Radiation and chemotherapy-associated fatigue.
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Antineoplastic Agents↗
Biomedical subjects
C Lee
Publications and source records attributed to C Lee.
Site-selective differences in cytochrome P450 isoform activities. Comparison of expression in rat and rhesus monkey lung and induction in rats.
The distribution of pulmonary cytochrome P450 (P450 or CYP) isoforms has been investigated primarily in immunohistochemical studies, which are neither quantitative nor reflective of the functions of these enzymes. Studies of enzyme activities have been performed using whole-lung homogenates or isolated cells, but there is little information on the regioselective expression of P450 monooxygenases. The aims of this study were to compare the activities of P450 monooxygenases in different lung subcompartments in two commonly studied animal models, i.e. rats and monkeys, and to explore the possibility that inducing agents would result in activity up-regulation that is highly site-selective, using rats as a model. Microdissection techniques were used to separate the airways from blood vessels and lung parenchyma. In rats, CYP1A1 (ethoxyresorufin) and CYP2B (pentoxyresorufin) dealkylase activities were highest in the parenchyma, whereas CYP2E1 (p-nitrophenol) hydroxylase activity was highest in the airways. P450 reductase activities were similar in airways and parenchyma and were lower in trachea. In monkeys, no significant site-selective differences in CYP1A1 and CYP2B1 activities were found. In contrast, CYP2E1 activity was higher in the distal bronchioles and parenchyma than in the proximal airways. P450 reductase activities were similar in microsomes prepared from all subcompartments of monkey lung. Induction of rat CYP1A1 activity by beta-naphthoflavone (administered ip) was much greater in the airways and lung parenchyma ( approximately 30-fold) than in the liver ( approximately 10-fold) or trachea ( approximately 2.5-fold). Oral administration of phenobarbital or acetone increased CYP2B and CYP2E1 activities in rat liver but had no significant effect on P450 activities in subcompartments of rat lung. These findings support the conclusion that there are regiospecific and species-specific differences in the activities of P450 isoforms and that the inducibility of rat pulmonary P450s is dependent on the isoform and lung region.
Animals↗
Liposomes enriched in oleic acid are less susceptible to oxidation and have less proinflammatory activity when exposed to oxidizing conditions.
As there is frequently a reciprocal relationship between oleic acid and linoleic acid content in LDL after dietary supplementation, it is difficult to determine the independent effects of oleic and linoleic acid on LDL oxidation. It is also unknown whether monounsaturated fatty acid enrichment might reduce the generation of proinflammatory products that occur when the polyunsaturated fatty acid-rich phospholipids within lipoproteins undergo mild oxidation. To address these issues, we exposed liposomes containing variable amounts of oleic, linoleic, and arachidonic acid to oxidizing conditions. Liposomes enriched in oleic acid but with constant amounts of linoleic acid were less susceptible to oxidation and had significantly greater lag times and time to half maximum conjugated diene formation. When mildly oxidized, liposomes containing either linoleic acid or arachadonic acid increased monocyte chemotaxis and monocyte adhesion to endothelial cells nearly 5-fold, demonstrating that oxidation products of both these polyunsaturated fatty acids are bioactive. The addition of a platelet activating factor receptor antagonist to endothelial cells inhibited stimulation of monocyte adhesion by oxidized liposomes, suggesting that some bioactive oxidation products of polyunsaturated fatty acids may resemble platelet activating factor in structure. In contrast, when liposomes were enriched in oleic acid, monocyte chemotaxis and monocyte adhesion were nearly completely inhibited. These results suggest that enriching lipoproteins with oleic acid may reduce oxidation both by a direct "antioxidant"-like effect and by reducing the amount of linoleic acid available for oxidation as well as reduce the generation of bioactive particles that occur during mild oxidation.
Animals↗
An in vitro bovine pericardial hemocompatibility testing system.
