Botulinum toxin in clinical practice

Botox(®) to reduce drooling in a paediatric population with neurological impairments: a Phase I study

BACKGROUND

The treatment of drooling in a paediatric population with neurological impairments is clinically challenging. Surgery is considered invasive, while behaviour modification techniques, correction of situational factors and oral-motor therapy do not always produce sustained improvement. In recent years the use of Botox® to decrease drooling has been investigated.

AIMS

To review the clinical data from a Drooling Treatment Project for children with neurological impairments and to establish the validity of the drooling severity and frequency rating scales, establishing Phase I-level information about the therapeutic use of submandibular salivary gland injections of Botox® in various contexts.

METHOD & PROCEDURES

A retrospective, explanatory design was used to review the data. Nine children, seven with cerebral palsy and two with operculum syndrome, ranging in age from 5 to 17 years (mean = 9;3 years) were included. Drooling was assessed by qualified speech-language therapists using drooling rating scales, in five different situations and at different time points pre- and post-Botox® injection up to 6 months. Quantitative and qualitative analyses were computed. Parents'/primary caregivers' perceptions of drooling and treatment with Botox® were also considered using an interview form and a quality of life questionnaire.

OUTCOMES & RESULTS

Statistically significant reductions in drooling with large effect sizes were obtained in the communicating and general appearance situations. There was a difference in the pattern of response between the children with cerebral palsy and those with operculum syndrome. Discrepancies between the parents and the speech-language therapists regarding the context of drooling reduction were found. Most parents/primary caregivers felt their children's lives and their own had improved following the Botox® injection and would repeat the treatment. The drooling rating scales were a valid method to assess drooling in a clinical situation.

CONCLUSIONS & IMPLICATIONS

In the clinical setting of the Drooling Treatment Project, the results indicated that the context in which drooling occurs is an important factor and suggested the value of considering the situational context when making drooling judgments. Further, there was a difference in the pattern of response between the children with cerebral palsy and those with operculum syndrome, suggesting that aetiology may be involved in the response to Botox®.

Embryonic stem cell-derived motoneurons provide a highly sensitive cell culture model for botulinum neurotoxin studies, with implications for high-throughput drug discovery

Botulinum neurotoxins (BoNTs) inhibit cholinergic synaptic transmission by specifically cleaving proteins that are crucial for neurotransmitter exocytosis. Due to the lethality of these toxins, there are elevated concerns regarding their possible use as bioterrorism agents. Moreover, their widespread use for cosmetic purposes, and as medical treatments, has increased the potential risk of accidental overdosing and environmental exposure. Hence, there is an urgent need to develop novel modalities to counter BoNT intoxication. Mammalian motoneurons are the main target of BoNTs; however, due to the difficulty and poor efficiency of the procedures required to isolate the cells, they are not suitable for high-throughput drug screening assays. Here, we explored the suitability of embryonic stem (ES) cell-derived motoneurons as a renewable, reproducible, and physiologically relevant system for BoNT studies. We found that the sensitivity of ES-derived motoneurons to BoNT/A intoxication is comparable to that of primary mouse spinal motoneurons. Additionally, we demonstrated that several BoNT/A inhibitors protected SNAP-25, the BoNT/A substrate, in the ES-derived motoneuron system. Furthermore, this system is compatible with immunofluorescence-based high-throughput studies. These data suggest that ES-derived motoneurons provide a highly sensitive system that is amenable to large-scale screenings to rapidly identify and evaluate the biological efficacies of novel therapeutics.

Efficacy and safety of incobotulinumtoxinA (NT 201, Xeomin) in the treatment of blepharospasm-a randomized trial

IncobotulinumtoxinA (NT 201, Xeomin) is a highly purified botulinum neurotoxin type A formulation, free from complexing proteins. A randomized, placebo-controlled, double-blind trial of efficacy and safety compared incobotulinumtoxinA (up to 50 U per eye) to placebo administered in a single treatment session to patients with blepharospasm. All patients had documented satisfactory response to 2 previous treatments with botulinum neurotoxin type A other than incobotulinumtoxinA and had Jankovic Rating Scale severity subscores ≥ 2. Patients (n = 109) were randomized in a 2:1 ratio to incobotulinumtoxinA or placebo and followed up to 20 weeks; 94% completed the study. A significant difference was observed in the primary efficacy variable (change in Jankovic Rating Scale severity subscore rated by an independent rater 6 weeks following treatment), favoring incobotulinumtoxinA by 1.0 point (95% CI [0.5-1.4]; P < .001). Functional impairment, as measured by the Blepharospasm Disability Index, improved by 0.5 points (95% CI [0.2-0.7]; P = .002) compared with placebo. There was a strong correlation between the 2 scale scores. In addition, all secondary outcome measures favored incobotulinumtoxinA. Patients rated the mean therapeutic effect of incobotulinumtoxinA significantly better than placebo (P < .001). Adverse events were reported in 70.3% of incobotulinumtoxinA patients and 58.8% of placebo patients. Eyelid ptosis (18.9% vs 5.9%), dry eye (18.9% vs 11.8%), and dry mouth (14.9% vs 2.9%) occurred most frequently. Tolerability was rated good/very good by 91.9% of incobotulinumtoxinA versus in 85.2% of placebo patients. In conclusion, incobotulinumtoxinA was well tolerated and was associated with statistically significant and clinically relevant reductions in blepharospasm severity and functional impairment.

