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Biomedical subjects

M da Cunha

Publications and source records attributed to M da Cunha.

6 recordsLinked to original sources
PubMed2006

Isolation and intracellular localization of insulin-like proteins from leaves of Bauhinia variegata.

Evidence based on immunological cross-reactivity and anti-diabetic properties has suggested the presence of insulin-like peptides in plants. The objective of the present study was to investigate the presence of insulin-like proteins in the leaves of Bauhinia variegata ("pata-de-vaca", "mororó"), a plant widely utilized in popular medicine as an anti-diabetic agent. We show that an insulin-like protein was present in the leaves of this plant. A chloroplast protein with a molecular mass similar to that of bovine insulin was extracted from 2-mm thick 15% SDS-PAGE gels and fractionated with a 2 x 24 cm Sephadex G-50 column. The activity of this insulin-like protein (0.48 mg/mL) on serum glucose levels of four-week-old Swiss albino (CF1) diabetic mice was similar to that of commercial swine insulin used as control. Further characterization of this molecule by reverse-phase hydrophobic HPLC chromatographic analysis as well as its antidiabetic activity on alloxan-induced mice showed that it has insulin-like properties. Immunolocalization of the insulin-like protein in the leaves of B. variegata was performed by transmission electron microscopy using a polyclonal anti-insulin human antibody. Localization in the leaf blades revealed that the insulin-like protein is present mainly in chloroplasts where it is also found associated with crystals which may be calcium oxalate. The presence of an insulin-like protein in chloroplasts may indicate its involvement in carbohydrate metabolism. This finding has strengthened our previous results and suggests that insulin-signaling pathways have been conserved through evolution.

Animals↗
PubMed2002

Structure, morphology, and composition of silicon biocomposites in the palm tree Syagrus coronata (Mart.) Becc.

Syagrus coronata is an economically important palm tree grown as an ornament, for the oil extracted from its seeds, and the wax from its leaves which has several applications in industry. Silicon biocomposites were analyzed in leaves of S. coronata. Silica bodies were found as extracellular silica masses between the hypodermal-layer cell walls and in granules present in the vacuoles of palisade cells. Scanning electron microscopy of the hypodermal layer of cells showed a collection of spherical bodies embedded in enveloping cavities that outlined the general structure of the bodies. Globular subunits with sharp edges formed the spherical bodies that ranged from 6 to 10 microm in diameter (average, 7.8 microm). X-ray microanalysis detected only silicon and oxygen homogeneously distributed throughout the bodies. Vacuoles of palisade cells contained a large number of granules ranging from 20 nm to 1.2 microm in size (average, 300 nm). Transmission electron microscopy associated with electron spectroscopic imaging and electron energy loss spectroscopy were used to determine the elemental composition of the granules. Vacuolar granules were amorphous and composed of silicon and oxygen, suggesting they consist of amorphous silica biominerals. No nitrogen, indicative of organic matter, was detected in the granules.

Cell Wall↗
PubMed2000

The laticifer system of Chamaesyce thymifolia: a closed host environment for plant trypanosomatids.

Specimens of Chamaesyce thymifolia (Euphorbiaceae) infected and uninfected by Phytomonas sp., a parasite of the Trypanosomatidae family, were anatomically and ultrastructurally analyzed with special emphasis on the laticifer system. C. thymifolia presents branched non-articulated laticifers and was heavily infected by Phytomonas sp. in all collection sites. Infection was often observed in the initial stages inside the vacuole, when the latex particles could be seen. In intermediary stages of laticifer differentiation, Phytomonas sp. were found free in the cytoplasm, inside small vacuoles or in the central vacuole. In differentiated laticifers that had only the plasma membrane, Phytomonas sp. were free in the latex and close to the cell membrane. Infected and uninfected plants showed identical anatomy and ultrastructure and the starch grain numbers in the latex were not reduced in the presence of this flagellate. Biochemical analysis of the latex of infected and uninfected plants presented similar levels of protein, carbohydrate and beta-1,3-glucanase, suggesting that this species is not pathogenic for the host. Besides, all infected plants complete its life cycle. Plants infected with Phytomonas presented occasionally virus like particles and bacteria inside the laticifer tubes.

Animals↗
PubMed1988

Male reproductive function in long-term survivors of childhood cancer.

We evaluated reproductive function in 27 male long-term survivors of childhood cancer treated during the prepubertal and pubertal period. Sperm samples were obtained from 23 patients; four who refused to provide specimens indicated that they had fathered normal healthy children. Thirteen patients were 12 years old or younger at the time of diagnosis and initiation of therapy. Chemotherapy was calculated according to the cumulative amount of drug administered and correlated with the surface area. Sterility was associated with large doses of single alkylating agents or reduced doses administered with other agents in combination regimens. It was noted in boys treated in both the prepubertal and pubertal period. Sterility was also observed in patients who received testicular radiation alone or in combination with chemotherapy. However, it was not an inevitable consequence in all patients, despite treatment with similar or identical regimens. Fertility potential could not be predicted by clinical examination (testicular size) or gonadotrophin and testosterone values. The results were compared to published reports of treatment-induced sterility in adult males. Additional investigations are required to establish more accurate correlations of dosage with reproductive potential.

Adolescent↗
PubMedDate not supplied

Extramedullary myeloid tumors in children: the limited value of local treatment.

PURPOSE: To determine the incidence of extramedullary tumors (EMT) in Saudi Arabian children with acute myeloid leukemia, the factors associated with these tumors and the impact of local treatment on local tumor control, complete remission and survival rates. PATIENTS AND METHODS: One hundred children, median age 6 years, who received their primary treatment for acute myeloid leukemia at King Faisal Specialist Hospital and Research Center, from 1983 to 1997 were studied. EMT at diagnosis occurred in 18 (18%) patients at 25 sites. Meningeal leukemia, hepatosplenomegaly, lymph node enlargement, gingival hypertrophy, and cutaneous infiltration were not included in the definition of EMT. With these exclusions, children with EMT were younger than those without EMT (median age, 3.5 v. 7.5 years) and were more likely to have meningeal leukemia at diagnosis (33% v. 10%). The t(8;21) translocation was associated with a 47% EMT incidence compared with 23% without the translocation. Local radiation treatment was given to 16 of 25 (64%) EMT sites. RESULTS: The overall 5-year survival rate for all patients was 28%, and this was not significantly influenced by the drug regimen used, meningeal leukemia at diagnosis, the presence of the (8;21) translocation, M4 and M5 morphology combined, or EMT at diagnosis. Significant differences were observed in the 5-year survival rates for patients who underwent allogeneic bone marrow transplantation (52%; N = 37) and those who attained complete remission (CR) but did not undergo transplantation (21%; N = 44) and those who did not achieve complete remission with initial therapy (5%; N = 19). Systemic and local EMT CR was achieved in 17 of 18 patients with EMT, including 12 patients who underwent radiation treatment and 5 of 6 of those who did not. Isolated relapse was not seen at an EMT site and was not noted at any later stage of the disease. CONCLUSIONS: Permanent local control at sites of EMT was achieved in all patients who attained a bone marrow CR, whether or not the site was irradiated. Local radiation treatment of an EMT site did not appear to contribute to overall CR and survival rates. The use of radiation treatment should be conservative and limited to patients in whom there is a real and immediate threat to vision or renal function or when the spinal cord is compromised.

Acute Disease↗