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This thesis discusses diverse electrochemical strategies for the determination of the concentration of the gases hydrogen sulfide, ammonia and halothane. The chemical tagging of sulfide by a variety of structurally diverse substituted benzoquinone species was studied over a wide range of pH (2<pH<10). Each derivative was found to respond to increasing concentration of sulfide (typically over a range 10-200 μM). The electrochemically initiated reaction of N,N-diethyl-pphenylenediamine (DEPD) with sulfide in N,N-dimethylformamide (DMF) was next examined with quantitative detection of sulfide (linear range= 28-3290 μM, LoD= 22 μM) achieved by analysis of the increase in the second oxidation wave. This is consistent with the sulfide attacking the doubly oxidised species in a 1,4-Michael addition. The direct oxidation of sulfide at a nickel hydroxide film on a nickel electrode in alkaline solution has provided the basis for the design of a simple and inexpensive sensor for monitoring H₂S in the range 20-200 μM. More sensitive (LoD= 1 (μM) amperometric detection of sulfide was obtained at modified nickel electrodes in acidic media in which sulfide was stripped from the nickel oxide layer. This approach was exploited further by using nickel modified screen printed carbon (Ni-SPC) electrodes as economical and disposable sensors for sulfide. Next, two different strategies for determining gaseous ammonia in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide, [EMIM][N(Tf)₂], and in DMF are described. The first approach exploits the effect of ammonia as a proton acceptor species on the anodic oxidation of hydroquinone, resulting in a linear detection range from 10 to 95 ppm ammonia (LoD= 4.2 ppm). The second approach is based on the direct oxidation of ammonia in either DMF or [EMIM][N(Tf)₂]. The possibility of photochemically induced electrocatalytic processes within microdroplets containing p-chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone, TCBQ) was examined as a means of detecting the anaesthetic gas halothane.</p> Finally, two of the more promising routes for sulfide detection were studied at elevated temperatures (up to 70 °C) with a view to developing H₂S sensors capable of meeting the demands of oilfield applications.

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Made available in DSpace on 2014-06-11T19:32:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-02Bitstream added on 2014-06-13T18:44:21Z : No. of bitstreams: 1 jaramillocardenas_j_dr_botfmvz.pdf: 242577 bytes, checksum: 5dcc866f1ed70acb337558dd3e761c21 (MD5) / Universidade Estadual Paulista (UNESP) / A alta mortalidade relacionada a anestesia na espécie eqüina em relação à outras espécies, se deve principalmente à depressão cardiovascular. A taquicardia ventricular (TV) é uma das possíveis arritmias observadas durante a anestesia, classicamente tratada com lidocaina. Objetivou-se avaliar os efeitos cardiorrespiratórios da TV induzida por dopamina, na anestesia por halotano em eqüinos, comparando o efeito da lidocaina e acupuntura para o tratamento deste. Seis eqüinos divididos em três grupos (GC: grupo controle; GA: grupo tratado com acupuntura e GL: grupo tratado com lidocaina), foram estudados para comparar o efeito da lidocaina como método convencional, e da acupuntura nos pontos bilaterais associados: pericárdio 6 (Pc 6 - Neiguan) e Coração 7 (C 7 - Shenmen), na TV induzida pela dose arritmogênica da dopamina (DAD). Os eqüinos foram anestesiados três vezes cada um com xilazina, éter gliceril guaiacol, tiopental e halotano com intervalo de uma semana entre cada anestesia. Foram avaliados os parâmetros cardiovasculares (freqüência cardíaca, pressão arterial e eletrocardiografia), respiratórios (freqüência respiratória, capnografía, saturação de hemoglobina e hemogasometría) e escore de recuperação. A DAD foi determinada a partir da infusão de 70 æg/kg/min IV durante 10 minutos sem interrupção, preenchendo o critério determinado como arritmogênico, pela presença de 4 ou mais complexos ventriculares prematuros seguidos, com duração de pelo menos quinze segundos ou TV sustentada. O tempo médio de aparecimento da DAD ou da TV foi de 6,05 0,45 minutos nos animais não tratados e a TV se reverteu espontaneamente aos 2,7 0,2 minutos. O grupo tratado com acupuntura reverteu a TV em um tempo médio de 1,8 0,2 (P<0,05) em comparação do grupo tratado com lidocaina 1,3 0,2 (P<0,01), ambos se mostrando eficientes no tratamento da TV de eqüinos anestesiados com halotano. / The high mortality related to anesthesia in the equine species compared to other species is mainly due to cardiovascular depression. Ventricular tachycardia (VT) is one of the possible arrhythmias observed during the anesthesia classically treated with lidocaine. The purpose of this study was to evaluate the cardio respiratory effects of VT induced by dopamine in horses anesthetized with halothane, comparing the effect of lidocaine and acupuncture for its treatment. Six horses were allocated to three treatments (CG: control group, AG: acupuncture treated group and LG: lidocaine treated group) and were evaluate to compare the effects of lidocaine as a conventional treatment and the acupuncture in the associated bilateral points: pericardium 6 (Pc 6- Neiguan) and heart 7 (H7 - Shenmen) in VT induced by the arrhythmogenic dose of dopamine (ADD). The horses were anesthetized three times each one using xylazine, guaifenesin, thiopental and halothane with one week interval between each anesthesia. Cardiovascular (heart rate, arterial pressure and ECG) and respiratory (respiratory rate, capnometry, hemoglobin saturation and blood gas analysis) parameters and recovery score were evaluated. The ADD was determined by the infusion of 70 mg/Kg/min during 10 minutes without interruption fulfilling the arrhythmogenic criteria by the presence of 4 or more ectopic ventricular contractions during at least 15 seconds or sustained ventricular tachycardia. The mean time for the occurrence of VT or ADD was 6,05 l 0,45 minutes for control animals and the VT reverted spontaneously at 2,7 l 0,2 minutes. The group treated with acupuncture reverted the VT in a mean time of 1,8 l 0,2 (P<0,05) compared to the group treated with lidocaine 1,3l0,2 (P<0,01), both of them showing to be efficacious for the treatment of VT on horses anesthetized with halothane.

