Biomedical subjects

J D Pearson

Publications and source records attributed to J D Pearson.

At least 19 recordsLinked to original sources

PubMed2001

Modulation of adenosine transport by insulin in human umbilical artery smooth muscle cells from normal or gestational diabetic pregnancies.

1. Adenosine transport was measured in human cultured umbilical artery smooth muscle cells, isolated from non-diabetic or gestational diabetic pregnancies, under basal conditions and after pretreatment in vitro with insulin. 2. Adenosine transport in non-diabetic smooth muscle cells was significantly increased by insulin (half-maximal stimulation at 0.33 +/- 0.02 nM, 8 h) and characterized by a higher maximal rate (V(max)) for nitrobenzylthioinosine (NBMPR)-sensitive (es) saturable nucleoside transport (17 +/- 5 vs. 52 +/- 12 pmol (microg protein)(-1) min(-1), control vs. insulin, respectively) and maximal binding sites (B(max)) for [(3)H]NBMPR (0.66 +/- 0.07 vs. 1.1 +/- 0.1 fmol (microg protein)(-1), control vs. insulin, respectively), with no significant changes in Michaelis-Menten (K(m)) and dissociation (K(d)) constants. 3. In contrast, in smooth muscle cells from diabetic pregnancies, where the values of V(max) for adenosine transport (59 +/- 4 pmol (microg protein)(-1) min(-1)) and B(max) for [(3)H]NBMPR binding (1.62 +/- 0.16 fmol (microg protein)(-1)) were significantly elevated by comparison with non-diabetic cells, insulin treatment (1 nM, 8 h) reduced the V(max) for adenosine transport and B(max) for [(3)H]NBMPR binding to levels detected in non-diabetic cells. 4. In non-diabetic cells, the stimulatory effect of insulin on adenosine transport was mimicked by dibutyryl cGMP (100 nM) and reduced by inhibitors of phosphatidylinositol 3-kinase (10 nM wortmannin), nitric oxide synthase (100 microM N (G)-nitro-L-arginine methyl ester, L-NAME) or protein synthesis (1 microM cycloheximide), whereas inhibition of adenylyl cyclase (100 microM SQ-22536) had no effect. 5. Wortmannin or SQ-22536, but not L-NAME or cycloheximide, attenuated the inhibitory action of insulin on the diabetes-induced stimulation of adenosine transport. 6. Protein levels of inducible NO synthase (iNOS) were similar in non-diabetic and diabetic cells, but were increased by insulin (1 nM, 8 h) only in non-diabetic smooth muscle cells. 7. Our results suggest that adenosine transport via the es nucleoside transporter is modulated differentially by insulin in either cell type. Insulin increased adenosine transport in non-diabetic cells via NO and cGMP, but inhibited the diabetes-elevated adenosine transport via activation of adenylyl cyclase, suggesting that the biological actions of adenosine may be altered under conditions of sustained hyperglycaemia in uncontrolled diabetes.

Adenosine↗

PubMed2001

A reference map of human lung MRC-5 fibroblast proteins using immobilized pH gradient-isoelectric focusing-based two-dimensional electrophoresis.

We report the first protein map of human adult lung MRC-5 fibroblasts using isoelectric focusing-immobilized pH gradient-based two-dimensional polyacrylamide gel electrophoresis. MRC-5 is an immortalised cell line used in a wide range of investigations. The two-dimensional gel pattern of proteins generated from any given cell system provides a fingerprint that is unique to those cells. Therefore, the establishment of a protein map for a particular cell system provides a useful reference tool as a "master map" for subsequent studies using those cells. In this map a total of 98 protein spots were identified by comparative searches of the nucleotide and protein database using peptide masses obtained by matrix-assisted laser desorption/ionization time of flight following trypsin digestion. To increase the utility of the reference map, cells were cultured in both Dulbecco's modified Eagle medium (DMEM), the standard medium, and Roswell Park Memorial Institute (RPMI)-1640. Two-dimensional gel protein patterns of MRC-5 cultures were shown to be largely unaffected by the use of RPMI compared to DMEM, respectively. In combination with the reference map, the standardised protocol described provides a tool for comparative studies involving MRC-5 cells in which nonspecific variation is minimized.

