Biomedical subjects

L J Wang

Publications and source records attributed to L J Wang.

At least 73 records · Page 4Linked to original sources

PubMed1996

Regulation of the renal Na-HCO3 cotransporter: VI. Mechanism of the stimulatory effect of protein kinase C.

We have previously shown that the activity of the Na-HCO3 cotransporter is stimulated by protein kinase C (PKC) activation, but the mechanism responsible for this effect is not clear. We have shown that cultured proximal tubule cells of the rabbit have DIDS-sensitive Na-HCO3 cotransporter activity as assessed by HCO3-dependent 22Na uptake or by measurement of intracellular pH. In cells loaded with BCECF and treated with the amiloride analogue, ethylisopropyl amiloride, removal of extracellular Na was associated with a rapid decrease in pH which returned to normal with re-addition of Na. This pH recovery was inhibited by DIDS and was used to quantify the activity of the Na-HCO3 cotransporter. In the present study, we utilized primary cultures of the proximal tubule of the rabbit to examine the effect of PKC activation on the activity of the Na-HCO3 cotransporter. Short term incubation (5 min) with the active phorbol ester, phorbol 12-myristate, 13-acetate (PMA), 10(-7) M, caused a significant stimulation of the Na-HCO3 cotransporter activity as compared to controls. Incubation for two hours also caused a significant stimulation of the Na-HCO3 cotransporter activity. The inactive analogue of PMA, 4-alpha phorbol, failed to alter the cotransporter. Similar results were observed when we examined the effect of PMA on HCO3-dependent 22Na uptake. The effect of PMA to stimulate the cotransporter was mediated by PKC activation since it could be prevented by the PKC inhibitors, calphostin C or sphingosine, or by prior PKC depletion. The long term but not the short term effect of PMA to stimulate the Na-HCO3 cotransporter activity was prevented by the protein synthesis inhibitors, actinomycin D or cycloheximide. The early effect of PKC to stimulate the cotransporter appeared to be associated with increased phosphorylation of a 56 kD protein band, while the late effect appeared to be associated with an increase in immunoreactive content of a 56 kD protein which is thought to be an active component of the cotransporter. Thus PKC stimulation activates the Na-HCO3 cotransporter by two distinct mechanisms: a long term effect which is protein synthesis-dependent and a short term effect which is protein synthesis-independent and is likely mediated by phosphorylation.

Animals↗

PubMed1996

Inhibitory effect of tetrahydropalmatine on calcium current in isolated cardiomyocyte of guinea pig.

AIM: To study the effect of tetrahydropalmatine (THP) on calcium channels in ventricular single cells of guinea pig heart. METHODS: Patch-clamp technique (whole cell recording) was used to observe calcium current in ventricular myocytes. RESULTS: THP decreased ICa in ventricular myocytes with a dose and frequency-dependent manner. THP (0.1, 1, and 10 mumol.L-1) decreased ICa from 1.15 +/- 0.22, 0.91 +/- 0.18, and 1.60 +/- 0.42 nA (control) to 0.9 +/- 0.21 (P < 0.01), 0.56 +/- 0.21 (P < 0.01), and 0.83 +/- 0.21 nA (P < 0.05), respectively, number of cells is five in each group (n = 5), and the rates of the depression of ICa were 22%, 38%, and 48%, respectively. The effect was easily reduced by washing the cell with the Tyrode's solution. The current-voltage relation curve showed that the potential producing peak value of ICa was 0 mV at which THP had the most markedly inhibited action on ICa. When the stimulating frequency was changed, ICa varied in a frequency-dependent manner 5 min after THP was given, and the inhibition of THP was stronger at 2 Hz than that at 0.1 Hz. CONCLUSION: THP possessed a Ca2+ channel blocking effect.

