Effects of treatment with ticlopidine in heartworm-negative, heartworm-infected, and embolized heartworm-infected dogs.

Ticlopidine hydrochloride was evaluated for its effectiveness in inhibiting platelet aggregation and serotonin release in 5 laboratory Beagles before and after heartworm implantation with 7 adult Dirofilaria immitis, and after embolization with 7 dead heartworms to mimic what happens after heartworm adulticide treatment. Five other laboratory Beagles, similarly implanted and embolized with heartworms, were used as nonmedicated controls. During the heartworm-negative stage, the dosage of ticlopidine that inhibited adenosine diphosphate (ADP)-induced platelet aggregation in 5 dogs by at least 50% after 5 days of treatment was 62 mg/kg of body weight once a day. In the same dogs implanted with 7 adult heartworms 21 days previously, mean (+/- SD) ticlopidine dosage required to obtain similar results was 71 (+/- 13) mg/kg given once daily. During the 21 days after dead heartworms were implanted in heartworm-infected dogs, mean ticlopidine dosage was 108 (+/- 35) mg/kg (range, 62 to 150 mg/kg). Ticlopidine treatment was associated with increased platelet numbers in all 5 dogs during the heartworm-negative stage and in 4 of 5 dogs during the heartworm implantation and heartworm embolization stages. Mean platelet volume tended to decrease as platelet numbers increased. At necropsy, gross and histologic pulmonary lesions were less severe in ticlopidine-treated dogs than in nonmedicated control dogs.     

Treatment of dogs infected with Hepatozoon americanum: 53 cases (1989-1998)

OBJECTIVE: To determine clinical and pathologic findings before and after short-term (group 1) and long-term (group 2) treatment in dogs with Hepatozoon americanum infection. DESIGN: Retrospective study. ANIMALS: 53 dogs with H. americanum infection. PROCEDURE: Medical records of dogs that were treated for hepatozoonosis diagnosed on the basis of meront or merozoite stages in skeletal muscle were reviewed. RESULTS: Circulating gametocytes of H. americanum were identified in 12 of 53 dogs. Dogs were treated with various drugs, including toltrazuril, trimethoprim-sulfadiazine, clindamycin, pyrimethamine, and decoquinate. Mean WBC counts prior to treatment were 85,700 and 75,200 cells/microl in groups 1 and 2, respectively, and 1 month after initiation of treatment were 12,600 and 14,600 cells/microl, respectively. Initial response to treatment was excellent in all dogs. Twenty-three of 26 dogs in group 1 relapsed at least once and died within 2 years; mean (+/- SD) survival time was 12.6+/-2.2 months. Twenty-two of 27 group-2 dogs survived; 11 dogs had no clinical signs and were still receiving decoquinate (mean duration of treatment, 21 months), 11 dogs had no clinical signs after treatment for 14 months (range, 3 to 33 months; mean survival time, 39 months [range, 26 to 53 months]), 2 dogs were lost to follow-up, and 3 dogs were euthanatized because of severe disease. CONCLUSIONS AND CLINICAL RELEVANCE: Although no treatment effectively eliminated the tissue stages of H. americanum, treatment with trimethoprim-sulfadiazine, clindamycin, and pyrimethamine followed by long-term administration of decoquinate resulted in extended survival times and excellent quality of life.     

Metal Pools, Fluxes, and Budgets in an Acidified Forested Catchment on the Precambrian Shield, Central Ontario, Canada

