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PubMedDate not supplied

Breast feeding and toxigenic intestinal infections: missing links in crib death?

Infant botulism results when Clostridium botulinum spores germinate, colonize the gut, and there produce botulinal toxin, which after absorption causes flaccid muscle paralysis. The observed variation in the severity of the disease was linked to the infant's milk source, in that all sudden death cases indistinguishable from typical crib death occurred in infants who had been formula-fed, whereas the more gradual onset, hospitalized cases occurred in infants who were predominantly breast-fed. Secretory IgA antibody against C. botulinum vegetative cell antigens was found in human milk from mothers of both healthy infants and patients, a finding that further confirms the functioning of the "mucosal immune system" in humans. The hypothesis that some crib deaths might also result from other intestinally produced bacterial toxins was investigated by injecting infant rhesus monkeys with microgram amounts of purified Clostridium difficile toxins A and B; quiet death pathologically consistent with human crib death occurred within 4 hr to 10 hr. This and other evidence suggest that infant botulism may be the prototype of a putative class of heretofore unrecognized diseases, the "toxigenic intestinal infections of infancy." Collectively, these illnesses may account for a modest proportion of crib death, against which human milk may provide relative protection.

Bacterial Proteins↗
PubMed1984

[Food poisoning caused by Clostridium botulinum type E].

The results of a microbiological investigation carried out into a home-canned tuna fish are reported in relation to a suspected botulism case. Toxin of Cl. botulinum type E was detected by mouse toxicity and neutralization tests. The food specimen were also cultured for Cl. botulinum. The isolates was identified as Cl. botulinum type E by biochemical, gas chromatographic and immunological tests. The outbreak in which for the first time in Italy, the Cl. botulinum type E is involved, concerns one person who showed typical signs and symptoms consistent with botulism (abdominal cramps, dilatated pupils, diplopia, dysphagia, paralysis of lower upper limbs). The laboratory results are discussed with relation to environmental characteristics of the micro-organism and their resistance to same chemical and physical factors with are involved in the canning practice.

Adult↗
PubMed1993

[Poisoning after eating sausage in observations from I Clinic of Infectious Diseases of the Slask Academy of Medicine in 1985-1992].

On the basis of our own material and the literature review the analysis of 10 cases of botulism is presented. A mild course of the disease was observed in 40%, a medium-severe course in 30% and a severe course also in 30% of patients. Fatal courses were not recorded. All patients were discharged from the Clinic in the good state of health. Etiopathogenesis, symptomatology and treatment of botulism is discussed. Attention is paid to new diagnostic method.

Adolescent↗
PubMed1997

[Action mechanisms of botulinum neurotoxins and tetanus neurotoxins].

Tetanus (TeNT) neurotoxin and botulinum (BoNT, serotypes A-G) neurotoxins are di-chain bacterial proteins of MW-150 kDa which are also termed as clostridial neurotoxins. They are the only causative agents of two severe neuroparalytic diseases, namely tetanus and botulism. The peripheral muscle spasms which characterise tetanus are due to a blockade of inhibitory (GABAergic and glycinergic) synapses in the central nervous system leading to a motor neurones desinhibition. In contrast, botulism symptoms are only peripheral. They are consequent to a near irreversible and highly selective inhibition of acetyl-choline release at the motor nerve endings innervating skeletal muscles. During the past decade, the cellular and molecular modes of action of clostridial neurotoxins has been near completely elucidated. After a binding step of the neurotoxins to specific membrane acceptors located only on nerve terminals, BoNTs and TeNT are internalized into neurons. Inside their target neurones, the intracellularly active moiety (their light chain) is translocated from the endosomal compartment to the cytosol. The neurotoxins' light chains are zinc-dependent (endopeptidases which are specific for one among three synaptic proteins (VAMP/synaptobrevin, syntaxin or SNAP-25) implicated in neurotransmitter exocytosis. The presence of distinct targets for BoNTs and TeNT correlates well with the observed quantal alterations of neurotransmitter release which characterize certain toxin serotypes. In addition, evidence for a second, non-proteolytic, inhibitory mechanism of action has been provided recently. Most likely, this additional blocking action involves the activation of neurone transglutaminases. Due to their specific action on key proteins of the exocytosis apparatus, clostridial neurotoxins are now widely used as molecular tools to study exocytosis.

