SNARE motif and neurotoxins.
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Amino Acid Sequence↗
Biomedical subjects
C Montecucco
Publications and source records attributed to C Montecucco.
Cellular vacuoles induced by Helicobacter pylori originate from late endosomal compartments.
Pathogenic strains of Helicobacter pylori cause progressive vacuolation and death of epithelial cells. To identify the nature of vacuoles, the distribution of markers of various membrane traffic compartments was studied. Vacuoles derive from the endocytic pathway since they include the fluid-phase marker Lucifer yellow. Early endosome markers such as rab5, transferrin, and transferrin receptor, as well as the lysosomal hydrolase cathepsin D, are excluded from these structures. In contrast, the vacuolar membrane is specifically stained by affinity-purified antibodies against rab7, a small GTPase, localized to late endosomal compartments. The labeling of rab7 on vacuolar membranes increases as vacuolation progresses, without a concomitant increase of cellular rab7. Cell vacuolation is inhibited by the microtubule-depolymerizing agents nocodazole and colchicine. Taken together, these findings indicate that the vacuoles specifically originate from late endosomal compartments.
Adenine↗
Autoantibodies to human nuclear lamin B2 protein. Epitope specificity in different autoimmune diseases.
The nuclear lamina of mammalian cells consists of three major proteins, lamins A, C, and B, and a fourth minor protein, lamin B2. Lamins belong to the family of intermediate filaments and are highly similar both in structure and primary sequence. They are organized in three well-defined domains: 1) a central alpha-helical rod, which is a secondary structure shared by all types of intermediate filaments, formed by three alpha-helices (coils 1A, 1B, and 2) and surrounded by 2) an amino-terminal head and 3) a carboxyl-terminal tail. Autoantibodies toward major lamin have been described previously in sera from patients with different autoimmune diseases. We chose an epitope mapping approach to further characterize the autoimmune response to nuclear lamin. Different lamin B2 domains were expressed as fusion proteins with the glutathione S-transferase and then used in immunoblotting experiments to analyze sera from patients with autoimmune diseases (chronic active hepatitis, SLE, rheumatoid arthritis, and polymyalgia rheumatica) and from healthy subjects. At a 1:1000 dilution, none of the control sera recognized any of the recombinant polypeptides. Conversely, reactive sera were present in all groups of patients. The ability to recognize a protein domain seemed to differ with the pathology. Most chronic active hepatitis sera were reactive to two or more lamin domains and reacting SLE sera always gave positive signals to coil 2 and/or coil 1B. Coil 2 was preferentially recognized by rheumatoid arthritis sera. Polymyalgia rheumatica sera differed from all of the others because of their low reactivity to the rod domain and preference for the C terminus, a lamin-specific domain.
Autoantibodies↗
Botulinum G neurotoxin cleaves VAMP/synaptobrevin at a single Ala-Ala peptide bond.
Similarly to other serotypes, botulinum neurotoxin serotype G (BoNT/G) contains the zinc binding motif of zinc endopeptidases. Highly purified preparations of BoNT/G show a zinc-dependent protease activity specific for VAMP/synaptobrevin, a membrane protein of synaptic vesicles. The two neuronal VAMP isoforms are cleaved with similar rates at one Ala-Ala peptide bond present in the same region, out of the several such peptide bonds present in their sequences. This site of cleavage is unique among the eight clostridial neurotoxins. VAMP proteolysis is displayed only after reduction of the single interchain disulfide bond present in the toxin, and it is inhibited by EDTA, o-phenanthroline and captopril.
Alanine↗
Bacterial protein toxins penetrate cells via a four-step mechanism.
Bacteria produce several protein toxins that act inside cells. These toxins bind with high affinity to glycolipid or glycoprotein receptors present on the cell surface. Binding is followed by endocytosis and intracellular trafficking inside vesicles. Different toxins enter different intracellular routes, but have the common remarkable property of being able to translocate their catalytic subunit across a membrane into the cytosol. Here, a toxin modifies a specific target with ensuing cell alterations, necessary for the survival and diffusion strategies of the toxin producing bacterium.
