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11.
Based on a review of current literature and recommendations, the American College of Preventive Medicine presents a practice policy statement on perimenopausal hormone replacement therapy. 相似文献
12.
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
13.
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
14.
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
15.
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
16.
患者,女,62岁,因颈部肿块就诊。既往32年前因胆囊疾病行胆囊切除术。15年前因多发性甲状腺结节行甲状腺次全切除术,病理结果为小灶性甲状腺癌。10年前因血尿诊断为肾癌,行右肾切除术。.体格检查:锁骨上可触及一5.0cm×3.0cm大小肿块(穿刺细胞学检查结果不能定性)。.辅助检验:腹 相似文献
17.
18.
Aamir Lal Eui-Joon Kil Thuy T. B. Vo I Gusti Ngurah Prabu Wira Sanjaya Muhammad Amir Qureshi Bupi Nattanong Muhammad Ali Malik Nawaz Shuja Sukchan Lee 《Viruses》2022,14(10)
Recombination between isolates of different virus species has been known to be one of the sources of speciation. Weeds serve as mixing vessels for begomoviruses, infecting a wide range of economically important plants, thereby facilitating recombination. Chenopodium album is an economically important weed spread worldwide. Here, we present the molecular characterization of a novel recombinant begomovirus identified from C. album in Lahore, Pakistan. The complete DNA- A genome of the virus associated with the leaf distortion occurred in the infected C. album plants was cloned and sequenced. DNA sequence analysis showed that the nucleotide sequence of the virus shared 93% identity with those of the rose leaf curl virus and the duranta leaf curl virus. Interestingly, this newly identified virus is composed of open reading frames (ORFs) from different origins. Phylogenetic networks and complementary recombination detection methods revealed extensive recombination among the sequences. The infectious clone of the newly detected virus was found to be fully infectious in C. album and Nicotiana benthamiana as the viral DNA was successfully reconstituted from systemically infected tissues of inoculated plants, thus fulfilling Koch’s postulates. Our study reveals a new speciation of an emergent ssDNA plant virus associated with C. album through recombination and therefore, proposed the tentative name ‘Chenopodium leaf distortion virus’ (CLDV). 相似文献
19.
羊肚菌Morchella esculenta是子囊菌亚门的一种大型药食两用真菌,具有重要的经济价值和药用价值。然而近年来全球气候变化,导致羊肚菌属物种的栖息地破碎和片段化,加上消费者对羊肚菌美食的喜爱,过渡采挖造成羊肚菌属野生资源急剧减少,因此,急需对羊肚菌属物种资源进行保护。遗传多样性的时空分布是保护生物学的重要内容,遗传多样性关系到一个物种或类群的进化潜力和未来命运。生物基因组和进化的研究能够辅助挖掘物种深层次的优异基因资源,有利于从本质上对物种进行科学保护。从羊肚菌属的遗传多样性、遗传结构和家系关系以及基因组进化等的研究进展进行综述,以期为羊肚菌属资源的科学保护提供重要依据。 相似文献
20.
丁香水溶性化学成分的研究 总被引:2,自引:0,他引:2
目的:研究丁香水溶性化学成分。方法:利用HP-20大孔吸附树脂、反相硅胶柱色谱、反相制备薄层色谱、制备型反相高效液相色谱进行分离,NMR和MS等方法进行结构鉴定。结果:从丁香干燥花蕾的水提物中分离鉴定了5个化合物,分别为槲皮素-3-O-葡萄糖醛酸苷(1),槲皮素-3-O-葡萄糖醛酸苷6″-甲酯(2),槲皮素-3-O-葡萄糖苷(3),丁香酚-β-芸香糖苷(4),杨梅酮(5)。结论:化合物1~4为首次从丁香属植物中分离得到。 相似文献