Two trials (n = 160) were conducted to evaluate the effects of the halothane gene, chromium picolinate supplementation, and sex on growth performance, carcass characteristics, and meat quality in pigs. Halothane negative (NN) and halothane carrier (Nn) pigs (barrows, gilts) were supplemented with either 0 or 200 ppb chromium picolinate from 28.7 to 107.3 kg. There were no differences between genotypes for ADG or G/F. Chromium had no significant effect on any growth, carcass, or muscle quality characteristics, although chromium-fed pigs were slightly fatter. Barrows gained faster (P < .001) and consumed more feed (P < .001) than gilts, yielding heavier (P < .001) carcasses, and heavier (P < .05) wholesale cuts. Gilts had less backfat (P < .001) and larger (P < .01) LMA, and tended to gain more efficiently than barrows. Carrier pigs had lower pH values, higher CIE L* values, higher drip loss, and lower protein solubility (P < .05), all indicators of decreased quality. Chromium supplementation resulted in pork with higher (P<.05) CIE a*, CIE b*, and Chroma C values. Halothane carrier barrows and all gilts that were not fed chromium had lower lipid muscle content than NN barrows (P < .05). Gilts had higher CIE L* and a* values (P < .001), less lipid, and higher moisture percentage (P < .02) than barrows. Chromium picolinate did not negatively affect pork muscle quality. / Master of Science

Anesthesia, a state of being absent of sensation and consciousness, has been recognized since antiquity. Even today anesthesia is still best characterized by the lack of consciousness and sensations. Since anesthetic potency is correlated with lipid solubility, the site of action of general anesthetics has been thought to be hydrophobic in nature and to involve excitable membranes critical for interneuronal communications. Thus, general anesthetics may interact directly with functionally-relevant membrane proteins (via hydrophobic pockets) or indirectly, with the lipids surrounding these proteins. To better understand the details of general anesthetic action, I examined how halothane interacts with a functional synaptic protein, the acetylcholine receptor channel embedded in the membranes of cultured Xenopus myocytes. Next, I examined how changing the lipid composition, of these membranes, affected this interaction. Using the extracellular patch-clamp technique, I found that halothane, at clinically-relevant concentrations, shortened the burst duration of single receptor channels without affecting their conductance. Moreover, the halothane-induced reduction of burst durations was significantly attenuated after pretreatment with cholesterol-rich lipsomes which increased significantly the cholesterol content of these cells. These findings provide the first direct support for the role of membrane lipids in the mechanism of GA action. In particular, I demonstrated that increases in membrane cholesterol antagonize the anesthetic action of halothane. Although direct action of cholesterol on synaptic proteins cannot be ruled out, my data strongly suggest that membrane lipids are involved at a critical, but as yet undefined, site with which GAs interact. The exact manner by which increases in membrane cholesterol antagonize GA action remains to be eludicated.

No description available.