BACKGROUND AND AIMS OF THE STUDY: Bovine pericardium has been used as a biomaterial for heart valves since the late 1960s. Cross-linking agents have been applied routinely to reduce host-tissue response, including antigenicity, and to improve tissue leaflet durability. Evaluation of improvements in bovine pericardial valve leaflet calcification and flexibility require that in vitro systems be developed to correlate data with results from in vivo studies. This study describes an in vitro test system used to evaluate the effects of two surface-modifying treatments on pericardial tissue hemocompatibility. METHODS: Non-fixed and glutaraldehyde fixation-processed (GA) bovine pericardial tissues were exposed to anticoagulated whole blood for 60 min. Blood was then removed, and platelet-poor plasma prepared and frozen at -70 degrees C until analyzed for kallikrein activation and release of platelet factor 4 (PF4). Blood-exposed tissue samples were analyzed for fibrin (ogen) binding with an anti-fibrinogen antibody and for tissue cellular responsiveness (blood cell adherence and aggregation) by scanning electron microscopy. RESULTS: Conditions were determined for minimum extent of pumping action by the minicam system required to allow for solution movement while not tearing or wearing the tissue. A blood-tissue exposure time of 60 min provided sufficient first-pass exposure to evaluate the acute blood-tissue response. The relative degree of both kallikrein activation and PF4 release was greater in the non-fixed tissue but a greater number of fibrin(ogen) molecules per cm2 was found on GA-treated tissue. Scanning electron microscopy showed a differential cell response of non-fixed tissue compared with GA-treated tissue. CONCLUSION: This non-static test system demonstrated great promise for use in routine in vitro hemocompatibility testing of blood-contacting biological biomaterials.
Animals↗
Loss of expression of transforming growth factor-beta receptors is associated with poor prognosis in prostate cancer patients.
Transforming growth factor beta (TGF-beta) is a potent inhibitor of proliferation in most cells and exerts its effects through an interaction with membrane receptors type I (TGF-betaRI) and type II (TGF-betaRII). Recently, we have demonstrated a correlation between the loss of expression of TGF-betaRI and TGF-betaRII and increasing Gleason score in archival human prostate cancer tissues. To evaluate the potential prognostic value of this observation, the present study investigated the expression of TGF-beta receptors in association with disease progression after the initial diagnosis in 52 archival human prostate cancer tissues. The expression of both TGF-betaRI and TGF-betaRII was correlated with the Gleason score, clinical tumor stage, 4-year survival rate, and serological recurrence rate after radical prostatectomy. Results revealed that there was a significant association between the Gleason score and the loss of expression of TGF-betaRI (P < 0.025) and TGF-betaRII (P < 0.01). However, only the loss of TGF-betaRI expression showed a statistically significant association with the clinical tumor stage (P < 0.05), 4-year survival rate (P < 0.05), and serological recurrence rate after radical prostatectomy (P < 0.025). Therefore, these data indicate that the loss of TGF-betaRI expression as measured by immunohistochemical staining may be a potential prognostic marker in prostate cancer patients.
Humans↗
Prostate innervation.
The growth of the prostate gland has been considered to be controlled exclusively by endocrine means. The abundance of alpha adrenergic and muscarinic receptors and nerve fibers suggests that the autonomic nervous system may in fact play a role in the growth maturation and secretory functions of the prostate. The predominant adrenergic input to the prostate is from short adrenergic neurons, while cholinergic nerves are closely related to the glandular epithelium, presumably affecting a secretory function. The prostate has a high density of alpha-1 and beta-2 adrenergic receptors, and the presence of these receptors, as well as their regulation by androgens, suggests and supports the direct mitogenic effect of catecholamines on prostate growth. The activated signal transduction pathways in these neural systems also appear to modulate prostatic function and growth. Denervation of the prostate results in a loss of functional and structural integrity of the gland. The effects of sympathectomy and parasympathectomy support the conclusion that the dichotomy of function in prostatic autonomic innervation has a fundamental regulatory purpose. The majority of the afferent innervation to the ventral prostate is localized to sensory nerves from the L5 and L6 segments. There is some smaller degree of innervation from T13-L2. There is evidence of extensive bilateral innervation of pelvic viscera. Despite the importance of afferent sensory feedback in regulating the control of prostate growth, its effect is of a smaller magnitude than that observed with androgens. Regardless of the specific control mechanisms suggested by neural involvement in the growth differentiation and secretory function of the prostate, the presence of innervation appears to be consistent and reproducible, and holds great potential for increasing our understanding of pathologic influences in prostate disease.
