Antigenic properties of peptidic mimics for epitopes of the lipopolysaccharide from Brucella

The lipopolysaccharide (LPS) is up to now the only identified major virulence determinant of Brucella. This bacterium is responsible for brucellosis in animals and for Malta fever in humans. Several monoclonal antibodies (mAbs) directed against various LPS epitopes have been characterized. Two mAbs, named A15-6B3 and B66-2C8, directed against distinct LPS epitopes have been used to select peptides from 11 phage display libraries. The sequences of the selected peptides contain an overrepresentation of either proline or tryptophan residues when selected with either A15-6B3 or B66-2C8 mAbs, respectively. For the best binding peptides, competition with LPS for the binding to the mAb is detected, which suggests that the peptides bind to the paratope of the mAb. The phages selected from the libraries were used to immunise mice, and a weak antibody response directed against LPS has been observed. These data suggest that a subset of the selected peptides are mimotopes of the LPS epitopes.

Electrical stimulation of motor cortex for pain control: a combined PET-scan and electrophysiological study

Although electrical stimulation of the precentral gyrus (MCS) is emerging as a promising technique for pain control, its mechanisms of action remain obscure, and its application largely empirical. Using positron emission tomography (PET) we studied regional changes in cerebral flood flow (rCBF) in 10 patients undergoing motor cortex stimulation for pain control, seven of whom also underwent somatosensory evoked potentials and nociceptive spinal reflex recordings. The most significant MCS-related increase in rCBF concerned the ventral-lateral thalamus, probably reflecting cortico-thalamic connections from motor areas. CBF increases were also observed in medial thalamus, anterior cingulate/orbitofrontal cortex, anterior insula and upper brainstem; conversely, no significant CBF changes appeared in motor areas beneath the stimulating electrode. Somatosensory evoked potentials from SI remained stable during MCS, and no rCBF changes were observed in somatosensory cortex during the procedure. Our results suggest that descending axons, rather than apical dendrites, are primarily activated by MCS, and highlight the thalamus as the key structure mediating functional MCS effects. A model of MCS action is proposed, whereby activation of thalamic nuclei directly connected with motor and premotor cortices would entail a cascade of synaptic events in pain-related structures receiving afferents from these nuclei, including the medial thalamus, anterior cingulate and upper brainstem. MCS could influence the affective-emotional component of chronic pain by way of cingulate/orbitofrontal activation, and lead to descending inhibition of pain impulses by activation of the brainstem, also suggested by attenuation of spinal flexion reflexes. In contrast, the hypothesis of somatosensory cortex activation by MCS could not be confirmed by our results.

[Chronic hydrocephalus in an adult due to congenital membranous occlusion of the apertura mediana ventriculi quartii (foramen of Magendie). Report of two cases and review of the literature]

Congenital membranous obstruction of the apertura mediana ventriculi quartii (foramen of Magendie) is a rare entity, as only 8 adult cases are mentioned in all medical literature. We report here the cases of 2 patients (35 and 68 year-old) with chronic hydrocephalus due to congenital membranous obstruction of the foramen of Magendie. Both these two patients presented with headaches, nausea, and impairment of gait and memory. CT and MRI examination showed a communicating hydrocephalus, with particular enlargement of the fourth ventricle. Both patients were operated on for microsurgical exploration of the outlet of the fourth ventricle, which demonstrated membranous obstruction of the foramen of Magendie. Microsurgical perforation of the foramen of Magendie was performed, and a ventriculo-cisternal shunt was left in place. The two patients were cured, with a follow-up of 7 years in one case, and 5 years in the other case. Despite its rare occurrence, congenital imperforation or membranous obstruction of the foramen of Magendie must be considered as a possible etiology of chronic hydrocephalus in adult, especially in case of non proportioned enlargement of the fourth ventricle, associated to signs of increased intra-cranial pressure. According to us, the best surgical procedure consists in a microsurgical exploration of the foramen of Magendie associated to a ventriculo-cisternal shunting (from the fourth ventricle to the cisterna magna). Such a procedure can be considered as curative, and has more advantages than a simple ventriculo-peritoneal shunting.

A new type of microelectrode for obtaining unitary recordings in the human spinal cord

OBJECT

In this paper the authors report on the conception and adjustment of a microelectrode used to obtain unitary recordings in the human spinal cord.

