2010 - Volume 37 - Issue 3

141-146
Standard Surgical Technique for Applying Rod Through Plate (RTP) Internal Fixator – An Experimental Study in Sheep
by Garri Tralman, Vladimir Andrianov, Neeme Talvi, Andres Arend, Piret Männik, Denis Uksov & Marina Aunapuu

The standard surgical technique for applying a rod through plate (RTP) internal fixator to treat long bone fractures was carried out. The experiments were performed in 4 male Estonian Blackhead sheep. Previously, a RTP fixator for small animal fracture repair has been tested experimentally in rabbits and also on clinical cases in dogs. To reduce complications such as screw loosening and rod displacement, modification to the original fixator was made: one locking screw on each rod was added to fix the rod to the plate. In this study the healing process of tibial osteotomies using the modified RTP fixator was evaluated in sheep. Sheep were used as experimental animals because body weight and bone structure is similar to small animals.

149-156
The Fracture Stress of Rat Achilles Tendons
by P. E. Chatzistergos, S. I. Tsitsilonis, A. S. Mitousoudis, D. N. Perrea, A. B. Zoubos & S. K. Kourkoulis

For the determination of the fracture stress of soft tissues both the fracture force and the cross sectional area are required. For short tissues these prerequisites are difficult experimental tasks. The determination of the fracture force necessitates proper gripping without damaging the tissues or altering their properties. In order to meet this challenge the rapid-freezing technique was employed, modified to ensure that the tendon was not frozen. On the other hand an accurate value of the cross sectional area of short soft tissues is difficult to be obtained using conventional techniques. In this context a novel procedure is proposed here based on the histologically-measured cross-sectional area of the dehydrated tendon after the biomechanical testing. Combination of these solutions permitted the performance of tension tests for rat Achilles tendons and calculation of their fracture stress. The values of the Achilles tendon failure stress, as estimated above, exhibited considerably lower scattering compared to those of the fracture forces.

159-169
Improved Animal Model for Vibration Injury Study
by Ji-Geng Yan, Lin-Ling Zhang, Yuhui Yan, James R. Sanger, Eric S. Jensen & Hani S. Matloub

Hand-Arm Vibration Syndrome is a debilitating condition that affects millions of power-tool users in the U.S. Research into its etiology has been hampered by deficiencies in animal models used for vibration studies. Our objective was to design an animal vibration injury model that: 1) vibrates only the studied limb, not the body; and 2) avoids anaesthesia, thus allowing purer focus on physiological effects of vibration while reducing pain and distress for the animals, thereby enhancing their well-being. We compared advantages and disadvantages of several models, studying body temperature, body weight, tissue perfusion, vascular pathohistology, and general animal condition. Our model uses an apparatus that limits vibration to one body part and a specially designed cage that minimizes animal stress and suffering, eliminating the need for anaesthesia. It is ideal for the study of vibration injury, providing tissue damaged purely by vibration that can be used for pathohistology and biochemical study.

173-182
Histopathology of the Hematopoietic Bone Marrow in the Temporomandibular Joint of Rats Subjected to Undernutrition and to Mandibular Condyle Fracture
by Luciana Corrêa, Rita Haber Rami, Lucimar Rodrigues, Karen Nata Hiraki & João Gualberto de C. Luz

Undernutrition can cause important functional and morphological alterations in the hematopoietic bone marrow (HBM). Degeneration of the HBM in malnourished individuals has been observed in the long bones, but none has been described in the cranial bones. Mandibular condyle fracture can lead to determine nutritional effects due to the high catabolism needed for the bone healing added to the difficulties of mastication. The aim of this study is to describe the histological aspect of HBM in the fractured mandibular condyle and in the temporal bone of malnourished rats. Thirty adult rats suffered unilateral mandibular condyle fracture and were divided into well-nourished (FG) and malnourished (MG) groups. In the MG the animals received a hypoproteic diet during the experiment. Histological sections of the temporomandibular joint were stained to visualize and quantify the HBM in this region at 24h, and 7, 15, 30, and 90 days postfracture. At 24 hours, FG and MG showed hypocellularity and ischemic degeneration in the mandibular condyle and in the temporal bone. At 7 days, FG exhibited high cellularity in comparison with MG in the condyle; the temporal bone of both groups presented hypocellularity and degeneration. At 30 and 90 days, FG exhibited similar characteristics to those of the control; MG maintained the degeneration level mainly in the temporal bone. Malnutrition prejudices the regeneration of the HBM during a fracture healing in the temporomandibular joint. This fact contributes to a complete modification of the bone structure as well as to an impairment of the healing process.

185-201
Impact of Cage Size and Enrichment (Tube and Shelf) on Heart Rate Variability in Rats
by Anna E. Brauner, David T. Kurjiaka, Angela Ibragimov & Ann L. Baldwin

Rats respond physiologically and behaviorally to environmental stressors. As cage conditions can be a stressor, it is important that experimental results acquired from caged rats are not confounded by these responses. This study determined the effects of cage size and cage enrichment (tube and shelf) on heart rate variability (HRV) in rats as a measure of stress. Electrocardiogram data were collected from 5 male Sprague-Dawley rats, each implanted with a radio-telemetric transducer to assess the ratio of the low to high frequency components of the HRV power spectrum (LF/HF). This ratio reflects the degree of sympathetic versus parasympathetic nervous activity and increases with decreasing HRV. Rats were housed for 3 weeks in each of the following cage conditions: small un-enriched, small enriched, large un-enriched and large enriched. Cage enrichment and/or larger cages did not significantly alter LF/HF values compared to the small, un-enriched cage condition, when considered independent of the sleep/wake cycle. However, when results were pooled for all cage conditions, LF/HF significantly increased during the wake cycle compared to the sleep cycle. Further analysis showed that this difference was only statistically significant for the un-enriched cage condition. Thus the presence of a tube and a shelf in a rodent cage can alter the diurnal rhythm of HRV in rats and this should be taken into account when designing experiments in which HRV is an outcome.

