Asymptomatic nerve hypertrophy in lepromatous leprosy: a clinical,electrophysiological and morphological study

Summary In order to learn more about early nerve lesions observed in leprosy, we performed a clinical, electrophysiological and morphological study in seven patients with untreated lepromatous leprosy, palpably enlarged radial cutaneous nerve and preserved sensation in the corresponding territory. The conduction velocity of the cutaneous radial nerve, which was decreased in all patients, did not significantly differ from that of a group of patients with lepromatous leprosy, hypertrophy of the radial cutaneous nerve and sensory loss. In contrast, the sensory action potential was significantly lower in patients with sensory loss, which demonstrates that axon loss is more important than demyelination in producing sensory loss. In all patients nerve enlargement was due to thickening of the epineurium and of the perineurium subsequent to inflammatory infiltrates and proliferation of fibroblasts and perineurial cells. In several fascicles, the inflammatory infiltrates and the infected cells infiltrated endoneurial connective tissue septa and blood vessels.Mycobacteria leprae were abundant in peri neurial cells, fibroblasts, macrophages, Schwarm cells and endothelial cells, and lymphocytic vasculitis present in all cases. The average density of myelinated fibres was 2600 SD 880 fibres/mm² (control: 7700 fibres/mm²), with marked differences between individual fascicles, versus 420 fibres/mm² in patients with nerve hypertrophy and sensory loss (range 0–2080 fibres/mm²). Single fibre preparations showed that segmental demyelination pre dominated in two patients, axonal degeneration in one, while inflammatory infiltrates and proliferation of connective tissue adhering to individual fibres were prominent in the others. Both infection of Schwann cells and secretory products released by mononuclear cells involved in the inflammatory process are likely to play a role in the lesions of nerve fibres observed in early stages of lepromatous leprosy.Presented in part at the Second Meeting of the European Neurological Society, Brighton (UK), June 1990     

Xenopus muscle development: from primary to secondary myogenesis.

Xenopus myogenesis is characterized by specific features, different from those of mammalian and avian systems both at the cellular level and in gene expression patterns. During early embryogenesis, after the initial molecular signals inducing mesoderm, the myogenic determination factors XMyoD and XMyf-5 are activated in presomitic mesoderm in response to mesoderm-inducing factors. After these first inductions of the myogenic program, forming muscles in Xenopus can have different destinies, some of these resulting in cell death before adulthood. In particular, it is quite characteristic of this species that, during metamorphosis, the primary myotomal myofibers completely die and are progressively replaced by secondary "adult" multinucleated myofibers. This feature offers the unique opportunity to totally separate the molecular analysis of these two distinct types of myogenesis. The aim of this review is to summarize our knowledge on the cellular and molecular events as well as the epigenetic regulations involved in the construction of Xenopus muscles during development.     

Linkage of the horizontally acquired ypm and pil genes in Yersinia pseudotuberculosis

The superantigen-encoding ypm gene and the pil gene cluster governing type IV pilus biogenesis have been laterally acquired by Yersinia pseudotuberculosis. PCR assays on 270 unrelated strains from various environmental and animal sources revealed a significant association of ypm and pil in isolates.     

Erythropoietin regulates hypoxic ventilation in mice by interacting with brainstem and carotid bodies

Apart from its role in elevating red blood cell number, erythropoietin (Epo) exerts protective functions in brain, retina and heart upon ischaemic injury. However, the physiological non-erythroid functions of Epo remain unclear. Here we use a transgenic mouse line (Tg21) constitutively overexpressing human Epo in brain to investigate Epo's impact on ventilation upon hypoxic exposure. Tg21 mice showed improved ventilatory response to severe acute hypoxia and moreover improved ventilatory acclimatization to chronic hypoxic exposure. Furthermore, following bilateral transection of carotid sinus nerves that uncouples the brain from the carotid body, Tg21 mice adapted their ventilation to acute severe hypoxia while chemodenervated wild-type (WT) animals developed a life-threatening apnoea. These results imply that Epo in brain modulates ventilation. Additional analysis revealed that the Epo receptor (EpoR) is expressed in the main brainstem respiratory centres and suggested that Epo stimulates breathing control by alteration of catecholaminergic metabolism in brainstem. The modulation of hypoxic pattern of ventilation after i.v. injection of recombinant human Epo in WT mice and the dense EpoR immunosignal observed in carotid bodies showed that these chemoreceptors are sensitive to plasma levels of Epo. In summary, our results suggest that Epo controls ventilation at the central (brainstem) and peripheral (carotid body) levels. These novel findings are relevant to understanding better respiratory disorders including those occurring at high altitude.     

Epidemiology and genetic characterization of HIV-1 isolates in the general population of Djibouti (Horn of Africa)

During a national survey in 2002 in Djibouti, serum samples were collected using a valid sampling scheme from 2423 Djiboutians representing the general population of urban and rural districts. The HIV-1 seroprevalence was 2%. The HIV-1 polymerase gene from 53 untreated patients was amplified. Phylogenetic analysis of 34 isolates revealed a majority of subtype C (73%) as well as other subtypes, including CRF02_AG recombinants (18%), subtype D (6%), and subtype A (3%).     