METHOD

To overcome the difficulties related to intraoperative pulsations of the spinal cord, the authors opted to use a floating microelectrode. Because the recordings are obtained most often from spontaneous activities, it is difficult, with a single microelectrode, to separate spikes from electrical artifacts that are related to the switching of devices. Consequently, the authors designed a dual microelectrode made of two tungsten-in-glass-attached microelectrodes separated by 300 microm. Because the two electrodes cannot obtain recordings in the same neuron, it is possible to distinguish unambiguously spikes (recorded on one tip) from electrical artifacts (recorded simultaneously on the two tips). The dual microelectrode is 2 cm long, with a 20-microm tip length, and 800 to 1200-Ohms impedance. This microelectrode can be implanted "free hand," in the dorsal horn, by using a microsurgical forceps under a surgical microscope. The data analysis is performed off-line with spike sorter hardware. In the dorsal horns in 17 patients who were selected to undergo a dorsal root entry zone (DREZ) rhizotomy to treat various pathological conditions, unitary recordings were obtained using this double microelectrode. The authors recorded 57 neurons in good conditions of stability and isolation.

CONCLUSIONS

The microelectrode described in this paper was successfully used to obtain recordings in neurons in more than 85% of the patients. This simplified, floating double microelectrode can therefore be considered for use in microsurgical DREZ rhizotomy to obtain unitary recordings in the human spinal dorsal horn.

Regression of vasomotor disorders under intrathecal baclofen in a case of spastic paraplegia

Continuous intrathecal baclofen infusion via a subcutaneously implanted programmable pump has been used in the treatment of severe spasticity. Improvement classically concerns the neurological (hypertonia, spasms, hyperreflexia), urological (bladder function) and other clinically relevant outcomes, such as functional status of daily living. This short note reports on another effect of intrathecal baclofen on vasomotor disorders and cyanosis in the lower limbs, described in a patient with spastic paraplegia.

Hyperalgesia with reduced laser evoked potentials in neuropathic pain

Nociceptive evoked potentials to laser stimuli (LEPs) are able to detect lesions of pain and temperature pathways at peripheral, spinal and supraspinal levels. It is commonly accepted that LEP attenuation correlates with the loss of pain and temperature sensations, while pathological heat-pain hypersensitivity has been associated with increased LEP amplitude. Here we present two patients in whom increased pain sensation (hyperalgesia) to laser stimuli was, on the contrary, associated to delayed, desynchronized and attenuated LEPs. Both patients experienced increased unpleasantness and affective reactions to laser, associated to poor ability to localize the stimulus. In both cases the results may be explained by an overactivation of the 'medial pain system', in one patient due to deafferentation of cortical sensory areas by a capsular lesion, and in the other to imbalance between A-delta and C fiber excitation due to peripheral nerve injury. Our results suggest that LEPs, as currently recorded, reflect the activity of a 'lateral' pain system subserved by rapidly conducting fibers. They may therefore, assess the sensory and cognitive dimensions of pain, but may not index adequately the affective-emotional aspects of pain sensation conveyed by the 'medial' pain system. The dissociation between pain sensation and cortical EPs deserve to be added to the current semiology of LEPs, as the presence of abnormal pain to laser on the background of reduced LEPs substantiates the neuropathic nature of the pain.

Production and characterisation of monoclonal antibodies specific for bovine interleukin-4

Genetic immunisation is a simple method for producing polyclonal antibodies in mice. By this method, we produced antibodies against bovine interleukin-4 (BoIL-4). After a final injection with a recombinant BoIL-4 protein, nine stable hybridoma cell lines were established which secreted monoclonal antibodies (MAbs) against this cytokine. Specific binding of each of the MAbs to recombinant BoIL-4 produced by Escherichia coli, baculovirus, and Trypanosoma brucei was demonstrated in an indirect ELISA and/or in Western blotting. These MAbs recognise the same antigenic region localised in the first 47 amino acids of the mature protein. None of them was able to neutralise the biological activity of the BoIL-4 under the conditions tested but one allowed the detection of BoIL-4 by flow cytometry.

A stereoelectroencephalographic (SEEG) study of light-induced mesiotemporal epileptic seizures

PURPOSE

This study explored the mechanism of light-induced complex partial seizures by using ictal intracerebral recordings in a patient with refractory epilepsy of the right temporal lobe.

METHODS

Presurgical evaluation of this patient was realized by means of video-EEG recordings, WADA test, magnetic resonance imaging (MRI), F18-deoxyglucose and C11-flumazenil positron emission tomography (PET) interictal neuroimaging data, and stereoelectroencephalographic (SEEG) ictal recordings.

