Dynamics of immune granuloma formation in a Leishmania braziliensis-induced self-limiting cutaneous infection in the primate Macaca mulatta.

In order to unravel the physiopathology of leishmaniasis in humans, it is necessary to better understand how Leishmania are able to survive for years within immunologically active granulomas. In the present study, we used a macaque (Macaca mulatta) model of infection with Leishmania braziliensis as a means of assessing the usefulness of this primate system. This model more closely mirrors human protective immunity to Leishmania than the murine model; therefore, we used it to study the host inflammatory granulomatous response involved in the control of cutaneous leishmaniasis. Infected primates developed localized long-term skin ulcerations, but complete spontaneous clinical healing occurred in all infected animals. The infection induced the recruitment and activation of inflammatory mast cells, granulocytes, mononuclear phagocytes, and lymphocytes at the site of infection. During the acute reaction, polymorphonuclear leukocytes were more prominent than other cell types and apparently destroyed many parasites; macrophages then rapidly engulfed dying neutrophils together with their parasitic cargo. In the chronic phase, persisting parasites induced a typical T helper (Th) cytokine, type 1-mediated, immunity-induced granulomatous reaction. By this time, more or less differentiated macrophage accumulations were found, and these evolved to become mature tissue granulomas consisting of all the specific cell types found within human granulomas. In the healing stage, fibroblasts proliferated at the periphery and finally invaded the granulomas with fibrotic substitution. These findings point to the feasibility of using this model to elucidate the potentially disabling Th1-cell mechanisms that may eventually render the host granulomatous response inadequate for fighting L. braziliensis infections.

Response of the growth plate of uremic rats to human growth hormone and corticosteroids.

Children with chronic renal failure in general present growth retardation that is aggravated by corticosteroids. We describe here the effects of methylprednisolone (MP) and recombinant human growth hormone (rhGH) on the growth plate (GP) of uremic rats. Uremia was induced by subtotal nephrectomy in 30-day-old rats, followed by 20 IU kg-1 day-1 rhGH (N = 7) or 3 mg kg-1 day-1 MP (N = 7) or 20 IU kg-1 day-1 rhGH + 3 mg kg-1 day-1 MP (N = 7) treatment for 10 days. Control rats with intact renal function were sham-operated and treated with 3 mg kg-1 day-1 MP (N = 7) or vehicle (N = 7). Uremic rats (N = 7) were used as untreated control animals. Structural alterations in the GP and the expression of anti-proliferating cell nuclear antigen (PCNA) and anti-insulin-like growth factor I (IGF-I) by epiphyseal chondrocytes were evaluated. Uremic MP rats displayed a reduction in the proliferative zone height (59.08 +/- 4.54 vs 68.07 +/- 7.5 microm, P < 0.05) and modifications in the microarchitecture of the GP. MP and uremia had an additive inhibitory effect on the proliferative activity of GP chondrocytes, lowering the expression of PCNA (19.48 +/- 11.13 vs 68.64 +/- 7.9% in control, P < 0.0005) and IGF-I (58.53 +/- 0.96 vs 84.78 +/- 2.93% in control, P < 0.0001), that was counteracted by rhGH. These findings suggest that in uremic rats rhGH therapy improves longitudinal growth by increasing IGF-I synthesis in the GP and by stimulating chondrocyte proliferation.

Oral hairy leukoplakia. Histopathologic and cytopathologic features of a subclinical phase.

Accurate diagnosis of oral hairy leukoplakia (OHL) is important because it may be an early indicator of undiagnosed HIV infection; moreover, it may be a prognostic indicator. Our purpose was to investigate the histopathologic features of subclinical OHL and to evaluate and support the rationale of detecting subclinical OHL with cytopathology. The Epstein-Barr virus (EBV) was detected by immunohistochemistry and in situ hybridization in 4 cases of macroscopically normal lateral borders of tongue mucosa from 8 AIDS necropsies and in none of 8 controls. The histopathologic features were specific when based on nuclear changes: Cowdry type A inclusion, ground glass, and nuclear beading. Smears were obtained from 50 patients with AIDS, without OHL, from the scraping of lateral borders of the tongue. Numerous clusters of the cells were associated with Candida organisms (30% of cases). Nuclear changes were observed in 12 patients (24%) on both sides of the tongue. We describe the histopathologic features of subclinical OHL, and our observations suggest that cytopathology can detect OHL in the subclinical phase.

Identification of growth hormone receptor in localised neurofibromas of patients with neurofibromatosis type 1.

