Doughlas Regalin

Neoformação óssea e osteointegração de biomateriais micro e nanoestruturados em ovinos

A substituicao de parte do tecido osseo se faz necessaria muitas vezes na rotina cirurgica, seja em funcao de fraturas, neoplasias osseas ou enfermidades ortopedicas que acarretem em perda ossea. Neste sentido, tem se buscado biomateriais capazes de promover esta substituicao, evitando o uso de enxertos ou transplantes osseos. O objetivo deste trabalho foi avaliar a capacidade osteoregenerativa de biomateriais em diferentes composicoes, em tibias de ovinos. Foram utilizadas oito ovelhas mesticas texel, com 12 meses de idade e peso medio de 28,5±7,4kg. Apos adequada preparacao anestesica e cirurgica, foram produzidos tres defeitos osseos na diafise das tibias em sua face medial, totalizando seis defeitos de 6mm cada, sendo que quatro foram preenchidos por biomateriais, e dois por fragmentos osseos retirados do proprio animal (autocontrole). Os materiais implantados foram: hidroxiapatita (HA), tricalcio fosfato-β (TCP-β), hidroxiapatita/tricalcio fosfato-b 60/40 (HA/TCP-b 60/40) e o nanocomposito hidroxiapatita/alumina a 5% (HA/Al2O3 a 5%). Os animais foram alocados em dois grupos: Grupo 60 (n=04), em que os animais foram eutanasiados apos 60 dias da colocacao dos implantes e Grupo 90 (n=04), em que a eutanasia ocorreu 90 dias apos a colocacao dos implantes. Foram realizadas radiografias nos periodos pre-operatorio, imediatamente apos o procedimento e aos 30, 60 e 90 dias de pos-operatorio, a fim de excluir qualquer alteracao previa ou complicacao pos-operatoria, capaz de comprometer o estudo. Apos a eutanasia, foram coletadas as tibias para avaliacao macro e microscopica, por meio de microscopia eletronica de varredura (MEV) e microscopia optica. Os resultados encontrados mostraram uma boa capacidade de neoformacao ossea e uma lenta absorcao da HA. O TCP-β foi rapidamente absorvido e apresentou boa capacidade osteoindutiva e osteocondutiva, sendo observada neoformacao ossea no interior dos grânulos deste biomaterial. O composto bifasico HA/TCP-β (60/40) apresentou o melhor resultado a longo prazo, devido ao melhor controle na solubilizacao e liberacao dos ions calcio e fosfatos para o meio biologico durante o processo de neoformacao ossea. O biomaterial nanocomposito HA/Al2O3 a 5% nao apresentou resultados promissores neste estudo, e sugerem-se novas pesquisas a fim de investigar melhor o potencial e aplicabilidade deste novo biomaterial. Conclui-se que a hidroxiapatita, o tricalcio fosfato-β e a associacao HA/TCP-β (60/40) apresentam excelente capacidade de reparacao ossea, podendo ser utilizados como substitutos osseos; a associacao HA/TCP-β (60/40) e o melhor dentre os biomateriais estudados, pois apresenta velocidade de absorcao intermediaria em relacao a HA e ao TCP-β isolados, fornecendo ainda uma sustentacao adequada ao tecido neoformado; o biomaterial HA/Al2O3 5% se mostrou incompativel, provocando reacao de rejeicao por parte do hospedeiro e com insignificante formacao de tecido osseo, sugerindo novas pesquisas acerca deste material.

Evaluation of the clinical and cardiorespiratory effects of propofol microemulsion in dogs

This research aimed to evaluate the clinical and cardiorespiratory effects of a propofol formulation with nanometer droplet diameter in dogs. Six adult healthy female dogs weighing 14.8±1.2kg were used in this study. Each dog received two treatments with a 15-day washout period. A microemulsion (MICRO) or lipid emulsion (EMU) of propofol was administered intravenously (IV) for induction and maintenance of anesthesia. Anesthesia was maintained with a constant rate infusion of propofol (0.4mg kg-1 minute-1). Cardiorespiratory variables were recorded before induction (baseline), immediately after and at 15-minute intervals for 90 minutes after treatment. Arterial blood samples were also taken for blood gas analysis, except at 45 and 75 minutes after induction. The mean arterial pressure decreased significantly during both treatments, while the cardiac index decreased significantly only in MICRO treatment. The time to extubation, sternal recumbency, ambulation and total recovery was similar in both treatments. Opisthotonos was observed in 33% of the animals in each treatment. The propofol microemulsion presented clinical and respiratory parameters similar to those obtained with the lipid emulsion commercially available, but had some significantly different hemodynamic characteristics when used for inducing and maintaining anesthesia. Based only in these results, no advantages are seen in the use of this new microemulsion.