RESULTS

SEEG investigations demonstrated the right mesiotemporal origin of all the patient's seizures. This result was confirmed by a successful right temporal lobectomy. Moreover, SEEG recordings revealed a frequent interictal spiking activity in the right occipital visual cortex that was undetectable on scalp recordings. However, the occipital cortex was not involved at the onset of mesiotemporal ictal discharges and was not hyperresponsive to focal electrical stimulation.

CONCLUSIONS

This study shows that, in spite of interictal occipital spiking, the photosensitivity of mesiotemporal seizures can be observed in both the absence of occipital cortex involvement during ictal discharges and demonstrable hyperexcitability of the occipital cortex to light or direct electrical stimulation.

[Microsurgical drezotomy for the treatment of spasticity of the lower limbs]

Ablative functional neurosurgery can be useful in some selected patients for the treatment of harmful spasticity in the lower limbs. Microsurgical drezotomy was introduced in 1972, on the basis of anatomical studies of the human dorsal root entry zone (DREZ) showing a topographical segregation of the afferent fibers according to their size and thus functional destinations. It consists of a 3 mm deep microsurgical lesion directed at a 45 degree angle in the postero-lateral sulcus, penetrating the DREZ in its ventro-lateral aspect, at the level of all the rootlets considered as involved in spasticity (and pain). It destroys mainly the lateral (nociceptive) and central (myotatic) afferent fibers as well as the facilitatory medial part of the Lissauer tract, whilst sparing most of the medial (lemniscal) fibers and the inhibitor lateral part of the Lissauer tract. We report a series of 121 bedridden patients suffering from harmful spasticity in one (15) or both (106) lower limbs and treated with microsurgical drezotomy. Surgery was decided on because of abnormal postures in flexion in two-thirds of the patients and in hyperextension in one-third, additional pain in 75 of them, and hyperactive bladder in 38 cases. The post-operative results were evaluated after a mean follow-up time of 5 years and 6 months. Both spasticity and spasms were significantly decreased or suppressed respectively in 78% and 88% of the patients. When present, pain was relieved without abolition of sensation in 82%. These benefits resulted in either disappearance or marked reduction of the abnormal postures and articular limitation in 90% of the patients. When present preoperatively, urinary leakage disappeared in 85% of the cases. Mild to severe complications occurred in 32 patients and precipitated or were responsible for death in 6 cases (5%). This is explained by the fact that most of the patients, especially those affected by multiple sclerosis, were in very precarious general and neurological conditions. Microsurgical drezotomy has however enabled a large majority of these severely disabled patients to sit and lie comfortably, and allowed them to reach a significantly improved quality of life.

[The development of gait in the hemiplegic patient after selective tibial neurotomy]

BACKGROUND AND PURPOSE

Spastic Foot may constitute a severe functional deficit leading to instability in stance and inappropriate prepositioning of the foot for its initial contact with the ground. The purpose of the study was to analyze the results of selective tibial neurotomy on gait.

METHOD

After clinical examination of nine hemiplegic patients, gait was recorded before surgery and six months after. Three-dimensional bilateral kinematic data were obtained with a motion measurement system (VICON), and muscular electrical activity on affected side was detected with surface electrodes. The patient walked barefoot, with his free velocity, on a ten meter track in the lab. An analogic visual scale was used by the patient to evaluate gait discomfort.

RESULTS

After neurotomy, triceps surae spasticity decreased and passive motion of ankle increased. Gait comfort was better, claw toes and sore skin disappeared. Kinematics data were modified by neurotomy in all patients. On the affected side, ankle dorsiflexion improved during stance for five patients and residual motricity improved during the swing phase for two patients. Stance knee hyperextension was corrected in the five patients. EMG data: Selective tibial neurotomy caused disappearance of triceps surae peak activity at the beginning of the stance phase and at the end of swing phase. The time activity of the other muscles did not change.

CONCLUSION

Selective tibial neurotomy can cure foot deformity and modify ankle motion during gait. It corrects knee hyperextension during stance phase.

