Dorsal Direction Research Articles

Three-Corner Arthrodesis With Scaphoid and Triquetrum Excision for Wrist Arthritis

To report the clinical and radiographic results of a consecutive series of patients who underwent the 3-corner arthrodesis (3CA) (arthrodesis of capitate, hamate, and lunate with scaphoid and triquetrum excision) procedure for wrist arthritis. This was a retrospective study of 30 consecutive patients who underwent a 3CA between 1994 and 2008. The indications were painful wrist osteoarthritis due to stage 2 or 3 scapholunate advanced collapse, scaphoid nonunion advanced collapse, or scaphoid chondrocalcinosis advanced collapse wrists. The clinical assessment consisted of range of motion, grip strength, and the Disabilities of the Arm, Shoulder, and Hand and Patient-Rated Wrist Evaluation scores. The radiographic assessment parameters consisted of bone fusion, carpal height and translation, lunate tilt, and appearance of the radiolunate joint space. The average follow-up was 6 years (± 4 years). The arthrodesis was performed with staples, 2 screws, or a plate and screws. Grip strength was 72% of the contralateral side. The mean range of motion in flexion-extension arc and ulnar-radial deviation arc was 70° and 36°, respectively. The mean Disabilities of the Arm, Shoulder, and Hand and the Patient-Rated Wrist Evaluation scores were 17 (± 11) and 22 (± 24), respectively. The fusion incidence was 90% (27 of 30). The mean difference of radiolunate angle on preoperative and postoperative radiographs was 8° (16°-8° in dorsal direction). The radiolunate joint space had narrowed in 1 patient. Six surgical revisions (20%) were necessary owing to dorsal pain in patients operated using plates, staples, or excessively long screws. Three-corner arthrodesis results are comparable with 4-corner arthrodesis and proximal row carpectomy. We feel that it is simpler technically than 4-corner arthrodesis. Although 3CA is more complex than proximal row carpectomy, it preserves the native radiolunate joint. Complications that can be attributed to the dorsal fixation hardware (particularly staples and plates) were noteworthy. Therapeutic IV.

A comparative study of the effects of vein-joints on the mechanical behaviour of insect wings: I. Single joints

The flight performance of insects is strongly affected by the deformation of the wing during a stroke cycle. Many insects therefore use both active and passive mechanisms to control the deformation of their wings in flight. Several studies have focused on the wing kinematics, and plenty is known about the mechanism of their passive deformability. However, given the small size of the vein-joints, accurate direct mechanical experiments are almost impossible to perform. We therefore developed numerical models to perform a comparative and comprehensive investigation of the mechanical behaviour of the vein-joints under external loading conditions. The results illustrate the effect of the geometry and the presence of the rubberlike protein resilin on the flexibility of the joints. Our simulations further show the contribution of the spikes to the anisotropic flexural stiffness in the dorsal and ventral directions. In addition, our results show that the cross veins, only in one joint type, help to transfer the stress to the thicker longitudinal veins. The deformation pattern and the stress distribution in each vein-joint are discussed in detail. This study provides a strong background for further realistic modelling of the dragonfly wing deformation.

Sex-specific variation in conspecific-acquired marking prevalence among dusky dolphins (Lagenorhynchusobscurus)

Despite logistical challenges that limit direct observations of behavior for some species, physical scars can provide indirect evidence of aggression. Dusky dolphins (Lagenorhynchus obscurus (Gray, 1828)) off Kaikoura, New Zealand, derive most of the notches and scars on their dorsal fins from conspecifics. However, aggressive encounters have rarely been observed in this sexually monomorphic species. If injurious interactions are associated with intrasexual competition among males but not females, we predicted males would have more conspecific-acquired markings than females. High-quality dorsal fin photographs of dolphins of known sex (n = 79) were collected during boat-based surveys off Kaikoura. We measured three quantitative variables (notch height ratio, notch depth ratio, and dorsal fin rake direction) and one qualitative variable that scored the overall prevalence of markings (notches and scars). All four measures yielded consistent results. Males had significantly more conspecific-acquired markings than females. We reject the hypothesis that there is no difference between the sexes in marking prevalence. We propose that brief events of direct competition are missed by observers but recorded in accumulated patterns of conspecific-acquired markings that differ between the sexes.

