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Biomedical subjects

Q Feng

Publications and source records attributed to Q Feng.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Studies on microbial factor on color change of Dunhuang mural. I. Classification of microbes on color-changed mural and property of some typical species].

Microbial strains were isolated from 51 typical color changed samples of mural in 6 grottos of Dunhuang Mogao Gretto. After identification, it is proved that belong to 6 genera of bacteria and 5 genera of mould. Bacillus, Alcaligenes and Penicillium were dominant species in all of them. In the imitative experiment, it is found that Cladosporium sp., A. niger and two strains of bacteria have a great effect on the color change of red pigment of mural and aging of sizing agent.

Bacteria↗
PubMed1998

[Studies on microbial factor on color change of Dunhuang mural. III. Effect of Cladosporium sp. on color-change of red lead in the surface of mural].

The conditions isolated Cladosporium sp. from Mural of Dunhuang grottoe germinated on the surface of imitated mural were as follows: 20 degrees C RH 60% or 30 degrees C RH 50%, which could be reached occasionally in some grottoes. Bone glue had protective function on red lead, while Cladosporium sp. could decompose bone glue and form some metabolite (such as oxalic acid, etc) as it grows. Then it could form a special chemical circumstance, which promoted the change from red lead to while lead.

Cladosporium↗
PubMed1997

Trace element contents in hair of residents from Harbin (China), Medan (Indonesia), and Tokushima (Japan).

The concentrations of 19 trace element in hair samples from 1273 residents of Harbin (China), Medan (Indonesia), and Tokushima (Japan) were measured by inductively coupled plasma emission spectrometry. The mean concentrations of Ba, Ca, and Se were significantly higher in the Harbin hair samples when compared to those from Medan, but Al, B, Cu, Fe, Mn, Na, Pb, Ti, Zn, and K were significantly higher in Medan than in Harbin hair samples. The differences in the mean concentrations of As, Cr, Mg, P, Sn, and Sr between the Medan and Harbin lots were not significant. In the Tokushima hair samples, Na and K were significantly higher, but As, B, Ba, Ca, Cr, Mg, Mn, Pb, Sn, Sr, and Se were significantly lower than in the Harbin hair samples. The differences in the mean concentrations of Al, Cu, Fe, P, Ti, and Zn between Harbin and Tokushima were not significant. In the Medan hair samples, Al, As, B, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Pb, Sn, Sr, Ti, and Zn were significantly higher, but P and Se were significantly lower than in Tokushima hair samples. Differences in mean concentrations of Na and K between Tokushima and Medan were not significant.

Adult↗
PubMed1997

[Accumulative trends of ephedrine and pesudoephedrine in Ephedra sinica].

In Yi Kezhao Alliance, the content of ephedrine and pseudoephedrine in Ephedra sinica is in a ratio of four to six. The total content of ephedine and pseudoephedrine form cultivated Ephedra sinica is higher than that of wild one, and in direct ratio with the years of plant. For the content enhance of total alkaloids, decreasing irrigation and applying middlingly fertilizer is more effective measure.

Alkaloids↗
PubMed1996

Human L1 retrotransposon encodes a conserved endonuclease required for retrotransposition.

Human L1 elements are highly abundant poly(A) (non-LTR) retrotransposons whose second open reading frame (ORF2) encodes a reverse transcriptase (RT). We have identified an endonuclease (EN) domain at the L1 ORF2 N-terminus that is highly conserved among poly(A) retrotransposons and resembles the apurinic/apyrimidinic (AP) endonucleases. Purified L1 EN protein (L1 ENp) makes 5'-PO4, 3'-OH nicks in supercoiled plasmids, shows no preference for AP sites, and preferentially cleaves sequences resembling L1 in vivo target sequences. Mutations in conserved amino acid residues of L1 EN abolish its nicking activity and eliminate L1 retrotransposition. We propose that L1 EN cleaves the target site for L1 insertion and primes reverse transcription.

Amino Acid Sequence↗
PubMed1996

Hill et al. Reply.

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Journal Article↗
PubMed1996

[The effects of propylthiouracil on the fetal thyroid and serum concentration in pregnant women].