Animals↗
PubMed2001

High-throughput fluorogenic assay for determination of botulinum type B neurotoxin protease activity.

Botulinum neurotoxins are responsible for botulism, a flaccid muscular paralysis caused by inhibition of acetylcholine release at the neuromuscular junction. This occurs by cleavage of conserved proteins involved in exocytosis such as synaptobrevin by the zinc metallopeptidase activity of the light chain of some botulinum neurotoxins. Botulism, for which there is presently no therapy available, is a relatively widespread disease that may result in death. Consequently, the development of drugs able to inhibit the hydrolytic activity of these neurotoxins is of great interest. Design and screening of such inhibitors could be largely facilitated by using high-throughput assays. With this aim, a novel in vitro test for quantifying the proteolytic activity of botulinum type B neurotoxin was developed. The substrate is the 60--94 fragment of human synaptobrevin-1 which was modified by introduction of the fluorescent amino acid l-pyrenylalanine in position 74 and a p-nitrophenylalanyl residue as quenching group in position 77. The cleavage of Syb 60-94 [Pya(74), Nop(77)] by the toxin active chain occurs selectively between residues 76 and 77 as in the case of the unmodified synaptobrevin and is directly quantified by measuring the strong fluorescence of the formed metabolite Syb 60-76 [Pya(74)]. This is the easiest, quickest, and cheapest assay described to date for measuring the proteolytic activity of botulinum type B neurotoxin. It can be easily automated for high-throughput screening. Moreover, amounts of about 3.5 pg/ml of botulinum type B neurotoxin could be detected by this method.

Biological Assay↗
PubMed1977

The action of botulinum A neurotoxin on the inhibition by antidromic stimulation of the lumbar monosynaptic reflex.

1. Botulinum toxin type A was injected into gastrocnemius muscles of cats and 2 days later its action on the monosynaptic gastrocnemius reflex and on the recurrent inhibition was investigated. 2. In early local botulism, no significant change in the monosynaptic gastrocnemius reflex was observed. 3. The inhibition by antidromic stimulation of the monosynaptic gastrocnemius reflex was significantly reduced. 4. During the early phases of local botulism an action of botulinum toxin on parts of the soma membrane of the alpha-motoneuron is suggested.

Action Potentials↗
PubMed1989

Molecular differences between type A botulinum neurotoxin and its toxoid.

The neurotoxins (seven serotypes, Mr approximately 150,000) produced by Clostridium botulinum cause the neuroparalytic disease botulism. Prophylaxis, definitive diagnosis and the only effective therapy for botulism depend, at present, on chemically detoxified form(s) of the neurotoxins, i.e. toxoids (immunogens), and the antisera raised with the immunogens. And yet, the toxoids currently used for immunization of humans and animals and for raising antibody are very crude preparations (approximately 90% impure) of the neurotoxins. Hence, the highly heterogenous toxoids were not suitable for physicochemical studies. We have detoxified a pure (greater than 99%) neurotoxin (serotype A) with formaldehyde. The native neurotoxin is composed of two subunit chains (Mr 53,000 and 97,000). The physicochemical properties of the toxoid (immunogenic in rabbits) were analyzed. The chemical modification produced inter- and intrasubunit covalent links at multiple sites and thus extensive aggregation of the neurotoxin. The secondary structure parameters (alpha-helix, beta-sheet, beta-turn and random coil) of the native protein were not significantly altered. Tertiary structure, as measured by exposure of tyrosine residues and fluorescence quantum yield of tryptophan residues, was considerably altered. The data imply that conformational (topographical) antigenic determinants may not contribute significantly to the serological property of the neurotoxin.

Botulinum Toxins↗
PubMed2006

Human milk SIgA binds to botulinum type B 16S toxin and limits toxin adherence on T84 cells.