Action Potentials↗

PubMed1995

Optimal polymerase chain reaction amplification for preimplantation diagnosis in cystic fibrosis (delta F508)

OBJECTIVE: To evaluate direct polymerase chain reaction amplification of mutation on single embryo cells for the routine preimplantation diagnosis of cystic fibrosis. DESIGN: Direct polymerase chain reaction amplification of mutation was performed to identify the cystic fibrosis delta F508 mutation in human blood DNA, single lymphocytes, embryos, and embryo cells obtained by biopsy. Preimplantation diagnosis was performed for a couple who were heterozygous carriers of the delta F508 mutation. SETTING: Laboratory for preimplantation diagnosis in a reproductive medicine unit. MAIN OUTCOME MEASURE: Correct diagnosis of homozygous normal, heterozygous, and homozygous abnormal DNA of the cystic fibrosis delta F508 mutation. RESULTS: 45 blood samples (18 homozygous normal, 17 heterozygous, and 10 homozygous abnormal) and 204 single lymphocytes from known sources showed 100% amplification and were diagnosed correctly. 17 human embryos and 52 normal nucleated embryo cells obtained by single cell embryo biopsy also showed 100% amplification. After a miscarriage of the initial pregnancy (diagnosed at preimplantation to be homozygous normal) in the heterozygous carrier couple, fetal tissue was confirmed to be homozygous normal. CONCLUSION: Direct polymerase chain reaction amplification of mutation is a simple, fast, reliable test for the common cystic fibrosis mutation (delta F508) in blood DNA and single cells and should be applicable to routine programmes of general screening, maternal blood examination, and preimplantation diagnosis.

Base Sequence↗

PubMed1995

Regulation of renal Na-HCO3 cotransporter: III. Presence and modulation by glucocorticoids in primary cultures of the proximal tubule.

We looked for the presence of the Na-HCO3 cotransporter in primary cultures of the proximal tubule and examined the modulation of this cotransporter by glucocorticoid hormones. Primary cultures of the proximal tubule of the rabbit have Cl-independent, HCO3-dependent 22Na uptake which is DIDS-sensitive. In addition, in cells loaded with BCECF and perfused with Cl-free solution, removal of Na was associated with a decrease in intracellular pH which returned to normal with re-addition of Na. The pH recovery was not inhibited by EIPA but was sensitive to DIDS. These findings are compatible with existence of Na-HCO3 cotransporter in these cells. We examined the role of glucocorticoids on the activity of the Na-HCO3 cotransporter by culturing proximal tubule cells in the presence of hydrocortisone and when confluence was reached, hydrocortisone was deleted from the medium. In the absence of hydrocortisone, the activity of the cotransporter, measured either isotopically or fluorometrically, was significantly decreased, whereas re-addition of hydrocortisone 10(-8) M, restored the activity of the cotransporter to normal levels. The effect of hydrocortisone could not be duplicated by aldosterone, suggesting a glucocorticoid-dependent effect. Dexamethasone, a glucocorticoid without mineralocorticoid activity, stimulated the activity of the cotransporter within physiologic concentrations and this effect was blocked by progesterone. The effect of dexamethasone was time-dependent and was prevented by cycloheximide, a protein synthesis inhibitor. These results demonstrate that primary cultures of the proximal tubule have Na-HCO3 cotransporter activity which is modulated by physiological concentrations of glucocorticoids through a protein synthesis-dependent mechanism.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1995

Cellular composition of primary cultures of human granulosa-lutein cells and the effect of cytokines on cell proliferation.

The cellular composition of cells collected from the follicular fluid obtained during the IVF procedure and cultured in vitro was examined, as well as the effects of two cytokines, interleukin-2 (IL-2) and tumour necrosis factor-alpha (TNF alpha), on the proliferation of individual cell types. After 48 h in culture, most of the cells were granulosa-lutein cells exhibiting positive staining against 3-beta-hydroxysteroid dehydrogenase (3 beta-HSD). About one-third of the total cell population stained positive with monoclonal antibodies against specific antigen sites on lymphohaemopoietic cells, including B-lymphocytes, T-lymphocytes, natural killer cells, monocytes and macrophages. During this 48-h period, IL-2 and TNF alpha significantly (P < 0.05) increased the proportion of leukocyte common antigen (LCA)-positive cells and monocytes. At the end of 144 h in culture, although LCA-positive cells and monocytes were still present, there were fewer. The main targets for the proliferative effects of IL-2 and TNF alpha in this culture system during the first 48 h are leukocytes rather than steroid-producing cells. Thus, any observed effects from the addition of cytokines in this system may be due to indirect effects of cytokine-activated leukocytes on granulosa-lutein cells.

