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Biomedical subjects

Paul C Kuo

Publications and source records attributed to Paul C Kuo.

At least 19 recordsLinked to original sources
PubMed2005

Half-life analysis of pancreas and kidney transplants.

Although graft and patient survival data are available for pancreas and kidney transplants, they are rarely reported in terms of half-life. Our aim was to determine whether a more relevant measure of outcome is patient and allograft half-life. Using the data from the Organ Procurement and Transplantation Network Registry on kidney and pancreas transplants from January 1988 to December 1996, patient and graft half-life and 95% confidence intervals were calculated and demographic variables compared. No significant differences were found between demographic variables. Kidneys transplanted in diabetics as a simultaneous kidney-pancreas (SPK) fared better than diabetics receiving a kidney alone (9.6 vs. 6.3 years). Pancreatic graft survival in an SPK pair was better than pancreas after kidney transplant or pancreas transplant alone (11.2 vs. 2.5 years). Because kidney and pancreatic grafts have a longer half-life when transplanted with their mate grafts, we should consider the relative benefits of SPKs over pancreas after kidney transplant or pancreas transplant alone to limit the loss of precious resources.

Adult↗
PubMed2005

Transcriptional regulatory functions of heterogeneous nuclear ribonucleoprotein-U and -A/B in endotoxin-mediated macrophage expression of osteopontin.

Osteopontin (OPN) is a highly hydrophilic and negatively charged sialoprotein of approximately 298 amino acids with diverse regulatory functions, including cell adhesion and migration, tumor growth and metastasis, atherosclerosis, aortic valve calcification, and repair of myocardial injury. OPN is unique as an endogenous negative feedback inhibitor of NO expression. However, the specific cis- and trans-regulatory elements that determine the extent of endotoxin (LPS)- and NO-mediated induction of OPN synthesis are unknown. We have previously shown that LPS-induced S-nitrosylation of heterogeneous nuclear ribonucleoprotein (hnRNP)-A/B inhibits its activity as a constitutive trans-repressor of the OPN transcription by significantly decreasing its DNA binding activity. hnRNPs were originally described as chromatin-associated RNA-binding proteins that form complexes with RNA polymerase II transcripts. The hnRNP family is comprised of >20 proteins that contribute to the complex around nascent pre-mRNA and are thus able to modulate RNA processing. In this subsequent study, again using RAW 264.7 murine macrophages and COS-1 cells, we demonstrate that hnRNP-A/B and hnRNP-U proteins serve antagonistic transcriptional regulatory functions for OPN expression in the setting of LPS-stimulated NO synthesis. In the presence of NO, hnRNP-A/B dissociates from its OPN promoter site with subsequent derepression of OPN promoter activity. Subsequently, hnRNP-U binds to the same site to further augment OPN promoter activation. This has not been previously described for the hnRNP proteins. Our results represent a unique transcriptional regulatory mechanism which involves interplay between members of the hnRNP protein family.

Animals↗
PubMed2005

Osteopontin silencing by small interfering RNA suppresses in vitro and in vivo CT26 murine colon adenocarcinoma metastasis.

