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Biomedical subjects

S L Lee

Publications and source records attributed to S L Lee.

At least 127 records · Page 7Linked to original sources
PubMed1995

Thyroid peroxidase autoantibodies and their effects on enzyme activity in patients with systemic lupus erythematosus.

Thyroid microsomal antibodies (Ms-Ab) are recently proved to be directed to thyroid peroxidase (TPO). The aim of this study was to investigate whether the sera of patients with systemic lupus erythematosus (SLE) contain anti-TPO antibodies (TPO-Ab) and whether these antibodies influence enzyme activity. Sera from patient with Hashimoto's thyroiditis was also studied. Serum samples were obtained from 37 patients with SLE, 20 patients with Hashimoto's thyroiditis and 20 healthy subjects. TPO-Ab were detected by immunoprecipitation using crude microsomal preparations or enzyme-linked immunoabsorbent assay (ELISA) with recombinant TPO. Positive TPO-Ab by ELISA were found in 11 (61%) of 18 patients with lupus whose serum contained Ms-Ab. Low levels of TPO-Ab also were found in three (16%) of 19 lupus sera that did not contain Ms-Ab. All patients with Hashimoto's thyroiditis had high levels of TPO-Ab in serum. When measured by ELISA, TPO-Ab were highly correlated with the results of a TPO immunoprecipitation assay and with the titers of Ms-Ab in patients with lupus (r = 0.83, n = 18, P < 0.01; r = 0.63, n = 18, P < 0.01) and in Hashimoto's thyroiditis (r = 0.89, n = 20, P < 0.01; r = 0.75, n = 20, P < 0.01). When evaluating the direct influence of TPO-Ab on the activity of TPO, we found no significant inhibition of enzymatic activity in both guaiacol and iodide assays by lupus sera in contrast with sera from Hashimoto's thyroiditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Chemical and biological characterization of oxo-eicosatetraenoic acids.

Eicosatetraenoates (ETEs) with 5-oxo residues are known to induce human neutrophil (PMN) Ca2+ transients and chemotaxis. We find that 5-oxoETE, 5-oxo-8-trans-ETE, 5-oxo-15-hydroxy-ETE, 5-hydroxy-ETE, 5-hydroxy-15-oxoETE, 5,15-dioxoETE, and 5,15-dihydroxy-ETE have respective relative potencies of 10, 5, 3, 1, 0.2, 0.1, and 0.02 in: a) causing PMN to mobilize Ca2+, aggregate, and release small amounts of granule enzymes and b) promoting large degranulation and oxidative burst responses in PMN co-challenged with platelet-activating factor, tumor necrosis factor-alpha, or ATP. Contrastingly, 12(R)-hydroxy-ETE, 12(S)-hydroxy-ETE, and 12-oxoETE induced PMN Ca2+ transients and aggregation [respective potencies (5-hydroxy-ETE = 1) of 0.1, 0.01, and 0.003] but did not effect degranulation, and 15-hydroxy-ETE, 15-oxoETE, and 15-oxo-11-trans-ETE were inactive in all assays. Finally, 5-oxo/hydroxy-ETEs desensitized PMN to themselves but not to 12-oxo/hydroxy-ETEs or leukotriene (LT)B4; 12-oxo/hydroxy-ETEs and LTB4 desensitized PMN to themselves and each other but not to 5-oxo/hydroxy-ETEs; 15-oxo/hydroxy-ETEs did not desensitize PMN; and a LTB4 receptor antagonist blocked responses to LTB4 and 12-oxo/hydroxy-ETEs but not to 5-oxo/hydroxy-ETEs. Thus, 5-oxo/hydroxy-ETEs act by a common, LTB4 receptor-independent mechanism that recognizes 5- but not 12- or 15-oxo/hydroxy-ETEs and prefers oxo over hydroxy residues at C5 whereas 12-oxo/hydroxy-ETEs act via a LTB4 receptor mechanism that recognizes 12- but not 5- or 15-oxo/hydroxy-ETEs and prefers hydroxy over oxo residues at C12.