Bacterial Toxins↗
Study of prognosis in Waldenström's macroglobulinemia: a proposal for a simple binary classification with clinical and investigational utility.
Prognostic evaluation of Waldenström's macroglobulinemia (WM) is unreliable, few studies considered prognostic factors in WM and only one was derived from a multivariate analysis. One hundred forty-four retrospective, previously untreated patients with clinically overt WM were studied to learn whether overall survival was related to any of the various clinical features presented at diagnosis. Patients were homogeneously treated with intermittent doses of chlorambucil for as long as this showed an effect on the monoclonal component. The population was randomly subdivided into a 90-patient exploratory sample, on whom investigation would be conducted, and in a 54-patient test sample, on whom the results would be validated. In the exploratory sample univariate analysis identified the following parameters as the most important for prognosis: age (< or > or = 70 years), platelet count (< or > or = 120 x 10(9)/L), presence or absence of an abnormal number of red blood cells in the urine, hemoglobin concentration (< or > or = 9 g/dL), erythrocyte sedimentation rate (< or > or = 110 mm at first hour), presence or absence of cryoglobulinemia and of weight loss. Cox multivariate analysis showed that only hemoglobin, age, weight loss, and cryoglobulinemia independently affected survival. These four clinical variables were also shown to be able to discriminate survival significantly in the test sample. Moreover, it was possible to demonstrate (both in the exploratory and the test sample) that clear-cut, albeit dichotomic, survival discrimination can be reached with the presence at diagnosis of either no more than one, or any two or more, of these four prognosticators. These simple clinical criteria could be the basis of an initial binary, prognostic classification of WM, which could help in differentiating therapy according to the severity of the disease, and in properly designing future clinical trials.
Adult↗
Tetanus and botulinum neurotoxins are zinc proteases specific for components of the neuroexocytosis apparatus.
Tetanus and botulinum neurotoxins bind to nerve cells, penetrate the cytosol, and block neurotransmitter release. Comparison of their amino-acid sequences shows the presence of the highly conserved His-Glu-x-x-His zinc-binding motif of zinc-endopeptidases (HExxH). Atomic absorption measurements of clostridial neurotoxins show the presence of one atom of zinc/toxin molecule bound to the light chain. The toxin-bound zinc ion is essential for the neurotoxins inhibition of neurotransmitter release in Aplysia neurons injected with the toxins. Phosphoramidon, a very specific inhibitor of zinc-endopeptidases, blocks the intracellular activity of the clostridial neurotoxins. Highly purified preparations of the light chain of tetanus and botulinum B and F neurotoxins cleaved specifically VAMP/synaptobrevin, an integral membrane protein of small synaptic vesicles, both in vivo and in vitro. From these studies, it can be concluded that the clostridial neurotoxins responsible for tetanus and botulism block neuroexocytosis via the proteolytic cleavage of specific components of the neuroexocytotic machinery.
Amino Acid Sequence↗
Anticardiolipin antibodies in pediatric systemic lupus erythematosus.
