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Electrochemical reduction of azo dyes mimicking their biotransformation to more toxic products النص الكامل
2019
Pietruk, Konrad | Piątkowska, Marta | Olejnik, Małgorzata
Electrochemical reduction of azo dyes mimicking their biotransformation to more toxic products النص الكامل
2019
Pietruk, Konrad | Piątkowska, Marta | Olejnik, Małgorzata
Some azo dyes, including Sudans I–IV and Para Red, are genotoxic and may be biotransformed to cancerogenic aromatic amines. They are banned as food and feed additives, but their presence has been detected in food. Aromatic amines are also considered potentially toxic. Online EC–MS is a promising tool to study the transformation mechanisms of xenobiotics such as azo dyes. The aim of the study was to investigate emulation of how azo dyes are enzymatically transformed to amines with EC–MS. The reduction reactions of five azo dyes (Sudans I–IV and Para Red) were conducted using a glassy carbon working electrode and 0.1% formic acid in acetonitrile. Reduction results were compared with the literature and in silico to select preliminary candidates for metabolites. The LC-MS/MS method was used to confirm results obtained by electrochemical reactor. A limited number of pre-selected compounds were confirmed as azo dyes metabolites – aniline for Sudan I, aniline and 4-aminoazobenzene for Sudan III, o-toluidine for Sudan IV, and 4-nitroaniline for Para Red. No metabolites were found for Sudan II. Electrochemistry–mass spectrometry was successfully applied to azo dyes. This approach may be used to mimic the metabolism of azo dyes, and therefore predict products of biotransformation.
اظهر المزيد [+] اقل [-]Electrochemical reduction of azo dyes mimicking their biotransformation to more toxic products النص الكامل
2019
Pietruk Konrad | Piątkowska Marta | Olejnik Małgorzata
Some azo dyes, including Sudans I–IV and Para Red, are genotoxic and may be biotransformed to cancerogenic aromatic amines. They are banned as food and feed additives, but their presence has been detected in food. Aromatic amines are also considered potentially toxic. Online EC–MS is a promising tool to study the transformation mechanisms of xenobiotics such as azo dyes. The aim of the study was to investigate emulation of how azo dyes are enzymatically transformed to amines with EC–MS.
اظهر المزيد [+] اقل [-]Comparison of intraosseous pentobarbital administration and thoracic compression for euthanasia of anesthetized sparrows (Passer domesticus) and starlings (Sturnus vulgaris) النص الكامل
2017
Paul-Murphy, Joanne R. | Engilis, Andrew Jr | Pascoe, Peter J. | Williams, Colette | Gustavsen, Kate A. | Drazenovich, Tracy L. | Keel, Kevin | Polley, Tamsen M. | Engilis, Irene E.
OBJECTIVE To compare intraosseous pentobarbital treatment (IPT) and thoracic compression (TC) on time to circulatory arrest and an isoelectric electroencephalogram (EEG) in anesthetized passerine birds. ANIMALS 30 wild-caught adult birds (17 house sparrows [Passer domesticus] and 13 European starlings [Sturnus vulgaris]). PROCEDURES Birds were assigned to receive IPT or TC (n = 6/species/group). Birds were anesthetized, and carotid arterial pulses were monitored by Doppler methodology. Five subdermal braided-wire electrodes were used for EEG. Anesthetic depth was adjusted until a continuous EEG pattern was maintained, then euthanasia was performed. Times from initiation of euthanasia to cessation of carotid pulse and irreversible isoelectric EEG (indicators of death) were measured. Data (medians and first to third quartiles) were summarized and compared between groups within species. Necropsies were performed for all birds included in experiments and for another 6 birds euthanized under anesthesia by TC (4 sparrows and 1 starling) or IPT (1 sparrow). RESULTS Median time to isoelectric EEG did not differ significantly between treatment groups for sparrows (19.0 and 6.0 seconds for TC and IPT, respectively) or starlings (88.5 and 77.5 seconds for TC and IPT, respectively). Median times to cessation of pulse were significantly shorter for TC than for IPT in sparrows (0.0 vs 18.5 seconds) and starlings (9.5 vs 151.0 seconds). On necropsy, most (14/17) birds that underwent TC had grossly visible coelomic, pericardial, or perihepatic hemorrhage. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that TC might be an efficient euthanasia method for small birds. Digital pressure directly over the heart during TC obstructed venous return, causing rapid circulatory arrest, with rupture of the atria or vena cava in several birds. The authors propose that cardiac compression is a more accurate description than TC for this procedure.
اظهر المزيد [+] اقل [-]Pigment epithelial function in canine retina
1991
Kommonen, B. | Dawson, W.W. | Parmer, R.
