bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of endothelium and nitric oxide in the in vitro response of equine colonic venous rings to vasoconstrictor agents
Authors: Moore Rustin M. , Venugopalan Changaram S. , Sedrish Steven A. , Holmes Earnestine P. 
Published: January 2024

Abstract

Objective
To determine in vitro contractile responses of equine colonic veins to various vasoconstrictor agents.

Animals
Colonic veins collected from 8 adult horses.

Procedure
Veins were cut into 4-mm-wide rings, placed in organ baths at 37 C, and attached to a force-transducer interfaced with a polygraph; 2 g of tension was applied, and rings were allowed to equilibrate for 45 minutes. Bath solution was replaced, and tension was reapplied at 15-minute intervals. Cumulative concentration responses (10-8 to 10-4M) were determined for each agent, using separate rings (n = 8). Three vein groups were evaluated: endothelium-intact, endothelium-denuded, and Nω-nitro-L-arginine methyl ester (L-NAME, 10-5M)-treated. Maximal responses by each vein to each agent were considered 100%; responses to lower concentrations were calculated as percentage of maximum.

Results
Considering all vein groups, comparison of the doses that caused 50% of the maximal contraction revealed relative sensitivity of colonic veins to be: angiotensin II (ANG) > thromboxane B2 analogue (TXB) > 5-hydoxytryptamine (5HT) > norepinephrine (NE) > histamine (HST) > prostaglandin F2α (PGF) > vasopressin (VP). Compared with ANG, PGF, TXB, and VP, treatment with HST, 5HT, and NE evoked significantly greater responses. Endothelium-denuded and L-NAME-treated colonic veins had significantly greater maximal contractile responses than did endothelium-intact veins.

Conclusions
Response of colonic veins to vasoconstrictor agents was differential; sensitivity was not altered by endothelium removal or L-NAME treatment; maximal responses of endothelium-intact veins were greater than those of endothelium-denuded and L-NAME-treated veins; and responses of endothelium-denuded and L-NAME-treated veins were not different.

Clinical Relevance
Alterations in colonic veins that mimic conditions associated with large-colon volvulus may contribute to blood flow alterations, edema formation, and vascular responses to hypovolemic and endotoxic shock. (Am J Vet Res 1997;58:1145–1151)
Effects of Pasteurella haemolytica leukotoxin and lipopolysaccharide on histamine, prostanoid, and leukotriene release by bovine lung parenchyma in vitro
Authors: Saban Ricardo , Broadstone Richard V. , Haak-Frendscho Mary , Skoyen Sarah , Fialkowski James , Maheswaran Sam K. , Bjorling Dale E. , Czuprynski Charles 
Published: January 2024

SUMMARY

Objective
To identify the effect of Pasteurella haemolytica lipopolysaccharide (LPS) and leukotoxin (LKT) on spontaneous and calcium ionophore-induced histamine and inflammatory mediator release from isolated bovine lung parenchyma.

Sample Population
Lungs from 8 healthy cattle.

Procedure
Isolated bovine lung parenchyma was incubated in vitro for 2 hours with LKT or LPS, and spontaneous and induced release of inflammatory mediators was determined.

Results
LKT and LPS increased spontaneous release of histamine and leukotriene B4. In addition, incubation with LPS increased spontaneous release of prostaglandin E2. Moreover, a differential effect of the 2 toxins on calcium ionophore-induced inflammatory mediator release was observed. LKT specifically primed isolated lung parenchyma to release leukotriene B4 and thromboxane B2 in response to calcium ionophore, whereas LPS did not alter the profile of prostanoids released by bovine lung tissue exposed to calcium ionophore.

Conclusions
Pasteurella haemolytica toxins have a direct effect on bovine lung parenchyma, causing release of inflammatory mediators, which contribute to response to infection. Furthermore, bacterial toxins (LKT in this study) may sensitize tissues to the effects of other irritant stimuli, amplifying the inflammatory response. (Am J Vet Res 1997;58:1227–1231)
Pharmacokinetics of luxabendazole after oral and intravenous administration to sheep
Authors: Ortiz Ana I. , Álvarez-Bujidos Lucía , Ferre Ignacio , Ordóñez David 
Published: January 2024

SUMMARY

Objective
To determine pharmacokinetics of luxabendazole after oral and IV administration to healthy sheep.

Animals
7 clinically normal female Merino sheep between 9 and 12 months old.

