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Biomedical subjects

Q Feng

Publications and source records attributed to Q Feng.

103 records · Page 6Linked to original sources
PubMed1992

[Hormonal regulation of PAI-1 secretion by cultured rat ovarian cells].

Rat ovarian cells produce not only plasminogen activator (tPA) but also plasminogen activator inhibitor type 1 (PAI-1), and their coordinated geneexpression induced by gonadotropins are thought to be responsible for follicular rupture. In this study, it was demonstrated that (1) theca-interstitial compartment synthesizes the majority of PAI-1 activity in the ovary before ovulation, the follicular wall may therefore serve as a specific barrier to prevent the secretion of PA into the extrafollicular compartment; (2) Granulosa cells contribute only small amount of ovarian PAI-1 activity, but synthesize most of tissue-type plasminogen activator activity involved in the process leading to ovulation: (3) Since only matured cumulus-oocyte complexes secrete high level of tPA and PAI-1, both tPA and PAI-1 activity in the conditioned medium may be used as reliable markers for evaluating oocyte quality for in vitro fertilization.

Animals↗
PubMed1991

[Changes of ovarian plasminogen activator and inhibitor during gonadotropin-induced ovulation in rhesus monkeys].

Changes of plasminogen activator (PA) and its inhibitor (PAI-1) activity and antigen have been investigated during PMSG/hCG induced ovulation in rhesus monkeys. It has been demonstrated that the ovarian tissue type PA (tPA) activity, which reaches maximum prior to ovulation and declines thereafter, is closely related to follicular rupture; significant increases in urokinase type PA (uPA) only occurs in granulosa cells after ovulation. Since the secretory activity of ovarian PAI-1 reaches its peak level 12-24 h earlier than tPA the rapid decrease in PAI-1 activity in the approach of ovulation is correlated with the elevation of tPA activity. It is, therefore, suggested that a counterbalance of tPA and PAI-1 activity within the ovary may play an important role in the ovulation mechanism, whereas uPA may be involved in the regulation of corpus luteum formation.

Animals↗
PubMed1991

A comparative study on involvement of tPA activity in ovulation induced by hCG and GnRH agonist in hypophysectomized rats.

A GnRH agonist (5-50 micrograms) is capable of inducing ovulation in PMSG-primed hypophysectomized immature rats, as is the case in hCG-induced ovulation, but 2-4 h earlier than hCG. GnRH-induced ovulation is effectively blocked by the concomitant administration of the GnRH-antagonist which failed to interfere with hCG-induced ovulation, indicating that GnRH and its agonists do not share a receptor with LH/hCG. Like hCG, GnRH is also capable of inducing tissue type (tPA), but not urokinase type (uPA) PA. The plasminogen activator activity in ovarian homogenates and the granulosa and theca-interstitial cells increase in a time-dependent manner, reaching maximum levels just prior to ovulation. Similar to hCG, GnRH also increases tPA activity in cumulus-oocyte complexes in a time-dependent fashion.

Animals↗
PubMed1991

Paradoxical effect of a GnRH agonist on steroidogenesis in cultured monkey granulosa cells.

In this study we demonstrate: (i) The GnRH agonist exerts a direct dose-dependent stimulative effect on the aromatase activity and progesterone production in cultured monkey granulosa cells; (ii) the stimulative effect on steroidogenesis can be completely blocked by concomitant treatment with a GnRH antagonist, suggesting that the actions of GnRH are mediated through stringent stereospecific recognition sites; (iii) in addition to the stimulative effect, the GnRH agonist in the presence of gonadotropins also exerts an inhibitory effect, even though the peptide by itself is more effective in the stimulation of steroidogenesis, and the stimulation of gonadotropin on steroidogenesis could be gradually restored by decreasing the concentration of the GnRH agonist in the culture; and (iv) paradoxical effect can also be observed in the presence of cAMP-inducing agents, suggesting that the inhibitory action of the peptide on gonadotropin-induced steroidogenesis is localized at a step distal to the stringent recognition sites.

