Internalization and Mechanism of Action of Clostridial Toxins in Neurons

Botulinum Toxin Treatment of Psoriasis-A Comprehensive Review

A literature search on the subject of botulinum toxin treatment in psoriasis found 15 relevant articles, 11 on human subjects and 4 on animal studies. Of the human data, eight were clinical trials and three were single case reports. Seven out of eight clinical trials, all open-label, reported improvement in psoriasis following intradermal or subcutaneous botulinum toxin injections. One double-blind, placebo-controlled study, which used a smaller dose than the open-label studies, did not note a healing effect. Animal studies have shown that injection of botulinum toxins in the skin heals psoriatic skin lesions and can reduce the level of interleukins (ILs) and cytokines as well as inflammatory cells in psoriatic plaques. There is a need for controlled, blinded studies conducted in larger numbers of patients with doses that have shown promise in open-label studies.

Local Tetanus Begins with a Neuromuscular Junction Paralysis around the Site of Tetanus Neurotoxin Release due to Cleavage of the Vesicle-Associated Membrane Protein

Local tetanus develops when limited amounts of tetanus neurotoxin (TeNT) are released by Clostridium tetani generated from spores inside a necrotic wound. Within days, a spastic paralysis restricted to the muscles of the affected anatomical area develops. This paralysis follows the retrograde transport of TeNT inside the axons of motoneurons and its uptake by inhibitory interneurons with cleavage of a vesicle-associated membrane protein required for neurotransmitter release. Consequently, incontrollable excitation of motoneurons causes contractures of innervated muscles and leads to local spastic paralysis. Here, the initial events occurring close to the site of TeNT release were investigated in a mouse model of local tetanus. A peripheral flaccid paralysis was found to occur, before or concurrent to the spastic paralysis. At variance from the confined TeNT proteolytic activity taking place within motor neuron terminals, central protein cleavage was detected within inhibitory interneurons controlling motor neuron efferents innervating muscle groups distant from the site of TeNT release. These results indicate peripheral activity of TeNT in tetanus and explains why the spastic paralysis observed in local tetanus, although confined to single limbs, generally affects multiple muscles. The initial TeNT neuroparalytic activity can be detected by measuring the compound muscle action potential, providing a very early diagnosis and therapy, thus preventing the ensuing life-threatening generalized tetanus.

Toxicology and pharmacology of botulinum and tetanus neurotoxins: an update

Tetanus and botulinum neurotoxins cause the neuroparalytic syndromes of tetanus and botulism, respectively, by delivering inside different types of neurons, metalloproteases specifically cleaving the SNARE proteins that are essential for the release of neurotransmitters. Research on their mechanism of action is intensively carried out in order to devise improved therapies based on antibodies and chemical drugs. Recently, major results have been obtained with human monoclonal antibodies and with single chain antibodies that have allowed one to neutralize the metalloprotease activity of botulinum neurotoxin type A1 inside neurons. In addition, a method has been devised to induce a rapid molecular evolution of the metalloprotease domain of botulinum neurotoxin followed by selection driven to re-target the metalloprotease activity versus novel targets with respect to the SNARE proteins. At the same time, an intense and wide spectrum clinical research on novel therapeutics based on botulinum neurotoxins is carried out, which are also reviewed here.

Quantitation of Acetyl Hexapeptide-8 in Cosmetics by Hydrophilic Interaction Liquid Chromatography Coupled to Photo Diode Array Detection

Bioactive peptides are gaining more and more popularity in the research and development of cosmetic products with anti-aging effect. Acetyl hexapeptide-8 is a hydrophilic peptide incorporated in cosmetics to reduce the under-eye wrinkles and the forehead furrows. Hydrophilic interaction liquid chromatography (HILIC) is the separation technique of choice for analyzing peptides. In this work, a rapid HILIC method coupled to photodiode array detection operated at 214 nm was developed, validated and used to determine acetyl-hexapeptide-8 in cosmetics. Chromatography was performed on a Xbridge® HILIC BEH analytical column using as mobile phase a 40 mM ammonium formate water solution (pH 6.5)-acetonitrile mixture 30:70, v/v at flow rate 0.25 mL min−1. The assay was linear over the concentration range 20 to 30 μg mL−1 for the cosmetic formulations and 0.004 to 0.007% (w/w) for the cosmetic cream. The limits of quantitation for acetyl hexapeptide-8 were 1.5 μg mL−1 and 0.002% (w/w) for the assay of cosmetic formulations and cosmetic creams, respectively. The method was applied to the analysis of cosmetic formulations and anti-wrinkle cosmetic creams.

Electrical Stimulation of Injected Muscles to Boost Botulinum Toxin Effect on Spasticity: Rationale, Systematic Review and State of the Art

Botulinum toxin type A (BoNT-A) represents a first-line treatment for spasticity, a common disabling consequence of many neurological diseases. Electrical stimulation of motor nerve endings has been reported to boost the effect of BoNT-A. To date, a wide range of stimulation protocols has been proposed in the literature. We conducted a systematic review of current literature on the protocols of electrical stimulation to boost the effect of BoNT-A injection in patients with spasticity. A systematic search using the MeSH terms “electric stimulation”, “muscle spasticity” and “botulinum toxins” and strings “electric stimulation [mh] OR electrical stimulation AND muscle spasticity [mh] OR spasticity AND botulinum toxins [mh] OR botulinum toxin type A” was conducted on PubMed, Scopus, PEDro and Cochrane library electronic databases. Full-text articles written in English and published from database inception to March 2021 were included. Data on patient characteristics, electrical stimulation protocols and outcome measures were collected. This systematic review provides a complete overview of current literature on the role of electrical stimulation to boost the effect of BoNT-A injection for spasticity, together with a critical discussion on its rationale based on the neurobiology of BoNT-A uptake.

Time-course transcriptomics reveals that amino acids catabolism plays a key role in toxinogenesis and morphology in Clostridium tetani

Tetanus is a fatal disease caused by Clostridium tetani infections. To prevent infections, a toxoid vaccine, developed almost a century ago, is routinely used in humans and animals. The vaccine is listed in the World Health Organisation list of Essential Medicines and can be produced and administered very cheaply in the developing world for less than one US Dollar per dose. Recent developments in both analytical tools and frameworks for systems biology provide industry with an opportunity to gain a deeper understanding of the parameters that determine C. tetani virulence and physiological behaviour in bioreactors. Here, we compared a traditional fermentation process with a fermentation medium supplemented with five heavily consumed amino acids. The experiment demonstrated that amino acid catabolism plays a key role in the virulence of C. tetani. The addition of the five amino acids favoured growth, decreased toxin production and changed C. tetani morphology. Using time-course transcriptomics, we created a “fermentation map”, which shows that the tetanus toxin transcriptional regulator BotR, P21 and the tetanus toxin gene was downregulated. Moreover, this in-depth analysis revealed potential genes that might be involved in C. tetani virulence regulation. We observed differential expression of genes related to cell separation, surface/cell adhesion, pyrimidine biosynthesis and salvage, flagellar motility, and prophage genes. Overall, the fermentation map shows that, mediated by free amino acid concentrations, virulence in C. tetani is regulated at the transcriptional level and affects a plethora of metabolic functions.