Efeitos cardiovascular e metabólico da reposição volêmica com hidroxietilamido 130/0,4 em felinos domésticos com hipovolemia induzida

The aim of this study was to compare the volemic expansion effects produced by hydroxyethyl starch 130/0.4 (HES 130/0.4) or blood, in female cats with induced hypovolemia. Twelve healthy adult female cats, crossbreed and weighing an average of 2.85±0.28kg were used. They were induced into general anesthesia with isofluorane at 5V%, intubated and connected to a non-rebreathing system. After instrumentation, the animals were maintained under anesthesia with isofluorane at 1.3V% and maintained on pressure cycled mechanic ventilation. Afterwards, hypovolemia was induced by withdrawal of 30ml kg-1 of blood from the femoral artery. After 60 minutes of stabilization of the patient, the treatments were initiated. In the hydroxyethyl starch group (GH, n=06) the animals received hydroxyethyl starch 130/0.4 as volemic expansion at the same volume of blood withdrawed, in the blood group (GS, n=06) the animals received their own withdrawed blood, being considered the control group. The systolic, diastolic and mean arterial pressures and central venous pressure increased after volemic expansion in both groups. An increase of PaCO2 at T15, T30 and T60 in GH was observed. In addition, there was reduction of pH at T30 and T45 and Na+ ions at T90 in GH. The arterial pressure restoration with the use of HES 130/0.4 was similar to the control group; the volemic expansion with HES 130/0,4 produces accentuated increase of CVP; the use of HES 130/0,4 in female cats submitted to hypovolemia did not produce clinically significant alterations in acid-base equilibrium.

Anestesia geral inalatória ou total intravenosa associada a anestesia subaracnóidea, em ovinos

The purpose of this study was to evaluate the efficacy and safety of sheep submitted to inhalation anesthesia with isoflurane or total intravenous anesthesia with propofol, both associated with subarachnoid anesthesia. Fourteen animals were pre-medicated with 0.3mg.kg-1 morphine IM, and 5 minutes later received 20mcg.kg-1 detomidine IV. Then they were allocated into two groups: GISO (n=7), which were induced with 0.5mg.kg-1 of diazepam and 5mg.kg-1 of ketamine IV, and anesthesia maintenance was performed by isoflurane diluted in 100% oxygen; or GPRO (n=7), where animals were induced with 4mg.kg-1 propofol IV and subsequent maintenance anesthesia with its own infusion of 0.3mg.kg.min-1. To perform the bilateral tibial osteotomy, all animals received 0.5mg.kg-1 0.75% ropivacaine combined with 0.1mg.kg-1 morphine by the intrathecal route. There was a 40% reduction in mean heart rate after the sedative protocol in both groups, resulting in a 23% average reduction until the end of the review. Mean arterial pressure showed transient elevation of around 16%, after induction of anesthesia in GISO, but reducing it to the end of the procedure, as well as in GPRO. The average EtISO was 0.57 V% and average infusion rate of propofol was 0.24mg.kg-1.min-1. The total time of surgery, anesthesia and extubation was 66± 9.8, 92±7.0 and 13.8±1.5 minutes in GISO and 56±2.4, 82.9±4.6 and 5.4±1.5 minutes in GPRO. The maintenance of anesthesia with propofol or isoflurane produced similar anesthesia with minimal cardiovascular and blood gas effects, which are well tolerated in healthy sheep.

