Ketamine Xylazine Research Articles

Valores hematológicos del mono choro común (Lagothrix lagotricha) mantenido en cautiverio en la ciudad de Lima (Perú)

La disminución de las poblaciones del mono choro común (Lagothrix lagotricha) ha conllevado a categorizarlo como especie amenazada, además, muchos ejemplares se mantienen en cautiverio debido al tráfico ilegal. La hematología es una herramienta muy útil para evaluar el bienestar y diagnóstico de condiciones patológicas, siendo necesario contar con parámetros referenciales para todas las especies de primates mantenidas en cautiverio. El objetivo del presente estudio fue determinar los valores hematológicos de ejemplares de mono choro común (L. lagotricha) bajo cautiverio en los zoológicos de la ciudad de Lima, (Perú). Para ello, el estudio contó con una población total de 28 individuos distribuidos en siete zoológicos, 16 hembras y 12 machos de cuatro grupos etarios diferentes. Se realizó la captura y contención físico-química de los primates utilizando mallas y un protocolo anestésico combinando clorhidrato de ketamina y xilazina. Las muestras de sangre se obtuvieron por punción de la vena femoral, se colectaron en tubos estériles con anticoagulante EDTA y se mantuvieron en refrigeración hasta su análisis. Se obtuvieron los siguientes resultados: eritrocitos 8,76 x 106/μl (± 2,91); hematocrito 36,46% (± 3,38); hemoglobina 12,32 g/dl (± 1,89); VCM 60,61 fl (± 7,85); HCM 20,37 pg (± 3.07); CMCH 33,85 g/dl (± 4,61); leucocitos 6,12 x 103/µl (± 1,05); abastonados 0,05 x 103/µl (± 0,11); segmentados 5,54 x 103/µl (± 2,23); linfocitos 2,62 x 103/µl (± 1,60); monocitos 0,07 x 103/µl (± 0,02); eosinófilos 0,42 x 103/µl (± 0,23); basófilos 0,13 x 103/µl (± 0,14) y plaquetas 314,39 x 103/µl (± 78,09). Se encontró diferencia estadística significativa para el valor de monocitos en relación al sexo.

Cardiopulmonary effects and recovery characteristics of horses anesthetized with xylazine–ketamine with midazolam or propofol

ObjectiveTo evaluate cardiopulmonary and recovery characteristics of horses administered total intravenous anesthesia (TIVA) with xylazine and ketamine combined with midazolam or propofol. Study designRandomized crossover study. AnimalsA group of eight adult horses, aged 7–22 years, weighing 493–740 kg. MethodsHorses were administered xylazine (1 mg kg−1) intravenously (IV), and anesthesia was induced with ketamine (2.2 mg kg−1) IV. Anesthesia was maintained for 45 minutes via IV infusion of xylazine (0.016 mg kg−1 minute−1) and ketamine (0.03 mg kg−1 minute−1) combined with midazolam at 0.002 mg kg−1 minute−1 (MKX), propofol at 0.05 mg kg−1 minute−1 (PKXlow) or propofol at 0.1 mg kg−1 minute−1 (PKXhigh). Additional ketamine was administered if a horse moved spontaneously. Cardiopulmonary variables, blood gases, lactate concentration, packed cell volume and total solids were recorded before sedation (baseline), at 10, 20, 30 and 45 minutes during TIVA and 10 minutes after standing. Recovery variables and quantitative recovery scores were compared. Significance was set at p < 0.05. ResultsAdditional ketamine was required for 50% of MKX horses. Systolic arterial pressure was elevated in MKX at 20 minutes compared with baseline (p = 0.043), at 10 and 20 minutes compared with PKXhigh (p = 0.007, p = 0.024) and at 20 and 30 minutes compared with PKXlow (p = 0.009, p = 0.02). MKX horses (5/8) were hypertensive compared with PKXlow (1/8; p = 0.017). All horses became hypoxemic (PaO2 ≤80 mmHg; 10.7 kPa) during TIVA. Recovery variables did not differ among treatments. Conclusions and clinical relevancePKXlow and PKXhigh had similar cardiopulmonary and recovery performance compared with MKX. PKX combinations provided superior quality of anesthesia to that of MKX. A combination of propofol, ketamine and xylazine administered as TIVA can be used in horses to provide anesthesia for short procedures. Supplemental oxygen is recommended.

