Creating low-power photomicrographs by digital scanning of histological sections

The recent introduction of digital film scanners in the medical-scientific field provided everyone dealing with light-microscopy an easy method to obtain low-power photomicrographs from entire histological sections. Direct scanning of the common microscope slide allows the easy creation of high quality images. The digital images obtained may be improved or retouched using dedicated software and then printed on paper or film. The required instrumentation is relatively unexpensive and neither skilled staff nor expertise of photographic techniques is required. This reduces costs and saves time. The obtained images may be employed in histopathology, embryology, histochemistry, image analysis and telepathology, and are suitable for scientific papers, educational purposes and lecturing, as well as for daily reporting. The authors bring their personal experience in this field, making also a complete literature review on the topic.     

A mouse model for infectious mononucleosis

Epstein-Barr virus (EBV) is a ubiquitous human gamma-herpesvirus that establishes life-long latency and is associated with lymphoproliferative disorders and the development of several malignancies. EBV infection is frequently, but not always, associated with the development of a syndrome termed infectious mononucleosis. The recent isolation and characterization of a murine gamma-herpesvirus, MHV-68 (gammaHV-68) has provided the first small animal model for studying immunity and pathogenesis of a gamma-herpesvirus in its natural host. MHV-68 has important biological and genetic similarities with the human gamma-herpesviruses. Following intranasal infection of mice with MHV-68, an acute respiratory infection in the lung develops and is cleared, followed by the establishment of latency. Similar to EBV, MHV-68 latency is largely established in B cells, although other cell types can be latently infected. The establishment of latency correlates with a prominent splenomegaly, polyclonal B cell activation with associated autoantibody production, and CD8+ T cell-dominated peripheral blood lymphocytosis, in many aspects mirroring EBV-induced infectious mononucleosis. There are key differences in the MHV-68- and EBV-induced CD8+ T cell responses however. Whereas the expanded CD8+ T cells associated with EBV-induced mononucleosis are largely the outgrowth of T cells responding to lytic viral epitopes elicited during the acute phase of the response, the CD8+ T cell lymphocytosis associated with MHV-68-induced infectious mononucleosis is dominated by an oligoclonal population of T cells expressing Vbeta4+ T cell receptors that are not reactive to acute viral epitopes. The focus of this article will be to highlight the similarities and differences in the infectious mononucleosis syndrome associated with human and murine gamma-herpesviruses.     

Interpopulation variability among Panstrongylus megistus (Hemiptera: Reduviidae) from Brazil

Comparisons were made among Panstrongylus megistus (Burmeister) from three areas of Brazil (Bahia, Minas Gerais, and Santa Catarina), where populations differ with regard to their degree of association with human dwellings. The following characters were studied: morphology of the eggs and the male genitalia; morphometry of the head and thorax; isoenzyme profile; enzymatic activity of the alpha-glycerophosphate dehydrogenase (alpha-GPDH); and cytogenetics. In general, differences were observed in the weight, diameter, and length of the egg among Bahia, Minas Gerais, and Santa Catarina populations. Differences were not observed in the architecture of the egg exochorion. The size of the median process of the pygophore of the male genitalia of individuals from Bahia differed from the other two populations. The Minas Gerais population presented the largest number of denticles in the endosome process. The morphometry of the head and thorax differentiated Santa Catarina from the Bahia and Minas Gerais populations. Phosphoglucomutase (EC 5.4.2.2., PGM) was the only enzyme out of 11 that showed polymorphism; the population from Minas Gerais was most polymorphic, whereas the population from Santa Catarina was monomorphic. Study of the alpha-GPDH activity and cytogenetics did not reveal differences among the three populations. Analysis of all the characters studied together with information on these three populations from previous publications allowed a phenogram to be constructed. Two distinct groups were evident, one represented by Santa Catarina and the other by Bahia and Minas Gerais. Considering the greater variability of the Minas Gerais and Bahia populations, we propose the inclusion of these states within the area of origin of P. megistus.     

Granulocyte-macrophage colony-stimulating factor regulates cytokine production in cultured macrophages through CD14-dependent and -independent mechanisms

