Differential effects of staphylococcal toxic shock syndrome toxin-1 on B cell apoptosis.

Superantigens, such as toxic shock syndrome toxin 1 (TSST-1), have been implicated in the pathogenesis of several autoimmune and allergic diseases associated with polyclonal B cell activation. In this report, we studied the in vitro effects of TSST-1 on B cell activation. We show herein that TSST-1 produced antagonistic effects on Ig synthesis by peripheral blood mononuclear cells (PBMC) from normal subjects, depending on the concentration used; Ig production was inhibited at 1000 pg/ml (P < 0.01) and enhanced at 1 and 0.01 pg/ml (P < 0.01) of toxin. Cultures of PBMC were then examined for morphologic features and DNA fragmentation characteristic for apoptosis. B cells exhibited a significantly higher (P < 0.01) incidence of apoptosis after stimulation with 1000 pg/ml of TSST-1 compared with 1 or 0.01 pg/ml of toxin or medium alone. Abundant expression of Fas, a cell surface protein that mediates apoptosis, was detected on B cells after stimulation with 1000 pg/ml of TSST-1 and was significantly higher on B cells undergoing apoptosis than on live cells (P = 0.01). Additionally, increased Fas expression and B cell death occurred at concentrations of TSST-1 inducing the production of high amounts of gamma interferon (IFN-gamma), and both events could be blocked by neutralizing anti-IFN-gamma antibody. These findings suggest that high concentrations of TSST-1 can induce IFN-gamma-dependent B cell apoptosis, whereas at low concentrations it stimulates Ig synthesis by PBMC from normal subjects. These findings support the concept that staphylococcal toxins have a role in B cell hyperactivity in autoimmunity and allergy.

Transcytosis of cholera toxin subunits across model human intestinal epithelia.

Cholera toxin (CT) elicits a massive secretory response from intestinal epithelia by binding apical receptors (ganglioside GM1) and ultimately activating basolateral effectors (adenylate cyclase). The mechanism of signal transduction from apical to basolateral membrane, however, remains undefined. We have previously shown that CT action on the polarized human intestinal epithelial cell line T84 requires endocytosis and processing in multiple intracellular compartments. Our aim in the present study was to test the hypothesis that CT may actually move to its site of action on the basolateral membrane by vesicular traffic. After binding apical receptors, CT entered basolaterally directed transcytotic vesicles. Both CT B subunits and to a lesser extent CT A subunits were delivered intact to the serosal surface of the basolateral membrane. The toxin did not traverse the monolayer by diffusion through intercellular junctions. Transcytosis of CT B subunits displayed nearly identical time course and temperature dependency with that of CT-induced Cl- secretion--suggesting the two may be related. These data identify a mechanism that may explain the link between the toxin's apical receptor and basolateral effector.

Transgenic mice carrying the diphtheria toxin A chain gene under the control of the granzyme A promoter: expected depletion of cytotoxic cells and unexpected depletion of CD8 T cells.

We have generated transgenic mice bearing the diphtheria toxin A chain (DTA) gene under the control of granzyme A (GrA) promoter sequences (GrA-DTA). GrA is expressed in activated cytotoxic cells but not in their immediate progenitors. These GrA-DTA mice are deficient in cytotoxic functions, indicating that most cytotoxic cells express GrA in vivo. Surprisingly, one founder strain containing a multicopy GrA-DTA insert show a marked and selective deficiency in CD8+ cells in peripheral lymphoid organs. This depletion was not observed in thymus, where the distribution of CD4+ and CD8+ cells is normal. Moreover, the emigration of T cells from thymus is normal, indicating that the depletion occurs in the periphery. GrA-DTA mice should be useful as models to dissect the role of cytotoxic cells in immune responses and as recipients of normal and neoplastic hematopoietic cells. The selective depletion of CD8+ cells in one founder strain could have implications for postthymic T-cell development.

A trace component of ginseng that inhibits Ca2+ channels through a pertussis toxin-sensitive G protein.

A crude extract from ginseng root inhibits high-threshold, voltage-dependent Ca2+ channels through an unknown receptor linked to a pertussis toxin-sensitive G protein. We now have found the particular compound that seems responsible for the effect: it is a saponin, called ginsenoside Rf (Rf), that is present in only trace amounts within ginseng. At saturating concentrations, Rf rapidly and reversibly inhibits N-type, and other high-threshold, Ca2+ channels in rat sensory neurons to the same degree as a maximal dose of opioids. The effect is dose-dependent (half-maximal inhibition: 40 microM) and it is virtually eliminated by pretreatment of the neurons with pertussis toxin, an inhibitor of G(o) and Gi GTP-binding proteins. Other ginseng saponins--ginsenosides Rb1, Rc, Re, and Rg1--caused relatively little inhibition of Ca2+ channels, and lipophilic components of ginseng root had no effect. Antagonists of a variety of neurotransmitter receptors that inhibit Ca2+ channels fail to alter the effect of Rf, raising the possibility that Rf acts through another G protein-linked receptor. Rf also inhibits Ca2+ channels in the hybrid F-11 cell line, which might, therefore, be useful for molecular characterization of the putative receptor for Rf. Because it is not a peptide and it shares important cellular and molecular targets with opioids, Rf might be useful in itself or as a template for designing additional modulators of neuronal Ca2+ channels.