Adult↗

PubMed2001

Contemporary update of prostate cancer staging nomograms (Partin Tables) for the new millennium.

OBJECTIVES: We previously presented nomograms combining preoperative serum prostate-specific antigen (PSA), clinical (TNM) stage, and biopsy Gleason score to provide the likelihood of various final pathologic stages at radical retropubic prostatectomy. The data for the original nomograms were collected from men treated between 1982 and 1996. During the past 10 years, the stage at presentation has shifted, with more men presenting with Stage T1c, Gleason score 5 to 6, and serum PSA levels less than 10.0 ng/mL. In this work, we update the "Partin Tables" with a more contemporary cohort of men treated since 1994 and with revised PSA and Gleason categories. METHODS: Multinomial log-linear regression analysis was used to estimate the likelihood of organ-confined disease, extraprostatic extension, seminal vesicle or lymph nodal status from the preoperative PSA stratified as 0 to 2.5, 2.6 to 4.0, 4.1 to 6.0, 6.1 to 10.0, and greater than 10 ng/mL, clinical (AJCC-TNM, 1992) stage (T1c, T2a, T2b, or T2c), and biopsy Gleason score stratified as 2 to 4, 5 to 6, 3 + 4 = 7, 4 + 3 = 7, or 8 to 10 among 5079 men treated with prostatectomy (without neoadjuvant therapy) between 1994 and 2000 at Johns Hopkins Hospital. The average age was 58 years. RESULTS: In this cohort, more than 60% had T1c, more than 75% had Gleason score of 6, more than 70% had PSA greater than 2.5 and less than 10.0 ng/mL, and more than 60% had organ-confined disease. Nomograms of the robust estimated likelihoods and 95% confidence intervals were developed from 1000 bootstrap analyses. The probability of organ-confined disease improved across the groups, and further stratification of the Gleason score and PSA level allowed better differentiation of individual patients. CONCLUSIONS: These updated "Partin Tables" were generated to reflect the trends in presentation and pathologic stage for men newly diagnosed with clinically localized prostate cancer at our institution. Clinicians can use these nomograms to counsel individual patients and help them make important decisions regarding their disease.

Adult↗

PubMed2001

Impaired response to interferon-gamma in activated macrophages due to tyrosine nitration of STAT1 by endogenous nitric oxide.

1. Inducible NO synthase (iNOS) expression and activity were measured in the mouse macrophage cell line J774 after exposure to bacterial lipopolysaccharide (LPS) with or without interferon-gamma (IFN-gamma). 2. Inhibition of NOS activity by concomitant N(G)-monomethyl-L-arginine (L-NMMA) treatment further increased iNOS protein levels, with a substantial increase in iNOS half-life. 3. Western blotting and ELISA demonstrated that several cell proteins were tyrosine-nitrated when iNOS activity was high. 4. Rapid IFN-gamma-induced phosphorylation of STAT1 was reduced by about 40% when cells were pretreated to induce iNOS, unless L-NMMA was present during the pretreatment period. 2D gel electrophoresis demonstrated the presence of nitrotyrosine in STAT1 after iNOS induction, and confirmed the reduction in phospho-STAT1 on subsequent stimulation with IFN-gamma for 15 min and its partial restoration when L-NMMA was present during the pretreatment period. 5. We did not detect tyrosine nitration of the upstream kinase JAK2 in LPS+IFN-gamma pretreated cells, but JAK2 activity was also impaired, and was partially restored by concomitant L-NMMA pretreatment. 6. We conclude that endogenous production of NO induces feedback inhibition of signalling pathways activated by IFN-gamma, at least in part by nitrating tyrosine residues in STAT1 which prevents phosphorylation.

Animals↗

PubMed2001

Fibroblast matrix gene expression and connective tissue remodeling: role of endothelin-1.

