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61.
Adrian A. Franke Cynthia M. Morrison Jesse L. Bakke Laurie J. Custer Xingnan Li Robert V. Cooney 《Free radical biology & medicine》2010,48(12):1610-1617
Coenzyme Q10 (Q10) is present in the circulation mainly in its reduced form (ubiquinol-10; UL10), but oxidizes quickly ex vivo to ubiquinone-10 (UN10). Therefore, native UL10:UN10 ratios, used as markers of redox status and disease risk, are difficult to measure. We established an RP-(U)HPLC method with coulometric detection to measure natively circulating UL10 and UN10 concentrations by adding a ubiquinol/ubiquinone mixture as an internal standard immediately after plasma preparation. This allowed adjustment for unavoidable artificial UL10 oxidation as well as for total losses (or gains) of analytes during sample storage, processing, and analysis because the internal standards exactly paralleled the chemical behavior of Q10. This technique applied to blood (n = 13) revealed Q10 levels of 680–3300 nM with a mean UL10:UN10 ratio of 95:5, which was inversely associated with total Q10 (r = ? 0.69; p = 0.004). The oxidation of UL10 to UN10 was equimolar, increased by O2, and decreased by lower temperatures or various degassing methods. Although UL10 was stable in blood or when pure in organic solvents at 22 °C, its oxidation was catalyzed dose dependently by α-tocopherol and butylated hydroxytoluene, particularly when present in combination. Key structural features for the catalytic pro-oxidant properties of phenolic antioxidants included two substituents vicinal to the phenolic hydroxyl group. 相似文献
62.
Custer JR 《Organogenesis》2011,7(1):13-22
Bill James, baseball statistician and author, tells the story of hungry cavemen sitting about a campfire, waiting for tomatoes to ripen. One has the inspiration to throw an ox on the fire, and the first barbecue ensued and was endured. After eating, the conversation goes something like this. "There were some good parts." "Yeah, but there were some bad parts." And the smart one says, "This time, let's not eat the bones." The evolution of patient selection criteria for the use of extracorporeal support (ECLS) is a bit like those cavemen and their first barbecued ox. Extracorporeal life support technology and application to patient care is the unique result of a long standing history of ambitious attempt, evaluation, debate, collaboration and extension. 相似文献
63.
McCracken JA Custer EE Schreiber DT Tsang PC Keator CS Arosh JA 《Prostaglandins & other lipid mediators》2012,97(3-4):90-96
A new in vivo model for studying luteolysis was developed in sheep to provide a convenient method for collecting corpora lutea for molecular, biochemical, and histological analysis during a procedure that mimics natural luteolysis. It was found that the infusion of prostaglandin F(2α) (PGF(2α)) at 20 μg/min/h into the systemic circulation during the mid luteal phase of the cycle allowed sufficient PGF(2α) to escape across the lungs and thus mimic the transient 40% decline in the concentration of progesterone in peripheral plasma seen at the onset of natural luteolysis in sheep. Additional 1h-long systemic infusions of PGF(2α), given at physiological intervals, indicated that two infusions were not sufficient to induce luteolysis. However, an early onset of luteolysis and estrus was induced in one out of three sheep with three infusions, two out of three sheep with four infusions, and three out of three sheep with five infusions. Reducing the duration of each systemic infusion of PGF(2α) from 1h to 30 min failed to induce luteolysis and estrus even after six systemic infusions indicating that, not only are the amplitude and frequency of PGF(2α) pulses essential for luteolysis, but the actual duration of each pulse is also critical. We conclude that a minimum of five systemic pulses of PGF(2α), given in an appropriate amount and at a physiological frequency and duration, are required to mimic luteolysis consistently in all sheep. The five pulse regimen thus provides a new accurate in vivo model for studying molecular mechanisms of luteolysis. 相似文献
64.
Dosage compensation equalizes X-linked gene expression between the sexes. This process is achieved in Caenorhabditis elegans by hermaphrodite-specific, dosage compensation complex (DCC)-mediated, 2-fold X chromosome downregulation. How the DCC downregulates gene expression is not known. By analyzing the distribution of histone modifications in nuclei using quantitative fluorescence microscopy, we found that H4K16 acetylation (H4K16ac) is underrepresented and H4K20 monomethylation (H4K20me1) is enriched on hermaphrodite X chromosomes in a DCC-dependent manner. Depletion of H4K16ac also requires the conserved histone deacetylase SIR-2.1, while enrichment of H4K20me1 requires the activities of the histone methyltransferases SET-1 and SET-4. Our data suggest that the mechanism of dosage compensation in C. elegans involves redistribution of chromatin-modifying activities, leading to a depletion of H4K16ac and an enrichment of H4K20me1 on the X chromosomes. These results support conserved roles for histone H4 chromatin modification in worm dosage compensation analogous to those seen in flies, using similar elements and opposing strategies to achieve differential 2-fold changes in X-linked gene expression. 相似文献
65.
66.