Inactivated tetanus as an immunological smokescreen: A major step towards harnessing tetanus-based therapeutics

BACKGROUND AND PURPOSE

Tetanus neurotoxin has many potential therapeutic applications, due to its ability to increase localised muscle tone when injected directly into a muscle. It is a closely related molecule to botulinum neurotoxin (most commonly known as Botox), which has been widely used to release muscle tension for therapeutic and cosmetic applications. However, tetanus toxin has been relegated to the "maybe pile" for protein therapeutics - as most of the population is vaccinated, leading to highly effective antibody-mediated protection against the toxin. The potential for tetanus-based therapeutics remains substantial if the problem of pre-existing immunity can be resolved.

EXPERIMENTAL APPROACH

A well-established murine model of localised muscular contraction was utilised. We administered functional tetanus toxin combined with an immunogenic, but functionally inactive, decoy molecule.

KEY RESULTS

Incorporation of the decoy molecule greatly reduces the dose of active toxin required to induce a localised increase in muscle tone in mice vaccinated with the human toxoid vaccine.

CONCLUSION AND IMPLICATIONS

Our results clearly demonstrate that the barriers to developing a tetanus toxin therapeutic are not insurmountable and the technology presented here is the first major step towards realising the therapeutic potential of this powerful neurotoxin. Opening the therapeutic potential of tetanus toxin will have huge implications for the wide range of diseases caused by low-tone muscle.

Practice Patterns of Physicians Using Adjunct Therapies with Botulinum Toxin Injection for Spasticity: A Canadian Multicenter Cross-Sectional Survey

BACKGROUND

Adjunct therapies are nonpharmacological treatments used with botulinum toxin (BoNT) injection that may improve spasticity outcomes. It has been suggested that physicians consider adjunct therapies as a part of comprehensive spasticity management. It is unclear which adjunct therapies are used by physicians in clinical practice.

OBJECTIVE

To determine physician practice patterns and perceptions of use of adjunct therapies following BoNT injection for limb spasticity.

DESIGN

Cross-sectional national survey of current clinical practice using a 22-item questionnaire developed by the authors.

SETTING

Not applicable.

PARTICIPANTS

Survey respondents were physicians actively administering BoNT injections for limb spasticity management across Canada (N = 48).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Types of adjunct therapies used by physicians; physician opinions on barriers to adjunct therapy use, patient preferences, and future research priorities.

RESULTS

Most physicians prescribe home stretching programs, home active exercise programs, and splinting; however, many physicians perceive that these same adjunct therapies are unwanted by patients. A minority of physicians prescribe electrical stimulation (ES), transcutaneous electrical nerve stimulation (TENS), casting, and extracorporeal shockwave therapy; financial limitations and perceived lack of evidence were identified as barriers to their use. Significantly more physicians practicing in academic settings compared with nonacademic, community, and private practice settings used functional ES (59% vs 11%) and TENS (41% vs 0%) as adjunct therapies (P < .05). Research priorities included determining the effectiveness of immediate postinjection application of adjunct therapies (eg, injected muscle activation with ES or stretching) and nutraceuticals.

CONCLUSIONS

Canadian physicians frequently use adjunct therapies in combination with BoNT injection to treat spasticity. Financial and time constraints are identified as barriers to implementation of adjunct therapies that are currently supported by research, and patient preferences may also affect compliance. Future research should focus on adjunct therapies that overcome these barriers.

Vaccine Production to Protect Animals Against Pathogenic Clostridia

Clostridium is a broad genus of anaerobic, spore-forming, rod-shaped, Gram-positive bacteria that can be found in different environments all around the world. The genus includes human and animal pathogens that produce potent exotoxins that cause rapid and potentially fatal diseases responsible for countless human casualties and billion-dollar annual loss to the agricultural sector. Diseases include botulism, tetanus, enterotoxemia, gas gangrene, necrotic enteritis, pseudomembranous colitis, blackleg, and black disease, which are caused by pathogenic Clostridium. Due to their ability to sporulate, they cannot be eradicated from the environment. As such, immunization with toxoid or bacterin-toxoid vaccines is the only protective method against infection. Toxins recovered from Clostridium cultures are inactivated to form toxoids, which are then formulated into multivalent vaccines. This review discusses the toxins, diseases, and toxoid production processes of the most common pathogenic Clostridium species, including Clostridiumbotulinum, Clostridiumtetani, Clostridiumperfringens, Clostridiumchauvoei, Clostridiumsepticum, Clostridiumnovyi and Clostridiumhemolyticum.

Progress in Applying the Three Rs to the Potency Testing of Botulinum Toxin Type A

Botulinum toxin type A (BTA) is being increasingly used for a range of therapeutic purposes and also for cosmetic reasons. For many years, the potency of BTA has been measured by using an LD50 assay in mice. This assay is a cause for concern due to its unpleasant nature and extreme severity, and the requirement for high numbers of mice to be used. Alternatives to this potency assay are presently reviewed with particular reference to the work at the National Institute for Biological Standards and Control (NIBSC), and to recent work by the UK manufacturer of the substance. An in vivo local paralysis assay with considerably less severity has been developed and is in use at the NIBSC. Alternative, ex vivo functional assays in use include the measurement of BTA-induced paralysis of neurally-stimulated rodent diaphragm or rat intercostal muscle. The latter method has the advantage of allowing more preparations to be derived from one animal. However, these ex vivo methods have not yet been fully validated and accepted by regulatory agencies as potency assays. Endopeptidase assays, although not measuring muscle paralysis directly, may provide a very useful consistency test for batch release and may replace the routine use of the LD50 test for that purpose. These assays measure the cleavage of the SNAP-25 protein (the final stage of BTA action), and have been validated for batch release by the National Control Laboratory (NIBSC), and are in regular use there. ELISA assays, used alongside the endopeptidase assay, also provide useful confirmatory information on the amounts of functional (and non-functional) BTA present. The UK manufacturer is further validating its endopeptidase assay, an ex vivo muscle assay and an ELISA. It is anticipated that their work will lead to a change in the product license, hopefully within the next two years, and will form a critical milestone towards the end of the LD50 potency test.

