The long-term effects of catchment liming and reduced sulphur deposition on forest soils and runoff chemistry in southwest Sweden

Whole catchment liming or forest liming has been proposed and implemented as a countermeasure to the effects of elevated sulphur deposition. Since the end of the 1980s the Swedish Forest Agency has undertaken experimental forest liming experiments in selected catchments in southern Sweden. These studies were with low doses (3 tonnes ha⁻¹) of lime (CaCO₃) and dolomite (CaMg(CO₃)₂). Data from both soil samples and stream water samples have been collected for the 16 years following treatment. The stream data has been complemented with data from untreated catchments, from the Swedish monitoring stream network. Significant differences due to treatment were seen for Ca, cation exchange capacity (CEC) and base saturation (BS) in the humus layer, none of these variables showed a statistically significant change in the mineral soil due to treatment alone. Soil samples from both the treated and untreated sites showed temporal changes in both the humus layer and the mineral soils with increases in pH, Ca and CEC and decreases in BS and Al which were independent of treatment. A combination of treatment and time, gave significant changes in BS and TA down to 10 cm in the mineral soil. In the stream water samples no statistically significant differences were observed between treated and untreated sites. Regardless of treatment, the streams exhibited a general pattern of declining concentrations of SO₄, Ca, sum of base cations (BC) and increasing acid neutralizing capacity (ANC). In summary, the application of a low dose of lime (3 tonnes ha⁻¹) did not result in significant changes in surface water chemistry in the study catchments and changes in soil chemistry were mainly restricted to the humus layer during the 16 years following treatment. The natural recovery, as a result of reductions in sulphur deposition, dominated the effects and was clearly seen in both the treated and untreated study sites. MAGIC simulations indicate that this recovery will continue in the coming decades.     

Investigations on the efficacy of routinely used phenotypic methods compared to genotypic approaches for the identification of staphylococcal species isolated from companion animals in Irish veterinary hospitals

Background

Identification of Staphylococci to species level in veterinary microbiology is important to inform therapeutic intervention and management. We report on the efficacy of three routinely used commercial phenotypic methods for staphylococcal species identification, namely API Staph 32 (bioMérieux), RapID (Remel) and Staph-Zym (Rosco Diagnostica) compared to genotyping as a reference method to identify 52 staphylococcal clinical isolates (23 coagulase positive; 29 coagulase negative) from companion animals in Irish veterinary hospitals.

Results

Genotyping of a 412 bp fragment of the staphylococcal tuf gene and coagulase testing were carried out on all 52 veterinary samples along with 7 reference strains. In addition, genotyping of the staphylococcal rpoB gene, as well as PCR-RFLP of the pta gene, were performed to definitively identify members of the Staphylococcus intermedius group (SIG). The API Staph 32 correctly identified all S. aureus isolates (11/11), 83% (10/12) of the SIG species, and 66% (19/29) of the coagulase negative species. RapID and Staph-Zym correctly identified 61% (14/23) and 0% (0/23) respectively of the coagulase-positives, and 10% (3/29) and 3% (1/29) respectively of the coagulase-negative species.

Conclusions

Commercially available phenotypic species identification tests are inadequate for the correct identification of both coagulase negative and coagulase positive staphylococcal species from companion animals. Genotyping using the tuf gene sequence is superior to phenotyping for identification of staphylococcal species of animal origin. However, use of PCR-RFLP of pta gene or rpoB sequencing is recommended as a confirmatory method for discriminating between SIG isolates.     

