Histochemical study of RNA content of neurones in the dorsal lateral geniculate nucleus during postnatal development.

Nuclear and cytoplasmic dLGN neurons were investigated by cytophotometric measurements of RNA. This study has been carried out in rats from birth to adulthood. In order to quantify the RNA content a cytophotometer was used. Extinction mean values were obtained which indicated RNA concentrations per surface unit. The nuclear and cytoplasmic surface were calculated simultaneously and from the product of the mean extinction and the surface the RNA total content was calculated. Our results have suggested that the changes are age-related. From day 1 to day 21 the neuronal size and RNA content increase; this may somehow be involved with the differentiation process. Around post-natal day 21 neuronal maturation may begin, reaching its optimal phase around day 42, on which the RNA concentration per surface unit, surface neuronal content and RNA total content are stable.     

Genetic relationship between Streptococcus pneumoniae isolates from nasopharyngeal and cerebrospinal fluid of two infants with Pneumococcal Meningitis

The molecular epidemiology of Streptococcus pneumoniae isolates from carriage and cerebrospinal fluid (CSF) concurrently recovered from the same individual has not yet been reported. By using pulsed-field gel electrophoresis, we demonstrated the genetic linkage among strains from CSF and nasopharynges of two children with pneumococcal meningitis.     

Loss of fibroblast Thy-1 expression correlates with lung fibrogenesis

Fibroblasts consist of heterogeneous subpopulations that have distinct roles in fibrotic responses. Previously we reported enhanced proliferation in response to fibrogenic growth factors and selective activation of latent transforming growth factor (TGF)-beta in fibroblasts lacking cell surface expression of Thy-1 glycoprotein, suggesting that Thy-1 modulates the fibrogenic potential of fibroblasts. Here we report that compared to controls Thy-1-/- C57BL/6 mice displayed more severe histopathological lung fibrosis, greater accumulation of lung collagen, and increased TGF-beta activation in the lungs 14 days after intratracheal bleomycin. The majority of cells demonstrating TGF-beta activation and myofibroblast differentiation in bleomycin-induced lesions were Thy-1-negative. Histological sections from patients with idiopathic pulmonary fibrosis demonstrated absent Thy-1 staining within fibroblastic foci. Normal lung fibroblasts, in both mice and humans, were predominantly Thy-1-positive. The fibrogenic cytokines interleukin-1 and tumor necrosis factor-alpha induced loss of fibroblast Thy-1 surface expression in vitro, which was associated with Thy-1 shedding, Smad phosphorylation, and myofibroblast differentiation. These results suggest that fibrogenic injury promotes loss of lung fibroblast Thy-1 expression, resulting in enhanced fibrogenesis.     

Allele-Specific PCR Method Based on pncA and oxyR Sequences for Distinguishing Mycobacterium bovis from Mycobacterium tuberculosis: Intraspecific M. bovis pncA Sequence Polymorphism

An allele-specific amplification method based on two genetic polymorphisms to differentiate Mycobacterium tuberculosis from Mycobacterium bovis was tested. Based on the differences found at position 169 in the pncA genes from M. tuberculosis and M. bovis, a PCR system which was able to differentiate most of the 237 M. tuberculosis complex isolates tested in one of the two species was developed. All 121 M. tuberculosis strains showed the expected base (cytosine) at position 169. Most of the M. bovis isolates had a guanine at the cited position. Nevertheless, 18 of the 116 M. bovis isolates, all of them goat isolates, showed the pncA polymorphism specific to M. tuberculosis. These results suggest that goat M. bovis may be the nicotinamidase-missing link at the origin of the M. tuberculosis species. Based on the polymorphism found at position 285 in the oxyR gene, the same system was used to differentiate M. tuberculosis from M. bovis. In this case, DNAs from all 121 M. tuberculosis isolates had the expected base (guanine) at this position. In addition, all 116 M. bovis isolates, including those from goats, showed the identical polymorphism (adenine). The oxyR allele-specific amplification method can differentiate M. bovis from M. tuberculosis, is rapid (results can be obtained in less than 3 h), and is easy to perform.     

Neuroprotective effects of IGF-I against TNFalpha-induced neuronal damage in HIV-associated dementia

Human immunodeficiency virus type 1 (HIV-1) infection often results in disorders of the central nervous system, including HIV-associated dementia (HAD). It is suspected that tumor necrosis factor-alpha (TNFalpha) released by activated and/or infected macrophages/microglia plays a role in the process of neuronal damage seen in AIDS patients. In light of earlier studies showing that the activation of the insulin-like growth factor I receptor (IGF-IR) exerts a strong neuroprotective effect, we investigated the ability of IGF-I to protect neuronal cells from HIV-infected macrophages. Our results demonstrate that the conditioned medium from HIV-1-infected macrophages, HIV/CM, causes loss of neuronal processes in differentiated PC12 and P19 neurons and that these neurodegenerative effects are associated with the presence of TNFalpha. Furthermore, we demonstrate that IGF-I rescues differentiated neurons from both HIV/CM and TNFalpha-induced damage and that IGF-I-mediated neuroprotection is strongly enhanced by overexpression of the wt IGF-IR cDNA and attenuated by the antisense IGF-IR cDNA. Finally, IGF-I-mediated antiapoptotic pathways are continuously functional in differentiated neurons exposed to HIV/CM and are likely supported by TNFalpha-mediated phosphorylation of I(kappa)B. All together these results suggest that the balance between TNFalpha and IGF-IR signaling pathways may control the extent of neuronal injury in this HIV-related experimental setting.     

During active viscerocutaneous leishmaniasis the anti-P2 humoral response is specifically triggered by the parasite P proteins.

In this work we show that in the sera from dogs naturally infected with the protozoan parasite Leishmania infantum there are antibodies that react specifically against the parasite acidic ribosomal proteins LiP2a and LiP2b, and that each one of the Leishmania P proteins elicits a specific humoral immune response. Using synthetic peptides, the antigenic epitope of these proteins has been mapped in a single region located adjacent to the C-terminal domain highly conserved among the eukaryotic P proteins. The anti-P antibodies elicited during the Leishmania infection do not recognize the conserved C-terminal domain of the parasite P proteins, in contrast with the findings reported in Chagas' disease or systemic lupus erythematosus. The antigenic epitopes of the LiP2a and LiP2b are almost identical in amino acid sequence. No reactivity against Trypanosoma cruzi and human P proteins was found in sera from L. infantum-infected dogs.