Hepatic metastasis is a primary cause for failure of locoregional therapy in colorectal cancer. Increased expression of osteopontin (OPN), a ligand for alpha(v)beta3 integrin and CD44 receptors, is associated with metastasis in several types of cancer. However, the mechanism by which OPN mediates metastasis in colorectal cancer remains unknown. We hypothesized that OPN mediates invasion of colon cancer cells through basement membrane and migration through extracellular matrix (ECM). In this study, we used CT26 murine colon adenocarcinoma cells syngeneic to BALB/c mice to generate cell lines (pS-OPN) in which OPN expression was suppressed through small interfering RNA (siRNA) plasmids. CT26 wild-type cells (WT) and CT26 cells stably expressing murine-mismatch siRNA (pS-MM) served as controls. Western blotting quantified OPN protein levels and our most downregulated clone, pS-OPN-A4, demonstrated a mean 3.0-fold decrease in OPN protein expression versus WT. In vitro cell motility and invasiveness were decreased in pS-OPN-A4 by 3.6-fold (P = 0.004 versus WT) and 4.1-fold (P = 0.01 versus WT), but proliferation was similar amongst cell lines. We demonstrated that OPN suppression significantly correlates with MMP-2 downregulation. In vivo hepatic metastasis was assessed by quantifying liver weights and surface tumor nodules in 33 BALB/c mice (11/group) subjected to intrasplenic injection of tumor cells. pS-OPN-A4 resulted in a 50.4% decrease in mean liver weight compared with WT (3.79 +/- 1.49 g versus 1.88 +/- 1.34 g, P = 0.009). Only 18% of pS-OPN-A4 livers had >20 metastatic surface nodules compared with 89% for WT and 75% for pS-MM-V6. This study demonstrates that RNA interference stably reduces CT26 tumor expression of OPN and significantly attenuates CT26 colon cancer metastasis by diminishing tumor cell motility and invasiveness.

Adenocarcinoma↗
PubMed2005

Nitric oxide-dependent osteopontin expression induces metastatic behavior in HepG2 cells.

Our objective was to delineate the role of nitric oxide (NO) in osteopontin (OPN)-associated metastatic properties in HepG2 cells. OPN is the major phosphoprotein secreted by malignant cells in patients with advanced metastatic cancer, is frequently overexpressed in human tumors, and has been implicated as a key mediator of tumor cell metastasis. OPN is significantly overexpressed in hepatocellular cancer (HCC) and correlates with capsular infiltration and behavior. In addition, significantly increased inducible nitric oxide synthase (iNOS) and NO expression are found in HCC. In archived human samples of normal, cirrhotic, and HCC livers, we demonstrate that iNOS and OPN protein are strongly coexpressed in hepatoma cells. In the setting of cirrhosis, hepatocytes express iNOS, but not OPN. Further in vitro studies performed with HepG2 hepatocellular cancer cells demonstrate that exogenous NO transcriptionally upregulates OPN expression. Enhanced expression of OPN in this setting is associated with increased in vitro cell adhesion and invasion. These data suggest that NO enhances HCC expression of OPN and, as a result, conveys a metastatic phenotype.

Carcinoma, Hepatocellular↗
PubMed2005

Redox-mediated upregulation of hepatocyte iNOS transcription requires coactivator PC4.

BACKGROUND: Redox-mediated upregulation of transcription of hepatocyte inducible nitric oxide synthase (iNOS) requires hepatocyte nuclear factor IV-alpha (HNF-4alpha). In this setting, PC4 is often isolated with HNF-4alpha in DNA-protein pull-down studies. Transcriptional coactivator PC4 facilitates activator-dependent transcription via interactions with basal transcriptional machinery that are independent of PC4-DNA binding. We hypothesized that PC4 is a necessary component of HNF-4alpha-regulated redox-sensitive hepatocyte iNOS transcription. METHODS: Murine CCL9.1 hepatocytes were stimulated with interleukin-1beta (IL-1beta; 1000 U/mL) in the presence and absence of peroxide (H(2)O(2); 50 nmol/L). Antisense and sense oligonucleotides to HNF-4alpha and PC4 were added selectively. Coimmunoprecipitation (Co-IP) studies determined the association between HNF-4alpha and PC4. Transient transfection was performed with the use of a luciferase reporter construct containing the murine iNOS promoter (1.8 kb). Chromatin immunoprecipitation assays determined in vivo binding of PC4 and HNF-4alpha to the iNOS promoter region. RESULTS: Ablation of either HNF-4alpha or PC4 blunted the peroxide-mediated increase in the activation of the iNOS promoter. In IL-1beta+H(2)O(2) only, co-IP studies demonstrated the presence of an HNF-4alpha-PC4 protein complex, and chromatin immunoprecipitation assays demonstrated that this complex binds to the genomic iNOS promoter. CONCLUSIONS: Redox-mediated upregulation of hepatocyte iNOS transcription requires an HNF-4alpha-PC4 transcriptional complex.