Animals↗
PubMed1991

[Role of ventrolateral medullary area in the effect of electrical needling "Neiguan" point on improving acute myocardial ischemia in rabbits].

40 healthy rabbits were anesthetized with 20% urethane and divided into 4 groups in same number: 1) electroacupuncture group physiological saline was applied locally on the S area of the ventral surface of the medulla: 2) naloxone group, naloxone (5 mg/ml. PH 6.5-7) was applied on the S area: 3) propranolol group, propranolol (5 mg/ml. pH 7.0) was applied on the S area: 4) control group, physiological saline was applied on the S area. The state of regional myocardial ischemia of the rabbits was caused by ligating the LAD for 20 minutes. The changes of the blood pressure and the ST values of standard lead II of ECG were observed before ligating and, at 5', 10', 15', 20', 25', 30', 35', 40', 45', 50', 55' and 60' after loosening respectively. Electroacupuncture was applied on "Neiguan" points bilaterally at 10' after ligating for 60 minutes (intensity 6-8 volt, frequency 60/min). The average potential changes of the ST values of standard lead II of 5 times were used as the index to evaluate myocardial ischemia and its recovery course. The followings are the main results of our observation: There were no statistical difference, of blood pressure and the ST values between the four groups before ligation. At 10 minutes after ligation, the ST values were elevated markedly, but there were no statistical significances between the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Points↗
PubMed1990

A method for separating bound versus unbound label during radioiodination.

An inexpensive, highly effective, and safe method for the removal of bound versus unbound label during radiolabeling of proteins is described. The technique employs the use of membrane ultrafiltration technology and returns in one step a highly reproducible product of quality superior to that attained by gel chromatography. Advantages of this technique are a reduction in the quantity of liquid and solid radioactive waste and a significant limitation of potentially harmful manipulation and exposure times.

Chromatography, Gel↗
PubMedDate not supplied

Molecular cloning of a female-specific cDNA with unique repeat sequences from the fat body of the adult locust, Locusta migratoria.

A cDNA clone encoding a 25-kDa protein (25K) was isolated from a cDNA library made from RNA isolated from the adult fat body and ovaries of the locust, Locusta migratoria. The longest open reading frame of this cDNA clone encodes a 225-amino acid polypeptide, the N-terminal end of which was similar to the 21-kDa and 19-kDa juvenile hormone induced proteins identified in the locust hemolymph, but the C-terminal end was different. The C-terminal end of the 25K cDNA contained seven unique repeat elements of 10 amino acids each, most of which are polar residues. Expression of the 25K mRNA was tissue-, development- and sex-specific. A 1.2-kb mRNA was detected using the 25K cDNA as a probe only in the fat body of adult females. The mRNA started to appear at day 4 after the insect molted to the adult and rapidly increased by day 6. The mRNA was absent in the ovarian follicle cells and fat body of adult males. In vitro transcription and translation of the 25K cDNA produced a protein that migrated around 32 kDa on sodium dodecyl sulfate polyacrylamide gels. The 25K cDNA was expressed in a baculovirus expression system and the protein produced also migrated around 32 kDa.

Amino Acid Sequence↗
PubMedDate not supplied

Expression of urokinase, plasminogen activator inhibitors and urokinase receptor in pregnant rhesus monkey uterus during early placentation.

