Biomedical subjects
Publications and source records attributed to R Carreño.
In the paper observability problems are considered in basic dynamic evolutionary models for sexual and asexual populations. Observability means that from the (partial) knowledge of certain phenotypic characteristics the whole evolutionary process can be uniquely recovered. Sufficient conditions are given to guarantee observability for both sexual and asexual populations near an evolutionarily stable state.
Strategic models of frequency-dependent viability selection, in terms of mathematical systems theory, are considered as a dynamic observation system. Using a general sufficient condition for observability of nonlinear systems with invariant manifold, it is studied whether, observing certain phenotypic characteristics of the population, the development of its genetic state can be recovered, at least near equilibrium.
BACKGROUND: Tyrosinase transcripts have been identified in a wide range of normal organs and neoplasms such as cutaneous nevi, breast carcinomas, liposarcomas and schwannomas. The cells responsible for these positive results have not been accurately identified yet, but they might correspond to either fully differentiated melanocytes, melanocytic precursors or cells bearing potential for melanocytic differentiation. OBJECTIVE: To assess the expression of tyrosinase mRNA in surgical resection specimens and peripheral blood samples from 2 patients with primary neuroendocrine carcinomas of the skin (PNCS). METHODS: The expression of tyrosinase mRNA transcripts was tested by means of a reverse-transcriptase and nested PCR technique, using specific primers, in tissue samples from surgical specimens and heparinized blood samples from 2 patients with PNCS. RESULTS: The results of the test were positive in the 2 specimens of PCNS but negative in blood samples. CONCLUSION: Our findings provide further support for the hypothesis that PNCS originates from a pluripotent stem cell capable of neuroendocrine cell differentiation, keratin production, and, as reported herein, tyrosinase mRNA expression. It remains to be seen whether this technique can also be applied to patients with PNCS, as an adjunct to staging and treatment planning.
A total of 207 patients with hemangiomas, vascular malformations, and lymphovenous malformations were treated by the same surgeon from 1980 to 1990. Thirty-seven patients with true hemangiomas underwent surgical treatment. Only those hemangiomas which caused functional or developmental disturbances or those with complications were treated; many more were allowed to regress spontaneously. Sixty-five patients with low-flow and 16 with high-flow vascular malformations were treated by using a variety of surgical approaches. In low-flow lesions, sclerosant therapy can be extremely effective, either alone, in small lesions, or combined with surgical resection or embolization, in larger lesions. Preoperative embolization and surgical excision are the treatment of choice in high-flow malformations. Twenty-seven patients with lymphovenous malformations had only surgical excision with a high success rate. Sixty-two patients with acquired "senile hemangiomas" underwent a single local excision with excellent results. When indicated, angiography has been of great value as a diagnostic procedure to provide information about the vascular dynamics and the extent of these lesions, although magnetic resonance imaging is now being used more frequently for this purpose. Selective angiography also was used as a therapeutic modality when embolization was part of the treatment protocol. A new classification based on clinical, histologic, and vascular flow characteristics of these lesions has been used to simplify the present nomenclature and to help in selection of the most appropriate treatment. It has the added value of being in the language of the radiologist, who should be a member of the vascular anomalies team.
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Explore the source record for details and available documents.
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The extracellular production of l-lysine in media with cane sugar, blackstrap molasses, or clarified sugar-cane juice by a previously obtained mutant of Ustilago maydis was studied. Enzymatically inverted clarified juice (medium J-3) gave 2.9 g of lysine per liter under the following conditions: inoculum, 5%; pH 5.8; temperature, 30 C; K(La) in the fermentors, 0.41 mmoles of O(2) per liter per min; fermentation time, 72 hr. The concentrate, obtained by direct evaporation and drying of the fermentation broth, could be used as a possible feed supplement because of its amino-acid and vitamin content.
Citric acid yields of 98.7% (sugar consumption basis) were reached in shaker flasks with mutant UV-ET-71-15 of Aspergillus niger in a resin-treated sucrose medium of the following composition (g/100 ml): sucrose, 14.0; NH(4)NO(3), 0.20; KH(2)PO(4), 0.10; MgSO(4).7H(2)O, 0.025; and (mg/liter): FeSO(4), 0.15 to 0.75; ZnSO(4), 0.10; and CuSO(4), 0.01. Yields of 75% were obtained in medium with resin-treated clarified syrup and 68% with ferrocyanide-treated blackstrap molasses. Optimal conditions included selection of appropriate pellets as inoculum at 3%, pH of 4.5, temperature at 30 C, agitation at 250 rev/min, and fermentation time of 8 days. The mutant tolerated high concentrations of trace elements.
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