Regions of botulinum neurotoxin A light chain recognized by human anti-toxin antibodies from cervical dystonia patients immunoresistant to toxin treatment. The antigenic structure of the active toxin recognized by human antibodies

This work was aimed at determining the BoNT/A L-chain antigenic regions recognized by blocking antibodies in human antisera from cervical dystonia patients who had become immunoresistant to BoNT/A treatment. Antisera from 28 immunoresistant patients were analyzed for binding to each of 32 overlapping synthetic peptides that spanned the entire L-chain. A mixture of the antisera showed that antibodies bound to three peptides, L11 (residues 141-159), L14 (183-201) and L18 (239-257). When mapped separately, the antibodies were bound only by a limited set of peptides. No peptide bound antibodies from all the patients and amounts of antibodies bound to a given peptide varied with the patient. Peptides L11, L14 and L18 were recognized predominantly. A small but significant number of patients had antibodies to peptides L27 (365-383) and L29 (379-397). Other peptides were recognized at very low and perhaps insignificant antibody levels by a minority (15% or less) of patients or had no detectable antibody with any of the sera. In the 3-dimensional structure, antibody-binding regions L11, L14 and L18 of the L-chain occupy surface areas and did not correlate with electrostatic potential, hydrophilicity/hydrophobicity, or temperature factor. These three antigenic regions reside in close proximity to the belt of the heavy chain. The regions L11 and L18 are accessible in both the free light chain and the holotoxin forms, while L14 appears to be less accessible in the holotoxin. Antibodies against these regions could prevent delivery of the L-chain into the neurons by inhibition of the translocation.

Targeted secretion inhibitors-innovative protein therapeutics

Botulinum neurotoxins are highly effective therapeutic products. Their therapeutic success results from highly specific and potent inhibition of neurotransmitter release with a duration of action measured in months. These same properties, however, make the botulinum neurotoxins the most potent acute lethal toxins known. Their toxicity and restricted target cell activity severely limits their clinical utility. Understanding the structure-function relationship of the neurotoxins has enabled the development of recombinant proteins selectively incorporating specific aspects of their pharmacology. The resulting proteins are not neurotoxins, but a new class of biopharmaceuticals, Targeted Secretion Inhibitors (TSI), suitable for the treatment of a wide range of diseases where secretion plays a major role. TSI proteins inhibit secretion for a prolonged period following a single application, making them particularly suited to the treatment of chronic diseases. A TSI for the treatment of chronic pain is in clinical development.

Comparison of effects of botulinum toxin subtype A1 and A2 using twitch tension assay and rat grip strength test

Botulinum toxin type A is used as a therapeutic agent for some spastic neurological disorders. Type A organisms have been classified into four subtypes (A1 to A4) based on the amino acid sequence variability of the produced neurotoxin. At present, commercially available preparations of the toxin belong to subtype A1. To date, no study has compared the characteristics of the biological activity of toxins from different subtypes. We compared the efficacy of A1 toxin (LL toxin or neurotoxin: NTX) with that of A2 toxin (NTX) employing the twitch tension assay using the mouse phrenic nerve hemidiaphragm and grip strength test in rats. The inhibitory effects on neuromuscular transmission of A2NTX at pH 7.4 and pH 6.8 were 1.95 and 3.73 times more potent than those of A1LL, respectively. The 50% effective doses for the administered limb, the dose which caused a 50% reduction in grip strength, i.e. ED(50), of A1LL, A1NTX, and A2NTX were calculated as 0.087, 0.060, and 0.040 U/head, respectively. These doses for the contralateral limb, i.e. TD(50), of A1LL, A1NTX, and A2NTX were calculated as 6.35, 7.54, and 15.62 U/head, respectively. In addition, the time required for A2NTX-injected rats to recover the grip strength of the contralateral limb was 17 days, while that for rats injected with A1LL was 35 days. The results indicated that A2NTX is a more potent neuromuscular blocker than A1 toxins, and suggested that A2NTX will provide a preferentical therapeutic agent for neurological disorders.

