Dihydrooxadiazines: Octopaminergic system as a potential site of insecticidal action

Dihydrooxadiazines are structural analogs of octopamine and were compared with octopamine for their ability to compete with [³H]dihydroergocryptine ([³H]DHE) for binding sites on DHE-sensitive receptors, to stimulate adenylate cyclase activity in nervous system homogenates of Periplaneta americana L., and to modulate the action of the peptide proctolin on the oviducal muscles of Locusta migratoria L. [³H]DHE binding was inhibited by low concentrations (μM range) of octopamine, phentolamine, N-demethylchlordimeform (DCDM) and several dihydrooxadiazines. The tested dihydrooxadiazines acted as aminergic agonists in stimulating cyclic AMP production in cockroach nervous system homogenates and did not show additive effects with octopamine, whereas additivity was observed with 5-hydroxytryptamine. The relative potency of octopaminergic antagonists, including mianserin, cyproheptadine, phentolamine, and gramine, to block octopamine-mediated elevation of cyclic AMP production was similar to the rank-order potency of the same antagonists to inhibit dihydrooxadiazine-mediated elevation of cyclic AMP production. Octopamine, 2-(4-bromophenyl)-5,6-dihydro-4H-1,3,4-oxadiazine (4-Br-PDHO), and 8-Br-cyclic AMP caused increased phosphorylation of proteins that are phosphorylated by exogenously added cyclic AMP-dependent protein kinase. These results indicate that the dihydrooxadiazine-induced rise in cyclic AMP levels in homogenates of the cockroach nervous system results directly in activation of an endogenous cyclic AMP-dependent protein kinase. 4-Br-PDHO behaved similarly to octopamine in modulating the action of proctolin-induced contractions in locust oviducal muscles. These observations suggest that dihydrooxadiazines act as octopamine agonists and have an octopaminergic action in modulating the action of proctolin. Thus, it is proposed that dihydrooxadiazines exert at least part of their insecticidal and miticidal actions through interaction with the octopaminergic system.     

Use of endogenous ACTH concentration and adrenal ultrasonography to distinguish the cause of canine hyperadrenocorticism

Twenty-nine dogs were diagnosed with hyperadrenocorticism (HAC). A single determination of endogenous plasma adrenocorticotropic hormone (ACTH) and adrenal ultrasonography were used in a prospective study to differentiate between pituitary-dependent HAC (PDH) and adrenal-dependent HAC (ADH). In 27 out of the 29 dogs (93 per cent), both endogenous plasma ACTH concentrations and adrenal ultrasonography indicated the same cause of HAC. Twenty-one of the 29 cases (72 per cent) were shown to be pituitary-dependent; all had plasma ACTH concentrations of greater than 28 pg/ml (reference range 13 to 46 pg/ml) and both adrenal glands were ultrasonographically of similar size and of normal shape. All 21 cases responded well to mitotane therapy. Six cases (21 per cent) were shown to be adrenal-dependent; all had plasma ACTH concentrations below the limit of the assay (<5 pg/ml) and the presence of an adrenal mass on ultrasonography. The sensitivity and specificity of adrenal ultrasonography and endogenous ACTH determinations to identify the cause of HAC were demonstrated to be 100 per cent and 95 per cent, respectively, for ADH. These discriminatory tests are more accurate than published figures for dexamethasone suppression testing.     

Spontaneous pneumoperitoneum in two cats

Spontaneous pneumoperitoneum is an infrequently observed presentation in cats. This report details two cases of pneumoperitoneum in the cat. The first case was suspected to have been caused by a gastric perforation secondary to gastric lymphoma. The second case was caused by a perforated gastric ulcer in a cat that had been recently treated with corticosteroids and a non-steroidal anti-inflammatory drug.     

Horner's syndrome associated with a mandibular symphyseal fracture and bilateral temporomandibular luxation.

Interruption of the postganglionic neuron in the sympathetic pathway to the eye is reported to be a common cause of Horner's syndrome in the cat, although there are few clinical reports identifying the site and nature of the lesion responsible. A case of Horner's syndrome resulting from trauma to the periorbital structures following reduction of temporomandibular joint luxation is presented. In this case, the ophthalmic abnormalities resolved spontaneously over eight days.     

