Comparison of two different formulations of botulinum toxin A for the treatment of oesophageal achalasia. The Gismad Achalasia Study Group.
(9/694)
BACKGROUND: Intrasphincteric injection of botulinum toxin has been reported as a safe and effective alternative treatment in oesophageal achalasia, especially in high-risk and elderly patients. AIM: : To compare two formulations of botulinum toxin in the management of achalasia. PATIENTS AND METHODS: We randomly compared the efficacy and safety of 100 U of Botox (Allergan, Irvine, USA) and 250 U of Dysport (Ipsen, Milan, Italy), injected through a sclerotherapy needle at the level of the lower oesophageal sphincter, in 78 consecutive patients with achalasia. Symptom score, oesophageal manometry and 24 h pH-metry were recorded (before and 1 month after therapy). Symptom score was also obtained 6 months after treatment. RESULTS: One month after treatment, the effects of the toxin on symptoms and oesophageal tests were similar for both formulations. Lower oesophageal sphincter pressure decreased from 31 +/- 12 to 18 +/- 5 mmHg after Botox, and from 35 +/- 9 to 18 +/- 10 after Dysport. At the end of the follow-up period (6 months), symptom score decreased from 5 +/- 1.2 to 1.2 +/- 0.8 after Botox and from 5.2 +/- 1.5 to 1.5 +/- 1 after Dysport. Moreover, the percentages of patients who failed to respond to treatment (10% and 17.5%) and who relapsed during follow-up (12% and 24%) did not differ significantly. No patient complained of reflux symptoms after treatment, although abnormal acid exposure was documented in two subjects. CONCLUSIONS: Both formulations of botulinum toxin have comparable efficacy in the treatment of oesophageal achalasia, for up to 6 months of follow-up. (+info)
Botulinum neurotoxin A blocks synaptic vesicle exocytosis but not endocytosis at the nerve terminal.
(10/694)
The supply of synaptic vesicles in the nerve terminal is maintained by a temporally linked balance of exo- and endocytosis. Tetanus and botulinum neurotoxins block neurotransmitter release by the enzymatic cleavage of proteins identified as critical for synaptic vesicle exocytosis. We show here that botulinum neurotoxin A is unique in that the toxin-induced block in exocytosis does not arrest vesicle membrane endocytosis. In the murine spinal cord, cell cultures exposed to botulinum neurotoxin A, neither K(+)-evoked neurotransmitter release nor synaptic currents can be detected, twice the ordinary number of synaptic vesicles are docked at the synaptic active zone, and its protein substrate is cleaved, which is similar to observations with tetanus and other botulinal neurotoxins. In marked contrast, K(+) depolarization, in the presence of Ca(2+), triggers the endocytosis of the vesicle membrane in botulinum neurotoxin A-blocked cultures as evidenced by FM1-43 staining of synaptic terminals and uptake of HRP into synaptic vesicles. These experiments are the first demonstration that botulinum neurotoxin A uncouples vesicle exo- from endocytosis, and provide evidence that Ca(2+) is required for synaptic vesicle membrane retrieval. (+info)
Identification and characterization of functional subunits of Clostridium botulinum type A progenitor toxin involved in binding to intestinal microvilli and erythrocytes.
(11/694)
Clostridium botulinum type A hemagglutinin-positive progenitor toxin consists of three distinct components: neurotoxin (NTX), hemagglutinin (HA), and non-toxic non-HA (NTNH). The HA consists of four subcomponents designated HA1, 2, 3a and 3b. By employing purified toxin and GST-fusion proteins of each HA subcomponent, we found that the HA-positive progenitor toxin, GST-HA1 and GST-HA3b bind to human erythrocytes and microvilli of guinea pig upper small intestinal sections. The HA-positive progenitor toxin and GST-HA1 bind via galactose moieties, GST-HA3b binds via sialic acid moieties. GST-2 and GST-3a showed no detectable binding. (+info)
Expression of Kv1 potassium channels in mouse hippocampal primary cultures: development and activity-dependent regulation.
