rhDNase as an example of recurrent event analysis

We consider counting process methods for analysing time-to-event data with multiple or recurrent outcomes, using the models developed by Anderson and Gill, Wei, Lin and Weissfeld and Prentice, Williams and Peterson. We compare the methods, and show how to implement them using popular statistical software programs. By analysing three data sets, we illustrate the strengths and pitfalls of each method. The first example is simulated and involves the effect of a hidden covariate. The second is based on a trial of gamma interferon, and behaves remarkably like the first. The third and most interesting example involves both multiple events and discontinuous intervals at risk, and the three approaches give dissimilar answers. We recommend the AG and marginal models for the analysis of this type of data.     

Lack of correlation between in vitro and in vivo replication of precisely defined benz-a-anthracene adducted DNAs

Like other polycyclic aromatic hydrocarbons, certain metabolites of benz[a]anthracene have been implicated as potent carcinogens. These effects are thought to be caused by the covalent binding of these species to nucleophilic groups on the bases of DNA. To address the molecular mechanisms by which these molecules induce mutations, this study employed oligonucleotides containing four site-specific N6 adenine-benz[a]anthracene diol epoxide adducts. Using a prokaryotic in vivo replication system, we have shown that both non-bay region anti-trans-benz[a]anthracene adducts are essentially nonmutagenic. In contrast, the bay region anti-trans-benz[a]anthracene lesions do induce point mutations at the adduct site. The mutagenic frequency of these bay region lesions is dependent on the stereochemistry about the adduct-forming bond, as well as the strain of Escherichia coli in which they are replicated. The ability of the bacterial replication machinery to bypass the lesions does not correlate with the differences observed in their mutagenesis. While both non-bay region adducts are readily bypassed in vivo, the bay region adducts are both blocking to approximately the same degree. In vitro studies of the interactions of E. coli DNA polymerase III with these adducts have also been undertaken to further dissect the relationship between adduct structure and biological activity.     

Risk factors of infected pancreatic necrosis, its microbiology and antibiotic treatment

Acute pancreatitis is associated with greater and smaller necrosis in 20% of the cases. The lethality rate of sterile and infected necrosis is 10 and 15-40%, respectively. The results of a retrospective and a prospective study in acute pancreatitis have been analyzed in this study. Twenty patients suffering from infected necrosis due to acute necrotising pancreatitis were selected into the retrospective study. They were divided into two groups: Group 1 (N = 10) survivors, Group 2 (N = 10) those who died. The fate of patients was determined by their age, the severity of pancreatitis, and the effectiveness of the operation. In a prospective study 63 patients were operated due to benign pancreatic disease with fluid collection. Microbiological samples were taken during surgery in every case. It could be stated that the Enterobacteriaceae spp. play the principal role in the infection, and the anaerobic bacteria occur sporadically. The omission of bacteriological sample taking during surgery frustrates the targeted antibiotic treatment. The blood culturing may have useful contribution. The targeted antibiotic therapy based on relevant microbiological sample taking is substantial complementary of the surgical intervention in the treatment of the inflammatory pancreatic diseases.     