The preventive effect of topical zafirlukast instillation for peri-implant capsule formation in rabbits.

BackgroundCapsular contracture is the most troublesome complication in breast implant surgery. Although capsule formation can be seen as a normal reaction to a foreign body, it can induce pain, hardness, deformity, and other pathologic problems. Surgical intervention is required in severe cases, but even surgery cannot guarantee a successful outcome without recurrence. This experimental study confirms that single topical administration of leukotriene antagonist zafirlukast (Accolate, Astrazeneca) reduces peri-implant capsule formation and prevents capsular contracture.MethodsTwelve smooth-surfaced cohesive gel implants were implanted in New Zealand White rabbits. These miniature implants were designed to be identical to currently used products for breast augmentation. The rabbits were divided into 2 groups. In the experimental group (n=6), the implant and normal saline with zafirlukast were inserted in the submuscular pocket. In the control group (n=6), the implant and normal saline alone were used. Two months later, the implants with peri-implant capsule were excised. We evaluated capsule thickness and collagen pattern and performed immunohistochemical staining of myofibroblasts, transforming growth factor (TGF)-β1, 2.ResultsThe thickness of the capsules in the experimental group was reduced in both dorsal and ventral directions. The collagen pattern showed parallel alignment with low density, and the number of myofibroblasts as well as the amounts of TGF-β1 and TGF-β2 were reduced in the experimental group.ConclusionsWe suggest that single topical administration of leukotriene antagonist zafirlukast can be helpful in reducing capsule formation and preventing capsular contracture via myofibroblast suppression, modulation of fibroblastic cytokines, and anti-inflammatory effect.

Mechanics of Optic Vesicle Morphogenesis in the Chick Embryo

In the vertebrate embryo, the eyes are initially bulges that grow outward from the sides of the primitive forebrain. As these optic vesicles (OVs) elongate, they come into contact with the surrounding surface ectoderm (SE), and both layers then invaginate to create the optic cup (prospective retina) and lens vesicle. The initial shaping of the OVs sets the stage for these later events. To explore the mechanical factors involved in shaping the OVs, we used experiments on chick embryos along with computational models. First, mechanical dissections were used to remove the SE. Our analysis of OV shapes suggests that the SE exerts asymmetric loads that cause the OVs to flatten and shear caudally during the earliest stages of eye development and later to bend in the caudal and dorsal directions. These deformations cause the initially spherical OVs to become pear-shaped. Exposure to the myosin II inhibitor blebbistatin reduced these effects, suggesting that cytoskeletal contraction controls OV shape by regulating tension in the SE. To test the physical plausibility of these interpretations, we developed finite-element models of the forebrain, including frictionless contact between the SE and OVs. With differential growth included in the OVs, these models were used to simulate each experiment (control, SE removed, no contraction). For each case, the predicted shape of the OV agrees reasonably well with experiments. Our results support this idea that a combination of differential growth in the OV and external pressure exerted by the SE are sufficient to cause the global changes in OV shape observed during the earliest stages of eye development.

J2320104 走行動作における下肢の関節反力・関節モーメント及び筋活動に関する研究

In this paper, two foot strike pattern, which are the rear foot strike (RFS) and the fore foot strike (FFS), are compared from the viewpoint ofthe joint moment, joint reaction force and muscle activity using the actual measurement of running for two subjects. As the results, the landing impact force has two peaks for RFS while one peak for FFS, and the significant features can be observed in the ankle joint rather than the knee and hip joint. The joint moment of the ankle joint for RFS acts toward the dorsal flexion direction at the beginning of landing, and then toward the plantar flexion direction, while the one for FFS acts toward the plantar flexion direction during landing. The bone-on-bone force for RFS shows two peaks as similar with the landing impact force. For RFS, the Tibialis anterior much works while for FFS, the Gastrocnemius and the Soleus works much. Moreover, the differences of subject A and B are shown as the contribition of joints on the running.

