Dog breed differences in visual communication with humans

Domestic dogs (Canis familiaris) have developed a close relationship with humans through the process of domestication. In human-dog interactions, eye contact is a key element of relationship initiation and maintenance. Previous studies have suggested that canine ability to produce human-directed communicative signals is influenced by domestication history, from wolves to dogs, as well as by recent breed selection for particular working purposes. To test the genetic basis for such abilities in purebred dogs, we examined gazing behavior towards humans using two types of behavioral experiments: the `visual contact task' and the `unsolvable task'. A total of 125 dogs participated in the study. Based on the genetic relatedness among breeds subjects were classified into five breed groups: Ancient, Herding, Hunting, Retriever-Mastiff and Working). We found that it took longer time for Ancient breeds to make an eye-contact with humans, and that they gazed at humans for shorter periods of time than any other breed group in the unsolvable situation. Our findings suggest that spontaneous gaze behavior towards humans is associated with genetic similarity to wolves rather than with recent selective pressure to create particular working breeds

Fibro-Vascular Coupling in the Control of Cochlear Blood Flow

Transduction of sound in the cochlea is metabolically demanding. The lateral wall and hair cells are critically vulnerable to hypoxia, especially at high sound levels, and tight control over cochlear blood flow (CBF) is a physiological necessity. Yet despite the importance of CBF for hearing, consensus on what mechanisms are involved has not been obtained.We report on a local control mechanism for regulating inner ear blood flow involving fibrocyte signaling. Fibrocytes in the super-strial region are spatially distributed near pre-capillaries of the spiral ligament of the albino guinea pig cochlear lateral wall, as demonstrably shown in transmission electron microscope and confocal images. Immunohistochemical techniques reveal the inter-connected fibrocytes to be positive for Na+/K+ ATPase β1 and S100. The connected fibrocytes display more Ca(2+) signaling than other cells in the cochlear lateral wall as indicated by fluorescence of a Ca(2+) sensor, fluo-4. Elevation of Ca(2+) in fibrocytes, induced by photolytic uncaging of the divalent ion chelator o-nitrophenyl EGTA, results in propagation of a Ca(2+) signal to neighboring vascular cells and vasodilation in capillaries. Of more physiological significance, fibrocyte to vascular cell coupled signaling was found to mediate the sound stimulated increase in cochlear blood flow (CBF). Cyclooxygenase-1 (COX-1) was required for capillary dilation.The findings provide the first evidence that signaling between fibrocytes and vascular cells modulates CBF and is a key mechanism for meeting the cellular metabolic demand of increased sound activity

Behavioural responses to unexpected changes in reward quality

Successive negative contrast (SNC) effects are changes in anticipatory or consummatory behaviour when animals unexpectedly receive a lower value reward than they have received previously. SNC effects are often assumed to reflect frustration and appear to be influenced by background affective state. However, alternative explanations of SNC, such as the functional-search hypothesis, do not necessarily imply an aversive affective state. We tested 18 dogs in a SNC paradigm using a patch foraging task. Dogs were tested in two conditions, once with the low value reward in all of five trials (unshifted) and once when reward value was altered between high and low (shifted). Following a reward downshift, subjects showed a SNC effect by switching significantly more often between patches compared to the unshifted condition. However, approach latency, foraging time and quantity consumed did not differ between conditions, suggesting non-affective functional search behaviour rather than frustration. There was no relationship between strength of SNC and anxiety-related behaviours as measured in a novel object test and a personality questionnaire (C-BARQ). However, associations with the C-BARQ scores for Trainability and Stranger directed aggression suggest a possible link with behavioural flexibility and coping style. While reward quality clearly affects incentive motivation, the relationship between SNC, frustration and background affective state requires further exploration

Sudden bilateral hearing loss in gastric cancer as the only symptom of disease

Zoran Rakusic,1 Ana Misir Krpan,1 Darija Stupin Polancec,2 Antonia Jakovcevic,3 Vesna Bisof1 1Department of Oncology, University Hospital Center Zagreb, 2Fidelta Ltd for Research and Development, 3Department of Pathology, University Hospital Center Zagreb, Zagreb, Croatia Abstract: This paper reports a case of sudden bilateral deafness as the first symptom of gastric cancer, an extremely rare and atypical clinical situation. Because common signs of stomach cancer were absent, the patient was first evaluated in the Department of Otolaryngology, University Hospital Center, Zagreb. Only after expanded diagnostic evaluation and rapid progression of the disease in such a case is a malignant tumor suspected. Treatment is mostly ineffective. The unusual presentation of the disease and the rapid course may indicate a hereditary predisposition. Inactivation of tumor suppressor gene DFNA5 was found in 50% of gastric cancers, but of a non-metastasized phenotype. Inactivated DFNA5, otherwise described in hereditary bilateral deafness, perhaps favors the development of deafness in patients with gastric cancer. Our patient had a positive multiple viral antibody titer in serum, inactivated DFNA5 in both gastric cancer tissues and cerebellar metastases, and a metastatic form of the disease. If sudden deafness occurs in elderly patients, the possibility of malignant tumor should be taken into consideration. The link between gastric cancer and the DFNA5 gene is unclear and requires further research. Keywords: deafness, gastric cancer, DFNA5 gene, meningeal carcinomatosi