Paul C. Kuo

Osteopontin: regulation in tumor metastasis

Osteopontin is a secreted phosphoprotein that has been implicated as an important mediator of tumor metastasis and has been investigated for use as a biomarker for advanced disease and as a potential therapeutic target in the regulation of cancer metastasis. The OPN DNA sequence is highly conserved and the protein contains several important functional domains including αvβ integrin and CD44 binding sites. High levels of OPN expression correlate with tumor invasion, progression or metastasis in multiple cancer. Studies demonstrate that osteopontin mediates the molecular mechanisms which determine metastatic spread, such as prevention of apoptosis, extracellular matrix proteolysis and remodeling, cell migration, evasion of host-immune cells and neovascularization. Transcriptional regulation of OPN is complex and involves multiple pathways, including AP-1, Myc, v-Src, Runx/CBF, TGF-B/BMPs/Smad/Hox, and Wnt/ß–catenin/APC/GSK–3ß/Tcf-4. The current state of knowledge of OPN biology suggests that it is an attractive target for therapeutic modulation of metastatic disease.

Predictive Indices of Morbidity and Mortality After Liver Resection

Objective:To determine if use of Model for End-Stage Liver Disease (MELD) scores to elective resections accurately predicts short-term morbidity or mortality. Summary Background Data:MELD scores have been validated in the setting of end-stage liver disease for patients awaiting transplantation or undergoing transvenous intrahepatic portosystemic shunt procedures. Its use in predicting outcomes after elective hepatic resection has not been evaluated. Methods:Records of 587 patients who underwent elective hepatic resection and were included in the National Surgical Quality Improvement Program Database were reviewed. MELD score, CTP score, Charlson Index of Comorbidity, American Society of Anesthesiology classification, and age were evaluated for their ability to predict short-term morbidity and mortality. Morbidity was defined as the development of one or more of the following complications: pulmonary edema or embolism, myocardial infarction, stroke, renal failure or insufficiency, pneumonia, deep venous thrombosis, bleeding, deep wound infection, reoperation, or hyperbilirubinemia. The analysis was repeated with patients divided according to their procedure and their primary diagnosis. Parametric or nonparametric analyses were performed as appropriate. Also, a new index was developed by dividing the patients into a development and a validation cohort, to predict morbidity and mortality in patients undergoing elective hepatic resection. ROC curves were also constructed for each of the primary indices. Results:CTP and ASA scores were superior in predicting outcome. Also, patients undergoing resection of primary malignancies had a higher rate of mortality but no difference in morbidity. Conclusion:MELD scores should not be used to predict outcomes in the setting of elective hepatic resection.

The emerging multifaceted roles of nitric oxide

Nitric oxide (NO) is a highly reactive free radical with a multitude of organ specific regulatory functions. Since 1985. NO has been the subject of numerous research efforts and as a result, has been found to play a major role in the cardiovascular, pulmonary, gastrointestinal, immune, and central nervous systems. In addition, deranged NO synthesis is the basis for a number of pathophysiologic states, such as atherosclerosis, pulmonary hypertension, pyloric stenosis, and the hypertension associated with renal failure. Traditional NO donors such as sodium nitroprusside and new pharmacologic NO adducts such as S-nitrosothiols may serve as exogenous sources of NO for the treatment of NO-deficient pathologic states. This review is an attempt to acquaint the surgical community with the fundamentals of NO biochemistry and physiology. Increased knowledge of its functions in normal homeostasis and pathologic states will enable physicians to better understand these disease processes and utilize new pharmacologic therapies.

Continuous intravenous infusion of epoprostenol for the treatment of portopulmonary hypertension.

The association of pulmonary hypertension with portal hypertension, also called portopulmonary hypertension (PPHTN), is a known complication of chronic liver disease. Previously, the presence of PPHTN was considered to be a contraindication to orthotopic liver transplantation (OLT). Although there are selected case reports of successful OLT in the setting of PPHTN, an excessive mortality rate is associated with OLT and PPHTN. Heretofore, therapy for chronic management of PPHTN was lacking. Recently, continuous intravenous infusion of epoprostenol has been demonstrated to improve symptomatology and survival in the general population of patients with primary pulmonary hypertension. We now report the use of epoprostenol in the more specific instance of PPHTN. Over a period of 6-14 months, epoprostenol (10-28 ng/kg/min) therapy was associated with a 29-46% decrease in mean pulmonary artery pressure, a 22-71% decrease in pulmonary vascular resistance, and a 25-75% increase in cardiac output in a group of four patients. These results suggest that effective chronic therapy for PPHTN is available. In conjunction with inhaled nitric oxide as acute intraoperative therapy, epoprostenol infusion represents an additional therapeutic option for treatment of PPHTN in the liver transplant candidate.