Mechanical effects of the surface ectoderm on optic vesicle morphogenesis in the chick embryo

Precise shaping of the eye is crucial for proper vision. Here, we use experiments on chick embryos along with computational models to examine the mechanical factors involved in the formation of the optic vesicles (OVs), which grow outward from the forebrain of the early embryo. First, mechanical dissections were used to remove the surface ectoderm (SE), a membrane that contacts the outer surfaces of the OVs. Principal components analysis of OV shapes suggests that the SE exerts asymmetric loads that cause the OVs to flatten and shear caudally during the earliest stages of eye development and later to bend in the caudal and dorsal directions. These deformations cause the initially spherical OVs to become pear-shaped. Exposure to the myosin II inhibitor blebbistatin reduced these effects, suggesting that cytoskeletal contraction controls OV shape by regulating tension in the SE. To test the physical plausibility of these interpretations, we developed 2-D finite-element models for frontal and transverse cross-sections of the forebrain, including frictionless contact between the SE and OVs. With geometric data used to specify differential growth in the OVs, these models were used to simulate each experiment (control, SE removed, no contraction). For each case, the predicted shape of the OV agrees reasonably well with experiments. The results of this study indicate that differential growth in the OV and external pressure exerted by the SE are sufficient to cause the global changes in OV shape observed during the earliest stages of eye development.

The effects of misalignment during in vivo loading of bone: Techniques to detect the proximity of objects in three-dimensional models

Theories of mechanical adaptation of bone suggest that mechanical loading causes bone formation at discrete locations within bone microstructure experiencing the greatest mechanical stress/strain. Experimental testing of such theories requires in vivo loading experiments and high-resolution finite element models to determine the distribution of mechanical stresses. Finite element models of in vivo loading experiments typically assume idealized boundary conditions with applied load perfectly oriented on the bone, however small misalignments in load orientation during an in vivo experiment are unavoidable, and potentially confound the ability of finite element models to predict locations of bone formation at the scale of micrometers. Here we demonstrate two different three-dimensional spatial correlation methods to determine the effects of misalignment in load orientation on the locations of high mechanical stress/strain in the rodent tail loading model. We find that, in cancellous bone, the locations of tissue with high stress are maintained under reasonable misalignments in load orientation (p<0.01). In cortical bone, however, angular misalignments in the dorsal direction can alter the locations of high mechanical stress, but the locations of tissue with high stress are maintained under other misalignments (p<0.01). We conclude that, when using finite element models of the rodent tail loading model, small misalignments in loading orientation do not affect the predicted locations of high mechanical stress within cancellous bone.

Modifizierter Mini-Hardinge-Zugang zur Implantation von Hüftgelenksprothesen in Rückenlage