Adjuvant treatments associated with botulinum toxin injection for managing spasticity: An overview of the literature

BACKGROUND AND OBJECTIVE

A wide range of adjunct therapies after botulinum toxin administration have been proposed. The aim of the present paper is to provide an overview of major writings dealing with adjuvant (non-pharmacological) treatments associated with botulinum toxin for managing spasticity in order to provide some up-to-date information about the usefulness of the most commonly used procedures.

METHODS

The literature in PubMed was searched with the MeSH terms botulinum toxins, muscle spasticity, physical therapy modalities, and rehabilitation. The results were limited to studies focusing on adjuvant treatments associated with botulinum toxin for managing spasticity. We excluded papers on the use of non-drug treatments for spasticity not associated with botulinum toxin serotype A (BoNT-A) injection. Relevant literature known to the authors along with this complementary search represented the basis for this overview of the literature.

RESULTS

Adhesive taping and casting effectively improved the botulinum toxin effect in patients with upper- and lower-limb spasticity. There is level 1 evidence that casting is better than taping for outcomes including spasticity, range of motion and gait. However, consensus about their most appropriate timing, duration, target and material is lacking. In terms of physical modalities combined with botulinum toxin injection, we found level 1 evidence that extracorporeal shock wave therapy is better than electrical stimulation for some post-injection outcomes including spasticity and pain. Furthermore, electrical stimulation of injected muscles might be useful to boost the toxin effect. However, the best stimulation protocol has not been defined. In addition, we found level 2b evidence that whole-body vibration therapy might reduce spasticity with cerebral palsy.

CONCLUSION

Future research in this field should focus on investigating the most appropriate post-injection treatment protocol for each goal to achieve.

Evidence and experience with onabotulinumtoxinA in chronic migraine: Recommendations for daily clinical practice

OnabotulinumtoxinA has been demonstrated to be effective as a preventive treatment in patients with chronic migraine (CM). Five years after the approval of onabotulinumtoxinA in Spain, the Headache Study Group of the Spanish Society of Neurology considered it worthwhile to gather a group of experts in treating patients with CM in order to draw up, based on current evidence and our own experience, a series of guidelines aimed at facilitating the use of the drug in daily clinical practice. For this purpose, we posed 12 questions that we ask ourselves as doctors, and which we are also asked by our patients. Each author responded to one question, and the document was then reviewed by everyone. We hope that this review will constitute a practical tool to help neurologists treating patients with CM.

The Molecular Basis of Toxins' Interactions with Intracellular Signaling via Discrete Portals

An understanding of the molecular mechanisms by which microbial, plant or animal-secreted toxins exert their action provides the most important element for assessment of human health risks and opens new insights into therapies addressing a plethora of pathologies, ranging from neurological disorders to cancer, using toxinomimetic agents. Recently, molecular and cellular biology dissecting tools have provided a wealth of information on the action of these diverse toxins, yet, an integrated framework to explain their selective toxicity is still lacking. In this review, specific examples of different toxins are emphasized to illustrate the fundamental mechanisms of toxicity at different biochemical, molecular and cellular- levels with particular consideration for the nervous system. The target of primary action has been highlighted and operationally classified into 13 sub-categories. Selected examples of toxins were assigned to each target category, denominated as portal, and the modulation of the different portal’s signaling was featured. The first portal encompasses the plasma membrane lipid domains, which give rise to pores when challenged for example with pardaxin, a fish toxin, or is subject to degradation when enzymes of lipid metabolism such as phospholipases A₂ (PLA₂) or phospholipase C (PLC) act upon it. Several major portals consist of ion channels, pumps, transporters and ligand gated ionotropic receptors which many toxins act on, disturbing the intracellular ion homeostasis. Another group of portals consists of G-protein-coupled and tyrosine kinase receptors that, upon interaction with discrete toxins, alter second messengers towards pathological levels. Lastly, subcellular organelles such as mitochondria, nucleus, protein- and RNA-synthesis machineries, cytoskeletal networks and exocytic vesicles are also portals targeted and deregulated by other diverse group of toxins. A fundamental concept can be drawn from these seemingly different toxins with respect to the site of action and the secondary messengers and signaling cascades they trigger in the host. While the interaction with the initial portal is largely determined by the chemical nature of the toxin, once inside the cell, several ubiquitous second messengers and protein kinases/ phosphatases pathways are impaired, to attain toxicity. Therefore, toxins represent one of the most promising natural molecules for developing novel therapeutics that selectively target the major cellular portals involved in human physiology and diseases.

Effect of electrical stimulation as an adjunct to botulinum toxin type A in the treatment of adult spasticity: a systematic review

OBJECTIVE

To investigate whether electrical stimulation (ES) as an adjunct to BTX-A boosts botulinum activity and whether the combined therapeutic procedure is more effective than BTX-A alone in reducing spasticity in adult subjects.

DATA SOURCES

A search was conducted in PubMed, EMBASE, Cochrane Central Register, and CINAHL from January 1966 to January 2016.

STUDY SELECTION

Only randomized controlled studies (RCT) involving the combination of BTX-A and ES were considered. RCTs were excluded if BTX plus ES was investigated in animals or healthy subjects; certain techniques were used as an adjunct to BTX-A, but ES was not used; BTX-A or ES were compared but were not used in combination. ES was divided into neuromuscular stimulation (NMS), functional electrical stimulation (FES), and transcutaneous electrical nerve stimulation (TENS). Two authors independently screened all search results and reviewed study characteristics using the Physiotherapy Evidence Database (PEDro) scale.

RESULTS

Fifteen RCTs were pinpointed and nine studies were included. Trials varied in methodological quality, size, and outcome measures used. ES was used in the form of NMS and FES in seven and two studies, respectively. No study investigating BTX-A plus TENS was found. BTX-A plus ES produced significant reduction in spasticity on the Ashworth Scale (AS) and on the modified AS in seven studies, but only four showed high quality on the PEDro scale. Significant reduction in compound muscular action potential (CMAP) amplitude was detected after BTX-A plus ES in two studies.

