The immune response of Drosophila melanogaster

Summary:  The response of the fruit fly Drosophila melanogaster to various microorganism infections relies on a multilayered defense. The epithelia constitute a first and efficient barrier. Innate immunity is activated when microorganisms succeed in entering the body cavity of the fly. Invading microorganisms are killed by the combined action of cellular and humoral processes. They are phagocytosed by specialized blood cells, surrounded by toxic melanin, or lysed by antibacterial peptides secreted into the hemolymph by fat body cells. During the last few years, research has focused on the mechanisms of microbial recognition by various pattern recognition receptors and of the subsequent induction of antimicrobial peptide expression. The cellular arm of the Drosophila innate immune system, which was somehow neglected, now constitutes the new frontier.     

Occupational airborne exposure of the general population of a Norwegian county.

Occupational airborne exposure was examined for a stratified sample (N = 1275) of the general population aged 18-73 years in Hordaland County, Norway. The subjects identified all jobs of more than six months since leaving school and stated whether they had been occupationally exposed to specific agents and work processes potentially harmful to the lungs. The prevalence in the population ever having been exposed was 18% for asbestos, 9% for quartz, 5% for aluminum dust, 6% for wood dust, 12% for metal gases, 12% for welding, 9% for soldering, and 1% for hairdressing. According to occupational title (last job), 3% of the population had held a job with a high degree of airborne exposure, 26% a job with moderate exposure, and 70% a job with no airborne exposure. During their worklife both the men and the women tended to leave polluted jobs more often than unpolluted jobs. Occupational exposure to airborne pollutants potentially harmful to the lungs is widespread in this Norwegian general population.     

Propriospinal myoclonus: utility of magnetic resonance diffusion tensor imaging and fiber tracking.

Propriospinal myoclonus (PSM) is a rare movement disorder characterized by involuntary spinal-generated muscular jerks that spread rostrally and caudally to other spinally innervated muscles. Most patients have no clear etiology, and conventional MRI of the spinal cord is generally normal. Here we report the use of magnetic resonance diffusion tensor imaging (DTI) and fiber tracking to detect tract-specific abnormalities in a patient with propriospinal myoclonus. As the patient had the fragile-X premutation and antithyroid antibodies, spinal cord DTI abnormalities may be related to these conditions. Tract-specific analysis may provide new insights into the pathophysiology of propriospinal myoclonus.     

Peritoneal dialysis catheters. Immediate outcome after 30 days]

Results of a retrospective study of 124 peritoneal dialysis catheters introduced in 74 patients from October 1982 to November 1991 showed that 91% of catheters were functional at 30 day follow up, allowing continuous ambulatory peritoneal dialysis to proceed under satisfactory conditions. However, surgical replacement was necessary in 21.81% (26 catheters) during the first month, due essentially to mechanical complications: exteriorized or non exteriorized leaks (7 cases), dysfunction with faulty perfusion or emptying (11 cases) and catheter displacement (3 cases). Five catheters (4.25%) had to be withdrawn because of infection, suggestive of the need for prophylactic antibiotic therapy. No determining factor could be found in the present series or in the literature to explain the genesis of these mechanical complications, the cause of which is without doubt multifactorial. Rapid surgical replacement allows functional survival of the majority of catheters without increasing the risk of infection.     

Structure-activity relationship of macrocyclic and linear gadolinium chelates: Investigation of transmetallation effect on the zinc-dependent metallopeptidase angiotensin-converting enzyme

Transmetallation between commercially available solutions of gadolinium (Gd) chelates and the zinc (Zn)-dependent angiotensin-converting enzyme (ACE) was investigated. In vitro, the strongest inhibitions were observed for the linear Gd complexes, Gd diethylene-triamine pentaacetic acid (DTPA) bis-methylamide (BMA) (IC₅₀ = .016 ± .006 mmol/1) and Gd-DTPA (IC₅₀ = .350 ± .034 mmol/1). The two macrocycles Gd tetraazacyclododecane tetraacetic acid (DOTA) and Gd-HP-DO3A were similar and 400 times less active than Gd-DTPA-BMA. These effects were mainly due to the presence of free ligand for DTPA and calcium (Ca) chelate in the case of DTPA-BMA because the addition of Zn²⁺ in the same quantities suppresses their inhibitory effects. In vivo, these two solutions of linear Gd chelates significantly inhibited ACE activity (Gd-DTPA: 67 ± 9% versus baseline; and Gd-DTPA-BMA: 73 ± 2% versus baseline at the clinical dose of .1 mmol/kg), whereas no significant effect was observed for the two macrocyclic chelates Gd-DOTA and Gd-HP-DO3A. Formulating the Gd chelate solution with either an excess of free ligand or Ca chelate (to decrease Gd³⁺ release) in the case of linear Gd chelate may have deleterious biologic consequences.     

Assessment of virulence of pigeon isolates of Salmonella enterica subsp. enterica serovar typhimurium variant copenhagen for humans

Salmonella enterica serovar Typhimurium variant Copenhagen was isolated from 5 of 152 (3.3%) feral pigeons from the city of Ghent (Belgium) and from 26 pooled fecal samples from 114 pigeon lofts (22.8%). These isolates belonged to phage type (PT) 99. Seven of the pigeon isolates were further compared in vitro to five human variant Copenhagen isolates, 2 isolates of PT 208, 1 isolate each of PT 120 and U302, and a nontypeable isolate. No differences in invasiveness in human intestinal epithelial Caco-2 cells were found. The human strains, however, were able to multiply significantly more inside human THP-1 macrophages than the pigeon strains. After inoculation of mice with a pigeon PT 99 strain, high numbers of Salmonella bacteria were shed with the feces, the internal organs were heavily colonized, and the animals showed severe clinical symptoms resulting in death. In conclusion, the less-pronounced ability of the pigeon variant Copenhagen strains to multiply inside human macrophages than human strains as well as the lack of human PT 99 isolates during 2002, despite the relatively high frequency of this PT in the pigeon population, suggest these strains to be of low virulence to humans. However, the high virulence for mice of the tested strain implies that rodents may act as reservoirs.     

Recombination does not generate pinworm susceptibility during experimental crosses between two mouse subspecies

The susceptibility to Aspiculuris tetraptera of European Mus musculus hybrids is thought to reflect the disruption of genomic co-adaptation through recombination of the parental genomes. Here, we compared the susceptibility to this parasite between parents and experimental hybrids (intersubspecific until F4, intrasubspecific F1, F2) to clarify the contributions of heterosis and subspecies incompatibility. F1 showed hybrid vigor. Unlike intrasubspecific F2, intersubspecific F2 were less resistant than F1, but revealed no increased susceptibility relative to the parents. Intersubspecific F3 and F4 showed the same hybrid vigor as F1. Heterosis contributed most to the resistance, but the differences between intra- and intersubspecific F2 suggested genomic incompatibilities between subspecies. However, the susceptibility did not increase through the recombination process, showing that disruption of co-adaptation does not directly affect resistance. Even if previous studies still support the selective role of parasites in the current hybrid zone, an alternative hypothesis on the origin of hybrid susceptibility is warranted.