Arachidonic Acids↗
PubMed1994

Tissue-specific expression of Na(+)-Ca2+ exchanger isoforms.

The sodium-calcium exchanger (NCE) plays a critical role in diverse processes in many different tissues including heart, nerve, and kidney. Surprisingly, the NCE is encoded by a single gene. We have isolated and sequenced a rat renal NCE clone, denoted F1, that was identical to previous rat NCEs, except for two unique sequences: one in the 5'-untranslated region and the other at a site of alternative splicing in the coding sequence. To explore these regions further, we examined NCE transcripts in several tissues using "rapid amplification of cDNA 5'-ends" and polymerase chain reaction amplification. Three species were identified each with a different 5'-end exon spliced to a common NCE core at nucleotide -34 in the 5'-untranslated region. Based on Northern analysis, each of these species had a unique tissue distribution. Whereas the F1 5'-end variant was abundantly expressed only in kidney, a second variant was expressed mostly in heart, and the third variant was expressed ubiquitously elsewhere. Investigation of the region of alternative splicing in the coding sequence also revealed tissue-specific expression of five major species. These findings indicate that the NCE expression is controlled and regulated under the influence of different promoters in a tissue-specific fashion. Therefore, we propose that the structural complexity of the single NCE gene allows it to respond independently to the unique demands of different environments.

Alternative Splicing↗
PubMed1994

Effects of neurohypophyseal antagonists in postnephrectomy natriuresis in male rats.

Acute unilateral nephrectomy (AUN) in anesthetized male Lewis x DA rats induced rapid and consistent increases in electrolyte and fluid excretion by the remaining kidney during the first hours. Continuous infusion of a vasopressin (AVP) V1-receptor antagonist d(CH2)5Tyr(Me)AVP (V1-ant) reduced renal electrolyte and fluid excretion before and after AUN to a similar extent, whereas an oxytocin (OT)-receptor antagonist [Mpa1,D-Tyr(Et)2,Thr4,Orn8]-OT (CAP) at the same dose selectively attenuated the increase in sodium excretion after AUN. The plasma concentration of OT rose significantly after AUN (9.16 +/- 1.4 to 21.45 +/- 5.07 pg.ml-1). A similar OT level obtained by infusion of OT mimicked the renal responses to AUN without elevating blood pressure; however, only CAP but not V1-ant efficiently reversed OT-induced natriuresis. Also, the infusion of CAP at the same dose produced no effects on the rise of blood pressure caused by AVP while the infusion of the V1-ant prevented such a rise. Thus, CAP reduced the natriuresis after AUN by interfering with OT- and not V1-receptors. In conclusion, evidence is presented, for the first time, concerning the major role of OT receptors in the acute readjustment of the renal sodium excretion after AUN, and a synergistic role for AVP in terms of the general magnitude of renal excretion.

Animals↗
PubMed1994

Serotonin produces both hyperplasia and hypertrophy of bovine pulmonary artery smooth muscle cells in culture.

Serotonin [5-hydroxytryptamine (5-HT)] has a dual effect on bovine pulmonary artery smooth muscle cells (SMC) in culture (S.-L. Lee, W. W. Wang, B. J. Moore, and B. L. Fanburg. Circ. Res. 68: 1362-1368, 1991.). Cellular internalization of 5-HT stimulates DNA synthesis and cellular proliferation, whereas the action of 5-HT on a cell surface receptor elevates adenosine 3',5'-cyclic monophosphate and inhibits proliferation. The present study shows that 5-HT causes proliferation of both pulmonary artery and aortic SMC but not of endothelial cells or fibroblasts. Furthermore, c-myc and alpha- and beta-actin gene expressions of pulmonary artery SMC were elevated after 2-h incubation with 5-HT, before stimulation of [3H]thymidine incorporation. Actinomycin D (0.05 micrograms/ml) but not cycloheximide (1 microgram/ml) inhibited the gene expression produced by 5-HT. Growth-arrested SMC progressed from a G0 quiescent state through a normal cell cycle when subjected to 5-HT, 5-HT plus 25 ng/ml insulin-like growth factor, or 5-HT plus 0.5 ng/ml fibroblast growth factor. Cell number increased by 20-40% at 40 h and 50-140% at 7 days. Protein content of cells treated with 5-HT was elevated by 20-40% at 7 days, whereas the rate of protein synthesis, measured by [35S]methionine incorporation, increased by 50-70% at 24 h. In the presence of 1 microM 5-HT, cells enlarged by 70 and 100-200% at 40 h and 7 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1994

