Atmospheric and oceanic impacts of Antarctic glaciation across the Eocene-Oligocene transition.

The glaciation of Antarctica at the Eocene-Oligocene transition (approx. 34 million years ago) was a major shift in the Earth's climate system, but the mechanisms that caused the glaciation, and its effects, remain highly debated. A number of recent studies have used coupled atmosphere-ocean climate models to assess the climatic effects of Antarctic glacial inception, with often contrasting results. Here, using the HadCM3L model, we show that the global atmosphere and ocean response to growth of the Antarctic ice sheet is sensitive to subtle variations in palaeogeography, using two reconstructions representing Eocene and Oligocene geological stages. The earlier stage (Eocene; Priabonian), which has a relatively constricted Tasman Seaway, shows a major increase in sea surface temperature over the Pacific sector of the Southern Ocean in response to the ice sheet. This response does not occur for the later stage (Oligocene; Rupelian), which has a more open Tasman Seaway. This difference in temperature response is attributed to reorganization of ocean currents between the stages. Following ice sheet expansion in the earlier stage, the large Ross Sea gyre circulation decreases in size. Stronger zonal flow through the Tasman Seaway allows salinities to increase in the Ross Sea, deep-water formation initiates and multiple feedbacks then occur amplifying the temperature response. This is potentially a model-dependent result, but it highlights the sensitive nature of model simulations to subtle variations in palaeogeography, and highlights the need for coupled ice sheet-climate simulations to properly represent and investigate feedback processes acting on these time scales.

Assessment of 8-OH-DPAT induced spontaneous tailflicks as an in vivo model of 5-HT1A function in young rats.

Spontaneous tailflicks, measured as elevation of the tail above the body axis in restrained animals, have been studied in both adult and young rats. The selective 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), induced dose-related increases in spontaneous tailflicks in adult (> 60 days) male rats. These responses were antagonised by the 5-HT1A antagonists (-)-propranolol and (-)-pindolol. 8-OH-DPAT (1 mg/kg) induced tailflicks could be observed in 30, 25 and 20 day old male rats and were also antagonised by (-)-propranolol and (-)-pindolol although drug-induced rotation of the 20 and 25 day old animals hindered assessment. At 14 and 10 days, 8-OH-DPAT (1 mg/kg) produced Straub tail responses which precluded the observation of tailflicks. Lower doses of 8-OH-DPAT, which did not elicit Straub tail in these younger animals also failed to produce tailflicks. Thus 8-OH-DPAT induced spontaneous tailflicks reflect in vivo activation of 5-HT1A receptors in adult and 30 day old male rats but are inappropriate for the study of 5-HT1A mediated behaviour in younger animals.

Functional dyspepsia: the economic impact to patients.

BACKGROUND: Although highly prevalent, little is known about the economic impact of functional dyspepsia (FD). AIMS: To quantify FD patients' health care utilisation patterns and to estimate direct and indirect costs of FD to patients. METHODS: ICD-9 codes identified adult patients with dyspepsia. A validated questionnaire was mailed to patients who met Rome III criteria for FD. RESULTS: Three hundred and fifty-five patients met all inclusion criteria. The response rate was 63%. The respondents' mean age was 50 (14) years; 75% were women; 52% of respondents rated their FD as moderate. Patients reported 3 visits (mean) to their PCP over 12 months; 75% reported having blood work, 92% an EGD, 59% an ultrasound and 40% a CT scan. The direct cost of testing using Medicare reimbursement rates per patient was $582. To treat FD symptoms, 89% tried dietary changes, 89% over-the-counter medications, 87% prescription medications and 25% alternative therapies. Mean patient expenditure over the last year was $246 for OTC medications (range $0-12,000), $290 for co-payments (range $0-9,000) and $110 for alternative treatments (range $0-3,741). Total mean direct cost yearly to patients was $699. In the 7 days prior to completing the questionnaire, respondents reported a mean of 1.4 h absence from work. Extrapolating the results to the US population, we conservatively calculate the costs of FD were $18.4 billion in 2009. CONCLUSIONS: Functional dyspepsia patients incur significant direct and indirect costs and work productivity is impaired by dyspeptic symptoms.