A transverse and longitudinal MR imaging voxel-based morphometry study in patients with primary cervical dystonia

BACKGROUND AND PURPOSE

Findings of standard MR imaging examinations are usually normal in primary CD. These findings are now increasingly challenged by studies using advanced neuroimaging techniques detecting abnormalities in brain areas that may be functionally involved in the pathophysiology of CD. Our purpose was to evaluate GM volumes in patients with CD at baseline and 5 years later.

MATERIALS AND METHODS

We enrolled 19 patients (F/M = 15:4, mean age = 53.2 + 11.2 years), 12 of whom were studied at baseline and again approximately 5 years later. Twenty-eight healthy volunteers acted as controls (F/M = 17:11, mean age = 47.5 + 15.6 years). The subjects were imaged with a 1.5T scanner by using a 3D T1-weighted sequence on 150 contiguous axial 1-mm-thick sections to apply VBM.

RESULTS

At entry, VBM analysis disclosed significantly lower GM volumes in the left caudate head and putamen and in the premotor and primary sensorimotor cortices bilaterally in patients than in controls. No correlation was found between decreased GM volumes and patient age, severity of dystonia, or disease duration. At the 5-year follow-up, GM volumes in the left primary sensorimotor cortex in patients had decreased significantly from baseline.

CONCLUSIONS

The findings obtained at entry and after a 5-year follow-up consistently showed decreased caudate, putamen, and sensorimotor cortex GM volumes in patients with CD, and they probably play a pathophysiologic role in CD.

SNARE tagging allows stepwise assembly of a multimodular medicinal toxin

Generation of supramolecular architectures through controlled linking of suitable building blocks can offer new perspectives to medicine and applied technologies. Current linking strategies often rely on chemical methods that have limitations and cannot take full advantage of the recombinant technologies. Here we used SNARE proteins, namely, syntaxin, SNAP25, and synaptobrevin, which form stable tetrahelical complexes that drive fusion of intracellular membranes, as versatile tags for irreversible linking of recombinant and synthetic functional units. We show that SNARE tagging allows stepwise production of a functional modular medicinal toxin, namely, botulinum neurotoxin type A, commonly known as BOTOX. This toxin consists of three structurally independent units: Receptor-binding domain (Rbd), Translocation domain (Td), and the Light chain (Lc), the last being a proteolytic enzyme. Fusing the receptor-binding domain with synaptobrevin SNARE motif allowed delivery of the active part of botulinum neurotoxin (Lc-Td), tagged with SNAP25, into neurons. Our data show that SNARE-tagged toxin was able to cleave its intraneuronal molecular target and to inhibit release of neurotransmitters. The reassembled toxin provides a safer alternative to existing botulinum neurotoxin and may offer wider use of this popular research and medical tool. Finally, SNARE tagging allowed the Rbd portion of the toxin to be used to deliver quantum dots and other fluorescent markers into neurons, showing versatility of this unique tagging and self-assembly technique. Together, these results demonstrate that the SNARE tetrahelical coiled-coil allows controlled linking of various building blocks into multifunctional assemblies.

The use of botulinum toxin A in children with cerebral palsy, with a focus on the lower limb

PURPOSE

The purpose of this review is to clarify the role of botulinum toxin serotype A (BTX-A) in the treatment of children with cerebral palsy (CP), with a special focus on the lower limb.

BACKGROUND

The treatment of spasticity is central in the clinical management of children with CP. BTX-A blocks the release of acetylcholine at the motor end plate, causing a temporary muscular denervation and, in an indirect way, a reduced spasticity. Children with increased tone develop secondary problems over time, such as muscle contractures and bony deformities, which impair their function and which need orthopaedic surgery. However in these younger children, delaying surgery is crucial because the results of early surgical interventions are less predictable and have a higher risk of failure and relapse. As BTX-A treatment reduces tone in a selective way, it allows a better motor control and muscle balance across joints, resulting in an improved range of motion and potential to strengthen antagonist muscles, when started at a young age. The effects are even more obvious when the correct BTX-A application is combined with other conservative therapies, such as physiotherapy, orthotic management and casts. There is now clear evidence that the consequences of persistent increased muscle tone can be limited by applying an integrated multi-level BTX-A treatment approach. Nevertheless, important challenges such as patient selection, defining appropriate individual goals, timing, dosing and dilution, accuracy of injection technique and how to measure outcomes will be questioned. Therefore, "reflection is more important than injection" remains an actual statement.

