An overview of types of aggressive behaviour in dogs and methods of treatment

In 223 cases of dogs presented to a specialist behavioural clinic in Brisbane, Australia, 87 (39%) were for severe aggression. The classes of aggression included dominance (31.6%), territorial (29%), predatory (12.3%), intermale (12.3%), sibling rivalry (7.9%), fear biting (6%) and idiopathic rage (0.9%). The breeds most represented which attacked humans were the Bull Terrier (16%), German Shepherd and crosses (15%), Cattle dog breeds (Blue Heeler and crosses, 9.2%), Terrier breeds (9.2%), Labrador (8%), Poodle and Cocker Spaniel (both 5.7%) and Rottweiler (4.6%). The dangerous dog list put out by the local Brisbane City Council includes the first three breeds mentioned and the Rottweiler as the top four breeds causing aggression problems.

Hospital records in Victoria and Queensland confirm that most damage is caused to humans by Bull Terriers and German Shepherds. Many breeds similar to those in our study are also represented in American data on aggressive breeds.

Treatments included obedience training only, restraint only, obedience and restraint, synthetic progestins and obedience, castration, progestins and obedience, castration and obedience, use of chlorpromazine and as a last resort, euthanasia (12.6%). Entire males formed the largest group (44%), followed by castrated males and females (both 21%) and spayed females (15%).

Several breeds (Boxer, Briand, Samoyed and St. Bernard) only attacked other animals and birds.

This study reinforces evidence that social disruption is caused by aggressive dogs, but it also indicates that many responsible clients seek advice on how to deal with this behavioural problem.     

Billingen (Lower Arenig/Lower Ordovician) acritarchs from the East European Platform and their palaeobiogeographic significance

Billingen (Lower Arenig/Lower Ordovician) sediments of the St. Petersburg region, northwest Russia and the Leba area, northern Poland of the East European Craton yield acritarch assemblages, which are largely homogenous though displaying minor compositional differences that probably reflect a gradient from inner to outer shelf environments. Comparison with coeval acritarch microflora from the Yangtze Platform, South China, shows an overall similarity between Baltoscandian and South Chinese phytoplankton. The widespread uniformity in the fossil microphytoplankton may be related to the extensive global 'evae' sea-level transgression, which characterized the Billingen time. This suggests that during the Tremadoc through early Arenig times, acritarch assemblages displayed essentially an undifferentiated cold-water and oceanic character along the whole margin of Perigondwana in the South, as well as on the South Chinese and Baltic platforms, at middle latitudes (Mediterranean oceanic Realm). Despite this overall similarity, however, some typical taxa of the high-latitude Mediterranean Province (Arbusculidium, Coryphidium and Striatotheca) occur in South China, but are absent in Baltica. This discrepancy is explained as caused by differences in climatic and physiographic conditions that prevailed at the two palaeocontinents at this time. The inferred pattern of oceanic circulation during the Lower Ordovician is consistent with the palynological evidence of a prevailing warmer climate in Baltica than in South China, although the two palaeocontinents occupied the same palaeolatitudinal position.     

Ultrastructural observations on rhabdite formation in the planarian, Artioposthia triangulata

The epidermis of the predatory terrestrial flatworm, Artioposthia triangulata has been examined by transmission electron microscopy for the presence of rhabdiform secretions. Two types of secretion are present: epidermal rhabdoids, produced by a special type of epidermal cell and true adenal rhabdites produced by gland cells beneath the epidermis. The epidermal rhabdoids are formed from Golgi-derived vesicles, which fuse together to form the developing rhabdoid. Within the latter is a filamentous network on which granular material is deposited and coalesces to form a rod-shaped inclusion. The rhabdoids accumulate in the apical region of the cell and release their contents from the apical surface. The adenal rhabdites are formed by Golgi-derived vesicles, which become more elongated and their contents more electron-dense as they mature. The vesicles fuse together to form the primordial rhabdite, which continues to lengthen with the addition of further vesicles. The neck of the rhabdite-forming cell passes between the muscle layers and through the basement membrane to open into the base of the epidermal cell. The rhabdites move from the cell body through the neck into the cytoplasm of the epidermal cell and make their way to the apical surface where they are released to the exterior.     

Collagen biosynthesis in cultured rat testicular Sertoli and peritubular myoid cells.