Micro-fragmented fat injection reduces sepsis-induced acute inflammatory response in a mouse model

BackgroundSevere sepsis has a high mortality rate. There is increasing evidence that human mesenchymal stem cells possess immunomodulatory properties in sepsis, particularly those from adipose tissue. We hypothesised that micro-fragmented human fat, obtained with minimal alteration of the stromal vascular niche, attenuates the inflammatory response and improves outcome in a murine model of sepsis. MethodsMicro-fragmented fat, lipoaspirate, or saline was administered intraperitoneally 2 h after caecal ligation and puncture (CLP) in C57Bl/6RJ ketamine–xylazine anaesthetised mice. The primary endpoint was the inflammatory score. Secondary endpoints included survival, physiological, histological, and biological parameters. ResultsIn CLP mice, micro-fragmented fat administration significantly decreased the median (range) inflammatory score compared with saline [17 (14–20) vs 9 (8–12), P=0.006]. Secondary endpoints were also significantly improved in micro-fragmented fat-treated compared with saline-treated CLP mice. Improvement in inflammatory score and in survival was suppressed when micro-fragmented fat was co-administered with liposomes loaded with clodronate (macrophage toxin) or NS-398 (cyclo-oxygenase 2 inhibitor), but not with SC-560 (cyclo-oxygenase 1 inhibitor). ConclusionsIn a murine model of severe sepsis, micro-fragmented fat improved early inflammatory status and outcome, at least in part, by a cyclo-oxygenase-2-mediated mechanism. The potential therapeutic value of micro-fragmented fat in severe sepsis warrants further investigation.

THE USE OF KETAMINE-XYLAZINE OR BUTORPHANOL-AZAPERONE-MEDETOMIDINE TO IMMOBILIZE AMERICAN BLACK BEARS ( URSUS AMERICANUS).

Wildlife anesthetic protocols must offer rapid inductions and recoveries, be physiologically safe, and be minimally regulated. With this in mind, we evaluated differences in induction and recovery times and physiological parameters in 33 American black bears ( Ursus americanus) anesthetized with ketamine-xylazine (KX) or immobilized with a commercial drug combination of butorphanol, azaperone, and medetomidine (BAM). Dose was based on mass estimated from field observations. Bears were housed at Appalachian Bear Rescue, Townsend, Tennessee, US, or free-ranging within the Great Smoky Mountains National Park (Tennessee and North Carolina, US) and chemically immobilized for management purposes. From 11 April to 29 June 2016, we immobilized bears with injection via pole syringe or disposable dart projected from an air-powered dart rifle. Once immobilized, we measured each bear's temperature, respiration (breaths/min), heart rate (beats/min), hemoglobin oxygen saturation (via pulse oximetry), arterial blood gases, and mass (kg). We found no differences in the induction parameters, partial pressures of CO2, and rectal temperatures. The BAM-treated bears had lower heart and respiratory rates that led to lower hemoglobin oxygen saturation levels (from blood gas analysis, SaO2). The SaO2 after treatment with BAM (91.1±0.8%) was lower than with KX (93.4±0.9%). After handling, we reversed KX-treated bears with a x̄=0.2±0.02 mg/kg yohimbine and BAM-treated bears with x̄=1.5±0.1 mg/kg atipamezole and 0.8±0.1 mg/kg naltrexone. We found no differences in the recovery times to increased respiration and to the bear assuming a head-up position. The BAM-treated bears stood and recovered quicker than did KX-treated animals. Based on our observations, BAM appears to offer safe, predictable immobilizations with fewer drawbacks and faster recovery times than KX-treated bears.

Evaluation of a pinhole castration technique in ponies: Comparing single with double ligation (using silk or catgut) of the spermatic cord

SummaryThe objective of the study was to evaluate a pinhole castration technique in male ponies. Adult ponies (n = 12) were randomly allotted to one of the two equal groups. Both of the groups were anaesthetised with xylazine–ketamine–diazepam and had single (SLS, SLC) ligation of the spermatic cord on one side and double (DLS, DLC) ligation on the other side using silk (Group T1) and catgut (Group T2). Single ligation whether using silk or catgut (SLS and SLC) was completed in 3.50 ± 0.34 min. DLS took 6.66 ± 0.49 min and DLC 7.16 ± 0.47 min. Scrotal oedema was noticed in all of the ponies from Day 1 to Day 15. The scrotal circumference and testicular volume in animals of both of the groups showed a significant (P&lt;0.05) increase from Day 1 to Day 4. Orchiectomy to recover testicular remnants was performed in all of the animals on Day 41. Straw‐coloured fluid accumulation was noticed in seven testicular remnants (4 T1 and 3 T2). One testicle from Group DLS showed suppuration. Multiple gross and histological abnormalities were detected in all double ligated testes. The changes were more severe in the DLS than the DLC group and their epididymis (n = 3) also showed necrosis, fibroplasia and an obstructed lumen. Severe adhesions had developed in three and one testicle only from the SLS and SLC groups respectively. The remaining testes and epididymis in both of these groups showed only mild‐to‐moderate adhesions. From this study, it was concluded that castration may not be achieved by percutaneous single ligation of the spermatic cord in ponies. Although double ligation induces marked gross and histopathological changes, assessments of the testosterone levels and sperm analysis are required before recommending this procedure. Use of silk for ligation of the spermatic cord is advantageous over catgut but maintenance of strict asepsis is mandatory.