Hemifacial spasm non-motor and motor-related symptoms and their response to botulinum toxin therapy

Hemifacial spasm (HFS) is a chronic movement disorder which presents as clonic and/or tonic facial muscle contractions frequently accompanied by many other sensory (visual or auditory disturbances, pain), motor (facial weakness, trismus, bruxism, dysarthria) and/or autonomic (lacrimation, salivation) symptoms. The aim of the study was to assess the occurrence of HFS non-motor and motor-related symptoms and their responsiveness to botulinum toxin type A (BTX-A) therapy. 56 HFS patients were included in the open-label design study. Patients were examined three times: before BTX-A injection, and 2 and 12 weeks later. The occurrence of non-motor and motor-related symptoms was assessed by a special questionnaire, and the severity of HFS was rated by the Clinical Global Impression-Severity scale (CGI-S) and depression symptoms by the Beck Depression Inventory (BDI). Over 81% of the patients before BTX-A therapy reported HFS non-motor and motor-related symptoms. Almost 50% of the patients reported more than three symptoms. The most frequent symptoms were: tearing (44.5%), eye irritation (39.3%), facial paraesthesia (26.8%) and hearing of a "clicking" sound (25.0%). 2 weeks after BTX-A injection 75% of the patients did not report any symptoms and 20% reported only one or two. 3 months later the number of symptoms had increased again, with 57% of patients reporting at least one. The number of HFS non-motor and other symptoms did not correlate with the patients' age, disease duration and the presence of neuro-vascular conflict, but were positively correlated with the CGI-S and BDI scores. This study showed that muscle contractions in HFS patients are commonly accompanied by non-motor and other motor-related symptoms and most of them are reduced following BTX-A treatment.

Aggregatibacter actinomycetemcomitans leukotoxin: from threat to therapy

Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium that colonizes the human oral cavity and is the causative agent for localized aggressive periodontitis (LAP), an aggressive form of periodontal disease that occurs in adolescents. A. actinomycetemcomitans secretes a protein toxin, leukotoxin (LtxA), which helps the bacterium evade the host immune response during infection. LtxA is a membrane-active toxin that specifically targets white blood cells (WBCs). In this review, we discuss recent developments in this field, including the identification and characterization of genes and proteins involved in secretion, regulation of LtxA, biosynthesis, newly described activities of LtxA, and how LtxA may be used as a therapy for the treatment of diseases.

Clostridial toxins

Clostridia produce the highest number of toxins of any type of bacteria and are involved in severe diseases in humans and other animals. Most of the clostridial toxins are pore-forming toxins responsible for gangrenes and gastrointestinal diseases. Among them, perfringolysin has been extensively studied and it is the paradigm of the cholesterol-dependent cytolysins, whereas Clostridium perfringens epsilon-toxin and Clostridium septicum alpha-toxin, which are related to aerolysin, are the prototypes of clostridial toxins that form small pores. Other toxins active on the cell surface possess an enzymatic activity, such as phospholipase C and collagenase, and are involved in the degradation of specific cell-membrane or extracellular-matrix components. Three groups of clostridial toxins have the ability to enter cells: large clostridial glucosylating toxins, binary toxins and neurotoxins. The binary and large clostridial glucosylating toxins alter the actin cytoskeleton by enzymatically modifying the actin monomers and the regulatory proteins from the Rho family, respectively. Clostridial neurotoxins proteolyse key components of neuroexocytosis. Botulinum neurotoxins inhibit neurotransmission at neuromuscular junctions, whereas tetanus toxin targets the inhibitory interneurons of the CNS. The high potency of clostridial toxins results from their specific targets, which have an essential cellular function, and from the type of modification that they induce. In addition, clostridial toxins are useful pharmacological and biological tools.

Quantitative determination of biological activity of botulinum toxins utilizing compound muscle action potentials (CMAP), and comparison of neuromuscular transmission blockage and muscle flaccidity among toxins

The biological activity of various types of botulinum toxin has been evaluated using the mouse intraperitoneal LD(50) test (ip LD(50)). This method requires a large number of mice to precisely determine toxin activity, and so has posed a problem with regard to animal welfare. We have used a direct measure of neuromuscular transmission, the compound muscle action potential (CMAP), to evaluate the effect of different types of botulinum neurotoxin (NTX), and we compared the effects of these toxins to evaluate muscle relaxation by employing the digit abduction scoring (DAS) assay. This method can be used to measure a broad range of toxin activities the day after administration. Types A, C, C/D, and E NTX reduced the CMAP amplitude one day after administration at below 1 ip LD(50), an effect that cannot be detected using the mouse ip LD(50) assay. The method is useful not only for measuring toxin activity, but also for evaluating the characteristics of different types of NTX. The rat CMAP test is straightforward, highly reproducible, and can directly determine the efficacy of toxin preparations through their inhibition of neuromuscular transmission. Thus, this method may be suitable for pharmacology studies and the quality control of toxin preparations.

