Adult zebrafish intestine resection: a novel model of short bowel syndrome, adaptation, and intestinal stem cell regeneration.

Loss of significant intestinal length from congenital anomaly or disease may lead to short bowel syndrome (SBS); intestinal failure may be partially offset by a gain in epithelial surface area, termed adaptation. Current in vivo models of SBS are costly and technically challenging. Operative times and survival rates have slowed extension to transgenic models. We created a new reproducible in vivo model of SBS in zebrafish, a tractable vertebrate model, to facilitate investigation of the mechanisms of intestinal adaptation. Proximal intestinal diversion at segment 1 (S1, equivalent to jejunum) was performed in adult male zebrafish. SBS fish emptied distal intestinal contents via stoma as in the human disease. After 2 wk, S1 was dilated compared with controls and villus ridges had increased complexity, contributing to greater villus epithelial perimeter. The number of intervillus pockets, the intestinal stem cell zone of the zebrafish increased and contained a higher number of bromodeoxyuridine (BrdU)-labeled cells after 2 wk of SBS. Egf receptor and a subset of its ligands, also drivers of adaptation, were upregulated in SBS fish. Igf has been reported as a driver of intestinal adaptation in other animal models, and SBS fish exposed to a pharmacological inhibitor of the Igf receptor failed to demonstrate signs of intestinal adaptation, such as increased inner epithelial perimeter and BrdU incorporation. We describe a technically feasible model of human SBS in the zebrafish, a faster and less expensive tool to investigate intestinal stem cell plasticity as well as the mechanisms that drive intestinal adaptation.

High-affinity, protective antibodies to the binding domain of botulinum neurotoxin type A.

Monoclonal antibodies (MAbs) were prepared against the putative binding domain of botulinum neurotoxin A (BoNT/A), a nontoxic 50-kDa fragment. Initially, all fusion products were screened against the holotoxin BoNT/A and against the binding fragment, BoNT/A H(C). Eleven neutralizing hybridomas were cloned, and their specific binding to BoNT/A H(C) was demonstrated by surface plasmon resonance, with dissociation constants ranging from 0.9 to <0.06 nM. Epitope mapping by real-time surface plasmon resonance showed that the antibodies bound to at least two distinct regions of the BoNT/A H(C) fragment. These MAbs will be useful tools for studying BoNT/A interactions with its receptor, and they have potential diagnostic and therapeutic applications.

Identifying the principal protective antigenic determinants of type A botulinum neurotoxin.

The neurotoxins from Clostridium botulinum (BoNT serotypes A-G) exert their lethal effect by preventing the release of acetylcholine at the neuromuscular junction. As with tetanus toxin, immunization with a non-toxic fragment, the 50 kDa C-terminal portion of BoNT/A (Hc; residues 861-1296), protects mice against lethal challenges with the intact toxin. To locate the neutralizing epitopes, several protective monoclonal antibodies (mAbs) against BoNT/A-Hc were isolated and cloned. Specific binding of the mAbs to BoNT/A-Hc was demonstrated by surface plasmon resonance, with Kas in the range of 10(-10) to 10(-11) M. These antibodies recognized a genetically engineered polypeptide (1150-1289) that was previously shown to induce protective immunity. Prior to the determination of the X-ray crystal structure of the tetanus neurotoxin Hc fragment, molecular modelling studies indicated that it contained two highly solvent-exposed loops. Based on these predictions, two 25-mer Hc-peptides corresponding to these two regions were synthesized and were demonstrated to bind the neutralizing mAbs. Mice immunized with the Hc-peptides had high levels of antibodies that recognized BoNT/A-Hc. However, immunizations with only one of the Hc peptides protected when mice were challenged with BoNT/A. On the basis of these analyses, it should be possible to develop small peptides that could be useful in the design of future vaccines against these neurotoxins.

A perversion named desire.

Inspired by the title of the work, A Streetcar Named Desire by Tennessee Williams, the author argues that desire and perversion are equivalent, based on the following. (1) The notion of infanatile sexuality as polymorphously perverse, and whose components constitute the 'core of our unconscious' and the ultimate 'matter' of unconscious desire. (2) The perspective of narcissism, which establishes desire, supported by the theory that maternity implants an illusion of completeness which culture promotes, despite the fact that such an ideal conflicts with the laws governing the foundation of culture. (3) The resulting forms of the oedipal complex and the castration complex, whether man or woman, imply a visible or unapparent violence with regard to the original 'call' of desire. (4) The traditional structures refer to the possibility of the mother imagining herself as completed by the child: the blocking of that illusion is associated with psychosis; the weakness of the desire, once established, demands, in the context of perversion, the presence of the figure of plenitude. Neurosis prefers its absence on the level of the apparent while insuring its permanence on the unconscious level.

From the analysis of a perversion.

The coexistence of physical malformation and homosexuality and their mutual effects on each other are examined in the context of an account of the early months of an analysis. The material is structured around the hypothesis that this perversion is based on the existence of a perverse pact between the mother and the son, characterized specifically by a particular exchange of disavowals: the typical attribution by the child of phallic completeness to the mother is returned by her in her transformation by disavowal of the son's physical deformity into an image of beautiful fullness and physical normality. The material is set out and developed with a view to corroborating this hypothesis in detail; this account is followed by a brief review of the concepts of narcissism, disavowal and splitting of the ego, which constitute the Freudian theoretical basis for an understanding of the case. Narcissism is observed here from the point of view of the fusion of mother and son and the vicissitudes and difficulties of separation. Disavowal is examined from three aspects: repudiation of the absence of a penis in the mother, of the father's function and of the physical malformation.