Botulinum neurotoxin produced by Clostridium botulinum type B is in the form of a complex of 12S and 16S toxins. Food-borne botulism is caused by these complex toxins which are ingested orally and absorbed from the digestive tract. Here, we show that the human milk SIgA binds to the type B16S toxin. The binding of SIgA to 16S toxin and HA was inhibited by carbohydrates such as galactose, suggesting that the interaction of carbohydrate side chain of the SIgA with the HA of the 16S toxin is important for SIgA-16S complex formation. We also demonstrate that SIgA inhibits the attachment of 16S toxin to intestinal epithelial cells. These data suggest that the interaction of antigen nonspecific SIgA with 16S toxin has a large influence on the absorption of 16S toxin from the intestinal epithelium, and that SIgA may provide insight into developing a therapeutic agent for type B food-borne botulism.

Botulinum Toxins↗
PubMed2004

Small tripeptide surrogates with low nanomolar affinity as potent inhibitors of the botulinum neurotoxin B metallo-proteolytic activity.

Botulinum neurotoxin type B is a high-weight (150 kDa) protein produced by the anaerobic bacillus Clostridium botulinum. This metallo-protease neurotoxin cleaves synaptobrevin, a protein, which is crucial to neurotransmission, resulting in the muscle paralysis, which characterizes botulism. Inhibition of the metallo-peptidase activity is a possible approach to obtain specific therapeutics to treat botulism. We have previously reported a successful attempt to block the proteolytic activity of this neurotoxin with new, selective amino-thiol inhibitors endowed with Ki values in the 15-20 nanomolar range. With the aim of increasing the affinity and bioavailability of this first series of inhibitors we have optimized the residue that fits the P(1) subsite of the enzyme by comparing a series of ligands that contain subtle but significant variants of the parent structure. In addition, this strategy provided a simplification of the synthesis of BoNT/B inhibitors by reducing the possible number of stereoisomers. As such we were able to enhance the inhibitory potency whilst reducing the size as compared to the initial privileged structure yielding the first pseudo-tripeptide inhibitors with Ki values in the low nanomolar range.

Animals↗
PubMed2005

Molecular evolution of antibody affinity for sensitive detection of botulinum neurotoxin type A.

Botulism is caused by botulinum neurotoxin (BoNT), the most poisonous substance known. Potential use of BoNT as a biothreat agent has made development of sensitive assays for toxin detection and potent antitoxin for treatment of intoxication a high priority. To improve detection and treatment of botulism, molecular evolution and yeast display were used to increase the affinity of two neutralizing single chain Fv (scFv) antibodies binding BoNT serotype A (BoNT/A). Selection of yeast displayed scFv libraries was performed using methods to select for both increased association rate constant (k(on)) and decreased dissociation rate constants (k(off)). A single cycle of error prone mutagenesis increased the affinity of the 3D12 scFv 45-fold from a K(D) of 9.43x10(-10)M to a K(D) of 2.1x10(-11)M. Affinity of the HuC25 scFv was increased 37-fold from 8.44x10(-10)M to 2.26x10(-11)M using libraries constructed by both random and site directed mutagenesis. scFv variable region genes were used to construct IgG for use in detection assays and in vivo neutralization studies. While IgG had the same relative increases in affinity as scFv, (35-fold and 81-fold, respectively, for 3D12 and HuC25) higher solution equilibrium binding constants were observed for the IgG, with the 3D12 K(D) increasing from 6.07x10(-11)M to 1.71x10(-12)M and the HuC25 K(D) increasing from 4.51x10(-11)M to 5.54x10(-13)M. Affinity increased due to both an increase in k(on), as well as slowing of k(off). Higher affinity antibodies had increased sensitivity, allowing detection of BoNT/A at concentrations as low as 1x10(-13)M. The antibodies will also allow testing of the role of affinity in in vivo toxin neutralization and could lead to the generation of more potent antitoxin.

Antibody Affinity↗
PubMed2006

Fine and domain-level epitope mapping of botulinum neurotoxin type A neutralizing antibodies by yeast surface display.