Anti-leukemia activity of a bacterial toxin with natural specificity for LFA-1 on white blood cells

The oral bacterium, Aggregatibacter actinomycetemcomitans, produces a leukotoxin (LtxA) that is specific for white blood cells (WBCs) from humans and Old World primates by interacting with lymphocyte function antigen-1 (LFA-1) on susceptible cells. To determine if LtxA could be used as a therapeutic agent for the treatment of WBC diseases, we tested the in vitro and in vivo anti-leukemia activity of the toxin. LtxA kills human malignant WBC lines and primary leukemia cells from acute myeloid leukemia patients, but healthy peripheral blood mononuclear cells (PBMCs) are relatively resistant to LtxA-mediated cytotoxicity. Levels of LFA-1 on cell lines correlated with killing by LtxA and the toxin preferentially killed cells expressing the activated form of LFA-1. In a SCID mouse model for human leukemia, LtxA had potent therapeutic value resulting in long-term survival in LtxA-treated mice. Intravenous infusion of LtxA into a rhesus macaque resulted in a drop in WBC counts at early times post-infusion; however, red blood cells, platelets, hemoglobin and blood chemistry values remained unaffected. Thus, LtxA may be an effective and safe novel therapeutic agent for the treatment of hematologic malignancies.

Measurement of botulinum types A, B and E neurotoxicity using the phrenic nerve-hemidiaphragm: improved precision with in-bred mice

Botulinum neurotoxins induce a prolonged muscle paralysis by specifically blocking the release of neuronal transmitters from peripheral nerve junctions. The current method for assessing the potency of botulinum toxin and antitoxins is the mouse LD50 assay. The mouse phrenic nerve-diaphragm assay is an in vitro assay that closely mimics in vivo respiratory paralysis. In this study, we have further improved the assay by using gelatin as a non-frothing alternative to albumin and investigated the effects of botulinum toxin serotypes A, B and E on phrenic nerve-hemidiaphragms from out-bred MF1 and in-bred Balb/c mice. Improved reproducibility was found with in-bred mice. Balb/c mice were also found to be much less sensitive to type B toxin perhaps indicating differences in the expression of receptor components. Hemidiaphragm preparations from Balb/c mice were approximately 7 times more sensitive to type A toxin and 7-12 times more sensitive to type E toxin relative to type B toxin. These findings indicate that when fully optimised the mouse nerve-diaphragm preparation can provide a functional in vitro model for accurate and reproducible assessment of toxin activity.

Palmar hyperhidrosis: long-term follow-up of nine children and adolescents treated with botulinum toxin type A

Primary palmar hyperhidrosis in children and adolescents may be severe enough to affect school and physical activities, causing emotional problems, stress in the patient's life, and a compromised quality of life. Nine patients with palmar hyperhidrosis underwent treatment with botulinum A. Before the session, and in the 1-, 3-, 6-, 9-, and 12-month post-session follow-ups, the patients were administered the Minor test, gravimetry, the Scales of Frequency and Severity, and the Questionnaire of Quality of Life. The mean age was 11 years, with seven girls and two boys. Each patient was administered at least one treatment of botulinum toxin in the palm of the hands (75-150 U for palm), with the mean number of sessions 2.2 (range: 1-4). All sessions in the patients resulted in drying of the hands, with a mean duration of effect of 7 months. Botulinum toxin A controls excessive sweat in the palms of children and adolescents who have primary palmar hyperhidrosis, with an improvement in the quality of life. The therapy is safe and effective in this pediatric group and can be considered before surgical interventions.

Neuritogenic actions of botulinum neurotoxin A on cultured motor neurons

Botulinum neurotoxins (BoNTs) are extremely potent neuromuscular poisons that act through soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein cleavage to inhibit neurotransmitter release. The ability of BoNT serotype A (BoNT/A) to eliminate localized transmitter release at extremely low doses is well characterized. In the current study, we investigated the less understood characteristic of BoNT/A to induce nerve outgrowth, sometimes referred to as sprouting. This phenomenon is generally considered a secondary response to the paralytic actions of BoNT/A, and other potential factors that may initiate this sprouting have not been investigated. Alternatively, we hypothesized that BoNT/A induces sprouting through presynaptic receptor activation that is independent of its known intracellular actions on the soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) synaptosomal associated protein of 25 kDa (SNAP-25). To test this, the effects of BoNT/A application on neurite outgrowth were examined using primary cultures enriched with motor neurons isolated from embryonic mouse spinal cord. In this system, BoNT/A potently stimulated neuritogenesis at concentrations as low as 0.01 nM. The neuritogenic effects of BoNT/A exposure were concentration dependent and antagonized by Triticum vulgaris lectin, a known competitive antagonist of BoNT. Similar results were observed with the isolated BoNT/A binding domain, revealing that neuritogenesis could be initiated solely by the binding actions of BoNT/A. In addition, the presence or absence of SNAP-25 cleavage by BoNT/A was not a determinant factor in BoNT/A-induced neuritogenesis. Collectively, these results suggest that binding of BoNT/A to the motor neuronal membrane activates neuritogenesis through as yet undetermined intracellular pathway(s), independent of its known action on vesicular release.