OBJECTIVE: To investigate the prevalence and the clinical significance of anticardiolipin antibodies (ACLs) in a group of children with systemic lupus erythematosus (SLE). DESIGN: Cross-sectional and longitudinal study. SETTING: Pediatric Clinic, University of Pavia, Italy. PARTICIPANTS: Thirty children (aged 4.9 to 16.5 years) with SLE. MEASUREMENTS AND MAIN RESULTS: Twenty-six (87%) of the 30 patients were initially positive for either IgG or IgM ACLs; 24 (80%) of 30 had IgG ACLs, and 15 (50%) of 30 had IgM ACLs. The cross-sectional analysis showed a trend for IgG ACLs to be positively associated with autoimmune cytopenia and negatively associated with renal disease. The levels of ACLs, particularly of the IgG isotype, tended to correlate with SLE activity as expressed by the complement fraction C3, the erythrocyte sedimentation rate, or the SLE Activity Measure, but not by the SLE Disease Activity Index or the anti-DNA antibodies. Serial determinations of ACL levels in 20 patients revealed frequent fluctuations. High levels of IgG ACLs (> 50 arbitrary units) were observed in nine patients; all nine had active disease and eight had one or more clinical features that have been previously associated with antiphospholipid antibodies: neuropsychiatric manifestations in six patients, autoimmune cytopenia in two patients, and avascular necrosis of bone in one patient. Only one patient experienced an overt episode of vascular thrombosis; IgG ACLs were positive at a medium level 6 months before the thrombotic event, but their level was unchanged when the thrombosis was discovered; the lupus anticoagulant test was positive at time of the thrombosis. CONCLUSIONS: Our results show that in pediatric SLE, ACLs are frequently found, high levels of IgG ACLs are often associated with central nervous system involvement, and ACLs have a low predictive value in the development of vascular thrombosis.
Adolescent↗
Allopurinol mouthwashes in methotrexate-induced stomatitis.
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Aged↗
Clostridial neurotoxins as tools to investigate the molecular events of neurotransmitter release.
The clostridial neurotoxins responsible for tetanus and botulism are eight different proteins, composed of two disulfide-linked polypeptide chains. They bind specifically to the presynaptic membrane via the heavy chain, while the light chain enters the cytosol of the neurons, where it displays a zinc-endopeptidase activity directed to proteins of the neuroexocytosis apparatus. Tetanus neurotoxin and botulinum neurotoxin serotypes B, D, F and G cleave specifically and at single different peptide bonds VAMP/synaptobrevin, a component of small synaptic vesicles. In contrast, the other neurotoxins catalyze the hydrolysis of proteins of the presynaptic membrane. Serotypes A and E of botulinum neurotoxin cleave SNAP-25, at different sites located within the carboxyl-terminus, while the specific target of serotype C is syntaxin.
Animals↗
Molecular mechanisms of action of bacterial protein toxins.
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Amino Acid Sequence↗
Unravelling the pathogenic role of Helicobacter pylori in peptic ulcer: potential new therapies and vaccines.
The recognition that peptic ulcer is an infectious disease caused by the bacterium Helicobacter pylori has revolutionized the approach to diagnosis and therapy of this condition. Treatment of the symptoms of peptic ulcer with drugs that block acid secretion is already being replaced by antibiotic eradication of the causative agent. Studies of the molecular events that lead to H. pylori pathogenesis have shown that clinical isolates can be divided into two groups, only one of which produces a cytotoxin and is associated with severe disease. The cloning of the genes coding for molecules specific for disease-associated strains of H. pylori, and the development of animal models that mimic the human pathology, will provide the basis for better strategies to treat and prevent peptic-ulcer disease.
Animals↗
Eurotox-6 conference: old bacterial toxins reveal new cell machineries.
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Bacterial Physiological Phenomena↗
Mechanism of action of tetanus and botulinum neurotoxins.
The clostridial neurotoxins responsible for tetanus and botulism are metallo-proteases that enter nerve cells and block neurotransmitter release via zinc-dependent cleavage of protein components of the neuroexocytosis apparatus. Tetanus neurotoxin (TeNT) binds to the presynaptic membrane of the neuromuscular junction and is internalized and transported retroaxonally to the spinal cord. Whilst TeNT causes spastic paralysis by acting on the spinal inhibitory interneurons, the seven serotypes of botulinum neurotoxins (BoNT) induce a flaccid paralysis because they intoxicate the neuromuscular junction. TeNT and BoNT serotypes B, D, F and G specifically cleave VAMP/synaptobrevin, a membrane protein of small synaptic vesicles, at different single peptide bonds. Proteins of the presynaptic membrane are specifically attacked by the other BoNTs: serotypes A and E cleave SNAP-25 at two different sites located within the carboxyl terminus, whereas the specific target of serotype C is syntaxin.
