Hemodynamic effects of acute pneumonia experimentally induced in newborn calves inoculated with Pasteurella haemolytica

Hemodynamic responses to acute pneumonia and to hypoxia were investigated in 10 newborn calves. Experiments were performed on heparinized, anesthesized and ventilated calves. Control calves were inoculated intratracheally with bovine fetal serum. Pneumonia was induced in treated calves by intratracheal inoculation with P haemolytica suspended in bovine fetal serum. Before inoculation (base line), at the time of inoculation (T = 0), and at 30-minute intervals for 3 hours, pulmonary arterial pressure (Ppa), systemic arterial pressure, cardiac output (CO), arterial blood gases, pulmonary vascular resistance (PVR), and systemic vascular resistance were determined. At T = 0, calves in both groups became hypoxemic, alveolar-arterial O2 difference, PVR, and Ppa increased, and CO and systemic vascular resistance remained unchanged. At subsequent measurement intervals, all values returned to base-line in control calves, whereas treated calves had progressive hypoxemia associated with a decrease in Ppa and PVR, with no change in CO. Three hours after inoculation and after inhalation of 10% O2 in N2, PVR increased significantly in the control calves. In the treated group, hypoxia did not increase the resistance, compared with base-line and 3-hour values. The data indicate decreased Ppa during pneumonic pasteurellosis is because of a decrease in PVR and that pneumonia may attenuate the normal pulmonary hypoxic vasoconstrictor response.     

Responses of farmers to introduction in England and Wales of pre-movement testing for bovine tuberculosis

Pre-movement testing (PrMT) for bovine tuberculosis (bTB) was introduced in England and Wales in 2 phases starting in 2006. This study used questionnaires (n=800, response rate=31%) and analysis of national cattle movement records between January 2003 and February 2007 to investigate the impact of PrMT on specific farm management behaviours. A majority of farmers (65%) believed they had not changed their behaviour in response to PrMT; the main reported changes related to decisions regarding selling of cattle. There was evidence in the cattle movement data that introduction of PrMT resulted in reduction of movements of cattle between farms in those areas which must undertake PrMT. The buying behaviour reported by farmers reflected the tendency to buy locally but some farmers reported that others might be more willing to purchase animals from high-risk areas as a result of increased confidence due to PrMT. However, there was little evidence in the movement data of increased movements from high- to low-risk bTB areas following introduction of PrMT. Analysis of the cattle movement data found increased movement of single animals and decreased movement of large batches (>10) of animals (directly) between farms since the introduction of PrMT.     

Particle mapping in stables at an American Thoroughbred racetrack

Reasons for performing study: Airway inflammation and mucus in the trachea are common in racehorses. Fine airborne particles can initiate and coarse particles can worsen airway inflammation in man and in animal models of airway disease. The regional and seasonal distribution of particles of different sizes has never been investigated in American racing stables. Objectives: To determine the regional and seasonal concentration and number of airborne particles of different sizes in racing stables. Methods: Direct reading instruments were used to determine the mass concentration and numbers of particles 3 times daily (early morning, midday and late afternoon) in July, September and November, in 3 different racing stables. Results: Average particle concentrations were lowest in July and highest in September and November. Early morning concentrations were significantly higher than those measured throughout the rest of the day. The completely enclosed stable with little natural ventilation, had significantly higher particulate concentrations than the open‐sided stable. With regard to numbers of particles, those 2–5 µm were greatest in July and least in November; those 0.5–1.0 µm were greatest in September and least in November. Location of stall within stable also affected concentrations and numbers. Conclusions: The concentration and number of particles in sizes known to reach the lower airways varies with stable design/management, time of day, season of year and location of the stall within the stable. Potential relevance: Particle mapping is a useful tool in the identification of stables, season, and location of stalls within stables where horses may be at greater risk of exposure to offending particulates.     

Predictions of biodiversity response to genetically modified herbicide-tolerant crops

We simulated the effects of the introduction of genetically modified herbicide-tolerant (GMHT) crops on weed populations and the consequences for seed-eating birds. We predict that weed populations might be reduced to low levels or practically eradicated, depending on the exact form of management. Consequent effects on the local use of fields by birds might be severe, because such reductions represent a major loss of food resources. The regional impacts of GMHT crops are shown to depend on whether the adoption of GMHT crops by farmers covaries with current weed levels.     

Vasopressin mRNA in the suprachiasmatic nuclei: daily regulation of polyadenylate tail length

Daily variation has been found in the length of the polyadenylate tail attached to vasopressin messenger RNA in the suprachiasmatic nuclei, which is the location of an endogenous circadian pacemaker in mammals. No such variation was found in the supraoptic or paraventricular nuclei. This variation in the length of the polyadenylate tail may underlie the circadian rhythm of vasopressin peptide levels in cerebrospinal fluid and is a unique example of a daily rhythm in messenger RNA structure.     

Volcanism on Mercury: evidence from the first MESSENGER flyby

The origin of plains on Mercury, whether by volcanic flooding or impact ejecta ponding, has been controversial since the Mariner 10 flybys (1974-75). High-resolution images (down to 150 meters per pixel) obtained during the first MESSENGER flyby show evidence for volcanic vents around the Caloris basin inner margin and demonstrate that plains were emplaced sequentially inside and adjacent to numerous large impact craters, to thicknesses in excess of several kilometers. Radial graben and a floor-fractured crater may indicate intrusive activity. These observations, coupled with additional evidence from color images and impact crater size-frequency distributions, support a volcanic origin for several regions of plains and substantiate the important role of volcanism in the geological history of Mercury.     

Atmospheric Effects of Pollutan: Pollutants which affect clouds are most likely to produce modifications in weather and climate

We have argued that aerosols are probably the principal agents by which pollutants may affect weather and climate. They are most likely to act by influencing the structure and distribution of clouds. On the local scale, the effects of pollutants on some aspects of weather are unmistakable. The effects of man-made pollutants on global climate are a matter of debate, but they may already be significant.