mutation) and extrinsic (ketoconazole treated) P-glycoprotein deficiency

P-glycoprotein (P-gp), the product of ABCB1 gene, is thought to play a role in the biliary excretion of a variety of drugs, but specific studies in dogs have not been performed. Because a number of endogenous (ABCB1 polymorphisms) and exogenous (pharmacological P-gp inhibition) factors can interfere with normal P-gp function, a better understanding of P-gp's role in biliary drug excretion is crucial in preventing adverse drug reactions and drug–drug interactions in dogs. The objectives of this study were to compare biliary excretion of technetium-99m-sestamibi (^99mTc-MIBI), a radio-labelled P-gp substrate, in wild-type dogs (ABCB1 wild/wild), and dogs with intrinsic and extrinsic deficiencies in P-gp function. Dogs with intrinsic P-gp deficiency included ABCB1 mut/mut dogs, and dogs with presumed intermediate P-gp phenotype (ABCB1 mut/wild). Dogs with extrinsic P-gp deficiency were considered to be ABCB1 wild/wild dogs treated with the P-gp inhibitor ketoconazole (5 mg/kg PO q12h × 9 doses). Results from this study indicate that ABCB1 mut/mut dogs have significantly decreased biliary excretion of ^99mTc-MIBI compared with ABCB1 wild/wild dogs. Treatment with ketoconazole significantly decreased biliary excretion of ^99mTc-MIBI in ABCB1 wild/wild dogs. P-gp appears to play an important role in the biliary excretion of ^99mTc-MIBI in dogs. It is likely that concurrent administration of a P-gp inhibitor such as ketoconazole will decrease P-gp-mediated biliary excretion of other substrate drugs as well.     

MAGNETIC RESONANCE IMAGING OF ACQUIRED TRIGEMINAL NERVE DISORDERS IN SIX DOGS

The medical records and magnetic resonance (MR) images of dogs with an acquired trigeminal nerve disorder were reviewed retrospectively. Trigeminal nerve dysfunction was present in six dogs with histologic confirmation of etiology. A histopathologic diagnosis of neuritis (n=2) or nerve sheath tumor (n=4) was made. Dogs with trigeminal neuritis had diffuse enlargement of the nerve without a mass lesion. These nerves were isointense to brain parenchyma on T1-weighted (T1W) precontrast images and proton-density-weighted (PDW) images and either isointense or hyperintense on T2-weighted (T2W) images. Dogs with a nerve sheath tumor had a solitary or lobulated mass with displacement of adjacent neuropil. Nerve sheath tumors were isointense to the brain parenchyma on T1W, T2W, and PDW images. All trigeminal nerve lesions enhanced following contrast medium administration. Atrophy of the temporalis and masseter muscles, with a characteristic increase in signal intensity on T1W images, were present in all dogs.