Is cytomegalovirus a cause of ureteral stricture in renal transplant recipients?

Cytomegalovirus (CMV) is regarded as a predominant infectious agent in solid organ transplants. CMV disease has highly protean clinical manifestations. Nevertheless, urinary tract involvement seems to be very rare during CMV infection. We report two cases of renal transplant recipients in whom ureteral stricture developed in the course of CMV disease. Histologic data were available for them and were consistent with CMV infection. We discuss previous case reports and propose physiopathologic mechanisms. Received: 3 October 1996 Received after revision: 13 February 1997 Accepted: 17 February 1997     

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.     

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.     

Effect of losartan on haemoglobin concentration in renal transplant recipients - a retrospective analysis

Purpose of study: To evaluate the effect of angiotensin II type 1 receptor antagonist, losartan, on post-transplant erythrocytosis. Methods: We retrospectively analyzed the influence of losartan therapy on haemoglobin levels of renal transplant recipients. Twenty-eight patients who received losartan therapy to control hypertension were divided into two groups. In 10 patients, losartan therapy was initiated after treatment with ACE inhibitors which was discontinued due to adverse reactions (group A). Group B consisted of 18 patients treated with losartan who had never received ACE inhibitors. Results: There was no difference in mean haemoglobin concentration and haematocrit between the two groups before the onset of losartan therapy. In Group B, mean haemoglobin concentration and haematocrit decreased from 137±20 g/l and 0.4 at the start of losartan therapy to 120±16 g/l (P <0.0005) and 0.35 (P <0.0005), respectively 3 months later. In Group A, neither haemoglobin nor haematocrit differed between the onset of losartan therapy and the end of the study. Serum creatinine increased from 158 &mgr;mol/l±78 to 172 &mgr;mol/l±80 in Group B (P 7lt;0.005), but remained stable in Group A. Plasma protein concentrations remained stable in each group and there was no change in diuretic therapy during the study. Conclusion: Our study suggests that losartan therapy decreases haemoglobin in renal transplant recipients.      

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.