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排序方式: 共有1331条查询结果,搜索用时 15 毫秒
981.
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983.
Wouter Willaert Marie De Vos Tom Van Hoof Louke Delrue Piet Pattyn Katharina D’Herde 《PloS one》2015,10(3)
The quality of tissue preservation in Thiel embalmed bodies
varies. Research on the administered embalming volume and its vascular distribution may elucidate one of the mechanisms of tissue preservation and allow for new applications of Thiel embalming. Vascular embalming with (group 1, n = 15) or without (group 2, n = 20) contrast agent was initiated in pig kidneys. The distribution of Thiel embalming solution in group 1 was visualized using computed tomography. The kidneys in both groups were then immersed in concentrated salt solutions to reduce their weight and volume. Afterwards, to mimic a lifelike circulation in the vessels, group 2 underwent pump-driven reperfusion for 120 minutes with either paraffinum perliquidum or diluted polyethylene glycol. The circulation was imaged with computed tomography. All of the kidneys were adequately preserved. The embalming solution spread diffusely in the kidney, but fluid accumulation was present. Subsequent immersion in concentrated salt solutions reduced weight (P < 0.01) and volume (P < 0.01). Reperfusion for 120 minutes was established in group 2. Paraffinum perliquidum filled both major vessels and renal tissue, whereas diluted polyethylene glycol spread widely in the kidney. There were no increases in weight (P = 0.26) and volume (P = 0.79); and pressure further decreased (P = 0.032) after more than 60 minutes of reperfusion with paraffinum perliquidum, whereas there were increases in weight (P = 0.005), volume (P = 0.032) and pressure (P < 0.0001) after reperfusion with diluted polyethylene glycol. Arterial embalming of kidneys results in successful preservation due to complete parenchymatous spreading. More research is needed to determine whether other factors affect embalming quality. Dehydration is an effective method to regain the organs’ initial status. Prolonged vascular reperfusion with paraffinum perliquidum can be established in this model without increases in weight, volume and pressure. 相似文献
984.
Host density can increase infection rates and reduce host fitness as increasing population density enhances the risk of becoming infected either through increased encounter rate or because host condition may decline. Conceivably, potential hosts could take high host density as a cue to up-regulate their defence systems. However, as host density usually covaries with food availability, it is difficult to examine the importance of host density in isolation. Thus, we performed two full-factorial experiments that varied juvenile densities of Daphnia magna (a freshwater crustacean) and food availability independently. We also included a simulated high-density treatment, where juvenile experimental animals were kept in filtered media that previously maintained Daphnia at high-density. Upon reaching adulthood, we exposed the Daphnia to their sterilizing bacterial parasite, Pasteuria ramosa, and examined how the juvenile treatments influenced the likelihood and severity of infection (Experiment I) and host immune investment (Experiment II). Neither juvenile density nor food treatments affected the likelihood of infection; however, well-fed hosts that were well-fed as juveniles produced more offspring prior to sterilization than their less well-fed counterparts. By contrast, parasite growth was independent of host juvenile resources or host density. Parasite-exposed hosts had a greater number of circulating haemocytes than controls (i.e., there was a cellular immune response), but the magnitude of immune response was not mediated by food availability or host density. These results suggest that density dependent effects on disease arise primarily through correlated changes in food availability: low food could limit parasitism and potentially curtail epidemics by reducing both the host’s and parasite’s reproduction as both depend on the same food. 相似文献
985.
Wouter H. Lamers Marian van Roon Piet G. Mooren André De Graaf Robert Charles 《In vitro cellular & developmental biology. Plant》1985,21(11):606-611
Summary A completely defined medium (EHM-1), which reflects the amino acid composition of fetal rat serum and contains albumin as
the sole proteinaceous compound, allows the accumulation of carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase
in the presence of dexamethasone, dibutyryl cyclic AMP, and triiodothyronine to approximately twice the level attained in
a standard culture medium (RPMI 1640) supplemented with 10% fetal bovine serum (and hormones). Using the EHM-1 medium we could
show that the capacity of hepatocytes to synthesize phosphoenolpyruvate carboxykinase in the presence of hormones is manifest
as soon as the cells differentiate from the embryonic foregut (embryonic Day 11). Furthermore we could show that embryonic
hepatocytes can become binuclear or polyploid when cultured in the presence of thyroid hormone.
These investigations were supported in part by the Dutch Foundation for Medical Research FUNGO (grant 13-50-38). 相似文献
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988.
Arthur Van Aerschot Piet Herdewijn Hubert Vanderhaeghe 《Nucleosides, nucleotides & nucleic acids》2013,32(1):75-90
Abstract The phosphotriester method for synthesis of oligonucleotides has been used for evaluating silica with spacer groups. Three different spacers were synthesized of which a long chain alkylamine, a double glycine and a double y-aminobutyric acid unit. Only the double glycine spacer improved the yields of the first condensations and is now routinely used in our laboratory. 相似文献
989.
Robert S. Jansen Sunny Mahakena Marcel de Haas Piet Borst Koen van de Wetering 《The Journal of biological chemistry》2015,290(51):30429-30440
The ubiquitous efflux transporter ABCC5 (ATP-binding cassette subfamily C member 5) is present at high levels in the blood-brain barrier, neurons, and glia, but its in vivo substrates and function are not known. Using untargeted metabolomic screens, we show that Abcc5−/− mice accumulate endogenous glutamate conjugates in several tissues, but brain in particular. The abundant neurotransmitter N-acetylaspartylglutamate was 2.4-fold higher in Abcc5−/− brain. The metabolites that accumulated in Abcc5−/− tissues were depleted in cultured cells that overexpressed human ABCC5. In a vesicular membrane transport assay, ABCC5 also transported exogenous glutamate analogs, like the classic excitotoxic neurotoxins kainic acid, domoic acid, and NMDA; the therapeutic glutamate analog ZJ43; and, as previously shown, the anti-cancer drug methotrexate. Glutamate conjugates and analogs are of physiological relevance because they can affect the function of glutamate, the principal excitatory neurotransmitter in the brain. After CO2 asphyxiation, several immediate early genes were expressed at lower levels in Abcc5−/− brains than in wild type brains, suggesting altered glutamate signaling. Our results show that ABCC5 is a general glutamate conjugate and analog transporter that affects the disposition of endogenous metabolites, toxins, and drugs. 相似文献
990.