Animals↗
PubMed2005

The current status of living donor liver transplantation.

In response to the critical organ shortage, transplant professionals have utilized living donors in an attempt to decrease the mortality rate associated with waiting on the liver transplant list. Although the surgical techniques were first utilized clinically 15 years ago, application of LDLT has been somewhat limited by the steep learning curve associated with developing a program. Clinical success with LDLT in children was realized early in the experience and application of the techniques to the adult population has occurred more recently. Although transplant centers embark on LDLT with enthusiasm, the safety of the donor must always be at the forefront of the process. Potential donors must come to the decision to donate without pressure from members of the family or transplant team. He/she should also be assigned advocates who constantly promote the donor's best interest. Failure to adhere to strict donor evaluation protocols and standardized operative techniques could result in disastrous consequences.

Chronic Disease↗
PubMed2005

Gastrointestinal hemorrhage due to complicated gastroduodenal ulcer disease in liver transplant patients taking sirolimus.

Sirolimus is emerging as a popular immunosuppressive agent for patients undergoing solid organ and pancreatic cell transplantation. Here, we report the clinical courses of three patients receiving sirolimus who developed aggressive gastroduodenal ulcer disease. One patient died from massive gastrointestinal bleeding, and ulcers in the other two patients healed only after discontinuation of sirolimus. We propose that the mechanism underlying this severe ulcer diathesis, and poor ulcer healing, was linked to the well-known inhibitory effects of sirolimus on wound healing. We propose that sirolimus should be used carefully (or even withheld) in patients with known or previous ulcer disease, and further that it should be used prudently and/or in conjunction with aggressive prophylaxis therapy in those at risk for ulcer disease.

Adult↗
PubMed2005

Acute kidney transplant failure following transurethral bladder polyp fulguration.

Ureteral obstruction and anastomotic leak represent the most common urologic complications of kidney transplantation. Delay in diagnosis or treatment can lead to allograft loss. Obstruction of the ureter occurs in 2% of kidney transplant recipients. Although the majority of cases are immediate technical complications of the operation, subsequent manipulation of the genitourinary system can result in iatrogenic ureteral injury. We report the case of a long-term kidney transplant recipient who developed obstructive uropathy and acute renal failure requiring dialysis after undergoing cystoscopy and bladder polyp fulguration. The etiology was inadvertent thermal injury of the ureteroneocystostomy incurred during the procedure. After attempted percutaneous management, definitive open repair resulted in a return of allograft function to baseline.

Acute Kidney Injury↗
PubMed2004

Identification of S-nitrosylated proteins in endotoxin-stimulated RAW264.7 murine macrophages.

Nitric oxide (NO) is an omnipresent regulator of cell function in a variety of physiologic and pathophysiologic states. In part, NO exerts its actions by S-nitrosylation of target thiols, primarily in cysteine residues. Delineating the functional correlates of S-nitrosylation can begin with identification of the entire population of S-nitrososylated proteins. Recently, the biotin switch technique was developed to allow a proteomic approach to identification of the "universe" of S-nitrsoylated proteins. In this study using endotoxin-stimulated RAW264.7 murine macrophages, we have utilized the biotin-switch technique and protein sequencing to identify S-nitrosylated proteins in this setting. In contrast to other studies utilizing exogenous sources of NO, our approach utilizes endogenous NO synthesis as the basis for S-nitrosylation. Our results indicate multiple unique proteins not previously identified as S-nitrosylation targets: enolase, pyruvate kinase, elongation factor-1 and -2, plastin-2, FRAG-6, CEM-16, and SMC-6. While the ubiquitous nature of NO argues for some degrees of commonality, S-nitrosylation of unique proteins specific to endotoxin stimulated macrophages suggests regulatory mechanisms for which NO is necessary, but not sufficient.

Amidines↗
PubMed2004

A transcriptional repressor of osteopontin expression in the 4T1 murine breast cancer cell line.

