Partitioning the multi-scale effects of human activity on the occurrence of riparian forest birds

Conservationists, managers, and land planners are faced with the difficult task of balancing many issues regarding humans impacts on natural systems. Many of these potential impacts arise from local-scale and landscape-scale changes, but such changes often covary, which makes it difficult to isolate and compare independent effects arising from humans. We partition multi-scale impacts on riparian forest bird distribution in 105 patches along approximately 500 km of the Madison and Missouri Rivers, Montana, USA. To do so, we coupled environmental information from local (within-patch), patch, and landscape scales reflecting potential human impacts from grazing, invasive plant species, habitat loss and fragmentation, and human development with the distribution of 28 terrestrial breeding bird species in 2004 and 2005. Variation partitioning of the influence of different spatial scales suggested that local-scale vegetation gradients explained more unique variation in bird distribution than did information from patch and landscape scales. Partitioning potential human impacts revealed, however, that riparian habitat loss and fragmentation at the patch and landscape scales explained more unique variation than did local disturbances or landscape-scale development (i.e., building density in the surrounding landscape). When distribution was correlated with human disturbance, local-scale disturbance had more consistent impacts than other scales, with species showing consistent negative correlations with grazing but positive correlations with invasives. We conclude that while local vegetation structure best explains bird distribution, managers concerned with ongoing human influences in this system need to focus more on mitigating the effects of large-scale disturbances than on more local land use issues. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Liberalization of Peru's formal seed sector

During the 1990s, the Government of Peru began to aggressivelyprivatize agriculture. The government stopped loaning money to farmers' cooperatives and closed the government rice-buying company. The government even rented out most of its researchstations and many senior scientists lost their jobs. As part of this trend, the government eliminated its seed certification agency. Instead, private seed certification committees were set up with USAID funding and technical advise from a US university. The committees were supposed to become self-financing (bycertifying seed grown by small seed producers) and each committee was supposed to encourage the development of a group of small seed-producing firms, clustered around the seedcertification agency. The amazing thing is that many of the seed committees actually accomplished these goals. The agronomists who staffed the committees stood by their jobs,even after US funding ended, even though the committees' income was (at best) modest, and occasionally under the threat of violence from the extreme left. Some seed certificationcommittees failed and others did not. Some of the problems with Peruvian agricultural liberalization can be seen in regard to the seed programs of maize, rice, potatoes, and beans. For example, the government abandoned most research, yet could not resist creating certain distortions in the seed market (e.g.,buying large amounts of seed and distributing them for political ends).     

Comparison of two radiographic techniques for evaluation of hip joint laxity in 10 breeds of dogs

OBJECTIVE: To evaluate hip joint laxity in 10 breeds of dogs via 2 radiographic techniques. ANIMALS: 500 clinically normal dogs. DESIGN: Prospective study. PROCEDURE: Radiographs obtained via routine hip joint evaluations performed in sedated dogs of 10 popular breeds were randomly selected from a database. Measurements of distraction index (DI) and hip-extended index (HEI) on 1 hip joint radiograph randomly chosen from each dog were made. RESULTS: Mean age of dogs was 20.7 months. Mean HEI was 0.17 (range, 0.0 to 0.72) and mean DI was 0.44 (range, 0.07 to 0.96). Borzois had uniformly tight hip joints as judged by use of both methods and were considered the gold standard by which hip joint laxity was judged (all Borzois had DI < or = 0.32). Overall, DI was significantly greater than HEI. Within each breed, mean DI was always greater than mean HEI. Significant differences were detected among breeds for HEI; however, compared with DI, the magnitude of differences among breeds was less. CONCLUSIONS AND CLINICAL RELEVANCE: Distraction radiography detected the greatest range and magnitude of passive hip laxity in the 10 breeds of dogs. The difference in values between breeds known to have high prevalence of canine hip dysplasia and those in Borzois was greater for DI than for HEI. Breeds must be evaluated individually because of inherent differences in hip joint laxity.     