Evaluation of the anesthetic effects of xylazine-ketamine, xylazine-tiletamine-zolazepam and tiletamine-zolazepam using clinical and laboratory parameters in rabbits

The aim of this study was to evaluate the anesthetic effects of xylazine-ketamine (XK), xylazine-tiletamine-zolazepam (XTZ) and tiletamine-zolazepam (TZ) using hematological and biochemical parameters in rabbits. A total of 18 rabbits were divided into three equal treatment groups (n = 6). The rabbits in the XK, XTZ, and TZ groups were administered xylazine (5 mg/kg) and ketamine (50 mg/kg), xylazine (5 mg/kg) and TZ (15 mg/kg), and TZ (15 mg/kg), respectively, via the intramuscular route. Following the injection, their reflexes were tested every 5 minutes. Heart rate, respiratory rate, and body temperature were determined before the injection (0 min) and at 5, 15, 30, 45, 60, 75, 90, and 120 min after injecting the anesthetic combinations. Furthermore, hematological and biochemical (alanine transaminase [ALT], aspartate transaminase [AST], alkaline phosphatase [ALP], bilirubin, blood urea nitrogen [BUN], and urea) analyses were also performed before, during, and after anesthesia administration. The duration of anesthesia and loss of reflexes were significantly longer in the XTZ group than in the other groups. However, in the TZ group, reflexes were remained. Respiratory rate and body temperature decreased in all the groups. Moreover, heart rate reduced only in the XK and XTZ groups, and the hematological parameters of all groups were comparable. Serum AST and ALP levels increased in the XTZ group compared to that in the XK and TZ groups, respectively. However, these increases were within the reference limits. The post-anesthesia serum BUN and urea levels significantly increased in the XTZ group (p &amp;lt; 0.05) compared to that in the other groups. Thus, although the XTZ combination provided satisfactory anesthetic effect in rabbits, it may be nephrotoxic. Therefore, its use for anesthesia induction in invasive renal procedures and experimental nephrotoxicity studies is not advisable..

Comparison between the anaesthetic effects of xylazine–ketamine and diazepam–ketamine: physiological and blood parameters in young hamadryas baboons (Papio hamadryas)

The objective of this study was to evaluate the anaesthetic effects on young hamadryas baboons (Papio hamadryas) of xylazine-ketamine (XK) compared to diazepam-ketamine (DK). Six healthy young male hamadryas baboons were first premedicated with xylazine HCl (0.5 mg/kg, IM) and anaesthetised 20 min later with ketamine (10 mg/kg, IM). After a 10-day washout period, the hamadryas baboons were premedicated with diazepam (1 mg/kg, IM) and anaesthetised 20 min later with ketamine (10 mg/kg, IM). The onset, duration, and the depth of anaesthesia were determined by recording palpebral, corneal, and jaw reflexes. The results showed a significant decrease in heart rate and rectal temperature after XK injection, while a significant reduction in respiratory rate was seen when using the DK protocol. A highly significant increase in the levels of glucose was observed with the XK regimen. Blood pressure decreased when using both anaesthetic regimens, but this reduction did not reach significant levels. The quality of recovery was better when using XK compared to DK. In conclusion, major complications including bradycardia, hypothermia, and hyperglycaemia should be considered with a combination of XK. However, no complications other than bradypnea and hypercapnia should be expected when immobilising young hamadryas baboons with DK. No significant difference was observed in CBC, electrolytes, or lactate level between the anaesthesia protocols.