Osteopontin (OPN) is a highly hydrophilic and negatively charged sialoprotein of approximately 298 amino acids which is an important mediator of tumor metastatic behavior. We have previously demonstrated that endotoxin-dependent OPN gene transcription is regulated by a constitutive transcriptional repressor protein, heterogeneous nuclear ribonucleoprotein A/B (hnRNP-A/B). However, in the context of cancer, the role of hnRNP-A/B in the transcriptional regulation of OPN and its metastasis-promoting functions has not been previously studied. We examined hnRNP-A/B in the 4T1 murine mammary epithelial tumor cell line, a thioguanine resistant subline which closely mimics stage IV breast cancer in humans. Our data indicate that hnRNP-A/B p37 binds to the OPN promoter, significantly decreases OPN promoter activity and mRNA levels, ablates OPN protein expression, and inhibits OPN dependent in vitro correlates of metastatic behavior, motility, and invasion. These results are unique and may suggest new therapies to re-establish loco-regional control of cancers.

Animals↗
PubMed2004

Differential osteopontin expression in phenotypically distinct subclones of murine breast cancer cells mediates metastatic behavior.

Cancer progression depends on an accumulation of metastasis-supporting cell signaling molecules, which target signal transduction pathways and, ultimately, gene expression. One such molecule, osteopontin (OPN), represents a key molecular signaling event in tumor progression and metastasis. However, the transcriptional regulatory mechanisms that underlie OPN expression in the setting of breast cancer have not been well studied. In this regard, we have examined the differential transcriptional regulation of OPN in the murine mammary epithelial tumor cell lines, 4T1 and 4T07, which are sublines derived from the parental population of 410.4 cells from Balb/cfC3H mice. These lines are phenotypically heterogeneous in their metastatic behavior. 4T1 hematogenously metastasizes to the lung, liver, bone, and brain, whereas 4T07 is highly tumorigenic but fails to metastasize. The tumor growth and metastatic spread of 4T1 cells closely mimics stage IV breast cancer. We demonstrate that a Ras-independent, phosphoinositide-3 kinase-dependent, c-Jun N-terminal kinase-dependent phosphorylation of c-Jun results in binding of an AP-1 c-Jun homodimer to the OPN promoter in 4T1 cells. This differential up-regulation of OPN gene transcription and protein expression in 4T1 cells conveys in vitro correlates of a metastatic phenotype. These results provide new insight into the transcriptional regulation of OPN as a key mediator of metastatic behavior in malignancy.

Animals↗
PubMed2004

Osteopontin increases CD44 expression and cell adhesion in RAW 264.7 murine leukemia cells.

BACKGROUND: Osteopontin (OPN) is an inducible cell attachment protein which binds alphavbeta3-integrin and CD44 receptors to promote tumor metastasis. We hypothesized that OPN alters expression of its CD44 receptor to promote neoplastic cell migration. METHODS: RAW264.7 cells were stimulated with OPN (0-10 nM) for 0-12 hours to determine the time- and concentration-dependence of CD44 protein and mRNA expression. In selected instances, a competitive ligand for the alphavbeta3-integrin, GRGDSP (50 nM), or an inhibitor of protein synthesis, anisomycin (10 microg/ml), was added. Cell adhesion to hyaluronan was assayed with the crystal violet assay. RESULTS: OPN upregulates plasma membrane total CD44 protein in a concentration-(ANOVA P = 0.001) and time-dependent (ANOVA P = 0.001) fashion. CD44v6 is not altered. Cell adhesion to hyaluronate increases in parallel with CD44 expression. Steady state mRNA levels for CD44 are not altered by OPN. 5 nM OPN increases CD44 protein half-life from 105 +/- 11 minutes to 278 +/- 15 minutes. (P < 0.03) Blockade of either alphavbeta3-integrin ablates the OPN-dependent increase in CD44. CONCLUSIONS: These data indicate that OPN increases plasma membrane CD44 expression and cell adhesion by binding to its alphavbeta3-integrin receptor. We conclude that OPN may promote tumor metastatic behavior by CD44 expression.