Procedure
Pharmacokinetics were determined after oral and IV administration of luxabendazole at a dose of 10 mg/kg of body weight. Serial blood samples were collected for 56 hours after administration. Plasma concentrations of luxabendazole were determined by high-pressure liquid chromatography.

Results
After IV administration, elimination of luxabendazole was slow, with a mean half-life of 8.72 hours. Mean steady-state volume of distribution and mean distribution volume during the elimination phase were 3.18 and 3.10 L/kg, respectively. Mean clearance was 0.24 L/kg·h, and mean area under the concentration-time curve was 41.89 mg·h/L. After oral administration, luxabendazole was slowly absorbed from the gastrointestinal tract. Mean absorption half-life was 2.26 hours. Peak plasma concentration was 0.50 μg/ml and was detected 14 to 16 hours after drug administration. Mean area under the concentrationtime curve was 12.03 mg·h/L. Mean bioavailability was 29%.

Conclusions
Results suggest that luxabendazole is moderately absorbed from the gastrointestinal tract in sheep, is widely distributed into extravascular compartments, and is cleared slowly.

Clinical Relevance
Determination of pharmacokinetic parameters is the first step in determining a safe and efficacious dosage regimen for luxabendazole in sheep. (Am J Vet Res 1997;58:1263–1266)
Clinical evaluation of cimetidine, sucralfate, and misoprostol for prevention of gastrointestinal tract bleeding in dogs undergoing spinal surgery
Authors: Hanson Stephen Michael , Bostwick David Robert , Twedt David Cameron , Smith Mary Olivia 
Published: January 2024

SUMMARY

Objective
To determine the incidence of gastrointestinal (GI) tract bleeding in dogs undergoing spinal surgery with adjunct corticosteroid treatment, and to determine the protective efficacy of cimetidine, sucralfate, and misoprostol against such bleeding in these dogs.

Animals
40 dogs that underwent spinal surgery.

Procedures
Myelography and surgery were performed on the first or second day of hospitalization. Methylprednisolone sodium succinate was given at a dosage of 30 mg/kg of body weight prior to myelography, followed by a second full or half dose 2 to 4 hours later at clinician discretion. Spinal surgery was performed in conventional manner, postoperative administration of analgesics was done, and dogs were fed a diet lacking red meat. Dogs were assigned at random to 1 of the 3 treatment groups or to the control group. Dogs of the treatment groups received cimetidine, sucralfate, or misoprostol. Physical examination and determination of PCV and serum total protein values were performed daily. A fecal sample was examined daily for gross and occult blood.

Results
36 of 40 dogs had GI tract bleeding during a hospitalization period of 3 to 6 days. There was no significant difference in development of bleeding between the control group and any of the treatment groups.

Conclusions
Gastrointestinal tract bleeding occurred in 90% of dogs undergoing spinal surgery combined with administration of methylprednisilone sodium succinate, a higher rate than that found in previous studies. This bleeding was not life-threatening. Prophylactic benefit from any of the GI protectants tested was not found. (Am J Vet Res 1997;58:1320–1323)
Assessment of urinary bladder volume in dogs by use of linear ultrasonographic measurements
Authors: Atalan Gultekin , Barr Frances J. , Holt Peter E. 
Published: January 2024

SUMMARY

Objective
To evaluate accuracy of formulas derived from linear ultrasonographic measurements and used in human beings to assess urinary bladder volume as a method of estimating bladder volume in dogs and to test reproducibility of ultrasonographic measurements of linear bladder dimensions.

Animals
64 live dogs (for bladder volume determination) and 31 fresh canine cadavers (for ultrasonographic assessment of reproducibility of measurements).

Procedure
Maximal length, longitudinal and transverse depth (DL and DT), and width were measured from the maximal longitudinal and transverse images. Bladder volume was estimated, using 6 formulas, and calculated volumes were compared statistically with the actual volume obtained by catheterization, using paired nonparametric tests. Reproducibility of bladder dimensions was investigated by measuring length, DL, DT, and width 3 times from each image of section. Measurements of depth (DL and DT) also were compared.

Results
Calculations of bladder volume from linear dimensions, using a formula described for use in human beings, gave a satisfactory indication of actual bladder volume; the median difference between actual and calculated volumes was only 5 ml. Bladder volume estimations were less accurate when large-volume bladders were measured. Matching between repeated measurements was significant (P < 0.005 for longitudinal bladder length and P < 0.0001 for bladder depth and width). Measurements of DL and DT were significantly (P < 0.01) different, with DL greater than DT.