This study examines endothelin-induced modulation of extracellular matrix synthesis and remodeling by fibroblasts, and its potential role in the pathogenesis of systemic sclerosis (scleroderma). Endothelin-1 promoted fibroblast synthesis of collagen types I and III, but not fibronectin, by a mechanism dependent upon both ETA and ETB receptors. Conversely, endothelin-1 inhibited both protein expression of matrix metalloproteinase 1 and zymographic activity exclusively via ETA receptors. A dual regulatory role for endothelin-1 in transcriptional regulation was suggested by the ability of endothelin-1 to enhance steady-state levels of collagen mRNA and activate the proalpha2(I) collagen (Col1a2) promoter, but in contrast to reduce matrix metalloproteinase 1 transcript expression and suppress transcription of a human matrix metalloproteinase 1 promoter reporter construct in transient transfection assays. Although endothelin-1 significantly enhanced remodeling of three-dimensional collagen lattices populated by normal fibroblasts, this was not observed for lattices populated by systemic sclerosis fibroblasts. Promotion of matrix remodeling was dependent upon ETA receptor expression and was blocked by specific inhibitors of tyrosine kinases or protein kinase C. Reverse transcriptase polymerase chain reaction, S1 nuclease, and functional cell surface binding studies showed that normal and systemic sclerosis fibroblasts express both ETA and ETB receptors (predominantly ETA), but that ETA receptor mRNA levels and ETA binding sites on fibroblasts cultured from systemic sclerosis skin biopsies are reduced by almost 50%. Endothelin-1 is thus able to induce a fibrogenic phenotype in normal fibroblasts that is similar to that of lesional systemic sclerosis fibroblasts. Moreover, reduced responsiveness to exogenous endothelin-1 in systemic sclerosis suggests that downstream pathways may have already been activated in vivo. These data further implicate dysregulated endothelin-receptor pathways in fibroblasts in the pathogenesis of connective tissue fibrosis.

Cells, Cultured↗

PubMed2001

Vasoactive mediator release by fetal endothelial cells in intrauterine growth restriction and preeclampsia.

OBJECTIVE: Preeclampsia and fetal growth restriction are associated with poor placental perfusion, which may be accompanied by a compensatory release of vasoactive substances in the fetoplacental circuit. This study examines the effects of preeclampsia and fetal growth restriction on nitric oxide and prostacyclin signaling pathways in fetal endothelial cells. STUDY DESIGN: Human umbilical vein endothelial cells from 30 control pregnancies, 18 pregnancies with preeclampsia, and 9 pregnancies with intrauterine growth restriction were cultured. Intracellular cyclic guanosine monophosphate accumulation and 6-keto-prostaglandin F1alpha production were determined. RESULTS: Intracellular accumulation of cyclic guanosine monophosphate was significantly higher in the preeclampsia group and lower in the growth restriction group than in the control group (9.8, 1.8, and 3.9 pmol/microg protein for 5 minutes, respectively), whereas 6-keto-prostaglandin F1alpha production was not significantly different in the 3 groups. CONCLUSION: The data suggest that the fetoplacental vascular response to preeclampsia is to increase production of cyclic guanosine monophosphate, perhaps to maintain vessel dilatation and maximum flow through placental villi. In fetal growth restriction the umbilical vein endothelial cells do not or cannot respond to chronic hypoxia by increasing cyclic guanosine monophosphate, which may lead to fetoplacental vasoconstriction.

6-Ketoprostaglandin F1 alpha↗

PubMed2001

Single ribosomal protein mutations in antibiotic-resistant bacteria analyzed by mass spectrometry.

Mutations in several ribosomal proteins are known to be related to antibiotic resistance. For several strains of Escherichia coli, the mutated protein is known but the amino acid actually altered has not been documented. Characterization of these determinants for antibiotic resistance in proteins will further the understanding of the precise mechanism of the antibiotic action as well as provide markers for resistance. Mass spectrometry can be used as a valuable tool to rapidly locate and characterize mutant proteins by using a small amount of material. We have used electrospray and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry to map out all 56 ribosomal proteins in E. coli based on intact molecular masses. We used this fingerprinting approach to locate variants of ribosomal proteins displaying a change in mass. In particular we have studied proteins responsible for streptomycin, erythromycin, and spectinomycin resistance in three strains of E. coli, and then we characterized each mutation responsible for resistance by analyzing tryptic peptides of these proteins by using MALDI-TOF and nanoelectrospray tandem mass spectrometry. The results provided markers for antibiotic resistance and demonstrated that mass spectrometry can be used to rapidly investigate changes in individual proteins from a complex with picomole amounts of protein.