Botulinum neurotoxin (BoNT), the most poisonous substance known, causes naturally occurring human disease (botulism) and is one of the top six biothreat agents. Botulism is treated with polyclonal antibodies produced in horses that are associated with a high incidence of systemic reactions. Human monoclonal antibodies (mAbs) are under development as a safer therapy. Identifying neutralizing epitopes on BoNTs is an important step in generating neutralizing mAbs, and has implications for vaccine development. Here, we show that the three domains of BoNT serotype A (BoNT/A) can be displayed on the surface of yeast and used to epitope map six mAbs to the toxin domains they bind. The use of yeast obviates the need to express and purify each domain, and it should prove possible to display domains of other BoNT subtypes and serotypes for epitope mapping. Using a library of yeast-displayed BoNT/A binding domain (H(C)) mutants and selecting for loss of binding, the fine epitopes of three neutralizing BoNT/A mAbs were identified. Two mAbs bind the C-terminal subdomain of H(C), with one binding near the toxin sialoganglioside binding site. The most potently neutralizing mAb binds the N-terminal subdomain of H(C), in an area not previously thought to be functionally important. Modeling the epitopes shows how all three mAbs could bind BoNT/A simultaneously and may explain, in part, the dramatic synergy observed on in vivo toxin neutralization when these antibodies are combined. The results demonstrate how yeast display can be used for domain-level and fine mapping of conformational BoNT antibody epitopes and the mapping results identify three neutralizing BoNT/A epitopes.

Antibodies, Bacterial↗
PubMed2006

Differential contribution of the residues in C-terminal half of the heavy chain of botulinum neurotoxin type B to its binding to the ganglioside GT1b and the synaptotagmin 2/GT1b complex.

Clostridium botulinum type B neurotoxin was effectively bound to synaptotagmin 2 (Stg2) associated with ganglioside GT1b, however, the molecular interaction between the neurotoxin and the Stg2/GT1b complex has not been identified. Previously, we found that infant botulism-related strain 111 generated a low activity of the neurotoxin (111/NT), which differed in some amino acid residues, especially in the carboxyl terminal half of the heavy chain (H(C)), from the original neurotoxin of strain Okra (Okra/NT) associated with a food-borne botulism. In this study, we evaluated the binding capabilities of site-directed mutants of Okra/H(C) to the Stg2/GT1b complex and to GT1b alone, and investigated the relationship between the toxic action and receptor binding. Replacement of K1187 and E1190 with glutamic acid and lysine, respectively, which substituted for the 111/NT residues, caused a reduction of binding affinity to the Stg2/GT1b complex, suggesting that both these residues contribute to the different binding affinity between Okra/NT and 111/NT. Substitution of four residues, H1240, S1259, W1261 and Y1262, which form a ganglioside pocket, drastically decreased the binding of H(C) to the Stg2/GT1b complex and to GT1b. Mutation in the residues, K1186, E1189, K1191 and K1260 reduced the binding of H(C) to GT1b alone, but not to the Stg2/GT1b complex. Analyses of effects of mutant toxins on toxicity of BoNT/B to cerebellar granule cells suggest the association of cell toxicity with binding to Stg2/GT1b complex but not that to GT1b alone.

Amino Acid Sequence↗
PubMed2004

Production and purification of a chimeric monoclonal antibody against botulinum neurotoxin serotype A.

Production of recombinant antibodies against botulinum neurotoxin is necessary for the development of a post-exposure treatment. CHO-DG44 cells were transfected with a plasmid encoding the light and heavy chains of a chimeric monoclonal antibody (S25) against botulism neurotoxin serotype A. Stable cell lines were obtained by dilution cloning and clones were shown to produce nearly equivalent levels of light and heavy chain antibody by an enzyme-linked immunosorbent assay (ELISA). In suspension culture, cells produced 35 microg/ml of chimeric antibody after 6 days, corresponding to a specific antibody productivity of 3.1 pg/cell/day. A method for the harvest and recovery of an antibody against botulism neurotoxin serotype A was investigated utilizing ethylenediamine-N,N'-tetra(methylphosphonic) acid (EDTPA) modified zirconia and MEP-hypercel, a hydrophobic charge interaction chromatography resin. Purification of the S25 antibody was compared to that achieved using rProtein A-Sepharose Fast Flow resin. After the direct load of culture supernatant, analysis by ELISA and gel electrophoresis showed that S25 antibody could be recovered at purities of 41 and 44%, from the EDTPA modified zirconia and MEP-hypercel columns, respectively. Although the purity obtained from each of these columns was low, the ability to withstand high column pressures and nearly 90% recovery of the antibody makes EDTPA modified zirconia well suited as an initial capture step. Combining the EDTPA modified zirconia and HCIC columns in series resulted in both purity and final product yield of 72%.