Laparoscopic versus open donor nephrectomy: comparing ureteral complications in the recipients and improving the laparoscopic technique.

BACKGROUND Laparoscopic live donor nephrectomy (LDN) is a recently developed procedure, the performance of which needs to be studied. Given the reported advantages in the donors, this study looks at graft outcome and ureteral complications in recipients of kidneys procured by open donor nephrectomy (ODN) versus LDN. METHODS The LDN recipients consisted of 193 patients since 3/27/96. A total of 168 ODN recipients from 1991 to 1998 served as controls. Immunosuppression protocols were similar for both groups. RESULTS Two-year graft survival for LDN and ODN was 98% and 96%, respectively. Two-year patient survival for LDN and ODN was 98% and 97%, respectively. The incidence of delayed graft function and mean serum creatinine at 3 and 12 months was similar in both groups. However, the number of ureteral complications that required operative repair was significantly higher for LDN recipients compared to ODN recipients, 7.7% (n=15) vs. 0.6% (n=1) respectively (P=0.03). Ureteral stenting was required in an additional 3.1% (n=6) of LDN and 2.4% (n=4) of ODN (P=NS). There was, however, a learning curve with time. For the first 130 LDN patients, a total of 20 ureteral complications were recorded, whereas only one occurred in the more recent 63 patients (P=0.03). CONCLUSIONS The higher ureteral complication rate in LDN recipients has improved over time as technical causes have been identified. We have noted significant improvement in ureteral viability by using the endogastrointestinal anastomosis instrument on the ureter and peri-ureteral tissue. LDN is therefore an excellent alternative to ODN. Identification of hazards unique to this technique is critical before its broader application.

A novel approach to the treatment of chronic allograft nephropathy

BACKGROUND Progressive deterioration of renal function in kidney transplant recipients is the leading cause of graft failure. Both nonimmunologic and immunologic mechanisms contribute to this deterioration. METHODS Twenty-eight cyclosporine (CsA)-treated renal transplant recipients (21 cadaveric, 5 living, 2 simultaneous kidney-pancreas) with progressive deterioration of renal function were prospectively enrolled in a clinical trial and had their immunosuppressive regimen changed 24.3+/-7.7 months after transplant. All patients had their CsA dose reduced by 50%, azathioprine was discontinued, and mycophenolate mofetil was added to the medical regimen. The mean creatinine of the patients at the initiation of the change in immunosuppression was 3.5+/-1.2 mg/dl (range 1.9 to 6.2 mg/dl). RESULTS Before the change in immunosuppression, the mean loss in renal function as indicated by the least-squares slope of the reciprocal of creatinine versus time was -0.006+/-0.002 (mg/dl)-1 per month. The change in immunosuppression significantly decreased the rate of loss in renal function for most patients when compared with their pretreatment values with a mean slope of 0.007+/-0.003 (mg/dl)-1 per month (P=0.003). Renal function improved in 21 of 28 patients. Only one patient had continued deterioration of renal function. In a multivariate analysis adjusting for CsA dose, mean arterial blood pressure, and baseline creatinine, the change in immunosuppression was significantly associated with improved renal function (P=0.02). There were no acute rejections after the immunosuppression change. CONCLUSIONS We conclude that adding mycophenolate mofetil and reducing CsA in patients with chronic deterioration of graft function is well tolerated and results in a short-term improvement in renal function.

Beneficial effect of plasmapheresis and intravenous immunoglobulin on renal allograft survival of patients with acute humoral rejection.

Background. Acute humoral rejection (AHR) has been associated with enhanced graft loss. Our study compared the renal allograft survival of patients with AHR treated with plasmapheresis (PP) and intravenous immunoglobulin (IVIG) with allograft survival in patients with acute cellular rejection (ACR). Methods. We retrospectively analyzed all kidney transplants performed at our institution between January 1999 and August 2001 (n=286). Recipients were classified into three groups according to biopsy reports: AHR, ACR, or no rejection. The ACR group was further divided into early and late rejection (<90 and >90 days posttransplant, respectively). Results. After a mean follow-up of 569±19 days, the incidence of AHR was 5.6% (n=16). Recipient presensitization, delayed graft function, early rejection, and higher creatinine at diagnosis were characteristic of AHR. Most AHR patients (14/16) were treated with PP and IVIG. One patient received only IVIG, whereas another received only PP. All AHR patients were given steroid pulses, but only four received antilymphocyte therapy because of concomitant severe ACR. The ACR group comprised 43 patients (15%). One patient with mild rejection received no therapy, 20 improved with steroids alone, and 22 required additional antilymphocyte therapy. One-year graft survival by Kaplan Meier analysis was 81% and 84% in the AHR and ACR groups, respectively (P =NS). Outcomes remained similar when AHR patients were compared with those with early ACR. Conclusions. We conclude that AHR, when diagnosed early and treated aggressively with PP and IVIG, carries a short-term prognosis that is similar to ACR.