The unreamed locked intramedullary tibial nail: a follow-up study in 51 patients

The authors reviewed 51 patients with a fracture of the tibia primarily treated with an unreamed intramedullary nail. There were 29 open and 22 closed fractures. All fractures healed within one year of the trauma. There were no deep infections. The most frequently observed complication was failure of interlocking screws (20%), but this complication had a negligible influence on bone healing. Re-nailing with a reamed nail was necessary in 18%. According to the criteria of Klemm and Börner an excellent result was obtained in 55% and a good result in 44%. The authors recommend unreamed nailing in fractures with soft tissue injuries; they recommend to dynamize the implant after six weeks in transverse and short oblique fractures and to replace the unreamed nail by a reamed one after three months in case of delayed union.

Gastrocolic vein. Definition and report of two cases of avulsion

The gastrocolic v. or Henle's gastrocolic trunk was described in 1868 [9]. We suggest defining this vein as the confluence of the right gastroepiploic and right upper colic vv. We report two original cases of avulsion of the gastrocolic v. occurring during a blunt abdominal trauma. The aim of this paper is a description, based on the literature, of the anatomy of the gastrocolic v. in order to precise the lesional mechanism. The gastrocolic v. is present in 70% of individuals. It is short (less than 25 mm) but of major calibre (3 to 10 mm). The gastrocolic v. is situated close beneath the root of the transverse mesocolon, and travels along the anterior surface of the head of the pancreas. Anatomic variations are detailed and a meta-analysis of interpretable studies was made. Both the supra- and infra-mesocolic surgical approaches are described. The radiologic and surgical importance of the gastrocolic v. is discussed. The lesional mechanism in both our cases of injury of the gastrocolic v. is explained.

Selective dorsal rhizotomy in children with cerebral palsy. Results in 18 cases at one year postoperatively

OBJECTIVE

Effects of selective dorsal rhizotomy (SDR) were studied in children with spastic cerebral palsy in orthopaedic and functional fields.

METHODS

In a prospective study, we compared the same population before SDR and 1 year after SDR. This population included children with spastic cerebral palsy, when spasticity was responsible for a halt in the motor skill acquisitions or for orthopaedic complications. All the children had intensive physiotherapy for 6 months postoperatively. We observed spasticity by a 4-point scale, isolation of movement by a 3-point scale, and orthopaedic status by the measure of range of motion, hip migration on the radiography, and function by Gross Motor Function Measure (GMFM) and Abbott scale. All the assessments were done by the same physiotherapist. We compared the results with a Wilcoxon statistic test.

RESULTS

18 quadriplegic children had spastic cerebral palsy; their mean age was 9 years (5.5-16.5 years). We observed a decrease in spasticity in all the muscular groups; increase in range of motion only on abduction and extension of the hips; no evolution of hip migration; an increase of 3.2% in the total GMFM score; 1 child was classified IV before SDR and V after SDR on the Abbott scale; 3 children had planned orthopaedic surgery in the year after SDR; 16 children and their families were highly satisfied with the result of the surgery.

CONCLUSIONS

The decrease in spasticity does not entail prevention of orthopaedic problems in children with quadriplegic spastic cerebral palsy. However, we observed an improvement in qualitative function that is outside the scope of current assessment scales.

Somatosensory evoked potentials following functional posterior rhizotomy in spastic children

Ten children with cerebral palsy and severe lower limb spasticity were treated by functional posterior rhizotomy (FPR). Somatosensory evoked potential recordings were performed preoperatively, intraoperatively (directly on the surface of the spinal cord) and 6 months after surgery, to evaluate the effects of FPR on lower limb somatosensory function. Before surgery, 7/10 patients showed abnormal cortical responses after tibial stimulation. In all patients, intraoperative recordings showed a reduction in the amplitude of segmental responses (N22) (50 +/- 25% of reference value) after the section of a mean 50% of L2-S2 dorsal rootlets. The modifications of segmental responses (N22) were maintained 6 months after surgery, whereas reduction of cortical responses (P39) did not reach the significance level when compared with preoperative recordings.

Positron emission tomography during motor cortex stimulation for pain control

We studied regional changes in cerebral flood flow (rCBF) in 9 patients undergoing motor cortex stimulation (MCS) for pain control. Significant increase in rCBF was observed in the lateral thalamus ipsilateral to MCS probably reflecting corticothalamic connections from motor/premotor areas. Subsignificant increases were observed in the anterior cingulate, left insula and upper brainstem. Mean rCBF in the anterior cingulate increased during MCS in patients with good analgesic efficacy, while it decreased in those with poor clinical outcome; conversely, thalamic rCBF increased in the two groups, albeit to a greater extent in patients with good clinical results. Our results support a model of MCS action whereby activation of thalamic nuclei directly connected with motor and premotor cortices would entail a cascade of synaptic events in other pain-related structures, including the anterior cingulate and the periaqueductal gray. MCS could influence the affective-emotional component of chronic pain by way of cingulate activation, and lead to descending inhibition of pain impulses by activation of the brainstem. Such effects may be obtained only if thalamic activation reaches a 'threshold' level, below which the analgesic cascade would not be successfully triggered.