A clinical trial was undertaken using three different inhalant anaesthetic agents and one intravenous anaesthetic agent in dogs undergoing routine desexing surgery. Healthy adult dogs undergoing either ovariohysterectomy or castration were assessed as to their demeanour, with the more excitable dogs being placed in groups receiving premedication with acepromazine and morphine. All dogs were then randomly assigned an anaesthetic agent for induction of general anaesthesia. The agents were the inhalants halothane, isoflurane and sevoflurane, and the intravenous agent propofol. Inhalant inductions were undertaken using a tight fitting mask attached to a standard anaesthetic machine with a rebreathing circuit, with the maximum dose of inhalant available from a standard vaporiser. Propofol inductions were undertaken via intravenous catheter. Dogs induced with propofol were randomly assigned one of the three inhalant agents for maintenance. Those induced by inhalant agent were maintained using the same agent. The surgical procedure was undertaken in standard fashion, as was recovery from anaesthesia. All dogs received the non-steroidal anti-inflammatory agent meloxicam. Data collection was divided into three stages: induction, maintenance, and recovery from anaesthesia. Variables measured at induction of anaesthesia were time to intubation, number of intubation attempts, tolerance of mask, quality of induction and quality of transfer to the maintenance stage. Standard variables for monitoring of anaesthesia were recorded throughout the maintenance of anaesthesia. Variables measured at recovery were time to righting, time to standing and quality of recovery. The mean time to intubation when using the newer inhalant sevoflurane (196.2 � 14.8sec, mean � SE) was not significantly different to that for halothane (221.4 � 14.0sec) or isoflurane (172.4 � 15.0sec). Time to intubation with isoflurane was significantly faster than with halothane. Mean time to intubation with propofol (85.4 � 7.7sec) was significantly faster than that for any of the three inhalants. Choice of inhalant had no effect on quality of induction. The use of premedication significantly improved the quality of induction. The use of propofol for induction likewise significantly improved the quality of induction. Standard cardiorespiratory variables measured during the maintenance phase of anaesthesia remained within normal clinical ranges for all three inhalants, and were therefore not further analysed. Choice of inhalant agent had no significant effect on the time to righting or standing in recovery. The use of propofol for induction had no effect on these variables. Animals placed in groups receiving premedication had significantly longer times to righting and standing. The oesophageal temperature at the end of the procedure had a significant effect on times to righting and standing, with lower temperatures contributing to slower recoveries. Independent of procedure time, male dogs had shorter times to righting than female dogs.

A clinical trial was undertaken using three different inhalant anaesthetic agents and one intravenous anaesthetic agent in dogs undergoing routine desexing surgery. Healthy adult dogs undergoing either ovariohysterectomy or castration were assessed as to their demeanour, with the more excitable dogs being placed in groups receiving premedication with acepromazine and morphine. All dogs were then randomly assigned an anaesthetic agent for induction of general anaesthesia. The agents were the inhalants halothane, isoflurane and sevoflurane, and the intravenous agent propofol. Inhalant inductions were undertaken using a tight fitting mask attached to a standard anaesthetic machine with a rebreathing circuit, with the maximum dose of inhalant available from a standard vaporiser. Propofol inductions were undertaken via intravenous catheter. Dogs induced with propofol were randomly assigned one of the three inhalant agents for maintenance. Those induced by inhalant agent were maintained using the same agent. The surgical procedure was undertaken in standard fashion, as was recovery from anaesthesia. All dogs received the non-steroidal anti-inflammatory agent meloxicam. Data collection was divided into three stages: induction, maintenance, and recovery from anaesthesia. Variables measured at induction of anaesthesia were time to intubation, number of intubation attempts, tolerance of mask, quality of induction and quality of transfer to the maintenance stage. Standard variables for monitoring of anaesthesia were recorded throughout the maintenance of anaesthesia. Variables measured at recovery were time to righting, time to standing and quality of recovery. The mean time to intubation when using the newer inhalant sevoflurane (196.2 � 14.8sec, mean � SE) was not significantly different to that for halothane (221.4 � 14.0sec) or isoflurane (172.4 � 15.0sec). Time to intubation with isoflurane was significantly faster than with halothane. Mean time to intubation with propofol (85.4 � 7.7sec) was significantly faster than that for any of the three inhalants. Choice of inhalant had no effect on quality of induction. The use of premedication significantly improved the quality of induction. The use of propofol for induction likewise significantly improved the quality of induction. Standard cardiorespiratory variables measured during the maintenance phase of anaesthesia remained within normal clinical ranges for all three inhalants, and were therefore not further analysed. Choice of inhalant agent had no significant effect on the time to righting or standing in recovery. The use of propofol for induction had no effect on these variables. Animals placed in groups receiving premedication had significantly longer times to righting and standing. The oesophageal temperature at the end of the procedure had a significant effect on times to righting and standing, with lower temperatures contributing to slower recoveries. Independent of procedure time, male dogs had shorter times to righting than female dogs.

