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Biomedical subjects

W Scott Helton

Publications and source records attributed to W Scott Helton.

At least 19 recordsLinked to original sources
PubMed2006

Intraductal papillary mucinous neoplasms of the pancreas.

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are rare tumors with different characteristics than conventional ductal pancreatic adenocarcinomas. Although they are commonly classified as cystic neoplasms of the pancreas, within their own subgroup of pancreatic cystic tumors, they are unique in their presentation, histologic characteristics, treatment, and survival rates. Currently, strategies are being implemented to better characterize these tumors preoperatively. Once IPMN is diagnosed, treatment strategies are based upon multiple factors, including patient condition, symptoms, and type and extent of disease. Although these factors may determine different treatment strategies, surgery remains the mainstay of therapy due to the favorable survival rate if the disease is diagnosed and treated prior to the development of invasive carcinoma. The goal of treatment is to alleviate symptoms and to extirpate disease prior to its transition to malignancy, invasion, and metastases. Although some experts advocate a nonoperative approach to patients with suspected benign disease, the risk of progression to malignancy can present a dilemma for the treating physician and patient. Unfortunately, differentiation of benign from malignant disease can only be determined conclusively following complete review of the entire surgical specimen. To further complicate treatment strategies, IPMN is a multifocal disease, and additional lesions can develop in the remnant pancreas. This fact has compelled most physicians familiar with the disease to institute lifelong surveillance for patients with the disease. Although our understanding of IPMN has increased greatly since its initial description in 1982, the natural history of the disease is poorly defined, and there is no consensus among experts on standards of practice. Although additional long-term follow-up of greater numbers of patients and their response to various interventions are necessary to develop consensus-based practice guidelines, this review will discuss our treatment recommendations based upon a review of the literature.

Journal Article↗
PubMed2006

Adverse clinical consequences of hyperglycemia from total parenteral nutrition exposure during hematopoietic stem cell transplantation.

Immunocompromised hematopoietic stem cell transplant (HSCT) recipients frequently receive total parenteral nutrition (TPN), a dextrose-based solution that may exacerbate the infectious risks associated with hyperglycemia. This study assessed the incidence of hyperglycemia (glucose level>or=110 mg/dL) and its effect on clinical outcomes in TPN versus non-TPN recipients who received HSCTs. A retrospective cohort of 357 adults who were admitted for initial autologous or allogeneic transplantation at 2 university-affiliated centers was examined. To discern the temporality of outcomes, "before" and "after" comparisons were made by using actual infusion times for TPN patients and using timeframes based on mean hospital days before ("before") or during ("after") parenteral infusion for non-TPN patients. Patients demonstrated similar demographic and clinical characteristics when analyzed by institution, feeding, and donor-type strata, and 57% received TPN. After attempts to equilibrate disease acuity were employed, the proportion of hyperglycemic days was equivalent before but significantly greater after in patients exposed versus unexposed to TPN (87.5% versus 8.3%, respectively; P<.001). Using logistic regression, the likelihood of infection doubled (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.4-3.5) after adjustment for donor type, diagnosis, age, gender, ethnicity, institution, mucositis, and obesity. This association was only slightly attenuated when patients with infections before were removed (OR, 1.9; 95%, CI, 1.1-3.3), steroid recipients were eliminated (OR, 2.1; 95% CI, 1.2-3.4), and when patients with nonablative regimens were excluded (OR, 2.1; 95% CI, 1.3-3.5), but was considerably higher for patients who were classified as normal or underweight (body mass index<or=25 kg/m2; n=118; OR, 4.3; 95% CI, 1.7-10.6). In addition, the effect of TPN became insignificant when glucose was added as an independent variable, thus symbolizing their collinear relation. Parenteral nutrition recipients versus nonrecipients also developed significantly greater requirements for red cell (P=.001) and platelet transfusions (P=.001) after and significant delays in granulocyte and platelet engraftment times for autologous (P=.01) and allogeneic (P=.02) subjects. The broad use of TPN in patients undergoing initial HSCT was associated with profound hyperglycemia, resultant greater morbidity, and questionable efficacy in this adult, well-nourished cohort.

Adult↗
PubMed2006

Does the literature support an indication for hepatic metastasectomy other than for colorectal primary?