Calorimetria indireta na monitoração hemodinâmica e metabólica em cães sob diferentes situações hemodinâmicas

Monitoring the hemodynamic state seeks a balance between the supply and demand of oxygen by tissues. The aim of this study was to evaluate the use of indirect calorimetry (IC) compared to thermodilution (TD) in dogs under different hemodynamic states. Nine dogs weighing 19.6±1.3kg were anesthetized with isoflurane at 1.4 V% (Baseline) and subjected to mechanical ventilation (MV), a hypodynamic state (Hypo) with isoflurane at 3.5V% and hyperdynamic state (Hyper) with dobutamine infusion at 5μg/kg/min. We used a Swan-Ganz catheter for measurement of cardiac index (CI) by TD, calculation of oxygen consumption by Ficks method (VO2 Fick ) and to collect central and mixed venous blood. With the IC we obtained oxygen consumption (VO2), CO2 production (VCO2) and end tidal CO2 (EtCO2). For the determination of CI by IC we used the Ficks principle with VO2 values, and arterial and mixed venous blood (Fick mix ) or arterial and central venous blood (Fick vc ); and by the ratio of the values of VCO2 and EtCO2 (Fick CO2 ). We performed the statistical analysis by Dunnet tests, for the difference between the states, and Tukey for differences between methods (P≤0.05). Pearson correlation and Bland-Altman analysis was performed for correlation and agreement analysis. IC provided VO2 values 30 to 40% higher than the VO2 Fick but identified the reduction in VO2 after VM and Hypo,

Epidural administration of ropivacaine or ropivacaine and xylazine in cattle

Protocolos epidurais sao comumente utilizados em bovinos, possibilitando inclusive a realizacao de procedimentos cirurgicos com o animal em posicao quadrupedal, no entanto, problemas como paresia e decubito, alem do tempo de bloqueio/recuperacao sao fatores importantes na escolha do protocolo. O objetivo deste estudo foi avaliar dois protocolos de anestesia epidural em bovinos, quanto ao tempo, qualidade de bloqueio e efeitos clinicos. Foram utilizadas 14 vacas mesticas, com peso medio de 350±170 kg, as quais foram alocadas em dois grupos: ropivacaina (GR, n=7) onde os animais receberam a administracao epidural de ropivacaina (0,1 mg.kg-1) e ropivacaina/xilazina (GRX, n=7) que receberam ropivacaina e xilazina (0,075 e 0,05 mg.kg-1, respectivamente) pela mesma via. Avaliou-se: frequencia cardiaca (FC), frequencia respiratoria ( f ), pressao arterial media (PAM), movimentos ruminais (MR), temperatura retal (TR), tempo de duracao do bloqueio anestesico (TB), qualidade do bloqueio (QB) atraves da resposta a estimulos nociceptivos pelo clampeamento perineal, grau de paresia (GP) e hemogasometria arterial. Os animais foram avaliados por ate 420 minutos apos a administracao. A FC, f, PAM, pH, PaCO2, Na+, Ca++, HCO3 - e Excesso de Base (EB) nao diferiram entre grupos. Foi observada uma leve diminuicao nos movimentos ruminais e aumento da PaO2 e TR no GRX comparado ao GR. A duracao do bloqueio sensitivo foi de 6 e 7 horas para o GR e GRX, respectivamente. A QB foi considerada boa/excelente frente a estimulacao nociceptiva em 66% e 71% dos animais do GR em M360 e do GRX em M420. Os animais do GRX apresentaram sinais de paresia moderada a grave de M15 ate M240. Conclui-se que a ropivacaina associada a xilazina pela via epidural apresenta bloqueio sensitivo mais prolongado do que a ropivacaina isolada, no entanto a associacao com a xilazina promove bloqueio motor, com sinais de paresia, devendo ser utilizada com cautela em bovinos.

Respostas cardiorrespiratória e metabólica do propofol nas formulações em emulsão lipídica ou microemulsão em gatas

The aim of the present study was to evaluate the cardiorespiratory and metabolic effects from lipid emulsion and microemulsion of propofol in cats. Twelve healthy adult cats were included, and divided into two groups: microemulsion group (MICRO, n=6) and lipid emulsion (EMU, n=6), where they received propofol in the respective formulation, in a dose sufficient for intubation. The animals were then intubated and provided with 100% oxygen through a non-rebreathing circuit. Immediately after, the infusion of propofol was initiated (0.3mg kg-1 min-1) and maintained for 90 minutes. The dose required for induction was 9.5±1.3mg kg-1 and 10±1mg kg-1 in MICRO and EMU, respectively. The SAP, MAP, DAP and pH values were lower in all moments in EMU when compared to MICRO; the RR in EMU was lower from T30 to T75 in comparison to MICRO. The paCO2 was greater in the EMU from T15 to T90. The times to extubation, sternal recumbency, ambulation and total recovery were 40.6±30.7, 91±37.5, 134.5±54.5 and 169.1±55.4 minutes in MICRO and 68.8±37.3, 133.3±85.3, 171.3±77.1 and 233.1±60.6 minutes in EMU, respectively. There was an increase of the enzyme alanine aminotransferase from 12 to 72 hours in EMU and in MICRO from 48 to 72 hours. The propofol in microemulsion presents clinical characteristics of induction and maintenance, and metabolic effects similar to the formulation in lipid emulsion. The microemulsion formulation provides a better cardiovascular and respiratory stability for induction and continuous infusion in healthy cats.

