Selection events in directing B cell development.

Homeostasis in the B cell compartment (as well as in T cells) is controlled by tightly regulated selection events. Throughout their life span, B cells are subjected to selection signals determining not only developmental progression, but also maturation and survival. It is now clear that most of these signals require the expression of B cell antigen receptor (or preB receptor) with functional signaling capacity. The administration of numerous mutations into the mouse germline enabled us to identify several checkpoints along the B cell developmental pathway, and provided us with powerful experimental tools to probe for selection events regulating developmental progression. In here, we will discuss recent studies in this field.

Effects of disclosure of traumatic events on illness behavior among psychiatric prison inmates.

To assess the health effects of writing about traumatic events in a clinical population, 98 psychiatric prison inmates were randomly assigned to 1 of 3 conditions in which they were asked to write about their deepest thoughts and feelings surrounding upsetting experiences (trauma writing condition), write about trivial topics (trivial writing control), or go about their daily routine without writing (no-writing control). Both writing groups wrote for 20 min per day for 3 consecutive days. Participants in the trauma condition reported experiencing more physical symptoms subsequent to the intervention relative to those in the other conditions. Despite this, controlling for prewriting infirmary visits, sex offenders in the trauma writing condition decreased their postwriting infirmary visits. These results are congruent with predictions based on stigmatization and inhibition.

Forming a story: the health benefits of narrative.

Writing about important personal experiences in an emotional way for as little as 15 minutes over the course of three days brings about improvements in mental and physical health. This finding has been replicated across age, gender, culture, social class, and personality type. Using a text-analysis computer program, it was discovered that those who benefit maximally from writing tend to use a high number of positive-emotion words, a moderate amount of negative-emotion words, and increase their use of cognitive words over the days of writing. These findings suggest that the formation of a narrative is critical and is an indicator of good mental and physical health. Ongoing studies suggest that writing serves the function of organizing complex emotional experiences. Implications for these findings for psychotherapy are briefly discussed.

Vascular endothelial growth factor and angiopoietin in liver regeneration.

Liver architecture remodeling following partial hepatectomy (PHx) involves the formation of a complex network of liver sinusoids through which the blood flows. The present study examines the involvement of vascular endothelial growth factor (VEGF) and angiopoietin-1 (ang-1) during liver regeneration. Following PHx, VEGF and ang-1 mRNA levels increase, followed by gradual return to baseline levels. RT-PCR analysis of VEGF mRNA reveals three isoforms, VEGF120, VEGF164 and VEGF188. Of the three, VEGF188 is the predominant isoform, VEGF120 being the less abundant. Although VEGF mRNA fluctuates following PHx, the relative expression of each isoform remains the same throughout the recovery process. The level of neuropilin-1, an accessory receptor of VEGF to main receptor corresponds with that of VEGF and ang-1. We have previously demonstrated the capacity of exogenous VEGF165 to stimulate liver cell proliferation following PHx. We now report similar effect using VEGF121, further demonstrating the benefit of manipulating growth factors where such an intervention is required.

Use of human CD4 transgenic mice for studying immunogenicity of HIV-1 envelope protein gp120.

HIV-1 envelope protein, gp120, is a major immunogenic protein of the AIDS virus. A specific feature of this protein is its interaction with the receptor protein, human CD4, an important component of the immune system. This interaction might affect the immunogenic properties of the gp 120 and modulate the immune response towards HIV. To test this hypothesis we used human CD4-transgenic mice for immunization with gp120. The dynamics of the immune response towards gp120, CD4 and other proteins was followed. The results show that the primary immune response to gp120 (two weeks) developed somewhat faster in CD4-transgenic mice versus non-transgenic mice. Both animals, however, ultimately mounted the same level of response over time. The primary immune response to gp120 when complexed with soluble CD4 before the immunization, developed similarly in both groups. The secondary immune response was earlier and markedly stronger in non-transgenic mice compared with the transgenic mice where a less efficient memory response to gp120 was observed. The ability of gp120 to directly interact with CD4+ helper lymphocytes appears to affect the humoral response towards this antigen. Moreover, these effects illustrate how viral modulation of these cells may in turn lead to potentially different states of immunological equilibrium.