Life history traits and trade-offs between two species of the ascochyta blight disease complex of pea

Plant disease complexes are a playground to investigate coinfections in natural or cultivated systems. Pathogens of such complexes may affect each other through direct and/or indirect interactions and lead to changes in virulence or aggressiveness, offspring production, and transmission. As coinfections by sympatric host-pathogens can strongly influence pathogen dynamics and their evolutionary trajectories, new insights into the mechanisms of their coexistence is thus of critical importance. In order to characterize differences in ecological niches liable to explain species coexistence on the same host, the inter- and intraspecific diversity of the life history traits in natural collections of the two main pathogens (Peyronellaea (formerly Didymella) pinodes [Dp] and Phoma medicaginis var. pinodella [Pmp]) of the ascochyta blight disease complex of pea was evaluated under controlled conditions. Dp strains developed 1.3 times faster and produced longer, mainly bicellular spores and in lower amounts (3.7 times less) than Pmp strains. Pmp strains were separated into two groups, one producing more pycnidiospores, mainly bicellular, with less resources, and the other with mainly unicellular ones. These three groups can be interpreted as three distinct life history strategies: pioneer colonizer (Dp), scavenger (large-spored Pmp), and intermediate (small-spored Pmp), allowing differentiation in access to and use of resources. While this experimental work provides new insight into coexistence of two species of the ascochyta blight disease complex of pea, it also raises the question of the benefit of having two distinct life history strategies for one species (Pmp).     

Efficacy and cardiorespiratory effects of lumbosacral intrathecal 2% procaine and 2% xylazine with or without sedation in calves undergoing umbilical surgery

ABSTRACT

Aims: To compare the effects of intrathecal anaesthesia using procaine and xylazine, with and without sedation with I/V xylazine and butorphanol, on sedation and cardiorespiratory measures in calves undergoing umbilical surgery.

Methods: Male dairy calves, aged <3 months, were recruited that had enlargement of the umbilical stalk which was abnormal when palpated. They were assigned to receive either intrathecal injection between the sixth lumbar and first sacral vertebrae of 4?mg/kg of 2% procaine and 0.2?mg/kg 2% xylazine, with I/V injection of 0.02?mg/kg xylazine and 0.1?mg/kg of butorphanol (IT?+?SED group; n?=?6), or the same intrathecal injection and I/V injection of 0.9% saline (IT group; n?=?7). Surgery to correct abnormalities was carried out with calves positioned in dorsal recumbency. Rescue analgesia with injections of 2% procaine around the surgical wound was administered when movements triggered by surgery were observed. Post-operative analgesia was provided using I/V 0.5?mg/kg meloxicam. Duration of surgery was recorded, as well as degree of sedation, heart rate, systolic (SAP), diastolic (DAP) and mean (MAP) arterial blood pressure during surgery.

Results: All anaesthetic and surgical procedures were successfully performed. Mean total duration of surgery was similar for the IT?+?SED and the IT groups (30.33 (SD 10.09) and 31.00 (SD 10.21) minutes, respectively) (p?=?0.92). All calves were at least mildly sedated from 5 minutes after injections to the end of the surgery. One calf in the IT?+?SED group and three calves in the IT group required rescue analgesia when the umbilicus was manipulated. Between 0 and 10–15 minutes after injection, decreases in mean heart rate, SAP, MAP and DAP were observed in both groups. Mean SAP was lower in the IT?+?SED than the IT group. Hypotension (MAP<60?mm Hg) was present in four calves from the IT?+?SED group and in one from the IT group.

Conclusions and clinical relevance: Intrathecal administration of 2% procaine and 2% xylazine allowed the successful completion of umbilical surgery, but 30% of calves needed rescue analgesia during surgery. Clinically, the addition of I/V sedation seemed to provide better analgesia than intrathecal block alone but resulted in greater hypotension.     