Hepatic resection for colorectal hepatic metastatic disease has been demonstrated to have a significant outcome benefit for selected patients. Advances in anesthetic and surgical technique have resulted in a significantly reduced morbidity and mortality for this procedure, and this management approach has become widely practiced. This hepatic resection paradigm is also being applied to hepatic metastatic disease of noncolorectal origin. The purpose of this report is to review and summarize the reported literature in order to define if the current data support an indication for hepatic metastasectomy. The specific cancer primaries that this analysis evaluated include breast, melanoma, gynecologic, neuroendocrine, sarcoma, and gastric cancer. Based on the data examined, we propose that although hepatic metastasectomy for noncolorectal cancer may be a promising component of overall oncologic treatment, the role of surgical resection cannot be generalized and at present should be individualized based on the patient's clinical course and by the biologic behaviors of specific malignancies.

Breast Neoplasms↗
PubMed2006

SURGISIS-assisted surgical site control in the delayed repair of a complex bile duct injury after laparoscopic cholecystectomy.

Although laparoscopic cholecystectomy has revolutionized the surgical approach to patients with gallbladder disease, it has also brought a marked increase in the incidence of complex and serious bile duct injuries. Many of these major injuries represent a major technical challenge for even the most seasoned hepatobiliary-trained surgeon. Herein, we present a case outlining the algorithmic treatment approach for delayed-presentation complex biliary injury and report on the novel use of small intestinal submucosal biomaterial for surgical site control in the staged repair of a complex biliary injury (Strasberg E4) after laparoscopic cholecystectomy.

Aged↗
PubMed2006

Abdominal wall reconstruction using biological tissue grafts: present status and future opportunities.

Surgeons often encounter the challenge of treating acquired abdominal wall defects following abdominal surgery. The current standard of practice is to repair most defects using permanent synthetic mesh material. Mesh augments the strength of the weakened abdominal wall fascia and enables the hernia repair to be performed in a tension-free manner. However, there is a risk of acute and/or chronic infection, fistula formation and chronic abdominal wall pain with the use of permanent mesh materials, which can lead to more complex operations. As a means to avoid such problems, surgeons are turning increasingly to the use of xenogenic and allogenic materials for the repair of abdominal wall defects. Their rapid evolution and introduction into the clinical operating room is leading to a new era in abdominal wall reconstruction. There are promising, albeit limited, clinical data with short-term follow-up for only a few of the many biological tissue grafts that are being promoted currently for the repair of abdominal hernias. Additional clinical studies are required to better understand the long-term efficacy and limitations of these materials.

Abdominal Muscles↗
PubMed2005

Short-term outcomes with small intestinal submucosa for ventral abdominal hernia.

HYPOTHESIS: A bioabsorbable tissue scaffold of porcine submucosal small intestine extracellular matrix (Surgisis Gold [SIS]; Cook Biotech Inc, West Lafayette, Ind) mesh is safe and effective for ventral hernia repair. DESIGN: Retrospective case series at a university teaching hospital. PATIENTS: Fifty-three consecutive patients having 8-ply SIS mesh repair of ventral abdominal hernias. MAIN OUTCOME MEASURES: Early complications, reoperation, hernia recurrence, mesh or wound infection, or reaction. Outcomes reported and compared on an intention-to-treat basis. RESULTS: Patients were stratified by wound class: clean, clean-contaminated and contaminated, or dirty. Median follow-up was 14 months (range, 2-29 months) during which there were 22 complications (41%), 17 early reoperations (32%), 13 partial dehiscences (21%), 6 mesh reactions (11%), and 9 recurrent hernias (17%). Seven recurrent hernias (78%) in critically ill, patients with dirty wounds had the SIS mesh removed owing to infection or reoperation. In patients without SIS mesh removal or debridement, 1 (2.2%) of 44 developed a recurrent hernia at 6 months. Patients with dirty wounds were more likely to need early reoperation (P<.001), develop a complication (P<.01), partial wound dehiscence (P<.05), or recurrent hernia (P<.01) compared with patients with clean wounds. Critically ill patients were more likely to have hernia recurrence (P<.05), early reoperation (P<.001), and postoperative complications (P<.05). CONCLUSIONS: Eight-ply SIS mesh is safe in clean and clean-contaminated hernia repair with satisfactory short-term outcomes. However, delayed wound infection, repeated operation, and mesh debridement warrant cautious use of SIS mesh in critically ill patients and those with dirty wounds.

Critical Illness↗
PubMed2003

Early experience employing a linear hepatic parenchyma coagulation device.

