Standard plant bioassays for toxicity assessment of urban soils with complex xenobiotic profile

We have assessed the toxicity of urban soil with a complex xenobiotics profile incorporating persistent organic pollutants using standard plant biotesting with Latuca sativa (L.) lattice and Triticum aestivum (L.) wheat. Analysis of adjoint variations of the certain endpoints that characterize the growth parameters allowed one to reveal and qualitatively define the tested activity as being similar to the functional effects of some phytoregulators. No correlation was revealed between the level of the tested activity expressed with the indicated endpoints and the concentrations/sum of concentrations of xenobiotics profile components.     

Formation of wall openings in root cells of Arabidopsis thaliana following infection by the plant-parasitic nematode Heterodera schachtii

The induction and differentiation of feeding structures (syncytia) of the cyst nematode Heterodera schachtii in roots of Arabidopsis thaliana is accompanied by drastic cellular modifications. We investigated the formation of cell wall openings which occurred during syncytium differentiation. At the beginning of syncytium induction, a callose-like layer was deposited inside of the wall of the initial syncytial cell (ISC). First wall dissolutions developed by gradual widening of plasmodesmata between the ISC and neighbouring cells. As a general thickening of syncytial cell walls blocked existing plasmodesmata, other large openings were formed by enzymatic dissolution of intact walls by putative cellulase activity.     

Clinical findings in dogs and cats with lead poisoning

Over an 11-year period, 68 cases of lead poisoning were diagnosed in dogs and three in cats, accounting for 58.6% and 21.4% of the accidental poisonings in dogs and cats, respectively, presented at the Small Animal Clinic, University of Queensland. Of the dogs, 94% showed alimentary tract involvement and 67.6% central nervous system signs. Blood lead concentrations above 0.3 ppm were considered to indicate toxicity when associated with alimentary tract or central nervous system abnormalities. The percutaneous absorption of lead in dogs is proposed as a factor for intoxication.     

Pharmacokinetics of oral terbinafine in adult horses

The primary study objective was to compare the pharmacokinetics of p.o. terbinafine alone to p.o. terbinafine administered with p.o. cimetidine in healthy adult horses. The second objective was to assess the pharmacokinetics of terbinafine when administered per rectum in two different suspensions at 30 mg/kg to adult horses. Six healthy adult horses were included in this crossover study. Plasma terbinafine concentrations were quantified with liquid chromatography and mass spectrometry. The half‐life (geometric mean) was 8.38 and 10.76 h, for p.o. alone and p.o. with cimetidine, respectively. The mean maximum plasma concentrations were 0.291 μg/mL at 1.54 h and 0.418 μg/mL at 1.28 h for p.o. alone and p.o. with cimetidine, respectively. Terbinafine with cimetidine had an average C_MAX 44% higher and the relative F was 153% compared p.o. terbinafine alone, but was not statistically different (P > 0.05). Terbinafine was infrequently detected when administered per rectum in two different suspensions (water or olive oil). Minor adverse effects included oral irritation, fever, and colic. All resolved spontaneously. More pharmacokinetic studies are indicated assessing drug–drug interactions and using multiple dosing intervals to improve our knowledge of effective oral dosing, the potential for drug accumulation, and systemic adverse effect of terbinafine in horses.     

Impact of grassland contract policy on soil organic carbon losses from alpine grassland on the Qinghai–Tibetan Plateau

Carbon storage in the soils on the Qinghai–Tibetan Plateau plays a very important role in the global carbon budget. In the 1990s, a policy of contracting collective grasslands to smaller units was implemented, resulting in a change from the traditional collective grassland management to two new management patterns: a multi‐household management pattern (MMP: grassland shared by several households without enclosures) and a single‐household management pattern (SMP: grassland enclosed and used by only one household). In 2016, 50 MMP and 54 SMP winter pastures on the Qinghai–Tibetan Plateau were sampled to assess the differences in soil organic carbon (SOC) between the two management patterns. Results showed that average SOC was significantly greater under MMP than under SMP, with an estimated 0.41 Mg C/ha/yr lost due to SMP following the new grassland contract. Based on the government's grassland policy, four grassland utilization scenarios were developed for both summer and winter pastures. We found that if the grassland were managed under SMP, likely C losses ranged between 0.31 × 10⁷ and 6.15 × 10⁷ Mg C/yr across the Qinghai–Tibetan Plateau relative to MMP, which more closely resembles pre‐1990s grassland management. Previous estimates of C losses have only considered land use change (with cover change) and ignored the impacts driven by land management pattern changes (without cover change). The new data suggest that C losses from the Qinghai–Tibetan Plateau are greater than previously estimated, and therefore that the grassland contract policy should be reviewed and SMP households should be encouraged to reunite into the MMP. These findings have potential implications for land management strategies not only on the Qinghai–Tibetan Plateau but also other grazing regions globally where such practices may exist.     