Comparison of medetomidine—morphine and medetomidine—methadone for sedation,isoflurane requirement and postoperative analgesia in dogs undergoing laparoscopy

Objective

To compare the effects of intravenous (IV) medetomidine-morphine and medetomidine-methadone on preoperative sedation, isoflurane requirements and postoperative analgesia in dogs undergoing laparoscopic surgery.

Cardiopulmonary effects of controlled versus spontaneous ventilation in pigeons anesthetized for coelioscopy

OBJECTIVE: To evaluate the cardiorespiratory effects of controlled versus spontaneous ventilation in pigeons anesthetized for coelioscopy. DESIGN: Prospective study. ANIMALS: 30 healthy adult pigeons (Columbia livia). PROCEDURE: During isoflurane anesthesia, 15 pigeons were allowed to breathe spontaneously (SP group) and 15 were mechanically ventilated (MV group) by use of a pressure-limited ventilator. In each group, cardiopulmonary variables (including end-tidal CO2 concentration [ETCO2]) were measured before (baseline), during, and after coelioscopy. An arterial blood sample was collected for blood gas analyses from each pigeon before coelioscopy and after the procedure, when the caudal thoracic air sac was still open. RESULTS: At baseline, hypoventilation was greater in the SP group than the MV group. Compared with the SP group values, ETCO2 overestimated PaCO2 to a greater degree in the MV group. Cardiovascular variables were not different between groups. After coelioscopy (when the air sac was open), PaCO2 had decreased significantly from baseline in the MV group. In the SP group, hypoventilation worsened despite an increase in respiratory rate. After coelioscopy, PaO2 in the SP group had decreased from baseline and was lower than PaO2 in the MV group; arterial blood pressure and heart rate in the MV group had decreased from baseline and were lower than values in the SP group. CONCLUSIONS AND CLINICAL RELEVANCE: In adult pigeons, controlled ventilation delivered by a pressure-limited device was not associated with clinically important adverse cardiopulmonary changes but may be associated with respiratory alkalosis and cardiovascular depression when air sac integrity has been disrupted.     

The effects of two endotracheal tube cuff inflation pressures on liquid aspiration and tracheal wall damage in horses

OBJECTIVE: To investigate the effect of endotracheal tube cuff inflation pressure on the occurrence of liquid aspiration and tracheal wall damage. STUDY DESIGN: Prospective, randomized experimental study. ANIMALS: Ten healthy horses, weighing 535 +/- 55 kg. METHODS: Horses were anesthetized, orotracheally intubated, placed in dorsal recumbency, and maintained on isoflurane in oxygen with controlled ventilation for 175 +/- 15 minutes. The horses were randomly assigned to an endotracheal cuff pressure of 80-100 or 120 cm H2O. The cuff pressure was continuously monitored and maintained at a constant pressure. Methylene blue in saline was instilled proximal to the cuff. After euthanasia, the trachea was opened distal to the endotracheal tube tip to check for evidence of dye leaking past the cuff. The cervical trachea was then resected and opened longitudinally for gross and histologic examinations. RESULTS: No blue staining was found distal to the cuff in any horse. Visual examination of the tracheal mucosa revealed hyperemic and hemorrhagic lesions at the site of the cuff contact. Histologic changes included epithelium attenuation or erosion, submucosal neutrophilic infiltration, and submucosal hemorrhages. Lesions were absent or less extensive in the lower cuff pressure group as compared to the high cuff pressure group. CONCLUSIONS: The endotracheal tube cuff produced a seal sufficient to prevent leakage in both groups. Tracheal wall damage was more severe and occurred more frequently in the higher cuff pressure group. CLINICAL RELEVANCE: Tracheal mucosal damage induced by cuff inflation is pressure-dependent. Cuff pressure monitoring is recommended.     