(12/694)
Excitability and discharge behavior of neurons depends on the highly variable expression pattern of voltage-dependent potassium (Kv) channels throughout the nervous system. To learn more about distribution, development, and activity-dependent regulation of Kv channel subunit expression in the rodent hippocampus, we studied the protein expression of members of the Kv1 subfamily in mouse hippocampus in situ and in primary cultures. In adult hippocampus, Kv1 (1-6) channel alpha-subunits were present, whereas at postnatal day 2, none of these proteins could be detected in CA1-CA3 and dentate gyrus. Kv1.1 was the first channel to be observed at postnatal day 6. The delayed postnatal expression and most of the subcellular distribution observed in hippocampal sections were mimicked by cultured hippocampal neurons in which Kv channels appeared only after 10 days in vitro. This developmental upregulation was paralleled by a dramatic increase in total K(+) current, as well as an elevated GABA release in the presence of 4-aminopyridine. Thus, the developmental profile, subcellular localization, and functionality of Kv1 channels in primary culture of hippocampus closely resembles the in situ situation. Impairing secretion by clostridial neurotoxins or blocking activity by tetrodotoxin inhibited the expression of Kv1.1, Kv1.2, and Kv1.4, whereas the other Kv1 channels still appeared. This activity-dependent depression was only observed before the initial appearance of the respective channels and lost after they had been expressed. Our data show that hippocampal neurons in culture are a convenient model to study the developmental expression and regulation of Kv1 channels. The ontogenetic regulation and the activity-dependent expression of Kv1.1, Kv1.2, and Kv1.4 indicate that neuronal activity plays a crucial role for the development of the mature Kv channel pattern in hippocampal neurons. (+info)
The C terminus of SNAP25 is essential for Ca(2+)-dependent binding of synaptotagmin to SNARE complexes.
(13/694)
The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins syntaxin and synaptosome-associated protein of 25 kDa (SNAP25) and the vesicle SNARE protein vesicle-associated membrane protein (VAMP) are essential for a late Ca(2+)-dependent step in regulated exocytosis, but their precise roles and regulation by Ca(2+) are poorly understood. Botulinum neurotoxin (BoNT) E, a protease that cleaves SNAP25 at Arg(180)-Ile(181), completely inhibits this late step in PC12 cell membranes, whereas BoNT A, which cleaves SNAP25 at Gln(197)-Arg(198), is only partially inhibitory. The difference in toxin effectiveness was found to result from a reversal of BoNT A but not BoNT E inhibition by elevated Ca(2+) concentrations. BoNT A treatment essentially increased the Ca(2+) concentration required to activate exocytosis, which suggested a role for the C terminus of SNAP25 in the Ca(2+) regulation of exocytosis. Synaptotagmin, a proposed Ca(2+) sensor for exocytosis, was found to bind SNAP25 in a Ca(2+)-stimulated manner. Ca(2+)-dependent binding was abolished by BoNT E treatment, whereas BoNT A treatment increased the Ca(2+) concentration required for binding. The C terminus of SNAP25 was also essential for Ca(2+)-dependent synaptotagmin binding to SNAP25. syntaxin and SNAP25.syntaxin.VAMP SNARE complexes. These results clarify classical observations on the Ca(2+) reversal of BoNT A inhibition of neurosecretion, and they suggest that an essential role for the C terminus of SNAP25 in regulated exocytosis is to mediate Ca(2+)-dependent interactions between synaptotagmin and SNARE protein complexes. (+info)
Inhibition of vesicular secretion in both neuronal and nonneuronal cells by a retargeted endopeptidase derivative of Clostridium botulinum neurotoxin type A.