One‐Year Results with Extended‐Release Tacrolimus/MMF, Tacrolimus/MMF and Cyclosporine/MMF in De Novo Kidney Transplant Recipients

Once‐daily tacrolimus extended‐release formulation (Prograf XL, formerly referred to as MR or MR4) was compared with the twice‐a‐day tacrolimus formulation (TAC) and cyclosporine microemulsion (CsA), all administered in combination with mycophenolate mofetil (MMF), corticosteroids and basiliximab induction, in a phase 3, randomized (1:1:1), open‐label trial in 638 de novo kidney transplant recipients. In combination with MMF and corticosteroids, XL had an efficacy profile comparable to TAC and CsA. XL/MMF and TAC/MMF were statistically noninferior at 1‐year posttransplantation to CsA/MMF for the primary efficacy endpoint, efficacy failure (death, graft loss, biopsy‐confirmed acute rejection (BCAR) or lost to follow‐up). One‐year patient and graft survival were 98.6% and 96.7% in the XL/MMF group, 95.7% and 92.9% in TAC/MMF group and 97.6% and 95.7% in CsA/MMF group. The safety profile of XL in comparison with CsA was similar to that observed with TAC in this study and consistent with previously published reports of TAC in comparison with CsA. The results support the safety and efficacy of tacrolimus in combination with MMF, corticosteroids and basiliximab induction, as well as XL as a safe and effective once‐daily dosing alternative.

Osteopontin is induced by hedgehog pathway activation and promotes fibrosis progression in nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a leading cause of cirrhosis. Recently, we showed that NASH‐related cirrhosis is associated with Hedgehog (Hh) pathway activation. The gene encoding osteopontin (OPN), a profibrogenic extracellular matrix protein and cytokine, is a direct transcriptional target of the Hh pathway. Thus, we hypothesize that Hh signaling induces OPN to promote liver fibrosis in NASH. Hepatic OPN expression and liver fibrosis were analyzed in wild‐type (WT) mice, Patched‐deficient (Ptc+/−) (overly active Hh signaling) mice, and OPN‐deficient mice before and after feeding methionine and choline–deficient (MCD) diets to induce NASH‐related fibrosis. Hepatic OPN was also quantified in human NASH and nondiseased livers. Hh signaling was manipulated in cultured liver cells to assess direct effects on OPN expression, and hepatic stellate cells (HSCs) were cultured in medium with different OPN activities to determine effects on HSC phenotype. When fed MCD diets, Ptc+/− mice expressed more OPN and developed worse liver fibrosis (P < 0.05) than WT mice, whereas OPN‐deficient mice exhibited reduced fibrosis (P < 0.05). In NASH patients, OPN was significantly up‐regulated and correlated with Hh pathway activity and fibrosis stage. During NASH, ductular cells strongly expressed OPN. In cultured HSCs, SAG (an Hh agonist) up‐regulated, whereas cyclopamine (an Hh antagonist) repressed OPN expression (P < 0.005). Cholangiocyte‐derived OPN and recombinant OPN promoted fibrogenic responses in HSCs (P < 0.05); neutralizing OPN with RNA aptamers attenuated this (P < 0.05). Conclusion: OPN is Hh‐regulated and directly promotes profibrogenic responses. OPN induction correlates with Hh pathway activity and fibrosis stage. Therefore, OPN inhibition may be beneficial in NASH (HEPATOLOGY 2011)

The effect of mandibular osteotomy in three patients with hypersomnia sleep apnea

Hypersomnia sleep apnea (HSA) is characterized by apneic episodes during sleep and daytime hypersomnolence. Patients afflicted as a result of upper airway obstruction have been treated traditionally with permanent tracheostomy. Three patients with HSA and mandibular retrognathism are presented. Each patient had a retrognathic mandible that stemmed from a different cause. Surgical advancement of their underdeveloped mandibles corrected the symptoms of HSA rapidly. The literature concerning HSA is reviewed and the advantages of mandibular surgery in selected cases are discussed.