PHYSICAL EXERCISE AFTER IMMOBILIZATION OF SKELETAL MUSCLE OF ADULT AND AGED RATS

ABSTRACT Introduction: Immobilization is a treatment technique often used to reduce pain and prevent worsening of the injury. However, it promotes harmful effects on musculoskeletal tissue, resulting in a marked loss of muscle function, which may be aggravated in the elderly. Physical exercise is an important intervention to mitigate these harmful effects. Objective: To analyze possible morphometric changes in the gastrocnemius muscle of rats after immobilization and remobilization with physical exercise. Methods: Fifty-six rats were divided into adult (A) and aged (E) groups and subdivided into adult and aged control (AC and EC), immobilized (AI and EI), free remobilized (AIF and EIF), and remobilized through physical exercise (AIE and EIE). The hind limbs were immobilized with the gastrocnemius muscle in a shortened position for a period of seven days, except for the control group. The exercise protocol consisted of five swimming sessions, once per day (25 minutes/session). The animals were euthanized by administration of an overdose of ketamine hydrochloride plus xylazine hydrochloride, followed by sample collection and preparation of hematoxylin and eosin slides. Measurements of the smallest diameter of 120 muscle fibers of each animal were taken with software NIS-Elements D3.0 - SP7 - Nikon® instruments Inc., NY, USA. Results: There was a significant reduction in the mean fiber diameter in the AI (38.43 µm ± 4.20; p=0.01) and AIF (36.97 µm ± 3.41; p&lt;0.01) groups compared to AC (45.39 µm ± 3.41) and in the EI (42.26 µm ± 4.39; p&lt;0.01), EIF (36.00 µm ± 4.15; p&lt;0.01), and EIE (41.86 µm ± 4.95; p&lt;0.01) groups compared to the EC (51.37 µm ± 3.86) group. The data showed that exercise was able to restore muscle trophism in the adult groups; however, none of the protocols has succeeded in aged rats. Conclusion: Immobilization in the shortened position induced muscle atrophy and physical exercise was effective in restoring muscular trophism only in adult animals. Level of Evidence I; Therapeutic studies - Investigating the Results of Treatment.

Standard Strain and Strain Rate by Two-Dimensional Speckle Tracking in Agoutis (Dasyprocta prymnolopha) Anesthetized with Ketamine and Xylazine

Background: The agouti (Dasyprocta prymnolopha, Wagler, 1831) is a wild rodent widely found throughout America which has stood out as a good animal model for scientific investigations. The aim of this study was to study the cardiovascular function of chemically contained agoutis, by performing echocardiographic examinations and measuring Strain and Strain Rate by Speckle Tracking to obtain reference values for the species and verify the applicability of these animals as models for the study of cardiovascular changes in humans.Materials, Methods &amp; Results: It was selected 16 animals, sedated by the combination of ketamine hydrochloride and xylazine and submitted to transthoracic echocardiography. To obtain the standard measurements, B, M and Doppler mode images were taken. The analysis of the radial and longitudinal myocardial deformation of the left ventricle was carried out. The right parasternal window was used for access to the short cardiac axis and the left for access to the long axis. Six radial profiles of strain (ST) and Strain rate (SR) values were obtained, corresponding to the mean of the values for each segment. A total of 18 myocardial segments were analyzed for each specimen and the mean values were used to compose the statistical analysis. The comparison of the means between the genders did not show statistical difference, being the other statistical treatments based on the total sample of 16 animals. The variables that showed statistically significant correlation coefficients in relation to weight were: LA, LA/AO, HR, AVmax, E’ wave, E/IVRT (P &gt; 0.05). HR showed a positive correlation with IVSd (r = 0.51), EPSS (r = 0.55) and E’ wave (r = 0.68); negative with IVRT (r = - 0.41), A wave (r = - 0.54), AVmax (r = - 0.53) and Pmax (r = - 0.65).Discussion: Although presumptively normal echocardiographic values were reported for not anesthetized agoutis, this was the first study to show the measurement of these variables for chemically contained agoutis, in addition to the use of Strain and strain rate by speckle tracking in the assessment of cardiac function. The sudden exposure of an external stimulus (environmental or physical) to which the body is not adapted can trigger an acute stress, and its effects may interfere significantly in the measurement of hemodynamic variables, justifying the need for chemical containment. The values found for the thickness of agoutis cardiac walls and chambers obtained in M mode, both in systole and in diastole, when compared with mammals of different size, confirm the positive linear correlation between body weight and cardiac dimensions for the various evaluated parameters. The velocity obtained by the Strain radial for the apical systolic peak was slightly lower than that obtained for the basal systolic peak, while the opposite was observed for the circumferential Strain, which showed apical peak greater than the basal peak, also to the found for human beings. The values obtained for circumferential, radial and longitudinal strain for agoutis were within the ranges of normality observed in healthy domestic animals and humans.

Evaluation of total intravenous anesthesia with ketamine–xylazine combined with either midazolam or high or low dose propofol in horses: cardiopulmonary effects and recovery characteristics

Introduction: Cardiopulmonary and recovery characteristics of horses administered total intravenous anesthesia (TIVA) with ketamine and xylazine plus midazolam or propofol at two dosages were evaluated.

Chemical Immobilization of Free-ranging Yellow Armadillos (Euphractus sexcinctus) for Implantation of Intra-abdominal Transmitters.

