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1.
Effect of dietary cis and trans fatty acids on serum lipoprotein[a] levels in humans. 总被引:4,自引:0,他引:4
Serum lipoprotein[a] (Lp[a]) is a strong risk factor for coronary heart disease. We therefore examined the effect of dietary fatty acid composition on serum Lp[a] levels in three strictly controlled experiments with healthy normocholesterolemic men and women. In Expt. I, 58 subjects consumed a control diet high in saturated fatty acids for 17 days. For the next 36 days, 6.5% of total energy intake from saturated fatty acids was replaced by monounsaturates plus polyunsaturates (monounsaturated fatty acid diet; n = 29) or by polyunsaturates alone (polyunsaturated fatty acid diet; n = 29). Both diets caused a slight, nonsignificant, increase in median Lp[a] levels, with no difference between diets. In Expt. II, 10% of energy from the cholesterol-raising saturated fatty acids (lauric, myristic, and palmitic acid) was replaced by oleic acid or by trans-monounsaturated fatty acids. Each of the 59 participants received each diet for 3 weeks in random order. The median level of Lp[a] was 26 mg/l on the saturated fatty acid diet; it increased to 32 mg/l (P less than 0.020) on the oleic acid diet and to 45 mg/l (P less than 0.001) on the trans-fatty acid diet. The difference in Lp[a] between the trans-fatty acid and the oleic acid diets was also highly significant (P less than 0.001). Expt. III involved 56 subjects; all received 8% of energy from stearic acid, from linoleic acid, or from trans-monounsaturates, for 3 weeks each. All other nutrients were equal.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Specificity of RepC protein in plasmid pT181 DNA replication 总被引:6,自引:0,他引:6
The plasmid pT181 of Staphylococcus aureus consists of 4437 base pairs and encodes resistance to tetracycline. Initiation of pT181 DNA replication specifically requires the plasmid-encoded initiator protein, RepC. The initiator protein binds specifically to a 32-base pair sequence within the pT181 origin of replication. RepC protein also has a nicking-closing activity that is specific for the pT181 origin. Replication of pT181 initiates by covalent extension of the nick and proceeds by a rolling circle mechanism. Two other small, multicopy plasmids pC221 and pS194 belong to the pT181 family and have common structural organization and replication properties. The replication proteins and replication origins of these plasmids have extensive sequence homologies, although they belong to different incompatibility groups. In spite of this homology, the replication proteins and replication origins of these three plasmids do not show any cross-reactivity in vivo. We have carried out a series of in vitro experiments to determine the specificity of pT181-encoded initiator protein, RepC. DNA binding experiments showed that although the binding of RepC to the pT181 origin was very efficient, little or no binding was seen with pC221 and pS194 origins. The nicking-closing activity of RepC was found to be equally efficient with the pC221 and pS194 plasmids. The plasmids pC221 and pS194 replicated efficiently in a RepC-dependent in vitro system. However, replication of these plasmids was greatly reduced in the presence of a competing pT181 origin. The results presented here suggest that nicking-closing by RepC at the origin is not sufficient for maximal replication and that tight binding of RepC to the origin plays an important role in the initiation of DNA replication. 相似文献
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Maud N. Vissers Peter L. Zock Rianne Leenen Annet J.C. Roodenburg Karel P.A.M. Van Putte Martijn B. Katan 《Free radical research》2013,47(5):619-629
A high intake of olive oil has been proposed as an explanation for the low incidence of coronary heart disease in Mediterranean countries, but it is unclear whether olive oil offers specific benefits beyond a low content of saturated fat. Some types of extra virgin olive oil are rich in non-polar phenols, which might be taken up by plasma LDL particles and protect these from becoming atherogenic by oxidative modification. In a pilot study we found that consumption of 47 g fortified olive oil containing 31 mg phenols significantly increased the lag time of LDL oxidation from 112 ± 5 min before to 130 ± 7 min 2h after the meal. However, this study was not controlled, and in the current study we therefore investigated whether olive oil phenols increase the lag time of LDL oxidation in postprandial samples when compared with a control group.Twelve healthy men and women consumed four different olive oil supplements with a meal on four separate occasions: one similar to the supplement in the pilot study (positive control); one containing mainly non-polar olive oil phenols; one containing mainly polar olive oil phenols; and one without phenols (placebo). Lag time significantly increased 2 h after the meals with the positive control (8 ± 2 min), the polar phenols (8 ± 2 min), and the placebo (8 ± 2 min), but not after the non-polar phenols (-0.4 ± 3 min). Increases were not statistically different between supplements.These results indicate that the lag time of LDL-oxidation is increased after consumption of a meal. This increase is probably due to non-specific meal or time effects and not to phenols from olives or olive oil. Furthermore, these findings stress the need for adequate controlled studies to avoid misinterpretations of the data. 相似文献
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Prospective identification, isolation by flow cytometry, and in vivo self-renewal of multipotent mammalian neural crest stem cells 总被引:37,自引:0,他引:37
