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51.
Since exogenous hemin has been shown to exert a variety of stimulatory effects on erythroid cells, including the augmentation of hemoglobin synthesis, we determined its effect on early stages of erythroid development by employing clonal cells assays. The addition of hemin at a concentration of 2 X 10(-4) M to cultures of normal murine marrow substantially increased the observed number of primitive BFU-E, which was in contrast to its lack of an effect on more mature erythroid colony-forming cells. This cell-specific enhancement of primitive BFU-E resulted in marrow frequencies equivalent to or exceeding those reported in the presence of "burst-promoting activity." In the presence of hemin, the number of BFU-E was also observed to be linearly related to the number of cells plated at very low plating densities, and the cell titration curve was observed to extrapolate to the origin. The evidence suggests that hemin may be a primary growth regulator of early developmental stages of erythroid progenitor cells. 相似文献
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53.
Scientific validation of two commercial pressure sensor systems for prosthetic socket fit 总被引:1,自引:0,他引:1
Polliack AA Sieh RC Craig DD Landsberger S McNeil DR Ayyappa E 《Prosthetics and orthotics international》2000,24(1):63-73
The concept of measuring pressure at the interface between the stump and the prosthetic socket could provide valuable information in the process of prosthetic socket fabrication, modification, and fit. Two systems, the Rincoe Socket Fitting System (SFS) and Tekscan's F-Socket Pressure Measurement System, have been commercially designed for in situ interface pressure measurement over the past decade. Their use is not common in prosthetic practice, perhaps due to questions of cost effectiveness and the difficulties of interpreting the data. Another concern is the use of sensors for pressure measurements in areas of high contour and complex geometries such as the stump. Before these systems can be used in a clinical setting, it is necessary to determine the reliability and accuracy of each system. In order to assess the clinical validity of the Rincoe SFS and F-Socket systems, a series of trials was conducted to evaluate different aspects of sensor performance, namely; accuracy, hysteresis, drift and the effect of curvature. The sensors were subjected to tests in flatbed and custom-designed pressure vessels. Overall results indicated an accuracy error for the Rincoe SFS system of 25% (flatbed) and 33% (mould), with a corresponding 15% (flatbed) and 23% (mould) error in hysteresis, and 7% (flatbed) and 11% (mould) drift errors. The F-Socket system demonstrated an 8% (flatbed) and 11% (mould) accuracy errors, 42% (flatbed) and 24% (mould) hysteresis errors, and 12% (flatbed) and 33% (mould) drift errors. These findings indicate favourable results for the F-Socket Pressure Measurement System compared to the Rincoe Socket Fitting System with respect to its accuracy errors only. Nevertheless, it is the authors' belief that these systems are adequate in indicating areas of high pressure at the stump socket interface for clinical purposes, but both systems should be used with caution. 相似文献
54.
Assessment of the mutagenicity of dichloroacetic acid in lacI transgenic B6C3F1 mouse liver 总被引:2,自引:0,他引:2
Dichloroacetic acid (DCA) is a chlorination byproduct found in finished
drinking water. When administered in drinking water this chemical has been
shown to produce hepatocellular adenomas and carcinomas in B6C3F1 mice over
the animal's lifetime. In this study, we investigated whether mutant
frequencies were increased in mouse liver using treatment protocols that
yielded significant tumor induction. DCA was administered continuously at
either 1.0 or 3.5 g/l in drinking water to male transgenic B6C3F1 mice
harboring the bacterial lacI gene. Groups of five or six animals were
killed at 4, 10 or 60 weeks and livers removed. At both 4 and 10 weeks of
treatment, there was no significant difference in mutant frequency between
the treated and control animals at either dose level. At 60 weeks, mice
treated with 1.0 g/l DCA showed a 1.3-fold increase in mutant frequency
over concurrent controls (P = 0.05). Mice treated with 3.5 g/l DCA for 60
weeks had a 2.3-fold increase in mutant frequency over the concurrent
controls (P = 0.002). The mutation spectrum recovered from mice treated
with 3.5 g/l DCA for 60 weeks contained G:C-->A:T transitions (32.79%)
and G:C-->T:A transversions (21.31%). In contrast, G:C-->A:T
transitions comprised 53.19% of the recovered mutants among control
animals. Although only 19.15% of mutations among the controls were at T:A
sites, 32.79% of the mutations from DCA-treated animals were at T:A sites.