Total hip arthroplasty with a minimal-incision technique that can be performed in the widely used supine position. The accustomed and good overview of this position allows safe positioning of the implant and combines this with the advantage of a soft tissue preserving technique. All standard instruments and implants can be further applied. Primary and secondary coxarthrosis, femoral head necrosis. Revision surgery, severe anatomic deformity, implantation of hip resurfacing arthroplasty. Supine position. The skin incision runs from the innominate tubercle proximally and falls slightly in the dorsal direction (20-30°). Incision of the iliotibial tract and exposure of the vastogluteal muscle sling. Starting from the greater trochanter, the sinewy onset of the minimal and medium gluteal muscle is split with an arched-shaped incision, which also falls proximally in the dorsal direction. Exposition of the joint capsule, longitudinal incision and resection of the ventrolateral parts. Dislocation of the hip by a combined adduction and external rotation movement. Osteotomy of the femoral neck and resection of the femoral head are performed in a figure-of-four position without adduction. To prepare the acetabulum and to insert the cup, the leg is placed in neutral position with a slight flexion of 20° in the hip. Preparation of the femur and implantation of the stem is again performed in a figure-of-four position in adduction. Reduction of the hip and stepwise wound closure. Mobilization on postoperative day1. Starting with half weight bearing and after completed wound healing rapid increase to full weight bearing. Intensive physiotherapy and rehabilitation. Thrombosis prophylaxis according to guidelines. The mini-incision approach has successfully been used in our clinic for years. Between September 2004 and November 2005, the less-invasive technique was evaluated in a randomized controlled trial with 51patients (52hips). Compared to the standard approach a significantly shorter incision length (8.9 vs. 14.0cm) and a slightly lower blood loss (502 vs. 660ml) were observed for the modified mini-Hardinge. Moreover, the mini-incision group showed slightly better functional results in the early course. A higher rate of implant malpositioning or a higher peri- and postoperative complication rate was not observed.

Broad bandwidth acoustic backscattering from sandeel—measurements and finite element simulations

Abstract Acoustic backscattering measurements were made of individual sandeel (Ammodytes marinus L.) at frequencies from 100 to 280 kHz in a laboratory tank. Measurements were made versus incidence angle, −30° to 30° relative to both dorsal and lateral aspect directions, for dead whole sandeel and for excised backbones. Backscatter spectra from whole fish have deep minima at frequencies that vary with fish length and shift to lower frequencies at higher incidence angles. The backscatter spectra from dorsal and lateral aspects differ both in amplitude and in positions of the minima. The backscatter from the excised backbone increases almost linearly with frequency and, below about 150 kHz, contributes only a minor amount to the total sandeel backscatter. A finite element model of sandeel backscatter, developed and compared with the measurements, indicates that shear waves in the backbone contribute little to the overall backscatter from sandeel.

Inferior vermian hypoplasia – preconception, misconception

Inferior vermian hypoplasia – preconception, misconception

Developmental patterns of Ki-67, Oct-4 and α-tubulin proteins expression in the human spinal cord

The aim of this study was to analyze immunohistochemically the relationships between factors involved in processes of cell proliferation (Ki-67), differentiation (Oct-4) and primary cilia formation (α-tubulin) in the two parts of the developing human spinal cord (SC) of different origin in 11 human concepti (developmental weeks 5–10). Proliferation was highest in weeks 7–8 in the dorsal ventricular zones of the cranial (85.5%) and caudal (12.1%) SC. In the ventricular (VZ), intermediate (IZ) and marginal zones (MZ) of the cranial SC, α-tubulin and Oct-4 were moderately to strongly expressed. During weeks 5–6, moderate expression of α-tubulin and Oct-4 characterized the ventral part, with mild expression in the dorsal part of the caudal SC. In weeks 7–8, their expression increased in the VZ and IZ, and decreased in the MZ. In both parts of the SC Ki-67 and α-tubulin co-localized in the VZ. Oct-4 and Ki-67 co-localized only in the ependymal cells. In the cranial SC α-tubulin and Oct-4 co-localized (VZ and IZ), while the MZ expressed only α-tubulin. In the caudal SC, α-tubulin and Oct-4 co-localized in the VZ, while in the IZ some cells were only α-tubulin-positive. We suggest the importance of temporal–spatial expression of Ki-67 for the thickening of the cranial SC lateral wall. While in the cranial part of the SC, proliferation followed a ventral–dorsal direction, the caudal SC had a more irregular pattern. α-Tubulin was associated with cilia formation (ependymal cells) and axonic elongation of neuroblasts (MZ). Primary cilia signaling are important in control of SC proliferation and differentiation. Oct-4 expression in the SC coincided with presence of dividing neuroepithelial cells in the VZ and neuroblasts in the IZ, and could control the level of SC differentiation.