The innate immune response of equine bronchial epithelial cells is altered by training

Respiratory diseases, including inflammatory airway disease (IAD), viral and bacterial infections, are common problems in exercising horses. The airway epithelium constitutes a major physical barrier against airborne infections and plays an essential role in the lung innate immune response mainly through toll-like receptor (TLR) activation. The aim of this study was to develop a model for the culture of equine bronchial epithelial cells (EBEC) in vitro and to explore EBEC innate immune responses in trained horses. Bronchial epithelial biopsies were taken from 6 adult horses during lower airway endoscopy. EBEC were grown in vitro by an explant method. The innate immune response of EBEC was evaluated in vitro by treatment with TLR ligands. TLR3 is the most strongly expressed TLR at the mRNA level in EBEC and stimulation of EBEC with Poly(I:C), an analog of viral dsRNA, triggers a strong secretion of IFN-β, TNF-α, IL-6 and CXCL8. We further evaluated the EBEC innate immune response in horses that underwent a 4-month-training program. While training had no effect on TLR mRNA expression in EBEC as well as in bronchial biopsies, it increased the production of IFN-β after stimulation with a TLR3 ligand and decreased the secretion of TNF-α and IL-6 after stimulation with a TLR2 and TLR3 ligand. These findings may be implicated in the increased risk for viral and bacterial infections observed in sport horses. Altogether, we report a successful model for the culture of EBEC that can be applied to the investigation of pathophysiologic conditions in longitudinal studies.     

Endotracheal intubation in horses: a study of two cuff inflation pressures, correlation with liquid aspiration, and tracheal wall damage

Nine adult horses were anesthetized for a nonsurvival abdominal adhesion study. Horses were randomly assigned into two groups to receive endotracheal tube cuff pressures of either 80 cm H₂O (Group P80) or 120 cm H₂O (Group P120). After intubation (Bivona 30 mm ID), anesthesia was maintained with isoflurane. Horses were ventilated 10 times per minute with a suitable inspiratory pressure to maintain Pe ′CO₂ in the 35–40 mm Hg (4.7–6.0 kPa) range. Cuff pressure was continuously monitored with a pressure transducer (TruWave, Baxter) calibrated to the atmospheric pressure and maintained at a constant pressure. Twenty‐five millilitres of methylene blue dye in saline were instilled proximal to the cuff over 5 minutes. The horses were euthanized 123 ± 23 minutes later (mean ± SD). Immediately, the trachea was opened distal to the tip of the endotracheal tube, and the mucosa was observed for evidence of dye leaking past the cuff. The cervical trachea was resected and the lumen exposed by a ventral longitudinal incision. Biopsies (1–2 rings) were obtained at mid‐cuff level and distal to the tip of the endotracheal tube, and placed in formalin for later histologic examinations (H&E stain). Methylene blue stain was not observed distal to the endotracheal tube cuff in any horse. Visual examination of the tracheal mucosa revealed hyperemic or hemorrhagic lesions at the level of cuff contact both ventrally and dorsally. Histologic changes included epithelium damage, submucosal neutrophil infiltrates, and acute submucosal hemorrhages. P80 horses had none or focal to multifocal lesions on the ventral and dorsal aspects of the rings. P120 horses had multifocal to diffuse lesions on all aspects (dorsal, ventral, and lateral). We concluded that the endotracheal tube cuff produced a seal sufficient to prevent leakage at both pressures. Tracheal damages on gross and microscopic examinations were more severe and occurred more frequently at the higher cuff pressure.     

Efficacy of preanesthetic intramuscular administration of ephedrine for prevention of anesthesia-induced hypotension in cats and dogs

To determine if the preanesthetic administration of ephedrine would prevent anesthesia-induced hypotension in dogs and cats, 10 cats were anesthetized with acepromazine, butorphanol, ketamine, and isoflurane, and 8 dogs were anesthetized with acepromazine, morphine, propofol, and halothane. Cats received ephedrine or saline 10 minutes after premedication. Dogs received ephedrine or saline at the time of premedication. Systolic arterial blood pressure, respiratory rate, heart rate, end-tidal CO₂, O₂ saturation, cardiac rhythm, and rectal temperature were recorded.