Animals↗
Interleukin-8-induced suppression of polymorphonuclear leukocyte apoptosis is mediated by suppressing CD95 (Fas/Apo-1) Fas-1 interactions.
BACKGROUND: Neutrophil apoptosis is crucial in the resolution of inflammation. The role of interleukin (IL)-8 in neutrophil apoptosis has not been previously studied; we hypothesized that in addition to its role as a chemoattractant, IL-8 would regulate polymorphonuclear leukocyte (PMN) apoptosis. METHODS: PMNs were adhered to plastic during hypoxia or normoxia and treated with IL-8 dosages of 0 to 1000 ng/mL. Apoptosis was assessed by cellular histology and the TUNEL assay. For receptor inhibition, blocking antibodies to IL-8 receptors in the presence of IL-8 were added. Apoptosis of PMNs treated with anti-Fas antibody +/- IL-8 was also analyzed. RESULTS: After treatment with 100 ng/mL IL-8 apoptosis was decreased from an average of 39.1% 9.3%. Inhibition of IL-8RA was able to restore apoptosis to 59.4%. Western analysis showed that with IL-8, there was a marginal decrease of total Fas protein, whereas Fas ligand was increased. After incubation with an apoptosis inducing-Fas antibody plus IL-8 reduced apoptosis to 9.5%. CONCLUSIONS: IL-8 not only promotes the inflammatory response by recruiting PMNs but also acts to suppress apoptosis mainly through the IL-8RA in an oxygen tension independent manner. The reduction in apoptosis is associated with changes in Fas and FasL where the presence of IL-8 suppresses the proapoptotic function of Fas-FasL interactions.
Adaptor Proteins, Signal Transducing↗
Intraorbital squamous epithelial cyst: an unusual complication of Silastic implantation.
Thin Silastic sheet alloplasts (Dow Corning, Midland, MI, U.S.A) are commonly used to reconstruct posttraumatic orbital floor defects. Complications associated with orbital Silastic implantation include infection, migration, and extrusion. The authors report an unusual case of an intraorbital, squamous, epithelial-lined cyst appearing as progressive vertical globe dystopia and proptosis occurring after Silastic reconstruction of a traumatic orbital floor defect.
Bone Cysts↗
Absence of expression of transforming growth factor-beta type II receptor is associated with an aggressive growth pattern in a murine renal carcinoma cell line, Renca.
Transforming growth factor-beta1 (TGF-beta1) inhibits the proliferation of many cancer cells. However, tumor cells frequently become resistant to this inhibitory effect due to the absence of TGF-beta receptor (TbetaR) expression. This study reports the nature of TGF-beta sensitivity in an aggressive murine renal carcinoma cell line, Renca, investigated in a series of experiments. The growth of Renca cells, in tissue culture, was not sensitive to the inhibitory effect of TGF-beta1 with doses ranging from 0.1 to 10 ng./ml., nor was this cell line sensitive to the effect of TGF-beta1 in inducing the expression of plasminogen activator inhibitor-I. Renca cells expressed TGF-beta1 mRNA and protein, as determined by RT-PCR and ELISA, respectively. The level of TGF-beta1 production by Renca cells was moderate, thus eliminating the possibility that endogenous TGF-beta1 production might be masking the effect of TGF-beta sensitivity. Furthermore, Renca cells expressed TbetaR-I mRNA, but did not express TbetaR-II mRNA, suggesting that the absence of this receptor may be the cause of TGF-beta insensitivity. Additionally, a vector containing the TbetaR-II cDNA was transiently transfected into Renca cells. The inhibitory effect of TGF-beta1 was introduced in Renca cells after transfection with this receptor. At the same time, the growth rate of these cells diminished significantly when compared with that of the wild type Renca cells, as judged by the rate of [3H]-thymidine incorporation in the absence of any exogenous TGF-beta1. These observations demonstrated that Renca cells lack the functional TbetaR-II and suggest that their aggressive growth pattern is due, at least in part, to their insensitivity to TGF-beta.