Guest Editorial

Guest Editorial

Movement within foot and ankle joint in children with spastic cerebral palsy: a 3-dimensional ultrasound analysis of medial gastrocnemius length with correction for effects of foot deformation

BackgroundIn spastic cerebral palsy (SCP), a limited range of motion of the foot (ROM), limits gait and other activities. Assessment of this limitation of ROM and knowledge of active mechanisms is of crucial importance for clinical treatment.MethodsFor a comparison between spastic cerebral palsy (SCP) children and typically developing children (TD), medial gastrocnemius muscle-tendon complex length was assessed using 3-D ultrasound imaging techniques, while exerting externally standardized moments via a hand-held dynamometer. Exemplary X-ray imaging of ankle and foot was used to confirm possible TD-SCP differences in foot deformation.ResultsSCP and TD did not differ in normalized level of excitation (EMG) of muscles studied. For given moments exerted in SCP, foot plate angles were all more towards plantar flexion than in TD. However, foot plate angle proved to be an invalid estimator of talocrural joint angle, since at equal foot plate angles, GM muscle-tendon complex was shorter in SCP (corresponding to an equivalent of 1 cm). A substantial difference remained even after normalizing for individual differences in tibia length. X-ray imaging of ankle and foot of one SCP child and two typically developed adults, confirmed that in SCP that of total footplate angle changes (0-4 Nm: 15°), the contribution of foot deformation to changes in foot plate angle (8) were as big as the contribution of dorsal flexion at the talocrural joint (7°). In typically developed individuals there were relatively smaller contributions (10 -11%) by foot deformation to changes in foot plate angle, indicating that the contribution of talocrural angle changes was most important.Using a new estimate for position at the talocrural joint (the difference between GM muscle–tendon complex length and tibia length, GM relative length) removed this effect, thus allowing more fair comparison of SCP and TD data. On the basis of analysis of foot plate angle and GM relative length as a function of externally applied moments, it is concluded that foot plate angle measurements underestimate angular changes at the talocrural joint when moving in dorsal flexion direction and overestimate them when moving in plantar flexion direction, with concomitant effects on triceps surae lengths.ConclusionsIn SCP children diagnosed with decreased dorsal ROM of the ankle joint, the commonly used measure (i.e. range of foot plate angle), is not a good estimate of rotation at the talocrural joint. since a sizable part of the movement of the foot (or foot plate) derives from internal deformation of the foot.

CT scan based determination of optimal bone corridor for atlantoaxial ventral screw fixation in miniature breed dogs

To describe the most reliable insertion angle, corridor length and width to place a ventral transarticular atlantoaxial screw in miniature breed dogs. Retrospective CT imaging study. Cervical CT scans of toy breed dogs (n = 21). Dogs were divided into 2 groups--group 1: no atlantoaxial abnormalities; group 2: atlantoaxial instability. Insertion angle in medial to lateral and ventral to dorsal direction was measured in group 1. Corridor length and width were measured in groups 1 and 2. Corridor width was measured at 3 points of the corridor. Each variable was measured 3 times and the mean used for statistical analysis. Mean ± SD optimal transarticular atlantoaxial insertion angle was determined to be 40 ± 1° in medial to lateral direction from the midline and 20 ± 1° in ventral to dorsal direction from the floor of the neural canal of C2. Mean corridor length was 7 mm (range, 4.5-8.0 mm). Significant correlation was found between corridor length, body weight, and age. Mean bone corridor width ranged from 3 to 5 mm. Statistically significant differences were found between individuals, gender and measured side. Optimal placement of a transarticular screw for atlantoaxial joint stabilization is very demanding because the screw path corridor is very narrow.