Development of a One-Step Real-Time Polymerase Chain Reaction Assay for Diagnosis of Phytophthora ramorum

ABSTRACT Phytophthora ramorum is a recently described pathogen causing bleeding cankers, dieback, and leaf blight on trees and shrubs in parts of Europe and North America, where the disease is commonly known as sudden oak death. This article describes the development of a single-round real-time polymerase chain reaction (PCR) assay based on TaqMan chemistry, designed within the internal transcribed spacer 1 region of the nuclear ribosomal (nr)RNA gene for detection of P. ramorum in plant material. Unlike previously described methods for the molecular detection of P. ramorum, this assay involves no post amplification steps or multiple rounds of PCR. The assay was found to have a limit of detection of 10 pg of P. ramorum DNA, and could detect P. ramorum in plant material containing 1% infected material by weight within 36 cycles of PCR. The assay also was used to test DNA from 28 other Phytophthora spp. to establish its specificity for P. ramorum. A quick and simple method was used to extract DNA directly from host plant material, and detection of P. ramorum was carried out in multiplex with an assay for a gene from the host plant in order to demonstrate whether amplifiable DNA had been extracted. Amplifiable DNA was extracted from 84.4% of samples, as demonstrated by amplification of host plant DNA. The real-time protocol was used to test 320 plant samples (from 19 different plant species) from which DNA extraction had been successful, and was shown to give results comparable with a traditional isolation technique for diagnosis of P. ramorum in plant material from common U.K. hosts.     

A Biomechanical Comparison of Headless Tapered Variable Pitch and AO Cortical Bone Screws for Fixation of a Simulated Lateral Condylar Fracture in Equine Third Metacarpal Bones

OBJECTIVE: To compare drilling, tapping, and screw-insertion torque, force, and time for the 4.5-mm AO and 6.5-mm Acutrak Plus (AP) bone screws, and to compare the mechanical shear strength and stiffness of a simulated complete lateral condylar fracture of the equine third metacarpal bone (MC3) stabilized with either an AO or AP screw. STUDY DESIGN: In vitro biomechanical assessment of screw-insertion variables, and shear failure tests of a bone-screw-stabilized simulated lateral condylar fracture. SAMPLE POPULATION: Eight pairs of cadaveric equine MC3s METHODS: Metacarpi were placed in a fixture and centered on a biaxial load cell in a materials-testing system to measure torque, compressive force, and time for drilling, tapping, and screw insertion. Standardized simulated lateral condylar fractures were stabilized by either an AO or AP screw and tested in shear until failure. A paired t test was used to assess differences between screws, with significance set at P < .05. RESULTS: Insertion and mechanical shear testing variables were comparable for AO and AP insertion equipment and screws. CONCLUSION: The 6.5-mm tapered AP screw can be inserted in equine third metacarpal condyles and is mechanically comparable with the 4.5-mm AO screw for fixation of a simulated lateral condylar fracture. CLINICAL RELEVANCE: Considering the comparable mechanical behavior, the potential for less-persistent soft-tissue irritation with the headless design, and the ability to achieve interfragmentary compression by inserting the screw in one hole drilled perpendicular to the fracture plane, the 6.5-mm tapered AP screw may be an attractive alternative for repair of incomplete lateral condylar fractures in horses.     

Polymerase chain reaction and DNA sequencing for detection of ovine herpesvirus 2 in American bison (Bison bison).

Serum samples were collected at slaughter from 226 24-30-month-old ranch-raised, clinically normal American bison (Bison bison) bulls from North Dakota, Minnesota, Kansas, and Manitoba to assess the presence of antibodies to ovine herpesvirus 2 (OHV-2). Antibodies to OHV-2 were detected by competitive inhibition enzyme-linked immunosorbent assay in 10 of 226 (4.40%) samples. Polymerase chain reaction (PCR) analysis of sera positive for OHV-2 DNA demonstrated a 238 kilobase fragment. The nucleotide sequence of the PCR-positive samples in comparison to the reported OHV-2 nucleotide sequence resulted in a homology range of 82.8-95.4%.     