CONCLUSIONS

ES as an adjunctive therapy to BTX-A may boost BTX-A action in reducing adult spasticity, but ES variability makes it difficult to recommend the combined therapy in clinical practice. Implications for rehabilitation Electrical stimulation (ES) as adjunct to botulinum toxin type A (BTX-A) injections may boost neurotoxin action in treating adult spasticity. Given the variability of ES characteristics and the paucity of high-quality trials, it is difficult to support definitively the use of BTX-A plus ES to potentiate BTX-A effect in clinical practice. A vast array of rehabilitation interventions combined with BTX-A have been provided in reducing spasticity, but the present evidence is not sufficient to recommend any combined therapeutic strategy.

Tetanus toxin production is triggered by the transition from amino acid consumption to peptides

Bacteria produce some of the most potent biomolecules known, of which many cause serious diseases such as tetanus. For prevention, billions of people and countless animals are immunised with the highly effective vaccine, industrially produced by large-scale fermentation. However, toxin production is often hampered by low yields and batch-to-batch variability. Improved productivity has been constrained by a lack of understanding of the molecular mechanisms controlling toxin production. Here we have developed a reproducible experimental framework for screening phenotypic determinants in Clostridium tetani under a process that mimics an industrial setting. We show that amino acid depletion induces production of the tetanus toxin. Using time-course transcriptomics and extracellular metabolomics to generate a 'fermentation atlas' that ascribe growth behaviour, nutrient consumption and gene expression to the fermentation phases, we found a subset of preferred amino acids. Exponential growth is characterised by the consumption of those amino acids followed by a slower exponential growth phase where peptides are consumed, and toxin is produced. The results aim at assisting in fermentation medium design towards the improvement of vaccine production yields and reproducibility. In conclusion, our work not only provides deep fermentation dynamics but represents the foundation for bioprocess design based on C. tetani physiological behaviour under industrial settings.

Cellular Protection of SNAP-25 against Botulinum Neurotoxin/A: Inhibition of Thioredoxin Reductase through a Suicide Substrate Mechanism

Botulium neurotoxins (BoNTs) are among the most lethal toxins known to man. They are comprised of seven serotypes with BoNT/A being the most deadly; yet, there is no approved therapeutic for their intoxication or one that has even advanced to clinical trials. Botulinum neurotoxicity is ultimately governed through light chain (LC) protease SNARE protein cleavage leading to a loss of neurotransmitter release. Pharmacological attempts to ablate BoNT/A intoxication have sought to either nullify cellular toxin entry or critical biochemical junctions found within its intricate mechanism of action. In these regards, reports have surfaced of nonpeptidic small molecule inhibitors, but few have demonstrated efficacy in neutralizing cellular toxicity, a key prerequisite before rodent lethality studies can be initiated. On the basis of a lead discovered in our BoNT/A cellular assay campaign, we investigated a family of N-hydroxysuccinimide inhibitors grounded upon structure activity relationship (SAR) fundamentals. Molecules stemming from this SAR exercise were theorized to be protease inhibitors. However, this proposition was overturned on the basis of extensive kinetic analysis. Unexpectedly, inhibitor data pointed to thioredoxin reductase (TrxR), an essential component required for BoNT protease translocation. Also unforeseen was the inhibitors' mechanism of action against TrxR, which was found to be brokered through a suicide-mechanism utilizing quinone methide as the inactivating element. This new series of TrxR inhibitors provides an alternative means to negate the etiological agent responsible for BoNT intoxication, the LC protease.

Experiences with CPP-Based Self Assembling Peptide Systems for Topical Delivery of Botulinum Toxin

Considerations in rational designs of CPP-based transcutaneous delivery systems are described. Impact of design considerations of nonclinical and clinical results are presented in detail.

Botulinum neurotoxin type A modulates vesicular release of glutamate from satellite glial cells

This study investigated the presence of cell membrane docking proteins synaptosomal-associated protein, 25 and 23 kD (SNAP-25 and SNAP-23) in satellite glial cells (SGCs) of rat trigeminal ganglion; whether cultured SGCs would release glutamate in a time- and calcium-dependent manner following calcium-ionophore ionomycin stimulation; and if botulinum neurotoxin type A (BoNTA), in a dose-dependent manner, could block or decrease vesicular release of glutamate. SGCs were isolated from the trigeminal ganglia (TG) of adult Wistar rats and cultured for 7 days. The presence of SNAPs in TG sections and isolated SGCs were investigated using immunohistochemistry and immunocytochemistry, respectively. SGCs were stimulated with ionomycin (5 μM for 4, 8, 12 and 30 min.) to release glutamate. SGCs were then pre-incubated with BoNTA (24 hrs with 0.1, 1, 10 and 100 pM) to investigate if BoNTA could potentially block ionomycin-stimulated glutamate release. Glutamate concentrations were measured by ELISA. SNAP-25 and SNAP-23 were present in SGCs in TG sections and in cultured SGCs. Ionomycin significantly increased glutamate release from cultured SGCs 30 min. following the treatment (P < 0.001). BoNTA (100 pM) significantly decreased glutamate release (P < 0.01). Results from this study demonstrated that SGCs, when stimulated with ionomycin, released glutamate that was inhibited by BoNTA, possibly through cleavage of SNAP-25 and/or SNAP-23. These novel findings demonstrate the existence of vesicular glutamate release from SGCs, which could potentially play a role in the trigeminal sensory transmission. In addition, interaction of BoNTA with non-neuronal cells at the level of TG suggests a potential analgesic mechanism of action of BoNTA.

Treatment of compensatory hyperhidrosis after sympathectomy with botulinum toxin and anticholinergics

PURPOSE

Compensatory hyperhidrosis (CH) is the most common adverse complication of sympathectomy. It often has a major negative impact on life quality. No efficient treatment of CH is available. We report nine cases of CH after sympathectomy, which were treated with botulinum toxin A/B (BTX) and anticholinergics.

METHODS

The patients responded to a dermatology life quality index (DLQI) questionnaire before injections with BTX and 3 weeks after treatment. At the follow-up visit, the participants also ranked the effect of the treatment on a five-grade scale. Three patients had residual sweating after BTX treatment, and received additional anticholinergics at the follow-up visit. Those subjects eventually had a third evaluation with the DLQI.

RESULTS

The DLQI score was, on average, 16.4 before treatment and decreased to 4.8 after BTX injections. Eight out of nine patients were satisfied with the treatment. The average DLQI score decreased to 2.2 when the patients with residual sweating (n = 3) received additional anticholinergics. Adverse events from BTX were mild and temporary, but dry mouth was substantial in one patient using anticholinergics.

