121 resultados para backward differentiation formula
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In view of the importance of venereal transmission of bovine leptospirosis, the objective of the present study was to apply the polymerase chain reaction (PCR) to 26 serovars of Leptospira interrogans, L. borgpetersenii, L. santarosai, L. noguchii and L. biflexa, to determine the detection threshold in semen samples and to evaluate the possibility of differentiation among serovars using 19 restriction endonucleases. The results showed that all serovars were amplified and the detection threshold in semen samples of a bull was 100 bacteria/ml. Using endonucleases we could classify the 26 serovars into eight groups. The present results show that PCR is a method of great potential for the detection of Leptospira spp, at bovine artificial insemination centers. (C) 2000 Elsevier B.V. B.V. All rights reserved.
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In this work we have:investigated the growth and differentiation of bone marrow stem cells in mice bearing Ehrlich ascites tumor-and treated with three dose-regimens of Dicyclopentadienyldichlorotitanium (IV) (DDCT). We also: studied the presence of colony stimulating factors In the serum of PDCT-treated animals as well-as the effects-of the drug on the survival of the tumor-bearing mice. The-results demonstrated that the myelosuppression developed in the tumor-bearing animals is prevented by the administration:of 1, 2 or 3 doses of 15 mg/kg DDCT. In the treatment with three doses, however, 23 % of the animals died. Moreover, DDCT treatment in normal animals resulted in increased numbers of CFU-GM. We observed the presence of stimulating factors in the serum of drug-treated animals which induced the growth and differentiation of bone marrow progenitor cells from normal animals in vitro. on the other hand, in vitro addition of the drug to these cultures had no effect. Thus, we conclude that the drug protects against the myelosuppression induced by the tumor and that this protection may be related to an indirect action of the drug. (C) 1998 International Society for Immunopharmacology. Published by Elsevier B.V. Ltd.
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Drosophila serido is considered to be a superspecies consisting of two species: D. serido, from Brazil and D. koepferae from Argentina and Bolivia. However this probably does not express the entire evolutionary complexity of its populations. Isofemale lines A95F3 (from Brazil) and B20D2 (from Argentina), at present representing, respectively, the first and second species, were analyzed for fertility and fecundity in pair-mating intracrosses and intercrosses, as well as for development time, banding patterns and asynapsis of polytene chromosomes in the isofemale lines and their hybrids.Although variations in experimental conditions resulted in some variability in the results, in general A95F3 fertility and fecundity were lower than in B20D2. Intercrosses of A95F3 females and B20D2 males showed lower fertility and fecundity than the reciprocal crosses, following more closely characteristics of the mother strains. This is in contrast to the results obtained by Fontdevilla et al. (An. Entomol. Soc. Amer. 81: 380-385, 1988) and may be due to the different geographic origin of D. serido strains they used in crosses to B20D2. This difference and others cited in the literature relative to aedeagus morphology, karyotype characteristics, inversion polymorphisms and reproductive isolation strongly indicate that A95F3 and D. serido from the State of Bahia, Brazil are not a single evolutionary entity, reinforcing the idea of greater complexity of the superspecies D. serido than is known today.The reproductive isolation mechanisms found operating between A95F3 and B20D2 were prezygotic and postzygotic, the latter included mortality at the larvae stage in both directions of crosses and sterility of male hybrids in intercrosses involving B20D2 females and A95F3 males. The two isofemale lines differed in egg-adult development time, which was also differently affected by culture medium composition.A95F3 and B20D2 also showed differences in the banding patterns of proximal regions of polytene chromosomes 2, 3 and X, a fixed inversion in chromosome 3 (here named 3t), apparently not described previously, and a high degree of asynapsis in hybrids.These observations, especially those related to reproductive isolation and chromosomal differentiation (including the karyotype, previously described, and the differentiation of banding patterns, described in this paper), as well as the extensive asynapsis observed in hybrids reinforces the distinct species status of A95F3 and B20D2 isofemale lines.
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Ruthenium(II) complexes with general formula [RuCl3(NO)(P-P)] were obtained in the solid state, where P-P = PPh(2)(CH2)(n)PPh(2) (n = 1-3) and PPh(2)-CH = CH-PPh(2). The P-31 NMR spectra of these compounds measured in CH2Cl2 showed only singlets, consistent with a fac configuration containing two equivalent phosphorus atoms, However the X-ray diffraction data show that the [RuCl3(NO){PPh(2)(CH2)(3)PPh(2)}] complex crystallizes in a met configuration, where one of the phosphorus atoms is trans to the NO group, in a slightly distorted octahedral geometry. Copyright (C) 1996 Elsevier B.V. Ltd
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We tested the hypothesis that a panel of antibodies to cell surface, cytoplasmic, and nuclear antigens could reliably distinguish the cells composing reactive germinal centers from those composing follicular lymphoma. Immunocytochemistry was performed on deparaffinized sections of methacarn-fixed lymph node and tonsil (15 cases of reactive hyperplasia and 14 cases of follicular lymphoma) using antibodies to the nerve growth factor receptor (NGFR5), bcl-2 protein (124), proliferating cell nuclear antigen (PCNA; 19A2), and CD45RA (MT2). In 100% of cases of reactive hyperplasia, both MT2 and 124 showed positive immunostaining of mantle zone and scattered interfollicular lymphocytes, but in all cases there was a sharply demarcated absence of immunostaining of germinal center cells. However, diffuse immunostaining of follicular centers with MT2 (64%) and 124 (93%) and scattered intervening cells were seen in follicular lymphoma. The combination of antibodies to CD45RA and bcl-2 yielded positive immunostaining of follicular center cells in 93% of follicular lymphomas. The germinal center cells of reactive hyperplasia showed >75% nuclear positivity with antibodies to PCNA, in contrast to the follicular lymphoma cells, which showed variable PCNA indices ranging from 25 to >75%. A minority of follicular lymphoma cases (29%) showed PCNA indices comparable with those seen in cases of reactive hyperplasia. Antibodies to NGFR were positive in all cases of reactive hyperplasia and in 79% of cases of follicular hyperplasia, although the immunostaining intensity was generally decreased in follicular hyperplasia. In summary, antibodies to bcl-2 appear to be superior to those to CD45RA in distinguishing reactive hyperplasia from follicular lymphoma. Reactive hyperplasia cannot be discriminated from follicular hyperplasia using antibodies to PCNA or to nerve growth factor receptor.