Cell Division↗

PubMed1995

Effects of tumour necrosis factor alpha (TNF alpha) on ovulation in the rat ovary.

The effects of tumour necrosis factor alpha (TNF alpha) on ovulation rate, ovarian secretion of steroids, and on tissue concentrations of the ovulatory mediators plasminogen activator (PA) and prostaglandins were examined in rat ovaries perfused in vitro for 20 h. Unstimulated control ovaries did not ovulate whereas luteinizing hormone (LH; 100 ng mL-1) induced ovulations in all ovaries (2.6 +/- 0.7). TNF alpha (40 ng mL-1) induced ovulations in 3 of 5 ovaries (0.8 +/- 0.4). When TNF alpha was added concomitantly with LH, the LH-induced ovulation rate was increased four-fold (10.6 +/- 1.3). This effect was not seen when TNF alpha was added 5 h after LH (3.2 +/- 0.6). More progesterone was released when TNF alpha was combined with LH by comparison with LH alone. Tissue concentrations of prostaglandin F2 alpha (PGF2 alpha) and PGE were increased by the addition of TNF alpha when compared with the control group, but did not exceed those observed in the LH group, when TNF alpha was combined with LH. PA activity in the tissue was unaffected by TNF alpha and the LH-induced increase in PA activity was inhibited when TNF alpha was combined with LH. The results demonstrate that the proinflammatory cytokine TNF alpha promotes ovulations in the rat ovary.

Animals↗

PubMed1995

Altered p53 in microdissected, metachronous, premalignant and malignant oral lesions from the same patients.

Aims-To determine whether mutant p53 alleles harboured by malignant tumours of the oral cavity were also present in previous premalignant lesions at the same site.Methods-Paraffin embedded tumour specimens along with their premalignant counterparts were analysed for p53 alterations using immunohistochemistry, microdissection, polymerase chain reaction amplification, and DNA sequencing.Results-Malignant lesions from five of eight patients showed overexpression of p53 protein by immunohistochemistry. Upon DNA sequencing, two of these five specimens had p53 mutations. Of the five patients whose cancers showed p53 overexpression by immunohistochemistry, three had previous premalignant lesions that also had immunohistochemically detectable p53 protein. However, DNA sequencing showed that none of these three had mutations in the p53 gene. The remaining five premalignant lesions had no immunohistochemically detectable p53 protein.Conclusions-Some premalignant lesions have increased p53 protein which can be detected by staining with antibody to p53. This staining is not caused by mutations in p53 that are found in subsequent tumours at the same site.

Journal Article↗

PubMed1995

Regulation of renal cortical Na-HCO3 cotransporter. II. Role of G proteins.

We examined the regulation of the renal cortical basolateral Na-HCO3 cotransporter by G proteins. Na-HCO3 cotransporter activity was measured in highly purified rabbit renal cortical basolateral membranes (BLMV) as the difference in 22Na uptake in presence of HCO3- and gluconate. HCO(3-)-dependent 22Na uptake was significantly inhibited by 10 microM guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), a G protein activator. In contrast, addition of 50 microM guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), an inhibitor of G protein, prevented the inhibition of the Na-HCO3 cotransporter activity by GTP gamma S. AlF4-, another G protein activator, also inhibited the activity of the Na-HCO3 cotransporter. This inhibitory effect of G protein on the Na-HCO3 cotransporter activity was not prevented by dideoxyadenosine, an adenylate cyclase inhibitor, or by the protein kinase A inhibitor, suggesting a direct effect of G protein on the cotransporter. To identify the G proteins that mediate the regulation of the Na-HCO3 cotransporter, purified BLMV were ADP ribosylated in presence of cholera toxin or pertussis toxin. Autoradiograms of BLMV incubated with [32P]NAD showed that cholera and pertussis toxins caused ADP ribosylation of 42- and 41-kDa G proteins, respectively. To determine whether the ADP ribosylation by cholera or pertussis toxin was associated with alterations of the Na-HCO3 cotransporter activity, we measured HCO(3-)-dependent 22Na uptake in BLMV treated with 20 micrograms/ml cholera toxin or with 100 ng/ml pertussis toxin. Na-HCO3 cotransporter activity was significantly decreased by both cholera and pertussis toxins.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate Ribose↗