The incorporation of 3H-proline into protein was regarded as a measure of total protein synthesis and the incorporation into hydroxyproline as indicative of collagen synthesis. Relative collagen synthesis (expressed as percent of total protein synthesized) by Sertoli and peritubular myoid cells cultured from 20-22 day old rat testis was estimated. In both secreted and cellular pools, relative collagen synthesis by Sertoli cells was significantly greater than by peritubular myoid cells. Coculture of Sertoli and myoid cells resulted in a significant increase in relative collagen synthesis when compared to monocultures of each cell type. Addition of serum to peritubular myoid cells resulted in a stronger stimulation of relative collagen production. Sertoli cell extracellular matrix inhibited relative collagen synthesis by peritubular myoid cells in the presence or absence of serum. Radioactivity into hydroxyproline as corrected per cellular DNA also showed similar results. Immunolocalization studies confirmed that both cell types synthesize type I and type IV collagens. These results indicate that stimulation of collagen synthesis observed in Sertoli-myoid cell cocultures is due to humoral interactions, rather than extracellular matrix, and Sertoli cell extracellular matrix regulates serum-induced increase in collagen synthesis by peritubular myoid cells.     

The impairment argument for the immorality of abortion revisited

Eric Vogelstein has defended Don Marquis' ‘future-like-ours' argument for the immorality of abortion against what is known as the Identity Objection, which contends that for a fetus to have a future like ours, it must be numerically identical to an entity like us that possesses valuable experiences some time in the future. On psychological accounts of personal identity, there is no identity relationship between the fetus and the entity with valuable experiences that it will become. Vogelstein maintains that a non-sentient fetus nonetheless has a future like ours because it is numerically identical with a future organism that has a mind that bears valuable experiences. Skott Brill, drawing on Jeff McMahan's embodied mind account, denies that human organisms directly have experiences, claiming that they only have experiences derivatively by virtue of their thinking part, and the loss of a future like ours is not transferred to the organism. I show that on McMahan's account, a strong case can be made for the organism having experiences directly, and the subject having these experiences derivatively. This negates Brill's reasoning, although it does imply that non-sentient fetuses do not have a future like ours in quite the same way as we do. I conclude that this is not problematic for Marquis' argument.     

Heme oxygenase-2 is neuroprotective in cerebral ischemia

Heme oxygenase (HO) is believed to be a potent antioxidant enzyme in the nervous system; it degrades heme from heme-containing proteins, giving rise to carbon monoxide, iron, and biliverdin, which is rapidly reduced to bilirubin. The first identified isoform of the enzyme, HO1, is an inducible heat-shock protein expressed in high levels in peripheral organs and barely detectable under normal conditions in the brain, whereas HO2 is constitutive and most highly concentrated in the brain. Interestingly, although HO2 is constitutively expressed, its activity can be modulated by phosphorylation. We demonstrated that bilirubin, formed from HO2, is neuroprotectant, as neurotoxicity is augmented in neuronal cultures from mice with targeted deletion of HO2 (HO2(-/-)) and reversed by low concentrations of bilirubin. We now show that neural damage following middle cerebral artery occlusion (MCAO) and reperfusion, a model of focal ischemia of vascular stroke, is substantially worsened in HO2(-/-) animals. By contrast, stroke damage is not significantly altered in HO1(-/-) mice, despite their greater debility. Neural damage following intracranial injections of N-methyl-d-aspartate (NMDA) is also accentuated in HO2(-/-) animals. These findings establish HO2 as an endogenous neuroprotective system in the brain whose pharmacologic manipulation may have therapeutic relevance.     

Convergence of mechanosensory inputs onto neuromodulatory serotonergic neurons in the leech

By the frequency-dependent release of serotonin, Retzius neurons in the leech modulate diverse behavioral responses of the animal. However, little is known about how their firing pattern is produced. Here we have analyzed the effects of mechanical stimulation of the skin and intracellular stimulation of mechanosensory neurons on the electrical activity of Retzius neurons. We recorded the electrical activity of neurons in ganglia attached to their corresponding skin segment by segmental nerve roots, or in isolated ganglia. Mechanosensory stimulation of the skin induced excitatory synaptic potentials (EPSPs) and action potentials in both Retzius neurons in a ganglion. The frequency and duration of responses depended on the strength and duration of the skin stimulation. Retzius cells responded after T and P cells, but before N cells, and their sustained responses correlated with the activity of P cells. Trains of five impulses at 10 Hz in every individual T, P, or N cell in isolated ganglia produced EPSPs and action potentials in Retzius neurons. Responses to T cell stimulation appeared after the first impulse. In contrast, the responses to P or N cell stimulation appeared after two or more presynaptic impulses and facilitated afterward. The polysynaptic nature of all the synaptic inputs was shown by blocking them with a high calcium/magnesium external solution. The rise time distribution of EPSPs produced by the different mechanosensory neurons suggested that several interneurons participate in this pathway. Our results suggest that sensory stimulation provides a mechanism for regulating serotonin-mediated modulation in the leech.