Animals↗
Estrogen receptors and glucocorticoid receptors in human well-differentiated thyroid cancer.
Previously, we and others have found that the prognosis of patients with well differentiated thyroid cancer is related to patient age and gender. In this study, we examined estrogen and glucocorticoid receptors in thyroid cancers and adjacent non-neoplastic thyroid tissues from 31 Chinese patients. Our results indicate that the level of estrogen and glucocorticoid receptors in thyroid cancer tissues was similar to that in non-neoplastic thyroid tissues. Significant higher estrogen and glucocorticoid receptor levels were found in thyroid cancers from men than women. There was no difference in estrogen receptor levels from thyroid cancer in women less than or older than 45. However, the level of glucocorticoid receptor in thyroid cancer from women less than 45 years old was significantly higher than that of women older than 45. Estrogen or glucocorticoid receptor levels did not correlate with tumor invasiveness. The pathobiological role of glucocorticoid receptors in thyroid cancer is not known but may be involved in changes in circadian rhythm of thyroid tumors.
Journal Article↗
High cost, low volume care: the case of haemophilia.
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Blood Coagulation Factors↗
Prostatic ductal system in rats: tissue-specific expression and regional variation in stromal distribution of transforming growth factor-beta 1.
BACKGROUND: Regional variations in stromal-epithelial interactions, mediated through soluble growth factors, may be responsible for differences in epithelial growth and death observed between regions of the rat prostatic ductal system. Since transforming growth factor-beta 1 (TGF-beta 1) can induce prostatic epithelial cell death in vitro and in vivo, we examined the localization and production of TGF-beta 1 with respect to the functional regions of the rat prostatic ductal system. METHODS: The distribution of TGF-beta 1 in the rat ventral prostate was examined by immunohistochemistry. Cell type-specific expression of TGF-beta 1 was determined using RT-PCR analysis of prostate epithelial and stromal cell fractions separated by Percoll gradient centrifugation. RESULTS: Immunohistochemical staining of normal prostate revealed regional variations in stromal TGF-beta 1 protein, which was most abundant in the stroma surrounding the degenerative proximal ducts. TGF-beta 1 staining was also tightly associated with the prostatic smooth muscle. Results of RT-PCR experiments confirmed the major source of TGF-beta 1 mRNA in normal rat prostate to be the stroma, with lesser expression by the epithelium. CONCLUSIONS: Stromal TGF-beta 1 was associated with cell death in the adjacent epithelial cell compartment in the prostatic ductal system, and alpha-smooth muscle actin-positive stromal cells may play a negative growth-regulatory role in the rat ventral prostate through production of TGF-beta 1.
Animals↗
High frequency of genetic instability of microsatellites in human prostatic adenocarcinoma.
In order to investigate the genomic instability associated with prostate cancer, 36 microsatellite marker loci on chromosomes 1p, 3p, 5q, 8p, 8q, 9p, 11q and 13q were analyzed using microdissected samples from prostate cancer and adjoining microscopically normal tissues from the same slide. DNA was extracted from the normal and tumor cells of 40 microdissected prostate-cancer samples, amplified by PCR, and analyzed for microsatellite instability (MSI) using 36 different polymorphic DNA markers. In the present study, we have utilized a highly refined technique of PCR product separation on a sequencing gel, developed in our laboratory, which clearly shows high-quality results for the microsatellite instability in prostate cancer. The results of this study suggest that 45% (18 out of 40) showed genomic instability at a minimum of 1 locus; 4 cases each showed MSI at one and 2 loci, 4 cases had MSI at 3 loci, 3 cases showed MSI at 5 loci, while one case each showed MSI at 7, 8 and 15 loci. There was no significant correlation between the MSI and stage or grade of the tumors. This extensive study on genomic instability in prostate cancer found the occurrence of MSI to be very high, which suggests a role of MSI in the pathophysiology of prostate cancer.