Amino Acid Sequence↗

PubMed2001

Agonist-specific cross talk between ERKs and p38(mapk) regulates PGI(2) synthesis in endothelium.

We have examined the mechanisms regulating prostacyclin (PGI(2)) synthesis after acute exposure of human umbilical vein endothelial cells (HUVEC) to interleukin-1 alpha (IL-1 alpha). IL-1 alpha evoked an early (30 min) release of PGI(2) and [(3)H]arachidonate that was blocked by the cytosolic phospholipase A(2)alpha (cPLA(2)alpha) inhibitor arachidonyl trifluoromethyl ketone. IL-1 alpha-mediated activation of extracellular signal-regulated kinase 1/2 (ERK1/2; p42/p44(mapk)) coincided temporally with phosphorylation of cPLA(2)alpha and with the onset of PGI(2) synthesis. The mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitors, PD-98059 and U-0126, blocked IL-1 alpha-induced ERK activation and partially attenuated cPLA(2)alpha phosphorylation and PGI(2) release, suggesting that ERK-dependent and -independent pathways regulate cPLA(2)alpha phosphorylation. SB-203580 treatment enhanced IL-1 alpha-induced MEK, p42/44(mapk), and cPLA(2)alpha phosphorylation but reduced thrombin-stimulated MEK and p42/44(mapk) activation. IL-1 alpha, but not thrombin, activated Raf-1 as assessed by immune-complex kinase assay, as did SB-203580 alone. These results show that IL-1 alpha causes an acute upregulation of PGI(2) generation in HUVEC, establish a role for the MEK/ERK/cPLA(2)alpha pathway in this early release, and provide evidence for an agonist-specific cross talk between p38(mapk) and p42/44(mapk) that may reflect receptor-specific differences in the signaling elements proximal to MAPK activation.

Arachidonic Acid↗

PubMed2001

Cross-linking of brain endothelial intercellular adhesion molecule (ICAM)-1 induces association of ICAM-1 with detergent-insoluble cytoskeletal fraction.

Intercellular adhesion molecule (ICAM)-1 plays a vital role in the process of leukocyte transmigration through endothelial cell (EC) barriers and has been shown to mediate signal transduction events in ECs induced either by its cross-linking or by the binding of T lymphocytes. Immunoblotting of ICAM-1 of Triton X-100 detergent fractions demonstrated that the majority of ICAM-1 was contained within the detergent-soluble fraction (noncytoskeletal associated) under basal conditions. After cross-linking of endothelial ICAM-1 with monoclonal antibody or coculture with T lymphocytes, EC ICAM-1 was observed to partition with a Triton X-100-insoluble (cytoskeletal associated) fraction in a dose- and time-dependent manner. Redistribution of ICAM-1 was specific, inasmuch as no association with the Triton X-100-insoluble fraction was observed after cross-linking of vascular cell adhesion molecule-1, nor did cross-linking of ICAM-1 result in a redistribution of the platelet and EC adhesion molecule. ICAM-1 association with the endothelial cytoskeleton after cross-linking was unaffected after treatment of the cells with cytochalasin D, C3-transferase, removal of extracellular calcium ions, or chelation of intracellular calcium ions. These data show that ICAM-1 colocalizes with the endothelial cytoskeleton and associates with a detergent-insoluble fraction after cross-linking.

Actins↗

PubMed2000

Regulation of adenosine transport by D-glucose in human fetal endothelial cells: involvement of nitric oxide, protein kinase C and mitogen-activated protein kinase.

