Milk Thistle and Its Derivative Compounds: A Review of Opportunities for Treatment of Liver Disease

Milk thistle extracts have been used as a “liver tonic” for centuries. In recent years, silibinin, the active ingredient in milk thistle extracts, has been studied both in vitro and in vivo to evaluate the beneficial effects in hepatic disease. Silibinin increases antioxidant concentrations and improves outcomes in hepatic diseases resulting from oxidant injury. Silibinin treatment has been associated with protection against hepatic toxins, and also has resulted in decreased hepatic inflammation and fibrosis. Limited information currently is available regarding silibinin use in veterinary medicine. Future study is justified to evaluate dose, kinetics, and treatment effects in domestic animals.     

Pinyon and Juniper Encroachment into Sagebrush Ecosystems Impacts Distribution and Survival of Greater Sage-Grouse

In sagebrush (Artemisia spp.) ecosystems, encroachment of pinyon (Pinus spp.) and juniper (Juniperus spp.; hereafter, “pinyon-juniper”) trees has increased dramatically since European settlement. Understanding the impacts of this encroachment on behavioral decisions, distributions, and population dynamics of greater sage-grouse (Centrocercus urophasianus) and other sagebrush obligate species could help benefit sagebrush ecosystem management actions. We employed a novel two-stage Bayesian model that linked avoidance across different levels of pinyon-juniper cover to sage-grouse survival. Our analysis relied on extensive telemetry data collected across 6 yr and seven subpopulations within the Bi-State Distinct Population Segment (DPS), on the border of Nevada and California. The first model stage indicated avoidance behavior for all canopy cover classes on average, but individual grouse exhibited a high degree of heterogeneity in avoidance behavior of the lowest cover class (e.g., scattered isolated trees). The second stage modeled survival as a function of estimated avoidance parameters and indicated increased survival rates for individuals that exhibited avoidance of the lowest cover class. A post hoc frailty analysis revealed the greatest increase in hazard (i.e., mortality risk) occurred in areas with scattered isolated trees consisting of relatively high primary plant productivity. Collectively, these results provide clear evidence that local sage-grouse distributions and demographic rates are influenced by pinyon-juniper, especially in habitats with higher primary productivity but relatively low and seemingly benign tree cover. Such areas may function as ecological traps that convey attractive resources but adversely affect population vital rates. To increase sage-grouse survival, our model predictions support reducing actual pinyon-juniper cover as low as 1.5%, which is lower than the published target of 4.0%. These results may represent effects of pinyon-juniper cover in areas with similar ecological conditions to those of the Bi-State DPS, where populations occur at relatively high elevations and pinyon-juniper is abundant and widespread.     

Pharmacokinetics of ceftiofur and metabolites after single intravenous and intramuscular administration and multiple intramuscular administrations of ceftiofur sodium to sheep

Twenty-four sheep (38.0–54.1 kg body wt) were allocated into four treatment groups and dosed with ceftiofur sodium at 1.1 mg ceftiofur free acid equivalents (CFAE)/kg or 2.2 CFAE/kg using a complete two-route (intravenous, i.v.; intramuscular, i.m.), two-period crossover design, with a two-week washout between injections. After another two-week washout period, 12 sheep were selected and dosed with ceftiofur sodium i.m. for five consecutive days at either 1.1 or 2.2 mg CFAE/kg. After all injections, blood samples were obtained serially for determination of serum concentrations of ceftiofur and metabolites. The terminal phase half-lives derived from the last 3–5 concentration-time points were 350 and 292 min (harmonic means) after i.v. doses of 1.1 and 2.2 mg/kg, respectively, and 389 and 459 min after i.m. doses of 1.1 and 2.2 mg/kg, respectively. The i.m. bioavailability of ceftiofur sodium in sheep was 100%, and the area under the curve from time 0 to the limit of quantitation ( AUC _0–LOQ) was dose-proportional from 1.1–2.2 mg CFAE/kg body wt in sheep. After 5 daily i.m. doses of ceftiofur sodium at either 1.1 or 2.2 mg CFAE/kg there was minimal accumulation of drug in serum as assessed by the observed maximum serum concentration ( C _max), and serum concentrations were dose-proportional after the multiple dosing regimen.     

Systemic distribution of blood flow in ponies during 1.45%, 1.96%, and 2.39% end-tidal isoflurane-O2 anesthesia