Free-ranging yellow armadillos (Euphractus sexcinctus) from the Brazilian Pantanal were captured for surgical implantation of intra-abdominal radio transmitters. During March 2014, 11 animals were chemically immobilized with a combination of intramuscular ketamine hydrochloride, xylazine hydrochloride, midazolam maleate, and atropine sulfate. The mean induction time and initial heart rate in males was higher than in females. The sex of armadillos did not affect the respiratory rate, which increased from the beginning to end of the monitoring time. The rectal temperatures of females remained almost unchanged, whereas the rectal temperatures of males suffered a slight drop through the procedure. The mean (±SD) total surgical time was 50±6.5 min, and the total anesthetic recovery time was 2.5±0.5 h. The armadillos were monitored for 24 h after surgery and released at their capture site. The anesthetic association was effective, promoting muscle relaxation and analgesia that allowed the performance of surgical procedures.

Intravital investigation of rat mesenteric small artery tone and blood flow.

Substantial information on rat mesenteric small artery physiology and pharmacology based on in vitro experiments is available. Little is known about the relevance of this for artery function in vivo. We here present an intravital model where rat mesenteric small artery diameters are studied under isolated and controlled conditions in situ with simultaneous measurement of blood flow. The responses of the isolated arteries vary with the anaesthetic used, and they are quantitatively but not qualitatively different from the responses seen in vitro. Functional characteristics of rat mesenteric small arteries (internal diameter ∼150-200μm) have been extensively studied in vitro using isometric and isobaric myographs. In vivo, precapillary arterioles (internal diameter <50μm) have been studied, but only a few studies have investigated the function of mesenteric small arteries. We here present a novel approach for intravital studies of rat mesenteric small artery segments (∼5mmlong) isolated in a chamber. The agonist-induced changes in arterial diameter and blood flow were studied using video imaging and laser speckle analysis in rats anaesthetized by isoflurane, pentobarbital, ketamine-xylazine, or by a combination of fentanyl, fluanison and midazolam (rodent mixture). The arteries had spontaneous tone. Noradrenaline added to the chamber constricted the artery in the chamber but not the downstream arteries in the intestinal wall. The constriction was smaller when rats were anaesthetized by rodent mixture in comparison with other anaesthetics, where responses were qualitatively similar to those reported in vitro. The contraction was associated with reduction of blood flow, but no flow reduction was seen in the downstream arteries in the intestinal wall. The magnitude of different endothelium-dependent relaxation pathways was dependent on the anaesthesia. Vasomotion was present under all forms of anaesthesia with characteristics similar to in vitro. We have established an intravital method for studying the tone and flow in rat mesenteric arteries. The reactivity of the arteries was qualitatively similar to the responses previously obtained under in vitro conditions, but the choice of anaesthetic affects the magnitude of responses.

The effect of anesthetic drug choice on accuracy of high-definition oscillometry in laterally recumbent horses

ObjectiveTo determine the accuracy of high-definition oscillometry (HDO) for arterial pressure measurement during injectable or inhalation anesthesia in horses. Study designProspective, clinical study. AnimalsTwenty-four horses anesthetized for procedures requiring lateral recumbency. MethodsHorses were premedicated with xylazine, and anesthesia induced with diazepam–ketamine. Anesthesia was maintained with xylazine–ketamine–guaifenesin combination [TripleDrip (TD; n = 12) or isoflurane (ISO; n = 12)]. HDO was used to obtain systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures, and heart rate (HR) using an 8-cm-wide cuff around the proximal tail. Invasive blood pressure (IBP), SAP, MAP, DAP and HR were recorded during HDO cycling. Bland–Altman analysis for repeated measures was used to compare HDO and IBP for all measurements. The generalized additive model was used to determine if means in the differences between HDO and IBP were similar between anesthetic protocols for all measurements. ResultsThere were >110 paired samples for each variable. There was no effect of anesthetic choice on HDO performance, but more variability was present in TD compared with ISO. Skewed data required log-transformation for statistical comparison. Using raw data and standard Bland–Altman analysis, HDO overestimated SAP (TD, 3.8 ± 28.3 mmHg; ISO, 3.5 ± 13.6 mmHg), MAP (TD, 4.0 ± 23.3 mmHg; ISO, 6.3 ± 10.0 mmHg) and DAP (TD, 4.0 ± 21.2 mmHg; ISO, 7.8 ± 13.6 mmHg). In TD, 26–40% HDO measurements were within 10 mmHg of IBP, compared with 60–74% in ISO. Differences between HDO and IBP for all measurements were similar between anesthetic protocols. The numerical difference between IBP and HDO measurements for SAP, MAP and DAP significantly decreased as cuff width:tail girth ratio increased toward 40%. Conclusion and clinical relevanceMore variability in HDO occurred during TD. The cuff width:tail girth ratio is important for accuracy of HDO.