Amino Acid Sequence↗
Long term treatment of polymyalgia rheumatica with deflazacort.
OBJECTIVES: To evaluate the long term efficacy and tolerability of deflazacort, a corticosteroid reputed to have only minor side effects, in the treatment of polymyalgia rheumatica (PMR). METHODS: In a prospective open study, deflazacort was administered at an average initial dose of 21.8 mg/day for a mean period of 19 months in 40 patients with PMR. RESULTS: A highly significant improvement of clinical and laboratory parameters occurred one month after therapy onset. This improvement persisted for the whole study period. Laboratory parameters of tolerability did not change during the study. Mild to moderate steroid-related side effects occurred in 57.9% of the patients. CONCLUSIONS: Deflazacort is effective in the treatment of PMR. Its long term safety profile may be superior to that of other corticosteroids.
Aged↗
Tidal irrigation in Milwaukee shoulder syndrome.
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Aged↗
[FDDF (fast dissolving dosage form) piroxicam for sublingual administration in the treatment of rheumatoid arthritis].
Open non-comparative study for the evaluation of the efficacy and tolerance of piroxicam FDDF for sublingual administration in the treatment of rheumatoid arthritis. Thirty patients (6 males and 24 females) suffering from rheumatoid arthritis in the active phase have been treated. All the patients had to fulfil the criteria for the rheumatoid arthritis classification proposed by the American Rheumatism Association (ARA). The efficacy of therapy has been evaluated, after 2, 4 and 6 week of treatment, through the changes in: the number of painful or tender joints on motion, the number of swollen joints, grip strength, ESR. Also day pain, night pain, duration of morning stiffness and functional index have been evaluated. As regards the functional index, activities as dressing, arising, eating, walking, taking care of hygiene, bending, standing and sitting have been considered. The study sample was composed by 30 patients, with a mean age of 59.73 years, suffering from rheumatoid arthritis from 4.76 years. As regards efficacy parameters, day pain, which is recorded on a 21 compartment visual analogue scale, was initially of 8.13 (+/- 3.73), and after 2 weeks of therapy decreased of about 1 point and after 4 weeks was of 6.57 (+/- 3.73). This improvement was already statistically significant at the first control (p = 0.01). At the first control also morning stiffness resulted improved in a statistically significant way (p < 0.0001). As regards functional index a statistically significant improvement was observed in the disability of walking and of picking up objects after 2 weeks; after 4 weeks a significant improvement was observed in the disability of arising and of bending. These changes in functional ability probably depend upon the kind of joint involved and the duration of these lesions. Also the grip strength resulted statistically improved at the 2 control. As regards objective values, there was a statistically significant improvement in tender and swollen joints after only 2 weeks. As regards ESR, which is an index of disease activity, was initially of 40.73 (+/- 16.75) in mean; at the end of the 6th week it was of 34.72 (+/- 15.13): this reduction was statistically significant. No improvement was observed in night pain, normally the pain form which is more difficult to cure. As regards toleration, only 2 patients reported side-effects: the first reported epigastralgia and the second oral burning Both side-effects lasted 1 day and, according to the physician, their relation with the study drug is not sure.(ABSTRACT TRUNCATED AT 400 WORDS)
Administration, Sublingual↗
Role of ANCA in the pathogenesis of Wegener's granulomatosis: a short review.
The presence of autoantibodies to neutrophil cytoplasmic proteinase-3, usually reported as c-ANCA, is virtually diagnostic for Wegener's granulomatosis and related conditions. These antibodies are highly associated with active systemic disease, and may be implicated in pathogenesis. In vitro, c-ANCA can induce a respiratory burst and degranulation of cytokine-primed neutrophils, leading to lysis of cultured endothelial cells. This and other putative pathogenic mechanisms are reviewed.
Antibodies, Antineutrophil Cytoplasmic↗