In order to study the effects of propylthiouracil (PTU) on the fetal thyroid and serum concentration, 9 women undergoing therapeutic abortion at the second trimester of pregnancy were given a single dose of 50, 100 and 150 mg PTU respectively. The concentrations of PTU in the maternal and fetal serum and those in the fetal thyroid tissues were determined with a high-performance liquid chromatographic method, the lowest limit of which was 25 micrograms/L. After an oral bolus of PTU, the PTU concentrations in the maternal serum reached a peak level after one hour and there was a wide individual variation of the peak value. The study showed PTU could be transferred through the placenta from the maternal blood to the fetal blood and highly accumulated in the fetal thyroid tissues. The fetal serum PTU concentrations correlated with those of their mothers at the same time (r = 0.7084, P < 0.02) and the concentrations in the fetal thyroid tissues could be evaluated by the maternal serum peak level after an oral bolus. PTU didn't inhibit the fetal thyroid peroxidase activity even when the maternal serum PTU concentration reached 4 mg/L, which is the lowest effective therapeutic concentration of PTU in adults.

Adult↗
PubMed1996

[Effects of saponins from stems and leaves of Panax quinquefolium L. on the contraction of rabbit aortic strips].

It has been found out that the saponins from stems and leaves of Panax quinquefolium (PQS) can non-competitively antagonize the dose-response curves of norepinephrine (NE), potassium chloride and calcium chloride on the isolated aortic strips of rabbits, and obviously inhibit intracellular and extracellular Ca2(+)-dependent contraction of the aortic strips induced by NE. These effects of PQS are similar to verapamil.

Animals↗
PubMed1995

Studies on the role of plasminogen activators and plasminogen activator inhibitor type-1 in rat corpus luteum of pregnancy.

Luteal development and demise are characterized by substantial tissue destruction and remodeling, which is associated with local production of plasminogen activation. Recently we reported involvement of tissue-type plasminogen activator (tPA) in luteolysis in rhesus monkeys. In this study, we further investigated changes in expression of both tPA and urokinase-type plasminogen activator (uPA) activity during various developmental stages of rat corpus luteum (CL) of pregnancy and their possible physiological roles in luteolysis. Rat CL or dispersed luteal cells in vitro are capable of producing both tPA and uPA, and a plasminogen activator inhibitor type-1, in a stage-dependent manner. However, only tPA activity significantly increases in late phases of CL development. Furthermore, the increase in tPA activity in the CL is well correlated with a sharp decrease in luteal progesterone production. Addition of exogenous tPA to the luteal culture considerably decreases progesterone production. In contrast, immunoneutralization of endogenously produced tPA activity by inclusion of tPA monoclonal antibody in the culture results in a significant increase in luteal progesterone production. It is therefore suggested that tPA may also be involved in suppression of rat luteal function. This hypothesis is further supported by the findings that interferon-gamma significantly inhibits luteal basal and hCG-stimulated progesterone production and also stimulates basal and hCG-induced tPA activity. On the basis of the data provided in this study and similar findings in monkeys, we conclude that endogenously produced tPA in late phase of CL development may regulate luteal regression through local autocrine or paracrine action.

Animals↗
PubMed1995

[A new subspecies of Streptomyces griseoflavus].

In the process of research of microorganism ecology on Dun Huang freseo a strain of Streptomyces culture No. 25706 was isolated. Its morphological cultural characteristics and physiological properties as well as antimicrobial spectrum were studied. It is near to Streptomyces griseoflavus as described in the literature, but there are some significant differences between the two strains. Therefore, it was considered, to be a new subspecies and named Streptomyces griseoflavus subsp. dunhuangensis n. subsp.

China↗
PubMed1995

Changes of plasma endothelin and atrial natriuretic peptide during the onset and after termination of paroxysmal supraventricular tachycardia.

Radioimmunoassays were used to measure the concentration changes of plasma endothelin (ET) and atrial natriuretic peptide (ANP) during the onset and after termination of paroxysmal supraventricular tachycardia (SVT). 30 cases were reviewed and comparisons with 42 normal subjects were made. There are very significant differences (P < 0.0001) in the concentration changes of both plasma ET and ANP during the onset and 30 minutes after the termination of SVT. During the onset period of SVT, the plasma ET and ANP were markedly elevated and 30 minutes after its termination they were lowered significantly, but their concentrations were still 2-fold higher than those of the control group. As the biological effects of ANP and ET are antagonistic to each other, their parallel elevation and lowering of plasma concentrations during and after the termination of SVT reveal that these 2 hormones participate in the pathophysiological process of SVT. This phenomenon is possibly one of the homeostatic regulatory functions in the organism.

Adult↗