The lateral distribution and temporal changes in the eye standing potential of 15 dogs with normal eyes (as determined by use of an ophthalmoscope and electroretinography) were measured by use of noninvasive methods. The standing potential was converted to an alternating potential by controlled eye movement. The light peak occurred 6 minutes after a stimulus intensity increase of 4 log units. The ratios of the highest measured voltage after the light step divided by the voltage measured immediately before the light step ranged from 1.27 to 2.07 (mean 1.74 +/- SEM, 0.064). The responses typically decayed slowly after the light peak. The potential after the light peak did not return to prelight step values during the observation period. The field potential of the standing potential decreased nonlinearly in temporal direction from the outer canthus.
اظهر المزيد [+] اقل [-]Use of fine-wire electrodes for electromyographic evaluation of the external urethral sphincter during urethral pressure profilometry in male cats
1991
Sackman, J.E. | Sims, M.H.
Evaluation of urethral pressure profilometry (UPP) with simultaneous fine-wire electromyography of the external urethral sphincter (EUS) was conducted in 11 healthy adult male cats sedated with xylazine and ketamine. A 3.5-F urethral catheter with a closed end and two 1-mm sideports was infused with sterile 0.9% NaCl solution at a rate of 2 to 3 ml/min. A fine-wire electromyographic (EMG) electrode was placed percutaneously into or near the external urethral sphincter prior to the onset of the UPP. The maximal urethral pressure achieved and functional profile length were recorded from UPP. Setting both catheter withdrawal rate and paper speed at 5 mm/s enabled the measurement of actual urethral length directly from UPP. Sphincter EMG activity was rated as slight (+), moderate (+ +), or intense (+ + +). All recordings were replicated once during each trial for 8 cats and trials were replicated 5 to 7 days later in 4 cats. Before catheterization, EMG activity of the external urethral sphincter was rated slight (+), whereas intense (+ + +) activity accompanied insertion. The activity evoked by movement of the catheter subsided, but intense EMG activity of the external urethral sphincter was recorded from onset to completion of catheter withdrawal in all cats in both trials. The mean maximal urethral pressure was 93.1 +/- 13.29 cm H2O. The mean function urethral length was 8.1 +/- 0.93 cm. Maximal urethral pressure or function profile length did not differ significantly between recordings within trials or between trials. Simultaneous recording of EMG activity and UPP of the external urethral sphincter was shown to be a simple, noninvasive technique for assessing neuromuscular and anatomic urethral function.
اظهر المزيد [+] اقل [-]Electromyographic evaluation of the external urethral sphincter during cystometry in male cats
1990
Sackman, J.E. | Sims, M.H.
Electromyographic (EMG) evaluation of the external urethral sphincter (EUS) was conducted during cystometry in 11 adult male cats sedated with xylazine and ketamine. A percutaneously placed antepubic catheter was used for bladder infusion and recording intravesicular pressures during cystometrography (CMG). A fine-wire electrode was placed percutaneously into or near the EUS for recording EMG during CMG. The bladder was infused with sterile 0.9% NaCl solution at a rate of 2 to 3 ml/min until a detrusor reflex was initiated. Intravesicular pressures at the onset of infusion, immediately prior to micturition, at the onset of urine flow, and at the maximal voiding pressure were recorded. The time from infusion to micturition, from opening pressure to return to baseline, and from the beginning to the end of the CMG were also recorded. The total volume of 0.9% NaCl solution infused and the residual bladder volume after micturition were also measured. Recordings were replicated once during each trial in all cats, and trials were replicated once approximately 1 week later in 4 cats. Micturition patterns were characterized by slight to moderate EUS EMG activity during vesicular filling, with reduction in activity during emptying. Maximal EMG activity was recorded at the completion of the reflex and was associated with pulsatile expulsion of small amounts of urine. The simultaneous recording of CMG and EUS EMG with fine-wire electrodes was simple and reliable for assessing the neuromuscular integrity and synchrony of detrusor and EUS muscles. There were no significant differences in variables between recordings within trial 1, but there were differences (P less than or equal to 0.05) between trials for pressure at the onset of urine flow and maximal voiding pressure.
اظهر المزيد [+] اقل [-]Myoelectric activity of the ileum, cecum, and right ventral colon in ponies during interdigestive, nonfeeding, and digestive periods
1990
Ross, M.W. | Cullen, K.K. | Rutkowski, J.A.