Regulation of serotonin-induced DNA synthesis of bovine pulmonary artery smooth muscle cells.

We have previously reported that serotonin [5-hydroxytryptamine (5-HT)] stimulates DNA synthesis of bovine pulmonary artery smooth muscle cells (SMC) by its high-affinity uptake. Uptake inhibitors, but not selective 5-HT receptor antagonists, prevented the stimulatory effect (S.-L. Lee and B. L. Fanburg. J. Cell. Physiol. 150:396-405, 1992). We have now further evaluated the mechanism by which 5-HT enhances SMC DNA synthesis. Although some serotonergic agonists mimicked this stimulation, selective 5-HT receptor agonists produced no or only minor and variable stimulatory effects. The action of 5-HT was not inhibited by inhibitors of phospholipases C and A2, the protein kinase C (PKC) inhibitors dihydrosphingosine and 1-(-isoquinolinylsulfonyl)-2 methylpiperazine (H-7), or down-regulation of PKC with phorbol 12,13-dibutyrate. Staurosporine, a reputed PKC and tyrosine kinase (TK) inhibitor, and genistein, a selective TK inhibitor, reversed the stimulatory effect of 5-HT in a dose-dependent manner. Before stimulation of thymidine incorporation into cellular DNA, 5-HT elevated c-myc and actin mRNAs. Imipramine, fluoxetine, staurosporine, and cholera toxin inhibited the stimulations of both DNA synthesis and c-myc and actin mRNA expressions by 5-HT. Thus the data support a concept that 5-HT-induced thymidine incorporation by SMC involves membrane transport of 5-HT that initiates tyrosine phosphorylation.

Actins↗
PubMed1994

Antithrombin III enhances the motility and chemotaxis of boar sperm.

Purified porcine antithrombin III stimulates motility and acts as a chemoattractant of washed boar sperm. Porcine follicular fluid and blood plasma both possess chemotactic activity. Porcine antithrombin III-immunoreactive molecules are distributed on the zona pellucida of ovulated eggs flushed from the swine oviducts. We propose that antithrombin III plays important roles in the mammalian fertilization process in vivo.

Animals↗
PubMed1994

The involvement of extracellular proteinases and proteinase inhibitors in mammalian fertilization.

Extracellular proteinases and proteinase inhibitors have been known to play many important roles in various biological systems. They are also important for reproductive functions of the mammals. Kallikrein stimulates human sperm motility. Porcine antithrombin III (AT III) has been identified to be a sperm-motility-stimulating protein and a chemoattractant for boar sperm. AT III-immunoreactive molecules are also detected on the zona pellucida of ovulated porcine eggs and are suggested to act as a sperm receptor. Proteinase inhibitors in the seminal plasma act as decapacitation factors. Both the proteinase inhibitors in the seminal plasma and the trypsin-like protein(s) on the surface of the sperm head play important roles in the sperm-egg interaction. The trypsin-like protein(s) are also involved in the induction of acrosome reaction. Plasminogen activator was demonstrated to be a trigger of the zona reaction. In summary, the roles of extracellular proteinases and proteinase inhibitors in the mammalian fertilization process are diversified and worthy of further investigation.