Median nerve deformation and displacement in the carpal tunnel during finger motion

The objective of this study was to evaluate the correlations between deformation and displacement of median nerve and flexor tendons during finger motion in the carpal tunnel for both carpal tunnel syndrome (CTS) patients and healthy controls. Sixty-two wrists of 31 asymptomatic volunteers and fifty-one wrists of 28 idiopathic CTS patients were evaluated by ultrasound. The displacement of the median nerve and the middle finger flexor digitorum superficialis (FDS) tendon, as well as area, perimeter, aspect ratio of a minimum enclosing rectangle, and circularity of the median nerve were measured in finger extension and flexion positions. Deformation indices were defined as the ratios of indices in finger extension and flexion positions. The correlations between displacement and deformation indices were evaluated. There were significant correlations between nerve palmar-dorsal displacement and deformation indices (p < 0.05). The aspect ratio deformation index showed the strongest correlation to palmar-dorsal displacement of the nerve (-0.572, p < 0.01). This study showed that there is a relationship between median nerve deformation indices and nerve palmar-dorsal displacement in the carpal tunnel. Since the highest correlations were between palmar-dorsal nerve displacement direction and aspect ratio deformation index, these parameters may be helpful to understand the pathophysiology of CTS.

CT Density Analysis of the Medial Cuneiform

A cannulated lag screw inserted through the medial cuneiform into the base of the second metatarsal is often utilized to reduce the diastasis and aid healing of Lisfranc injuries. Also procedures such as a midfoot or a Lapidus arthrodesis require adequate implant-bone purchase in the medial cuneiform. The medial cuneiform contains cancellous bone of varying density. Knowledge of density variation may be helpful for implant usage and manufacturing of area specific implants. In 60 randomly selected patients, mean computed tomography (CT) intensity in Hounsfield units was measured at 12 sampled locations within the medial cuneiform and served as a proxy for bone density. The patients' age, gender, and race were recorded. An analysis of variance (ANOVA) assessed the effect of age, gender, race, and sample site on bone density. Statistical testing assumed 95% level of confidence. ANOVA showed age, gender, and sample site had significant effects (P < .001) on bone density, though race had no significant effect (P = .28). The distal-dorsal-lateral (DDL) site was significantly denser than all other sites (P < .001) except the middle-dorsal-lateral (MDL) (P = .53). The proximal-plantar-lateral (PPL) site was significantly less dense than all other sites (P < .001) except the middle-plantar-lateral/medial and the proximal-plantar-medial sites (P < .14). A general trend of density increasing in the distal and dorsal directions was evident, and within the dorsal sites there was a trend of increasing density in the lateral direction. This is the first study to date to measure density of the medial cuneiform using living subjects. The sample size of 60 patients was also the largest of any study measuring density of this bone. We conclude that the densest area of the medial cuneiform is the most anterior, dorsal, and lateral portion. The findings of this study may indicate the most optimal area for implant purchase in the medial cuneiform when reducing the diastasis between the base of the second metatarsal and medial cuneiform and for stabilization of the medial column.

How much does the human medial gastrocnemius muscle contribute to ankle torques outside the sagittal plane?

Ankle movements in the frontal plane are less prominent though not less relevant than movements in the plantar or dorsal flexion direction. Walking on uneven terrains and standing on narrow stances are examples of circumstances likely imposing marked demands on the ankle medio-lateral stabilization. Following our previous evidence associating lateral bodily sways in quiet standing to activation of the medial gastrocnemius (MG) muscle, in this study we ask: how large is the MG contribution to ankle torque in the frontal plane? By arranging stimulation electrodes in a selective configuration, current pulses were applied primarily to the MG nerve branch of ten subjects. The contribution of populations of MG motor units of progressively smaller recruitment threshold to ankle torque was evaluated by increasing the stimulation amplitude by fixed amounts. From smallest intensities (12–32mA) leading to the firstly observable MG twitches in force-plate recordings, current pulses reached intensities (56–90mA) below which twitches in other muscles could not be observed from the skin. Key results showed a substantial MG torque contribution tending to rotate upward the foot medial aspect (ankle inversion). Nerve stimulation further revealed a linear relationship between the peak torque of ankle plantar flexion and inversion, across participants (Pearson R>.81, p<.01). Specifically, regardless of the current intensity applied, the peak torque of ankle inversion amounted to about 13% of plantar flexion peak torque. Physiologically, these results provide experimental evidence that MG activation may contribute to stabilize the body in the frontal plane, especially under situations of challenged stability.