BACKGROUND: The hallmark of neurofibromatosis type 1 (NF1) is the development of multiple neurofibromas. Solitary neurofibroma may occur in an individual who does not have NF1, but multiple neurofibromas tend to develop only in those with NF1. It has been suggested that hormones may influence the neurofibromas of patients with NF1. The evidence that hormones may influence the growth of neurofibromas comes mainly from the observation that localised neurofibromas of patients with NF1 commonly grow during puberty and pregnancy. Because growth hormone (GH) concentrations increase during puberty, it is possible that GH influences the growth of these tumours. AIMS: To investigate the presence of GH receptors (GHRs) in neurofibromas. METHODS: By means of immunohistochemistry, the presence of GHRs was investigated in two groups of patients: 16 patients without NF1 with solitary neurofibromas (group A) and 10 patients with NF1 with localised neurofibromas (group B). RESULTS: Six of the 16 patients in group A had neurofibromas that were immunopositive for GHR, whereas nine of the 10 patients in group B were immunopositive. CONCLUSIONS: Most patients with NF1 have localised neurofibromas that express GHR. This suggests that GH may play some role in the development of localised neurofibromas in patients with NF1.

Thymic extracellular matrix in Down's syndrome.

Down's syndrome (DS) is associated with cellular and humoral immunological abnormalities, and altered histology of the lymphoid and epithelial compartments of the thymus has been reported. In the present study, we investigated the extracellular matrix (ECM) of six DS thymuses. A novel fibroblast-containing network was demonstrated in the cortical region with anti-fibronectin, anti-type I collagen and anti-type IV collagen antibodies. Rupture sites of the basement membrane were also observed. Since the ECM is essential to normal thymic ontogeny, it is likely that the severe intrathymic ECM structure changes occurring in DS may be linked to abnormal cortical thymocyte depletion.

Insulin impairs the maturation of chondrocytes in vitro.

The precise nature of hormones and growth factors directly responsible for cartilage maturation is still largely unclear. Since longitudinal bone growth occurs through endochondral bone formation, excess or deficiency of most hormones and growth factors strongly influences final adult height. The structure and composition of the cartilaginous extracellular matrix have a critical role in regulating the behavior of growth plate chondrocytes. Therefore, the maintenance of the three-dimensional cell-matrix interaction is necessary to study the influence of individual signaling molecules on chondrogenesis, cartilage maturation and calcification. To investigate the effects of insulin on both proliferation and induction of hypertrophy in chondrocytes in vitro we used high-density micromass cultures of chick embryonic limb mesenchymal cells. Culture medium was supplemented with 1% FCS + 60 ng/ml (0.01 microM) insulin and cultures were harvested at regular time points for later analysis. Proliferating cell nuclear antigen immunoreactivity was widely detected in insulin-treated cultures and persisted until day 21 and [ 3H]-thymidine uptake was highest on day 14. While apoptosis increased in control cultures as a function of culture time, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-labeled cells were markedly reduced in the presence of insulin. Type II collagen production, alkaline phosphatase activity and cell size were also lower in insulin-treated cultures. Our results indicate that under the influence of 60 ng/ml insulin, chick chondrocytes maintain their proliferative potential but do not become hypertrophic, suggesting that insulin can affect the regulation of chondrocyte maturation and hypertrophy, possibly through an antiapoptotic effect.

[Oral hairy leukoplakia: histopathologic features of subclinical stage]. / Leucoplasia pilosa oral: aspectos histopatológicos da fase subclínica.

Oral hairy leukoplakia (OHL) is one of the most common oral manifestations of AIDS, with diagnostic and prognostic value. OHL is associated to the Epstein-Barr virus and presents clinical and histological defined characteristics. There have already been reports about a subclinical stage of OHL, although they lacked histopathologic characterization. The present study had the aim to describe the histopathological characteristics of subclinical hairy leukoplakia, as well as to carry out a comparative analysis between clinical and subclinical OHL. For that, 11 cases were analyzed--5 biopsies from patients who presented with the lesion and 6 samples from the borders of tongues obtained in necropsies. The histopathological findings in subclinical OHL were: absence of parakeratosis and papillomatosis, mild acanthosis, ballooning cells and nuclear alterations. In situ hybridization and immunostaining were positive for EBV in the nuclear alterations identified in the histopathological analysis. Based on the identification of EBV in the nuclear alterations, it was possible to conclude that subclinical OHL, similarly to the clinical lesion, presents histopathological features that are specific and sufficient to establish the definitive diagnosis, regardless of the identification of the virus.

Spatial patterns of dispersion and pollution sources for arsenic at Lousal mine, Portugal.

This study uses geostatistical modelling to identify hot spots of metal contamination produced by hazardous mining tailings from an inoperative Portuguese mine. Lousal is one of the many massive sulphide deposits of the Iberian Pyrite Belt. The mine is now closed, but the heavy metal enriched tailings remain at the site. Applying geostatistics to the diagnosis of this potentially contaminated area we aim to assess the quality of the soil, namely through a risk probability mapping for arsenic, for a better knowledge about the vulnerability of the soil to arsenic contamination. To achieve this aim, the initial variable was transformed into two indicator variables using the risk-based standards (intervention values) for soils, as proposed by Swartjes (1999), as the limit value. To account for the spatial structure, sample variograms were computed for the main directions of the sampling grid and a spherical model was fitted to the variables (arsenic raw data and indicator variables). The parameters of the model were used in the estimation process. To assess the vulnerability of the soil towards the mining works, a soil quality probability mapping for arsenic was carried out showing contamination probabilities in the area. The use of indicator kriging, as an alternative to other more complex kriging methods, in the soil data of the Lousal mine, produced unbiased soil quality maps.