Treatment of dystonia

Dystonia varies in severity from simple focal dystonia, such as writer's cramp to life-threatening status dystonicus. Even though the pathophysiology is still elusive, symptomatic treatments may provide marked relief. Botulinum toxin is considered the treatment of choice for most focal and segmental dystonias. Deep brain stimulation of the basal ganglia, particularly the globus pallidus internum, is emerging as an important treatment for refractory, generalized, and segmental forms of dystonia. Gene therapy is also being explored as a possible treatment of inherited dystonias. This article reviews the therapeutic options available for the various types of dystonia.

Botulinum toxin prevents radiotherapy-induced salivary gland damage

Radiotherapy of head and neck malignancies results in severe damage to salivary glands. Irradiation-induced sialadenitis with xerostomia leads to a significant deterioration of the quality of life which lasts life-long. Here we show in a preliminary study that intraglandular application of botulinum toxin performed prior to radiation reduces significantly the radiation induced toxicity of the glandular tissue in rats.

A reappraisal of the central effects of botulinum neurotoxin type A: by what mechanism?

Botulinum neurotoxin A (BoNT/A) is a metalloprotease that enters peripheral motor nerve terminals and blocks the release of acetylcholine via the specific cleavage of the synaptosomal-associated protein of 25-kDa. Localized injections of BoNT/A are widely employed in clinical neurology to treat several human diseases characterized by muscle hyperactivity. It is generally assumed that the effects of BoNT/A remain localized to the injection site. However, several neurophysiological studies have provided evidence for central effects of BoNT/A, raising the issue of how these actions arise. Here we review these data and discuss the possibility that retrograde axonal transport of catalytically active BoNT/A may explain at least some of its effects at the level of central circuits.

Treatment of phantom limb pain with botulinum toxin type A

INTRODUCTION

Phantom limb pain and sensations are common in amputees. The pathophysiology remains unclear and the treatment difficult and often unsuccessful. Opioids are frequently used when non-narcotics have failed, but are not effective in many cases. We report on three phantom and stump pain patients, refractive to previous treatments, who were successfully treated with botulinum toxin A (BoNT-A).

METHODS

Three patients who had previously undergone amputation of their leg due to accident (N = 2) or injury by a landmine (N = 1) were treated with BoNT-A (Dysport). We injected a total dose of up to 500 units (U) BoNT-A under EMG-control. Global clinical improvement was based on a 0-3 scale (0 = no effect; 3 = marked improvement) and on a questionnaire rating pain intensity (based on the visual analog scale), intake of pain medication and phantom limb sensations.

RESULTS

All three patients evaluated the clinical global improvement with 3 (marked improvement). The pain intensity and pain medication was reduced significantly in all three cases. No side effects were reported. The duration of response lasted up to 11 weeks.

DISCUSSION

These three successfully treated phantom and stump pain patients show that therapy with BoNT-A may be worth studying as an effective and safe treatment option for this kind of pain.

Asymmetrical focal neurological deficits in dogs and cats with naturally occurring tick paralysis (Ixodes holocyclus): 27 cases (1999-2006)

OBJECTIVE

To describe basic epidemiological features, clinical characteristics and outcomes of asymmetrical focal neurological deficits identified in dogs and cats with naturally occurring tick paralysis (Ixodes holocyclus).

DESIGN

A retrospective study.

PROCEDURE

Computer records were reviewed for all dogs and cats treated for tick paralysis between July 1999 and June 2006 at a suburban veterinary hospital in Newcastle, New South Wales.

RESULTS

Neurological deficits were identified in 17/197 dogs and 10/89 cats and included unilateral facial paralysis (14 dogs; 2 cats), anisocoria (4 dogs; 7 cats), unilateral loss of the cutaneous trunci reflex (1 dog; 1 cat) and Horner's syndrome in 2 cats with anisocoria. Occurrence of deficits was not linked to season, severity of tick paralysis, breed, age, sex or body weight. With facial paralysis and anisocoria, the site of tick attachment was invariably on the head or neck and always ipsilateral to the facial paralysis. By contrast, with anisocoria alone, no consistent relationship was noted between any one pupillary dimension and the side of tick attachment. With cutaneous trunci deficits the site of tick attachment was the ipsilateral caudal axilla. Compared with recovery times from generalised signs of tick paralysis, those for facial paralysis were significantly longer (days to weeks; P < 0.001), those for anisocoria showed no significant difference (P = 0.25) and those for cutaneous trunci deficits lagged by 6 and 7 days.