Microsurgical DREZotomy for pain due to brachial plexus avulsion: long-term results in a series of 37 patients

The authors analyzed the postoperative and long-term results of the microsurgical DREZotomy procedure performed in 37 patients suffering from chronic pain due to brachial plexus avulsion. The evaluation was based on clinical parameters. The immediate results consisted of good pain relief (pain relief > 75%) in 79% of the patients. A long-lasting good pain relief has been achieved in 66.5% of the patients with a mean follow-up of 60 months (range 12-120). The morbidity rate was 5%.

Expression of plasminogen activator inhibitors type-1 and type-2 in the mouse lung after administration of crystalline silica

Altered expression of plasminogen activator inhibitors (PAIs) is of potential relevance to the process of lung fibrosis. To clarify the involvement of PAIs in interstitial lung diseases, we examined whether alterations in PAI-1 and PAI-2 were induced in response to a single intratracheal administration of a fibrosing dose of crystalline silica in mice (5 mg x animal(-1)). The time course of changes in PAI activity and PAI-1 protein were characterized in bronchoalveolar lavage fluid (BALF) and changes in PAI-1 and PAI-2 messenger ribonucleic acid (mRNAs) were monitored by reverse transcriptase polymerase chain reaction (RT-PCR) in BALF cells and lung tissue up to the fibrotic stage of the disease. Substantial levels of PAI activity were found in BALF of control animals, whereas no PAI-1 protein was detected. In response to silica treatment, we observed an acute increase of PAI activity and PAI-1 protein levels in BALF (day 1), associated with an induction of PAI-1 and PAI-2 mRNA levels in lung tissue. In alveolar macrophages, silica treatment induced a persistent upregulation of PAI-2 mRNA only. One month after silica treatment, PAI activity was undetectable in BALF while substantial PAI activity was still present in controls. At the same time point, sustained upregulation of PAI-1 and PAI- 2 mRNAs was, however, noted in lung tissue of animals treated with silica. These findings support the possible implication of PAIs in the remodelling process induced by silica in the lung.

[Oto-neuro-surgical approach and accessibility to the cochlear nuclei. Significance in auditory brain stem implant]

The auditory brainstem implant (ABI) is now used to stimulate the cochlear nucleus to obtain auditory perception in patients with type 2 neurofibromatosis. Only electrical stimulation of the cochlear nucleus complex, in the lateral recess of the fourth ventricle, can achieve auditory rehabilitation of these profound bilateral retrocochlear deafness. With 20 standard translabyrinthine approaches, our personal anatomical study propose to describe surgical landmarks of the cochlear nuclear complex and surgical accessibility of the lateral recess of the fourth ventricle. The root of vestibulocochlear nerve, the glossopharyngeal nerve and the choroid plexus of the fourth ventricle might have surgical significance because of their reliability.

Biological monitoring of workers exposed to low levels of 2-butoxyethanol

OBJECTIVES

(1) To assess the value of urinary butoxyacetic acid (BAA) measurement for the monitoring of workers exposed to low concentration of 2-butoxyethanol (BE); (2) to evaluate the in vivo effect of low occupational BE exposure on the erythrocyte lineage; and (3) to test the possible influence of genetic polymorphism for cytochrome P450 2E1 (CYP 2E1) on urinary BAA excretion rate.

METHODS

Thirty-one male workers exposed to BE in a beverage package production plant were examined according to their external (BE) and internal (BAA) solvent exposure. The effect of this exposure on erythrocyte lineage [red blood cell numeration (RBC), hemoglobin (Hb), hematocrit (Htc), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), haptoglobin (Hp), reticulocyte numeration (Ret) and osmotic resistance (OR)], hepatic [aspartate aminotransferase (GOT), alanine aminotransferase (GPT)] and renal [plasmatic creatinine, urinary retinol binding protein (RBP)] parameters was also investigated. DNA purified from whole blood was used for CYP 2E1 genotyping.