The effects of elevated D-glucose on adenosine transport were investigated in human cultured umbilical vein endothelial cells isolated from normal pregnancies. Elevated D-glucose resulted in a time- (8-12 h) and concentration-dependent (half-maximal at 10+/-2 mM) inhibition of adenosine transport, which was associated with a reduction in the Vmax for nitrobenzylthioinosine (NBMPR)-sensitive (es) saturable nucleoside with no significant change in Km. d-Fructose (25 mM), 2-deoxy-D-glucose (25 mM) or D-mannitol (20 mM) had no effect on adenosine transport. Adenosine transport was inhibited following incubation of cells with the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA; 100 nM, 30 min to 24 h). D-Glucose-induced inhibition of transport was abolished by calphostin C (100 nM, an inhibitor of PKC), and was not further reduced by PMA. Increased PKC activity in the membrane (particulate) fraction of endothelial cells exposed to D-glucose or PMA was blocked by calphostin C but was unaffected by NG-nitro-L-arginine methyl ester (L-NAME; 100 microM, an inhibitor of nitric oxide synthase (NOS)) or PD-98059 (10 microM, an inhibitor of mitogen-activated protein kinase kinase 1). D-Glucose and PMA increased endothelial NOS (eNOS) activity, which was prevented by calphostin C or omission of extracellular Ca2+ and unaffected by PD-98059. Adenosine transport was inhibited by S-nitroso-N-acetyl-l, d-penicillamine (SNAP; 100 microM, an NO donor) but was increased in cells incubated with L-NAME. The effect of SNAP on adenosine transport was abolished by PD-98059. Phosphorylation of mitogen-activated protein kinases p44mapk (ERK1) and p42mapk (ERK2) was increased in endothelial cells exposed to elevated D-glucose (25 mM for 30 min to 24 h) and the NO donor SNAP (100 microM, 30 min). The effect of D-glucose was blocked by PD-98059 or L-NAME, which also prevented the inhibition of adenosine transport mediated by elevated D-glucose. Our findings provide evidence that D-glucose inhibits adenosine transport in human fetal endothelial cells by a mechanism that involves activation of PKC, leading to increased NO levels and p42-p44mapk phosphorylation. Thus, the biological actions of adenosine appear to be altered under conditions of sustained hyperglycaemia.

Adenosine↗

PubMed2000

Comparative efficiency of prostate-specific antigen screening strategies for prostate cancer detection.

CONTEXT: Despite widespread use of serum prostate-specific antigen (PSA) testing to detect prostate cancer, the relative effectiveness of different PSA screening strategies is unknown. OBJECTIVE: To compare prostate cancer mortality, PSA testing rates, and biopsy rates using various PSA screening strategies, including the standard strategy of annually testing men aged 50 through 75 years. DESIGN AND SETTING: A Monte-Carlo simulation based on a Markov model was used to simulate the natural history of prostate cancer using different starting ages, testing intervals, and PSA thresholds for prostate biopsy. Age-specific PSA levels and prostate biopsy detection probabilities were determined from population data and surgical series. MAIN OUTCOME MEASURES: Numbers of prevented prostate cancer deaths, PSA tests, and prostate biopsies per 1000 men aged 40 through 80 years, compared among 7 different strategies vs no screening. RESULTS: Compared with annual PSA testing beginning at age 50 years, the strategy of PSA testing at ages 40 and 45 years followed by biennial testing beginning at age 50 years was estimated to simultaneously reduce prostate cancer mortality and number of PSA tests and biopsies performed per 1000 men. Specifically, compared with no screening, the standard strategy prevents 3.2 deaths, with an additional 10,500 PSA tests and 600 prostate biopsies, while the earlier but less frequent strategy prevents 3.3 deaths, with an additional 7500 PSA tests and 450 prostate biopsies. Strategies that lowered the PSA threshold for prostate biopsy to below 4.0 ng/mL or strategies that used age-specific PSA levels were not more efficient than use of a PSA threshold of 4.0 ng/mL. These 2 findings remained true under all sensitivity analyses performed to test assumptions of the model. CONCLUSION: Recognizing that the efficacy of PSA screening is unproved, the standard strategy of annual PSA screening beginning at age 50 years appears to be less effective and more resource intensive compared with a strategy that begins earlier but screens biennially instead of annually. JAMA. 2000;284:1399-1405.