Animals↗
PubMed1995

Adsorption of botulinum toxin to activated charcoal with a mouse bioassay.

STUDY OBJECTIVE: We evaluated the effectiveness of activated charcoal (AC) in adsorbing Clostridium botulinum type A toxin using a mouse bioassay. DESIGN: Prospective, blinded, randomized, controlled animal study. SETTING: Animal care facility. PARTICIPANTS: One hundred forty Swiss/Webster ND-4 strain mice. INTERVENTION: Food contaminated with type A botulinum toxin was homogenized in a phosphate/gel buffer (pH 6.2). The concentrate was diluted by factors of 1:10, 1:50, and 1:100. AC was added to aliquots of the dilutions to a 20% final concentration. The samples were centrifuged, supernatant was removed, and separate groups of mice were injected intraperitoneally with .5 mL of each dilution (those treated with AC and controls untreated with AC). The animals were then observed over 5 days for signs of botulism. RESULTS: None of the 60 animals injected intraperitoneally with dilutions treated with AC was observed to have any signs of botulism. In contrast, deaths were observed in 10 of 20, 9 of 20 and 4 of 20 mice injected with untreated dilutions of 1:100, 1:50, and 1:10, respectively (P < .004). CONCLUSION: In this model, treatment of botulinum toxin with AC before administration resulted in greatly reduced morbidity and mortality.

Adsorption↗
PubMed1997

Approach to generalized weakness and peripheral neuromuscular disease.

A large number of intellectually engaging and potentially serious neuromuscular diseases have been presented. The emergency medicine physician must be able to recognize those entities that have the potential to clinically deterioration. The evaluation of weakness requires a comprehensive, broad-based differential that is driven by the history and physical. Diagnostic testing is determined by the clinical suspicion as is the urgency for further work-up. The following are the final diagnoses of the eight illustrative cases that were presented at the beginning of this article. Case 1. This unfortunate woman had a metabolic myopathy that was only diagnosed after enzymatic analysis of a muscle biopsy. Her genetic defect, carnitine palmitoyltransferase deficiency, is unusual as it does not present until late in adolescence or slightly later in life. It is a defect in lipid metabolism in which long-chain fatty acids are unable to gain entrance into the mitochondrion for oxidative degradation. The defect is apparent only after prolonged exercise or fasting. In this patient, rhabddomyolysis led to acute renal failure that resolved without requiring temporary dialysis. Case 2. This patient had an elevated CPK-MM. Her EMG showed myopathic changes and her nerve conduction studies were normal. She had a positive test for antinuclear antibodies. A biopsy of her quadriceps muscle revealed lymphocytic infiltration of the muscle fibers that showed some focal myocyte degeneration. The diagnosis of dermatomyositis was made based on the findings noted previously and the heliotrope hue of her periorbital skin. A search for an occult neoplasm was negative. She responded moderately to a course of high-dose prednisone. Case 3. The laboratory test that confirmed this diagnosis was the potassium of 2.4 mEq/L. The remainder of the electrolytes were normal. Infusion of 20 mEq of potassium over 2 hours led to a prompt return of normal muscle strength. The final diagnosis was hypokalemic periodic paralysis. In this disease there is an inherited defect in the ability of the myocyte to maintain a normal transmembrane potential. The defect is latent until there is a precipitating factor, such as an high carbohydrate meal or prolonged immobility. There is also a form seen with thyrotoxicosis and is essentially cured when the patient becomes euthyroid. The disease is seen most frequently in Asian males, although it is reported in most ethnic groups. Prophylaxis in these patients is with acetazolamide which raises the serum potassium indirectly by causing a metabolic acidosis. Triamterene and spironolactone have also been successfully used on occasion. This patient turned out to have thyrotoxicosis as well. Case 4. This man had both cranial motor and peripheral muscular dysfunction. There was no evidence of nonmotor cranial nerve dysfunction, nor was there evidence of any peripheral sensory deficits. The diagnosis of myasthenia gravis was established by the rapid and transient response of this patient to 2 mg of edrophonium. He was found to have antiacetylcholine receptor antibodies and was also thyrotoxic. He had a stormy course requiring intubation and prolonged ventilation. Eventually, he underwent thymectomy and is stable on pyridostigmine. Case 5. Initially suspected to be hysteria, this patient and his relatives had botulism from home-canned peppers. The index case required prolonged intubation and ventilation. The patients were treated with polyvalent antiserum and gastric lavage to remove the residual contaminated food which was still in their stomachs due to the gastric atony seen with this disease. The botulinus toxin prevents the release of acetylcholine molecules from their storage vesicles in nerve terminals. Thus, this disease is the opposite of the cholinergic syndrome seen with organophosphate insecticide poisonings except that cognitive functioning is not impaired in botulism. Case 6. This is a celebrated case that took a great deal of sleuthing