CONCLUSIONS

A combination of BTX A/B and anticholinergics alleviated the hyperhidrosis with minor side-effects. We consider this treatment safe, effective, and well tolerated.

Botulinum toxin for neuropathic pain and spasticity: an overview

In recent years, a large body of data has surfaced reporting the therapeutic benefit of botulinum toxin injection in multiple conditions. The aim of this review is: to summarize the highest quality literature pertaining to clinical application of botulinum toxin in neuropathic pain conditions including postherpetic neuralgia, trigeminal neuralgia, diabetic polyneuropathy, post-traumatic neuralgia, carpal tunnel syndrome, complex regional pain syndrome, phantom limb and stump pain, and occipital neuralgia; to provide an overview of the clinical trials using botulinum toxin in adult spasticity; and to assign levels of evidence according to the American Academy of Neurology guidelines. In summary, there is level A evidence for established efficacy in postherpetic neuralgia and adult spasticity; level B evidence for probable efficacy in trigeminal neuralgia and post-traumatic neuralgia; level B evidence for probable lack of efficacy in carpal tunnel syndrome; level C evidence for possible efficacy in diabetic polyneuropathy; and level U (insufficient) evidence in complex regional pain syndrome, phantom limb and stump pain, and occipital neuralgia.

The molecular machinery of neurotransmitter release (Nobel lecture)

The most important property of synaptic transmission is its speed, which is crucial for the overall workings of the brain. In his Nobel Lecture, T. C. Südhof explains how the synaptic vesicle and the plasma membrane undergo rapid fusion during neurotransmitter release and how this process is spatially organized, such that opening of Ca(2+) -channels allows rapid translation of the entering Ca(2+) signal into a fusion event.

Recent developments in cell-based assays and stem cell technologies for botulinum neurotoxin research and drug discovery

Botulinum neurotoxins (BoNTs) are exceptionally potent inhibitors of neurotransmission, causing muscle paralysis and respiratory failure associated with the disease botulism. Currently, no drugs are available to counter intracellular BoNT poisoning. To develop effective medical treatments, cell-based assays provide a valuable system to identify novel inhibitors in a time- and cost-efficient manner. Consequently, cell-based systems including immortalized cells, primary neurons and stem cell-derived neurons have been established. Stem cell-derived neurons are highly sensitive to BoNT intoxication and represent an ideal model to study the biological effects of BoNTs. Robust immunoassays are used to quantify BoNT activity and play a central role during inhibitor screening. In this review, we examine recent progress in physiologically relevant cell-based assays and high-throughput screening approaches for the identification of both direct and indirect BoNT inhibitors.

Pilot study of topical acetyl hexapeptide-8 in the treatment for blepharospasm in patients receiving botulinum toxin therapy

BACKGROUND AND PURPOSE

Injectable botulinum neurotoxin (BoNT) is the principal effective treatment for blepharospasm (BSP). This trial explores the safety and efficacy of topical acetyl hexapeptide-8 (AH8), a competitive SNAP25 inhibitor, as a potential new therapy in BSP.

METHODS

Double-blind, placebo-controlled, randomized trial of daily topical application of AH8 in 24 patients with BSP. The primary outcome was time to return to baseline Jankovic Blepharospasm Rating Scale (JBRS) after a BoNT injection simultaneously with the initiation of AH8. Patients displaying a strictly regular pattern of response to 3-monthly injections of BoNT were included.

RESULTS

There were no significant adverse events. There was a trend for longer time until return to baseline JBRS after injection in the active group compared to placebo (3.7 months vs. 3.0 months), and for better scores in the active group. One-third (4/12) of the patients in the active group had a considerable extension of symptom control after BoNT (range: 3.3-7.1 months).

CONCLUSIONS

Topical AH8 is safe and promising for extending the duration of action of BoNT therapy for BSP.

SBOTE study: extracorporeal shock wave therapy versus electrical stimulation after botulinum toxin type a injection for post-stroke spasticity-a prospective randomized trial

Research is on-going to identify new methods of biostimulation to increase the effect of botulinum toxin type A (BTX-A) in the treatment of spasticity. The Spasticity treated by Botulinum Toxin and ESWT (SBOTE) study is a prospective, randomized controlled trial assessing the effectiveness of extracorporeal shock wave therapy (ESWT) given immediately after BTX-A injections compared with electrical stimulation (ES) given immediately after BTX-A therapy for the management of focal upper limb spasticity in stroke patients. ES was given for 30 min twice a day for 5 days starting at 5 Hz; ESWT was given once a day for 5 days. At study follow-up, patients treated with BTX-A injections and ESWT showed a statistically greater significance and continuous decrease of spasticity measure (modified Ashworth scale [MAS]: 1.37, 1.75 and 1.58 at 15, 30 and 90 days post-treatment, respectively), of spasms (spasm frequency scale [SFS]: 0.8 and 0.25 at 30 and 90 days post-treatment, respectively) and of pain (visual analogue scale [VAS]: 1.94 and 1.87 at 30 and 90 days, respectively) compared with patients treated with BTX-A injections and ES (MAS: 2.37, 2.18 and 2.18, respectively) (p < 0.05) (SFS: 1.5 and 1.06, respectively) (p < 0.05) (VAS: 2.44 and 2.69 respectively) (p < 0.05). ESWT enhances the effect of BTX-A to a greater extent than ES, probably by modulating rheology of the muscle and neurotransmission at the neuromuscular junction.

Generalised tetanus in a 2-week-old foal: use of physiotherapy to aid recovery

A 2-week-old Estonian Draft foal presented with signs of severe generalised tetanus, recumbency and inability to drink. The suspected source of infection was the umbilicus. Medical treatment was administered, including tetanus antitoxin, antimicrobial therapy and phenobarbital to control tetanic spasms. In addition, an intensive physiotherapy program was carried out during the recovery period. Techniques designed for syndromes involving upper motor neuron spasticity in humans were applied. Exercises aimed at weight-bearing and mobility were executed with the help of a walking-frame. The foal made a complete recovery. To our knowledge, this is the first report of the use of physiotherapy in the treatment of tetanus in horses.

Miscellaneous neurologic or neuromuscular disorders in horses

NMD is an important cause of morbidity in horses. Signs of dysfunction could be variable depending on the specific area affected. NM disease can go unrecognized if a thorough evaluation is not performed in diseased horses. Electrodiagnostic testing is an area that has the potential to document and improve our understanding of NM disease yet is uncommonly performed. Keeping an open and observant mind will enhance our ability to search and find answers.