Animals↗
PubMed2004

Peroxide-mediated chromatin remodelling of a nuclear factor kappa B site in the mouse inducible nitric oxide synthase promoter.

Hepatocyte expression of iNOS (inducible nitric oxide synthase) and synthesis of nitric oxide convey protective antioxidant functions in models of sepsis, shock and reperfusion. However, the underlying redox-sensitive mechanisms that regulate hepatocyte expression of iNOS and its antioxidant functions are largely unknown. Activity of the transcription factor NF-kappaB (nuclear factor kappaB) is known to be redox-modulated. In this regard, the mouse hepatocyte iNOS promoter has NF-kappaB-binding sites at nt -1044 to -1034 and at nt -114 to -104, which are considered to be critical for iNOS expression in response to pro-inflammatory cytokine stimulation. The relative contribution of these two NF-kappaB-binding sites in the mouse iNOS promoter to hepatocyte iNOS promoter activity in the context of oxidative stress has not been characterized previously. In addition, although the cis - and trans -regulatory factors controlling mouse hepatocyte iNOS expression have been well-characterized, the local changes in chromatin structure that accompany activation of iNOS gene transcription have not been considered. In the present study, we demonstrate that (1) in the absence of exogenous oxidative stress, the NF-kappaB site at nt -114 is inactive and (2) peroxide-mediated oxidative stress induces hyperacetylation and enhanced accessibility of the restriction enzyme to this NF-kappaB region. Our results suggest that chromatin structural changes activate this NF-kappaB site and increase interleukin-1beta-stimulated iNOS expression in the presence of oxidative stress.

Animals↗
PubMed2004

S-nitrosylation of heterogeneous nuclear ribonucleoprotein A/B regulates osteopontin transcription in endotoxin-stimulated murine macrophages.

Osteopontin (OPN) is a highly hydrophilic and negatively charged sialoprotein of approximately 298 amino acids that contains a Gly-Arg-Gly-Asp-Ser sequence. It is a secreted protein with diverse regulatory functions, including cell adhesion and migration, tumor growth and metastasis, atherosclerosis, aortic valve calcification, and repair of myocardial injury. Despite the many recognized functions of OPN, very little is known of the transcriptional regulation of OPN. In this regard, we have previously demonstrated that OPN transcription and promoter activity are significantly up-regulated in response to NO in a system of endotoxin-stimulated murine macrophages. However, the specific cis- and trans-regulatory elements that determine the extent of endotoxin- and NO-mediated induction of OPN synthesis are unknown. In this follow-up study, we demonstrate that: 1) OPN gene transcription is regulated by a constitutive transcriptional repressor protein, heterogeneous nuclear ribonucleoprotein A/B (hnRNP A/B); 2) inhibition of in vivo hnRNP DNA binding activity is accompanied by increased S-nitrosylation of hnRNP A/B in the setting of lipopolysaccharide (LPS)-mediated NO synthesis; 3) inhibition of LPS mediated NO synthesis restores hnRNP DNA binding and decreases the extent of S-nitrosylation; and 4) S-nitrosylation of hnRNP at cysteine 104 inhibits in vitro DNA binding activity, which is reversed by dithiothreitol. Our findings suggest that LPS induced S-nitrosylation of hnRNP inhibits its activity as a constitutive repressor of the OPN promoter and results in enhanced OPN expression.

Animals↗
PubMed2004

Determining benchmarks for evaluation and management coding in an academic division of general surgery.