Orientador: Stelio Pacca Loureiro Luna / Banca: Denise Saretta Schwartz / Banca: Denise Fantoni / Banca: Renata Navarro Cassu / Banca: Francisco Teixeira Neto / Resumo: A alta mortalidade relacionada a anestesia na espécie eqüina em relação à outras espécies, se deve principalmente à depressão cardiovascular. A taquicardia ventricular (TV) é uma das possíveis arritmias observadas durante a anestesia, classicamente tratada com lidocaina. Objetivou-se avaliar os efeitos cardiorrespiratórios da TV induzida por dopamina, na anestesia por halotano em eqüinos, comparando o efeito da lidocaina e acupuntura para o tratamento deste. Seis eqüinos divididos em três grupos (GC: grupo controle; GA: grupo tratado com acupuntura e GL: grupo tratado com lidocaina), foram estudados para comparar o efeito da lidocaina como método convencional, e da acupuntura nos pontos bilaterais associados: pericárdio 6 (Pc 6 - Neiguan) e Coração 7 (C 7 - Shenmen), na TV induzida pela dose arritmogênica da dopamina (DAD). Os eqüinos foram anestesiados três vezes cada um com xilazina, éter gliceril guaiacol, tiopental e halotano com intervalo de uma semana entre cada anestesia. Foram avaliados os parâmetros cardiovasculares (freqüência cardíaca, pressão arterial e eletrocardiografia), respiratórios (freqüência respiratória, capnografía, saturação de hemoglobina e hemogasometría) e escore de recuperação. A DAD foi determinada a partir da infusão de 70 æg/kg/min IV durante 10 minutos sem interrupção, preenchendo o critério determinado como arritmogênico, pela presença de 4 ou mais complexos ventriculares prematuros seguidos, com duração de pelo menos quinze segundos ou TV sustentada. O tempo médio de aparecimento da DAD ou da TV foi de 6,05 0,45 minutos nos animais não tratados e a TV se reverteu espontaneamente aos 2,7 0,2 minutos. O grupo tratado com acupuntura reverteu a TV em um tempo médio de 1,8 0,2 (P<0,05) em comparação do grupo tratado com lidocaina 1,3 0,2 (P<0,01), ambos se mostrando eficientes no tratamento da TV de eqüinos anestesiados com halotano. / Abstract: The high mortality related to anesthesia in the equine species compared to other species is mainly due to cardiovascular depression. Ventricular tachycardia (VT) is one of the possible arrhythmias observed during the anesthesia classically treated with lidocaine. The purpose of this study was to evaluate the cardio respiratory effects of VT induced by dopamine in horses anesthetized with halothane, comparing the effect of lidocaine and acupuncture for its treatment. Six horses were allocated to three treatments (CG: control group, AG: acupuncture treated group and LG: lidocaine treated group) and were evaluate to compare the effects of lidocaine as a conventional treatment and the acupuncture in the associated bilateral points: pericardium 6 (Pc 6- Neiguan) and heart 7 (H7 - Shenmen) in VT induced by the arrhythmogenic dose of dopamine (ADD). The horses were anesthetized three times each one using xylazine, guaifenesin, thiopental and halothane with one week interval between each anesthesia. Cardiovascular (heart rate, arterial pressure and ECG) and respiratory (respiratory rate, capnometry, hemoglobin saturation and blood gas analysis) parameters and recovery score were evaluated. The ADD was determined by the infusion of 70 mg/Kg/min during 10 minutes without interruption fulfilling the arrhythmogenic criteria by the presence of 4 or more ectopic ventricular contractions during at least 15 seconds or sustained ventricular tachycardia. The mean time for the occurrence of VT or ADD was 6,05 l 0,45 minutes for control animals and the VT reverted spontaneously at 2,7 l 0,2 minutes. The group treated with acupuncture reverted the VT in a mean time of 1,8 l 0,2 (P<0,05) compared to the group treated with lidocaine 1,3l0,2 (P<0,01), both of them showing to be efficacious for the treatment of VT on horses anesthetized with halothane. / Doutor