Identifying drivers of forest resilience in long-term records from the Neotropics.

Here, we use 30 long-term, high-resolution palaeoecological records from Mexico, Central and South America to address two hypotheses regarding possible drivers of resilience in tropical forests as measured in terms of recovery rates from previous disturbances. First, we hypothesize that faster recovery rates are associated with regions of higher biodiversity, as suggested by the insurance hypothesis. And second, that resilience is due to intrinsic abiotic factors that are location specific, thus regions presently displaying resilience in terms of persistence to current climatic disturbances should also show higher recovery rates in the past. To test these hypotheses, we applied a threshold approach to identify past disturbances to forests within each sequence. We then compared the recovery rates to these events with pollen richness before the event. We also compared recovery rates of each site with a measure of present resilience in the region as demonstrated by measuring global vegetation persistence to climatic perturbations using satellite imagery. Preliminary results indeed show a positive relationship between pre-disturbance taxonomic richness and faster recovery rates. However, there is less evidence to support the concept that resilience is intrinsic to a region; patterns of resilience apparent in ecosystems presently are not necessarily conservative through time.

Dual Contribution of Mesenchymal Stem Cells Employed for Tissue Engineering of Peripheral Nerves: Trophic Activity and Differentiation into Connective-Tissue Cells.

Adult peripheral nerves in vertebrates can regrow their axons and re-establish function after crush lesion. However, when there is extensive loss of a nerve segment, due to an accident or compressive damage caused by tumors, regeneration is strongly impaired. In order to overcome this problem, bioengineering strategies have been employed, using biomaterials formed by key cell types combined with biodegradable polymers. Many of these strategies are successful, and regenerated nerve tissue can be observed 12 weeks after the implantation. Mesenchymal stem cells (MSCs) are one of the key cell types and the main stem-cell population experimentally employed for cell therapy and tissue engineering of peripheral nerves. The ability of these cells to release a range of different small molecules, such as neurotrophins, growth factors and interleukins, has been widely described and is a feasible explanation for the improvement of nerve regeneration. Moreover, the multipotent capacity of MSCs has been very often challenged with demonstrations of pluripotency, which includes differentiation into any neural cell type. In this study, we generated a biomaterial formed by EGFP-MSCs, constitutively covering microstructured filaments made of poly-ε-caprolactone. This biomaterial was implanted in the sciatic nerve of adult rats, replacing a 12-mm segment, inside a silicon tube. Our results showed that six weeks after implantation, the MSCs had differentiated into connective-tissue cells, but not into neural crest-derived cells such as Schwann cells. Together, present findings demonstrated that MSCs can contribute to nerve-tissue regeneration, producing trophic factors and differentiating into fibroblasts, endothelial and smooth-muscle cells, which compose the connective tissue.

Morphological Aspects of Oral Denticles in the Sharpnose Shark Rhizoprionodon lalandii (Müller and Henle, 1839) (Elasmobranchii, Carcharhinidae).

The oral denticles of some elasmobranchs are found on the surface of the oral cavity and are homologous to those on the body surface, being well developed, independent and non-growing, with varying morphology and distribution depending on the species. The structural and three-dimensional characteristics of oral denticles from the rostro-ventral surface of the sharpnose shark Rhizoprionodon lalandii were described following imaging by both light and scanning electron microscopy. The light microscopy results showed that the triangular shape of the denticles consisted of a base and an apex. Picrosirius staining showed the arrangement of collagen fibres and oral denticles, and a predominance of type-I collagen was found in both structures under polarized light. There was a broad homogeneous distribution of denticles on the ventral surface, forming a leaf-like shape with the cusp facing the caudal region. Interlocking, hexagonal, geometric structures on its rostral side and ridges on the rostral side of the oral denticles were observed under increased magnification. We concluded that the denticle morphology found in R. lalandii differ of others analysed species, and the descriptions of these structures therefore provide important information for the classification of the species. In this species, the main functions can be assigned to help reduce hydrodynamic drag, particularly by this being a species that uses ram ventilation, and to protect the epithelium of the oropharynx of abrasion and parasites.

The role of NO-cGMP pathway and potassium channels on the relaxation induced by clonidine in the rat mesenteric arterial bed.