Two separate mechanisms of T cell clonal anergy to Mls-1

T cell tolerance to superantigen can be mediated by clonal anergy in which Ag-specific mature T cells are physically present but are not able to mount an immune response. We induced T cell unresponsiveness to minor lymphocyte stimulations locus antigen (Mls)-1a in mice transgenic for TCR V beta 8.1 in three different systems: 1) injection of Mls-1a spleen cells, 2) mating with Mls-1a mice, and 3) bone marrow (BM) chimeras in which Mls-1a is present only on nonhematopoietic cells. CD4+8-V beta 8.1+ cells from all these groups did not proliferate in response to irradiated spleen cells from Mls-1a mice. We compared the response of these cells by T cell/stimulator cell conjugate formation, Ca2+ mobilization, and proliferation assays. The mechanisms underlying the unresponsiveness of these T cells appear to differ. CD4+8-V beta 8.1+ cells from Mls-1a spleen cell-injected mice mobilized cytoplasmic Ca2+ but proliferated at a reduced level in response to cross-linking with anti-TCR mAb. However, these cells formed conjugates, mobilized Ca2+, and proliferated in response to Mls-1a when activated B cells were used as stimulators, although they produced reduced levels of IL-2. In Mls-1a/b V beta 8.1 transgenic mice, a subset in CD4+8-V beta 8.1+ cells did not mobilize cytoplasmic Ca2+ after TCR cross-linking. Their conjugate formation, Ca2+ mobilization, or proliferation in response to Mls-1a on activated B cells was undetectable. Finally, CD4+8-V beta 8.1+ cells from the BM chimeras proliferated to TCR cross-linking at a partially reduced level and formed conjugates, mobilized Ca2+, and proliferated in response to Mls-1a on activated B cells. These features suggest that the mechanisms underlying the maintenance of anergy in Mls-1a spleen cell-injected mice are distinct from those in Mls-1a mice.     

Nitric oxide mediates the formation of synaptic connections in developing and regenerating olfactory receptor neurons

Nitric oxide (NO) is a diffusible free radical that functions as a second messenger and neurotransmitter. NO synthase (NOS) is highly and transiently expressed in neurons of the developing olfactory epithelium during migration and establishment of primary synapses in the olfactory bulb. NOS is first expressed at E11 in cells of the presumptive nervous layer of the olfactory placode. NOS immunoreactivity persists in the descendants of these cells that differentiate into embryonic olfactory receptor neurons (ORNs). Olfactory NOS expression in the ORN and in its afferents rapidly declines after birth and is undetectable by P7. Following bulbectomy, NOS expression is rapidly induced in the regenerating ORN and is particularly enriched in their outgrowing axons. Immunoblot and Northern blot analyses similarly demonstrate an induction of NOS protein and mRNA expression, respectively, the highest levels of which coincide with peaks of ORN regeneration. These data argue against a role for NO in odorant-sensitive signal transduction, but suggest a prominent function for NO in activity-dependent establishment of connections in both developing and regenerating olfactory neurons.     

Creating tobacco control policy at the local level: implementation of a direct action organizing approach

This article describes the community activation and policy change process in seven Minnesota communities involved in the Tobacco Policy Options for Prevention (TPOP) study. The study's intervention employed a direct action organizing model, which relies on mobilizing large numbers of people to alter decision making and leverage the power of elites. As part of the organizing process, TPOP organizers and teams made 1,319 personal contacts with community members, generated 309 media stories, and initiated 445 public events related to tobacco use. These actions resulted in the establishment of comprehensive tobacco ordinances in all seven communities. The authors discuss the goals, training, activities and political factors relevant to four phases of the TPOP intervention: information gathering and team recruitment, community awareness building and ordinance development, preparing for city council, and ordinance establishment and enforcement. Included are suggestions for practitioners interested in using policy change and community-based advocacy to resolve public health problems.     

A single amino acid substitution in the antimicrobial defense protein cecropin B is associated with diminished degradation by leaf intercellular fluid

Degradation is one of several factors that may affect the level of accumulation of transgene products in plants. In plants engineered to secrete antimicrobial proteins to the intercellular compartment of leaves, the degenerative activity of proteases residing in leaf intercellular fluid (IF) could be critical to achieving the expected transgene function. We synthesized a structural analogue (MB39) of the antibacterial protein cecropin B and compared the susceptibility of both proteins to degradation in vitro by IF extracted from leaves of various crops. The half-life of the two proteins in the various IF extracts ranged from 3 min to 25.5 h, with the analogue MB39 displaying the longer half-life in IF from nine of 10 species. Overall, the half-life of MB39 averaged 2.9 times greater than that of cecropin B. Analysis of the peptides produced by endopeptidase activity in potato iF indicated that the 5.7-fold lower degradation rate of MB39 was associated with the substitution of valine for methionine at residue 11 of cecropin B. These findings point to the possibility of tailoring antimicrobial protein genes to reduce the rate of protein degradation in a particular target crop.