Botulinum toxin decreases hyperalgesia and inhibits P2X3 receptor over-expression in sensory neurons induced by ventral root transection in rats

OBJECTIVES

We aim to determine the effects of Botulinum toxin type A (BTX-A) on neuropathic pain behavior and the expression of P2X(3) receptor in dorsal root ganglion (DRG) in rats with neuropathic pain induced by L5 ventral root transection (L5 VRT).

METHODS

Neuropathic pain was induced by L5 VRT in male Sprague-Dawley rats. Either saline or BTX-A was administered to the plantar surface. Behavioral tests were conducted preoperatively and at predefined postoperative days. The expression of P2X(3) receptors in DRG neurons was detected by immunoreactivity at postoperative days 3, 7, 14, and 21.

RESULTS

The number of positive P2X(3) neurons in the ipsilateral L5 DRG increased significantly after L5 VRT (P<0.001). This increase persisted for at least 3 weeks after the operation. No significant changes in P2X(3) expression were detected in the contralateral L5, or in the L4 DRGs bilaterally. Subcutaneous administration of BTX-A, performed on the left hindpaw at days 4, 8, or 16 post VRT surgery, significantly reduced mechanical allodynia bilaterally and inhibited P2X(3) over-expression induced by L5 VRT.

CONCLUSIONS

L5 VRT led to over-expression of P2X(3) receptors in the L5 DRG and bilateral mechanical allodynia in rats. Subcutaneous injection of BTX-A significantly reversed the neuropathic pain behavior and the over-expression of P2X(3) receptor in nociceptive neurons. These data not only show over-expression of purinergic receptors in the VRT model of neuropathic pain but also reveal a novel mechanism of botulinum toxin action on nociceptive neurons.

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.

Long-term follow-up of botulinum toxin therapy for focal hand dystonia: outcome at 10 years or more

BACKGROUND

Previous studies have explored the efficacy and safety of botulinum neurotoxin (BoNT) treatment for Focal hand dystonia (FHD), but none have followed a large number of patients for 10 years or more.

METHODS

Retrospective study, with benefit and weakness assessed on a 0 to 4 subjective scale. Demographic, clinical and treatment characteristics were analyzed using t tests and Pearson correlations.

RESULTS

Twenty FHD patients had 10 years or longer treatment. Interinjection intervals were variable. Musicians were more likely to wait longer between injections and had less complex dystonia. There was a trend for larger benefit in women and with shorter intervals. The dose increased over time. Dystonia characteristics did not predict response or side-effects, but benefit magnitude predicted longer compliance. No serious side-effects or antibody-mediated resistance occurred.

CONCLUSION

This is the longest reported period of BoNT treatment in the largest FHD cohort. BoNT therapy for FHD remains safe and effective after more than a decade of treatment.

Nonclinical and clinical experiences with CPP-based self-assembling peptide systems in topical drug development

Considerations in rational designs of CPP-based transcutaneous delivery systems are described. Impact of design considerations of nonclinical and clinical results are presented in detail.

Botulinum toxin in the treatment of sweat-worsened foot problems in patients with epidermolysis bullosa simplex and pachyonychia congenita

BACKGROUND

Painful foot blistering is a common problem in patients with epidermolysis bullosa simplex (EBS) and pachyonychia congenita (PC). Hyperhidrosis, a condition which can be effectively blocked by plantar injections of botulinum toxin (Btx), often exacerbates the blistering.

OBJECTIVES

A retrospective evaluation of the effects of Btx injections in 14 patients with EBS and PC with foot blisters and painful callosities.

METHODS

After informed consent, patients with EBS (n = 6) and PC (n = 8), aged 7-66 years, who had received Btx therapy at our centre since 2003, were included. The treatment consisted of multiple plantar injections of Btx A or Btx B after prior regional or general anaesthesia. Patients were interviewed about the treatment effect and were asked to score the improvement from 0 to 5, where 5 is 'excellent'. One patient with PC with painful callosities was studied by magnetic resonance (MR) spectroscopic microimaging before and after Btx injections to disclose any underlying blisters.

RESULTS

In total, 76 treatments were evaluated (one to 19 sessions per patient). Thirteen patients (93%) reported reduced plantar blistering and pain; the improvement score was ≥ 4 in four of six patients with EBS and six of eight patients with PC. The mean effect duration was 3 months. No adverse events, apart from mild anticholinergic side-effects in two patients, were noted. MR spectroscopic microimaging showed disappearance of intraepidermal blistering after Btx therapy.

CONCLUSIONS

Plantar injection of Btx is an efficient, long-lasting and safe treatment of painful blistering and callosities in EBS and PC that can be given repeatedly without loss of efficacy.

Botulinum neurotoxin for pain management: insights from animal models

The action of botulinum neurotoxins (BoNTs) at the neuromuscular junction has been extensively investigated and knowledge gained in this field laid the foundation for the use of BoNTs in human pathologies characterized by excessive muscle contractions. Although much more is known about the action of BoNTs on the peripheral system, growing evidence has demonstrated several effects also at the central level. Pain conditions, with special regard to neuropathic and intractable pain, are some of the pathological states that have been recently treated with BoNTs with beneficial effects. The knowledge of the action and potentiality of BoNTs utilization against pain, with emphasis for its possible use in modulation and alleviation of chronic pain, still represents an outstanding challenge for experimental research. This review highlights recent findings on the effects of BoNTs in animal pain models.

Botulinum toxin type A reduces pain supersensitivity in experimental diabetic neuropathy: bilateral effect after unilateral injection

We investigated antinociceptive activity of botulinum toxin type A (BTX-A) in a model of diabetic neuropathic pain in rats. Male Wistar rats were made diabetic by a single intraperitoneal injection of streptozotocin (80mg/kg). Sensitivity to mechanical and thermal stimuli was measured with the paw-pressure and hot-plate test, respectively. The formalin test was used to measure sensitivity to chemical stimuli. Diabetic animals with pain thresholds lower for at least 25% compared to the non-diabetic group were considered neuropathic and were injected with BTX-A either subcutaneously (3, 5 and 7U/kg) or intrathecally (1U/kg). Mechanical and thermal sensitivity was measured at several time-points. After peripheral application, BTX-A (5 and 7U/kg) reduced mechanical and thermal hypersensitivity not only on ipsilateral, but on contralateral side, too. The antinociceptive effect started 5days following BTX-A injection and lasted at least 15days. Formalin-induced hypersensitivity in diabetic animals was abolished as well. When applied intrathecally, BTX-A (1U/kg) reduced diabetic hyperalgesia within 24h supporting the assumption of retrograde axonal transport of BTX-A from the peripheral site of injection to central nervous system. The results presented here demonstrate the long-lasting pain reduction after single BTX-A injection in the animals with diabetic neuropathy. The bilateral pain reduction after unilateral toxin application and the effectiveness of lower dose with the faster onset after the intrathecal injection suggest the involvement of the central nervous system in the antinociceptive action of BTX-A in painful diabetic neuropathy.