BACKGROUND: In recent years, hepatic resection for primary and metastatic disease has been facilitated by improved anesthetic and surgical techniques, as well as by the application of new technologies. Historically, the major complications associated with hepatic resection have been postoperative bleeding, bile leak, and liver failure. Resection techniques and devices that minimize hemorrhage and bile leak, and enable the preservation of functional hepatic parenchyma, have been useful in the surgical management of liver tumors. METHODS: Herein, the use of a radiofrequency powered device for the pretransection coagulation of hepatic tissue that simultaneously seals blood vessels and bile ducts 3 mm in diameter or smaller is described. RESULTS: Early results from our single-center experience with the use of this linear radiofrequency device are reported. Seven patients underwent liver resection for either hepatocellular carcinoma or colorectal cancer metastases. There were no postoperative bile leaks, hemorrhage, or hepatic insufficiency. No transfusions were required, and the mean estimated blood loss for the parenchymal transection phase was less than 165 cc. CONCLUSIONS: The linear radiofrequency device is expedient for the pretransection coagulation of hepatic tissue and, thus, facilitates liver resection.

Aged↗
PubMed2003

Auto-islet transplantation after pancreatectomy.

Chronic pancreatitis (CP) is an inflammatory disease that causes progressive and irreversible structural changes to the pancreas, resulting in permanent impairment of both endocrine and exocrine functions. In advanced cases of CP, pain can be relieved only with pancreatic resection. However, even partial resection of the pancreas in this setting may cause diabetes. Furthermore, postsurgical diabetes (PSD) always occurs after total or near-total pancreatectomy, which is commonly performed for CP. Auto transplantation of pancreatic islets into the portal vein after pancreatic resection can prevent PSD. The results of this strategy, which are already encouraging, are likely to improve in the near future because of significant progress in the isolation and preservation of pancreatic islets. This review discusses the current status and future prospects for auto-islet transplantation after pancreatic resection for CP.

Diabetes Mellitus↗
PubMed2003

Omega-3 fatty acids: implications for the treatment of tumor-associated inflammation.

Our in vivo and in vitro studies using omega-3 fatty acids (FA) have provided insight into the biological effects and mechanisms of their anti-inflammatory action(s). The implications for this research are profound because there are few nutritional therapies available that have the potential to be clinically effective in malignancies and other chronic inflammatory conditions as omega-3 FA. In this summary of experiments the biological effects of omega-3 FA are discussed and the potential mechanisms of action presented.

Angiogenesis Inducing Agents↗
PubMed2002

NF-kappa B inhibition by omega -3 fatty acids modulates LPS-stimulated macrophage TNF-alpha transcription.

Omega-3 fatty acid (FA) emulsions reduce LPS-stimulated murine macrophage TNF-alpha production, but the exact mechanism has yet to be defined. The purpose of this study was to determine the mechanism for omega-3 FA inhibition of macrophage TNF-alpha production following LPS stimulation. RAW 264.7 cells were pretreated with isocaloric emulsions of omega-3 FA (Omegaven), omega-6 FA (Lipovenos), or DMEM and subsequently exposed to LPS. IkappaB-alpha and phospho-IkappaB-alpha were determined by Western blotting. NF-kappaB binding was assessed using the electromobility shift assay, and activity was measured using a luciferase reporter vector. RT-PCR and ELISA quantified TNF-alpha mRNA and protein levels, respectively. Pretreatment with omega-3 FA inhibited IkappaB phosphorylation and significantly decreased NF-kappaB activity. Moreover, omega-3-treated cells demonstrated significant decreases in both TNF-alpha mRNA and protein expression by 47 and 46%, respectively. These experiments demonstrate that a mechanism for proinflammatory cytokine inhibition in murine macrophages by omega-3 FA is mediated, in part, through inactivation of the NF-kappaB signal transduction pathway secondary to inhibition of IkappaB phosphorylation.

Animals↗
PubMed2002

Modulation of lipopolysaccharide-stimulated macrophage tumor necrosis factor-alpha production by omega-3 fatty acid is associated with differential cyclooxygenase-2 protein expression and is independent of interleukin-10.