CONCLUSIONS

Asymmetrical focal neurological deficits are a consistent finding in a proportion of dogs and cats with naturally occurring tick paralysis due to I. holocylcus.

Long-term treatment with botulinum toxin type A in cervical dystonia has low immunogenicity by mouse protection assay

To evaluate the immunogenicity of botulinum toxin type A (BoNTA; BOTOX) in cervical dystonia (CD). Subjects diagnosed with CD for > or =1 year and previously naïve to BoNTs were treated with BoNTA in a prospective, open-label, multicenter study. Serum samples were analyzed for BoNTA neutralizing antibodies using the Mouse Protection Assay (MPA). Clinical resistance was assessed with a test injection of 20 U BoNTA placed unilaterally into the frontalis (Frontalis Antibody Test; FTAT) or corrugator muscle (Unilateral Brow Injection; UBI). Efficacy was assessed and adverse events were recorded. Of 326 subjects enrolled, 251 (77%) completed the study. Subjects received a median of 9 BoNTA treatments (mean dose per session ranged from 148.4 to 213.0 U over a mean of 2.5 years [range: 3.2 months-4.2 years]). Only 4 of 326 subjects (1.2%) tested positive for antibodies in the MPA; three of these subjects stopped responding clinically to BoNTA (of whom one also showed clinical resistance in the FTAT) and one continued to respond. Consistent improvements in the signs/symptoms of CD were noted. The most frequent treatment-related adverse events were mild to moderate weakness, dysphagia, neck pain, and injection-site pain. The current formulation of BoNTA rarely causes neutralizing antibody formation in CD subjects treated < or =4 years.

Biological activity of two botulinum toxin type A complexes (Dysport and Botox) in volunteers: a double-blind, randomized, dose-ranging study

Despite extensive clinical experience and published data regarding botulinum toxin, questions remain about the clinical substitution of one botulinum toxin formulation for another. In the case of Dysport and Botox, dose-equivalence ratios ranging from 1:1 to 6:1 (Dysport:Botox) have been advocated. This dose-ranging, electroneurographic study investigated the dose equivalence, diffusion characteristics (spread) and safety of these two type-A toxins in 79 volunteers. Dysport and Botox caused significant and similar reductions in compound muscle action potential (CMAP) amplitude in the target muscle (extensor digitorum brevis, EDB) 2 weeks after injection, with effects persisting to the 12-week timepoint. For both products, the reduction in amplitude was increased with increasing doses and with increasing concentration. The effects of toxin on neighbouring muscles were much smaller and of a shorter duration than those on the target muscle, implying a modest spread of toxin. Unlike the target muscle, the effects were greater with the higher volume, suggesting this volume led to greater diffusion from the EDB. No adverse events were reported. Statistical modelling with CMAP amplitude data from the target muscle gave a bioequivalence of 1.57 units of Dysport:1 unit of Botox (95 % CI: 0.77-3.20 units). The data indicate that a dose-equivalence ratio of 3:1 was within the statistical error limits, but ratios over 3:1 are too high.

Lack of anti-inflammatory effect of botulinum toxin type A in experimental models of inflammation

Botulinum toxin type A (BTX-A) has a long-lasting antinociceptive activity and less clear effect on inflammation. It was proposed that these two effects share the same mechanism--the inhibition of neurotransmitter exocytosis from peripheral nerve endings. However, till now possible anti-inflammatory action of BTX-A did not evoke much attention. In the present paper, we investigate possible anti-inflammatory action of the toxin in carrageenan and capsaicin models of inflammation in rats. BTX-A (5 and 10 U/kg) was injected into the plantar surface of the rat right hind-paw pad 5 days before the injection of the carrageenan (1%) or capsaicin (0.1%) at the same site. Carrageenan-induced paw oedema and capsaicin-induced protein extravasation were measured. Control, inflamed and BTX-A pretreated inflamed paws were photographed and histopathological analysis (haematoxylin & eosin) was performed. Pretreatment with BTX-A had no effect on the size of carrageenan-induced paw oedema, measured as paw volume and weight or capsaicin-induced plasma extravasations, measured by Evans blue as a marker of protein leakage. Neither macroscopic nor microscopic analysis showed a significant difference between BTX-A pretreated and control inflamed tissue. Results show dissociation between the effect of BTX-A on pain and inflammation thus questioning the validity of the suggested assumption about the common peripheral mechanism of action.