RESULTS

Average airborne concentration of BE was 2.91 mg/m3 (0.59 ppm) with a standard deviation of 1.30 mg/m3 (0.27 ppm). There was a relatively good correlation between external and internal exposure estimated by measuring BAA in post-shift urine samples (average 10.4 mg/g creatinine; r = 0.55; P = 0.0012). Compared with a matched control group (n = 21) exposed workers had a statistically significant decrease (3.3%; P = 0.03) in Hct while MCHC was increased (2.1%; P = 0.02). No significant difference was observed either in other erythroid parameters or in hepatic and renal biomarkers. One exposed individual exhibited a mutant allele with increased cytochrome P450 oxidative activity which coincided with a very low urinary BAA excretion.

CONCLUSIONS

Single determination of BAA in post-shift urine samples can be used to assess exposure to low levels of BE. A slight but significant effect on erythroid parameters suggesting membrane damage was observed in exposed workers. The influence of the genetic polymorphism for CYP 2E1 deserves further investigation for the interpretation of urinary BAA measurements.

[Assessment of procarbazine, vincristine and lomustine association (PCV protocol) in oligodendroglioma and mixed glioma]

Effective chemotherapy using PCV (procarbazine, lomustine and vincristine) has been documented in anaplastic oligodendrogliomas and oligoastrocytomas. A pilot study using PCV was conducted for relapsing patients with anaplastic oligodendrogliomas and oligoastrocytomas. Preliminary results are reported. Fourteen patients were enrolled. All received at least two courses of PCV and were evaluable for response. Eleven patients (78%) responded to chemotherapy with complete responses in 2 patients. Response was more obvious regarding contrast enhanced areas than volumes changes (11 responses versus 7). A story of seizure was the main clinical prognostic factor for response. All toxicities were manageable and no treatment related death occurred. Chemotherapy is an effective treatment in aggressive oligodendrogliomas. Further studies must assess the role of chemotherapy in the multidisciplinary management of oligodendroglioma.

Clinical use of polysynaptic flexion reflexes in the management of spasticity with intrathecal baclofen

The aim of this study was to evaluate the clinical usefulness of lower limb flexion reflexes (FR) in the assessment of spinal excitability responsible for spontaneous or induced spasms. FR were recorded on the short head of biceps femoris, after electrical stimulation of the ipsilateral sural nerve at the ankle, in 17 spastic patients selected for chronic intrathecal administration of baclofen. The results obtained before and after treatment were compared with clinical scores commonly used to assess spasticity (Ashworth and spasm scores). Before intrathecal baclofen 15/17 patients (88%) had pathologically enhanced flexor reflexes in the lower limbs, which were associated to clinical spasms. Reflex enhancement was accompanied in 47% of cases by abnormal decrease of reflex threshold. No significant correlation appeared between the magnitude or threshold of FR in control conditions and either the hypertonia (Ashworth scale) or the number of clinical spasms per unit of time. Intrathecal baclofen attenuated flexor reflex amplitude and increased reflex threshold in all patients. Our results suggest that FR investigate the intrinsic features of the spasms (threshold, intensity and duration) not assessed clinically, and that therefore the information gathered from FR recordings is not redundant with, and adds significantly to, that obtained by clinical scales. In our experience, FR recordings appeared to be a useful tool for quantifying the benefit of antispastic treatment and might be used as an ancillary indicator to determine the minimal effective dose of intrathecal baclofen.

Use of fluoxetine to treat dominance aggression in dogs

OBJECTIVE

To evaluate fluoxetine for the treatment of owner-directed dominance aggression in dogs.

DESIGN

Prospective study.

ANIMALS

9 dogs of various breeds, ages, and either sex determined to have owner-directed dominance aggression.

PROCEDURE

Placebo and fluoxetine (1 mg/kg of body weight) were compared for the treatment of owner-directed dominance aggression in a single-blind crossover study. Owners were instructed to record aggressive and nonaggressive responses of their dogs daily on a canine-overt aggression chart for the 5-week duration of the study. Total aggression scores (linear and geometric) were calculated for each week of the study. The frequency of individual responses was also analyzed independently.

RESULTS

Fluoxetine resulted in a significant (P = 0.01) reduction in owner-directed dominance aggression after 3 weeks of treatment. No particular aggressive response accounted for the overall reduction in aggression.

CLINICAL IMPLICATIONS

Fluoxetine may be useful in the management of dominance aggression in dogs.