Antifungal coating by biofunctionalized polyelectrolyte multilayered films

The surface of medical devices is a common site of bacterial and fungal adhesion, first step to the constitution of a resistant biofilm leading frequently to chronic infections. In order to prevent such complications, several physical and chemical modifications of the device surface have been proposed. Here, we experiment a new type of topical antifungal coating using the layer-by-layer technique. The nanometric multilayer film obtained by this technique is functionalized by the insertion of a chromogranin A-derived antifungal peptide (CGA 47-66, chromofungin). We show that the embedded peptide keeps its antifungal activity by interacting with the fungal membrane and penetrating into the cell. In vitro studies demonstrate that such an antifungal coating is able to inhibit the growth of yeast Candida albicans by 65% and completely stop the proliferation of filamentous fungus Neurospora crassa. The cytotoxicity of such a coating was also assessed by growing human gingival fibroblasts at its surface. Finally, the antifungal coating of poly(methylmethacrylate), a widely used material for biomedical devices, is successfully tested in an in vivo oral candidiasis rat model. Taken together, these results assessed the functionalized multilayer films containing a new potent antifungal non-toxic peptide, as a novel and promising technique for local antifungal protection.     

Immunofluorescence technique using HeLa cells expressing recombinant nucleoprotein for detection of immunoglobulin G antibodies to Crimean-Congo hemorrhagic fever virus

A HeLa cell line continuously expressing recombinant nucleoprotein (rNP) of the Crimean-Congo hemorrhagic fever virus (CCHFV) was established by transfection with an expression vector containing the cDNA of CCHFV NP (pKS336-CCHFV-NP). These cells were used as antigens for indirect immunofluorescence (IF) to detect immunoglobulin G antibodies to CCHFV. The sensitivity and specificity of this IF technique were examined by using serum samples and were compared to those of the IF technique using CCHFV-infected Vero E6 cells (authentic antigen). Staining of the CCHFV rNP expressed in HeLa cells showed a unique granular pattern similar to that of CCHFV-infected Vero E6 cells. Positive staining could easily be distinguished from a negative result. All 13 serum samples determined to be positive by using the authentic antigen were also determined to be positive by using CCHFV rNP-expressing HeLa cells (recombinant antigen). The 108 serum samples determined to be negative by using the authentic antigen were also determined to be negative by using the recombinant antigen. Thus, both the sensitivity and the specificity of this IF technique were 100% compared to the IF with authentic antigen. The novel IF technique using CCHFV rNP-expressing HeLa cells can be used not only for diagnosis of CCHF but also for epidemiological studies on CCHFV infections.     

Interaction of Dr adhesin with collagen type IV is a critical step in Escherichia coli renal persistence

The pathogenic mechanism of recurrent or chronic urinary tract infection is poorly understood. Escherichia coli cells bearing Dr fimbriae display unique tropism to the basement membrane (BM)-renal interstitium that enables the bacteria to cause chronic pyelonephritis in experimental mice. The renal receptors for Dr-fimbriated E. coli are type IV collagen and decay-accelerating factor (DAF). We hypothesized that type IV collagen receptor-mediated BM-interstitial tropism is essential for E. coli to cause chronic pyelonephritis. To test the role of the type IV collagen tropism of Dr-fimbriated E. coli in renal persistence, we constructed an isogenic mutant in the DraE adhesin subunit that was unable to bind type IV collagen but retained binding to DAF and examined its virulence in the mouse model. The collagen-binding mutant DrI113T was eliminated from the mouse renal tissues in 6 to 8 weeks, while the parent strain caused persistent renal infection that lasted at least 14 weeks (P < or = 0.02). Transcomplementation with the intact Dr operon restored collagen-binding activity, BM-interstitial tropism, and the ability to cause persistent renal infection. We conclude that type IV collagen binding mediated by DraE adhesin is a critical step for the development of persistent renal infection in a murine model of E. coli pyelonephritis.     

High prevalence of hepatitis C virus type 5 in central France evidenced by a prospective study from 1996 to 2002

From 1996 to 2002, hepatitis C virus (HCV) typing was prospectively performed for 1,281 unselected HCV-infected and viremic patients, irrespective of their clinical status. Eighty-three patients (6.5%) were coinfected with human immunodeficiency virus (HIV) and HCV. A total of 1,195 strains were identified by a serotype screening (Murex HCV Serotyping 1-6 assay) and/or genotyping (Inno-LiPA HCV II) test. The distribution of HCV types showed an unusually high rate of type 5 (14.2%) that was stable over time and was the third most frequent type, after type 1 (59.1%) and type 3 (15.1%). HCV type 5 was more frequent in patients who were older than 50 (P = 10(-6)), but its frequency did not differ significantly by gender (P = 0.21). Serotyping was performed for 1,160 strains but failed for 30.2% of them. The efficiency depended on HIV status (for HCV-HIV-coinfected patients, half of the strains were untypeable) and HCV type. Genotyping was performed for 428 samples, with an overall efficiency of 99.3%. It failed in three cases, which were subsequently identified as HCV type 2. Serotyping and genotyping results for 39 patients showed discrepancies between the two methods for 4 patients, who had HCV type 2, type 6, or mixed infections. Thus, HCV type 5 may also be encountered frequently in Western countries. Its apparent confinement to a restricted area raises the question of how it emerged and underscores the need for further studies of HCV type prevalence, routes of transmission, pathogenicity, and responses to treatment.