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31.
F. Kohi D.K. Agrawal J.B. Cheng A.K. Bewtra R.G. Townley 《Prostaglandins & other lipid mediators》1987,33(1)
A simple and sensitive radioreceptor assay (RRA) for leukotrienes (LTs) was developed using a highly specific [3H]leukotriene D4 (LTD4) binding to guinea pig lung membrane homogenates. The assay can detect down to 0.15 pmol of LTD4. The values for fifty percent inhibition of bound [3H]LTD4 was 1.5 nM for LTD4, 45 nM for LTC4 and 24 nm for LTE4. LTB4 at 3.0 × 10−5 M had no effect on [3H]LTD4 binding. The RRA for LTs in the absence of serine-borate complex was bi-specific for both LTC4 and LTD4. However, in the presence of 20 nM serine-borate this method was highly specific for LTD4. Recovery rate averaged 87.2% after ethanol extraction and evaporation of known amounts of LTD4. When the radioreceptor assay and radioimmunoassay data for leukotriene levels in the samples were compared to each other, an excellent correlation was observed with a correlation coefficient ‘r’ of 0.992. The assay was also validated by quantitation of LTs released from human granulocytes stimulated with calcium ionophore, A23187. The method is simpler, less expensive, and more specific for LTD4 than the other methods such as high pressure liquid chromatography and radioimmunoassay and is suitable for routine measurement of either LTD4 specifically or LTC4 plus LTD4 simultaneously in one cell system. 相似文献
32.
We have measured by radioimmunoassay the production of leukotrienes (LTC4 and LTB4) and prostaglandins (PGE2 and PGF2 alpha) in the rat uterus on Days 1 through 6 of pregnancy. The production is defined as the synthesis minus the degradation for a defined period. The production of LTC4 or LTB4 remained unaltered on days 1-3, but exhibited a marked increase on Day 4 showing a peak at noon. This was then followed by a sharp decline on Day-5 morning. A small but consistent peak in uterine LT production was also noticed on Day-5 noon prior to implantation and this was followed by a decline on Day-6 morning i.e. after initiation of implantation. The production profile of PGE2 and PGF2 alpha showed a striking resemblance to that of LTs; one exception being that maximal PG production was noticed on Day-4 morning and preceded the peak production of LTs. These vasoactive arachidonate derivatives reached their peak production rates at around the time when a surge in estrogen level is noticed in the uterus on Day 4. Implantation is a local proinflammatory type of reaction that is associated with increased uterine vascular permeability. Vascular changes in inflammatory reactions are provoked by two kinds of chemical mediators: vasodilators and agents that increase vascular permeability. PGs (especially of the E series) are known as vasodilators, while LTs and histamine mediate increases in vascular permeability. Therefore, an interaction between LTs, PGs, and histamine could be important for uterine preparation for implantation and/or implantation per se. 相似文献
33.
Purification and comparison of the structures of human liver acidic alpha-D-mannosidases A and B. 总被引:2,自引:1,他引:1 下载免费PDF全文
Human liver alpha-D-mannosidases A and B were purified 11 500-fold and 2000-fold respectively. Both showed microheterogeneity when analysed by isoelectric focusing. Alpha-D-Mannosidases A and B are immunologically identical but differ in their range of pI values, molecular masses, uptake into fibroblasts and subunit compositions. Alpha-D-Mannosidase A consists of equimolar proportions of subunits of molecular masses 62 kDa and 26 kDa, which are linked by disulphide bridges in the intact enzyme. Alpha-D-Mannosidase B also contains a small subunit, of molecular mass 26 kDa, and a variable mixture of larger subunits, of molecular masses 58 kDa and 62 kDa. The 62 kDa and 58 kDa subunits, but not the 26 kDa one, contain concanavalin A-recognizing glycans. The 58 kDa subunit has a lower pI, contains less high-mannose glycans but probably contains more mannose 6-phosphate than the 62 kDa subunit. It is postulated that the differences in structure and properties of alpha-D-mannosidases A and B are due to differences in the state of processing of the large subunit. This suggestion is consistent with a single locus on chromosome 19 for lysosomal alpha-D-mannosidase. 相似文献
34.
本文根据沉积物成因、古气候和古生物特征,把禄丰古猿化石产地新第三纪地层划分为晚中新世石灰坝组和早上新世庙山坡组。据岩性和岩相特征,可划分出五个不同的沉积阶段,每个阶段代表不同的沉积环境。古猿和其他脊椎动物化石主要埋在石灰坝组(四段)湖泊沼泽化沉积环境,次之为庙山坡组(五段)河流相沉积环境。 相似文献
35.
Metabolism of 9-(1,3-dihydroxy-2-propoxymethyl)guanine, a new anti-herpes virus compound, in herpes simplex virus-infected cells 总被引:18,自引:0,他引:18
Y C Cheng S P Grill G E Dutschman K Nakayama K F Bastow 《The Journal of biological chemistry》1983,258(20):12460-12464
The metabolism of 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), one of the most promising new anti-herpes virus compounds, in HeLa cells infected with herpes simplex virus type 1 was compared with that in the uninfected HeLa cells. In the virus-infected cells, the uptake of DHPG was enhanced and the major metabolites were found to be the mono-, di-, and triphosphate derivatives. The formation of these metabolites was dependent on the extracellular concentration of DHPG (0.5 to 5.0 microM). Virus-induced thymidine kinase was capable of phosphorylating DHPG to its monophosphate which could be further phosphorylated to the di- and triphosphate derivatives by the host cellular enzymes. Incorporation of the DHPG into DNA was observed in virus-infected cells. In contrast with 9-(2-hydroxyethoxymethyl)guanine, DHPG seemed not to serve as a chain terminator, but to be incorporated internally into DNA strands. 相似文献
36.
J Kruuv D Glofcheski K H Cheng S D Campbell H M Al-Qysi W T Nolan J R Lepock 《Journal of cellular physiology》1983,115(2):179-185
The Arrhenius plot of the rate of V79 Chinese hamster cell inactivation due to hypothermia has a "break" around 7-10 degrees C with optimum storage temperature for unprotected cells being about 10 degrees C. Addition of the membrane lipid perturber, butylated hydroxytoluene, improves survival of cells when compared to controls at temperatures below this break but not above. Arrhenius plots of growth rates of the cells show breaks at 30 and 40 degrees C. Measurements of membrane fluidity by electron spin resonance or membrane polarization anisotropy by fluorescence spectrophotometry techniques as a function of temperature in these cells also reveal "breaks" centered around 8 and 30 degrees C. Hence, the changes in the rate of cell inactivation and growth as a function of temperature may be related to membrane lipid phase changes. 相似文献
37.
The recovery of indicator bacteria on selective media 总被引:15,自引:0,他引:15
38.
Himasthla quissetensis: uptake and utilization of glucose by rediae as determined by autoradiography and respirometry 总被引:1,自引:0,他引:1
Daughter rediae of Himasthla quissetensis removed from the digestive gland of Nassarius obsoletus were placed in sterilized seawater fortified with antibiotics. When [3H]-glucose was added to this medium and autoradiographs were made after 3, 9, and 24 hr of exposure, labeling was observed associated with the redial walls and developing germ balls and cercariae within the brood chambers. Respirometric determinations on starved rediae suspended in the seawater medium with and without glucose revealed the rate of oxygen utilization by rediae exposed to exogenous glucose is significantly elevated. These results are interpreted to mean that the daughter rediae of H. quissetensis can take up and utilize glucose. 相似文献
39.
40.