Conclusions
Ultrasonographic assessment of bladder volume in dogs by application of the formula is sufficiently accurate for most clinical purposes.

Clinical Relevance
Ultrasonography would be a useful method of estimating bladder volume in dogs with severe obstruction or dysfunctional voiding of urine. (Am J Vet Res 1998;59:10–15)
Myoelectric activity of the ileum, cecum, and right ventral colon, and cecal emptying of radiolabeled markers in clinically normal ponies
Authors: Lester Guy D. , Merritt A. M. , Neuwirth Lisa , Vetro-Widenhouse Tamara , Steible Christine , Rice Brett , Mauragis Danielle F. , Madison John B. 
Published: January 2024

Abstract

Objectives
To determine normal cecal emptying curves for liquid- and solid-phase radiolabeled markers and to further define myoelectric patterns of the ileum, cecum, and colon in healthy ponies.

Animals
6 adult ponies.

Procedure
A cecal cannula and 12 bipolar Ag-AgCl recording electrodes were sutured to the ileum, cecum, and right ventral colon of the ponies. Radioisotopes, indium 111-labeled diethyltriaminepentaacetic acid (111In-DTPA) and technetium 99m (99mTc)-labeled sulfur colloid bound to egg albumen, were introduced through the cannula directly into the cecal body. Movement of these markers from the cecum was monitored by a gamma camera, and power exponential clearance curves were generated. Myoelectric data were collected before and after IV administration of isotonic saline (0.9% NaCl) solution, and were analyzed for spike burst (SB) rate, relative activity index, and mean burst duration. Myoelectric complexes were identified from observation of chart recordings or compressed, digitized data.

Results
Clearance curves were generated for liquid (111In-DTPA)- and solid (99mTc)-phase markers. Marker types were not different with respect to lag phase, but liquid markers emptied at a slightly faster rate than did solids. Baseline values were calculated after saline solution administration for each of the myoelectric variables investigated. A relation between ileal, cecal, and colonic myoelectric activity was identified. Activity consistent with the previously described colonic migrating myoelectric complex in the pelvic flexure was identified in the right ventral colon.

Conclusions and Clinical Relevance
Baseline data on normal cecal emptying was obtained; this technique could be used to evaluate the effect of postulated motility-modifying treatments used in equine practice. (Am J Vet Res 1998;59:313–319)
Effects of stress resulting from short-term restraint on in vitro functional capacity of leukocytes obtained from pigs
Authors: Magnusson Ulf , Wattrang Eva , Tsuma Victor , Fossum Caroline 
Published: January 2024

Abstract

Objective
To investigate whether the procedure used to snare and restrain pigs during collection of blood samples would alter in vitro functional capacity of leukocytes in the samples.

Animals
8 gilts.

Procedure
Catheters were surgically inserted into the jugular vein of gilts to enable blood sample collection without restraint. After collection of a control sample, gilts were restrained by use of a snare and samples were collected at 0.5, 3.5, and 6.5 minutes after start of restraint (0 minutes). At each time point, plasma β-endorphin and cortisol concentrations as well as WBC counts were recorded, and functional capacity of leukocytes in cultures of whole blood was assessed by means of mitogen-induced proliferation and interleukin-2 activity, virus-induced interferon-α concentration, and phagocytosis of zymosan particles.

Results
Concentrations of plasma β-endorphin and cortisol were increased at 3.5 and 6.5 minutes after start of restraint. At these times, virus-induced interferon-α concentration was decreased, whereas proliferative response to Concanavalin A and phytohemagglutinin increased in samples collected at 6.5 minutes.

Conclusion and Clinical Relevance
It was possible to snare pigs for the purpose of collecting blood samples and restrain them without causing excessive stress that would affect immunologic variables, provided that the collection procedure was completed within a few minutes. (Am J Vet Res 1998;59:421–425)
Ultrasonographic assessment of bladder neck mobility in continent bitches and bitches with urinary incontinence attributable to urethral sphincter mechanism incompetence
Authors: Atalan Gultekin , Holt Peter E. , Barr Frances J. 
Published: January 2024

Abstract

Objective
To determine bladder neck positional changes between standing and recumbent positions in bitches and whether change is related to continence status or general anesthesia, or both, and to evaluate reproducibility of measurements.