Recombinant derivatives of botulinum neurotoxin A engineered for trafficking studies and neuronal delivery

Work from multiple laboratories has clarified how the structural domains of botulinum neurotoxin A (BoNT/A) disable neuronal exocytosis, but important questions remain unanswered. Because BoNT/A intoxication disables its own uptake, light chain (LC) does not accumulate in neurons at detectable levels. We have therefore designed, expressed and purified a series of BoNT/A atoxic derivatives (ad) that retain the wild type features required for native trafficking. BoNT/A1ad(ek) and BoNT/A1ad(tev) are full length derivatives rendered atoxic through double point mutations in the LC protease (E(224)>A; Y(366)>A). DeltaLC-peptide-BoNT/A(tev) and DeltaLC-GFP-BoNT/A(tev) are derivatives wherein the catalytic portion of the LC is replaced with a short peptide or with GFP plus the peptide. In all four derivatives, we have fused the S6 peptide sequence GDSLSWLLRLLN to the N-terminus of the proteins to enable site-specific attachment of cargo using Sfp phosphopantetheinyl transferase. Cargo can be attached in a manner that provides a homogeneous derivative population rather than a polydisperse mixture of singly and multiply-labeled molecular species. All four derivatives contain an introduced cleavage site for conversion into disulfide-bonded heterodimers. These constructs were expressed in a baculovirus system and the proteins were secreted into culture medium and purified to homogeneity in yields ranging from 1 to 30 mg per liter. These derivatives provide unique tools to study toxin trafficking in vivo, and to assess how the structure of cargo linked to the heavy chain (HC) influences delivery to the neuronal cytosol. Moreover, they create the potential to engineer BoNT-based molecular vehicles that can target therapeutic agents to the neuronal cytoplasm.

AMPA and metabotropic excitoxicity explain subplate neuron vulnerability

Cerebral hypoxia-ischemia results in unique patterns of injury during development owing to selective vulnerability of specific cell populations including subplate neurons. To evaluate the contribution of glutamate excitotoxicity, we studied enriched cultures of subplate neurons in comparison with cortical neurons, deriving expression profiles for glutamate receptor subunits by microarray and immunoblot. The excitotoxic potency of specific glutamate receptors was tested with selective agonists and antagonists. After 1 week in culture, subplate neurons are more sensitive to oxygen-glucose deprivation than cortical neurons, confirming in vivo observations. Subplate and cortical neurons are equally sensitive to glutamate and insensitive to NMDA. Subplate neurons are more sensitive than cortical neurons to AMPA and express twofold less GluR2. Subplate neurons express significantly more mGluR3, a receptor proposed to be protective. Despite this increased expression, group II mGluR agonists increase subplate neuron death and antagonists lessen glutamate excitotoxicity, suggesting a novel mechanism for subplate vulnerability.

Central origin of the antinociceptive action of botulinum toxin type A

Here we provide behavioural evidence for an axonal transport and the central origin of the antinociceptive effect of botulinum toxin type A (BTX-A). In rats we investigated the effectiveness of BTX-A on "mirror pain" induced by unilateral repeated intramuscular acidic saline injections (pH 4.0). Since experimental evidence suggest that bilateral pain induced by acidic saline is of central origin, peripheral application of BTX-A should have no effect on this type of pain. However, here we demonstrated that the unilateral subcutaneous BTX-A (5U/kg) application diminished pain on the ipsilateral, and on the contralateral side too. When injected into the proximal part of a distally cut sciatic nerve, BTX-A still reduced pain on the contralateral side. Colchicine, an axonal transport blocker, when injected into the ipsilateral sciatic nerve, prevented the effect of the peripheral BTX-A injection on both sides. Additionally, when BTX-A (1U/kg) was applied intrathecally in the lumbar cerebrospinal fluid, the bilateral hyperalgesia was also reduced. The results demonstrate the necessity of retrograde axonal transport and involvement of the central nervous system for the antinociceptive activity of BTX-A.

Activation of the tonic GABAC receptor current in retinal bipolar cell terminals by nonvesicular GABA release

Within the second synaptic layer of the retina, bipolar cell (BC) output to ganglion cells is regulated by inhibitory input to BC axon terminals. GABA(A) receptors (GABA(A)Rs) mediate rapid synaptic currents in BC terminals, whereas GABA(C) receptors (GABA(C)Rs) mediate slow evoked currents and a tonic current, which is strongly regulated by GAT-1 GABA transporters. We have used voltage-clamp recordings from BC terminals in goldfish retinal slices to determine the source of GABA for activation of these currents. Inhibition of vesicular release with concanamycin A or tetanus toxin significantly inhibited GABA(A)R inhibitory postsynaptic currents and glutamate-evoked GABA(A)R and GABA(C)R currents but did not reduce the tonic GABA(C)R current, which was also not dependent on extracellular Ca(2+). The tonic current was strongly potentiated by inhibition of GABA transaminase, under both normal and Ca(2+)-free conditions, and was activated by exogenous taurine; however inhibition of taurine transport had little effect. The tonic current was unaffected by GAT-2/3 inhibition and was potentiated by GAT-1 inhibition even in the absence of vesicular release, indicating that it is unlikely to be evoked by reversal of GABA transporters or by ambient GABA. In addition, GABA release does not appear to occur via hemichannels or P2X(7) receptors. BC terminals therefore exhibit two forms of GABA(C)R-mediated inhibition, activated by vesicular and by nonvesicular GABA release, which are likely to have distinct functions in visual signal processing. The tonic GABA(C)R current in BC terminals exhibits similar properties to tonic GABA(A)R and glutamate receptor currents in the brain.

Dose equivalence of two commercial preparations of botulinum neurotoxin type A: time for a reassessment?

BACKGROUND

The units of different preparations of botulinum neurotoxin type A (BoNT-A) have different potencies, and dosing recommendations for each product are not interchangeable. Historically, there has been debate concerning the dose-equivalence ratio that should be used in clinical practice.

METHODS

Published evidence was considered to establish an appropriate dose-conversion ratio for the two main commercially available preparations of BoNT-A--Dysport (Dp) and Botox (Bx).

