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81.
82.
Triploidies are pregnancies that show a 69 chromosome karyotype. This chromosomal abnormality gives rise to early abortion in most cases. Triploid pregnancies, after the first three months, become molar pregnancies (molar changes inside the placenta with identifiable embryonic structures and a preeclampsia) or non molar pregnancies (isolated intauterin growth retardation). Several possibilities concerning the origin of the additional set of chromosomes exist: dispermy (the most common), diandry and digyny. The maternal and fetal clinical manifestations of this chromosomal abnormality are very diverse, which explains the difficulty of finding and recognizing this pathology. Mac Fadden's classification does not explain all the phenotypic triploid physiopathology. Formal diagnosis of triploidy depends on the fetal karyotype. The better the maternal prognosis is, the worst the fetal prognosis is. Postnatal life expectancy is not more than a few weeks. In most cases, maternal associated complications disappear with the molar evacuation. The risk of post molar tumor is discussed. However, good management of triploidy is based on an early diagnosis, before birth if that is possible. 相似文献
83.
This paper discusses recent trends in the field of reverse engineering, particularly those highlighted at the Second Working Conference on Reverse Engineering, held in July 1995. The trends observed include increased orientation toward tasks, grounding in complex real-world applications, guidance from empirical study, analysis of non-code sources, and increased formalization. The paper also summarizes open research issues and provides pointers to future events and sources of information in this area. 相似文献
84.
R Clynes Y Takechi Y Moroi A Houghton JV Ravetch 《Canadian Metallurgical Quarterly》1998,95(2):652-656
Effective tumor immunity requires recognition of tumor cells coupled with the activation of host effector responses. Fc receptor (FcR) gamma-/- mice, which lack the activating Fc gamma R types I and III, did not demonstrate protective tumor immunity in models of passive and active immunization against a relevant tumor differentiation antigen, the brown locus protein gp75. In wild-type mice, passive immunization with mAb against gp75 or active immunization against gp75 prevented the development of lung metastases. This protective response was completely abolished in FcR gamma-deficient mice. Immune responses were intact in gamma-/- mice because IgG titers against gp75 develop normally in gamma-/- mice immunized with gp75. However, uncoupling of the Fc gamma R effector pathway from antibody recognition of tumor antigens resulted in a loss of protection against tumor challenge. These data demonstrate an unexpected and critical role for FcRs in mediating tumor cytotoxicity in vivo and suggest that enhancement of Fc gamma R-mediated antibody-dependent cellular cytotoxicity by inflammatory cells is a key step in the development of effective tumor immunotherapeutics. 相似文献
85.
WG Young JV Ruch MR Stevens C Bègue-Kirn CZ Zhang H Lesot MJ Waters 《Canadian Metallurgical Quarterly》1995,40(9):789-799
The effects of growth hormone, its mediator insulin-like growth factor-I (IGF-I), and fetal calf serum on odontogenesis were compared to those of serum-free medium. Explanted, 16-day, fetal mouse first molar tooth germs in early bell stage were grown on semisolid, serum-free medium supplemented with ascorbic and retinoic acids. Recombinant human growth hormone at 50 or 100 ng/ml, IGF-I at 100 or 200 ng/ml, or fatal calf serum at 20% concentration were added to the media. Volumetric changes in serial sections of six tooth germs per treatment over 3 days of treatment (4, 5, 6 days in vitro) were compared by digitized morphometry. Mitotic indices were also compared and the cell densities of the dental papillae recorded. Qualitative ratings of differentiation were ascribed to each tooth germ by light microscopy. Differences in volume, mitotic activity and cell densities were found. The growth hormone-treated tooth germs were not larger than the serum-free ones but had increased mitotic indices and higher cell densities in the dental papillae. IGF-I-treated tooth germs had larger volumes than with all other treatments, e.g. germs treated with 200 ng/ml of IGF-I, after 6 days in culture, were significantly larger than with all other treatments (p<0.01-<0.001). Whilst IGF-I-treated germs displayed the greatest extent of differentiation, growth hormone-treated germs also showed advanced differentiation compared to those on serum-free medium. These results suggest that growth hormone and IGF-I are involved in odontogenesis of murine teeth in vitro by affecting mitotic activity, tissue volume and cell differentiation. In conjunction with previous immunohistochemical studies that show expression of growth hormone receptor and IGF-I in developing teeth, these results provide evidence that both growth hormones and its mediator play a part in odontogenesis. 相似文献
86.