Animals
45 continent animals and 46 incontinent bitches with urethral sphincter mechanism incompetence (SMI).

Procedure
Distance between the bladder neck and perineal skin was measured ultrasonographically via the perineum while each dog was conscious in standing and right lateral recumbency and in right lateral recumbency under general anesthesia. Measurements of the bladder neck position obtained in right lateral recumbency under anesthesia were compared with radiographic measurements of the same parameter. Reproducibility of the ultrasonographic measurements of the distance between bladder neck and perineum was assessed on 3 occasions for each position in 50 dogs.

Results
In all dogs, differences in bladder neck position between standing and recumbent conscious-associated positions were not significant. However, caudal bladder neck movement between standing conscious- and recumbent anesthesia-associated positions and between recumbent conscious- and anesthesia-associated positions was significant for all dogs. Incontinent bitches had greater degree of caudal bladder movement during anesthesia. Mean difference in bladder neck positions between recumbent conscious- and recumbent anesthesia-associated positions was 0.24 cm in continent, compared with 0.73 cm in incontinent, bitches. Radiographic measurements were significantly greater than ultrasonographic measurements. Differences between repeated measurements for standing position were not significant, but those for recumbent conscious- and recumbent anesthesia-associated positions were significant.

Conclusions
Additional vesicourethral support mechanisms in continent dogs, are deficient in bitches with SMI, allowing the bladder neck to move further caudad. (Am J Vet Res 1998;59:673-679)
Effects of medetomidine on serum osmolality; urine volume, osmolality and pH; free water clearance; and fractional clearance of sodium, chloride, potassium, and glucose in dogs
Authors: Burton Shelley , Lemke Kip A. , Ihle Sherri L. , Mackenzie Allan L. 
Published: January 2024

Abstract

Objective
To determine effects of IV medetomidine administration on selected clinicopathologic variables in dogs.

Animals
6 healthy adult Beagles.

Procedure
Dogs were randomly assigned to each of 3 treatments in a crossover study design. Serum osmolality, urine osmolality, urine pH, and fractional clearances of sodium, chloride, potassium, and glucose were determined before and 20, 40, 60, 120, 180, 240, 300, 360, 420, and 480 minutes after IV administration of 0.9% NaCl (saline) solution (control) or medetomidine (10 or 20 μg/kg of body weight). The urinary bladder was emptied prior to saline or medetomidine administration, and urine volume was determined at the same posttreatment times as those described previously. Free water clearance was calculated for all posttreatment times.

Results
After medetomidine administration, serum osmolality, urine volume, free water clearance, and fractional clearance of potassium and glucose increased; urine osmolality decreased. Initially, urine pH and fractional clearance of chloride decreased, then subsequently increased. Fractional clearance of sodium did not change.

Conclusions and Clinical Relevance
Because IV administration of medetomidine to dogs at dosages of 10 and 20 μg/kg induces a diuretic effect that lasts up to 4 hours, the drug should be used with discretion in hypovolemic or dehydrated dogs, and its use should be avoided in those with urinary tract obstruction. (Am J Vet Res 1998;59:756-761)
Detection of feline herpesvirus 1 DNA in corneas of cats with eosinophilic keratitis or corneal sequestration
Authors: Nasisse Mark P. , Glover Tony L. , Moore Cecil P. , Weigler Benjamin J. 
Published: January 2024

SUMMARY

Objective
To determine whether feline herpesvirus 1 (FHV-1) DNA is in the corneas of clinically normal cats and cats with eosinophilic keratitis or corneal sequestration.

Sample Population
Corneal biopsy specimens obtained from cats referred for treatment of corneal sequestration or eosinophilic keratitis.

Procedure
Corneal scraping or keratectomy specimens collected from clinically normal cats, cats with eosinophilic keratitis, and cats with corneal sequestration were evaluated for FHV-1 DNA by use of polymerase chain reaction (PCR). DNA was extracted from the tissue, and 1 μg was assayed for FHV-1 by use of a single-round (40 cycles) PCR assay with primers directed at a 322-bp region of the thymidine kinase gene. Polymerase chain reaction positivity for clinically normal and affected cats of various breeds was compared by χ2 analysis at α = 0.05.