Adenocarcinoma↗
Epidermal growth factor-related peptides in human prostatic fluid: sources of variability in assay results.
BACKGROUND: Prostatic fluid (PF) provides a unique medium for noninvasive evaluation of critical growth and differentiation signals in the prostatic microenvironment. The purpose of this study was to establish the feasibility of measuring two prostatic mitogens, epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) in PF, and specifically to quantify extraneous variability attributable to the assay itself, sample handling, or biological variation within an individual over time. METHODS: PF was collected by transrectal massage from consecutive patients attending a urology clinic. Pooled PF and individual samples from 25 men with stable benign prostatic hyperplasia (BPH) were analyzed for EGF and TGF-alpha by radioimmunoassay and for total protein. RESULTS: Reproducibility was adequate at dilutions as low as 1:50 (2-microliter pooled sample) and 1:5 (20 microliters) for EGF and TGF-alpha, respectively. Results were not affected by freeze-thaw cycles, time in storage, or protease inhibition in fresh PF. EGF and TGF-alpha were detectable in 100% and 92% of individual men, with respective means of 152 and 0.2 ng/ml. Correlations between two samples obtained from the same man within 12 months were highly significant (EGF r = 0.89, TGF-alpha r = 0.71). Protein concentrations were consistent over time; expression of either peptide per weight of protein rather than per volume did not improve within-man correlation. Between-man variability far exceeded within-man variability for both peptides, and was estimated to account for 84% and 61% of the total variability in EGF and TGF-alpha, respectively. There was no correlation between EGF and TGF-alpha in the same samples. CONCLUSIONS: We conclude that men with BPH secrete consistent and distinct levels of EGF-related peptides in PF, and that these levels can be detected with acceptable sensitivity and precision by radioimmunoassay (RIA). Measurement of TGF-alpha, which has not been reported previously, requires a relatively larger sample.
Analysis of Variance↗
Specific T cell recognition of kinetic isomers in the binding of peptide to class II major histocompatibility complex.
Helper T cells are triggered by molecular complexes of antigenic peptides and class II proteins of the major histocompatibility complex. The formation of stable complexes between class II major histocompatibility complex proteins and antigenic peptides is often accompanied by the formation of a short-lived complex. In this report, we describe T cell recognition of two distinct complexes, one short-lived and the other long-lived, formed during the binding of an altered myelin basic protein peptide to I-Ak. One myelin basic protein-specific T cell clone is triggered by only the short-lived complex, and another is triggered by only the stable complex. Thus, a single peptide bound to a particular class II molecule can activate different T cells depending on the conditions of the binding reaction.
Animals↗
A DNA helicase from Schizosaccharomyces pombe stimulated by single-stranded DNA-binding protein at low ATP concentration.
A DNA helicase named DNA helicase I was isolated from cell-free extracts of the fission yeast Schizosaccharomyces pombe. Both DNA helicase and single-stranded DNA-dependent ATPase activities copurified with a polypeptide of 95 kDa on an SDS-polyacrylamide gel. The helicase possessed a sedimentation coefficient of 6.0 S and a Stokes radius of 44.8 A determined by glycerol gradient centrifugation and gel filtration analysis, respectively. From these data the native molecular mass was calculated to be 110 kDa, indicating that the active enzyme is a monomer. The DNA-unwinding and ATP hydrolysis activities associated with DNA helicase I have been examined. One notable property of the enzyme was its relatively high rate of ATP turnover (35-50 molecules of ATP hydrolyzed/s/enzyme molecule) that may contribute to its inefficient unwinding activity at low concentrations of ATP (<0.2 mM). Addition of an ATP-regenerating system to the reaction mixture restored the DNA-unwinding activity of the enzyme. S. pombe single-stranded DNA-binding protein (SpSSB, also called SpRPA) stimulated the DNA helicase activity significantly at low levels of ATP (0.025-0.2 mM) even in the absence of an ATP-regenerating system. In contrast, SpRPA had no effect on ATP hydrolysis at any ATP concentration examined. These observations suggest that the stimulation of DNA unwinding by SpRPA is not simply a result of suppression of nonproductive ATP hydrolysis. Rather, the role of SpRPA is to lower the Km for ATP in the unwinding reaction, allowing the helicase to function efficiently at low ATP concentrations.