Efeitos cardiovascular e metabólico da reposição volêmica com solução salina hipertônica 7,5% associada ou não ao hidroxietilamido 130/0,4 em gatas com hipovolemia induzida

Hypovolemia is characterized by body fluid loss leading to an inadequate circulatory flow and consequently tissue injury. The aim of this study was to compare the volume expansion using hypertonic saline solution (NaCl 7.5%) alone or in combination with hydroxyethylstarch 130/0.4 (HES 130/0.4) in cats under general anesthesia with isoflurane and exposed to experimental hypovolemia. Twelve adult mixed breed cats, average weight of 3.07±0.56kg were used in this study. The queens were anesthetized using isoflurane and after surgical prepare, anesthesia were maintained with 1 MAC of isoflurane and the animals were mechanically ventilated. After waiting for anesthesia stabilization, baseline cardiovascular and hemogasometric parameters were recorded. Hypovolemia was induced by withdrawing 30mL kg-1 of blood from the femoral artery, after an hour, data were reassessed, and then, the animals were allocated into two groups: HSG (hypertonic saline group, n=6), which received 4mL kg-1 of 7.5% NaCl, and HSCG (hypertonic saline, associated to HES 130/0,4 group n=6) which received 4mL kg-1 of 7.5% NaCl associated to 30ml kg-1 of HES 130/0.4. After the treatments, cardiovascular and hemogasometric parameters were assessed for 120 minutes. Systolic blood pressure (SAP), diastolic blood pressure (DAP), mean arterial pressure (MAP) were significantly higher after volemic expansion on HSG at T0. From T45 to T120, SAP, DAP and MAP were significantly higher in HSCG when compared to HSG. Central venous pressure was higher in HSCG up to T60. There were no significant differences between groups on heart rate, respiratory rate, Na+, K+, base excess, bicarbonate, hemoglobin saturation, glucose, PaCO2, PaO2 and pH. The administration of 7.5% NaCl, promoted a faster increase in MAP, SAP and DAP in cats with induced hypovolemia and these effects were maintained for 30 minutes while the administration of HES 130/0.4 in combination with 7.5% NaCl promoted a delayed reestablishment (30 minutes after treatment) of MAP, SAP and DAP in cats with induced hypovolemia, but lasting up to T120. The combination of HES 130/0.4 and NaCl 7.5% promoted a significant increase on CVP for up to 60 minutes after the treatment.

Avaliação dos parâmetros cardiorrespiratórios, hemogasométricos e da concentração plasmática de cortisol em bovinos submetidos à imobilização eletromagnética

The ways of immobilization generally used in cattle provide excessive manipulation and stress for the animal. The pain is an emotional experience and unpleasant sensation in combination with tissue damage. The new method of physical restraint for cattle uses low intensity electromagnetic waves, promising immobilization without stress or painful stimulation for the animals. The aim of this study is to evaluate of cardiorespiratory effects and plasmatic cortisol concentration of cattle submitted to electromagnetic immobilization. Six healthy cows with average weight of 300.3 ± 85.76 kg (mean ± SD) were assigned to two treatments in a randomized design with a 15-day interval between experiments GC (control group) and GI (immobilization group). Data are presented as mean + SD. The statistical analyses used the t-Test between groups, and ANOVA random block design between times into same group. All statistical analyses were performed using P<0.05 as a significant level. Evaluation moments: M1 (basal); M1: after withdrawal probe, M2 and M3 (30 and 60 minutes after M1 respectively). There was a significant increase of FC and f in M1, PAM in the moments (M1, M2, M3) and in the levels of plasmatic cortisol concentration in M1 e M2 in the immobilization group when to compared with the control group. It could be concluded that this electromagnetic immobilization is a method of physic restraint only, offers no anesthetic support and favors comfort and animal welfare.