Attic dust and soil samples were collected during the Summer of 1996 and the Spring of 1997 in southern Nevada and southern Utah. Analysis of the samples for radiocesium and plutonium give activity ratios of radiocesium/plutonium that range from 0.7 +/- 0.1 to 27 +/- 2, well below the world-wide fallout ratio of 34 +/- 4 (as of 1 July 1997). This indicates anomalous plutonium throughout the region, including areas to the south of the Nevada Test Site (NTS), generally believed to have received only world-wide fallout. Safety tests and above-ground detonations that resulted in incomplete fission, conducted at the NTS during the 1950's and 1960's, are likely sources of this excess plutonium. 相似文献
87.
E Solsona I Iborra JV Ricós JL Monrós R Dumont S Almenar 《Canadian Metallurgical Quarterly》1996,155(3):895-9; discussion 899-900
PURPOSE: The biological and therapeutic implications of extravesical involvement in patients with bladder carcinoma in situ were analyzed. MATERIALS AND METHODS: Of 138 patients with bladder carcinoma in situ 87 (63%) had extravesical involvement, including the prostate in 53, the upper urinary tract in 11 and both structures in 23 (pan-urothelial involvement). With survival free of disease as an end point, univariate and multivariate analyses were done. RESULTS: Patients with extravesical involvement had worse survival than those with bladder carcinoma in situ alone (p < 0.001). In multivariate analysis prostate involvement (p = 0.0007) and pan-urothelial involvement (p = 0.0001) were selected as significant variables. When pathological patterns were considered prostatic stromal invasion (p = 0.0002) was the only variable selected. With these data 3 patient groups with disease mortality risk were defined. CONCLUSIONS: Prostate involvement and pan-urothelial involvement behave as independent prognostic factors, with the latter probably reflecting an extremetly diffuse character of carcinoma in situ. However, the upper urinary tract had no influence on survival. In patients with upper urinary tract and/or prostatic involvement limited to the mucosa treatment can be conservative. Patients with ductal or stromal involvement should undergo radical treatment. For upper tract involvement conservative approaches may be considered if there are no radiological signs of invasion or low grade tumor. 相似文献
88.
The spindle pole body (SPB) is the microtubule organizing center (MTOC) in the yeast Saccharomyces that plays a pivotal role in such diverse processes as mitosis, budding, and mating. We have used cryoelectron microscopy and image processing to study the structure of isolated diploid SPBs. We show that SPBs are present in two lateral-size classes, sharing a similar vertical architecture comprised of six major layers. Tomographic reconstructions of heparin-stripped SPBs reveal a central hexagonally packed layer. Overexpression of Spc42p results in the growth of a similar layer, forming a crystal that encircles the SPB. Hence, the SPB is an MTOC that utilizes crystallographic packing of subunits in its construction. 相似文献
89.
N. S. Ginzburg Yu. V. Novozhilova I. V. Zotova A. S. Sergeev A. D. R. Phelps A. W. Cross S. M. Wiggins V. Khi K. Ronald V. G. Shpak M. I. Yalandin S. A. Shunailov M. R. Ul’maskulov V. P. Tarakanov 《Technical Physics Letters》1998,24(9):709-711
The generation of ultrashort microwave pulses was observed experimentally in the superradiance of high-current electron bunches
propagating through a periodic slow-wave structure. The process included particle bunching within the bunch followed by coherent
emission from the entire volume of the bunch.
Pis’ma Zh. Tekh. Fiz. 24, 7–13 (September 26, 1998) 相似文献
90.
Human calcitonin (hCT) has been reported to have a less hypocalcemizing effect on rats and to have a lower binding affinity for the receptor of mouse osteoclasts than salmon CT(sCT). In this study we comparatively examined the effect of hCT and sCT on osteoclastic bone-resorbing activity of unfractionated cells obtained from human giant cell tumor of bone and from rabbit and mouse long bones. We found that hCT had the same inhibitory effect as sCT on the bone-resorbing activity of human and rabbit osteoclastic cells, but a different one on that of mouse cells. These results indicate that the activity of drugs should be assayed using human cells if possible. 相似文献