Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects

Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German 'Federal Institute for Risk Assessment' hosted an 'International Workshop on Contact Dermatitis'. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15-20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed.     

Human body temperature and new approaches to constructing temperature-sensitive bacterial vaccines

Many of the live human and animal vaccines that are currently in use are attenuated by virtue of their temperature-sensitive (TS) replication. These vaccines are able to function because they can take advantage of sites in mammalian bodies that are cooler than the core temperature, where TS vaccines fail to replicate. In this article, we discuss the distribution of temperature in the human body, and relate how the temperature differential can be exploited for designing and using TS vaccines. We also examine how one of the coolest organs of the body, the skin, contains antigen-processing cells that can be targeted to provoke the desired immune response from a TS vaccine. We describe traditional approaches to making TS vaccines, and highlight new information and technologies that are being used to create a new generation of engineered TS vaccines. We pay particular attention to the recently described technology of substituting essential genes from Arctic bacteria for their homologues in mammalian pathogens as a way of creating TS vaccines.     

Evidence for lateral gene transfer between Archaea and bacteria from genome sequence of Thermotoga maritima.

The 1,860,725-base-pair genome of Thermotoga maritima MSB8 contains 1,877 predicted coding regions, 1,014 (54%) of which have functional assignments and 863 (46%) of which are of unknown function. Genome analysis reveals numerous pathways involved in degradation of sugars and plant polysaccharides, and 108 genes that have orthologues only in the genomes of other thermophilic Eubacteria and Archaea. Of the Eubacteria sequenced to date, T. maritima has the highest percentage (24%) of genes that are most similar to archaeal genes. Eighty-one archaeal-like genes are clustered in 15 regions of the T. maritima genome that range in size from 4 to 20 kilobases. Conservation of gene order between T. maritima and Archaea in many of the clustered regions suggests that lateral gene transfer may have occurred between thermophilic Eubacteria and Archaea.     

Preliminary observations of a bacteriophage infecting Xenorhabdus luminescens (Enterobacteriaceae)

A bacteriophage infective to Xenorhabdus luminescens, a bacterial symbiont of heterorhabditid nematodes, was recovered from insects that supported poor nematode development. Plaque tests showed the phage particles to be infective only to primary and not secondary colonies of X. luminescens. The phage was not infective to X. nematophilus primaries or secondaries. The bacteriophage particles ranged 80-90 nm in length, with the head ranging from 40 to 50 nm in diameter. Restriction analysis was performed on isolated bacteriophage DNA. This first report of a bacteriophage from Xenorhabdus species has practical implications since it could be detrimental to cultures of Heterorhabditis nematodes that are being produced throughout the world for the biological control of insects.     

3-A resolution structure of a protein with histone-like properties in prokaryotes

The 3-A structure of DNA-binding protein II, which exhibits histone-like properties in bacteria, has been determined. The molecule is dimeric and appears to bind to the phosphate backbone of DNA through two symmetry-related arms. A mechanism by which the protein induces DNA supercoiling is proposed.     

Synaptic boutons in the hippocampus: Changes are produced by age and experience

Zusammenfassung Erstmaliger morphometrischer Nachweis bei 2 Gruppen reifer, altersunterschiedlicher Ratten, dass die Zahl der Synapsen im Hippocampus mit dem Alter zunimmt, wobei die effektive Steigerungsrate auch mit Umwelteinflüssen zusammenhängen könnte.

---

---

This work was supported by grants from the U.S. National Institutes of Health to JJB (No. NS-06164) and to LEW,Jr., (No. NS-09358) and funds from the Center for Neurobiological Sciences of the University of Florida (No. NIH-MH-10320).     

Isolation of sodium-complexing polypeptides from mammalian blood and cardiac muscle.

Two distinct polypeptides have been isolated from rat heart and ox blood. They are both found to be effective in forming complexes with sodium ions, and it is suggested that they may have a function in stabilizing sodium ion activity.