Is the thymus a target organ in infectious diseases?

The thymus is a central lymphoid organ, in which T cell precursors differentiate and generate most of the so-called T cell repertoire. Along with a variety of acute infectious diseases, we and others determined important changes in both microenvironmental and lymphoid compartments of the organ. For example, one major and common feature observed in acute viral, bacterial and parasitic diseases, is a depletion of cortical thymocytes, mostly those bearing the CD4-CD8 double positive phenotype. This occurs simultaneously to the relative enrichment in medullary CD4 or CD8 single positive cells, expressing high densities of the CD3 complex. Additionally we noticed a variety of changes in the thymic microenvironment (and particularly its epithelial component), comprising abnormal location of thymic epithelial cell subsets as well has a denser Ia-bearing cellular network. Moreover, the extracellular matrix network was altered with an intralobular increase of basement membrane proteins that positively correlated with the degree of thymocyte death. Lastly, anti-thymic cell antibodies were detected in both human and animal models of infectious diseases, and in some of them a phenomenon of molecular mimicry could be evidenced. Taken together, the data reviewed herein clearly show that the thymus should be regarded as a target in infectious diseases.

Response of the growth plate of uremic rats to human growth hormone and corticosteroids

Children with chronic renal failure in general present growth retardation that is aggravated by corticosteroids. We describe here the effects of methylprednisolone (MP) and recombinant human growth hormone (rhGH) on the growth plate (GP) of uremic rats. Uremia was induced by subtotal nephrectomy in 30-day-old rats, followed by 20 IU kg-1 day-1 rhGH (N = 7) or 3 mg kg-1 day-1 MP (N = 7) or 20 IU kg-1 day-1 rhGH + 3 mg kg-1 day-1 MP (N = 7) treatment for 10 days. Control rats with intact renal function were sham-operated and treated with 3 mg kg-1 day-1 MP (N = 7) or vehicle (N = 7). Uremic rats (N = 7) were used as untreated control animals. Structural alterations in the GP and the expression of anti-proliferating cell nuclear antigen (PCNA) and anti-insulin-like growth factor I (IGF-I) by epiphyseal chondrocytes were evaluated. Uremic MP rats displayed a reduction in the proliferative zone height (59.08 ± 4.54 vs 68.07 ± 7.5 æm, P < 0.05) and modifications in the microarchitecture of the GP. MP and uremia had an additive inhibitory effect on the proliferative activity of GP chondrocytes, lowering the expression of PCNA (19.48 ± 11.13 vs 68.64 ± 7.9 percent in control, P < 0.0005) and IGF-I (58.53 ± 0.96 vs 84.78 ± 2.93 percent in control, P < 0.0001), that was counteracted by rhGH. These findings suggest that in uremic rats rhGH therapy improves longitudinal growth by increasing IGF-I synthesis in the GP and by stimulating chondrocyte proliferation.

Insulin impairs the maturation of chondrocytes in vitro

The precise nature of hormones and growth factors directly responsible for cartilage maturation is still largely unclear. Since longitudinal bone growth occurs through endochondral bone formation, excess or deficiency of most hormones and growth factors strongly influences final adult height. The structure and composition of the cartilaginous extracellular matrix have a critical role in regulating the behavior of growth plate chondrocytes. Therefore, the maintenance of the three-dimensional cell-matrix interaction is necessary to study the influence of individual signaling molecules on chondrogenesis, cartilage maturation and calcification. To investigate the effects of insulin on both proliferation and induction of hypertrophy in chondrocytes in vitro we used high-density micromass cultures of chick embryonic limb mesenchymal cells. Culture medium was supplemented with 1 percent FCS + 60 ng/ml (0.01 æM) insulin and cultures were harvested at regular time points for later analysis. Proliferating cell nuclear antigen immunoreactivity was widely detected in insulin-treated cultures and persisted until day 21 and [ H]-thymidine uptake was highest on day 14. While apoptosis increased in control cultures as a function of culture time, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-labeled cells were markedly reduced in the presence of insulin. Type II collagen production, alkaline phosphatase activity and cell size were also lower in insulin-treated cultures. Our results indicate that under the influence of 60 ng/ml insulin, chick chondrocytes maintain their proliferative potential but do not become hypertrophic, suggesting that insulin can affect the regulation of chondrocyte maturation and hypertrophy, possibly through an antiapoptotic effect

Thymic extracellular matrix in Down's syndrome

Dow's syndrome (DS) is associated with cellular and humoral immunological abnormalities, and altered histology of the lymphoid and epithelial compartments of the thymus has been reported. In the present study, we investigated the extracellular matrix (ECM) of six DS thymuses. A novel fibroblast-containing network was demonstrated in the cortical region with anti-fibronectin, anti-type I collagen and anti-type IV collagen antibodies. Rupture sites of the baement membrane were also observed. Since the ECM is essential to normal thymic ontogeny, it is likely that the severe intrathymic ECM structure changes occuring in DS may be linked to abnormal cortical thymocyte depletion