PubMed1995

Regulation of the renal Na-HCO3 cotransporter: IV. Mechanisms of the stimulatory effect of angiotensin II.

Angiotensin II stimulates proximal tubule acidification by activating both the Na-H antiporter and the Na-HCO3 cotransporter. The mechanism whereby angiotensin II stimulates the Na-HCO3 cotransporter was investigated in renal cortical basolateral membrane vesicles of the rabbit by measuring 22Na uptake in the presence of HCO3 and gluconate. Na-HCO3 cotransporter activity (expressed in nanomoles per milligram of protein per 3 s) was taken as the difference in 22Na uptake in the presence of HCO3 and gluconate. Angiotensin II stimulated Na-HCO3 cotransporter activity significantly (control, 1.5 +/- 0.4; angiotensin II, 3.3 +/- 0.6; P < 0.05), and this stimulation was prevented by the angiotensin II receptor antagonist DuP 753. Angiotensin II has been shown to stimulate both pertussis toxin-sensitive Gi protein and pertussis toxin-insensitive Gq protein. In the presence of pertussis toxin, angiotensin II (10(-11) M) failed to stimulate the Na-HCO3 cotransporter, suggesting a role of Gi protein in mediating this effect. In the presence of a polyclonal antibody against Gi protein, angiotensin II failed to stimulate the Na-HCO3 cotransporter (control, 1.6 +/- 0.4; angiotensin II, 3.9 +/- 0.9; angiotensin II + Gi, 1.2 +/- 0.7). Angiotensin II stimulated inositol triphosphate release, and this effect could be blocked by the phospholipase C inhibitor U73122, suggesting a role of phospholipase C or A2 in this effect of angiotensin II. In the presence of the protein kinase C inhibitor calphostin C (50 nM), angiotensin II also failed to stimulate the Na-HCO3 cotransporter. These results demonstrate that angiotensin II stimulates the renal Na-HCO3 cotransporter by interacting with a specific angiotensin II receptor and that this stimulation is mediated by the activation of Gi and Gq proteins.

Angiotensin II↗

PubMed1994

The morphologic changes of endometrial spiral arterioles in IUD-induced menorrhagia.

To investigate the relationship between IUD-induced menorrhagia and spiral arteriolar function, we examined the endometrium under light and electron microscope on samples obtained within 24 hours after the onset of premenstrual spotting. These samples included an IUD bleeding group (20 cases), an IUD non-bleeding group (20 cases) and an IUD non-user group (10 cases) as controls. Compared with the IUD non-user group the degenerative changes of spiral arteriolar wall were more severe and dilation of the spiral arteriolar lumen was more obvious, especially in the spongeous layer. In the IUD non-user group these changes were mild, suggesting that IUD-induced menorrhagia might be correlated with poor contractility of spiral arterioles in the spongeous layer.

Adult↗

PubMed1994

[Hyperfractionated irradiation for non-small cell lung cancer (NSCLC)--a phase III clinical trial].