The Intercostal NMJ Assay: a new alternative to the conventional LD50 assay for the determination of the therapeutic potency of botulinum toxin preparations

Therapeutic botulinum neurotoxin type A preparations have found an increasing number of clinical uses for a large variety of neuromuscular disorders and dermatological conditions. The accurate determination of potency in the clinical application of botulinum toxins is critical to ensuring clinical efficacy and safety, and is currently achieved by using a lethal dose (LD50) assay in mice. Ethical concerns and operational constraints associated with this assay have prompted the development of alternative assay systems that could potentially lead to its replacement. As one such alternative, we describe the development and evaluation of a novel ex vivo assay (the Intercostal Neuromuscular Junction [NMJ] Assay), which uses substantially fewer animals and addresses ethical concerns associated with the LD50 assay. The assay records the decay of force from electrically-stimulated muscle tissue sections in response to the toxin, and thus combines the important mechanisms of receptor binding, translocation, and the enzymatic action of the toxin molecule. Toxin application leads to a time-related and dose-related reduction in contractile force. A regression model describing the relationship between the applied dose and force decay was determined statistically, and was successfully tested as able to correctly predict the potency of an unknown sample. The tissue sections used were found to be highly reproducible, as determined through the innervation pattern and the localisation of NMJs in situ. Furthermore, the efficacy of the assay protocol to successfully deliver the test sample to the cellular target sites, was critically assessed by using molecular tracer molecules.

Transient tardive dystonia: overview and case presentation

Dystonia is a syndrome of involuntary, repetitive (or sustained) muscle contractions of opposing muscles, which may result in torsions and abnormal postures. Tardive dystonia is a form of the disorder that starts after longer term use of dopamine antagonists. It occurs in approximately 3% of patients receiving ongoing antipsychotic treatment and is often difficult to reverse. Dystonia can also be induced by compounds other than antipsychotics, such as antidepressants, levodopa, carbamazepine, dextroamphetamine, and diphenylhydantoin. In these cases, it is transient, generally disappearing after the dose is reduced or the causative drug is stopped. Dystonia induced by injury can also be transient. We report a case of transient oromandibular dystonia following a dental filling in a woman receiving quetiapine, a second-generation antipsychotic. The timing, localization, and transience of the dystonia suggested that the dental procedure may have played a triggering role. The dystonia symptoms responded within 8 weeks to benztropine and a dose reduction of quetiapine, and they did not return when benztropine was discontinued. This case benefited from prompt attention and has led to practical recommendations for psychiatric clinicians.

Successful treatment of tardive lingual dystonia with botulinum toxin: case report and review of the literature

Tardive dyskinesia (TD) is a dreaded side effect of antipsychotic medication. Recommended treatments for TD may provide reliable improvement but can be, in turn, associated with additional adverse reactions. Recently, several reports have suggested that botulinum toxin A (BTX-A) injection in affected muscles may significantly improve TD. Here, we report a case of severe tongue protrusion dystonia secondary to an antipsychotic medication in a young man. Several approaches including clozapine, amisulpride, aripiprazole, ziprasidone, tiapride and clonazepam failed to improve the symptoms. Injection of 50 U of BTX-A (Dysport, Ipsen, Ettlingen, Germany) into each genioglossal muscle dramatically improved tongue protrusion within few days with a sustained effect. If reasonable precautions are taken, the application seems to be well tolerated with only minor side effects. A review of the literature that is part of this article adverts BTX-A injection as a potential beneficial approach of various kinds of TD.

Attomolar detection of botulinum toxin type A in complex biological matrices

BACKGROUND

A highly sensitive, rapid and cost efficient method that can detect active botulinum neurotoxin (BoNT) in complex biological samples such as foods or serum is desired in order to 1) counter the potential bioterrorist threat 2) enhance food safety 3) enable future pharmacokinetic studies in medical applications that utilize BoNTs.

METHODOLOGY/PRINCIPAL FINDINGS

Here we describe a botulinum neurotoxin serotype A assay with a large immuno-sorbent surface area (BoNT/A ALISSA) that captures a low number of toxin molecules and measures their intrinsic metalloprotease activity with a fluorogenic substrate. In direct comparison with the "gold standard" mouse bioassay, the ALISSA is four to five orders of magnitudes more sensitive and considerably faster. Our method reaches attomolar sensitivities in serum, milk, carrot juice, and in the diluent fluid used in the mouse assay. ALISSA has high specificity for the targeted type A toxin when tested against alternative proteases including other BoNT serotypes and trypsin, and it detects the holotoxin as well as the multi-protein complex form of BoNT/A. The assay was optimized for temperature, substrate concentration, size and volume proportions of the immuno-sorbent matrix, enrichment and reaction times. Finally, a kinetic model is presented that is consistent with the observed improvement in sensitivity.

CONCLUSIONS/SIGNIFICANCE

The sensitivity, specificity, speed and simplicity of the BoNT ALISSA should make this method attractive for diagnostic, biodefense and pharmacological applications.