The mechanisms involved in the vasodilation action of clonidine have not yet been completely elucidated. We investigated the potential mechanisms that seem to be involved in the clonidine vasodilator effect using rat isolated mesenteric arterial bed (MAB). In precontracted MAB, clonidine (10-300 pmol) induced a dose-dependent relaxation, that was inhibited by endothelium removal (deoxycholic acid - 2.5 mM) and reduced by the alpha(2) adrenoceptor inhibitors yohimbine (1-3 microM) and rauwolscine (1 microM). The endothelium-dependent vasodilation induced by clonidine was reduced by the nitric oxide (NO) synthase inhibitor L-NAME (0.3 mM) and guanylyl cyclase inhibitor ODQ (10 microM) but was not affected by indomethacin (3-10 microM) alone. High K+ (25 mM) solution reduced the vasodilator effect of clonidine that was further attenuated by L-NAME. In the presence of high K+ plus L-NAME, the residual vasodilator effect of clonidine was further reduced by indomethacin (3 microM). The Ca(2+)-dependent K+ channel (K+(Ca2+)) inhibitors, charybdotoxin (ChTx; 0.1 microM) plus apamin (0.1 microM), also reduced the vasodilation induced by clonidine, however this response was not further reduced in the presence of L-NAME as observed with acetylcholine (10 pmol). In the presence of ATP-dependent K+ channel (K+(ATP)) blocker, glibenclamide (10 microM), the inhibitory effect of ChTx plus apamin plus L-NAME was increased. In contrast, the vasodilation induced by clonidine was not affected by voltage-dependent K+ channels (K(V)) blocker, 4-aminopyridine (4-AP, 1 mM). In conclusion, our results demonstrate that clonidine activates alpha(2)-adrenoceptors in rat MAB and that the endothelium-dependent vasodilation is mediated by activation of NO-cGMP pathway, hyperpolarization due to activation of K+(Ca) and K+(ATP) channels. Prostaglandins might participate in the vasodilator effect of clonidine when NO and EDHF mechanisms are blunted.

Onychoprotothecosis: report of the first case in Brazil.

The present report describes a case of onychoprotothecosis caused by Prototheca wickerhamii in a nonimmunocompromized female. Dermatological examination showed yellowish discoloration of the left and right forefinger nails, showing onicolysis and hyperkeratosis. The repeated isolation of the algae Prototheca (organisms morula-like) as well as the repeated culture in media, Sabouraud agar, confirmed the diagnosis. The patient was successfully treated with tioconazol 1% topic solution. The aim of this paper was to present a rare condition.

Cutaneous protothecosis: report of a third Brazilian case.

The present report describes a case of cutaneous protothecosis caused by Prototheca wickerhamii in a nonimmunocompromised Brazilian female. Dermatological examination revealed a 15-cm diffusely infiltrated eczema-like plaque recovered with many pustule-like lesions on the right forearm. We emphasize the mycological and pathological aspects of this infection that can lead to misdiagnosis. The patient was successfully treated with itraconazole.

Dermatófitos e dermatofitoses na cidade de São Paulo no período de agosto de 1996 a julho de 1998 / Dermatophytes and dermatophytosis in the city of São Paulo, from August 1996 to July 1998

A distribuição das espécies de dermatófitos tem variado muito de região para região no decorrer do tempo. Variação no perfil ecológico dos dermatófitos pode influir na epidemiologia das dermatofitoses. O objetivo foi estudar a ecologia dos dermatófitos e a epidemiologia das dermatofitoses na cidade de São Paulo, no período de agosto de 1996 a julho de 1998. Durante um período de dois anos, todos os exames microscópicos diretos positivos para dermatófitos feitos na Clínica de Dermatologia da Santa Casa de São Paulo foram estudados. O dermatófito isolado com maior freqüência foi o T. rubrum (65,5 por cento), seguido por M. canis (13,7 por cento), T. tonsurans (10,6 por cento), T. mentagrophytes (7,3 por cento), E. floccosum (1,7 por cento)e M. gypseum (1,3 por cento). As variantes clínicas de dermatofitose predominantes foram: tinha do pé (25,9 por cento), tinha da unha (25,2 por cento) e tinha do corpo (22 por cento). A tinha do couro cabeludo apareceu com a freqüência de 17,1 por cento, enquanto a tinha inguinocrural e a tinha da mão foram as menos freqüêntes, com 9 por cento e 0,8 por cento, respepctivamente. Ecologia - Biota dermatítica constituída por seis espécies: T. rubrum, M. canis, T. tonsurans, T. mentagrophytes, E. floccosum e M. gypseum. Comparando os resultados obtidos com os de publicações anteriores referentes à Região Sudeste, verificou-se aumento da freqüência de T. tonsurans e T. rubrum, e diminuição da freqüência do T. mentagrophytes. Epidemiologia - predomínio de tinhas do pé, da unha e do corpo por T. rubrum em adultos e do couro cabeludo por M. canis em crianças. Aumento da freqüência de tinha do couro cabeludo e do corpo por T. tonsurans, quando comparada com a de outras publicações sobre a Região Sudetes em diferentes períodos

Dermatoses associadas às leveduras do gênero malassezia / Dermatosis associated with yeasts from Malassezia genus

A importância das leveduras do gênero Malassezia vem aumentando a partir do seu reconhecimento enquanto importantes patógenos em pacientes com algum tipo de imunodepressão. O esforço na identificação de novas espécies decorre da necessidade de entendimento mais abrangente da patogênese das dermatoses a elas associadas. A nova taxonomia dessas leveduras e todas as dermatoses a elas associadas são discutidas