Acrosome↗
PubMed1993

Modification of human sperm function by human follicular fluid: a review.

This review assesses whether human follicular fluid (hFF) is able to modify human sperm function in vitro. Addition of hFF has been found to stimulate the motility of washed human spermatozoa, to increase the percentage of hyperactivated spermatozoa, to induce the acrosome reaction, to attract spermatozoa to the site of fertilization and to facilitate penetration of the oocyte by spermatozoa. It is possible that hFF could provide a favourable environment around the oocyte for fertilization by spermatozoa. Inclusion of hFF in gamete transfer medium may also improve the success rate of assisted reproduction technology. Purification of individual components in hFF which modify different aspects of sperm function awaits further investigation.

Animals↗
PubMed1993

Anticentromere antibodies in subjects with no apparent connective tissue disease.

OBJECTIVES: To study the association of anticentromere antibodies (ACA) in various diseases. METHODS: A total of 4800 consecutive serum samples were tested for ACA by indirect immunofluorescence using HEp-2 cells as substrates and by immunoblotting of Molt-4 cell mitotic chromosomal antigens and recombinant CENP-B protein. RESULTS: Anticentromere antibodies were identified in the serum samples of 24 subjects, including eight without apparent connective tissue diseases, six with primary biliary cirrhosis, two with diffuse scleroderma, one with pulmonary hypertension, one with primary Raynaud's phenomenon, one with CREST syndrome (calcinosis, Raynaud's phenomenon, oesophageal dysmotility, sclerodactyly, telangiectasia), and five with other connective tissue diseases. By immunoblotting using Molt-4 cells mitotic chromosomal antigens three centromere antigens were recognised by these serum samples. These were: CENP-A (17 kilodalton recognised by 22 of 24 ACA positive serum samples); CENP-B (80 kilodalton recognised by 22 of 24 ACA positive serum samples); and CENP-C (140 kilodalton recognised by 19 of 24 ACA positive serum samples). There was no specific pattern for serum samples from patients with different groups of diseases on immunoblotting. Recombinant CENP-B proteins were all recognised by these samples. Patients without apparent connective tissue disease often had a lower ACA titre than patients with primary biliary cirrhosis. CONCLUSIONS: These data suggest that a positive result for ACA does not always indicate the presence of a connective tissue disease.

Adult↗
PubMed1993

Cu,Zn superoxide dismutase in vascular cells: changes during cell cycling and exposure to hyperoxia.

Conditions that generate reactive oxygen species elevate Cu,Zn superoxidase dismutase (SOD) in endothelial cells (EC) concomitant with decreased cellular proliferation. The current studies were undertaken with both vascular EC and smooth muscle cells (SMC) to compare the influences of cellular proliferation with those of hyperoxia on induction of Cu,Zn SOD. To assess cell cycling alone, EC and SMC were growth arrested, then released from arrest. Cell cycling was monitored by [3H]thymidine incorporation, counts, and flow cytometry. SOD catalytic activity was measured spectrophotometrically and SOD protein by enzyme-linked immunosorbent assay. A digoxigenin-labeled probe was used to quantify SOD mRNA by Northern analysis. EC reached the S phase of the cell cycle in 18 h and completed one cycle in 24-30 h, whereas SMC took 24-30 h to reach the S phase and 48 h to complete one cycle. Cu,Zn SOD mRNA for both EC and SMC was very low during the Go/G1 phase, peaked during the S phase, and then reverted to lower values as cells progressed through their cycles. Cu,Zn SOD activity and immunoprotein content showed corresponding changes to those of mRNA. Exposure to hyperoxia (95% O2) delayed the entry of released cells into the S phase of the cell cycle and blocked the cells in the S or G2 phase, but induced Cu,Zn SOD mRNA before the S phase and caused persistence of elevation of Cu,Zn SOD mRNA as cells progressed through their cycles. Exposure to hyperoxia also induced Cu,Zn SOD mRNA in growth-arrested cells within 24-48 h. Thus our studies support roles for both cells cycle dependency and reactive oxygen species in the induction of Cu,Zn SOD.

