Sparing effect of tramadol,lidocaine, dexmedetomidine and their combination on the minimum alveolar concentration of sevoflurane in dogs

BackgroundProblems associated with using inhalational anaesthesia are numerous in veterinary anaesthesia practice. Decreasing the amount of used inhalational anaesthetic agents and minimising of cardiorespiratory disorders are the standard goals of anaesthetists.ObjectiveThis experimental study was carried out to investigate the sparing effect of intravenous tramadol, lidocaine, dexmedetomidine and their combinations on the minimum alveolar concentration (MAC) of sevoflurane in healthy Beagle dogs.MethodsThis study was conducted on six beagle dogs. Sevoflurane MAC was determined by the tail clamp method on five separate occasions. The dogs received no treatment (control; CONT), tramadol (TRM: 1.5 mg kg^-1 intravenously followed by 1.3 mg kg^-1 h^-1), lidocaine (LID: 2 mg kg^-1 intravenously followed by 3 mg kg^-1 h^-1), dexmedetomidine (DEX: 2 μg kg^-1 intravenously followed by 2 μg kg^-1 h^-1), and their combination (COMB), respectively. Cardiorespiratory variables were recorded every five minutes and immediately before the application of a noxious stimulus.ResultsThe COMB treatment had the greatest sevoflurane MAC-sparing effect (67.4 ± 13.9%) compared with the other treatments (5.1 ± 25.3, 12.7 ± 14.3, and 40.3 ± 15.1% for TRM, LID, and DEX treatment, respectively). The cardiopulmonary variables remained within the clinically acceptable range following COMB treatment, although the mean arterial pressure was higher and accompanied by bradycardia.ConclusionsTramadol-lidocaine-dexmedetomidine co-infusion produced a remarkable sevoflurane MAC-sparing effect in clinically healthy beagle dogs and could result in the alleviation of cardiorespiratory depression caused by sevoflurane. Cardiorespiratory variables should be monitored carefully to avoid undesirable side effects induced by dexmedetomidine.     

Color vision, spectral sensitivity, accommodation, and visual acuity in juvenile masu salmon Oncorhynchus masou masou

ABSTRACT:   Color vision, spectral sensitivity, accommodation, and visual acuity were examined in juvenile masu salmon Oncorhynchus masou masou to obtain fundamental information about the visual system. Two types of S-potentials were recorded from 415 horizontal cells in isolated retinas from 34 cultured freshwater masu salmon (114–219 mm standard length, SL). Although horizontal cells recording S-potentials were not identified, the horizontal cells were confirmed because their responses were maintained while the stimulus remained. The variety of chromaticity (C)-type S-potentials indicated well-developed color vision. The analysis of the luminosity (L)-type S-potentials indicated that the peak spectral sensitivity was at 522 nm. S-potentials were also recorded in response to ultraviolet light. The direction and extent of lens movement induced by electrical stimulation was measured in 12 cultured masu salmon (99.0–142.5 mm SL). The results indicated that the visual axis was upward and forward, and that the range of accommodation was from 0.79 × SL in front of the eye to infinity. In histological analysis of the retinas of five wild smolts (100–118 mm SL), the maximum cone densities (276–345 cones/0.01 mm²) were detected in the ventral to temporal regions. The visual acuities assessed by histological methods were 0.069–0.075.     

In vitro detection of equine arteritis virus from seminal plasma for identification of carrier stallions

Equine arteritis virus (EAV) was readily isolated in RK-13 cell monolayers by plaque assay from seminal plasma of experimental carrier stallions when they contained high titers of virus regardless of the presence of non-viral cytotoxicity in the seminal plasma. The cytotoxicity interfered with virus isolation from seminal plasma which contained virus at titers less than 10 PFU/ml. However, it was possible to detect the virus in seminal plasma pretreated with PEG (#6000). EAV was consistently identified by RT-PCR from crude seminal plasma which contained virus at titers of more than 10(2.7) PFU/ml. In vitro detection of EAV by virus isolation supplemented with RT-PCR using seminal plasma was proved to be an effective alternative to the standard test mating as a diagnostic method for carrier stallions.     

Development of wooden portal frame structures with improved columns

In Japan, the lifetime cycle of most housing lasts around 20–30 years. A governing factor in this respect is poor durability due to old-fashioned use of the house. As a solution of this problem, houses can be built with a skeleton structure that allows free partition of spaces by future owners. To develop the skeleton structure effectively, multistory frames with spans of 6 to 10 m are required. For this reason, attention has been focused on the behavior of multistory timber frame structures. In this article, two types of wooden portal frame structures are proposed. Both structures have improved vertical columns with short horizontal members glued in. The aim of this study was to investigate structurally effective solutions with these types of columns. The first type of the new structure changed the location of the moment-transmitting ductile connection with the improved columns. The second type of structure used an extended panel zone. Nine portal frame specimens were tested. The stiffness values were improved by around 1.7 and 3.5 times when compared with the control, and the strength was improved by around 1.25 and 1.45 times.     