Myoelectric activity of the ileum, cecum, and right ventral colon (RVC) was studied in 4 mature ponies. Eight Ag-AgCl bipolar recording electrodes were sutured to the seromuscular layer of the ileum (2 electrodes), cecum (4 electrodes), and RVC (2 electrodes). Myoelectric activity was studied beginning 10 days after surgery. Eight, 60-minute recording sessions were performed in each pony during the interdigestive period, which was the period 3 to 7 hours after the morning feeding. On separate days, food was withheld for 24 hours, and 90-minute recordings were obtained during the nonfeeding period. Ponies were then fed a normal ration, and recordings were continued to obtain data for the digestive (feeding) period. All phases of the migrating myoelectric complex were seen at both ileal electrodes during the interdigestive period, including the periods of no spiking activity (phase 1), irregular spiking activity (phase 2), and regular spiking activity (phase 3). Phase 2 occupied 77% of the total recording time, and the mean duration of phases 1, 2, and 3 was 3.4 +/- 0.2, 12.8 +/- 1.2, and 6.7 +/- 0.7 min, respectively. Frequency of ileal slow waves was 11.8 +/- 0.1/min, and spike burst conduction velocity was 4.7 +/- 0.3 cm/s. A complete migrating myoelectric complex was seen in 11 of 32 tracings (34%) and had a mean duration of 24.2 +/- 2.6 min. The ileal migrating action potential complex, most often seen in phase 2, had a frequency of 4.8 +/- 0.5 spike bursts/h and a conduction velocity of 13.6 +/- 0.4 cm/s. The migrating action potential complex was detected directly before retrograde cecal myoelectric activity 73% of the time, indicating possible myoelectric coupling of the ileum and cecum. Motility patterns recognized in the cecum included: pattern I, spike bursts beginning at the apex and conducted to the cranial base; pattern II, spike bursts beginning at the caudal base and conducted to the apex; pattern III, spike bursts beginning at the cranial base and conducted to the apex; and pattern IV, termed the progressive pattern, beginning at the cecal apex, conducted through the cecal base and cecocolic orifice and into the RVC. The progressive pattern was detected at a frequency of 34.2 +/- 1.8 spike bursts/h and was often preceded by (71%), followed by (64%), or preceded and followed by (51%) pattern I or II. This recurring sequence of cecal myoelectric events was termed the cecal myoelectric complex. In the RVC, 2 patterns of myoelectric activity were seen: aborally directed propulsive spike bursts (3.6 +/- 0.6 spike bursts/h) and orally directed retropulsive spike bursts (7.2 +/- 1.2 spike bursts/h), confirming that propulsion and retropulsion exist in the RVC. Nonfeeding caused a significant decrease in the frequency of ileal migrating action potential complex (P = 0.008), cecal pattern III (P = 0.003), and the progressive motility pattern (P = 0.003). Nonfeeding caused a significant decrease (P less than or equal to 0.009) in the appearance of the cecal myoelectric complex. Feeding caused a significant increase (P = 0.003) in the mean frequency of the progressive pattern compared with the nonfeeding period, but this was significantly less than during the interdigestive period (P = 0.003).
اظهر المزيد [+] اقل [-]Evoked potentials induced by transcranial stimulation in dogs
1990
Kraus, K.H. | O'Brien, D. | Pope, E.R. | Kraus, B.H.
Evoked potentials were induced by transcranial stimulation and recovered from the spinal cord, and the radial and sciatic nerves in six dogs. Stimulation was accomplished with an anode placed on the skin over the area of the motor cortex. Evoked potentials were recovered from the thoracic and lumbar spinal cord by electrodes placed transcutaneously in the ligamentum flavum. Evoked potentials were recovered from the radial and sciatic nerves by surgical exposure and electrodes placed in the perineurium. Signals from 100 repetitive stimuli were averaged and analyzed. Waveforms were analyzed for amplitude and latency. Conduction velocities were estimated from wave latencies and distance traveled. The technique allowed recovery of evoked potentials that had similar characteristics among all dogs. Conduction velocities of potentials recovered from the radial and sciatic nerves suggested stimulation of motor pathways; however, the exact origin and pathway of these waves is unknown.
اظهر المزيد [+] اقل [-]Effect of oral administration of gabapentin on the minimum alveolar concentration of isoflurane in dogs النص الكامل
2019
Johnson, Brittney A. | Aarnes, Turni K. | Wanstrath, Audrey W. | Pereira, Carolina H Ricco | Bednarski, Richard M. | Lerche, Phillip | McLoughlin, Mary M.