This is consistent with the previous observation that the proportion of
mutations at T:A sites in codon 61 of the H-ras gene was increased in
DCA-induced liver tumors in B6C3F1 mice. The present study demonstrates
DCA-associated mutagenicity in the mouse liver under conditions in which
DCA produces hepatic tumors.
相似文献
55.
Fatty acid balance studies in term infants fed formula milk containing long-chain polyunsaturated fatty acids 总被引:1,自引:0,他引:1
C Morgan L Davies F Corcoran J Stammers J Colley SA Spencer D Hull 《Acta paediatrica (Oslo, Norway : 1992)》1998,87(2):136-142
Long-chain polyunsaturated fatty acids (LCP) are thought to be required for optimal nervous system development in the newborn. A commercial milk formula containing LCP (Aptamil-LCP) with a fatty acid profile closely resembling breast milk, has recently been introduced for term infants. The absorption of fatty acids in term infants was examined in a double-blind randomized controlled trial comparing Aptamil-LCP ( n = 20) and standard Aptamil ( n = 20). Formula-fed newborn infants were studied from birth for 14 d. Fat balances (3 d) were performed from d 10. A 3-d stool collection was performed from d 10 in a parallel breastfed group ( n = 21). Plasma samples were taken on d 6. Median fat excretion (mg kg−1 ) was 897.1, 615.0 and 355.2 with Aptamil, Aptamil-LCP and breastfeeding, respectively. The median total fat absorption coefficient in Aptamil-LCP-fed infants was higher than in those fed standard Aptamil ( p < 0:01). These findings were accounted for by differences in the excretion and absorption of long-chain saturated fatty acids (C14:0, C16:0 and C18:0). Higher fat excretion was associated with bulkier and firmer stools. Only trace amounts of LCP were detected in the stools of all groups. This accounted for less than 4% of dietary intake in Aptamil-LCP-fed infants. No differences in the utilization of LCP from Aptamil-LCP and breast milk feeding were apparent. Plasma phospholipid fatty acid composition data reflected differences in dietary LCP intake. Thus, PL LCP levels were highest in the breastfed infants and lowest in the Aptamil-fed infants, with values for the Aptamil-LCP-fed group falling in between. 相似文献
56.
Characterization of the insulin-like growth factor axis in a human hepatoma cell line (PLC) 总被引:4,自引:0,他引:4
Scharf JG; Schmidt-Sandte W; Pahernik SA; Ramadori G; Braulke T; Hartmann H 《Carcinogenesis》1998,19(12):2121-2128
57.
58.
Linda Dodds Noni MacDonald Jeffrey Scott Anne Spencer Victoria M. Allen Shelly McNeil 《Journal d'obstetrique et gynecologie du Canada》2012,34(8):714-720
ObjectiveTo determine whether neonatal outcomes differ between women vaccinated during pregnancy and those not vaccinated.MethodsSelf-reported history of receipt of influenza vaccination during pregnancy was collected from women at the time of admission for obstetrical delivery at the IWK Health Centre in Halifax, Nova Scotia, beginning in April 2006. The cohort for this study included women who delivered a singleton infant prior to November 2009, reflecting the pre-pandemic H1N1 vaccination period. Neonatal outcomes were compared using logistic regression between vaccinated and non-vaccinated women.ResultsOverall, 1957 of 9781 women (20%) included in the cohort received influenza vaccine during their pregnancy. The adjusted odds ratio and 95% confidence interval for a small for gestational age infant (lowest 10th percentile birth weight for gestational age and sex) was 0.80 (95% CI 0.65 to 0.95) for vaccinated women relative to non-vaccinated women. The adjusted odds ratio for a low birth weight infant was 0.74 (95% CI 0.58 to 0.95). Rates of preterm birth and a composite indicator of adverse neonatal outcomes were lower among vaccinated women, but were not statistically significant. The effects of maternal vaccination on neonatal outcomes did not differ between high- and low-risk women.ConclusionAs evidence continues to mount in support of improved neonatal outcomes associated with receiving influenza vaccination during pregnancy, enhanced public health measures are necessary to encourage pregnant women to receive the influenza vaccine. 相似文献
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60.