From Dec. 1990 to Aug. 1991, 109 patients with NSCLC were randomized into two groups. The first was treated by hyperfractionated irradiation (HF) with 1.15-1.25Gy per fraction, twice daily (interval > or = 6 hrs between fractions), and total doses of 69.6 +/- 2.1Gy. The other was conventional irradiation (CF) with 1.8-2.0Gy per fraction, once a day, and total doses of 63.9 +/- 1.1Gy. All but 11 was included in the analysis. The results showed that HF, compared to CF, could improve immediate response rates in patients with squamous cell carcinoma or with tumor size of 3-6cm (P < 0.05). The comparison of 1 and 2 year survivals did not show significant difference, but 1 year local control rate was 47.3% in HF and 29.1% in CF, P < 0.05. Further stratified analysis showed that the 1 and 2 year local control rates in patients of HF in stage I-IIIa were 54%, 28%; 39%, 13% in patients of CF in stage I-IIIa, P < 0.05. The 1 and 2 year survival rates in patients in stage I-IIIa were 64%, 32% in HF; 18%, 6% in CF, (P < 0.05). An assessment of acute and late toxicity showed no significant difference in incidences between the two groups. It is concluded that HF, compared to CF, can improve 1 and 2 year survival and local control rates of patients in stage I-IIIa.

Adult↗

PubMed1993

Glucocorticoids and the renal Na-H antiporter: role in respiratory acidosis.

We examined the role of glucocorticoids in the activity of the renal brush border Na-H antiporter under baseline conditions (5% CO2 gassing) and during respiratory acidosis (10% CO2 gassing) in cultured monolayers of a proximal tubule suspension (primary cultures of the proximal tubule). Primary cultures of the proximal tubule showed an adaptive increase in renal brush border Na-H antiporter activity in response to respiratory acidosis in presence but not in the absence of physiologic concentrations of hydrocortisone in the medium. The effect of hydrocortisone to increase the activity of the renal brush border Na-H antiporter in respiratory acidosis could also be elicited by dexamethasone. Deletion of hydrocortisone from the medium also impaired the baseline activity of the Na-H antiporter. The effect of hydrocortisone to increase the activity of the Na-H antiporter under baseline conditions and during respiratory acidosis was elicited by physiologic concentrations of the hormone and 100-fold increase in concentration did not further increase the activity of the Na-H antiporter. These results demonstrate that the presence of physiologic concentrations of glucocorticoids are necessary for the baseline activity of the renal brush border Na-H antiporter and its adaptive increase in response to respiratory acidosis.

Acidosis, Respiratory↗

PubMed1993

Role of protein kinase C in the adaptive increase in Na-H antiporter in respiratory acidosis.

Chronic respiratory acidosis stimulates the Vmax of the renal brush border Na-H antiporter. The activation of protein kinase C (PKC) by phorbol esters stimulates the activity of the renal Na-H antiporter. In this study, the hypothesis that PKC plays a role in the adaptive increase of the renal brush border Na-H antiporter activity to respiratory acidosis was tested. In vivo respiratory acidosis was associated with an increase in in vitro Na-H antiporter activity and also with an increase in brush border membrane PKC activity, without changes in PKC activity in cytosol or basolateral membranes. Na-H antiporter activity, assessed as the amiloride-sensitive component of 22Na uptake, was measured in cultured proximal tubule cells exposed to 10% CO2 for 48 h. Na-H antiporter activity was significantly higher in cells exposed to 10% CO2 than in those exposed to 5% CO2. To evaluate the role of PKC, cultured cells were depleted of PKC by exposure to the active phorbol ester phorbol 12-myristate 13-acetate (PMA; 10(-7) or 10(-6) M) for 48 h before exposure to 10% CO2. In the presence of 10% CO2, Na-H antiporter activity was significantly lower in PKC-depleted cells than in control. In addition, sphingosine, an inhibitor of PKC, also prevented the adaptation of the Na-H antiporter to 10% CO2 as compared with 5% CO2. In cells treated with the inactive analog 4 alpha-PMA, 22Na uptake was not different than that in control. PMA-treated cells also had a decrease in Na-H antiporter activity during exposure to 5% CO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Respiratory↗

PubMed1992

Tumor necrosis factor alpha in the human ovary: presence in follicular fluid and effects on cell proliferation and prostaglandin production.