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The present work deals with the ultrastructure of the haemocytes present in the dorsal thoracic region of larvae and pre-pupae of Melipona quadrifasciata anthidioides. This is a region of intense muscular differentiation in this phase of life of the insect. Only plasmatocytes, granulocytes, and adiphoaemocytes were found in this area, all showing signs of being intermediate forms.
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There has been persistent controversy regarding the nature of cell differentiation in alveolar soft-part sarcoma (ASPS) since its first description in 1952. Some studies suggest that ASPS might represent an unusual variant of skeletal muscle tumor, Given the availability of new monoclonal antibodies to probe for skeletal muscle differentiation and the rapid advance in immunocytochemical techniques for deparaffinized, formalin-fixed tissue sections, we wished to test the proposed hypothesis that ASPS might represent a new type of rhabdomyosarcoma Twelve archival samples of ASPS were retrieved, and we investigated the expression of two myogenic regulatory proteins, MyoD1 and myogenin, as rvell as other muscle-associated proteins, using sensitive immunocytochemical techniques. Despite the presence of desmin immunostaining in six ASPSs, no tumors were positive for either muscle actin or myoglobin Most importantly, no specimen showed nuclear expression of MyoD1 or myogenin, In 11 tumors, however, there was considerable granular immunostaining in the tumor cell cytoplasm with the anti-MyoD1 monoclonal antibody 5.8A, a phenomenon observed in various nonmuscle normal and neoplastic tissues with this antibody, To analyze the exact nature of immunostaining of MyoD1 and desmin in ASPS, biochemical analyses using available fresh frozen tumor tissue were performed, Although a 53-kDa band was noted with antidesmin antibody on Western blot analysis, no specific protein band that corresponds to the 45-kDa MyoD1 was detected with antibody 5.8A. These results confirm the presence of desmin in ASPS but argue against authentic expression of MyoD1, They also suggest that the cytoplasmic immunostaining observed with anti-MyoD1 antibody 5.8A most likely represents a nonspecific cross-reaction with an unknown cytoplasmic antigen, Considering the master role that MyoD1 and myogenin play in skeletal muscle commitment and differentiation and the lack of expression of these two proteins in ASPS as determined immunocytochemically and biochemically, we think that the histogenesis of ASPS remains unknown.
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Theory recently developed to construct confidence regions based on the parametric bootstrap is applied to add inferential information to graphical displays of sample centroids in canonical variate analysis. Problems of morphometric differentiation among subspecies and species are addressed using numerical resampling procedures.
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Specimens of Hyla nana and Hyla sanborni from a syntopic population were studied cytogenetically. These species are morphologically very similar and are frequently misidentified, confused with each other. Both species had a diploid chromosome number, 2n = 30. However, the karyotypes of H. nana and H. sanborni differed considerably from each other in the number of submetacentric and telocentric chromosomes. The two species also differed in their primary NOR-bearing chromosomes (metacentric pair 13 in H. nana and telocentric pair 12 in H. sanborni). Additional nucleolus organizer regions (NORs) were detected by Ag-NOR staining and FISH in chromosome pairs 1, 5, 6, 12, and 14 in seven specimens of H. nana. Thus, a total of six patterns of NOR were identified. These differences in karyotype and in NOR location allowed the unambiguous identification of syntopic individuals of the two species. However, the chromosomal morphology of both species differed from that reported for populations from other geographic regions, suggesting that a systematic reevaluation of this group of Hyla may be necessary.
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In insects the antennal lobes (AL) constitute the brain deutocerebrum. In bees they consist of two neuropil regions, each associated with one antenna, delimited by a layer of glial cells and somata of neurons. The neuropil is organized in distinct globular structures of dense synaptic axons coming from the olfactory organs of the antennae, known as glomeruli. In Apis mellifera, as in other eusocial species of bees, queens, workers, and drones perform different functions in the colony and consequently the organs associated with these functions undergo a differential development. In this paper we analyzed the structure and size of the differentiating AL of queens, workers, and drones during metamorphosis using light microscopy. During metamorphosis the neuropil enlarge and differentiates into concentric structures known as glomeruli. The results showed size, structural and temporal differences in the glomeruli development among the classes of individuals of the colony. The neuropil differentiation starts early and is faster in drones and newly emerged worker is the colony individual class with greater neuropil area in AL. These results are discussed taking in account the functions of the individuals in the colony. (C) Koninklijke Brill NV, Leiden, 2011.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)