BACKGROUND: Academic divisions of general surgery are facing ever-increasing financial pressures. Cost-cutting is a common approach to maintaining profitability, but strategies to increase revenue should not be ignored. One specific avenue for enhanced revenue generation in general surgery is that of coding for evaluation and management (E&M). Although this is the financial life-blood for many of the consultative services in departments of medicine, E&M coding is an often neglected and misunderstood component of surgical care. STUDY DESIGN: The financial records for the Division of General Surgery were reviewed for the period of January 2001 to June 2003. Specifically, charges and receipts for inpatient procedures and hospital visits (CPT codes 99231, 99232, and 99233) were determined. The analysis was limited to surgeons with a primary clinical focus based at the University hospital rather than the neighboring community or Veteran's Affairs hospitals. In addition, ICD-9 and All Patient Refined Diagnosis Related Groups (APR-DRG) data were analyzed to determine the surgeon-specific number of inpatients and inpatient-days with more than one ICD-9 code or secondary ICD-9 codes, or both, or an APR-DRG severity of illness score of 2, 3, or 4. These categories were defined to determine the number of inpatient-days for which E&M coding could be billed for management of secondary medical diagnoses. RESULTS: Analysis demonstrates that actual E&M charges were 40% to 47% of predicted minimums for E&M charges for the period under study. In theory, this result translates into an annual gain in receipts of 400,000 dollars to 600,000 dollars. CONCLUSIONS: We conclude that the ICD-9 and APR-DRG models may serve as benchmarks to determine the limits for E&M revenue stream, and E&M coding may represent an underutilized source of revenue among academic departments of surgery.

Academic Medical Centers↗
PubMed2004

The role of Osteopontin in tumor metastasis.

Osteopontin (OPN) is a glyco-phosphoprotein that is expressed and secreted by numerous human cancers. OPN functions in cell adhesion, chemotaxis, macrophage-directed interleukin-10 (IL-10) suppression, stress-dependent angiogenesis, prevention of apoptosis, and anchorage-independent growth of tumor cells by regulating cell-matrix interactions and cellular signaling through binding with integrin and CD44 receptors. While constitutive expression of OPN exists in several cell types, induced expression has been detected in T-lymphocytes, epidermal cells, bone cells, macrophages, and tumor cells in remodeling processes such as inflammation, ischemia-reperfusion, bone resorption, and tumor progression. Recently, substantial evidence has linked OPN with the regulation of metastatic spread by tumor cells. However, the molecular mechanisms that define the role of OPN in tumor metastasis are incompletely understood. Transcriptional regulators that contribute to the induction of OPN expression have received significant attention as potential modulators of the OPN-mediated metastatic phenotype. The following review will discuss the molecular structure of OPN, the evidence for its functional role in tumor cell metastasis, the downstream signals that activate invasive mechanisms, and the recent reports concerning regulation of OPN transcription.

Extracellular Matrix↗
PubMed2004

Intraoperative fluid management during orthotopic liver transplantation.

OBJECTIVE: To assess clinical safety of a low central venous pressure (CVP) fluid management strategy in patients undergoing liver transplantation. DESIGN: Retrospective record review comparing 2 transplant centers, one using the low CVP method and the other using the normal CVP method. SETTING: University-based, academic, tertiary care centers. PARTICIPANTS: Patients undergoing orthotopic cadaveric liver transplantation. INTERVENTIONS: Each center practiced according to its own standard of care. Center 1 maintained an intraoperative CVP <5 mmHg using fluid restriction, nitroglycerin, forced diuresis, and morphine. If pressors were required to maintain systolic arterial pressure >90 mmHg, phenylephrine or norepinephrine was used. At center 2, CVP was kept 7 to 10 mmHg and mean arterial pressure >75 mmHg with minimal use of vasoactive drugs. MEASUREMENTS AND MAIN RESULTS: Data collected included United Network for Organ Sharing status, surgical technique, intraoperative transfusion rate, preoperative and peak postoperative creatinine, time spent in intensive care unit and hospital, incidence of death, and postoperative need for hemodialysis. Principal findings include an increased rate of transfusion in the normal CVP group but increased rates of postoperative renal failure (elevated creatinine and more frequent need for dialysis) and 30-day mortality in the low CVP group. CONCLUSIONS: Despite success in lowering blood transfusion requirements in liver resection patients, a low CVP should be avoided in patients undergoing liver transplantation.

Adrenergic alpha-Agonists↗