Dynamic excitation and static loading tests of glulam lattice floor

A wooden lattice floor with high stiffness and damping capacity has been developed to solve noise problems in wooden apartment houses. The lattice floor consisted of Douglas fir glulam beams with inserted steel plate joints and drift pins. To examine the structural performance of the floor, dynamic excitation and static loading tests were conducted on the full size floor. The first and second order resonance frequencies of the floor were 13.5Hz and 27.0Hz, respectively. These frequencies are similar to the peak frequency of a conventional wooden floor and the combined floor fabricated from glued laminated timber and iron. The maximum static load of the floor was 127kN. The apparent flexural rigidity was less than half the value of several floors studied in the past. However, it is considered that the stiffness is improved by constructing panels and this floor has almost equivalent performance. Relative deflection was not affected by the loading history.Part of this study was presented at the International Wood Engineering Conference, New Orleans, October 1996.     

On mechanical behavior of traditional timber shear wall in Taiwan I: background and theory derivation

The objectives of this study were to explore the mechanical behavior of traditional timber shear walls in Taiwan and to propose a theoretical model to predict their lateral force resistance. An extensive field investigation was conducted, and the dimensions, tectonic detail, and materials used were recorded. The data collected were used as the reference for theoretical derivation and experimental design. In the theoretical model, the moment resistance of entire shear walls was derived from the contributions of the moment-resisting capacity supplied not only by embedment and friction action between board units and beams but also the dowel action of bamboo nails. Timber shear walls with various geometric conditions and material properties are considered. The theoretical model demonstrated in this study can be used to predict the mechanical behavior of timber shear walls and will be verified by experiments in our next article.     

Bearing properties of engineered wood products I: effects of dowel diameter and loading direction

The embedment tests of laminated veneer lumber (LVL) with two moduli of elasticity (MOE; 7.8 GPa and 9.8GPa), parallel strand lumber (PSL), and laminated strand lumber (LSL) were conducted in accordance with ASTM-D 5764. The load-embedment relation for each of these engineered wood products (EWPs) was established. The directional characteristics of bearing strength (_e), initial stiffness (k _e), and effective elastic foundation depth were obtained from the tested results. The effective elastic foundation depth (=E/k _e,E = MOE), based on the theory of a beam on elastic foundation, was obtained from thek _e and MOE. An of 90° (perpendicular to the grain) was calculated by dividingE ₉₀ [MOE of 90° from the compression test, but MOE of 0° (E ₀), parallel to the grain, obtained from the bending test] byk _e90, the initial stiffness of 90°. This study aimed to obtain the bearing characteristics of each EWP, taking into consideration their anisotropic structures, for estimating the fastening strength of a dowel-type fastener. The relations between the bearing coefficients ( _e,k _e,) on the loading direction and dowel diameter were established from the load-embedment curves. Based on the results of the embedment test, tested EWPs showed different tendencies in all directions from wood and glued laminated timber.Part of this study was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

The pharmacological effects of the anesthetic alfaxalone after intramuscular administration to dogs

The pharmacological effects of the anesthetic alfaxalone were evaluated after intramuscular (IM) administration to 6 healthy beagle dogs. The dogs received three IM doses each of alfaxalone at increasing dose rates of 5 mg/kg (IM5), 7.5 mg/kg (IM7.5) and 10 mg/kg (IM10) every other day. Anesthetic effect was subjectively evaluated by using an ordinal scoring system to determine the degree of neuro-depression and the quality of anesthetic induction and recovery from anesthesia. Cardiorespiratory variables were measured using noninvasive methods. Alfaxalone administered IM produced dose-dependent neuro-depression and lateral recumbency (i.e., 36 ± 28 min, 87 ± 26 min and 115 ± 29 min after the IM5, IM7.5 and IM10 treatments, respectively). The endotracheal tube was tolerated in all dogs for 46 ± 20 and 58 ± 21 min after the IM7.5 and IM10 treatments, respectively. It was not possible to place endotracheal tubes in 5 of the 6 dogs after the IM5 treatment. Most cardiorespiratory variables remained within clinically acceptable ranges, but hypoxemia was observed by pulse oximetry for 5 to 10 min in 2 dogs receiving the IM10 treatment. Dose-dependent decreases in rectal temperature, respiratory rate and arterial blood pressure also occurred. The quality of recovery was considered satisfactory in all dogs receiving each treatment; all the dog exhibited transient muscular tremors and staggering gait. In conclusion, IM alfaxalone produced a dose-dependent anesthetic effect with relatively mild cardiorespiratory depression in dogs. However, hypoxemia may occur at higher IM doses of alfaxalone.