OBJECTIVE: To examine the concentration of tumor necrosis factor alpha (TNF alpha) in human follicular fluid (FF) and its effects on cultured human granulosa-lutein cells. DESIGN: The concentration of TNF alpha in FF from hyperstimulated cycles and in conditioned media from cultured granulosa-lutein cells was measured by radioimmunoassay (RIA) and bioassay using L929 cells. The effects of recombinant human TNF alpha (rTNF alpha) on proliferation and production of progesterone (P) and prostaglandin (PG, PGE2, and PGF2 alpha) by cultured human granulosa-lutein cells were assessed. SETTING: In vitro fertilization and embryo transfer (IVF-ET) program at Reproductive Medicine Unit, The Queen Elizabeth Hospital, Woodville, South Australia, Australia. PATIENTS: Twenty-five women undergoing IVF-ET for tubal factor infertility. RESULTS: The concentration of immunoreactive TNF alpha in FF was 0.36 +/- 0.02 microgram/L, and there were no significant correlations between levels of TNF alpha and steroids or FF volume. Bioactivity for TNF alpha was considerably less. Immunoreactive or bioactive TNF alpha was not detected in conditioned media from granulosa-lutein cell culture. Recombinant human TNF alpha dose-dependently stimulated proliferation of cultured granulosa-lutein cells as measured by incorporation of 3H-thymidine, but in contrast to earlier reports, we were not able to demonstrate any effect of rTNF alpha on basal or human chorionic gonadotropin-stimulated P accumulation during culture periods of up to 72 hours. The accumulation of both PGE2 and PGF2 alpha was dose-dependently increased by rTNF alpha during a 48-hour incubation period. Time course studies revealed that maximal levels of both PGE2 and PGF2 alpha were reached within 12 hours of culture. CONCLUSION: Immunoreactive and bioactive TNF alpha is present in FF. Tumor necrosis factor alpha may have a physiological role in stimulating proliferation of follicular cells and PG production at the time of ovulation and formation of the corpus luteum.

Cell Division↗

PubMed1992

Concentrations of immunoreactive interleukin-1 and interleukin-2 in human preovulatory follicular fluid.

The presence of immunoreactive interleukin-1 (IL-1) and interleukin-2 (IL-2) in human follicular fluid obtained at the time of oocyte collection for in-vitro fertilization was ascertained by radioimmunoassay. In group I (20 fluids from 20 patients), the concentrations of IL-1 were 0.9 +/- 0.06 and 1.9 +/- 0.04 (mean +/- SEM) fmol/l in follicular fluid and plasma respectively. A positive correlation existed between IL-1 levels in follicular fluid and plasma (r = 0.56, P less than 0.01). Concentrations of IL-2 were 3.5 +/- 0.2 and 6.1 +/- 0.3 fmol/l in follicular fluid and plasma respectively. A positive correlation of IL-2 levels was also found between follicular fluid and plasma (r = 0.65, P less than 0.01). There was no association between IL-1, IL-2 and steroid levels, regardless of whether they were compared in follicular fluid or plasma. Group II was composed of a series of fluids (two to seven samples for each of seven patients) in which the follicular concentrations of IL-1 and IL-2 did not show a positive correlation with the volume of follicular fluid or the concentrations of follicular fluid steroids. It is concluded that human preovulatory follicular fluid contains immunoreactive IL-1 and IL-2. The role of IL-1 and IL-2 in ovarian physiology remains to be determined.

Estradiol↗

PubMed1992

Distribution of leukocyte subpopulations in the human corpus luteum.