We have investigated plasmin mediated proteolysis associated with trophoblast invasion during early stages of pregnancy in the rhesus monkey. In situ hybridization and immunocytochemical localization were used to define the cellular and tissue distribution of urokinase plasminogen activator (uPA), plasminogen activator inhibitor type 1 (PAI-1) and 2 (PAI-2) and urokinase receptor in early monkey placenta and uterus. Our results indicate: (1) uPA is expressed in proliferating and invasive cytotrophoblast located in chorionic villi as well as in extravillous trophoblast associated with uterine arterioles. This raises the possibility that urokinase may play an important role in trophoblast invasion. (2) PAI-1 mRNA is specifically localized in two areas where invasive trophoblast cells encounter maternal tissue directly. The extravillous cytotrophoblast cells at the maternofetal junction express PAI-1 mRNA. The invasive endovascular trophoblast cells within the uterine arterioles also express PAI-1 mRNA. The location sensitive expression of PAI-1 mRNA at the maternofetal junction may imply a protective function of this protease inhibitor that might be induced through interaction with decidual cells. (3) Urokinase receptor antigen has also been found at the maternofetal junction and in endovascular trophoblast cells of the invaded maternal blood vessel. (4) PAI-2 immunoreactivity is found in association with cytotrophoblast cells in anchoring choronic villi suggesting its association with early placentation. In conclusion, we propose that the plasmin/plasminogen activator system may not only regulate extracellular matrix degradation, but also modify migration and invasive behaviour of extravillous trophoblast cells, during early placentation.

Animals↗
PubMedDate not supplied

Plasminogen activators and inhibitors are transcribed during early macaque implantation.

Plasminogen activators and inhibitors may be important early in primate implantation but evidence for this is sparse in non-human primates. We define the expression of urokinase type plasminogen activator (uPA), tissue-type plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1) and type 2 (PAI-2), the receptor for uPA (uPAR) and fibrin/fibrinogen in monkey implantation sites. In situ hybridization and immuno-histochemical localization of rhesus monkey implantation sites (day 15-16 postovulation) indicate: (1) uPA mRNA is localized to placental trophoblast, epithelial plaque and endometrial stroma. (2) tPA mRNA is mainly expressed in glandular cells of endometrium. (3) PAI-1 expression is linked to a specific population of trophoblasts that confront maternal cells, adding support to our view that it has a regulatory role in trophoblast invasion. (4) Localization of tPA antigen confirms that uterine glands are the major source of tPA and that it is also closely associated with fibrin(ogen) suggesting its possible function during implantation is fibrinolysis. (5) Unlike uPA mRNA, however, the distribution of uPA protein and its cell surface receptor uPAR suggests that it mediates trophoblast invasion and plays a significant role in angiogenesis. (6) PAI-2, the inhibitor associated with pregnancy in humans, was found in unidentified cells located specifically along the maternofetal junction. This localization adjacent to areas of cell death at the maternofetal junction implies that it may have a role as a protective curtain with anti-apoptotic function. In conclusion our results suggest that gene expression of PAs and PAIs in early implantation sites are tissue-specific, location-sensitive and function-related.

Animals↗
PubMedDate not supplied

Hair mercury levels of residents in China, Indonesia, and Japan.

The authors used gold-amalgamation cold-vapor atomic absorption spectrometry and ECD-gas chromatography to analyze total mercury and methylmercury levels in hair samples obtained from 362 residents in Harbin, China; Medan, Indonesia; and Tokushima, Japan. In this study, the authors initially questioned whether mercury levels in hair differed among different study areas, and if there were differences, they questioned the contributing factors. In the three countries surveyed, total mercury and methylmercury levels in hair were lowest in residents of China and were highest in residents of Japan. In the district of Tokushima, Japan, total mercury and methylmercury levels were highest in the coastal district, followed by the middle district; the lowest levels occurred in the mountainous district. In Japan, an individual's total mercury level correlated very closely with that person's methylmercury level; in China and Indonesia, the correlation between these 2 parameters was low. No subjects in China or Indonesia had high levels of methylmercury in hair; this was true even if their total mercury levels were high. This finding suggests that the high total mercury levels observed in some residents of China and Indonesia reflected exposure to inorganic mercury. In Japan, mercury (especially methylmercury) levels in hair samples were quite high. Fish and shellfish, caught in seas uncontaminated by human activity, appeared to be major sources of the high levels of hair mercury in Japanese subjects.

Adult↗