(14/694)
Clostridial neurotoxins potently and specifically inhibit neurotransmitter release in defined cell types by a mechanism that involves cleavage of specific components of the vesicle docking/fusion complex, the SNARE complex. A derivative of the type A neurotoxin from Clostridium botulinum (termed LH(N)/A) that retains catalytic activity can be prepared by proteolysis. The LH(N)/A, however, lacks the putative native binding domain (H(C)) of the neurotoxin and is thus unable to bind to neurons and effect inhibition of neurotransmitter release. Here we report the chemical conjugation of LH(N)/A to an alternative cell-binding ligand, wheat germ agglutinin (WGA). When applied to a variety of cell lines, including those that are ordinarily resistant to the effects of neurotoxin, WGA-LH(N)/A conjugate potently inhibits secretory responses in those cells. Inhibition of release is demonstrated to be ligand mediated and dose dependent and to occur via a mechanism involving endopeptidase-dependent cleavage of the natural botulinum neurotoxin type A substrate. These data confirm that the function of the H(C) domain of C. botulinum neurotoxin type A is limited to binding to cell surface moieties. The data also demonstrate that the endopeptidase and translocation functions of the neurotoxin are effective in a range of cell types, including those of nonneuronal origin. These observations lead to the conclusion that a clostridial endopeptidase conjugate that can be used to investigate SNARE-mediated processes in a variety of cells has been successfully generated. (+info)
Botulinum toxin (Dysport) treatment of hip adductor spasticity in multiple sclerosis: a prospective, randomised, double blind, placebo controlled, dose ranging study.
(15/694)
OBJECTIVE: To define a safe and effective dose of Dysport for treating hip adductor spasticity. METHODS: Patients with definite or probable multiple sclerosis, and disabling spasticity affecting the hip adductor muscles of both legs, were randomised to one of four treatment groups. Dysport (500, 1000, or 1500 Units), or placebo was administered by intramuscular injection to these muscles. Patients were assessed at entry, and 2, 4 (primary analysis time-point), 8, and 12 weeks post-treatment. RESULTS: A total of 74 patients were recruited. Treatment groups were generally well matched at entry. The primary efficacy variables-passive hip abduction and distance between the knees-improved for all groups. The improvement in distance between the knees for the 1500 Unit group was significantly greater than placebo (p = 0.02). Spasm frequency was reduced in all groups, but muscle tone was reduced in the Dysport groups only. Pain was reduced in all groups, but improvements in hygiene scores were evident only in the 1000 Unit and 1500 Unit groups. Duration of benefit was significantly longer than placebo for all Dysport groups (p<0.05). Adverse events were reported by 32/58 (55%) Dysport patients, and by 10/16 (63%) placebo patients. Compared with the two lower dose groups, twice as many adverse events were reported by the 1500 Unit group (2.7/patient). The incidence of muscle weakness was higher for the 1500 Unit group (36%) than for placebo (6%). The response to treatment was considered positive by two thirds of the patients in the 500 Unit group, and by about half the patients in the other groups. CONCLUSION: Dysport reduced the degree of hip adductor spasticity associated with multiple sclerosis, and this benefit was evident despite the concomitant use of oral antispasticity medication and analgesics. Although evidence for a dose response effect was not statistically significant, there was a clear trend towards greater efficacy and duration of effect with higher doses of Dysport. Dysport treatment was well tolerated, with no major side effects seen at doses up to 1500 Units. The optimal dose for hip adductor spasticity seems to be 500-1000 Units, divided between both legs. (+info)
Injections of botulinum toxin A into the salivary glands improve sialorrhoea in amyotrophic lateral sclerosis.
(16/694)
Sialorrhoea is a socially disabling problem in bulbar amyotrophic lateral sclerosis (ALS). Botulinum toxin A (BoNT/A) was injected into the salivary glands in five patients with bulbar ALS and sialorrhoea. The effect of BoNT/A was measured by the number of paper handkerchiefs used each day and by salivary gland scintigraphy. BoNT/A ameliorated sialorrhoea and quality of life without major adverse effects. BoNT/A may be a relatively safe and effective treatment for sialorrhoea in selected patients. (+info)