RESULTS

Four key areas of evidence were identified: nonclinical and preclinical studies; studies exploring the diffusion characteristics and effects of complexing proteins; comparative experimental data from human studies; and clinical studies. Nonclinical data indicate that the principal reasons for differences in unit potency between the two products are dilution artefacts in the mouse assay. Use of saline as a diluent, at high dilutions, results in significant loss of potency in the Bx assay, whereas use of gelatin phosphate buffer in the Dp assay procedure protects the toxin during dilution. The published data on mouse assays show a Dp : Bx unit ratio range of 2.3-2.5 : 1 in saline and 1.8-3.2 : 1 in gelatin phosphate buffer. Data indicate that complexing proteins or size of the complex, which is highly pH sensitive, play no role in toxin diffusion and that Dp and Bx have similar diffusion characteristics when used at comparable doses. Randomized, controlled clinical studies indicate that 3 : 1 is more appropriate than 4 : 1, but the two products are not equivalent at this ratio. Comparative human experimental studies using the extensor digitorum brevis test, facial lines and anhidrotic action halo tests support dose-conversion ratios less than 3 : 1.

LIMITATIONS

Data comparing dose equivalence ratios from the non-clinical setting should be extrapolated into the clinical setting with some caution.

CONCLUSIONS

Dose-conversion ratios between Dp and Bx of 4 : 1 and greater are not supported by the recent literature.

NeuroBloc/Myobloc: unique features and findings

This review outlines factors that differentiate botulinum toxin serotypes and focuses on the unique features of the commercially available form of BoNT-B (i.e., Myobloc/NeuroBloc). A series of preclinical studies in Cynomolgus monkeys are reviewed. Each of these studies used electrophysiologic measures of changes in the compound muscle action potential (CMAP) following supramaximal nerve stimulation to evaluate the direct effects of the toxin in the injected muscle, as well as the spread of the effects to non-injected muscles. The results of 14 studies were summarized, including several that compared the effects of equivalent doses of BoNT-A and BoNT-B injected into muscles on the opposite side of the same monkey. There is clear evidence that when equivalent doses of BoNT-A and BoNT-B are assessed, there is greater spread to both nearby and remote non-injected muscles associated with BoNT-A. Similar studies in the mouse model demonstrated that high, but non-lethal, doses of BoNT-A unilaterally injected into the foot resulted in spread of the effects across the midline to the opposite non-treated foot, while there was no evidence of bilateral effects with equivalent unilateral injections of BoNT-B. Finally, this review summarizes a series of studies in the trapezius and gastrocnemius muscles of monkeys demonstrating that when doses producing equivalent initial effects of BoNT-A and BoNT-B are compared, the duration of effects and the time course of recovery are almost identical across toxins.

Covalent modifications of antitetanus F(ab')2 fragments with natural and synthetic polyamines and their effects on the antibody endocytosis in cultured HL60 cells

For antibody therapeutics to succeed when intracellular target molecules are involved, a strategy must be applied to increase the delivery of antibodies into cells to reach their targets. Antibody cationization by chemical conjugation of a polyamine could be one such strategy. Both natural polyamines with increasing net charge valencies (putrescine, PUT; spermidine, SPD; and spermine, SPM) and a synthetic polyamine (hexamethylenediamine, HMD) can be used to cationize antibodies, but no comparison of the respective effects of these polyamines on intracellular delivery of antibodies has been performed yet. This study describes the covalent modification of antitetanus F(ab') 2 with these four polyamines using different reaction conditions, and compares the effects of these modifications on antibody interaction with cultured HL60 cells. The cationized antibodies retained > or =80% of the binding activity of the unmodified F(ab') 2 with regard to tetanus toxin, as measured by an antigen-binding capture enzyme immunoassay. This same method was used to quantify the amount of cell-associated F(ab') 2 following incubation with HL60 cells. Cationization was shown to enhance cell interaction of the F(ab') 2 : the higher the number of coupled polyamine molecules, the greater the amount of antibody associated with the cells. Moreover, coupling the F(ab') 2 to the SPD and SPM polyamines had greater effect on cell interaction than coupling the F(ab') 2 to the PUT and HMD diamines. Internalization of the cationized antibodies by the HL60 cells was demonstrated by confocal microscopy. This technique also showed that SPD and SPM were more effective than PUT and HMD in terms of intracellular delivery of the F(ab') 2 . It follows from all these results that electrostatic interaction involving charge density plays a predominant role in the endocytic transport mechanism of the F(ab') 2 modified with these polyamines. However, coupling the F(ab') 2 to SPM and SPD yielded the same maximum effects in terms of cell interaction, although coupling SPM was expected to increase the antibody net charge valency more than coupling SPD. This finding suggests that the effective global charge for the cell interaction and uptake of polyamine-modified antibodies does not simply correspond to the addition of the ionizable amine functions on the coupled polyamines, and that other factors may come into play.

Iatrogenic botulism in a child with spastic quadriparesis

Botulinum toxins are potent neurotoxins used in a variety of neurological disorders. Few pediatric reports have been published to date regarding the potential hazards of therapeutic use of botulinum toxins. We describe the case of a 10-year-old boy who developed systemic weakness following treatment of spasticity with botulinum toxin type B. The patient developed iatrogenic botulism with ptosis, facial diplegia, neck flexor and extensor weakness, and profound hypopharyngeal laxity with respiratory compromise from which he eventually recovered. Clinicians should be mindful of the risk for systemic botulism when using local injections of the neurotoxin.

Botulism diagnostics: from clinical symptoms to in vitro assays

Botulinum neurotoxin (BoNT), which cause the deadly neuroparalytic disease, botulism, is the most toxic substance known to man. BoNT can be used as potential bioterrorism agents, and therefore, pose great threat to national security and public health. Rapid and sensitive detection of BoNTs using molecular and biochemical techniques is an essential component in the diagnosis of botulism, and is yet to be achieved. The most sensitive and widely accepted assay method for BoNTs is mouse bioassay, which takes 4 days to complete. This clearly can not meet the need for clinical diagnosis of botulism, botulinum detection in field conditions, and screening of large scale samples. Consequently, the clinical diagnosis of botulism relies on the clinical symptom development, thus limiting the effectiveness of antitoxin treatment. In response to this critical need, many in vitro methods for BoNT detection are under development. This review is focused on recently developed in vitro detection methods for BoNTs, and emerging new technologies with potential for sensitive and rapid in vitro diagnostics for botulism.