Adult↗

PubMed2000

Identification of candidate endothelial cell autoantigens in systemic lupus erythematosus using a molecular cloning strategy: a role for ribosomal P protein P0 as an endothelial cell autoantigen.

OBJECTIVE: To attempt to characterize the diversity and nature of antigens recognized by anti-endothelial cell antibodies (AECA) in patients with systemic lupus erythematosus (SLE) using a molecular cloning strategy. METHODS: AECA in sera of 15 SLE patients were measured by ELISA and Western blot analysis was used to examine the diversity of autoantigen targets in two clinically active patients. A human umbilical vein endothelial cell cDNA expression library was immunoscreened with sera from these two patients to identify their autoantigen targets. An anti-ribosomal P peptide antibody ELISA was used to assess the clinical significance of anti-ribosomal P protein antibodies in the sera of one patient. RESULTS: Significantly higher AECA levels were found in five patients with active disease and nephritis than in five patients with clinically inactive disease. Sera from two clinically active patients were found to recognize distinct spectra of autoantigens. The candidate autoantigens that were identified included (1) endothelial cell-specific plasminogen activator inhibitor; (2) the classical lupus antigen, i.e. ribosomal P protein P0; and (3) proteins never before described as putative autoantigens in SLE, including ribosomal protein L6, elongation factor 1alpha, adenyl cyclase-associated protein, DNA replication licensing factor, profilin II and the novel proteins HEAPLA 1 and HEAPLA 2 (human endothelial associated putative lupus autoantigens 1 and 2). In one patient, antibodies against ribosomal P protein P0 were predominant and levels of these antibodies correlated with total AECA levels, anti-DNA antibody titres, overall clinical score and renal disease in a longitudinal study. CONCLUSIONS: A panel of candidate endothelial autoantigens in SLE, which includes previously described autoantigens and novel targets, has been identified by a molecular cloning strategy. This novel molecular approach could also be applied to the identification of autoantigens in other autoimmune vascular diseases.

Autoantibodies↗

PubMed2000

Soluble thrombomodulin concentration is raised in scleroderma associated pulmonary hypertension.

OBJECTIVE: To investigate the expression of thrombomodulin in scleroderma associated pulmonary hypertension. METHODS: Soluble thrombomodulin (sTM), was measured in plasma samples from 34 scleroderma patients shown to have pulmonary hypertension at echocardiogram, and comparison drawn against samples from 38 scleroderma control patients, and 20 healthy controls. Serial measurements of sTM were performed in the 34 patients with scleroderma associated pulmonary hypertension to investigate possible changes in sTM concentration with progression of the condition. RESULTS: Mean sTM was raised in scleroderma associated pulmonary hypertension when compared with scleroderma controls (mean sTM 65.4 ng/ml v 43.3 ng/ml, p<0.05), and when compared with healthy controls (mean sTM 38.1 ng/ml, p<0.05). There was no significant difference between mean sTM in scleroderma controls and healthy controls. Mean sTM concentration did not change with progression of pulmonary hypertension. CONCLUSION: Plasma sTM is raised in scleroderma associated pulmonary hypertension. The pathogenesis of scleroderma associated pulmonary hypertension may be distinct from the pathogenesis of other forms of pulmonary vascular disease.

Adult↗

PubMed2000

Normal endothelial cell function.

Endothelial cell functions, primarily involving regulated mediator secretion or altered surface protein expression, are vital for normal homeostasis. Endothelial cells secrete the potent vasodilator and anti-platelet agent prostacyclin and nitric oxide, and also the potent vasoconstrictor peptide endothelin-1; they control the selective adhesion and emigration of leukocytes from the bloodstream; and they are the source of circulating von Willebrand factor, tissue plasminogen activator and type 1 plasminogen activator inhibitor. The properties of healthy endothelium ensure that an antithrombotic and anticoagulant balance is maintained in the bloodstream, and provide a tonic vasodilator action that controls blood flow and pressure on a minute-to-minute basis. Disturbances of normal endothelial function are strongly implicated in the pathogenesis of atherosclerosis and autoimmune vasculitic diseases including lupus.