It is generally observed that countries with heavy infectious burden show lower cancer incidence as compared to more affluent nations. With the emerging paradigm on microbial heat shock proteins (hsps) as molecular link between infections and autoimmune diseases, we posit a new hypothesis, the "mimotope-hormesis", on the immunologic impact of infections on regional cancer prevention. According to this, assaults of infection during early adulthood could fortify the immune system to evoke more potent defenses against late-onset diseases, such as cancer, via autoimmunity. Interestingly, both experimental and clinical data support the beneficial role of autoimmunity in long-term cancer survivors. We illustrate this by a comprehensive in silico mimotope (epitope mimicry) analysis of human infectious pathogens against mortalin (mthsp70/PB74/GRP75), a type of hsp70 protein involved in control of cell proliferation, immortalization and tumorigenesis. 相似文献
67.
The Syrian hamster embryo (SHE) cell transformation assay evaluates the potential of chemicals to induce morphological transformation in karyotypically normal primary cells. Induction of transformation has been shown to correlate well with the carcinogenicity of many compounds in the rodent bioassay. Historically the assay has not received wide-spread use due to technical difficulty. An improved protocol for a low pH 6.7 assay was developed by LeBoeuf et al. [R.A. LeBoeuf, G.A. Kerckaert, M.J. Aardema, D.P. Gibson, R. Brauninger, R.J. Isfort, Mutat. Res., 356 (1996) 85-127], that greatly reduced many of the technical difficulties associated with the SHE assay. The purpose of this paper is to describe the most current execution of the pH 6.70 protocol including protocol refinements made since the publication of a comprehensive protocol for this assay in Kerckaert et al. [G.A. Kerckaert, R.J. Isfort, G.J. Carr, M.J. Aardema, Mutat. Res., 356 (1996) 65-84]. 相似文献
68.
Active and passive vaccination against hantavirus pulmonary syndrome with Andes virus M genome segment-based DNA vaccine 总被引:8,自引:0,他引:8
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Hantavirus pulmonary syndrome (HPS) is a rapidly progressing human disease with one of the highest case fatality rates (30 to 50%) of any acute viral disease known. There are no vaccines, effective antiviral drugs, or immunologics to prevent or treat HPS. In an attempt to develop HPS medical countermeasures, we constructed an expression plasmid, pWRG/AND-M, that contains the full-length M genome segment of Andes virus (ANDV), a South American hantavirus. Transfection experiments in cell culture indicated that both the G1 and G2 glycoproteins are expressed from pWRG/AND-M. Rhesus macaques vaccinated by gene gun with pWRG/AND-M developed remarkably high levels of neutralizing antibodies that not only neutralized ANDV but also cross-neutralized other HPS-associated hantaviruses, including Sin Nombre virus. To determine if the antibodies elicited in the monkeys could confer protection, we performed a series of passive-transfer experiments using a recently described lethal HPS animal model (i.e., adult Syrian hamsters develop HPS and die within 10 to 15 days after challenge with ANDV). When injected into hamsters 1 day before challenge, sera from the vaccinated monkeys either provided sterile protection or delayed the onset of HPS and death. When injected on day 4 or 5 after challenge, the monkey sera protected 100% of the hamsters from lethal disease. These data provide a proof of concept for a gene-based HPS vaccine and also demonstrate the potential value of a postexposure immunoprophylactic to treat individuals after exposure, or potential exposure, to these highly lethal hantaviruses. 相似文献
69.
Venegas J. G.; Custer J.; Kamm R. D.; Hales C. A. 《Journal of applied physiology》1985,59(5):1539-1547
Alveolar ventilation during high-frequency ventilation (HFV) was estimated from the washout of the positron-emitting isotope (nitrogen-13-labeled N2) from the lungs of anesthetized paralyzed supine dogs by use of a positron camera. HFV was delivered at a mean lung volume (VL) equal to the resting functional residual capacity with a ventilator that generated tidal volumes (VT) between 30 and 120 ml, independent of the animal's lung impedance, at frequencies (f) from 2 to 25 Hz, with constant inspiratory and expiratory flows and an inspiration-to-expiration time ratio of unity. Specific ventilation (SPV), which is equivalent to ventilation per unit of compartment volume, was found to follow closely the relation: SPV = 1.9(VT/VL)2.1 X f. From this relation and from arterial PCO2 measurements we found an expression for the normocapnic settings of VT and f, given VL and body weight (W). We found that the VL was an important normalizing parameter in the sense that VT/VL yielded a better correlation (r = 0.91) with SPV/f than VT/W (r = 0.62) or VT alone (r = 0.8). 相似文献
70.
IV Zlatkin M Schneider FJ de Bruijn LJ Forney PhD 《Journal of industrial microbiology & biotechnology》1996,17(3-4):219-227
Culturable bacteria from the deep subsurface (179 m) at Cerro Negro, New Mexico were isolated and characterized. The average number of viable aerobic bacteria was estimated to be 5×105g–1 of sediment, but only about 0.1% of these could be recovered on agar medium when incubated under aerobic conditions. Of 158 strains isolated from this depth, 92 were characterized by cellular fatty acid profiles (FAME), 36 by analysis of partial 16S rDNA sequences, and 44 by rep-PCR genome fingerprint analysis using three different sets of oligonucleotide primers (REP, BOX, or ERIC). These analyses showed the majority of isolates (67%) were Gram-positive bacteria and primarily members of genera with a high %G+C DNA. The remaining isolates were -subdivisionProteobacteria (19%) and members of the flavobacteria group (14%). The diversity indices based on these different methods of characterization were very high suggesting this subsurface habitat harbors a highly diverse microbial community. 相似文献