Adenosine Triphosphatases↗
Deletion of chromosome 11p15, p12, q22, q23-24 loci in human prostate cancer.
Loss of heterozygosity (LOH) on chromosome 11 is frequently altered in various epithelial cancers. The present study was designed to investigate LOH on chromosome 11 in microdissected samples of normal prostatic epithelium and invasive carcinoma from the same patients. For this purpose, DNA was extracted from the microdissected normal and tumor cells of 38 prostate cancers, amplified by polymerase chain reaction PCR and analyzed for LOH on chromosome 11 using 9 different polymorphic DNA markers (D11S1307, D11S989, D11S1313, D11S898, D11S940, D11S1818, D11S924, D11S1336 and D11S912). LOH on chromosome 11 was identified in 30 of 38 cases (78%) with at least one marker. Four distinct regions of loss detected were: 1) at 11p15, at loci between D11S1307 and D11S989; 2) at 11p12, on locus D11S131 (11p12); 3) at 11q22, on loci D11S898, D11S940 and D11S1818; and 4) at 11q23-24, on loci between D11S1336 and D11S912. We found 25% of the tumors with LOH at 11p15; 39% had LOH at 11p12; 66% had LOH at 11q22; and 47% had LOH at 11q23-24. These deletions at 11p15, 11p12, 11q22 and 11q23-24 loci were not related to the stage or grade of the tumor.
Alleles↗
Synaptojanin inhibition of phospholipase D activity by hydrolysis of phosphatidylinositol 4,5-bisphosphate.
A 150-kDa protein that inhibits phospholipase D (PLD) activity stimulated by ADP-ribosylation factor and phosphatidylinositol 4, 5-bisphosphate (PI(4,5)P2) was previously purified from rat brain. The sequences of peptides derived from the purified PLD inhibitor now identify it as synaptojanin, a nerve terminal protein that has been implicated in the endocytosis of fused synaptic vesicles and shown to be a member of the inositol polyphosphate 5-phosphatase family. Further characterization of the enzymatic properties of synaptojanin now shows that it hydrolyzes only the 5-phosphate from inositol 1,4,5-trisphosphate (I(1,4,5)P3) and that it does not catalyze the dephosphorylation of either I(1,3,4)P3 or inositol 1, 4-bisphosphate. However, synaptojanin hydrolyzes both the 4- and 5-phosphates of PI(4,5)P2 and the 4-phosphate of phosphatidylinositol 4-phosphate, converting both compounds to phosphatidylinositol. Magnesium is required for the hydrolysis of I(1,4,5)P3, but not for that of phosphoinositides, by synaptojanin. The inhibition of PLD by synaptojanin is attributable to its ability to hydrolyze PI(4,5)P2. Synaptojanin did not inhibit PLD in the absence of PI(4,5)P2, and the extent of PLD inhibition was related to the extent of PI(4,5)P2 hydrolysis in substrate vesicles. It has been proposed that the biosynthesis of PI(4,5)P2 and the activation of PLD by ADP-ribosylation factor constitute a positive loop to increase rapidly the concentrations of PI(4,5)P2 and phosphatidic acid (PA) during membrane vesiculation. The PA thus produced, probably together with PI(4,5)P2, facilitates vesicle coat assembly. The hydrolysis of PI(4,5)P2, and consequent inhibition of PLD, by synaptojanin might therefore constitute a mechanism to halt the positive loop connecting PI(4,5)P2 and PA during the endocytotic cycle of synaptic vesicles and serve as a signal for uncoating.
Amino Acid Sequence↗