Metabolic and mitogenic activities of insulin-like growth factor-1 in interleukin-1-conditioned equine cartilage

OBJECTIVE: To determine response of interleukin-1alpha (IL-1alpha)-conditioned equine articular cartilage explants to insulin-like growth factor-1 (IGF-1). Sample Population-Cartilage from the trochlea and condyles of the femur of a clinically normal 4-year-old horse. PROCEDURE: Effects of IGF-1 (0 to 500 ng/ml) after addition of IL-1alpha were evaluated by assessing matrix responses, using a sulfated glycosaminoglycan (GAG) assay, matrix 35SO4 GAG incorporation, and release of GAG. Mitogenic response was assessed by 3H-thymidine incorporation into DNA and fluorometric assay of total DNA concentration. RESULTS: Human recombinant IL-1alpha (40 ng/ml) increased the amount of labeled GAG released and decreased labeled and total GAG remaining in explants, and IL-1alpha decreased mitogenic response. Addition of IGF-1 counteracted effects seen with IL-1alpha alone. In general, IGF-1 decreased total and labeled GAG released into the medium, compared with IL-1alpha-treated explants (positive-control sample). Values for these variables did not differ significantly from those for negative-control explants. A significant increase in total and newly synthesized GAG in the explants at termination of the experiment was observed with 500 ng of IGF-1/ml. Labeled GAG remaining in explants was greater with treatment at 50 ng of IGF-1/ml, compared with treatment with IL-1alpha alone. Concentrations of 200 ng of IGF-1/ml abolished actions of IL-1alpha and restored DNA synthesis to values similar to those of negative-control explants. CONCLUSIONS AND CLINICAL RELEVANCE: IGF-1 at 500 ng/ml was best at overcoming detrimental effects associated with IL-1alpha in in vitro explants. These beneficial effects may be useful in horses with osteoarthritis.     

Influence of Cholinergic Blockade on the Development of Epinephrine-Induced Ventricular Arrhythmias in Halothane- and Isoflurane-Anesthetized Dogs

The arrhythmogenic effects of anesthetic drugs are assessed using the arrhythmogenic dose of epinephrine (ADE) model. The purpose of this study was to determine the influence of cholinergic blockade (CB) produced by glycopyrrolate (G) on ADE in 1.5 minimum alveolar concentration (MAC) halothane (H)- and isoflurane (I)-anesthetized dogs. Eight dogs (weighing between 12.5 and 21.5 kg) were randomly assigned to four treatment groups (H, HG, I, and IG) and each treatment was replicated three times. Anesthesia was induced and maintained with H (1.31%, end-tidal [ET]) or I (1.95%, ET) in oxygen. Ventilation was controlled (carbon dioxide [PCO₂] 35 to 40 mmHg, ET). G was administered 10 minutes before ADE determination at a dose of 22 μg/kg (11 μg/kg, intravenous [IV] and 11 μg/kg, intramuscular [IM]). The ADE was determined by IV infusion of epinephrine at sequentially increasing rates of 1.0, 2.5, and 5.0 μg/kg/min; and defined as the total dose of epinephrine producing at least four ectopic ventricular contractions (EVCs) within 15 seconds during a 3-minute infusion and up to 1 minute after the end of the infusion. Total dose was calculated as the product of infusion rate and time to arrhythmia. Data were analyzed using a randomized complete block analysis of variance. When significant (P < .05) F values were found a least significant difference test was used to compare group means. Values are reported as means ± standard error. The ADE (μg/kg) for H, HG, I, and IG were 1.53 ± 0.08, 3.37 ± 0.46, 1.61 ± 0.21, and > 15.00, respectively. Heart rates (HRs) (beats/min) and systolic pressures (mmHg) at the time of arrhythmia formation for H, HG, I, and IG were (60.3 ±4.0 and 142.0 ± 7.6), (213.0 ± 13.1 and 239.2 ± 7.1), (62.9 ± 4.5 and 151.9 ± 6.3), and (226.3 ± 6.1 and 323.5 ± 3.4), respectively. The H and I ADE were not different. The HG ADE was significantly less than the IG ADE. The H and I ADE were significantly less than the HG and IG ADE. We conclude the following from the results of this study of epinephrine infusion in halothane- and isoflurane-anesthetized dogs: (1) two distinct mechanisms are responsible for the development of arrhythmias, (2) CB produced by G significantly increases ADE but is associated with higher rate pressure products (RPP) and myocardial work, and (3) ADE methodology could be improved by determining ADE with and without CB.