Dermatophytosis caused by Trichophyton raubitschekii. Report of the first case in São Paulo, Brazil

The authors report the first case of dermatophytosis caused by Trichophyton raubitschekii in a patient from the State of São Paulo with Tinea corporis lesions localized on the buttocks. Culture on Sabouraud-agar with cycloheximide permitted the isolation and identification of the fungus, and the diagnosis was confirmed by Dr. Lynne Sigler, University of Alberta, Canada. Systemic treatment with fluconazole, 150 mg/week for 4 weeks, in combination with topical treatment with isoconazole initially yielded favorable results, with recurrence of the lesions after the medication was discontinued. This is the fifth case of this dermatophytosis published in the Brazilian medical literature

[A fibrolamellar variety of hepatocarcinoma in a young woman 17 years old]. / Hepatocarcinoma variedad fibrolamelar en una joven de 17 años de edad.

We report here the case of a 17-year-old female with typical fibrolamellar hepatocellular carcinoma, no hepatitis B or C viral infection and a normal, non-cirrhotic liver. Computed tomography and magnetic resonance imaging revealed a solid tumor with a central fibrous scar. A fibrolamellar hepatocellular carcinoma is an uncommon malignancy of unknown etiology, without cirrhosis, usually without an increase in tumor markers, and rarely associated with hepatitis B virus. It occurs mainly in young patients. This tumor presents a high resectability rate (48-100%), a good prognosis and a mean survival of 68 months. This tumor is an important differential diagnosis of space occupying lesions in younger adults.

[Giant acinic cell parotid gland adenocarcinoma of the papillary- cystic type]. / Adenocarcinoma gigante de células acinares de tipo quístico papilar en parótida.

A case of a 38-year-old male having an acinic cell adenocarcinoma of the parotid gland is reported. The tumor measured 22 cm and histologically it was of the papillary-cystic type. The following features were of interest: 1) the tumor size surpassed the size of previous reported acinic cell adenocarcinomas by 9 cm; and 2) the rarity of its histological variety (cystic papillary) demanded immunohistochemical and electron microscopic studies to confirm the diagnosis.

[Testicular lymphoma in two patients with AIDS and two without AIDS]. / Linfoma testicular en dos pacientes con SIDA y dos sin SIDA.

OBJECTIVE: To describe the clinical, morphological and inmunophenotypic characteristics and followup of testicular non Hodgkin lymphomas seen in a referral center. METHODS: We reviewed the cases of testicular lymphoma seen from 1987 to 1997. We obtained data of laboratory tests, radiological findings, clinical course, treatment and new immunohistochemical studies (CD45, CD20, CD43, Epstein-Barr virus latent membrane protein and antibodies UCHL-1). We performed a blind analysis to identify the morphological variables associated to the clinical course. The Fisher exact test was used for statistical significance identification. RESULTS: 53 patients with testicular tumors were seen. Four of them were lymphomas (7.5%) with a mean age of 47 years (range 33-73) and two of the four had AIDS. A comparative analysis showed major local invasion of surgical margins and systemic progression in the AIDS cases. Immunohystochemical testing showed that the neoplasia was formed by B cells negative for Epstein-Barr virus latent membrane protein. The two patients without AIDS showed no evidence of the disease after 64 and 144 months of followup. The AIDS cases died one and three months after the diagnosis of testicular lymphoma was made. CONCLUSIONS: The four cases of testicular lymphoma were of B cell lineage without immunohystochemical expression for Epstein-Barr virus latent membrane protein. There was a more aggressive clinical course in the cases associated with AIDS.

Immunogenetic profile of multiple sclerosis in Mexicans.

This is the first study on genetic markers in Mexican Mestizos with multiple sclerosis (MS). Patients were born in Mexico, had no family history of MS are middle-class, and have a high-level education. HLA class I, class II determinants, C2, C4, BF, GLO-1, ABO, and Rb red cell systems were analyzed and compared with results of 295 controls. Measles antibodies, glucose, IgG, total proteins, and cell count were measured in cerebrospinal fluid; anti-neuron, T-cell, and B-cell antibodies were determined in serum. MS in Mexican Mestizos was clinically similar to MS reported in high prevalence countries. DRw6, as previously found in Japanese patients, and its subtype, DRw13, were increased in patients in our study (pc = 0.0007, pc = 0.01, respectively), and the combination A3, B7, DR2, was also elevated (pc = 0.003). The polygenicity of the disease is emphasized by the excess of AB group carriers (pc = 0.01). IgG levels were high in patients with DR2 or DRw6 and 67% of the latter had anti-T cell antibodies. Severity of the disease was also related to the DR markers. It is suggested that at least two HLA-DR linked genes and the industrialized environment are important for the expression of MS in Mestizos.