OBJECTIVE To determine the effect of oral administration of gabapentin (20 mg/kg) on the minimum alveolar concentration (MAC) of isoflurane in dogs. ANIMALS 6 healthy adult dogs (3 males and 3 females with a mean ± SD body weight of 24.8 ± 1.3 kg). PROCEDURES Each dog was anesthetized twice. Dogs were initially assigned to 1 of 2 treatments (gabapentin [20 mg/kg, PO] followed 2 hours later by anesthesia maintained with isoflurane or anesthesia maintained with isoflurane alone). A minimum of 7 days later, dogs received the other treatment. The MAC of isoflurane was determined by use of an iterative bracketing technique with stimulating electrodes placed in the maxillary buccal mucosa. Hemodynamic variables and vital parameters were recorded at the lowest end-tidal isoflurane concentration at which dogs did not respond to the stimulus. Effect of treatment on outcome variables was analyzed by use of a paired t test. RESULTS Mean ± SD MAC of isoflurane was significantly lower when dogs received gabapentin and isoflurane (0.71 ± 0.12%) than when dogs received isoflurane alone (0.91 ± 0.26%). Mean reduction in MAC of isoflurane was 20 ± 14%. Hemodynamic variables did not differ significantly between treatments. Mean time to extubation was significantly less when dogs received gabapentin and isoflurane (6 ± 4 minutes) than when dogs received isoflurane alone (23 ± 15 minutes). CONCLUSIONS AND CLINICAL RELEVANCE Oral administration of gabapentin 2 hours before anesthesia maintained with isoflurane had a MAC-sparing effect with no effect on hemodynamic variables or vital parameters of dogs.
اظهر المزيد [+] اقل [-]Effects of catheter shape, interelectrode spacing, and electrode size on transesophageal atrial pacing in dogs النص الكامل
2016
Sanders, Robert A. | Chapel, Emily H.
OBJECTIVE To determine effects of catheter shape, interelectrode spacing (IS), and electrode size (ES) on pacing threshold (PT), extraneous muscular stimulation (EMS), and zone of capture (ZOC) for dogs undergoing transesophageal atrial pacing (TAP). ANIMALS 10 purpose-bred dogs without cardiac conduction disturbances. PROCEDURES 7 configurations for TAP catheters were tested in each dog to evaluate effects of catheter shape (curved or straight), IS (5, 15, and 25 mm), and ES (2, 4, and 6 mm). Each catheter was passed into the esophagus to a location aboral to the heart and slowly withdrawn until atrial pacing was achieved. Then, catheters were withdrawn in 5-mm increments until pacing could not be achieved. Outcomes measured at each pacing site included PT, degree of EMS, and ZOC. RESULTS There was a significantly lower PT, wider ZOC, and less EMS for the curved catheter than for the straight catheter. An ES of 6 mm induced significantly more EMS than was induced by an ES of 2 or 4 mm. An IS of 5 mm induced significantly less EMS and a significantly narrower ZOC but required a significantly higher PT, compared with results for an ES of 15 or 25 mm. Additionally, there was a significant direct correlation between IS and ZOC. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that a curved catheter with multiple 4-mm electrodes that provides for variable IS would be ideal for TAP in dogs. IMPACT FOR HUMAN MEDICINE TAP catheters currently used in human medicine are straight. The PT in humans may potentially be reduced with curved catheters.
اظهر المزيد [+] اقل [-]Assessment of cord dorsum potentials from caudal nerves in anesthetized clinically normal adult dogs without or during neuromuscular blockade النص الكامل
2013
Campbell, James O. | Olby, Natasha J. | Hash, Jonathan A. | Lascelles, Duncan X.
Objective-To assess the feasibility of measuring cord dorsum potentials (CDPs) in anesthetized clinically normal dogs after caudal nerve stimulation, determine the intervertebral site of maximum amplitude and best waveform of the CDP, and evaluate the effects of neuromuscular blockade. Animals-8 male and 4 female dogs (age, 1 to 5 years). Procedures-Dogs were anesthetized, and CDPs were recorded via needles placed on the dorsal lamina at intervertebral spaces L1-2 through L7-S1. Caudal nerves were stimulated with monopolar electrodes inserted laterally to the level of the caudal vertebrae. Dogs were tested without and during neuromuscular blockade induced with atracurium besylate. The CDP latency and amplitude were determined from the largest amplitude tracings. Results-CDPs were recorded in 11 of 12 dogs without neuromuscular blockade and in all dogs during neuromuscular blockade. The CDP was largest and most isolated at the L4-5 intervertebral space (3 dogs) or the L5-6 intervertebral space (9 dogs); this site corresponded to the segment of insertion of the first caudal nerve. Onset latencies ranged from 2.0 to 4.7 milliseconds, and there was no effect of neuromuscular blockade on latencies. Amplitudes of the CDPs were highly variable for both experimental conditions. Conclusions and Clinical Relevance-CDPs were recorded from all dogs tested in the study; neuromuscular blockade was not critical for successful CDP recording but reduced muscle artifact. This technique may be useful as a tool to assess the caudal nerve roots in dogs suspected of having compressive lumbosacral disease or myelopathies affecting the lumbar intumescence.
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