Results
The FHV-1 DNA was detected in 5.9% (1/17) of corneas from clinically normal cats, in 55.1% (86/156) of corneal sequestra, and in 76.3% (45/59) of scraping specimens from cats with eosinophilic keratitis. Prevalence was significantly (P < 0.001) greater for cats with corneal sequestration or eosinophilic keratitis than for clinically normal cats. For cats with corneal sequestration, prevalence of FHV-1 DNA was significantly lower in Persian and Himalayan, compared with domestic shorthair and longhair breeds.

Conclusion
Data strongly imply involvement of FHV-1 in the pathogenesis of eosinophilic keratitis and corneal sequestration. In Persian and Himalayan breeds, however, other nonviral factors also appear to be involved.

Clinical Relevance
Feline herpesvirus 1 must be considered when treating cats with corneal sequestration or eosinophilic keratitis. (Am J Vet Res 1998;59:856–858)
Regional distribution of blood flow in the brain of horses at rest and during exercise
Authors: Manohar Murli , Goetz Thomas E. 
Published: January 2024

SUMMARY

Objective
To examine regional distribution of blood flow in the brain of horses at rest and during exercise.

Animals
9 clinically normal horses.

Procedure
Regional brain blood flow was measured using radionuclide-labeled 15-μm-diameter microspheres injected into the left ventricle, while reference blood samples were obtained from the aorta.

Results
At rest, cerebral cortex and caudate nuclei received significantly higher blood flow, compared with cerebral white matter. A similar perfusion heterogeneity existed in the cerebellum. In the brain stem, a gradual tapering of blood flow from thalamus-hypothalamus towards medulla was observed in standing horses. Progressive significant increases in heart rate and in aortic and right atrial pressures occurred during exercise at 8 and 13 m/s, and horses developed significant arterial hypoxemia and hypercapnia. Cerebral and cerebellar gray- to white-matter perfusion heterogeneity was maintained during exercise, indicating differential metabolic O2 needs. Despite arterial hypoxemia, hypercapnia, and hypertension, exercise did not result in significant changes in blood flow to the cerebral cortex and caudate nuclei whereas, in cerebral white matter, a significant decrease in blood flow was observed. In all cerebral tissues, vascular resistance increased during exercise, indicating autoregulation of cerebral blood flow. In the cerebellar cortex, blood flow increased significantly with strenuous exercise as vasodilation occurred. Vascular resistance in cerebellar white matter increased during exercise at 13 m/s. Blood flow in the medulla, pons, midbrain, and thalamus-hypothalamus was not significantly altered during exercise from that at rest.

Conclusion
Despite arterial hypoxemia, hypercapnia, and hypertension, autoregulation of cerebral and cerebellar blood flow is maintained in horses during exercise. (Am J Vet Res 1998;59:893–897)
Functional anatomy of the cartilage of the distal phalanx and digital cushion in the equine foot and a hemodynamic flow hypothesis of energy dissipation
Authors: Bowker Robert M. , Van Wulfen Kimberly K. , Springer Susan E. , Linder Keith E. 
Published: January 2024

Abstract

Objectives
To examine macro- and microscopic characteristics of cartilage of the distal phalanx (ungual cartilage [UC]) and digital cushion in the equine foot and to relate them to the foot's function of energy dissipation.

Animals
85 horses and 5 foals of various breeds and ages.

Procedure
Feet, obtained at necropsy, were perfused with India ink (n = 30), latex (5), or polymer plastic (10). Select feet were examined histologically for tissue architecture and to identify elastic fibers. Immunochemistry to identify substance P peptides in nerves (feet from foals) and gold chloride impregnation of axons (n = 10) were performed. Feet were sectioned transversely (n = 27) or coronally (62 feet in a matched-paired study). Ungual cartilage was measured at the navicular bone. Digital cushions were examined for relative tissue composition between forefeet and hind feet.

Results
Ungual cartilage formed an axial projection that extended towards the midline to overlie the bars, and dorsally along the semilunar line of the distal phalanx. Ungual cartilage of forefeet was significantly larger than that of hind feet. The digital cushion was composed of fat and elastic tissues in feet with thin UC, or fibrous and fibrocartilaginous tissue and elastic tissue in feet with thicker UC. Sensory nerves and an extensive network of venovenous anastomoses were found in the UC.

Conclusions and Clinical Relevance
Ungual cartilage and the digital cushion provide the basis for a hemodynamic flow hypothesis of energy dissipation. Maximum energy dissipation depends on proper hoof preparation and shoeing. (Am J Vet Res 1998;59:961–968)