Animals↗
PubMed1992

Ca(2+)-channels and adrenoceptors in diabetic skeletal muscle.

The status of Ca(2+)-channels and adrenoceptors in the hind leg skeletal muscle was examined in rats 8 weeks after inducing diabetes by an intravenous injection of streptozotocin (65 mg/kg). Scatchard plot analysis of the data on specific binding of 3H-nitrendipine with crude membranes from diabetic muscle revealed an increase in the density of Ca(2+)-channels without any significant change in their affinity for the ligand. An increase in the density of beta-adrenoceptors without any alteration in their affinity, as measured by 3H-dihydroalprenolol binding, was also evident in the diabetic muscle. The observed increase in the number of Ca2+ channels or beta-adrenoceptors seems specific since no change in the alpha-adrenoceptor density or affinity, as measured by 3H-prazosin binding, was seen in the diabetic membranes. These results support the view that higher activities of Ca2+ transport systems or regulatory mechanisms may be associated with hyperfunction of the diabetic skeletal muscle.

Animals↗
PubMed1992

Alterations in Ca(2+)-channels during the development of diabetic cardiomyopathy.

In order to examine the status of Ca2+ channels in heart sarcolemma during the development of diabetes, rats were injected intravenously with 65 mg/kg streptozotocin and hearts were removed 1, 3 and 8 weeks later. Crude membranes from the ventricular muscle were prepared and the specific binding of 3H-nitrendipine was studied by employing different concentrations of this Ca(2+)-antagonist. A significant decrease in both dissociation constant and maximal number of 3H-nitrendipine binding was observed in 3 and 8 weeks diabetic preparations. No such alterations were evident in diabetic brain membranes. Treatment of diabetic animals with insulin prevented the occurrence of these changes in the myocardium. The altered 3H-nitrendipine binding characteristics in diabetic heart membranes may not be due to the high levels of circulating catecholamines in this experimental model because no such changes were seen upon injecting a high dose (40 mg/kg) of isoproterenol in rats for 24 hr. The reduced number of 3H-nitrendipine binding sites may decrease Ca(2+)-influx through voltage sensitive Ca2+ channels and partly explain the depressed cardiac contractile force development in chronic diabetes whereas the increased affinity of Ca2+ channels may partly explain the increased sensitivity of diabetic heart to Ca2+.

Animals↗
PubMed1992

Serotonin produces a configurational change of cultured smooth muscle cells that is associated with elevation of intracellular cAMP.

Early passaged bovine pulmonary artery smooth muscle cells (SMC) respond to serotonin (5-HT) by developing a reversible change in configuration. (Lee et al. J. Cell. Physiol. 138:145, 1989). This configurational change does not occur in pulmonary artery endothelial cells (EC) subjected to 5-HT and is adenosine triphosphate (ATP) dependent, lost with passage of SMC, and inhibited by various agents that block high-affinity 5-HT uptake. We now report a second configurational change (also dendritic formation) of SMC produced by 5-HT only in the presence of isobutylmethylxanthine (IBMX), an inhibitor of phosphodiesterase. This configurational change was also ATP dependent, but unlike the first response, (Lee et al., 1989), it occurred in both first and later passaged SMC and was not inhibited by blockade of 5-HT uptake. Also, unlike the response with 5-HT alone that failed to elevate cAMP, this one was associated with a large elevation of cAMP (eight fold above control values), similar to the response to the beta-agonist isoproterenol, plus IBMX. The second response was not blocked by a variety of 5-HT receptor antagonists but was reproduced by (+/-)-8-hydroxy-DPAT HBr (8-OH-DPAT), a reputed 5-HT1A agonist. The response was not dependent upon Ca2+ and was blocked by 1-2 mM n-phenylanthranilic acid or anthracene-9-carboxylic acid, electrically conductive Cl- channel inhibitors. Hence, 5-HT in the presence of IBMX causes a marked elevation of cAMP of SMC and this elevation in cAMP likely results in a cellular configurational change through a Cl- channel-dependent mechanism similar to that we previously described for EC in the presence of beta-adrenergic agonist stimulation (Ueda et al. Circ. Res. 66:951, 1990). EC do not show a similar response to 5-HT possibly because cAMP is not adequately elevated, even in the presence of IBMX, to enhance Cl- channel activity. We propose that our observations indicate the presence of two sites of action of 5-HT on the smooth muscle cell, one intracellularly and another at a cell surface receptor.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Investigation of the substrate binding and catalytic groups of the P-C bond cleaving enzyme, phosphonoacetaldehyde hydrolase.