Regional Lung Derecruitment and Inflammation during 16 Hours of Mechanical Ventilation in Supine Healthy Sheep

Lung derecruitment is common during general anesthesia. Mechanical ventilation with physiological tidal volumes could magnify derecruitment, and produce lung dysfunction and inflammation. The authors used positron emission tomography to study the process of derecruitment in normal lungs ventilated for 16 h and the corresponding changes in regional lung perfusion and inflammation. Six anesthetized supine sheep were ventilated with VT=8 ml/kg and positive end-expiratory pressure=0. Transmission scans were performed at 2-h intervals to assess regional aeration. Emission scans were acquired at baseline and after 16 h for the following tracers: (1) F-fluorodeoxyglucose to evaluate lung inflammation and (2) NN to calculate regional perfusion and shunt fraction. Gas fraction decreased from baseline to 16 h in dorsal (0.31±0.13 to 0.14±0.12, P<0.01), but not in ventral regions (0.61±0.03 to 0.63±0.07, P=nonsignificant), with time constants of 1.5-44.6 h. Although the vertical distribution of relative perfusion did not change from baseline to 16 h, shunt increased in dorsal regions (0.34±0.23 to 0.63±0.35, P<0.01). The average pulmonary net F-fluorodeoxyglucose uptake rate in six regions of interest along the ventral-dorsal direction increased from 3.4±1.4 at baseline to 4.1±1.5 10(-3)/min after 16 h (P<0.01), and the corresponding average regions of interest F-fluorodeoxyglucose phosphorylation rate increased from 2.0±0.2 to 2.5±0.2 10(-2)/min (P<0.01). When normal lungs are mechanically ventilated without positive end-expiratory pressure, loss of aeration occurs continuously for several hours and is preferentially localized to dorsal regions. Progressive lung derecruitment was associated with increased regional shunt, implying an insufficient hypoxic pulmonary vasoconstriction. The increased pulmonary net uptake and phosphorylation rates of F-fluorodeoxyglucose suggest an incipient inflammation in these initially normal lungs.

Using Tooth Rakes to Monitor Population and Sex Differences in Aggressive Behaviour in Bottlenose Dolphins (Tursiops truncatus)

This study investigated intraspecific tooth rake scarring, an established indicator of received aggression by conspecifics, on bottlenose dolphins (Tursiops truncatus) to gain knowledge of aggressive interactions. The differences in tooth rake scarring between male and female dolphins on the east coast of Scotland were examined, and overall levels of scarring were compared with dolphins on the west coast of Scotland (Sound of Barra and Hebrides). Photographs were examined for evidence of tooth rake scarring using four different methods. East coast males displayed significantly higher scarring percentages (i.e., body area covered by tooth rake scarring), numbers of dorsal fin rake directions (i.e., whether tooth rake scars were vertical, horizontal, diagonal, or curved), and nick percentage (i.e., amount of the dorsal fin missing due to nicks) than females. Differences also existed between the three areas, with bottlenose dolphins around the Sound of Barra showing significantly lower levels of dorsal fin rake directions than those on the east coast or Hebrides. Observed sex differences are likely the result of intrasexual conflict between males over access to females. However, other factors such as sex- or age-specific behaviours or sexual coercion of females may also be involved. Such information could potentially be used to differentiate between the sexes. The differences in dorsal fin scarring between these populations suggests differences in aggressive interactions, possibly indicating differences in social structure. The lower scarring levels seen in the Sound of Barra group may support the suggestion that bottlenose dolphins on the west coast belong to two communities. However, this variability in conspecific aggression may also be the result of different social behaviours, age or sex ratios, habitat, resources, or individual behavioural differences.