203-210
Effects of Lecithin and Vitamin E Supplementation on Liver Steatosis and Oxidative Stress Induced by Chronic Ethanol Consumption in Rats
by Sheila Cristina de Lima Sanches, Guilherme Vannucchi Portari, Rafael Deminice, Sérgio Zucoloto, Paula Garcia Chiarello, Helio Vannucchi & Alceu Afonso Jordão

Oxidative stress and lipid peroxidation, associated with ethanol, are considered important pathogenic mechanisms in the formation of hepatic steatosis. The objective of the present study was to assess the effects of supplementation with lecithin and vitamin E on the oxidatives stress and hepatic steatosis induced in rats by chronic ethanol consumption. Fifty-two Wistar rats were divided into 4 experimental groups: control (AIN-93 diet), ethanol group (control diet plus a 20% hydroalcoholic solution), ethanol + vitamin E group (addition of 0.6% vitamin E to the diet plus a 20% hydroalcoholic solution); ethanol + soy lecithin group (addition of 5 % soy lecithin to the diet plus a 20% hydroalcoholic solution). At the end of 4 weeks the animals were sacrificed. The results showed a significantly smaller number of animals (p < 0.05) classified as having a low degree of steatosis in the ethanol + vitamin E group and ethanol + soy lecithin group compared to the ethanol group. In addition, the ethanol + soy lecithin group had a significantly lower concentration of hepatic fat (p < 0.05) than the ethanol group. A significant reduction of hepatic TBARS concentration (p < 0.05) was detected in the ethanol + vitamin E group compared to the ethanol group. Hepatic carbonyl concentration was significantly lower in the ethanol + soy lecithin group. However, hepatic GSH was significantly lower in the ethanol + vitamin E and ethanol + soy lecithin groups compared to the control group. In conclusion, supplementation with lecithin and vitamin E attenuated the hepatotoxic effects of chronic ethanol intake and contributed to a reduction of the progression of steatosis status.

213-222
Motor and Behavioural Abnormalities Associated with Persistent Spontaneous Epilepsy in the fvb/n Mouse Strain
by Anabela Silva-Fernandes, Pedro Oliveira, Nuno Sousa & Patrícia Maciel

The FVB/N mouse strain (Mus musculus) is often used for generation of transgenic animals. However, it has also been the object of several studies in epilepsy research due to its increased susceptibility to develop spontaneous and induced seizures and its sensitivity to seizure-triggered neuronal death. We aimed to analyse behavioural changes observed in FVB/N mice that had seizure episodes throughout life. For this, we assessed the behaviour profile of 52-week old FVB/N animals displaying repeated spontaneous seizures, using the SHIRPA protocol. These epileptic mice also displayed a marked gait ataxia and decreased locomotor and exploratory activity. Moreover, these animals weighed less than control mice, and displayed increased signs of aggression and vocalization behaviours. Analysis of the data by clusters showed that in the epileptic mice there were significant deficits in the SHIRPA “spinocerebellar function”, “neuropsychiatric function” and “muscle and lower motor neuron function” scores, suggesting extensive brain damage caused by repeated experience of seizures.

223-229
Evaluation of Xylazine, Acepromazine and Medetomidine with Ketamine for General Anaesthesia in Rabbits
by Amarpal, P. Kinjavdekar, H.P. Aithal, A.M. Pawde, Jasmit Singh & Rahul Udehiya

A randomized, prospective, blinded experimental study was conducted in 32 rabbits of either sex to compare the anaesthetic and physiological effects of ketamine with different pre-anaesthetics. Rabbits were randomly divided into 4 equal groups. Xylazine 6 mg/kg in animals of group xylazine-ketamine (XK), acepromazine 2 mg/kg in animals of group acepromazine-ketamine (AK), medetomidine 125 μg/kg in group medetomidine-ketamine 1 (MK1) or medetomidine 250 μg/kg in group medetomidine-ketamine 2 (MK2) were administered by intramuscular injection (IM). Five minutes later, ketamine 60 mg/kg was administered intramuscularly to all the groups. The rabbits were observed for the onset of weak time, down time, the time to loss of righting reflex, pedal reflexes and response to surgical stimuli. Heart rate, respiratory rate and rectal temperature and arterial oxygen saturation of haemoglobin (SpO2) were recorded up to 60 min. Weak time, down time and time to loss of righting reflex were the shortest in animals of group MK2 as compared to the other groups. Pedal reflexes remained intact in all the animals of XK group, but were abolished in 50% of the AK group, 75% of the MK1 group and 100% of animals in the MK2 group. Pain was evinced during surgery by all the animals in group XK, 5 animals in group AK and 4 animals in group MK1. The best analgesia was achieved in the animals of group MK2, where none of the animals showed pain on surgical stimulation. Heart rate and SpO2 decreased significantly (P<0.01) in the animals of groups XK, MK1 and MK2 but respiratory rate and rectal temperature decreased significantly (P<0.01) in all the groups. However, all the animals recovered from anaesthesia without complications. It was concluded that medetomidine 250 µg/kg and ketamine 60 mg/kg produced excellent anaesthesia to allow pain free surgery and may be considered suitable for anaesthesia in New Zealand White rabbits.