BACKGROUND: The role of omega-3 fatty acids (FA) as anti-inflammatory agents involves the inhibition of macrophage (Mphi) cytokine production, but the mechanisms involved are not well defined. The effects of omega-3 FA on the transcription and translation of cyclooxygenase-2 (COX-2), the production of prostaglandin E(2) (PGE(2)), and the production of interleukin-10 (IL-10) were investigated as potential mechanisms for the down-regulation of lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha production. METHODS: RAW 264.7 Mphi were incubated with Omegaven (10 mg% omega-3 FA), Lipovenos (10 mg% omega-6 FA), or DMEM for 4 h of pretreatment. The cells were then exposed to LPS (1 microg/ml) or medium alone for 3 h. COX-2 mRNA levels were determined by semi-quantitative reverse transcriptase polymerase chain reaction, and COX-2 protein levels were determined by Western blotting. The levels of PGE(2) and IL-10 proteins secreted into the medium were quantified using enzyme-linked immunosorbent assays. RESULTS: Pretreatment with omega-3 FA increased Mphi COX-2 protein expression levels without altering the levels of COX-2 mRNA in response to LPS stimulation. In addition, pretreatment with omega-3 FA dramatically decreased the PGE(2) and IL-10 production induced by LPS, whereas pretreatment with an equivalent dose of omega-6 FA only resulted in a modest increase in PGE(2) and a slight decrease in IL-10 production compared to controls. CONCLUSION: As COX-2 protein levels were increased without a change in COX-2 mRNA levels with omega-3 FA pretreatment, this suggested that omega-3 FA did not upregulate COX-2 at the transcriptional level. The omega-3 FA may instead posttranscriptionally stabilize existing COX-2 mRNA. The increased COX-2 expression may thus be explained by increased translation of COX-2 and/or decreased COX-2 degradation. The decreased PGE(2) production could be attributed to the replacement of Mphi membrane omega-6 FA substrates by omega-3 FA and the competitive inhibition of COX-2 enzyme by omega-3 FA. The reduction of active COX-2 product associated with an increase in COX-2 enzyme implies the existence of a negative feedback mechanism. Surprisingly, IL-10 production was decreased by omega-3 FA pretreatment, indicating that the reduced IL-10 inhibition of Mphi cytokine production was superceded by the other actions of omega-3 FA.

Animals↗
PubMed2002

Virtual reality: immersive hepatic surgery educational environment.

BACKGROUND: Understanding the spatial relationships among the liver segments, and intrahepatic portal and hepatic veins is essential for surgical treatment of liver diseases. Teleimmersive virtual reality enables improved visualization over conventional media because it supports stereo vision, viewer-centered perspective, large angles of view, and interactivity with remote locations. We report a successful pilot study teaching hepatic surgical principles using teleimmersion. METHODS: We developed a teleimmersive environment for teaching with biomedical models including virtual models of the liver segments and portal and hepatic veins. Using the environment, 1 instructor gave a workshop to 6 senior general surgery residents at 2 physical locations. A 24-question (36-point) examination was administered before and after the workshop. RESULTS: The workshop produced significant improvements in the mean test scores between the pretests and posttests (17.67 to 23.67, P <.02). We found no differences between residents who were with the instructor and those at the remote location. Six-month delayed testing demonstrated complete retention of new knowledge. CONCLUSIONS: The teleimmersive environment enabled surgeons to overcome some of the barriers to teaching complex surgical anatomic principles. Using teleimmersive environments, surgical educators and trainees can interact from locations worldwide using virtual anatomic information to achieve their educational goals.

Biliary Tract↗
PubMed2002

Omega-3 fatty acid lipid emulsion reduces LPS-stimulated macrophage TNF-alpha production.

BACKGROUND: Omega-3 (omega-3) fatty acids (FA), specifically eicosapentaenoic acid (EPA), attenuate cytokine-mediated inflammation. Currently, in the United States, there is no commercial source of omega-3 lipid for clinical use. A clinically used European lipid emulsion, Omegaven, has been shown to have beneficial antiinflammatory effects; however, the mechanisms of its action are not well defined. In the present work, this omega-3 FA emulsion has been evaluated in order to define its effects on TNF-alpha production in a model of LPS-stimulated macrophages. MATERIALS AND METHODS: RAW 264.7 cells (1 x 10(6) cell/well) were incubated with DMEM, Omegaven, or an isoenergetic omega-6 lipid emulsion, Lipovenos for 4 h. Cells were washed and then stimulated with LPS (1 microg/mL) or media alone for 3 h. Plate well supernatants were collected and assayed for TNF-alpha production by ELISA. Statistical analysis was performed by ANOVA and post-hoc analyses; the significance was defined as p < 0.05. RESULTS: Unstimulated RAW cell TNF-alpha production was similar in all groups and < 60 pg/mL. Lipovenos pretreatment did not alter TNF-alpha production from that of baseline compared to LPS-stimulated cells. Four-hour Omegaven pretreatment significantly reduced TNF-alpha production in LPS-stimulated cells, with a 46% reduction in TNF-alpha from baseline observed. CONCLUSION: Four-hour omega-3 FA emulsion pretreatment significantly attenuated LPS-stimulated macrophage TNF-alpha production. These data support the contention that antiinflammatory effects of omega-3 FA occur at least in part through the inhibition of macrophage TNF-alpha production in response to endotoxin. Further studies to define the antiinflammatory mechanisms of omega-3 FA on macrophages are warranted. The availability of Omegaven as an experimental treatment and Lipovenos as an equivalent control will be useful for future studies.

Animals↗