Effect of Weight Gain and Subsequent Weight Loss on Glucose Tolerance and Insulin Response in Healthy Cats

The effects of weight gain and subsequent weight loss on glucose tolerance and insulin response were evaluated in 12 healthy cats. Intravenous glucose tolerance tests (IVGTT) were performed at entry into the study, after a significant gain of body weight induced by feeding palatable commercial cat food ad libitum, after a significant loss of body weight induced by feeding a poorly palatable purified diet to discourage eating and promote fasting, and after recovery from fasting when body weight had returned to pre-study values and cats were eating commercial foods. A complete physical examination with measurement of body weight was performed weekly, a CBC and serum biochemistry panel were evaluated at the time of each IVGTT, and a liver biopsy specimen obtained 2 to 4 days after each IVGTT was evaluated histologically for each cat. Mean serum glucose and insulin concentrations after glucose infusion and total amount of insulin secreted during the second 60 minutes and entire 120 minutes after glucose infusion were significantly (P > .05) increased after weight gain, as compared with baseline. At the end of weight loss, cats had hepatic lipidosis and serum biochemical abnormalities consistent with feline hepatic lipidosis. There was a significant (P > .05) increase in mean serum glucose concentration and t_1/2, and a significant (P > .05) decrease in mean serum insulin concentration and the glucose disappearance coefficient (K) after glucose infusion for measurements obtained after weight loss, compared with those obtained after weight gain and at baseline. Insulin peak response, insulino-genic index, and total amount of insulin secreted during the initial 10 minutes, 20 minutes, and 60 minutes after glucose infusion were decreased markedly (P > .05), compared with measurements obtained after weight gain and at baseline. In addition, the total amount of insulin secreted for 120 minutes after glucose infusion was decreased markedly (P > .05) in measurements obtained after weight loss, compared with those obtained after weight gain. At the end of recovery, all cats were voluntarily consuming food, serum biochemical abnormalities identified after weight loss had resolved, the number and size of lipid vacuoles in hepatocytes had decreased, and results of IVGTT were similar to those obtained at baseline. These findings confirmed the reversibility of obesity-induced insulin resistance in cats, and documented initial deterioration in glucose tolerance and insulin response to glucose infusion when weight loss was caused by severe restriction of caloric intake.     

Septic osteitis of the distal phalanx in foals: 22 cases (1995-2002)

OBJECTIVE: To determine the clinical characteristics and outcome of foals with septic osteitis of the distal phalanx. DESIGN: Retrospective case series. ANIMALS: 22 foals. PROCEDURES: Information obtained from medical records included signalment; clinical, laboratory, and radiographic findings; treatment method; and outcome. Foals included in the study had lameness referable to the foot, radiographic evidence of localized lysis or focal loss of bone density of the distal phalanx, and suppurative discharge or necrosis of the affected bone evident at surgery. Foals with a history or evidence of penetrating wounds or subsolar abscessation were excluded. RESULTS: Mean age of foals at initial evaluation was 40.8 days (range, 3 to 122 days). Twenty-one (95%) foals had lameness as the primary complaint. Lesions consistent with septic osteitis of the distal phalanx localized to specific areas of the bone on the basis of radiographic and surgical findings were located on the solar margin or toe (14/22 [64%]), extensor process (5/22 [23%]), and palmar or plantar process (3/22 [13%]). Hind limbs (18/26 [69%] affected limbs) were more frequently affected. Two foals had > 1 affected limb, 2 had additional sites of osteomyelitis, and 4 had concurrent septic arthritis. Surgical debridement and regional antimicrobial perfusion were performed during general anesthesia. Extensor process lesions were not debrided. Nineteen of 22 (86%) foals survived to be discharged from hospital, and 16 horses reached racing age. Eleven of 16 had race starts, of which 8 had official race starts and 3 had unofficial race starts. CONCLUSIONS AND CLINICAL RELEVANCE: Septic osteitis of the distal phalanx should be considered as a source of lameness in foals with signs referable to the foot and does not necessarily preclude a career in racing. Although infection may occur secondary to bacterial penetration of the hoof or sole, the distal phalanx should also be considered as a potential site for hematogenous septic arthritis or osteomyelitis in foals.