Evaluating anesthetic protocols for functional blood flow imaging in the rat eye

The purpose of this study is to evaluate the suitability of five different anesthetic protocols (isoflurane, isoflurane–xylazine, pentobarbital, ketamine–xylazine, and ketamine–xylazine–vecuronium) for functional blood flow imaging in the rat eye. Total retinal blood flow was measured at a series of time points using an ultrahigh-speed Doppler OCT system. Additionally, each anesthetic protocol was qualitatively evaluated according to the following criteria: (1) time-stability of blood flow, (2) overall rate of blood flow, (3) ocular immobilization, and (4) simplicity. We observed that different anesthetic protocols produced markedly different blood flows. Different anesthetic protocols also varied with respect to the four evaluated criteria. These findings suggest that the choice of anesthetic protocol should be carefully considered when designing and interpreting functional blood flow studies in the rat eye.

Chronobiological perspectives on myocardial electrophysiological parameters under three types of general anaesthesia in a rat model

The specific aim of the present study, with respect to dependence on the light–dark (LD) cycle under in vivo conditions in spontaneously breathing rats was to review initial state in electrophysiological parameters that may predict the development of heart rhythm disorders in pentobarbital (40 mg/kg), ketamine–xylazine (100 + 15 mg/kg) and zoletil (30 mg/kg) anaesthetized animals. The study was performed using female Wistar rats that were adaptated to an LD cycle (12 h:12 h). Heart rate, PQ and QT intervals were evaluated for their dependence on the LD cycle. The longest PQ interval duration is under zoletil anaesthesia in the light period and the longest QT interval duration is under ketamine–xylazine anaesthesia in both light periods. We concluded that the most significant predisposition toward the development of ventricular arrhythmias originating from disorders of impulse production and conduction occurred under zoletil anaesthesia in the light period; those resulting from disorders in the dispersion of refractory periods occurred under ketamine–xylazine anaesthesia in both the light periods.

Comparison of Physiological Parameters and Anaesthesia Specific Observations during Isoflurane, Ketamine-Xylazine or Medetomidine-Midazolam-Fentanyl Anaesthesia in Male Guinea Pigs.

Guinea pigs (GPs) are difficult to anaesthetize successfully, the choices for anaesthesia are limited and physiological parameters are likely to be influenced substantially under anaesthesia. We implanted blood pressure radio-telemetry devices into 16 male GPs and subjected them to anaesthesia with ketamine-xylazine (KX), medetomidine-midazolam-fentanyl (MMF) or isoflurane (Iso, plus atropine premedication) in a randomized order with a 7 day interval between anaesthesias. Each anaesthesia lasted 40min, after which Iso was discontinued, MMF was fully antagonized with atipamezole-flumazenil-naloxone and KX was partially antagonized with atipamezole. Hemodynamics were recorded continuously for at least 240min after induction and the GPs were monitored for respiratory rate, reflex responses and specific observations until regaining of their righting reflex (RR). Blood for glucose testing was taken from the ear at 7.5, 20 and 40min during anaesthesia. Recovery time was short with MMF and Iso but long for KX. MMF induced only a transient blood pressure drop after antagonization, whereas Iso caused a marked hypotension during maintenance and KX led to moderate hypotension after antagonization. MMF and Iso produced tolerable heart rate changes, but KX led to long term post-anaesthetic bradycardia. Hypothermia occurred with all anaesthesias, but the GPs returned to normothermia the fastest under MMF, followed shortly by Iso. KX, however, caused a profound and prolonged hypothermia. The respiration was depressed with all anaesthesias, substantially with MMF (-41%) and KX (-52%) and severe during Iso maintenance (-71%). Blood glucose with MMF and KX increased throughout the anaesthesia, but the values remained within reference values with all anaesthetics. The reflex responses character and strength varied between the anaesthetics. In conclusion, MMF is the anaesthetic of choice and Iso may be used for short, non-painful procedures. We advise against the use of KX in GPs.