Cytokines, as secreted products of leukocytes, have roles in many organs of the body via paracrine or autocrine mechanisms. In the present study, we demonstrate by immunocytochemistry the leukocytes present in the human corpus luteum in order to investigate further the relationship between leukocytes, cytokines and corpus luteum function. Ten intact corpora lutea were collected from female patients who had no apparent ovarian disease. The mean age of these patients was 37 years (range 23-55 years). Frozen and paraffin sections were subjected to analysis using monoclonal antibodies which were specific to leukocyte marker antigens. The results showed that there are macrophages, cells positive for leukocyte common antigen (LCA), T lymphocytes including T helper/inducer (T4) cells, T cytotoxic/suppressor (T8) cells and activated T (Ta) cells (interleukin-2 receptor-positive cells), monocytes and natural killer (NK) cells but not B lymphocytes present in the human corpus luteum. The distribution of the leukocytes present in the different parts of the corpus luteum was found to be in the order: theca-luteal area greater than loose connective tissue area greater than granulosa-luteal area. Macrophages and T lymphocyte subsets comprised the main components of the total leukocytes in the human corpus luteum. Ta cells were only localized in the loose connective tissue of the corpus luteum. In most cases, macrophages, LCA cells and T4 cells tended to be situated in a single cell layer on the edge of the theca-luteal area and surrounding the granulosa-luteal area. These results suggest that the leukocytes may act to a greater extent in the theca-luteal area than in the granulosa-luteal area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Human monoamine oxidase A and B genes exhibit identical exon-intron organization.

Monoamine oxidases A and B [MAOA and MAOB; amine:oxygen oxidoreductase (deaminating) (flavin-containing), EC 1.4.3.4] play important roles in the metabolism of neuroactive, vasoactive amines and the Parkinsonism-producing neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Human MAOA and MAOB genes isolated from X chromosome-specific libraries span at least 60 kilobases, consist of 15 exons, and exhibit identical exon-intron organization. Exon 12 codes for the covalent FAD-binding-site and is the most conserved exon; the MAOA and MAOB exon 12 products share 93.9% peptide identity. These results suggest that MAOA and MAOB are derived from duplication of a common ancestral gene and provide insight on the structural/functional relationship of the enzyme products.

Base Sequence↗

PubMed1991

Lymphokines, including interleukin-2, alter gonadotropin-stimulated progesterone production and proliferation of human granulosa-luteal cells in vitro.

The effects of human interleukin-1 (IL-1) and IL-2 on human granulosa-luteal cell progesterone production were examined with or without hCG stimulation in vitro. Human granulosa-luteal cells were recovered from follicular fluid obtained from women undergoing in vitro fertilization procedures and cultured for up to 7 days before supernatant progesterone level measurement. Lymphokine-rich conditioned medium was prepared from mitogen-stimulated human peripheral blood leukocytes (HPL-CM). The influence of HPL-CM on both granulosa-luteal cell progesterone production and cell growth was inhibitory. In contrast, supernatants of the IL-2-producing cell line MLA-144 (MLA-CM) stimulated both basal progesterone secretion and cell proliferation. Human recombinant IL-2 (from 0.1-100 IU) alone did not change progesterone levels, compared to control values, after 24 h of cell culture. However, 1, 10, and 100 IU IL-2 significantly inhibited progesterone secretion from cells stimulated by 5 IU hCG (P less than 0.01). The enhanced progesterone levels stimulated by forskolin were also significantly inhibited by 10 IU IL-2 (P = 0.01). This effect was not mediated through decreased cAMP, since the forskolin-enhanced cAMP level was not influenced by IL-2, IL-1, with or without hCG, did not show any effect on progesterone production during either 24 or 48 h of cell culture. It is concluded that 1) human recombinant IL-2 significantly inhibits progesterone production stimulated by hCG in human granulosa-luteal cells; 2) IL-2 also had a marked inhibitory effect on forskolin-induced progesterone release, but did not influence the increased cAMP level stimulated by forskolin; 3) the inhibitory influence of IL-2 on progesterone synthesis may be down-stream in the signal transduction pathway from cAMP activation; and 4) HPL-CM and MLA-CM produced inhibitory and stimulatory effects, respectively, on both basal and hCG-stimulated progesterone levels as well as on granulosa-luteal cell proliferation. These activities cannot be completely attributed to IL-2, and other mediators of leukocyte origin may, therefore, exist.

Cell Division↗