Kinetic studies with substrate analogs and group-directed chemical modification agents were carried out for the purpose of identifying the enzyme-substrate interactions required for phosphonoacetaldehyde (P-Ald) binding and catalyzed hydrolysis by P-Ald hydrolase (phosphonatase). Malonic semialdehyde (Ki = 1.6 mM), phosphonoacetate (Ki = 10 mM), phosphonoethanol (Ki = 10 mM), and fluorophosphate (Ki = 20 mM) were found to be competitive inhibitors of the enzyme but not substrates. Thiophosphonoacetaldehyde and acetonyl phosphonate underwent phosphonatase-catalyzed hydrolysis but at 20-fold and 140-fold slower rates, respectively, than did P-Ald. In the presence of NaBH4, acetonyl-phosphonate inactivated phosphonatase at a rate exceeding that of its turnover. Sequence analysis of the radiolabeled tryptic peptide generated from [3-3H]acetonylphosphonate/NaBH4-treated phosphonatase revealed that Schiff base formation had occurred with the catalytic lysine. From the Vm/Km and Vm pH profiles for phosphonatase-catalyzed P-Ald hydrolysis, an optimal pH range of 6-8 was defined for substrate binding and catalysis. The pH dependence of inactivation by acetylation of the active site lysine with acetic anhydride and 2,4-dinitrophenyl acetate evidenced protonation of the active site lysine residue as the cause for activity loss below pH 6. The pH dependence of inactivation of an active site cysteine residue with methyl methanethiol-sulfonate indicated that deprotonation of this residue may be the cause for the loss of enzyme activity above pH 8.

Amino Acid Sequence↗
PubMed1992

Serum cholesterol levels in a multiracial sample of 7,439 preschool children from Arizona.

BACKGROUND: The distribution and correlates of serum levels of total cholesterol were studied in cross-sectional analyses of 7,439 1 to 4 year olds examined through the Arizona Department of Health Services. RESULTS: Mean cholesterol levels increased with age, and levels among 2 year olds approached those seen in adolescents. Racial and ethnic differences in cholesterol levels were observed: mean (age-adjusted) levels were 147 mg/dl among American Indians (n = 622), 153 mg/dl among Hispanics (n = 3165), 154 mg/dl among non-Hispanic whites (n = 3448), and 163 mg/dl among blacks (n = 204). Cholesterol levels were not associated either with obesity, as assessed by relative weight or the Quetelet index, or with breast-feeding during infancy. Very overweight (greater than or equal to 20 kg/m2) 3 and 4 year olds, however, tended to have higher mean levels of cholesterol than did other children. The proportion of children with borderline (170 to 199 mg/dl) or high (greater than or equal to 200 mg/dl) levels of cholesterol varied by race/ethnicity: borderline (high) levels were seen among 14% (3%) of American Indians and 29% (11%) of blacks. The proportions of white and Hispanic children having cholesterol levels between 170 and 199 mg/dl or greater than or equal to 200 mg/dl were midway between those seen among American Indians and blacks. CONCLUSION: Additional information on the interrelationships of lipids and lipoproteins may aid in the identification of children who will be at increased risk for cardiovascular disease in adulthood.

Age Factors↗