Multipotent and self-renewing neural stem cells have been isolated in culture, but equivalent cells have not yet been prospectively identified in neural tissue. Using cell surface markers and flow cytometry, we have isolated neural crest stem cells (NCSCs) from mammalian fetal peripheral nerve. These cells are phenotypically and functionally indistinguishable from NCSCs previously isolated by culturing embryonic neural tube explants. Moreover, in vivo BrdU labeling indicates that these stem cells self-renew in vivo. NCSCs freshly isolated from nerve tissue can be directly transplanted in vivo, where they generate both neurons and glia. These data indicate that neural stem cells persist in peripheral nerve into late gestation by undergoing self-renewal. Such persistence may explain the origins of some PNS tumors in humans. 相似文献
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S. S. Soedamah-Muthu J. M. Geleijnse E. J. Giltay J. de Goede L. M. Oude Griep E. Waterham A. M. Teitsma-Jansen B. J. M. Mulder M.-J. de Boer J. W. Deckers P. L. Zock D. Kromhout for the Alpha Omega Trial Group 《Netherlands heart journal》2012,20(3):102-109
Background
It is important to gain insight into opportunities for secondary prevention of cardiovascular disease. Our aim was to investigate levels and trends in cardiovascular risk factors and drug treatment in Dutch post-myocardial infarction (MI) patients between 2002 and 2006 and to make comparisons with the EUROASPIRE surveys (1999–2007).Methods
We analysed data from 4837 post-MI patients (aged 69 years, 78% men) from 32 Dutch hospitals, using baseline cross-sectional data from the Alpha Omega Trial.Results
Between 2002 and 2006, significant declines were found in the prevalence of smoking (23% to 16%, p < 0.001), hypercholesterolaemia (≥5 mmol/l; 54% to 27%, p < 0.0001) and hypertension (≥140/90 mmHg; 58% to 48%, p < 0.001). The prevalence of antithrombotic drugs was high (97%). The prevalence of lipid-modifying drugs and antihypertensives was high, and increased (74% to 90%, p < 0.0001 and 82% to 93%, p < 0.001, respectively). The prevalence of obesity (27%) was high in 2002 and decreased to 24% in 2006, albeit not significantly. Diabetes prevalence was high and increased between 2002 and 2006 (18% to 22%, p = 0.02). In comparison with EUROASPIRE patients, who were on average 8–10 years younger, our study in 2006 included patients with lower levels of obesity, hypertension, hypercholesterolaemia, diabetes and lower use of antiplatelets and β-blockers, but similar levels of lipid-modifying drugs.Conclusions
This study showed that older Dutch post-MI patients were adequately treated with drugs, and that risk factors reached lower levels than in the younger EUROASPIRE patients. However, there is room for improvement in diet and lifestyle, given the high prevalence of smoking, obesity, and diabetes.Electronic supplementary material
The online version of this article (doi:10.1007/s12471-012-0248-z) contains supplementary material, which is available to authorized users. 相似文献7.
Jan-Paul Flacke Sanjeev Kumar Sawa Kostin H. Peter Reusch Yury Ladilov 《Apoptosis : an international journal on programmed cell death》2009,14(1):90-96
To analyze the underlying cellular mechanisms of adaptation to ischemia-induced apoptosis through short acidic pretreatment,
i.e. acidic preconditioning (APC), Wistar rat coronary endothelial cells (EC) were exposed for 40 min to acidosis (pH 6.4)
followed by a 14 h recovery period (pH 7.4) and finally treated for 2 h with simulated in vitro ischemia (glucose-free anoxia
at pH 6.4). APC led to a transient activation of p38 and Akt kinases, but not of JNK and ERK1/2 kinases, which was accompanied
by significant reduction of the apoptotic cell number, caspase-12/-3 cleavage and Bcl-xL overexpression. These effects of
APC were completely abolished by prevention of Akt- or p38-phosphorylation during APC. Furthermore, knock-down of Bcl-xL by
siRNA-transfection also abolished the anti-apoptotic effect of APC. Therefore, APC leads to protection of EC against ischemic
apoptosis by activation of Akt and p38 followed by overexpression of Bcl-xL, which is a key anti-apoptotic mechanism of APC. 相似文献
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A J Kreuzman J M Zock J E Dotzlaf J T Vicenzi S W Queener W K Yeh 《Journal of industrial microbiology & biotechnology》1997,19(5-6):369-377
The serine hydroxymethyltransferase (SHMT) gene glyA was over-expressed in Escherichia coli and the enzyme was purified to near homogeneity. Reaction conditions for E. coli and rabbit liver SHMTs were optimized using succinic semialdehyde methyl ester (SSAME) and glycine. The catalytic efficiency
(k
cat/K
m) of E. coli SHMT for SSAME was 2.8-fold higher than that of rabbit liver enzyme. E. coli SHMT displayed a pH-dependent product distribution different from that of rabbit liver enzyme. For the pyridoxal-5′-phosphate
(PLP)-dependent reaction, E. coli and rabbit liver SHMTs showed a high product diastereospecificity. The stoichiometric ratio of PLP to the dimeric E. coli SHMT was 0.5–0.7, indicating a requirement for external PLP for maximal activity. Using SSAME or its analog at a high temperature,
E. coli SHMT mediated efficient condensation via a lactone pathway. In contrast, at a low temperature, the enzyme catalyzed efficient
conversion of 4-penten-1-al via a non-lactone mechanism. Efficient conversion of either aldehyde type to a desirable diastereospecific
product was observed at a pilot scale. E. coli SHMT exhibited a broad specificity toward aldehyde substrates; thus it can be broadly useful in chemo-enzymatic synthesis
of a chiral intermediate in the manufacture of an important carbacephem antibiotic.
Received 02 December 1996/ Accepted in revised form 24 February 1997 相似文献
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Dietary fats and cancer 总被引:6,自引:0,他引:6
Zock PL 《Current opinion in lipidology》2001,12(1):5-10
The present review addresses the evidence for a possible link between dietary fat and cancer. International comparisons suggest that a high-fat diet may increase cancer risk, and this hypothesis is supported by animal experiments. However, epidemiological studies within populations show little or inconsistent associations. Taken together, the available evidence for a relation between dietary fat and cancer is weak. 相似文献