Effects of 1.1, 1.5, and 1.8 minimal alveolar concentration (MAC) isoflurane-O2 (1.45%, 1.96%, and 2.39% end-tidal isoflurane, respectively) anesthesia on cardiac output, blood pressure, and blood flow to the brain, thyroid glands, adrenal glands, kidneys, and splanchnic organs were examined in 9 healthy isocapnic adult ponies. Tissue blood flows were studied using 15-micron diameter radionuclide-labeled microspheres that were injected into the left ventricle, and comparisons were made with data obtained from ponies in the conscious state. Isoflurane anesthesia caused dose-related reduction in cardiac output and arterial blood pressure, but total peripheral resistance was not significantly altered (P greater than 0.05). In the brain, vasodilation occurred with exposure to isoflurane that peaked at 1.5 MAC. Vasodilation was more pronounced in the cerebellum, pons, and medulla, compared with that in the cerebrum. Perfusion increased in cerebellar gray, as well as white, matter. However, in the cerebrum, blood flow increased in the white matter, whereas it decreased in caudate nuclei and was similar to value in the cortex of awake ponies. In thyroid glands and pancreas, intense vasoconstriction occurred during isoflurane anesthesia which caused precipitous reduction in blood flow in these organs. By contrast, adrenal gland blood flow was not affected during the 3 levels of isoflurane anesthesia because vasodilation occurred. The renal blood flow registered dose-dependent reductions during isoflurane-O2 anesthesia, but renal vasoconstriction occurred only during the deepest level (1.8 MAC) of anesthesia. Although the small intestine and and colon blood flow decreased with each concentration of isoflurane, the splenic blood flow remained unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of forest management alternatives and land type on susceptibility to fire in northern Wisconsin,USA

We used the LANDIS disturbance and succession model to study the effects of six alternative vegetation management scenarios on forest succession and the subsequent risk of canopy fire on a 2791 km² landscape in northern Wisconsin, USA. The study area is a mix of fire-prone and fire-resistant land types. The alternatives vary the spatial distribution of vegetation management activities to meet objectives primarily related to forest composition and recreation. The model simulates the spatial dynamics of differential reproduction, dispersal, and succession patterns using the vital attributes of species as they are influenced by the abiotic environment and disturbance. We simulated 50 replicates of each management alternative and recorded the presence of species age cohorts capable of sustaining canopy fire and the occurrence of fire over 250 years. We combined these maps of fuel and fire to map the probability of canopy fires across replicates for each alternative. Canopy fire probability varied considerably by land type. There was also a subtle, but significant effect of management alternative, and there was a significant interaction between land type and management alternative. The species associated with high-risk fuels (conifers) tend to be favored by management alternatives with more disturbances, whereas low disturbance levels favor low-risk northern hardwood systems dominated by sugar maple. The effect of management alternative on fire risk to individual human communities was not consistent across the landscape. Our results highlight the value of the LANDIS model for identifying specific locations where interacting factors of land type and management strategy increase fire risk.This revised version was published online in May 2005 with corrections to the Cover Date.     

Using expert opinion to identify risk factors important to infectious salmon-anemia (ISA) outbreaks on salmon farms in Maine, USA and New Brunswick, Canada

Thirty industry or regulatory professionals, with extensive experience in the local infectious salmon-anemia (ISA) epidemic, were queried on their opinions regarding the spread and impact of ISA in Maine, USA and New Brunswick, Canada. Subjective probability-estimation techniques were used to elicit likelihood ratios (LR) for risk factors of potential relevance to the epidemic. Experts were asked to answer questions based on their direct and local experience with ISA, rather than through knowledge gained from scientific references or experience in other regions. The results found the strongest independent predictors of ISA infection to include (1) a site's proximity to other farms with clinically infected fish, (2) a previous history of ISA on the site, (3) whether a site fallows for a month or more between year classes and (4) whether the site employs harvest vessels practicing full containment of blood and stun water. The strongest predictors of ISA severity included (1) stocking density, (2) the length of time between infection and removal of infected fish, (3) whether fish are moved between pens (after infection) and (4) a farm's sea-lice (Lepeophtheirus salmonis) status. Experts believed that transmission of ISA virus during the local epidemic was influenced by proximity (spatial and temporal) to activities resulting in large-scale shedding of virus into a shared water column, and that severity of infection corresponded more to infected-fish removal practices and certain husbandry decisions. Personnel and equipment biosecurity measures were not seen as strong predictors of either infection or severity in this analysis, though their perceived level of importance was greater among government than industry experts.     

Tibial plateau leveling osteotomy in a llama with a ruptured cranial cruciate ligament

A 3-year-old 155-kg (342-lb) castrated male llama was examined because of left hind limb lameness of acute onset. A diagnosis of cranial cruciate ligament and medial collateral ligament rupture was made, and tibial plateau leveling osteotomy was recommended. The tibial plateau leveling osteotomy procedure was performed as described for dogs, except that 2 orthopedic plates were used to stabilize the osteotomy because of the size of the llama. The medial collateral ligament was sutured and reinforced with 2 strands of size-2 polypropylene placed in a figure-8 fashion between cancellous bone screws in the femur and tibia. Four days after surgery, failure of the medial collateral ligament repair was evident. Approximately 3.5 years after surgery, the llama was reexamined. The owners reported that the llama had full use of its left hind limb, and only mild lameness (grade 1 of 5) was evident. Results suggest that tibial plateau leveling osteotomy may be applicable in camelids with rupture of the cranial cruciate ligament. However, additional study is needed before tibial plateau leveling osteotomy can be routinely recommended. In particular, additional information is needed on the tibial plateau slope in healthy camelids, the role of the fibula in tibial plateau leveling osteotomy procedures, and the prevalence of cranial cruciate ligament rupture in camelids.