Immune responses to commercial equine vaccines against equine herpesvirus-1, equine influenza virus, eastern equine encephalomyelitis, and tetanus

Horses are commonly vaccinated to protect against pathogens which are responsible for diseases which are endemic within the general horse population, such as equine influenza virus (EIV) and equine herpesvirus-1 (EHV-1), and against a variety of diseases which are less common but which lead to greater morbidity and mortality, such as eastern equine encephalomyelitis virus (EEE) and tetanus. This study consisted of two trials which investigated the antigenicity of commercially available vaccines licensed in the USA to protect against EIV, EHV-1 respiratory disease, EHV-1 abortion, EEE and tetanus in horses. Trial I was conducted to compare serological responses to vaccines produced by three manufacturers against EIV, EHV-1 (respiratory disease), EEE, and tetanus given as multivalent preparations or as multiple vaccine courses. Trial II compared vaccines from two manufacturers licensed to protect against EHV-1 abortion, and measured EHV-1-specific interferon-gamma (IFN-gamma) mRNA production in addition to serological evidence of antigenicity. In Trial I significant differences were found between the antigenicity of different commercial vaccines that should be considered in product selection. It was difficult to identify vaccines that generate significant immune responses to respiratory viruses. The most dramatic differences in vaccine performance occurred in the case of the tetanus antigen. In Trial II both vaccines generated significant antibody responses and showed evidence of EHV-1-specific IFN-gamma mRNA responses. Overall there were wide variations in vaccine response, and the vaccines with the best responses were not produced by a single manufacturer. Differences in vaccine performance may have resulted from differences in antigen load and adjuvant formulation.     

Endotoxin-neutralizing activity of polymyxin B in blood after IV administration in horses

OBJECTIVES: To measure serum polymyxin B concentration after single and repeated IV infusions in horses. ANIMALS: 5 healthy horses. PROCEDURES: In study 1, 1 mg (6,000 U) of polymyxin B/kg was given IV and blood samples were collected for 24 hours. In study 2, 1 mg of polymyxin B/kg was given IV every 8 hours for 5 treatments and blood samples were collected until 24 hours after the last dose. Polymyxin B concentration was measured as the ability to suppress nitrite production by murine macrophages stimulated with lipopolysaccharide and interferon-alpha. Urine was collected prior to the first drug infusion and 24 hours after the fifth drug infusion for determination of urinary gamma-glutamyl transferase (GGT)-to-creatinine ratios. RESULTS: In study 1, mean +/- SEM maximal serum polymyxin B concentration was 2.93 +/- 0.38 microg/mL. Polymyxin B was undetectable 18 hours after infusion. In study 2, maximal polymyxin B concentrations after the first and fifth doses were 2.98 +/- 0.81 microg/mL and 1.91 +/- 0.50 microg/mL, respectively. Mean trough concentration for all doses was 0.22 +/- 0.01 microg/mL. A significant effect of repeated administration on peak and trough serum concentration was not detected. Urine GGT-to-creatinine ratios were not affected by polymyxin B administration. CONCLUSIONS AND CLINICAL RELEVANCE: Polymyxin B given as multiple infusions to healthy horses by use of this protocol did not accumulate in the vascular compartment and appeared safe. Results support repeated IV use of 1 mg of polymyxin B/kg at 8-hour intervals as treatment for endotoxemia.     

The horizontal barrier effect of stems on the foraging behaviour of cattle grazing five tropical grasses

The rate of nutrient intake (RNI) is a primary determinant of animal performance in grazing cattle and depends on both diet quality and instantaneous intake rate (IIR). In turn, diet quality and IIR are a function of the foraging behaviour of the animal (selectivity, bite mass and bite rate) and the characteristics of the sward. In this study we evaluated the effect of the stem density and the tensile resistance of stems on the foraging behaviour of cattle grazing tropical pasture species. The methodology involved the use of small sown microswards offered to tethered cattle. The experiment consisted of a factorial combination of five tropical grasses [Bothriochloa pertusa (Bp), Chloris barbata (Cb), Chloris gayana (Cg), Cynodon dactylon (Cd) and Heteropogon contortus (Hc)] and three stem densities (0, 400 and 800 stems m^− 2). Bp and Cd had stems of significantly lower tensile resistance (19 and 15 N respectively) (Group 1) than those of Cb, Cg and Hc (110, 211 and 167 N respectively) (Group 2). The steers avoided stems of Group 2 and thus, reduced bite area, bite mass, IIR and RNI as stem density increased. However, the animals did not avoid stems of Group 1 and there was no effect of stem density on any of the foraging behaviour variables when cattle grazed species in Group 1. These results confirm that RNI and plant part selection is closely associated with the tensile resistance of the stem.     