Adult↗
PubMed2004

Development of botulinum toxin therapy.

Justinius Kerner collected data on 230 cases of botulism in the 1820s, suggested the therapeutic use of toxin, and gave a remarkably complete and accurate description of clinical botulism: its symptoms, time course, and the physical findings that the tear fluid disappears, the skin is dry, the eye, gut, and somatic muscles are paralyzed, and mucus and saliva secretion is suppressed. These effects are the clinical targets of botulinum therapy today. Inspired by Drachman's use of toxin to safely paralyze the hind limb in chicks, we worked out the procedures for its safe medical application and licensure from 1972 to 1989, applying it first to correct strabismus, blepharospasm, leg muscle spasm, and torticollis. This list is now extended by others to well over 100 uses. For many years, blepharospasm patients returning for injection around the eyes and upper face would mention as a joke that they were "back to get the wrinkles out." Working in aesthetic dermatology and ophthalmology, Alistair and Jean Carruthers could envision the intentional cosmetic application of botulinum toxin, probably its greatest single use today.

Botulinum Toxins, Type A↗
PubMed2003

Thio-derived disulfides as potent inhibitors of botulinum neurotoxin type B: implications for zinc interaction.

Botulinum neurotoxin type B causes the inhibition of acetylcholine release at the neuromuscular junction resulting in a flaccid paralysis designated botulism. This occurs through the cleavage of synaptobrevin, an intracellular critical component of neurotransmitter exocytosis, by the zinc-metallopeptidase activity of the smallest subunit of the toxin. Blocking the proteolytic activity may present an attractive approach to treat botulism as to date there is no efficient specific drug therapy available. We have therefore recently described a series of beta-amino-thiol derived pseudotripeptides able of inhibiting the toxin at low (10(-8) M) concentration. In this study, binding characteristics of the protein's active site are explored through various structural modifications of the thiol functionality which was supposed to be a key structural constituent for effective zinc-ion chelation. Surprisingly, sulfanyl-derivatives such as symmetric disulfides were shown to be better inhibitors than their thiol-counterparts, the most potent compound displaying a Ki value of 3.4 nM.

Binding Sites↗
PubMed2003

Honey consumption in the state of São Paulo: a risk to human health?

Infantile botulism was recognized in 1976 as a paralyzing disease caused by the ingestion of viable spores that would germinate and colonize the intestinal tract of infants, with local production and absorption of Clostridium botulinum toxin. The possible origins of botulinic spores are dust and honey, which has been identified as a dietary risk factor for infantile botulism. The objectives of the present study were to investigate 100 honey samples obtained in the state of São Paulo (Brazil) in terms of incidence of botulinic spores and of microbiologic quality, in agreement with Decree 367/9. All 100 samples analysed were negative for the presence of Salmonella, Shigella, total coliforms. C. botulinum spores were present in 3 samples (3%) and molds and yeasts, in 64 samples (64%), but only 25 (25%) exceeded established criteria, with counts ranging from zero to 1.5 x 10(5)CFU/g. The presence of small sporogenic Gram-positive rods was observed in 42 (42%) of the 100 samples tested but these bacteria were not identified.

Journal Article↗