Arteriosclerosis↗

PubMed2000

Validation of Partin tables for predicting pathological stage of clinically localized prostate cancer.

PURPOSE: The accurate prediction of pathological stage of prostate cancer using preoperative factors is a critical aspect of treatment. In 1997 Partin et al published tables predicting pathological stage using clinical stage, Gleason score and prostate specific antigen (PSA). We tested the validity of the Partin tables. MATERIALS AND METHODS: From 1990 to 1996 inclusively 5,780 patients underwent bilateral pelvic lymphadenectomy and radical prostatectomy for prostate cancer at the Mayo Clinic. However, only 2,475 of these patients met all inclusion criteria of no preoperative treatment, known biopsy Gleason score, available preoperative PSA done either before biopsy or more than 28 days after biopsy and clinical stage T1, T2 or T3a. Among the 2,475 patients 15 had positive lymph nodes and planned prostatectomy was abandoned. The receiver operating characteristics (ROC) curve area, observed and predicted Partin rates of each pathological stage, and positive and negative predictive values were used to compare the Mayo study to the Partin tables. RESULTS: The distribution of pathological stage was organ confined in 67% of Mayo cases versus 48% in the Partin study, extracapsular without seminal vesicle or node involvement in 18% versus 40%, seminal vesicle involvement without nodes in 9% versus 7% and were positive nodes in 6% versus 5%. Using the predicted probabilities of Partin et al the ROC curve area for predicted node positive disease was 0.84 for Mayo cases compared to an estimated 0. 82 in the Partin series. The ROC curve area for predicting organ confined cancer was 0.76 for the Mayo Clinic compared to an estimated 0.73 for the Partin series. The observed rates of node positive disease were similar to those predicted (Partin) based on clinical stage, PSA and Gleason score. For organ confined disease Mayo rates were consistently higher than those predicted from the Partin series using a cut point of 0.50 or greater. Positive and negative predictive values were 0.83 and 0.49 versus 0.63 and 0.70 for the Mayo Clinic and Partin series. CONCLUSIONS: Our study provides strong evidence that sensitivity and specificity of the Partin tables for external clinical sites are similar to what was reported.

Humans↗

PubMed1999

Transmembrane signalling mechanisms regulating expression of cationic amino acid transporters and inducible nitric oxide synthase in rat vascular smooth muscle cells.

The signalling mechanisms involved in the induction of nitric oxide synthase and l-arginine transport were investigated in bacterial lipopolysaccharide (LPS)- and interferon-gamma (IFN-gamma)-stimulated rat cultured aortic smooth muscle cells (RASMCs). The expression profile of transcripts for cationic amino acid transporters (CATs) and their regulation by LPS and IFN-gamma were also examined. Control RASMCs expressed mRNA for CAT-1, CAT-2A and CAT-2B. Levels of all three transcripts were significantly elevated in activated cells. Stimulated CAT mRNA expression and l-arginine transport occurred independently of protein kinase C (PKC), protein tyrosine kinase (PTK) and p44/42 mitogen-activated kinases (MAPKs), but were inhibited by the p38 MAPK inhibitor SB203580, which at 3 microM caused maximum inhibition of both responses. Induction of NO synthesis was independent of p44/42 MAPK activation and only marginally dependent on PKC, but was attenuated markedly by the PTK inhibitors genistein and herbimycin A. SB203580 differentially regulated inducible NO synthase expression and NO production, potentiating both processes at low micromolar concentrations and inhibiting at concentrations of >/=1 microM. In conclusion, our results suggest that RASMCs constitutively express transcripts for CAT-1, CAT-2A and CAT-2B, and that expression of these transcripts is significantly enhanced by LPS and IFN-gamma. Moreover, stimulation of l-arginine transport and induction of NO synthesis by LPS and IFN-gamma appear to be under critical regulation by the p38 MAPK, since both processes were significantly modified by SB203580 at concentrations so far shown to have no effect on other signalling pathways. Thus, in RASMCs, the p38 MAPK cascade represents an important signalling mechanism, regulating both enhanced l-arginine transport and induced NO synthesis.