Long-lasting behavioral effects in neonatal mice with multiple exposures to ketamine-xylazine anesthesia

Anesthetic agents are often administered in the neonatal period, a time of rapid brain development and synaptogenesis. Mounting evidence suggests that anesthetics can disrupt neurocognitive development, particularly in cases of multiple or prolonged anesthetic exposure. Previous studies have shown that administering multiple doses of ketamine-xylazine (KX) anesthesia to neonatal mice can induce long-term changes to synaptic plasticity in the cortex, but the effect on neurocognitive function remains unclear. In this study, we exposed neonatal mice to single dose and multiple doses of KX anesthesia in the neonatal period (postnatal days 7, 9, 11), and conducted a series of behavioral tests in young adulthood (1month of age). Mice receiving multiple doses of KX anesthesia showed deficits in novel object recognition, sociability, preference for social novelty and contextual fear response, but no effect on auditory-cued fear response. Single dose of KX anesthesia had no effect on these behaviors except for contextual fear response. We also observed that multiple exposures to KX anesthesia were associated with decreased CaMKII phosphorylation, which is known to play a role in synapse development and long-term potentiation, likely contributing to learning impairment.

Electrochemical Manipulation of Living Cells Supported By Polymeric Nanosheets

Introduction Regenerative medicine based on cell sheets has been widely investigated. Developing an effective and minimally invasive cell transplantation process is an important enabling step for such medical treatments. However, cell sheets are fragile and handling them is difficult. Recently, we have investigated the use of biodegradable polymeric nanosheets for introducing cells into the body and found that the flexible nanosheets on which cells are cultured can be aspirated and injected by a syringe needle without significant loss of cell viability. To harvest cell/nanosheet constructs from a substrate, a water soluble sacrificial layer such as polyvinyl alcohol (PVA) was used, however, a drawback in this method is that the timing to detach the cell/nanosheet constructs from the substrate cannot be controlled. In this paper, we use an electrochemical method for harvesting the cell/nanosheet constructs in vitro. Cells are cultured on nanosheets attached on a self-assembled monolayer (SAM) of alkanethiol. The SAM is reductively desorbed from the gold substrate by the application of a negative electrical potential, which detaches the cell/nanosheet constructs from the gold surface in a rapid manner. The harvested cell/nanosheet constructs were transplanted into the subretinal space of rat eyes through syringe needles. Material and Method A gold layer was patterned by sputter-depositing gold with a patterned silicon mask. The gold surface was modified with 10-carboxy-1-decanethiol, 7-carboxy-1-heptanethiol or L-cysteine by immersing the substrates in any of the three thiol solutions for 30 min at room temperature. The desorption of the SAMs was performed and analyzed electrochemically. Nanosheets were first prepared on PVA-coated substrates by a combination of a spincoating and microcontact printing technique using poly(dimethyl siloxane) (PDMS) stamps. A solution of poly(lactic-co-glycolic acid) (PLGA) was spincoated onto the PDMS stamp and the resulting PLGA layer was transferred onto a PVA-coated substrate. Freestanding nanosheets were obtained by dissolving the PVA sacrificial layer with water and attached on the SAM-modified gold surface. To desorb the nanosheets with SAMs, a voltage of 1.5 V, supplied by an AA-size dry battery, was applied between the gold electrode (cathode) and the Pt wire (anode) in phosphate buffered saline. Retinal pigment epithelium (RPE) cells were cultured on PLGA nanosheets attached on the SAMs for 2 days to form cell/nanosheet constructs. Electrochemical desorption of SAMs with cell/nanosheet constructs was conducted in culture medium. Sprague-Dawley rats (SLC) weighing 250-300 g were used in this study. After the rats were anesthetized with ketamine hydrochloride and xylazine hydrochloride, RPE cell/nanosheet constructs were injected into the subretinal space using a hand-made glass capillary needle. Result and Discussion Cyclic voltammograms observed in the reductive desorption of SAMs showed a clear dependence of peak potential on the length of the alkyl chain. With longer chains, the peak potential shifted to the negative direction, which has been explained by van der Waals interactions between the alkyl chains. Since the SAM of L-cysteine was reductively desorbed at a lower potential (around -0.7 V vs. Ag/AgCl) than the SAM of the two other thiol molecules and L-cysteine is biocompatible, the SAM of L-cysteine was used for harvesting nanosheets and cell/nanosheet constructs. PLGA nanosheets attached on the SAM of L-cysteine were successively detached from the substrate by gently pipetting within 1 min after applying the reductive potential to the gold electrode. On the other hand, nanosheets on the SAM without applying the voltage did not detach from the substrate. In a similar manner, RPE cell/nanosheet constructs could be detached from the substrate and the live/dead staining showed the cells on the nanosheets are viable. Finally, we used our system to deliver RPE cell/nanosheet constructs to the subretinal space of a rat eye in vivo. Nanosheets were injected with 2 μL of saline to the subretinal space through the sclera using a glass capillary needle. Optical coherence tomography (OCT) images of the retina taken one week after the injection of the nanosheets showed a shadow of the sheet like structure in the subrentinal space while there was not such shadow in the OCT image of a control. Also, a shadow of the circular nanosheet was observed at the posterior segment of the isolated eye. These results indicate that the nanosheets were successfully injected and spread into the subretinal space of rat eyes. Conclusion We reported a method for noninvasively harvesting cell/nanosheet constructs from a culture surface by using the electrochemical desorption of SAM. The harvested RPE/nanosheet constructs could be delivered to the subretinal space using a capillary needle. The harvesting and delivering system of cell/nanosheets constructs could be a useful tool for cell transplantation.