Evaluation of laparoscopic-assisted placement of jejunostomy feeding tubes in dogs

OBJECTIVE: To evaluate feasibility of performing laparoscopic-assisted placement of a jejunostomy feeding tube (J-tube) and compare complications associated with placement, short-term feedings, and medium-term healing with surgically placed tubes in dogs. DESIGN: Prospective study. ANIMALS: 15 healthy mixed-breed dogs. PROCEDURES: Dogs were randomly allocated to undergo open surgical or laparoscopic-assisted J-tube placement. Required nutrients were administered by a combination of enteric and oral feeding while monitoring for complications. Radiographic contrast studies documented tube direction and location, altered motility, or evidence of stricture. RESULTS: Jejunostomy tubes were successfully placed in the correct location and direction in all dogs. In the laparoscopic group, the ileum was initially selected in 2 dogs, 2 dogs developed moderate hemorrhage at a portal site, and 2 J-tubes kinked during placement but were successfully readjusted postoperatively. All dogs tolerated postoperative feedings. All dogs developed minor ostomy site inflammation, and 1 dog developed bile-induced dermatitis at the ostomy site. Despite mild, transient neutrophilia, no significant difference was noted in WBC counts between groups. No dog had altered gastric motility or evidence of stricture, although the jejunopexy site remained identifiable in several dogs at 30 days. CONCLUSIONS AND CLINICAL RELEVANCE: Requirements for successful J-tube placement were met by use of a laparoscopic-assisted technique, and postoperative complications were mild and comparable to those seen with surgical placement. Laparoscopic-assisted J-tube placement compares favorably to surgical placement in healthy dogs and should be considered as an option for dogs requiring enterostomy feeding but not requiring a celiotomy for other reasons.     

In vitro fermentation of alternansucrase raffinose-derived oligosaccharides by human gut bacteria

In this work, in vitro fermentation of alternansucrase raffinose-derived oligosaccharides, previously fractionated according to their degree of polymerization (DP; from DP4 to DP10), was carried out using small-scale pH-controlled batch cultures at 37 °C under anaerobic conditions with human feces. Bifidogenic activity of oligosaccharides with DP4-6 similar to that of lactulose was observed; however, in general, a significant growth of lactic acid bacteria Bacteroides , Atopobium cluster, and Clostridium histolyticum group was not shown during incubation. Acetic acid was the main short chain fatty acid (SCFA) produced during the fermentation process; the highest levels of this acid were shown by alternansucrase raffinose acceptor pentasaccharides at 10 h (63.11 mM) and heptasaccharides at 24 h (54.71 mM). No significant differences between the gas volume produced by the mixture of raffinose-based oligosaccharides (DP5-DP10) and inulin after 24 h of incubation were detected, whereas lower gas volume was generated by DP4 oligosaccharides. These findings indicate that novel raffinose-derived oligosaccharides (DP4-DP10) could be a new source of prebiotic carbohydrates.     

Dialkylphosphates (DAPs) in fruits and vegetables may confound biomonitoring in organophosphorus insecticide exposure and risk assessment

Trace residues of organophosphorus (OP) pesticides are associated with fruits and vegetables that have been sprayed with those OP pesticides to guard against insect pests. Human dietary exposure to these OP pesticides is commonly estimated by measuring the amount of OP metabolites in urine, assuming a stoichiometric relationship between a metabolite and its parent insecticide. Dialkylphosphates (DAPs) are the OP metabolites that are most often used as markers in such biomonitoring studies. However, abiotic hydrolysis, photolysis, and plant metabolism can convert OP chemicals (OP residues) to DAP residues on or in the fruits and vegetables. To evaluate the extent of these conversions, OPs and DAPs were measured in 153 produce samples. These samples from 2 lots were known to contain OP insecticide residues based on routine monitoring by California producers and shippers. A total of 12 OPs were quantified, including mevinphos, naled, acephate, methamidophos, oxidemeton-methyl, azinphos-methyl, dimethoate, malathion, methidathion, phosmet, chlorpyrifos, and diazinon. All OP insecticide residues were below their respective residue tolerances in 2002-2004. A total of 91 of 153 samples (60%) contained more DAP residues than parent OPs. The mean mole fractions [DAPs/(DAPs + OPs)] for the first and second lots of produce were 0.62 and 0.50, respectively, and the corresponding geometric means were 0.55 and 0.34. The corresponding mean mole ratios (DAPs/OP) were 7.1 and 3.4, with geometric means of 2.1 and 0.9. Any preformed DAPs ingested in the diet that are excreted in urine may inflate the estimated absorbed OP insecticide doses in occupational and environmental studies. In subsequent prospective studies, time-dependent production of dimethylphosphate (DMP) and dimethylthiophosphate (DMTP) in strawberries and leaves following malathion sprays occurred concomitant with the disappearance of the parent insecticide and its oxon. DAPs are more persistent in plants and produce at routinely measured levels than their parent OP insecticides.