Increase in activity during calorie restriction requires Sirt1

Sir2 (silent information regulator 2) is a nicotinamide adenine dinucleotide-dependent deacetylase required for longevity due to calorie restriction in yeast and Drosophila. In mammals, calorie restriction induces a complex pattern of physiological and behavioral changes. Here we report that the mammalian Sir2 ortholog, Sirt1, is required for the induction of a phenotype by calorie restriction in mice.     

Polar lightning and decadal-scale cloud variability on Jupiter

Although lightning has been seen on other planets, including Jupiter, polar lightning has been known only on Earth. Optical observations from the New Horizons spacecraft have identified lightning at high latitudes above Jupiter up to 80 degrees N and 74 degrees S. Lightning rates and optical powers were similar at each pole, and the mean optical flux is comparable to that at nonpolar latitudes, which is consistent with the notion that internal heat is the main driver of convection. Both near-infrared and ground-based 5-micrometer thermal imagery reveal that cloud cover has thinned substantially since the 2000 Cassini flyby, particularly in the turbulent wake of the Great Red Spot and in the southern half of the equatorial region, demonstrating that vertical dynamical processes are time-varying on seasonal scales at mid- and low latitudes on Jupiter.     

Marking of deer fences to reduce frequency of collisions by woodland grouse

Recent studies of the effects of deer fences on tetraonids have concluded that fences are an important cause of mortality in woodland grouse. This 2-year study involving 16 sections of fences in the Scottish Highlands evaluates the effectiveness of making fences highly visible by using orange netting to reduce bird collisions with fences. A total of 437 collisions involving 13 bird species were recorded. Red grouse (Lagopus lagopus scoticus) formed 42% of all collisions, with black grouse (Tetrao tetrix) 29% and capercaillie (T. urogallus) 20%. Allowing for corpse removal by scavengers, an estimated 70% of red grouse and 29% of black grouse collisions were fatal. Black grouse and capercaillie both collided with 11 of the 16 fences at mean rates of 1.3 and 0.9 collisions km⁻¹ year⁻¹, red grouse collisions occurred at 13 fences, with a mean rate of 1.6 collisions km⁻¹ year⁻¹. Fewer grouse collisions occurred in the summer. Three quarters of black grouse collisions were by males. Collision rates were positively correlated with indices of black grouse and capercaillie abundance. Fence marking reduced capercaillie collisions by 64%, black grouse by 91% and red grouse by 49%. Although marked fences reduced capercaillie collision rates, they still remained an important cause of mortality. To conserve capercaillie, fences need to be removed altogether pending increased deer culls that would allow woodland regeneration without fences, or “grouse friendly” fences designed.     

Panniculitis associated with pancreatitis in a cocker spaniel

A 13-year-old, male cocker spaniel presented with a history of inappetence, depression and reluctance to stand. The dog had multiple, ulcerated skin lesions which were diagnosed as panniculitis by histopathology. A diagnosis of pancreatitis was made on the basis of markedly elevated serum lipase concentrations, abdominal ultrasonography which showed an abnormal lobulated area of hypoechoic tissue in the body and right lobe of the pancreas, and a fine needle biopsy from this area which revealed large numbers of degenerate neutrophils. After treatment with antibiotics and prednisolone, the dog made a full clinical recovery and was free of clinical signs for four months. The dog was euthanased five months later and postmortem examination revealed chronic, active pancreatitis and a pancreatic adenoma. This is the first report of antemortem diagnosis of pancreatitis and panniculitis in a dog.     

Excision of the distal sesamoid bone for treatment of infection of the digit in a heifer.

An 8-month-old Holstein heifer was evaluated for right hind limb lameness of 3 weeks' duration. Diagnoses were osteomyelitis and fracture of the distal sesamoid bone, septic arthritis of the distal interphalangeal joint, and osteomyelitis of the third phalanx. After excision of a section of tissue from the plantar aspect of the digit and partial section of the deep digital flexor tendon, the distal sesamoid bone was excised. The third phalanx was curetted, and the surgical wound was lavaged. Twenty months after surgery, the heifer was fully weightbearing on the affected digit. Surgical exploration of the digit should be considered an alternative to claw amputation in cattle that have severe digital infections.