Drug Delivery System Using Injectable Polymeric Sheets

Introduction Designing drug-delivery systems (DDS) targeting a local specific organ in the body, e.g., the bladder and the subretinal structure, is one of the most challenging tasks. Ideally, DDS devices are to be less-invasive as much as possible. Given the conventional DDS devices, DDS microspheres are superior in terms of less-invasive by injection but they cannot be located at the affected area. On the other hand, sheet-type DDS devices require surgical procedure to be retained in the body while they can delivery drug for long-term at affected area. Therefore, development of DDS devices that can be injected and located at the affected area for long-term drug release would bring significant benefits. In this study, we report on an injectable sheet-type DDS device by embedding DDS microspheres in polymeric sheets. The developed device was characterized in vitro and also evaluated in vivo by implanting it into rat eyes. Material and Method Collagen microspheres (COLs) were prepared by water-in-oil emulsion method. Next, COLs were immersed in solution of a model drug FITC-dextran (FD-40). The devices were made by photopolymerization with UV light of mixtures of polyethylene glycol dimethacrylate (PEGDM), a photopolymerization initiator and COLs. The devices were observed by SEM and fluorescence microscope to examine the distribution of COLs in PEGDM. In vitro release study was carried out to reveal release characteristics. To estimate the amounts of FD-40 that had diffused out of the devices, the devices were immersed in 3 mL of PBS and incubated at 37 C. The fluorescent intensities of the PBS solutions were measured spectrofluorometrically. PEGDM sheets of different thickness were photopolymerized with UV light. They were rounded several times around a glass cylindrical shape and the deployment times were measured in water in order to examine self-deployment characteristics. For in vivo experiments, Sprague-Dawley rats (SLC) weighing 250-300 g were used. After the rats were anesthetized with ketamine hydrochloride and xylazine hydrochloride, the FITC-albumin-loaded device was implanted on the sclera of rats and the fluorescence distribution at the posterior segment of the eye was evaluated. Result and Discussion A sheet type DDS device that consists of COLs and PEGDM sheet was fabricated. COLs were uniformly distributed in the device and a part of COLs was exposed on the surface of the device. The density of COLs in the device was proportional to the concentration of COLs in the corresponding unpolymerized PEGDM/COL mixture. In vitro release study confirmed that devices could release FD-40 continuously over 4 weeks, though the release of FD-40 could not be observed from PEGDM sheets in which FD-40 was directly loaded without the use of COLs. The results indicate that the drug diffuses through interconnected COLs in the device. PEGDM sheets showed a linear relationship between deployment time and the number of turns of the sheet. Also, the device could be injected in water through a syringe needle and then fully expanded. In vivo experiments showed that the device adhered on the sclera without suturing. Also, the fluorescence could still be detected in the sclera and retina even 4 weeks after the implantation of the device, indicating the transscleral delivery of the drug to the retina. Conclusion We developed an injectable sheet type DDS device consisting of COLs and PEGDM sheet, which can continuously release a model drug over 4 weeks. The device could implanted on the sclera of rat eyes and indicated the possibility of the transscleral delivery of the drug to the retina.

&lt;b&gt;Interaction between low level laser therapy and anesthesia in wistar rats

The aim was to assess whether the low level laser therapy (LLLT), 660 nm, can lower the effect of injectable anesthetics in rats. Wistar rats (n = 20) were used in two steps: 1) grip strength test and measuring the anesthesia time for control (G1A) and irradiated (G1AL) groups; 2) after 15 days, rats received new anesthesia injection and were evaluated for nociception (G2A - control; G2AL - laser). Anesthesia was induced by ketamine hydrochloride (75 mg kg -1 ) and xylazine (10 mg kg -1 ), by intraperitoneal injection, according to the body weight. LLLT used was 660 nm at four sites along the right hind limb. Anesthesia time was shorter for the G1AL (p = 0.0031). There were significant differences between pre- and post-intervention in the grip strength test (p 0.05). It can be concluded that the LLLT caused no significant reduction on the effect of anesthesia.