Amino Acid Transport Systems, Basic↗

PubMed1999

Prostate-specific antigen testing of older men.

BACKGROUND: Elevated serum prostate-specific antigen (PSA) levels are predictive of a future diagnosis of prostate cancer. To test the hypothesis that older men with low PSA levels may require less intensive PSA testing because of a reduced prostate cancer detection rate, we evaluated the association between age, baseline PSA level, and prostate cancer detection. METHODS: We conducted a prospective cohort study among participants in a study of aging who had serial PSA measurements taken from age 60 or 65 years until they either were diagnosed with prostate cancer (cancer case subjects) or reached the age of 75 years (subjects without prostate cancer). The time of cancer detection among cancer case subjects was defined as the measurement date on which a PSA level above 4.0 ng/mL was detected (i.e., PSA conversion). Cancer case subjects and subjects without prostate cancer were analyzed according to baseline PSA level and age. RESULTS: All cancer case subjects in the 60-year-old cohort had baseline PSA levels above 0.5 ng/mL, and 14 of 15 cancer cases that would have been detected by a PSA conversion among the 65-year-old cohort were associated with baseline PSA levels of 1.1 ng/mL or more. If PSA testing were discontinued in men aged 65 years with PSA levels of 0.5 ng/mL or less, 100% (95% confidence interval [CI] = 78%-100%) of the cancers would still be detected by age 75 years; if PSA testing were discontinued in men aged 65 years who had PSA levels of 1.0 ng/mL or less, 94% (95% CI = 70%-100%) of the cancers would still be detected by age 75 years. CONCLUSIONS: These data suggest that a decrease in the intensity of screening among older men with low PSA values may not lead to an increase in undetected prostate cancer.

Age Factors↗

PubMed1999

Natural history of progression after PSA elevation following radical prostatectomy.

CONTEXT: In men who develop an elevated serum prostate-specific antigen level (PSA) after having undergone a radical prostatectomy, the natural history of progression to distant metastases and death due to prostate cancer is unknown. OBJECTIVE: To characterize the time course of disease progression in men with biochemical recurrence after radical prostatectomy. DESIGN: A retrospective review of a large surgical series with median (SD) follow-up of 5.3 (3.7) years (range, 0.5-15 years) between April 1982 and April 1997. SETTING: An urban academic tertiary referral institution. PATIENTS: A total of 1997 men undergoing radical prostatectomy, by a single surgeon, for clinically localized prostate cancer. None received neoadjuvant therapy, and none had received adjuvant hormonal therapy prior to documented distant metastases. MAIN OUTCOME MEASURES: After surgery, men were followed up with PSA assays and digital rectal examinations every 3 months for the first year, semiannually for the second year, and annually thereafter. A detectable serum PSA level of at least 0.2 ng/mL was evidence of biochemical recurrence. Distant metastases were diagnosed by radionuclide bone scan, chest radiograph, or other body imaging, which was performed at the time of biochemical recurrence and annually thereafter. RESULTS: The actuarial metastasis-free survival for all 1997 men was 82% (95% confidence interval, 76%-88%) at 15 years after surgery. Of the 1997 men, 315 (15%) developed biochemical PSA level elevation. Eleven of these underwent early hormone therapy after the recurrence and are not included in the study. Of the remaining 304 men, 103 (34%) developed metastatic disease within the study period. The median actuarial time to metastases was 8 years from the time of PSA level elevation. In survival analysis, time to biochemical progression (P<.001), Gleason score (P<.001), and PSA doubling time (P<.001) were predictive of the probability and time to the development of metastatic disease. An algorithm combining these parameters was constructed to stratify men into risk groups. Once men developed metastatic disease, the median actuarial time to death was 5 years. The time interval from surgery to the appearance of metastatic disease was predictive of time until death (P<.02). CONCLUSIONS: Several clinical parameters help predict the outcomes of men with PSA elevation after radical prostatectomy. These data may be useful in the design of clinical trials, the identification of men for enrollment into experimental protocols, and counseling men regarding the timing of administration of adjuvant therapies.

Disease Progression↗