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has multiple effects on the antigen phenotype and function of macrophages. In this study we investigated the effect of GM-CSF on cytokine production by macrophages. We found that GM-CSF may modify the tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) response to lipopolysaccharide (LPS) through two different mechanisms. Relatively early in culture, GM-CSF increases the amount of cytokines synthesized by responding cells; this effect appears to be unrelated to modulation of CD14 expression and LPS-binding capacity. After prolonged incubation, GM-CSF up-regulates both CD14 expression and LPS-binding capacity, and the frequency of cytokine-producing cells. Release of CD14 in the culture supernatant was decreased in the presence of GM-CSF, suggesting that a reduced shedding was responsible for the effect of GM-CSF on CD14 expression. Enhancement of cytokine production was also observed in GM-CSF-treated macrophages after stimulation by phorbol 12-myristate 13-acetate (PMA), thus indicating that GM-CSF affects both CD14-dependent and -independent cytokine production. Finally, GM-CSF did not modulate the LPS- and PMA-induced production of IL-10 and IL-12. We conclude that GM-CSF may play a role in manipulating the activation-induced expression of pro-inflammatory cytokines by macrophages. Enhanced production of these cytokines could play an important role in the pathogenesis of Gram-negative septic shock syndrome and in defence against infectious agents.     

Ultrastructural identification of the splenic follicular dendritic cells in the chicken

Background: There is a need to identify the follicular dendritic cells (FDC) of the chicken spleen at the ultrastructural level during a secondary immune response. Methods: The cells were identified after intravenous priming BSA and boosting with biotinylated BSA conjugated to colloidal gold particles. Monoclonal antibodies raised specifically either to chicken IgG or IgM were used to characterize these immune complex-trapping cells. Results: The FDC had an irregular morphology which varied through time, supporting the existence of two types of FDC in the chicken spleen, one showing filiform cell processes, the other provided with beaded dendrites. When the filiform dendrites were observed, the FDC bound the antigen on their surfaces. These dendrites showed an intrincate convoluted configuration, forming tightly wrapped networks near the cell body. The networks had the same features as those described in mammals as antigen retaining reticulum (ARR). In chickens, the ARR, which represents sites of antigen localization on FDC, reached maximum development on day 5 after the second injection of BSA and had disappeared by day 8. At this time FDC had beaded dendrites. Conclusions: Antigen is retained on FDC in the chicken spleen for long periods of time. © 1995 Wiley-Liss, Inc.     

Five human immunodeficiency virus type 1 phenotypic variants with different MT-2 cell tropisms correlate with prognostic markers of disease

OBJECTIVES: We correlated virologic and immunologic parameters of disease progression with cytopathogenicity of HIV isolates. STUDY DESIGN/METHODS: Human immunodeficiency virus type 1 (HIV-1) isolates from 207 patients with CD4+ cell counts < 500/mm3 were examined for biologic phenotype in MT-2 cells. We used a cross-sectional study design. RESULTS: Three subtypes of syncytium-inducing (SI) strains with different times of appearance of syncytia formation in cell culture and two subtypes of non-syncytium-inducing (NSI) isolates, with (NSI/MT2+) or without (NSI/MT2-) replicative capacity in MT-2 cells, were identified. Early SI strains were associated with the lowest CD4+ cell counts and the highest levels of viral load, and NSI/MT2- isolates correlated with the highest CD4+ cell counts and the lowest viral loads. Patients with late SI and NSI/MT2+ strains showed minimal differences in immunologic and virologic markers. CONCLUSIONS: Five HIV phenotypic variants that correlate significantly (P < 0.001) with markers of disease progression were identified.     

Antibody response after RSV infection in children younger than 1 year of age living in a rural area of Mozambique

Serological responses have been studied in respiratory syncytial virus (RSV) infected children < 1 year of age attending the outpatient department of the Manhiça District Hospital (Mozambique). Molecular characterization of viral RNA in nasopharyngeal aspirates from the infected children indicated a high level of genetic uniformity among the infecting viruses, all of which belonged to a single genotype of RSV group A. A representative virus strain, Moz00, was isolated from one of the infants and was used, together with the group A strain A2 and the group B strain 8/60, as antigens in the quantification of infant antibody responses. In this study, 97.5% (39/40) and 96.4% (27/28) of infected children produced an antibody response against Moz00 detected by the membrane fluorescent antibody test (MFAT) and the neutralization test (NT), respectively. Seroconversion rates decreased when the A2 and 8/60 strains were used as antigen in MFAT (95.4% and 88.2%, respectively) or NT (81.8% and 54.5%, respectively), indicating that antibody responses had both group‐ and strain‐specific components. Antibodies in convalescent sera of infected children were compared with maternally derived antibodies detected in a group of children also < 1 year of age, but with no evidence of RSV infection. The convalescent sera exhibited reduced neutralizing capacity when the 8/60 strain was used as antigen (P = 0.028), suggesting that the infant antibody response lacks neutralizing capacity against strains of the heterologous virus group. Restricted cross‐reactivity and neutralizing capacity of antibodies generated by young children might be expected to induce only moderate protection in subsequent epidemics against genetically distant strains. J. Med. Virol. 69:579–587, 2003. © 2003 Wiley‐Liss, Inc.