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61.
62.
Extracellular matrix vesicles (MVs) are associated with initial calcification in a variety of tissues, but the mechanisms
by which they promote mineralization are not certain. In this study, MVs isolated from fourth passage rat growth plate chondrocyte
cultures were included within a gelatin gel into which calcium and phosphate ions diffused from opposite ends. In this gel,
apatite formation occurs by 3.5 days in the absence of mineralization promoters, allowing measurement of the ability of different
factors to ``nucleate' apatite before this time or to assess the effects of molecules which modulate the rate and extent
of mineral deposition. Mineral ion accumulation and crystal type are assayed at 5 days. In this study, MV protein content
in the central band of a 10% gelatin gel was varied by including 100 μl of a Tris-buffered solution containing 0–300 μg/ml
MV protein. There was a concentration-dependent increase in mineral accretion. Whereas 10 μg MV protein in the gel did not
significantly promote apatite formation as compared with vesicle-free gels, 20 and 30 μg MV protein in the gel did promote
apatite deposition. Inclusion of 10 mM β-glycerophosphate in the gels, along with MVs, did not significantly increase apatite
formation despite the demonstrable alkaline phosphatase activity of the MVs. In contrast, MVs at all concentrations significantly
increased apatite accumulation when proteoglycan aggregates or ATP, inhibitors of apatite formation and proliferation, were
included in the gel. Slight increases in calcium, but not phosphate accumulation, were also noted when an ionophore was included
with the MVs to facilitate Ca ion transport into the vesicles. FT-IR analysis of the mineral formed in the vesicle-containing
gels revealed the presence of a bone-like apatite. These data suggest that MVs facilitate mineralization by providing enzymes
that modify inhibitory factors in the extracellular matrix, as well as by providing a protected environment in which mineral
ions can accumulate.
Received: 28 January 1996 / Accepted: 9 August 1996 相似文献
63.
Screening for early ovarian cancer 总被引:5,自引:0,他引:5
64.
Background: Percutaneous closed needle biopsy of musculoskeletal neoplasms has gained in popularity. However, it remains controversial
whether or not to resect the needle tract for fear of a local recurrence. A single published case report exists, noting the
lone tract recurrence of an extremity skeletal osteosarcoma.
Methods: We report on three additional individuals who demonstrated that tract local recurrences may occur after a closed needle biopsy
for nonosteosarcoma, nonextremity sarcomas. For perspective, the world literature is reviewed to identify tract recurrences
for other malignancies and the results of needle biopsy in musculoskeletal neoplasms.
Results: Eighty-nine percent of needle tract local recurrences occur when carcinomas are subjected to biopsy, as reported in the literature.
Forty-seven cases since 1950 are described representing essentially all tumor types. The nature of musculoskeletal neoplasms
makes closed biopsy more difficult than for softer, more homogeneous, and easier to access neoplasms.
Conclusions: Local recurrences of sarcoma may occur in closed needle biopsy tracts. Strong consideration should be given to open biopsy
and tract resection. 相似文献
65.
Brain neurons and glial cells express Neu differentiation factor/heregulin: a survival factor for astrocytes. 总被引:8,自引:1,他引:7 下载免费PDF全文
R Pinkas-Kramarski R Eilam O Spiegler S Lavi N Liu D Chang D Wen M Schwartz Y Yarden 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(20):9387-9391
Neu differentiation factor (NDF, also called heregulin) was isolated from mesenchymal cells on the basis of its ability to elevate phosphorylation of ErbB proteins. Earlier in situ hybridization analysis showed that NDF was transcribed predominantly in the central nervous system during embryonic development. To gain insights into the role of NDF in brain we analyzed its distribution by immunohistochemistry and in situ hybridization. Late-gestation (day 17) rat embryos displayed high NDF immunoreactivity in both motor (e.g., putamen) and limbic (e.g., septum) regions. Lower levels of the factor were exhibited by adult brain, except for the cerebellum, where NDF expression was increased postnatally. Both neurons and glial cells were identified by immunohistochemistry as NDF-producing cells (e.g., pyramidal neurons in the cerebral cortex and glial cells in the corpus callosum). By establishment of primary cultures of rat brain cells we confirmed that NDF was expressed in neurons as well as in astrocytes. In addition, by using such primary cultures we observed that NDF treatment exerted only a limited mitogenic effect, which was accompanied by significant acceleration of astrocyte maturation. Furthermore, long-term incubation with the factor specifically protected astrocytes from apoptosis, implying that NDF functions in brain as a survival and maturation factor for astrocytes. 相似文献
66.
D A Schwartz L A Newsum R M Heifetz 《Scandinavian journal of work, environment & health》1986,12(1):51-54
The general birth outcome and prevalence of specific birth defects was investigated within an agricultural community through the review of birth records in a major hospital in Imperial County, California. Of all singleton births (N = 2 463) occurring within a four-year period, 990 or 40.2% involved offspring with one or both parent(s) who were agricultural workers. The progeny of agricultural and nonagricultural workers were similar with regard to sex ratios, prevalence of low birth-weight infants, stillbirth rate, minor and major malformation rates, and prevalence of neonatal deaths. Limb reduction defects, however, occurred more frequently among offspring of agricultural workers (5.05 per 1 000 total births versus 2.19 per 1 000 total births, rate ratio = 2.3). Furthermore, the prevalence of limb reduction defects among agricultural workers was 3- to 14-fold higher than available United States rates (0.36-1.65 per 1 000 total births). Findings from our study suggest that agricultural communities and, in particular, agricultural workers may be at excess risk of producing a child with a limb reduction defect. 相似文献
67.
Using 600 clinical specimens, we compared the concordance of four methods for carcinoembryonic antigen: the Roche RIA (I); the Roche EIA (II); Hybritech EIA (III); and Abbott EIA (IV). EDTA-treated plasma was used for Methods I and II and serum for Methods III and IV. However, no significant difference was found between results for serum and plasma in Method II. The normal reference interval (in micrograms/L) was I (222 specimens), 1.94 +/- 1.54; II (57 specimens), 0.8 +/- 0.5; III (100 specimens), 2.94 +/- 2.47; and IV (614 specimens), less than 5.0. The precision of all four methods was acceptable. Concordance among all of the methods exceeded 90%. 相似文献
68.
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