Atmospheric emissions of metals have decreased in North America; yet, metals remain an environmental concern due to their environmental persistence and toxicity to biota. In this study, pools and mass budgets were calculated for 15 metals in an acidified forested catchment in Central Ontario. Metals that were enriched in bulk deposition over background average values (As, Cd, Pb, Zn) were generally enriched in the forest floor and upper lake sediment. While the metal pool in vegetation is small compared with the soil pool, internal cycling of metals via litterfall is comparable to atmospheric deposition, soil water, and stream fluxes. Partitioning coefficients calculated from metal concentrations in soil water and bulk soil suggest that Cd, Mn, Ni, and Zn are the most mobile. The mineral soil and lake sediments were sinks for most metals, while the wetland was a source of metals during the study year, which was a drought year. Overall, lithogenic metals (Al, Ba, Co, Fe, Mn, Rb, Sr, Zn) primarily from a weathering source generally exhibited net export from the catchment, while metals contained in atmospheric pollution (As, Cd, Cr, Cu, Ni, Pb, V) exhibited net retention. Despite the acidified nature of the catchment, it functions to retain many pollutant metals.     

Effects of potato–grain rotations on soil erosion, carbon dynamics and properties of rangeland sandy soils

The potential for wind erosion in South Central Colorado is greatest in the spring, especially after harvesting of crops such as potato (Solanum tuberosum L.) that leave small amounts of crop residue in the surface after harvest. Therefore it is important to implement best management practices that reduce potential wind erosion and that we understand how cropping systems are impacting soil erosion, carbon dynamics, and properties of rangeland sandy soils. We evaluate the effects of cropping systems on soil physical and chemical properties of rangeland sandy soils. The cropping system included a small grain–potato rotation. An uncultivated rangeland site and three fields that two decades ago were converted from rangeland into cultivated center-pivot-irrigation-sprinkler fields were also sampled. Plant and soil samples were collected in the rangeland area and the three adjacent cultivated sites. The soils at these sites were classified as a Gunbarrel loamy sand (Mixed, frigid Typic Psammaquent). We found that for the rangeland site, soil where brush species were growing exhibited C sequestration and increases in soil organic matter (SOM) while the bare soil areas of the rangeland are losing significant amounts of fine particles, nutrients and soil organic carbon (SOM-C) mainly due to wind erosion. When we compared the cultivated sites to the uncultivated rangeland, we found that the SOM-C and soil organic matter nitrogen (SOM-N) increased with increases in crop residue returned into the soils. Our results showed that even with potato crops, which are high intensity cultivated cropping systems, we can maintain the SOM-C with a rotation of two small grain crops (all residue incorporated) and one potato crop, or potentially increase the average SOM-C with a rotation of four small grain crops (all residue incorporated) and one potato crop. Erosion losses of fine silt and clay particles were reduced with the inclusion of small grains. Small grains have the potential to contribute to the conservation of SOM and/or sequester SOM-C and SOM-N for these rangeland systems that have very low C content and that are also losing C from their bare soils areas (40%). Cultivation of these rangelands using rotations with at least two small grain crops can reduce erosion and maintain SOM-C and increasing the number of small grain crops grown successfully in rotation above two will potentially contribute to C and N sequestration as SOM and to the sequestration of macro- and micro-nutrients.     

Local population structure of a naturally occurring metapopulation of the quokka (Setonix brachyurus Macropodidae: Marsupialia)

We investigated the population structure of the quokka (Setonix brachyurus) on the mainland of Western Australia using mark–recapture techniques. Seven previously known local populations and one unconfirmed site supporting the preferred, patchy and discrete, swampy habitat of the quokka were trapped. The quokka is now considered as locally extinct at three sites. The five remaining sites had extremely low numbers, ranging from 1 to 36 individuals. Population density at these sites ranged from 0.07 to 4.3 individuals per hectare. There has been no response to the on-going, 6 year fox control programme occurring in the region despite the quokkas’ high fecundity and this is due to low recruitment levels. The remaining quokka populations in the northern jarrah forest appear to be the terminal remnants of a collapsing metapopulation.     

Detection of bityrosine in cataractous human lens protein

Bityrosine was isolated from the insoluble protein of human cataractous lenses. Identification was based on correspondence with synthetic bityrosine with respect to chromatography, fluorescence, and ultraviolet and mass spectra. It is suggested that the compound may form cross-links with polypeptide chains in old and cataractous lenses, causing significant alteration in native protein structure.