Toxin-induced pore formation is hindered by intermolecular hydrogen bonding in sphingomyelin bilayers

Sticholysin I and II (StnI and StnII) are pore-forming toxins that use sphingomyelin (SM) for membrane binding. We examined how hydrogen bonding among membrane SMs affected the StnI- and StnII-induced pore formation process, resulting in bilayer permeabilization. We compared toxin-induced permeabilization in bilayers containing either SM or dihydro-SM (lacking the trans 4 double bond of the long-chain base), since their hydrogen-bonding properties are known to differ greatly. We observed that whereas both StnI and StnII formed pores in unilamellar vesicles containing palmitoyl-SM or oleoyl-SM, the toxins failed to similarly form pores in vesicles prepared from dihydro-PSM or dihydro-OSM. In supported bilayers containing OSM, StnII bound efficiently, as determined by surface plasmon resonance. However, StnII binding to supported bilayers prepared from dihydro-OSM was very low under similar experimental conditions. The association of the positively charged StnII (at pH 7.0) with unilamellar vesicles prepared from OSM led to a concentration-dependent increase in vesicle charge, as determined from zeta-potential measurements. With dihydro-OSM vesicles, a similar response was not observed. Benzyl alcohol, which is a small hydrogen-bonding compound with affinity to lipid bilayer interfaces, strongly facilitated StnII-induced pore formation in dihydro-OSM bilayers, suggesting that hydrogen bonding in the interfacial region originally prevented StnII from membrane binding and pore formation. We conclude that interfacial hydrogen bonding was able to affect the membrane association of StnI- and StnII, and hence their pore forming capacity. Our results suggest that other types of protein interactions in bilayers may also be affected by hydrogen-bonding origination from SMs.

Botulinum Toxin as an Alternative to Treat the Spasm of the Near Reflex

We describe the case of an eight-year-old girl with complaints of headaches and blurred vision (uncorrected visual acuity: 0.1 decimal) that showed on examination miotic pupils, pseudomyopia, no ocular motility restrictions, and no associated neurological disease. After initial treatment with cyclopentolate for two months, pseudomyopia persisted with an intermittent and variable esotropia. Spectacles of +1 both eyes and atropine 1% one drop daily were then prescribed. The situation improved and remained stable for several weeks, with pseudomyopia and esotropia reappearing later. Finally, botulinum toxin (2.5 iu Botox®) was injected in the medial rectus muscle on two occasions and a visual therapy program based on the stimulation of fusional divergence, diplopia, and stereopsis consciousness was recommended. This prescription was combined with the use of atropine during the first few weeks. Orthotropia and corrected distance visual acuity of 1.0 were found three months after treatment. The evolution and clinical results of this case report suggest that botulinum toxin in combination with other therapeutic alternatives may be useful in the treatment of spasm of the near reflex.

Real cedula de S.M. y señores del consejo, por la qual se manda cese la observancia de la instrucción adicional de 16 de noviembre de 1786, y que se guarden y tengan entero cumplimiento todas las anteriores reales resoluciones, que gobernaban en el ramo de propios y arbitrios del reyno, destinandose los sobrantes de estos efectos á la extincion y recogimiento de los vales reales, bajo las reglas que se expresan.

Certifica la copia Pedro Escolano de Arrieta.

A study of the effect of ionizing radiation on resistance, germination, and toxin synthesis of Clostridium botulinum spores, types A, B, and E

At head of title: The University of Michigan, College of Engineering, Dept. of Chemical and Metallurgical Engineering. Final report.

Real cedula de S.M. y señores del Consejo por la que se manda cese la observancia de la Instrucción adicional de 16 de noviembre de 1786, y que se guarden y tengan entero cumplimiento todas las anteriores reales resoluciones, que gobernaban en el ramo de propios y arbitrios del Reyno, destinandose los sobrantes de estos efectos á la extinción y recogimiento de los Vales Reales, bajo las reglas que se expresan

Certifica la copia Pedro Escolano de Arrieta.

Defense against toxin weapons /

Mode of access: Internet.

Infectious entero-hepatitis (blackhead) in turkeys.

This essay was awarded the Poultry Disease Essay Prize for 1947.

Getting muscles moving again after botulinum toxin: novel therapeutic challenges

The use of botulinum neurotoxins for the treatment of muscle hyperactivity and spasticity disorders has been remarkably successful, owing to the abilities of the toxins to elicit prolonged localized paralysis and the rarity of serious adverse effects. However, botulinum toxins are the most deadly protein toxins known, and existing antidotes possess limited effectiveness. Paradoxically, in situ, the intoxicated motoneuron does not die. It reacts by emanating a sprouting network known to implement new functional synapses, leading to resumption of neurotransmission. Recent studies have highlighted ways of accelerating this natural recovery process to overcome paralysis successfully. Developing new therapeutic strategies and treatments for botulism will require more research into the molecular understanding of this 'naturally occurring' recovery process.